TWI820894B - Motor driving system and torque distribution method - Google Patents

Abstract

A motor driving system is disclosed. The motor driving system comprises a driving circuit and a controller. The driving circuit supplies driving current to a motor. The controller comprises a current command generation unit. The current command generation unit outputs a current command which corresponds to a torque command received by the controller and the state of the motor. The current command includes a d-axis and/or a q-axis current command. The controller converts the driving current into d-axis and/or q-axis current, and controls the driving circuit so that the driving current approaches the d-axis and/or q-axis current corresponding to the current command. The current command generation unit includes a maximum torque per amp table and a zero-recovery characteristic table. When the torque command is a positive torque output, the current command generating unit outputs the current command according to the maximum torque per ampere table, and when the torque command is a negative torque output, the current command generating unit outputs the current command according to the zero-recovery characteristic table.

Description

Electric motor drive system and torque distribution method

This case belongs to the field of electric motors, especially an electric motor drive system and a torque distribution method.

The motor drive system usually includes a DC power supply end, a drive circuit and a motor. When the motor is powered on and running, power can be supplied and received in both directions between the DC power supply end, the drive circuit and the motor. To further explain, when the drive circuit drives the motor to operate based on the torque command with positive torque output, the motor will generate positive torque to push the mechanical load to rotate forward; conversely, when the drive circuit drives the motor to operate based on the torque command with negative torque output , the motor will generate negative torque to resist the positive torque of the current mechanical load, and generally speaking, when the motor will generate negative torque, the motor will also generate regenerative energy, which can be recycled, such as in a motor drive system. When the DC power supply terminal is composed of a secondary battery, the regenerated energy can be recovered to charge the secondary battery of the motor drive system.

However, under special conditions, if the regenerative energy generated by the motor cannot be effectively recovered, there will be defects in the motor drive system. For example, when an electric motor is used in a high-speed railway train, if the train brakes while running at high speed and encounters a power interruption, the regenerative energy recovered from the drive circuit to the DC power supply end will have nowhere to be consumed, causing damage to the drive circuit, or pushing the regenerative energy out of the system. Integration into the power grid will cause island effect hazards. Another example is when an electric motor is used in an electric vehicle. If the electric vehicle is fully charged and driven up a mountain, the capacity of the motor's secondary battery will be halved due to the low temperature on the mountain. Therefore, frequent use of the brakes when going down the mountain will prevent the secondary battery from being regenerated. Energy, causing electric vehicles to switch to mechanical braking methods. As a result, electric vehicles may overheat or be unable to effectively consume regenerative energy. For another example, when electric motors are used in plug-in hybrid vehicles (PLUG-IN HYBRID ELECTRIC VEHICLE, PHEV) or fuel cell vehicles, since the main power supply source is the internal combustion engine or fuel cell, the energy storage capacity of the secondary battery in the vehicle Smaller, which means the secondary battery may not be able to instantly recycle the larger regeneration energy, making it impossible to use motor braking. Although a combination of supercapacitors and braking resistors can be added for motor braking, this also results in a reduction in the available internal space of the vehicle. , while increasing the cost of the vehicle, causing the weight of the vehicle to become heavier and affecting the endurance of the vehicle.

Therefore, how to develop a motor drive system and torque distribution method that overcomes the above deficiencies is currently the most urgent issue to be solved.

The purpose of this case is to provide a motor drive system so that the motor does not regenerate and recover energy. The controller of the motor drive system cooperates with the zero recovery characteristic table of the controller to correspond to the output current command according to the torque command and the motor state of the motor to control The operation of the electric motor, and then Let the regenerative energy generated by the motor be completely suppressed by the energy loss of the motor. This not only increases the application scenarios of the motor and improves the reliability of the braking process, but also reduces the wear and excessive heat energy accumulation of the mechanical brake. In addition, it also avoids the impact of regenerative energy on the motor. The electric motor drive system causes damage, but also because the electric motor drive system does not need to set up other additional devices to consume regenerated energy, the space utilization of the electric motor drive system is increased and the production cost is reduced.

Another purpose of this case is to provide an electric motor drive system and a torque distribution method. When the electric motor drive system receives a torque command, it will control the cooperation of two electric motors to enhance the braking operation capability of the electric motor drive system and provide more accurate information in emergency situations. Large negative torque output improves safety.

Another purpose of this case is to provide an electric motor drive system and a torque distribution method. When the electric motor drive system receives a torque command, it will control the cooperation of two electric motors, so that the regenerative energy generated by the electric motor can be matched to the battery charging curve. The secondary battery is charged, thereby protecting the secondary battery.

In order to achieve the above purpose, one of the broader implementation aspects of this project is to provide a motor drive system, including: a drive circuit, which converts input power and supplies drive current to the motor and drives the motor; and a controller, which further includes a current The command generation unit, the current command generation unit outputs a current command corresponding to the torque command received by the controller and the motor status. The current command includes a d-axis current command and/or a q-axis current command, and the controller converts it into a d-axis current and a q-axis current command based on the drive current coordinates. /or q-axis current, and controls the drive circuit so that the drive current approaches the d-axis current command and/or q-axis current command corresponding to the current command; wherein, the current command generation unit further includes a maximum torque table per ampere and a zero recovery characteristic The maximum torque table per ampere is based on the minimum energy loss of the motor and converts the torque command according to the motor status. Switching to a current command, the zero recovery characteristic table converts the torque command into a current command according to the motor state when the motor energy loss and regeneration recovery energy cancel each other out; among them, when the controller receives a torque command and it is a positive torque output, the current command generation unit The current command corresponding to the maximum torque table per ampere is output. When the torque command received by the controller is a negative torque output and the motor drive system does not include a primary and secondary battery, the current command generating unit outputs the corresponding current command according to the zero recovery characteristic table.

In order to achieve the above purpose, another broader implementation form of this project is to provide a motor drive system, including: a motor, including a first motor and a second motor; a drive circuit, including a first drive circuit and a second drive circuit, respectively. The input power converts and supplies the first driving current and the second driving current to the corresponding first and second electric motors, and drives the corresponding first electric motor and the second electric motor respectively; and a controller, which includes a torque distribution unit, The first controller and the second controller, the torque distribution unit receives a torque command and distributes a first torque command and a second torque command to the corresponding first controller and the second controller respectively; the first controller and The second controller further includes a first current command generating unit and a second current command generating unit respectively. The first and second current command generating units respectively output the first current command and the second current command corresponding to the first and second torque commands and The first and second motor states, the first current command includes the first d-axis current command and/or the first q-axis current command, the second current command includes the second d-axis current command and/or the second q-axis current command, the controller correspondingly converts the first and second drive current coordinates into d-axis current and/or q-axis current and controls the corresponding first and second drive circuits so that the first and second drive currents approach the a d-axis current and/or q-axis current corresponding to the second current command; wherein the first and second current command generating units respectively include a first negative torque current characteristic table and a second negative torque current characteristic table, the first and The second negative torque current characteristic table is for converting the first and second motors according to the states of the first and second motors respectively when the corresponding first and second motors have negative torque output. The two torque commands are converted into a first current command and a second current command; when the first controller receives the first torque command as a negative torque output, the first current command generating unit outputs the corresponding first current command according to the first negative torque current characteristic table. a current command; and when the second controller receives the second torque command as a negative torque output, the second current command generating unit outputs the corresponding current command according to the second negative torque current characteristic table.

In order to achieve the above purpose, another broader implementation aspect of this case is to provide a torque distribution method, which is applied in a torque distribution unit such as a controller of an electric motor drive system. The torque distribution method includes the steps: (s10) based on the torque command. Calculation of the first torque command; (s11) Determine whether the battery voltage of the secondary battery is greater than the preset reference voltage; (s12) When the judgment result of step (s11) is that the battery voltage is greater than the reference voltage, increase the reference current; ( s13) Determine whether the reference current is greater than the maximum charging current command; (s14) When the judgment result of step (s13) is that the reference current is greater than the maximum charging current command, limit the reference current to be equal to the maximum charging current command; (s15) Determine whether the reference current is greater than The battery current of the secondary battery; (s16) When the judgment result in step (s15) is that the reference current is greater than the battery current, increase the first torque command; (s17) Judge whether the first torque command is greater than the torque command; (s18) When the step When the judgment result of (s17) is that the first torque command is greater than the torque command, the first torque command is limited to be equal to the torque command; (s19) the first torque command is output; (s20) based on the subtraction of the torque command and the first torque command As a result, the second torque command is output; (s21) when the judgment result of step (s11) is that the battery voltage is not greater than the reference voltage, reduce the reference current and execute step (s15); and (s22) when the judgment result of step (s15) When the result is that the reference current is not greater than the battery current, the first torque command is reduced and step (s19) is executed; when the judgment result of step (s13) is that the reference current is not greater than the maximum charging current command, step (S15) is executed.

1, 1a, 1b: Motor drive system

2:Controller

3: Electric motor

4: Drive circuit

Is: drive current

Tn: Torque command

Idcom: d-axis current command

Iqcom: q-axis current command

20:Current command generation unit

21: Speed and angle detector

22:PI controller

23:Current conversion device

24:Voltage conversion device

25: Pulse width modulation device

ω: Speed information

θ: Angle information

Ia, Ib, Ic: single-phase current

Id: d-axis current

Iq: q-axis current

Vdcom: d-axis voltage command

Vqcom: q-axis voltage command

Vabc: drive voltage command

PWM: pulse width modulation signal

min: minimum drive current

S1: first speed

S2: second speed

S3: The third speed

S4: The fourth speed

T1: first negative torque value

T2: The second negative torque value

spec: specific drive current

Is_a: first drive current value

Is_b: second drive current

8: Temperature detector

5: Secondary battery

Tm: temperature information

6:Torque distribution unit

2a: First controller

2b: Second controller

40: First drive circuit

41: Second drive circuit

30:First electric motor

31:Second electric motor

Tn1: first torque command

Tn2: Second torque command

Vd: battery voltage

Ie: battery current

V1: first reference voltage interval

I1: first reference current interval

V2: second reference voltage range

I2: second reference current interval

V3: The third reference voltage range

I3: The third reference current interval

t0~t4: time

7: Electric vehicle system

S10~S22: Steps of torque distribution method

Figure 1 is a system block diagram of the motor drive system of the first preferred embodiment of this case; Figure 2 is a diagram of the drive current received by the motor of the motor drive system shown in Figure 1 under different torques and different speeds. Schematic diagram of the relationship between the maximum value and power; Figure 3 is a schematic diagram of the relationship between the torque command received by the motor drive system shown in Figure 1 and the maximum value of the drive current received by the motor in the d-axis and q-axis coordinates; Figure 4 The figure is a system block diagram of the motor drive system of the second preferred embodiment of this case; Figure 5 is a system block diagram of the motor drive system of the third preferred embodiment of this case; Figure 6 is the motor drive shown in Figure 5 Schematic diagram of the voltage/current charging curve of the system's secondary battery during charging operation.

FIG. 7 is a schematic diagram of the steps of the torque distribution method of the torque distribution unit of the electric motor drive system shown in FIG. 5 .

Some typical embodiments embodying the features and advantages of this case will be described in detail in the following description. It should be understood that this case can have various changes in different aspects without departing from the scope of this case, and the descriptions and illustrations are essentially for illustrative purposes rather than limiting the scope of this case.

Please refer to Figures 1, 2 and 3. Figure 1 is a system block diagram of the motor drive system of the first preferred embodiment of this case, and Figure 2 is a system block diagram of the motor drive system shown in Figure 1. Schematic diagram of the relationship between the maximum driving current received by the motor and the power under different torques and different speeds of the motor. Figure 3 shows the relationship between the torque command received by the motor drive system shown in Figure 1 and the drive current received by the motor. Schematic diagram of the relationship between the maximum value in the d-axis and q-axis coordinates. The motor drive system 1 of this embodiment can be used in, but is not limited to, high-speed railway trains, electric vehicles, plug-in hybrid vehicles, fuel cell vehicles, etc., and high-speed railway trains, electric vehicles, plug-in hybrid vehicles, and Each fuel cell vehicle contains an electric vehicle system 7 used to control its overall operation.

The motor drive system 1 includes a controller 2 , a motor 3 and a drive circuit 4 . The drive circuit 4 may be, but is not limited to, composed of an inverter that can transmit electric energy in both directions, and is electrically connected to the motor 3 to convert the received input power and supply the drive voltage and drive current Is to the motor 3 to drive. The electric motor 3 performs positive torque operation or negative torque operation. The circuit structure of the drive circuit 4 is already common in the field of electric motors and will not be described in detail here.

The motor 3 can drive the load (not shown) to rotate, that is, the motor 3 drives the load to rotate forward when operating with positive torque, and drives the load to rotate negatively when operating with negative torque. When the motor 3 operates with positive torque, the motor 3 will It operates in the motor mode, and when the motor 3 needs to brake and perform negative torque operation, the motor 3 will generally operate in the generator mode to generate regenerative energy. For ease of explanation, this case will take motor 3 as a three-phase motor as an example, but this is not a limitation.

The controller 2 may receive a torque command Tn from the electric vehicle system 7 , where the torque command Tn may be a positive torque output to drive the electric motor 3 to perform positive torque operation, or the torque command Tn may be a negative torque output to drive the electric motor 3 3 Perform negative torque operation. In addition, the controller 2 further includes a current command generating unit 20. The current command generating unit 20 outputs a current command, where the current command is generated corresponding to the torque command Tn received by the controller 2 and the motor state of the motor 3, and the current command includes d. Axis current command Idcom and/or q-axis current command Iqcom, and the controller 2 can convert the coordinates into the d-axis current Id and/or q-axis current Iq according to the drive current Is, and control the drive current Is of the drive circuit 4 to approach the current command. Corresponding d-axis current command and/or q-axis current command.

In addition, the current command generation unit 20 further includes a maximum torque per ampere table and a zero recovery characteristic table. The maximum torque per ampere table records that the current command generation unit 20 generates the torque command Tn according to the motor state when the energy loss of the motor 3 is minimized. The conversion comparison table that converts into a current command, the zero recovery characteristic table records the conversion comparison that allows the current command generation unit 20 to convert the torque command Tn into a current command according to the motor state when the energy loss of the motor 3 and the regeneration recovery energy cancel each other. table, where the motor state referred to here may include the rotation speed of the motor 3 and so on. What's more, when the torque command Tn received by the controller 2 is a positive torque output, the current command generating unit 20 outputs the corresponding current command according to the maximum torque table per ampere. When the torque command Tn received by the controller 2 is a negative torque output, , the current command generating unit 20 outputs the corresponding current command according to the zero recovery characteristic table.

In some embodiments, the controller 2 further includes a rotation speed and angle detector 21, a PI controller 22, a current conversion device 23, a voltage conversion device 24 and a pulse width modulation device 25. The rotation speed and angle detector 21 is used to generate rotation speed information ω according to the rotation speed of the motor 3, and generate angle information θ according to the rotation angle of the motor 3. The motor status of the motor 3 includes the rotation speed information ω and can be provided to the current command generation Unit 20, the angle information θ can be provided to the current conversion device 23 and the voltage conversion device 24 respectively. The current conversion device 23 captures the drive current Is flowing into the motor 3 to obtain a current corresponding to the drive current Is (for example, the drive current Is is a three-phase drive current, then the current conversion device 23 captures the drive current Is to obtain a single-phase Currents Ia, Ib and Ic (as shown in Figure 1), and coordinate conversion is performed on the single-phase currents Ia, Ib and Ic that reflect the driving current Is according to the angle information θ to generate the d-axis current Id and/or the q-axis Current Iq. PI controller 22 PI control is performed based on the d-axis current Id and/or q-axis current Iq and the d-axis current command Idcom and/or q-axis current command Iqcom to output the d-axis voltage command Vdcom and/or the q-axis voltage command Vqcom. The voltage conversion device 24 receives the d-axis voltage command Vdcom and/or the q-axis voltage command Vqcom, and performs coordinate conversion on the d-axis voltage command Vdcom and/or the q-axis voltage command Vqcom according to the angle information θ to generate a three-phase driving voltage. CommandVabc. The pulse width modulation device 25 generates a corresponding pulse width modulation signal PWM to the switching element (not shown) of the drive circuit 4 according to the drive voltage command Vabc to adjust the drive voltage and drive current Is provided by the drive circuit 4 to the motor 3 , thereby making the drive current Is of the drive circuit 4 approach the d-axis current command and/or the q-axis current command corresponding to the current command.

Of course, the motor 3 is not limited to a three-phase motor, as long as it is a permanent magnet synchronous servo motor (PMSM). For example, the motor 3 can be a multi-phase motor, and the corresponding motor 3 is a multi-phase motor, then the drive circuit 4 provides multi-phase driving voltage and multi-phase driving current to the motor 3, and the current conversion device 23 captures the multi-phase driving current flowing into the motor 3 to obtain each single-phase current, and converts each single-phase obtained according to the angle information θ The current undergoes coordinate conversion to generate a d-axis current Id and/or a q-axis current Iq. In addition, the voltage conversion device 24 receives the d-axis voltage command Vdcom and/or the q-axis voltage command Vqcom, and converts the d-axis voltage command according to the angle information θ. Vdcom and/or the q-axis voltage command Vqcom performs coordinate conversion to generate a multi-phase driving voltage command, and the pulse width modulation device 25 generates a corresponding pulse width modulation signal PWM to the driving circuit according to the multi-phase driving voltage command. 4 switching elements.

Please refer to Figures 2 and 3 again. Figure 2 shows four different types of lines. The first type of lines represents the maximum value of the driving current Is received by the motor 3 in this case and the energy of the motor 3. The relationship between losses is marked as energy loss in Figure 2. This line increases with the maximum drive current Is. The value becomes larger and exhibits an exponential rising relationship, and the energy loss of the electric motor 3 is not affected by differences in torque commands and differences in the motor status of the electric motor 3, such as rotational speed.

The second type of line represents the relationship between the maximum value of the drive current Is and the regenerated energy of the motor 3 when controlled by Maximum Torque Per Ampere (MTPA, hereinafter referred to as MTPA). It is noted as MTPA in Figure 2. The second type of lines exhibits a linear relationship. In a traditional motor drive system, when the motor drive system receives a torque command, it is generally based on the MTPA control method and outputs the drive current received by the motor according to the different torque commands, so as to match the torque command. Minimum drive current (when the motor drive system 1 in this case receives the torque command Tn which is a negative torque output, the second type of line can also be regarded as the maximum drive current Is presented by the motor 3 in this case based on the MTPA control method. relationship with the regenerative energy of the motor 3), so that the motor drive system can achieve optimal efficiency (i.e. minimum energy loss) when operating according to the torque command. Therefore, as shown in Figure 3, when the d-axis In the coordinate system composed of current and q-axis current, the shortest distance between the origin of zero d-axis current and zero q-axis current and the torque command is the minimum driving current Is selected according to the torque command Tn in the MTPA control mode. (Min marked on Figure 3 represents the minimum driving current min when the shortest distance is between the origin where the d-axis current is zero and the q-axis current is zero and the torque command Tn). In addition, since different rotational speeds of the electric motor 3 will result in different regenerative energy generated by the electric motor 3, the second type of lines is shown as four lines in Figure 2, respectively showing different rotational speeds of the electric motor 3, which are marked as the second line in Figure 2. The first rotational speed S1, the second rotational speed S2, the third rotational speed S3 and the fourth rotational speed S4.

The third type of line shows the change in the regenerative recovery energy generated by the motor 3 when the torque command Tn is a negative torque output and is maintained at the first torque value T1, and the drive current Is gradually increases from the minimum drive current consistent with MPTA control. , the third type of line is marked as T1 in Figure 2. Another example As mentioned above, since different rotational speeds of the electric motor 3 will cause different regenerative recovery energy generated by the electric motor 3, the third type of lines is shown as four in Figure 2, respectively showing that the electric motor 3 maintains the first torque value under the torque command Tn. The different rotational speeds at T1 are marked in Figure 2 as the first rotational speed S1, the second rotational speed S2, the third rotational speed S3 and the fourth rotational speed S4.

The fourth type of line shows that when the torque command Tn is a negative torque output and is maintained at the second torque value T2 (assuming that the second torque value T2 is greater than the first torque value T1), and the drive current Is changes from the minimum value consistent with MPTA control When the driving current gradually increases, the regenerative recovery energy generated by the motor 3 changes. As mentioned above, since different rotational speeds of the electric motor 3 will cause different regenerative energy generated by the electric motor 3, the fourth type of lines is shown as four in Figure 2, respectively showing that the electric motor 3 maintains the torque command Tn at the second The different rotational speeds at the torque value T2 are marked as the first rotational speed S1, the second rotational speed S2, the third rotational speed S3 and the fourth rotational speed S4 in Figure 2. From the third type of lines and the fourth type of lines, it can be understood that different torque commands will cause different regenerative recovery energy generated by the electric motor 3 .

The principle of the motor drive system 1 of this case will be briefly explained below. As can be seen from Figures 2 and 3, first, when the torque command Tn received by the motor drive system 1 is a positive torque output, the motor drive system 1 will control the drive current Is received by the motor 3 based on MTPA. In addition, when the torque command Tn received by the motor drive system 1 is a negative torque output, if the motor drive system 1 controls the drive current Is received by the motor 3 based on MTPA, under normal circumstances (that is, the speed of the motor 3 is greater than the low speed threshold), the regenerative energy generated by the motor 3 will be higher than the energy loss of the motor 3, so the excess regenerative energy that cannot be offset by the energy loss of the motor 3 will be fed back to the drive circuit 4. However, If the drive current Is can be adjusted and increased from the minimum drive current consistent with MPTA control while complying with the torque command Tn, that is, as shown in Figure 3, from the minimum drive current min to, for example, special A certain driving current spec is set so that the regenerative energy of the motor 3 is equal to the energy loss of the motor 3, thereby preventing excess regenerative energy from being fed back to the drive circuit 4 from the motor 3. For example, as shown in Figure 2, when the torque command Tn is maintained at the second torque value T2 and the rotation speed of the motor 3 is the second rotation speed S2, if the drive current Is is controlled by MTPA, the corresponding first drive current value When Is_a increases to the second drive current value Is_b, the regenerative recovery energy of the motor 3 can be equal to the energy loss of the motor 3 . Based on the above principle, when the controller 2 receives the torque command Tn and outputs a negative torque, the motor drive system 1 of this embodiment allows the current command generation unit 20 to output the corresponding current command according to the zero recovery characteristic table, so as to reduce the energy loss of the motor 3 It is equal to the regenerative energy generated by motor 3.

It can be seen from the above that when the controller 2 receives the torque command Tn for negative torque output, the motor drive system 1 of this embodiment can allow the current command generating unit 20 to output the corresponding current command according to the zero recovery characteristic table, so that the motor 3 The generated regenerative recovery energy is completely suppressed by the energy loss of the motor 3. This not only increases the braking availability of the motor 3, but also reduces the wear and excessive heat energy accumulation of the mechanical brake. In addition, it also avoids the impact of the regenerative recovery energy on the motor drive system 1. Furthermore, since the motor drive system 1 does not need to install other additional devices to consume the regenerated energy, the space utilization of the motor drive system 1 is increased and the production cost is reduced.

In some embodiments, as shown in Figure 1, the motor drive system 1 further includes a secondary battery 5, the secondary battery 5 is electrically connected to the drive circuit 4, and the secondary battery 5 supplies input power to the drive circuit 4. In addition, The drive circuit 4 can also charge the secondary battery 5. When the battery voltage of the secondary battery 5 is lower than the full power diagnosis threshold, the secondary battery 5 can receive energy and perform charging operation. On the contrary, when the secondary battery 5 When the battery voltage is not lower than the full-charge diagnosis threshold, the secondary battery 5 will not perform charging operation. In addition, the controller 2 can further determine whether the battery voltage of the secondary battery 5 is lower than the full power diagnosis threshold, and/or determine whether the secondary battery 5 is abnormal. What's more, when the controller 2 receives the torque command Tn as a negative torque output and the controller 2 determines that the battery voltage of the secondary battery 5 is not lower than the full power diagnosis threshold or the secondary battery 5 is abnormal, the current command generating unit 20 is based on The zero recovery characteristic table outputs the corresponding current command so that the regenerative recovery energy generated by the motor 3 is completely suppressed by the energy loss of the motor 3 . On the contrary, when the controller 2 receives the torque command Tn for negative torque output and the battery voltage of the secondary battery 5 is lower than the full power diagnosis threshold, the current command generation unit 20 outputs the current command correspondingly according to the maximum torque table per ampere, and the controller 2. Control the driving circuit 4 to convert the regenerated energy generated by the electric motor 3 to charge the secondary battery 5.

Since the internal impedance of the motor 3 changes with temperature, in order to more accurately achieve the regenerative recovery energy generated by the motor 3 is completely suppressed by the energy loss of the motor 3 and is not affected by temperature changes, in some embodiments, as shown in No. 1 As shown in the figure, the controller 2 further includes a temperature detector 8 for detecting the ambient temperature of the motor 3, and outputting temperature information Tm to the current command generating unit 20 of the controller 2 corresponding to the detection result, in which the motor of the motor 3 The status includes temperature information Tm, and the current command generation unit 20 knows the ambient temperature of the motor 3 based on the output temperature information Tm. In addition, the zero recovery characteristic table of the current command generation unit 20 records the energy loss and regeneration recovery energy of the motor 3 Under mutual cancellation, the current command generation unit 20 converts the torque command Tn into a conversion table of current commands according to the motor state (including the rotation speed of the motor 3 and the ambient temperature of the motor 3). Therefore, the current command generation unit 20 converts the torque command Tn into a conversion table of current commands according to the zero recovery characteristic table. The corresponding current command is output, so that the regenerative recovery energy generated by the motor 3 is completely suppressed by the energy loss of the motor 3 . The zero recovery characteristic table mentioned later in this case can be that the current command generation unit 20 converts the torque command Tn into a current command according to the rotation speed of the motor 3 when the energy loss of the motor 3 and the regeneration recovery energy cancel each other out, or it can be that when the motor 3 The energy loss and regeneration recovery energy offset each other. Next, let the current command generating unit 20 convert the torque command Tn into a current command according to the rotation speed of the motor 3 and the ambient temperature of the motor 3, so no details will be described later.

It can be seen from the above that when the battery voltage of the secondary battery 5 is lower than the full-charge diagnosis threshold, the current command generation unit 20 outputs the current command correspondingly according to the maximum torque table per ampere. Therefore, the torque command Tn is a negative torque output and is given In the case of , the d-axis and q-axis current components can be optimally configured to minimize the drive current Is of the drive motor 3 to reduce the energy loss of the motor 3 . However, when the battery voltage of the secondary battery 5 is not lower than the full-charge diagnosis threshold, or the secondary battery 5 is abnormal, the secondary battery 5 can no longer be charged and the regenerative energy generated by the motor 3 is recovered. Therefore, the current command generation unit 20 corresponds to the output current command according to the zero recovery characteristic table to adjust the increase in the driving current Is, so that the energy loss of the motor 3 can be increased to be equal to the regeneration recovery energy generated by the motor 3, thereby allowing the motor 3 to generate The regeneration and recovery energy is completely suppressed by the energy loss of the electric motor 3, thereby achieving the multiple effects mentioned above.

Please refer to Figure 4, which is a system block diagram of the motor drive system of the second preferred embodiment of the present invention. The driving system 1a of this embodiment includes a motor, a driving circuit and a controller. The electric motor includes a first electric motor 30 and a second electric motor 31 . The driving circuit includes a first driving circuit 40 and a second driving circuit 41. The first driving circuit 40 converts the input power and supplies the first driving current to the corresponding first motor 30 to drive the first motor 30 and the second driving circuit 41. The driving circuit 41 converts the input power and supplies the second driving current to the corresponding second motor 31 to drive the second motor 31 . The controller includes a torque distribution unit 6, a first controller 2a and a second controller 2b. The torque distribution unit 6 receives the torque command Tn, and correspondingly distributes the first torque command Tn1 to the first controller 2a, and also distributes the second torque command Tn2 to the second controller 2b, wherein the first torque command Tn1 and the second torque command Tn2 The sum is equal to the torque command Tn. In some embodiments, the first motor 30 is a main motor, and the second motor 31 is an auxiliary motor. When the electric motor 30 cannot satisfy the torque command Tn, the torque distribution unit 6 allocates the first torque command Tn1 to the first controller 2a corresponding to the torque command Tn, and also allocates the second torque command Tn2 to the second controller 2b, so that the second The electric motor 31 operates to assist the first electric motor 30 .

In this embodiment, the operating modes and structures of the first controller 2a and the second controller 2b are similar to the controller 2 shown in Figure 1, and the operating modes and structures of the first driving circuit 40 and the second driving circuit 41 are similar. Similar to the driving circuit 4 shown in FIG. 1 , only a partial description of the operation mode and structure of the first controller 2 a , the second controller 2 b , the first driving circuit 40 and the second driving circuit 41 will be given below. The first controller 2a includes a first current command generating unit 20a. The first current command generating unit 20a outputs a first current command, where the first current command corresponds to the first torque command Tn1 received by the first controller 2a and the first The first current command includes the first d-axis current command and/or the first q-axis current command, and the first controller 2a of the controller can coordinately convert to the first drive current according to the first driving current. A d-axis current and/or a first q-axis current, and controls the first driving current of the first driving circuit 40 to approach the first d-axis current command and/or the first q-axis current command corresponding to the first current command. . The second controller 2b includes a second current command generating unit 20b. The second current command generating unit 20b outputs a second current command. The second current command corresponds to the second torque command Tn2 received by the second controller 2b and the second electric motor. 31, and the second current command includes a second d-axis current command and/or a second q-axis current command, and the second controller 2b of the controller can coordinately convert to the second d-axis current and/or the second q-axis current, and controls the second drive current of the second drive circuit 41 to approach the second d-axis current command and/or the second q-axis current command corresponding to the second current command.

In addition, the first current command generating unit 20a includes a first negative torque current characteristic table. The first negative torque current characteristic table records when the corresponding first electric motor 30 outputs negative torque according to The first motor state of the first motor 30 converts the first torque command Tn1 into a conversion lookup table of the first current command. The second current command generating unit 20b includes a second negative torque current characteristic table. The second negative torque current characteristic table records that when the corresponding second motor 31 is in negative torque output, the second motor state of the second motor 31 will be A conversion table for converting the second torque command Tn2 into the second current command.

What's more, when the first controller 2a receives the first torque command Tn1 as a negative torque output, the first current command generating unit 20a outputs the corresponding first current command according to the first negative torque current characteristic table. When the second controller 2b receives the second torque command Tn2 which is a negative torque output, the second current command generating unit 20b outputs the corresponding second current command according to the second negative torque current characteristic table.

In some embodiments, the first negative torque current characteristic table includes a first zero recovery characteristic table, which records that the energy loss of the first electric motor 30 and the regeneration recovery energy offset each other and according to the first The motor state converts the first torque command Tn1 into a conversion table of the first current command. Therefore, when the first controller 2a receives the first torque command Tn1 as a negative torque output, the first current command generating unit 20a further outputs the corresponding first zero recovery characteristic table according to the first negative torque current characteristic table. The current command is such that the energy loss of the first motor 30 is equal to the regenerated energy generated by the first motor 30 .

The second negative torque current characteristic table includes a second zero recovery characteristic table, which records that the energy loss of the second electric motor 31 and the regenerative recovery energy cancel each other out and the second torque is converted according to the state of the second electric motor. A conversion table that converts the command Tn2 into the second current command. Therefore, when the second controller 2b receives the second torque command Tn2 as a negative torque output, the second current command generating unit 20b outputs the corresponding current command according to the second zero recovery characteristic table in the second negative torque current characteristic table, so as to Let the energy loss of the second motor 31 be equal to the regenerated energy generated by the second motor 31 .

In other embodiments, the first negative torque current characteristic table includes a first regeneration recovery characteristic table, which records the corresponding characteristics of the first electric motor 30 and generates regeneration recovery energy when the negative torque is output. , and converts the first torque command Tn1 into a conversion table of the first current command according to the first motor state. In addition, the second negative torque current characteristic table further includes an energy consumption characteristic table. The energy consumption characteristic table records the characteristics of the corresponding second motor 31 and consumes energy when outputting negative torque, and changes the second motor 31 according to the state of the second motor. The second torque command is converted into a conversion table of the second current command. When the controller determines that the torque command Tn is a negative torque output, the torque distribution unit 6 distributes the first torque command Tn1 and the second torque command Tn2 corresponding to the torque command Tn, and the first current command generation unit 20a responds to the first torque command Tn1 and The first regeneration and recovery characteristic table outputs the corresponding first current command, and the second current command generating unit 20b outputs the corresponding second current command according to the second torque command Tn2 and the energy consumption characteristic table, wherein the first electric motor 30 generates regeneration and recovery energy. The energy consumption of the second electric motor 31 cancels each other out.

Please refer to Figure 5, which is a system block diagram of the motor drive system of the third preferred embodiment of the present invention. Compared with the motor drive system 1a shown in Figure 4, the motor drive system 1b of this embodiment further includes a secondary battery 5. The secondary battery 5 is electrically connected to the first drive circuit 40 and the second drive circuit 41 of the drive circuit respectively. , and the secondary battery 5 can supply input power to the first driving circuit 40 and the second driving circuit 41 respectively. In addition, the first driving circuit 40 and the second driving circuit 41 can also charge the secondary battery 5 respectively, wherein when When the battery voltage of the secondary battery 5 is lower than the full-charge diagnostic threshold, the secondary battery 5 can receive energy and perform charging operation. On the contrary, when the battery voltage of the secondary battery 5 is not lower than the full-charge diagnostic threshold or is abnormal, The secondary battery 5 does not perform charging operation.

In addition, when the controller determines that the torque command is a negative torque output, and the controller determines that the battery voltage of the secondary battery 5 is not lower than the full-charge diagnosis threshold or the secondary battery is abnormal 5, the torque distribution unit 6 distributes the third torque corresponding to the torque command. A torque command Tn1 and a second torque command Tn2, and the first current command generating unit 20a outputs the first current command according to the first torque command Tn1 and the first zero recovery characteristic table, and the second current command generating unit 20b outputs the first current command according to the second torque command Tn1. The command Tn2 and the second zero recovery characteristic table output the second current command. Therefore, under this operation, the energy loss of the first motor 30 is equal to the regenerated energy generated by the first motor 30 , and the energy loss of the second motor 31 is equal to the regenerated energy generated by the second motor 31 .

In some embodiments, the second negative torque current characteristic table of the second current command generating unit 20b further includes a second regeneration recovery characteristic table, wherein the second regeneration recovery characteristic table records the characteristics of the corresponding second electric motor 31 and Regenerative recovery energy is generated when negative torque is output, and the second torque command Tn2 is converted into a conversion table of the second current command according to the second motor state. When the controller determines that the torque command is a negative torque output and the controller determines that the battery voltage of the secondary battery 5 is lower than the full power diagnosis threshold, the torque distribution unit 6 distributes the first torque command Tn1 and the second torque command Tn2 corresponding to the torque command. , and the first current command generating unit 20a outputs the corresponding first current command according to the first torque command Tn1 and the first zero recovery characteristic table, and the second current command generating unit 20b outputs the corresponding first current command according to the second torque command Tn2 and the second regeneration recovery characteristic table. The meter outputs the corresponding second current command. Therefore, under this operation, the energy loss of the first motor 30 is equal to the regenerative energy generated by the first motor 30 , while the energy loss of the second motor 31 is less than the regenerative energy generated by the second motor 31 , and the energy loss generated by the second motor 31 is The unoffset regenerated energy can be converted through the second driving circuit 41 to charge the secondary battery 5 . In some embodiments, the second regeneration recovery characteristic table may be a maximum torque per ampere table, and the maximum torque per ampere table is based on the second regeneration recovery characteristic table. The second torque command Tn2 is converted into a second current command according to the state of the second motor 31 when the energy loss of the electric motor 31 is minimized.

In some embodiments, the second negative torque current characteristic table of the second current command generating unit 20b further includes an energy consumption characteristic table, where the energy consumption characteristic table records the characteristics of the corresponding second electric motor 31 and outputs the negative torque when the second negative torque current characteristic table is used. Energy needs to be consumed, and the second torque command Tn2 is converted into a conversion table of the second current command according to the second motor state. When the controller determines that the torque command Tn is a negative torque output and the controller determines that the secondary battery 5 is lower than the full power diagnostic threshold and can supply power normally, the torque distribution unit 6 distributes the first torque command Tn1 and the second torque corresponding to the torque command Tn. command Tn2, and the first current command generating unit 20a outputs the corresponding first current command according to the first torque command Tn1 and the first zero recovery characteristic table, and the second current command generating unit 20b outputs the corresponding first current command according to the second torque command Tn2 and the energy consumption characteristic table. Output the corresponding second current command. Therefore, under this operation, the energy loss of the first motor 30 is equal to the regenerated energy generated by the first motor 30, and the energy loss of the second motor 31 is greater than the regenerated energy generated by the second motor 31. Therefore, when the secondary battery 5 outputs When the electric energy is discharged, for example, due to improper discharge, the energy loss of the second motor 31 can offset the electric energy output by the secondary battery 5 .

In other embodiments, the first negative torque current characteristic table further includes a first regeneration recovery characteristic table, which records the corresponding characteristics of the first electric motor 30 and generates regeneration recovery when the negative torque is output. Energy, and a conversion table that converts the first torque command Tn1 into the first current command according to the first motor state. When the controller determines that the torque command Tn is a negative torque output and the controller determines that the battery voltage of the secondary battery 5 is lower than the full power diagnosis threshold and can supply power normally, the torque distribution unit 6 distributes the first torque corresponding to the torque command Tn. According to the command Tn1 and the second torque command Tn2, the first current command generating unit 20a outputs the corresponding first torque command Tn1 and the first regeneration recovery characteristic table. The second current command generating unit 20b outputs the corresponding second current command according to the second torque command Tn2 and the energy consumption characteristic table.

Please refer to Figure 6 in conjunction with Figure 5. Figure 6 is a schematic diagram of the voltage/current charging curve of the secondary battery of the motor drive system shown in Figure 5 during charging operation. In some embodiments, when the torque command Tn is a negative torque output and the secondary battery 5 is normal and performing charging operation, the secondary battery 5 will be charged according to the charging curve shown in Figure 6. To further illustrate, when When the controller of the motor drive system 1b determines that the torque command Tn is a negative torque output, the controller determines that the battery voltage Vd of the secondary battery 5 (battery voltage Vd as shown in Figure 6) is lower than the preset reference voltage range. (for example, occurs between time t0~t3) and selects the limited current charging mode for charging the secondary battery 5. In the limited current charging mode, the controller controls the driving circuit to provide the battery current Ie of the secondary battery 5 not to be higher than the predetermined value. The set reference current interval, in addition, the controller selects the limited voltage charging mode for charging the secondary battery 5 based on the battery voltage Vd of the secondary battery 5 not being lower than the reference voltage interval (for example, occurring between time t3 and t4). , in the limited voltage charging mode, the controller controls the driving circuit to provide the battery voltage Vd corresponding to the battery current Ie of the secondary battery 5 to fall within the preset reference voltage range.

In some embodiments, the reference voltage interval further includes two or more reference voltage intervals. For example, as shown in Figure 6, the reference voltage interval includes a first reference voltage interval V1 and a second reference voltage that is smaller than the first reference voltage interval V1. interval V2 and a third reference voltage interval V3 that is smaller than the second reference voltage interval V2, in which the battery voltage Vd is divided into multiple intervals based on the characteristics of the secondary battery 5 during the charging process, and The first reference voltage interval V1, the second reference voltage interval V2 and the third reference voltage interval V3 can be defined by dividing the battery voltage Vd corresponding to these intervals and adding the voltage threshold interval required for control. However, the As shown in Figure 6, these voltage threshold ranges are not shown and are simplified to a straight line. The reference current interval further includes two or more reference current intervals. For example, as shown in Figure 6, the reference current interval includes a first reference current interval I1, a second reference current interval I2 that is smaller than the first reference current interval I1, and a second reference current interval that is smaller than the second reference current interval I1. A third reference current interval I3 of the reference current interval I2, wherein the first reference voltage interval V1, the second reference voltage interval V2 and the third reference voltage interval V3 are based on protecting the secondary battery 5 during the charging process. The battery currents in each of the distinguished charging intervals plus the current threshold interval required for control can define the first reference current interval I1, the second reference current interval I2 and the third reference current interval I3. However, the sixth As shown in the figure, these current threshold intervals are not shown and are simplified to a straight line. Furthermore, the limited current charging mode further includes two or more limited current charging modes, such as a first limited current charging mode, a second limited current charging mode, and a third limited current charging mode.

In the first limited current charging mode, the controller controls the driving circuit to provide that the battery current Ie of the secondary battery 5 is not higher than the first reference current interval I1 (that is, the upper limit value of the battery current Ie of the secondary battery 5 is the first current value I1), in the second limited current charging mode, the controller controls the driving circuit to provide that the battery current Ie of the secondary battery 5 is not higher than the second reference current interval I2 (that is, the upper limit value of the battery current Ie of the secondary battery 5 is the second current value I2), in the third limited current charging mode, the controller controls the driving circuit to provide the battery current Ie of the secondary battery 5 not to be higher than the third reference current interval I3 (that is, the battery current Ie of the secondary battery 5 The upper limit value of is the third current value I3). In addition, when the controller determines that the torque command Tn is a negative torque output, the controller selects the secondary battery based on the battery voltage Vd of the secondary battery 5 being lower than the first reference voltage interval V1 and not lower than the second reference voltage interval V2. 5 is the first limited current charging mode for charging, and the controller selects the method for charging the secondary battery 5 based on the fact that the battery voltage Vd of the secondary battery 5 is lower than the second reference voltage interval V2 and not lower than the first reference voltage interval V1. In the second limited current charging mode, the controller is based on the When the battery voltage Vd of the secondary battery 5 is lower than the third reference voltage interval V3, the third current limiting charging mode for charging the secondary battery 5 is selected.

When the secondary battery 5 is normal and charging, the drive system 1b shown in Figure 5 will have multiple operating states. The first operating state is that the first torque command Tn1 completely matches the torque command Tn, and the second torque command Tn1 completely matches the torque command Tn. The command Tn2 corresponds to no torque output, that is, the second electric motor 31 does not operate, and the first electric motor 30 can generate excess regenerative electric energy and convert it through the first driving circuit 40 to charge the secondary battery 5 . The second operating state is that neither the first torque command Tn1 nor the second torque command Tn2 is zero, and the torque output corresponding to the first torque command Tn1 and the second torque command Tn2 matches the torque output corresponding to the torque command Tn. , and the first motor 30 can generate excess regenerated electric energy and convert it through the first drive circuit 40 to charge the secondary battery 5 , while the energy loss of the second motor 31 is equal to the regenerated energy generated by the second motor 31 . The third operating state is that neither the first torque command Tn1 nor the second torque command Tn2 is zero, and the torque output corresponding to the first torque command Tn1 and the second torque command Tn2 matches the torque output corresponding to the torque command Tn. , and the first electric motor 30 can generate excess regenerative electric energy and convert it through the first drive circuit 40 to charge the secondary battery 5 , and the second electric motor 31 can also generate excess regenerative electric energy and convert it through the second drive circuit 41 to charge the secondary battery 5 . Recharge the secondary battery 5. The fourth operating state is that neither the first torque command Tn1 nor the second torque command Tn2 is zero, and the torque output corresponding to the first torque command Tn1 and the second torque command Tn2 matches the torque output corresponding to the torque command Tn. , and the energy loss of the second motor 31 is greater than the regenerated energy generated by the second motor 31 , and the first motor 30 can generate excess regenerated electrical energy, and the excess regenerated electrical energy generated by the first motor 30 can be converted through the first drive circuit 40 The secondary battery 5 is charged and/or consumed by the second electric motor 31 . The operation modes of the drive system 1b in different operating states will be described below. In some embodiments, as shown in FIG. 5 , the first current command generating unit 20a A negative torque current characteristic table further includes a first regeneration recovery characteristic table, wherein the first regeneration recovery characteristic table records the corresponding characteristics of the first electric motor 30 and generates regeneration recovery energy when the negative torque is output, and according to the first electric motor 30 The state converts the first torque command Tn1 into a conversion table of the first current command. In the first operating state, that is, the torque distribution unit 6 distributes the first torque command Tn1 and the second torque command Tn2 corresponding to the torque command Tn, and the first torque command Tn1 matches the torque command Tn, and the second torque command Tn2 corresponds to none. During torque output, the first current command generating unit 20a outputs the corresponding first current command according to the first torque command Tn1 and the first regeneration recovery characteristic table. Therefore, in this first operating state, the energy loss of the first motor 30 is less than the regenerative energy generated by the first motor 30 , and the unoffset regenerative energy generated by the first motor 30 can be converted through the first driving circuit 40 And the secondary battery 5 is charged. In the first state, the regenerative energy generated by the first motor 30 makes the output power of the drive circuit comply with the limited current charging mode or the limited voltage charging mode of the secondary battery 5, so that the secondary battery 5 can comply with the charging mode shown in Figure 6 Charge according to the charging curve.

In the second operating state, that is, the torque distribution unit 6 distributes the first torque command Tn1 and the second torque command Tn2 corresponding to the torque command Tn, and the total torque output corresponding to the first torque command Tn1 and the second torque command Tn2 matches. The torque output corresponding to the torque command Tn. At this time, the first current command generating unit 20a outputs the corresponding first current command according to the first torque command Tn1 and the first regeneration recovery characteristic table, and the second current command generating unit 20b respectively outputs the corresponding first current command according to the first torque command Tn1 and the first regeneration recovery characteristic table. The second torque command Tn2 and the second current command corresponding to the second zero recovery characteristic table output. Therefore, in this second operating state, the energy loss of the first motor 30 is less than the regenerative energy generated by the first motor 30 , and the unoffset regenerative energy generated by the first motor 30 can be converted through the first driving circuit 40 When charging the secondary battery 5 , the energy loss of the second motor 31 is equal to the regenerated energy generated by the second motor 31 . In the second state, the first The regenerated energy generated by the motor 30 makes the output power of the drive circuit comply with the limited current charging mode or the limited voltage charging mode of the secondary battery 5, so that the secondary battery 5 is charged according to the charging curve shown in Figure 6.

In the third operating state, that is, the torque distribution unit 6 distributes the first torque command Tn1 and the second torque command Tn2 corresponding to the torque command Tn, and the total torque output corresponding to the first torque command Tn1 and the second torque command Tn2 matches. The torque output corresponding to the torque command Tn. At this time, the first current command generating unit 20a outputs the corresponding first current command according to the first torque command Tn1 and the first regeneration recovery characteristic table, and the second current command generating unit 20b respectively outputs the corresponding first current command according to the first torque command Tn1 and the first regeneration recovery characteristic table. The second torque command Tn2 and the second regeneration recovery characteristic table output the corresponding second current command. Therefore, in this third operating state, the energy loss of the first motor 30 is less than the regenerative energy generated by the first motor 30 , and the unoffset regenerative energy generated by the first motor 30 can be converted through the first driving circuit 40 When charging the secondary battery 5, the energy loss of the second motor 31 is less than the regeneration energy generated by the second motor 31. The unoffset regeneration energy generated by the second motor 31 can be converted through the second drive circuit 41. And the secondary battery 5 is charged. In the third state, the regenerative energy generated by the first motor 30 and the second motor 31 makes the output power of the driving circuit comply with the limited current charging mode or the limited voltage charging mode of the secondary battery 5, so that the secondary battery 5 meets the requirements. Charge according to the charging curve shown in Figure 6.

In the fourth operating state, that is, the torque distribution unit 6 distributes the first torque command Tn1 and the second torque command Tn2 corresponding to the torque command Tn, and the total torque output corresponding to the first torque command Tn1 and the second torque command Tn2 matches. The torque output corresponding to the torque command Tn. At this time, the first current command generating unit 20a outputs the corresponding first current command according to the first torque command Tn1 and the first regeneration recovery characteristic table, and the second current command generating unit 20b respectively outputs the corresponding first current command according to the first torque command Tn1 and the first regeneration recovery characteristic table. 2. Torque command and energy consumption characteristics table output Outputs the corresponding second current command. Therefore, in this fourth operating state, the energy loss of the first motor 30 is less than the regenerative energy generated by the first motor 30 , and the energy loss of the second motor 31 is greater than the regenerative energy generated by the second motor 31 , and the first motor 31 The unoffset regenerative energy generated by 30 can be converted by the first drive circuit 40 to charge the secondary battery 5 or consumed by the second motor 31 . In the fourth state, the regenerated energy of the first motor 30 offsets the energy consumption of the second motor 31, so that the output power of the drive circuit complies with the limited current charging mode or limited voltage charging mode of the secondary battery 5, so that the secondary battery 5Charge according to the charging curve shown in Figure 6.

Please refer to Figure 7 again in conjunction with Figures 5 and 6. Figure 7 is a schematic diagram of the steps of the torque distribution method of the torque distribution unit of the motor drive system shown in Figure 5. As shown in the figure, the torque distribution unit 6 of the electric motor drive system 1b will preset a reference voltage interval and a reference current, where the reference voltage falls within the reference voltage, the reference current falls within the reference current interval, and the torque distribution unit 6 executes torque The allocation method consists of the following steps.

In step S10, the torque distribution unit 6 calculates the first torque command Tn1 according to the torque command Tn. The calculation method of step S10 can be preset according to actual needs.

In step S11 , the torque distribution unit 6 determines whether the battery voltage Vd of the secondary battery 5 is greater than or equal to the reference voltage interval preset by the torque distribution unit 6 .

Step S12, when the torque distribution unit 6 determines that the battery voltage Vd of the secondary battery 5 is greater than or equal to the reference voltage, the torque distribution unit 6 increases the reference current.

In step S13, the torque distribution unit 6 determines whether the reference current is greater than the maximum charging current command. In this embodiment, the maximum charging current command will vary according to the current battery voltage Vd of the secondary battery 5. There are different values within the voltage range. When the reference current is equal to the maximum charging current command, it means that the battery current Ie provided by the drive circuit to the secondary battery 5 has reached the reference current range corresponding to the current battery voltage Vd of the secondary battery 5. Upper limit.

Step S14, when the torque distribution unit 6 determines that the reference current is greater than the maximum charging current command, the torque distribution unit 6 limits the reference current to be equal to the maximum charging current command.

In step S15 , the torque distribution unit 6 determines whether the reference current is greater than the battery current Ie of the secondary battery 5 .

Step S16, when the torque distribution unit 6 determines that the reference current is greater than the battery current Ie of the secondary battery 5, the torque distribution unit 6 increases the first torque command Tn1.

In step S17, the torque distribution unit 6 determines whether the first torque command Tn1 is greater than the torque command Tn.

Step S18, when the torque distribution unit 6 determines that the first torque command Tn1 is greater than the torque command Tn, the torque distribution unit 6 limits the first torque command Tn1 to be equal to the torque command Tn.

In step S19, the torque distribution unit 6 outputs the first torque command Tn1 to the first controller 2a.

In step S20, the torque distribution unit 6 outputs the second torque command Tn2 to the second controller 2b based on the subtraction result of the torque command Tn and the first torque command Tn1.

In step S21, when the torque distribution unit 6 determines that the battery voltage Vd of the secondary battery 5 is less than the preset reference voltage, the torque distribution unit 6 reduces the reference current and then executes step S15. In this step, the reference current can be reduced to zero.

In step S22, when the torque distribution unit 6 determines that the reference current is not greater than the battery current Ie of the secondary battery 5, the torque distribution unit 6 decreases the first torque command Tn1, and then executes step S19. In this step, the first torque command Tn1 may be reduced to zero.

In addition, when the torque distribution unit 6 determines in step S13 that the reference current is not greater than the maximum charging current command, step S15 is executed. When the torque distribution unit 6 determines in step S17 that the first torque command Tn1 is not greater than the torque command Tn, step S19 is executed.

Therefore, in order to allow the secondary battery 5 to be charged according to the charging curve shown in Figure 6 when the battery voltage Vd of the secondary battery 5 is not lower than the full-charge diagnosis threshold, the torque distribution unit 6 will be based on the voltage of the secondary battery 5. The battery voltage Vd, the battery current Ie of the secondary battery 5 and the torque command Tn are allocated to the first torque command Tn1 and the second torque command Tn2. When the battery voltage Vd is different from the reference voltage, the torque distribution unit 6 will adjust the reference current. For example, when the reference voltage is greater than the battery voltage Vd, the torque distribution unit 6 will adjust the reference current to become larger, but will not exceed the maximum charging current command. On the contrary, when the reference voltage is less than the battery voltage Vd, the torque distribution unit 6 will adjust the reference current to become smaller. When the battery current Ie is different from the reference current, the torque distribution unit 6 will adjust the first torque command Tn1. For example, when the reference current is greater than the battery current Ie, the torque distribution unit 6 will adjust the first torque command Tn1 to become larger, but not will exceed the torque command Tn. On the contrary, when the reference current is less than the battery current Ie, the torque distribution unit 6 will adjust the first torque command Tn1 to become smaller.

To sum up, this case provides a motor drive system and torque distribution method. The controller of the motor drive system cooperates with the zero recovery characteristic table of the controller to output current commands according to the torque command and the motor status of the motor to control the operation of the motor, and then The regenerative energy generated by the motor is completely suppressed by the energy loss of the motor. This not only increases the availability of the motor brake, but also reduces the wear and excessive heat energy accumulation of the mechanical brake. In addition, it also avoids the impact of the regenerative energy on the motor drive system. Moreover, since the motor drive system does not need to install other additional devices to consume regenerated energy, the space utilization of the motor drive system is increased and production costs are reduced. What's more, when the motor drive system has two motors and receives a torque command, the motor drive system controls the cooperation of the two motors so that the regenerative energy generated by the motors can recharge the secondary battery in compliance with the battery charging curve. Charging, thereby protecting the secondary battery.

1: Electric motor drive system

2:Controller

3: Electric motor

4: Drive circuit

Is: drive current

Tn: Torque command

Idcom: d-axis current command

Iqcom: q-axis current command

20:Current command generation unit

21: Speed and angle detector

22:PI controller

23:Current conversion device

24:Voltage conversion device

25: Pulse width modulation device

ω: Speed information

θ: Angle information

Ia, Ib, Ic: single-phase current

Id: d-axis current

Iq: q-axis current

Vdcom: d-axis voltage command

Vqcom: q-axis voltage command

Vabc: drive voltage command

PWM: pulse width modulation signal

8: Temperature detector

5: Secondary battery

Tm: temperature information

7: Electric vehicle system

Claims (21)

An electric motor drive system including: an electric motor; A drive circuit that converts an input power and supplies a drive current to the motor and drives the motor; and A controller further includes a current command generation unit, the current command generation unit outputs a current command corresponding to a torque command received by the controller and a motor state, the current command includes a d-axis current command and/or A q-axis current command, the controller converts it into a d-axis current and/or a q-axis current according to the drive current coordinate, and controls the drive circuit to make the drive current approach the d-axis current command corresponding to the current command. and/or the q-axis current command; Wherein, the current command generating unit further includes a maximum torque per ampere table and a zero recovery characteristic table. The maximum torque per ampere table converts the torque command into the current command according to the motor state when the energy loss of the motor is minimum. , the zero recovery characteristic table converts the torque command into the current command according to the motor state under the condition that the motor energy loss and the regeneration recovery energy cancel each other out; When the controller receives the torque command and outputs a positive torque, the current command generating unit outputs the corresponding current command according to the maximum torque table per ampere. When the controller receives the torque command and outputs a negative torque, the current command The command generating unit outputs the corresponding current command according to the zero recovery characteristic table. The motor drive system of claim 1, further comprising a secondary battery, the secondary battery supplies the input power to the drive circuit, the drive circuit is controlled by the controller, and outputs the drive current to the motor, Or charge the secondary battery; Wherein, when the controller receives the torque command as a negative torque output and the controller determines that a battery voltage of the secondary battery is not lower than a full power diagnosis threshold or the secondary battery is abnormal, the current command generating unit is based on The zero recovery characteristic table outputs the corresponding current command. The motor drive system of claim 2, wherein when the controller receives the torque command as a negative torque output and the battery voltage of the secondary battery is lower than the full power diagnostic threshold, the current command generating unit is based on The maximum torque per amp meter outputs the current command correspondingly, and the controller controls the driving circuit to charge the secondary battery. The motor drive system as described in claim 1, wherein the controller further receives a temperature information about the ambient temperature of the motor, and the zero recovery characteristic table records the different torque commands, different rotation speeds of the motor and the temperature of the motor. Under different ambient temperatures, the energy loss of the motor can be equal to the current command corresponding to the regenerative energy generated by the motor, and when the controller receives the torque command as a negative torque output, the current command generation unit The torque command, the current speed of the motor and the current ambient temperature of the motor are matched with the zero recovery characteristic table to correspondingly adjust the current command so that the regenerative recovery energy generated by the motor is completely suppressed by the energy loss of the motor, wherein the motor state includes the The current speed of the motor and the current ambient temperature of the motor. An electric motor drive system including: An electric motor, including a first electric motor and a second electric motor; A drive circuit, including a first drive circuit and a second drive circuit, respectively converts an input power and supplies a first drive current and a second drive current to the corresponding first and second motors, and respectively drive the corresponding first motor and the second motor; and A controller includes a torque distribution unit, a first controller and a second controller. The torque distribution unit receives a torque command and distributes a first torque command and a second torque command to corresponding The first controller and the second controller; the first controller and the second controller respectively further include a first current command generating unit and a second current command generating unit, the first and the second current command generating unit. The command generation unit respectively outputs a first current command and a second current command corresponding to the first and second torque commands and a first and a second motor state. The first current command includes a first d-axis current. command and/or a first q-axis current command, the second current command includes a second d-axis current command and/or a second q-axis current command, the controller corresponds to the first and the second drive The current coordinates are each converted into a d-axis current and/or a q-axis current and the corresponding first and second drive circuits are controlled so that the first and second drive currents approach the first and second drive circuits. The d-axis current and/or the q-axis current corresponding to the current command; The first and second current command generating units respectively include a first negative torque current characteristic table and a second negative torque current characteristic table, and the first and second negative torque current characteristic tables are respectively in the corresponding When the first and second electric motors are in negative torque output, the first and second torque commands are converted into the first current command and the second current command according to the states of the first and second electric motors; When the first controller receives the first torque command as a negative torque output, the first current command generating unit outputs the corresponding first current command according to the first negative torque current characteristic table; When the second controller receives the second torque command as a negative torque output, the second current command generating unit outputs the corresponding second current command according to the second negative torque current characteristic table. The motor drive system of claim 5, wherein the first and second negative torque current characteristic tables respectively include a first zero recovery characteristic table and a second zero recovery characteristic table, and the first and second zero recovery characteristic tables The recovery characteristic table corresponds to the energy loss and regeneration recovery energy of the first and second motors respectively canceling each other out and converting the first and second torque commands into the first and second torque commands according to the states of the first and second motors. one and the second current command; When the first controller receives the first torque command as a negative torque output, the first current command generating unit further outputs the corresponding third value according to the first zero recovery characteristic table in the first negative torque current characteristic table. a current command; and When the second controller receives the second torque command as a negative torque output, the second current command generating unit outputs the corresponding second current according to the second zero recovery characteristic table in the second negative torque current characteristic table. Order. The motor drive system of claim 6, further comprising a secondary battery, the secondary battery supplies the input power to the drive circuit, the drive circuit is controlled by the controller, and outputs the drive current to the motor, Or charge the secondary battery; Wherein, when the controller determines that the torque command is a negative torque output and the controller determines that a battery voltage of the secondary battery is not lower than a full power diagnosis threshold or the secondary battery is abnormal, the torque distribution unit corresponds to the The first and second torque commands are assigned to the torque command, and the first and second current command generating units respectively output corresponding values according to the first and second torque commands and the first and second zero recovery characteristic tables. the first and the second current command. The motor drive system of claim 7, wherein the second negative torque current characteristic table further includes a second regeneration recovery characteristic table, and the second regeneration recovery characteristic table is the corresponding characteristic of the second motor and is used in the negative torque current characteristic table. Regenerative recovery energy is generated during torque output, and the second torque command is converted into the second current command according to the state of the second motor; When the controller determines that the torque command is a negative torque output and the controller determines that a battery voltage of the secondary battery is lower than a full power diagnostic threshold, the torque distribution unit distributes the first and the first torque corresponding to the torque command. The second torque command, the first current command generating unit outputs the corresponding first current command according to the first torque command and the first zero recovery characteristic table, the second current command generating unit outputs the corresponding first current command according to the second torque command and the first zero recovery characteristic table. The second regeneration recovery characteristic table outputs the corresponding second current command. The motor drive system of claim 8, wherein the second regeneration recovery characteristic table is a maximum torque per ampere table, and the maximum torque per ampere table is based on the second motor when the energy loss of the second motor is minimum. The state converts the second torque command to the second current command. The motor drive system of claim 7, wherein the second negative torque current characteristic table further includes an energy consumption characteristic table, the energy consumption characteristic table corresponds to the characteristics of the second motor and is required when negative torque is output. Consume energy and convert the second torque command to the second current command according to the second motor state; When the controller determines that the torque command is a negative torque output and the controller determines that the secondary battery is lower than a full power diagnostic threshold and can supply power normally, the torque distribution unit distributes the first and the first battery in response to the torque command. The second torque command, the first current command generating unit outputs the corresponding first current command according to the first torque command and the first zero recovery characteristic table, the second current command generating unit outputs the corresponding first current command according to the second torque command and the first zero recovery characteristic table. The energy consumption characteristic table outputs the corresponding second current command. The motor drive system of claim 5, further comprising a secondary battery, the secondary battery supplies the input power to the drive circuit, the drive circuit is controlled by the controller, and outputs the drive current to the motor, Or charging the secondary battery; the first negative torque current characteristic table further includes a first regeneration recovery characteristic table, the first regeneration recovery characteristic table corresponds to the characteristics of the first electric motor and is used when the negative torque output Regenerative recovery energy is generated when the first motor state is generated, and the first torque command is converted into the first current command according to the first motor state; and the second negative torque current characteristic table further includes an energy consumption characteristic table, the energy consumption characteristic table is Corresponding to the characteristics of the second motor, energy is consumed when outputting negative torque, and the second torque command is converted into the second current command according to the state of the second motor; Wherein, when the controller determines that the torque command is a negative torque output and the controller determines that a battery voltage of the secondary battery is lower than a full-charge diagnosis threshold and can supply power normally, the torque distribution unit distributes the torque command correspondingly. The first and second torque commands are output, the first current command generating unit outputs the corresponding first current command according to the first torque command and the first regeneration recovery characteristic table, and the second current command generating unit outputs the corresponding first current command according to the first regeneration recovery characteristic table. The second torque command and the energy consumption characteristic table output the corresponding second current command. The motor drive system of claim 5, wherein the first negative torque current characteristic table further includes a first regeneration recovery characteristic table, and the first regeneration recovery characteristic table corresponds to the characteristics of the first motor and is used in the negative torque current characteristic table. Regenerative energy is generated during torque output, and the first torque command is converted into the first current command according to the first motor state; and the second negative torque current characteristic table further includes an energy consumption characteristic table, the energy consumption characteristic table The table corresponds to the characteristics of the second motor and consumes energy when outputting negative torque, and converts the second torque command into the second current command according to the state of the second motor; Wherein, when the controller determines that the torque command is a negative torque output, the torque distribution unit distributes the first and second torque commands corresponding to the torque command, and the first current command generation unit is based on the first torque command and The first regeneration recovery characteristic table outputs the corresponding first current command, and the second current command generating unit outputs the corresponding second current command according to the second torque command and the energy consumption characteristic table; Wherein, the regenerative recovery energy generated by the first electric motor and the energy consumed by the second electric motor offset each other. The motor drive system of claim 6, wherein the first controller further receives a first temperature information about the ambient temperature of the first motor, and the first zero recovery characteristic table records the first torque at different times. command, different rotation speeds of the first motor and different ambient temperatures of the first motor, the energy loss of the first motor can be equal to the first current command corresponding to the regenerative energy generated by the first motor, and the first current command The two controllers further receive a second temperature information about the ambient temperature of the second motor, and the second zero recovery characteristic table records the different second torque commands, different rotation speeds of the second motor, and the second zero recovery characteristic table. Under different ambient temperatures, the energy loss of the second motor can be equal to the second current command corresponding to the regenerative energy generated by the second motor, wherein the first motor state includes the current rotation speed of the first motor and the third A current ambient temperature of the motor, and the second motor state includes the current rotation speed of the second motor and the current ambient temperature of the second motor. The motor drive system of claim 5, further comprising a secondary battery, the secondary battery supplies the input power to the drive circuit, the drive circuit is controlled by the controller, and outputs the drive current to the motor, Or charge the secondary battery; Wherein, when the controller determines that the torque command is a negative torque output, the controller selects a limited current charging method for charging the secondary battery based on a battery voltage of the secondary battery being lower than a preset reference voltage interval. mode, and the controller selects a limited voltage charging mode for charging the secondary battery based on the battery voltage of the secondary battery not being lower than the reference voltage range; In the limited current charging mode, the controller controls the driving circuit to provide the battery current of the secondary battery not higher than the reference current interval. In the limited voltage charging mode, the controller controls the driving circuit to provide the secondary battery with a battery current not higher than the reference current interval. The battery voltage of the secondary battery is not higher than this reference voltage range. The motor drive system of claim 14, wherein the reference voltage interval further includes a first reference voltage interval and a second reference voltage interval smaller than the first reference voltage interval; the reference current interval further includes a first reference voltage interval. current interval and a second reference current interval smaller than the first reference current interval; and the limited current charging mode further includes a first limited current charging mode and a second limited current charging mode; Wherein, in the first limited current charging mode, the controller controls the drive circuit to provide the battery current of the secondary battery not higher than the first reference current range; and in the second limited current charging mode, the controller controls The driving circuit provides that the battery current of the secondary battery is not higher than the second reference current interval; Wherein, when the controller determines that the torque command is a negative torque output, the controller selects the battery voltage of the secondary battery to be lower than the first reference voltage interval and not lower than the second reference voltage interval. The first limited current charging mode of secondary battery charging; and the controller selects the second limited current charging of the secondary battery based on the battery voltage of the secondary battery being lower than the second reference voltage interval. model. The motor drive system of claim 14, wherein the first negative torque current characteristic table further includes a first regeneration recovery characteristic table, and the first regeneration recovery characteristic table corresponds to the characteristics of the first motor and is used in the negative torque current characteristic table. Regenerative recovery energy is generated during torque output, and the first torque command is converted into the first current command according to the first motor state; the torque distribution unit distributes the first and second torque commands corresponding to the torque command, and The first torque command matches the torque command, the second torque command corresponds to no torque output; and the first current command generating unit outputs the corresponding first current command according to the first torque command and the first regeneration recovery characteristic table respectively. The current command and the regenerative recovery energy generated by the first motor make the output power of the drive circuit comply with the limited current charging mode or the limited voltage charging mode of the secondary battery. The motor drive system of claim 14, wherein the first negative torque current characteristic table further includes a first regeneration recovery characteristic table, and the first regeneration recovery characteristic table corresponds to the characteristics of the first motor and is used in the negative torque current characteristic table. Regenerative recovery energy is generated during torque output, and the first torque command is converted into the first current command according to the first motor state; the second negative torque current characteristic table further includes a second zero recovery characteristic table, the second The zero recovery characteristic table corresponds to the energy loss and regeneration recovery energy of the second motor canceling each other out and converting the second torque command into the second current command according to the state of the second motor; the torque distribution unit corresponds to the torque command The first and second torque commands are allocated, and the torque output corresponding to the first torque command and the second torque command matches the torque output corresponding to the torque command; the first current command generating unit is respectively based on the The first torque command and the first regeneration recovery characteristic table output the corresponding first current command, and the second current command generating unit outputs the corresponding second current command according to the second torque command and the second zero recovery characteristic table respectively. The current command; and the regenerated energy generated by the first motor makes the output power of the drive circuit comply with the limited current charging mode or the limited voltage charging mode of the secondary battery. The electric motor drive system of claim 14, wherein the first and second negative torque current characteristic tables further include a first regeneration recovery characteristic table and a second regeneration recovery characteristic table, respectively. The regenerative recovery characteristic table corresponds to the characteristics of the first and second electric motors and generates regenerative recovery energy when negative torque is output, and the first and second torque commands are generated according to the states of the first and second electric motors. Convert to the first and second current commands; the torque distribution unit distributes the first and second torque commands corresponding to the torque command, and the torque output system corresponding to the first torque command and the second torque command Match the torque output corresponding to the torque command; and the first and second current command generating units respectively output the corresponding third current command according to the first and second torque commands and the first and second regeneration recovery characteristic tables. and the second current command; and the regenerative energy generated by the first motor and the second motor makes the output power of the drive circuit comply with the limited current charging mode or the limited voltage charging mode of the secondary battery. The motor drive system of claim 14, wherein the first negative torque current characteristic table further includes a first regeneration recovery characteristic table, and the first regeneration recovery characteristic table corresponds to the characteristics of the first motor and is used in the negative torque current characteristic table. Regenerative energy is generated during torque output, and the first torque command is converted into the first current command according to the first motor state; the second negative torque current characteristic table further includes an energy consumption characteristic table, and the energy consumption characteristic table It corresponds to the characteristics of the second motor and consumes energy when outputting negative torque, and converts the second torque command into the second current command according to the state of the second motor; the torque distribution unit distributes the torque command correspondingly The first and second torque commands are generated, and the torque output corresponding to the first torque command and the second torque command matches the torque output corresponding to the torque command; and the first current command generating unit is respectively based on the The first torque command and the first regeneration recovery characteristic table output the corresponding first current command, and the second current command generating unit outputs the corresponding second current command according to the second torque command and the energy consumption characteristic table respectively. ; And the regenerated energy of the first motor offsets the energy consumption of the second motor so that the output power of the drive circuit is consistent with the limited current charging mode or the limited voltage charging mode of the secondary battery. A torque distribution method, applied in the torque distribution unit of the controller of the electric motor drive system as in any one of claims 14-19, the torque distribution method includes the steps: (s10) Calculate the first torque command based on the torque command; (s11) Determine whether a battery voltage of the secondary battery is greater than a preset reference voltage; (s12) When the judgment result of step (s11) is that the battery voltage is greater than the reference voltage, increase the reference current; (s13) Determine whether the reference current is greater than a maximum charging current command; (s14) When the judgment result of step (s13) is that the reference current is greater than the maximum charging current command, limit the reference current to be equal to the maximum charging current command; (s15) Determine whether the reference current is greater than a battery current of the secondary battery; (s16) When the judgment result of step (s15) is that the reference current is greater than the battery current, increase the first torque command; (s17) Determine whether the first torque command is greater than the torque command; (s18) When the judgment result of step (s17) is that the first torque command is greater than the torque command, limit the first torque command to be equal to the torque command; (s19) Output the first torque command; (s20) Output the second torque command based on the subtraction result of the torque command and the first torque command; (s21) When the judgment result of step (s11) is that the battery voltage is not greater than the reference voltage, reduce the reference current and execute this step (s15); and (s22) When the judgment result of step (s15) is that the reference current is not greater than the battery current, reduce the first torque command and execute this step (s19); When the judgment result of step (s13) is that the reference current is not greater than the maximum charging current command, this step (S15) is executed. The torque distribution method of claim 20, wherein the maximum charging current command has different values according to the current voltage range of the battery voltage of the secondary battery.

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