JP2003088181A - Power output device and control method thereof - Google Patents

Abstract

(57) [Problem] To output power from a motor using a power supply unit capable of adjusting a voltage between terminals by switching a plurality of capacitors in series / parallel, as a power source, an unintended torque is applied to the motor when the series / parallel is switched. Prevents output and outputs more stable power. A control unit includes switches SW1 to SW1.
The time constant (charge / discharge characteristic) of the smoothing capacitor 38 is calculated from the combined resistance of the power supply unit 22 and the capacitance of the smoothing capacitor 38 corresponding to the command signal for SW3, and the time constant and the command signal for the switches SW1 to SW3 are calculated. The voltage between terminals of the smoothing capacitor 38 (the potential difference acting between the positive bus 32 and the negative bus 34 of the inverter circuit 30) is estimated based on the combined voltage of the corresponding power supply unit 22, and the motor is estimated by using the estimated voltage. A PWM signal is generated such that a command torque is output from the inverter, and the PWM signal is output to the inverter circuit 30.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a power output device and a control method thereof.

[0002]

2. Description of the Related Art Conventionally, as a power output device of this type,
As a power supply unit that serves as a power supply source for an electric motor that is rotationally driven by three-phase AC power converted by an inverter circuit, a changeover switch that can switch a series-parallel connection of a plurality of capacitors and a pair of capacitors of the plurality of capacitors. There has been proposed a device including (Japanese Patent Laid-Open No. 11-215695). In this power output device, the voltage level input to the inverter circuit (potential difference acting between the positive bus and the negative bus of the inverter circuit)
By switching the series-parallel connection of the pair of capacitors according to the above, the voltage level is maintained in an appropriate state, and the efficient operation of the electric motor is attempted to be realized.

[0003]

However, in such a power output device, the voltage level changes abruptly at the time of serial / parallel switching by the changeover switch, so that the current applied to the electric motor also changes abruptly, which is not intended by the electric motor. Torque is output. In order to solve such a problem, it may be considered that the voltage level at the time of serial / parallel switching is sequentially detected by the voltage sensor and the current applied to the electric motor is controlled according to the detection result. In this case, since the voltage detected by the voltage sensor contains a high frequency component, it is necessary to remove the high frequency component with a low pass filter. Therefore, when the time constant of the low-pass filter is large with respect to the switching cycle (current control interval) of the switching element of the inverter circuit that drives the electric motor, it is not possible to cope with the sudden change in the voltage level due to the serial / parallel switching. , Unintentional torque output to the electric motor cannot be prevented.

The power output apparatus and the control method therefor of the present invention, when power is output from the electric motor using a power supply unit whose voltage can be adjusted by switching the plurality of power supply means in series and parallel, as a power supply source, the series and parallel switching is performed. One of the purposes is to prevent unintended torque output from the electric motor. Further, the power output apparatus and the control method therefor of the present invention, when the power is output from the electric motor using the power supply unit whose voltage can be adjusted by the series-parallel switching of the plurality of power supply means as the power supply source, when the series-parallel switching is performed. Also, one of the purposes is to output more stable power.

[0005]

MEANS FOR SOLVING THE PROBLEMS AND OPERATIONS AND EFFECTS THEREOF The power output apparatus and the control method thereof according to the present invention employ the following means in order to achieve at least a part of the above-mentioned objects.

A power output apparatus of the present invention is a power source having a plurality of power supply means and a switching means capable of switching between a series connection and a parallel connection of a pair of power supply means of the plurality of power supply means. A unit, an inverter circuit capable of converting electric power from the power supply unit into multi-phase AC power by switching of a switching element and outputting the multi-phase AC power, an electric motor driven by the output multi-phase AC power, and a positive bus of the inverter circuit. And a chargeable / dischargeable power storage means connected to the negative electrode bus, the storage means based on serial / parallel switching signals for the switching means, respective voltages of the plurality of power supply means, and charge / discharge characteristics of the power storage means. Voltage estimating means for estimating the voltage of the means, and the current so that a current capable of outputting the power required for the electric motor using the estimated voltage is applied to the electric motor. The switching element of the inverter circuit is summarized as further comprising a switching control means for switching control.

In the power output apparatus of the present invention, the voltage estimating means determines the voltage of the power storage means based on the serial / parallel switching signal for the switching means, the respective voltages of the plurality of power supply means, and the charge / discharge characteristics of the power storage means. Then, the switching control means performs switching control of the switching element of the inverter circuit so that a current capable of outputting the power required for the electric motor is applied to the electric motor by using the estimated voltage. This makes it possible to more accurately derive the voltage of the power storage means even when the switching means is switched in series and parallel, and use this voltage to adjust the current applied to the electric motor. As a result, it is possible to prevent an unintended torque from being output from the electric motor even when the switching means is switched between series and parallel, and more stable power can be output.

In such a power output device of the present invention,
The voltage estimating means calculates a charging / discharging characteristic of the power storage means based on an internal resistance of the power supply unit and a capacity of the power storage means according to a serial / parallel switching command to the switching means. Can also be provided. This makes it possible to more accurately calculate the charge / discharge characteristics of the power storage unit.

The control method of the power output apparatus of the present invention comprises a plurality of power supply means and a switching means capable of switching between a series connection and a parallel connection of the power supply means forming a pair among the plurality of power supply means. A power supply unit having the same, an inverter circuit capable of converting electric power from the power supply unit into multi-phase AC power by switching of a switching element and outputting the multi-phase AC power, an electric motor driven by the output multi-phase AC power, and the inverter circuit. A control method for a power output device, comprising: a chargeable / dischargeable storage means connected to a positive electrode bus and a negative electrode bus, comprising: (a) a serial / parallel switching signal for the switching means and a plurality of the power supply means. The voltage of the power storage means is estimated based on each voltage and the charge / discharge characteristics of the power storage means, and (b) the motive power required for the electric motor is output using the estimated voltage. And summarized in that the switching control of switching elements of the inverter circuit so that the ability of current is applied to the electric motor.

In the control method of the power output apparatus of the present invention, the voltage of the power storage means is estimated based on the series-parallel switching signal for the switching means, each voltage of the plurality of power supply means, and the charge / discharge characteristics of the power storage means. Then, the switching element of the inverter circuit is switching-controlled so that a current capable of outputting the power required for the electric motor is applied to the electric motor by using the estimated voltage. In this way, the voltage of the storage means can be more accurately derived even when the switching means is switched between series and parallel,
This voltage can be used to regulate the current applied to the motor. As a result, it is possible to prevent an unintended torque from being output from the electric motor even when the switching means is switched between series and parallel, and more stable power can be output.

In the power output device control method of the present invention, the step (a) is based on the internal resistance of the power supply unit and the capacity of the power storage unit in response to a signal of serial / parallel switching to the switching unit. It is also possible to include a step of calculating charge / discharge characteristics of the power storage means. This makes it possible to more accurately calculate the charge / discharge characteristics of the power storage unit.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to examples. FIG. 1 is a configuration diagram showing an outline of a configuration of a power output device 20 which is an embodiment of the present invention. As shown, the power output device 20 of the embodiment includes a plurality of capacitor banks 24 to 28 and a plurality of capacitor banks 2.
Switches SW1 to SW3 capable of switching the series connection and the parallel connection of the banks 26 and 28 which form a pair of 4 to 28.
A power supply unit 22, an inverter circuit 30 capable of converting electric power from the power supply unit 22 into three-phase AC power and outputting the power, a motor 36 rotationally driven by the output three-phase AC power, and an inverter circuit 30. Positive bus bar 3
2 and the negative electrode bus 34 and a smoothing capacitor 38 for smoothing, and a control unit 6 for controlling the entire apparatus.
With 0 and.

Each of the capacitor banks 24 to 28 constituting the power supply unit 22 is formed as a bank in which one or a plurality of capacitors (for example, electric double layer capacitors) are used as a unit. This capacitor bank 24
The switches SW1 to SW3, which can switch between the series connection and the parallel connection of the switch .about.28, turn on the switches SW1 and SW2 and turn off the switch SW3 so that the capacitor banks 26 and 28 are connected in parallel, and the switch SW.
By turning off the switches 1 and SW2 and turning on the switch SW3, the capacitor banks 26 and 28 are connected in series. This is because when the capacitor is used as a power supply source for driving the motor 36, the voltage across the terminals of the capacitor, that is, the potential difference acting between the positive bus 32 and the negative bus 34 of the inverter circuit 30 as power is received. It is based on large fluctuations. Therefore, as the capacitor banks 24 to 28 are discharged, the positive electrode bus bar 32 and the negative electrode bus bar 3 are
When the potential difference acting between the capacitor banks 4 and 4 decreases, the parallel connection is switched to the series connection state to increase the potential difference, and conversely, the positive electrode bus bar 32 is charged as the capacitor banks 24 to 28 are charged.
When the potential difference between the positive electrode busbar 34 and the negative electrode busbar 34 increases, the potential difference between the positive electrode busbar 32 and the negative electrode busbar 34 can be kept within a predetermined range by switching from serial connection to parallel connection and lowering the potential difference. It is possible to supply stable power to the motor 36.

The inverter circuit 30 is composed of six transistors T1 to T6 and six diodes D1 to D6. The six transistors T1 to T6 are arranged in pairs so as to be respectively on the source side and the sink side with respect to the positive electrode bus bar 32 and the negative electrode bus line 34, and a three-phase coil (uvw) of the motor 36 at the connection point. Are each connected. Therefore, the transistor T forming a pair in the state where the potential difference acts on the positive electrode bus 32 and the negative electrode bus 34.
By controlling the on-time ratio of 1 to T6, a rotating magnetic field can be formed in the three-phase coil of the motor 36, and the motor 36 can be driven to rotate.

The motor 36 is, for example, a PM-type synchronous generator motor capable of generating electric power, which is composed of a rotor having a permanent magnet attached to its outer surface and a stator having a three-phase coil wound thereon. The rotation shaft of the motor 36 is the output shaft of the power output device 20 of the embodiment, and power is output from this output shaft. For example, considering the case where the power output device 20 of the embodiment is mounted on a vehicle, the rotation shaft of the motor 36 is connected to the wheel axle. Further, since the motor 36 is configured as a generator motor, if power is input to the rotating shaft of the motor 36, the motor 36 can also generate power.

The control unit 60 is constructed as a microprocessor centered on a CPU 62, and is provided with a ROM 64 for storing a processing program, a RAM 66 for temporarily storing data, and an input / output port (not shown). . The control unit 60 includes bank voltages Vb1 to Vb from voltage sensors 40 to 44 that detect the voltage across the terminals of the capacitor banks 24 to 28 of the power supply unit 22.
3, the voltage Vc from the voltage sensor 46 for detecting the voltage across the smoothing capacitor 38, the input current Iin from the current sensor 48 for detecting the input current of the inverter circuit 30,
Phase currents Iu and I from current sensors 50 to 54 for detecting phase currents applied to the three-phase coils of the motor 36.
v, Iw, a rotation angle θ from a rotation angle sensor 39 attached to the rotation shaft of the motor 36, a command value for driving the motor 36, and the like are input via the input port. Further, the control unit 60 outputs a switching control signal for turning on / off the transistors T1 to T6 to the inverter circuit 30 via an output port.
Note that any one of the current sensors 50 to 54 that detect the respective phase currents applied to the three-phase coils of the motor 36 may be omitted.

Next, between the positive electrode bus bar 32 and the negative electrode bus bar 34 when switching the series / parallel of the capacitor banks 26, 28 by the operation of the power output apparatus 20 of the embodiment thus constructed, particularly the operation of the switches SW1 to SW3. A process of estimating a potential difference (hereinafter, referred to as a bus-bar voltage) that acts on the will be described. FIG. 2 is a flowchart showing an example of a busbar voltage estimation processing routine executed by the control unit 60 of the power output apparatus 20 of the embodiment. This routine is performed when a serial / parallel switching command of the capacitor banks 26 and 28 to the switches SW1 to SW3 is input.
For example, when the voltage detected by the voltage sensor 46 becomes equal to or higher than a predetermined threshold value Vh for instructing the switching of the capacitor banks 26, 28 from serial to parallel, or when the voltage detected by the voltage sensor 46 is Two
Predetermined threshold value V for instructing switching from 8 in parallel to in series
Every time a predetermined time (for example, 2)
It is repeatedly executed (every 00 μsec).

When the bus line voltage estimation processing routine is executed, the CPU 62 of the control unit 60 first reads the on / off command signals for the switches SW1 to SW3 and the bank voltages Vb1 to Vb3 of the capacitor banks 24 to 28 (step S100). ), Each bank voltage Vb1 to Vb
3, the combined voltage Vb of the power supply unit 22 corresponding to the on / off command signals of the switches SW1 to SW3 is calculated, and the capacitor bank 24 is derived in advance by experiments or the like.
28 internal resistors Rb1 to Rb3 to switches SW1 to
Power supply unit 22 corresponding to ON / OFF command signal of SW3
A process of calculating the combined resistance Rb of the above is performed (step S1).
02). In this process, when a command signal for turning off both the switches SW1 and SW2 and turning on the switch SW2 is input, the capacitor banks 26 and 28 are switched from parallel connection to series connection. The combined voltage V and the combined resistance R are expressed by the following equation (1),
It can be calculated using (2).

Vb = Vb1 + Vb2 + Vb3 (1) Rb = Rb1 + Rb2 + Rb3 (2)

On the other hand, when the command signal for turning on both the switches SW1 and SW2 and turning off the switch SW2 is input, the capacitor banks 26 and 28 are switched from the series connection to the parallel connection. The combined voltage V and the combined resistance R can be calculated using the following equations (3) (or (4)) and (5).

[0021]   Vb = Vb1 + Vb2 (3)   Vb = Vb1 + Vb3 (4)   Rb = Rb1 + Rb2 · Rb3 / (Rb2 + Rb3) (5)

When the combined voltage Vb and combined resistance Rb of the power supply unit 22 are calculated, the combined resistance Rb of the power supply unit 22 is multiplied by the electrostatic capacity C of the smoothing capacitor 38 stored in the ROM 64 or the like in advance to obtain a smoothing capacitor. The time constant τ as the charge / discharge characteristic of No. 38 is calculated (step S10).
4). Then, the voltage between terminals of the smoothing capacitor 38, that is, the voltage V (t) between buses is estimated using the following equation (6) (step S106), and this routine is finished. Here, the inter-bus voltage V (t-1) is the inter-bus voltage calculated in the previous routine, and is input as an initial value from the voltage sensor 46 via the low-pass filter every predetermined time (for example, 20 msec). Voltage value is used. Note that Δ is the execution time interval of this routine (for example,
The above is 200 μsec).

[0023]   V (t) = (1-Δ / τ) V (t-1) + (Δ / τ) Vb (6)

When the inter-bus voltage V (t) is thus estimated, the motor 36 is estimated using the estimated inter-bus voltage V (t).
Drive control is performed. The drive control of the motor 36 is performed by executing a motor control routine illustrated in FIG.

When this motor control routine is executed,
The CPU 62 of the control unit 60 first determines the voltage V between the buses.
(T) and processing for reading various data such as the phase currents Iu, Iv, Iw flowing in the three-phase coils of the motor 36 and the command dq currents Id *, Iq * corresponding to the torque command value of the motor 36. Execute (step S200). When the routine of FIG. 2 is not executed, the voltage V (t) between the bus lines is set every predetermined time (for example, every 10 msec).
The voltage input from the voltage sensor 46 via the low-pass filter is used as the input voltage. Then, the read phase current I
u, Iv, and Iw are subjected to three-phase to two-phase conversion, and dq currents Id and I
q is calculated (step S202), and this dq current I
Deviations ΔId and ΔIq between d and Iq and the command dq currents Id * and Iq * read in step S200 are calculated (step S204). Then, the command dq voltage Vd
* And Vq * are calculated using the following equations (7) and (8) (step S206). Here, KPD and KPQ are gains in the proportional term, and KID and KIQ are gains in the integral term.

[0026] Vd * = KPDΔId + KID∫ΔIddt (7) Vq * = KPQΔIq + KIQ∫ΔIqdt (8)

When the command dq voltages Vd *, Vq * are calculated, the command voltages Vu *, Vu *,
Calculated as Vv * and Vw * (step S208), and the inter-bus voltage V (t) read in step S200.
And by using the following equations (9), (10), (11)
M conversion, that is, the on-time ratios PWMu, PWMv, and PWMw of each pair of the transistors T1 to T6 are set (step S210), and the PWM signal is supplied to the transistor T1 of the inverter circuit 30 so that the set on-time ratio is achieved. To T6 (step S212), and this routine ends. Note that PWMu, PWMv, and PWMw are
The value 1 is set within the range of values 0 to 1 with the on-time ratio of 100%.

[0028] PWMu = 0.5 + Vu * / V (t) (9) PWMv = 0.5 + Vv * / V (t) (10) PWmw = 0.5 + Vw * / V (t) (11)

As a result, the inverter circuit 30 which receives the PWM signal rotationally drives the motor 36 by turning on / off the transistors T1 to T6, and the power output device 20 of the embodiment is shown.
Power is output to the output shaft of.

FIG. 4 is a diagram showing a waveform of a current applied to the motor 36 when the capacitor banks 26 and 28 are switched from parallel to series without considering the charging / discharging characteristics of the smoothing capacitor 38. Is the capacitor banks 26, 2 in consideration of the charge / discharge characteristics of the smoothing capacitor 38.
It is a figure which shows the electric current waveform applied to the motor 36 at the time of switching from 8 parallel to series. 4 (a) and 5 (a) show current waveforms on the dq axes, and FIG.
FIG. 5B and FIG. 5B show current waveforms in the u phase of the three-phase coil of the motor 36. As shown in FIGS. 4A and 4B, when the charge / discharge characteristics of the capacitor are not considered,
The current Iq (torque) flowing through the q-axis does not match the command current Iq * (torque command), and the capacitor bank 26,
It can be seen that the motor 36 outputs an unintended torque because it cannot respond to a rapid change in the voltage across the smoothing capacitor 38 (voltage between the busbars) when switching from parallel to series of 28. On the other hand, when considering the charge / discharge characteristics of the capacitor, that is, when estimating the terminal voltage of the smoothing capacitor 38 based on the charge / discharge characteristics of the smoothing capacitor 38 as shown in FIG. , The current Iq (torque) flowing in the q-axis is the command current I
q * (torque command) is almost the same, and the motor 36 does not operate even when the voltage across the smoothing capacitor 38 changes rapidly.
It can be seen from the output that the torque according to the command torque is being output.

According to the power output apparatus 20 of the embodiment described above, the terminal voltage of the smoothing capacitor 38 is estimated based on the charge / discharge characteristics of the smoothing capacitor 38 when the capacitor banks 26, 28 are switched in series / parallel. Since the motor 36 is drive-controlled using this estimated voltage, it is possible to prevent the unintended torque from being output to the motor 36 and drive the motor 36 more appropriately. As a result, stable operation of the power output device 20 can be ensured.
Further, when the power output device 20 of the embodiment is mounted on a vehicle, it is possible to secure a good ride comfort of the vehicle.

In the power output device 20 of the embodiment, the motor 36 driven by the three-phase AC power is used as the electric motor, but any type of motor driven by the multi-phase AC power may be used.

Although the embodiments of the present invention have been described with reference to the embodiments, the present invention is not limited to the embodiments of the present invention, and various embodiments are possible without departing from the gist of the present invention. Of course, it can be implemented in.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of a configuration of a power output device 20 which is an embodiment of the present invention.

FIG. 2 is a control unit 6 of the power output device 20 according to the embodiment.
6 is a flowchart showing an example of a bus line voltage estimation processing routine executed by 0.

FIG. 3 is a control unit 6 of the power output device 20 according to the embodiment.
6 is a flowchart showing an example of a motor control routine executed by 0.

FIG. 4 is a diagram showing a waveform of a current applied to the motor 36 when the capacitor banks 26 and 28 are switched from parallel to series without considering the charge / discharge characteristics of the smoothing capacitor 38.

5 is a diagram showing a waveform of a current applied to the motor 36 when the capacitor banks 26 and 28 are switched from parallel to series in consideration of the charging / discharging characteristics of the smoothing capacitor 38. FIG.

6 is a diagram showing an example of an estimated voltage waveform based on the charge / discharge characteristics of the smoothing capacitor 38. FIG.

[Explanation of symbols]

20 power output device, 22 power supply unit, 24, 2
6,28 capacitor bank, 30 inverter circuit,
32 positive bus, 34 negative bus, 36 motor, 38
Smoothing condenser, 39 rotation angle sensor, 40, 42,
44,46 voltage sensor, 48,50,52,54 current sensor, 60 control unit, 62 CPU, 64
ROM, 66 RAM, SW1 to SW3 switches, T
1 to T6 transistors, D1 to D6 diodes.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5H115 PA00 PC06 PG04 PI11 PI21                       PI29 PU10 PV09 PV23 RB22                       RB26 SE04 TO12 TO13                 5H576 AA15 BB08 BB10 CC06 CC09                       DD07 EE01 EE11 EE21 HA02                       HB01 LL22 LL24

Claims (4)

[Claims] 1. A power supply unit having a plurality of power supply means and a switching means capable of switching series connection and parallel connection of a pair of power supply means of the plurality of power supply means, and the power supply unit. An inverter circuit capable of converting the electric power from the electric power into a multi-phase AC power by switching of a switching element and outputting the multi-phase AC power, an electric motor driven by the output poly-phase AC power, and a positive bus and a negative bus of the inverter circuit. The charging / discharging power storage means, the serial / parallel switching signal for the switching means, the respective voltages of the plurality of power supply means, and the charging / discharging characteristics of the power storage means to estimate the voltage of the power storage means. Voltage estimating means, and a switch of the inverter circuit so that a current capable of outputting power required for the electric motor using the estimated voltage is applied to the electric motor. Power output apparatus and a switching control means for switching control of the ring element. 2. The voltage estimating means calculates a charge / discharge characteristic of the power storage means based on an internal resistance of the power supply unit and a capacity of the power storage means according to a series-parallel switching command to the switching means. The power output device according to claim 1, further comprising charge / discharge characteristic calculation means. 3. A power supply unit having a plurality of power supply means and a switching means capable of switching series connection and parallel connection of a pair of power supply means of the plurality of power supply means; Connected to a positive-current bus and a negative-bus of the inverter circuit, an inverter circuit capable of converting and outputting the electric power of the electric power to multi-phase AC power by switching of a switching element, an electric motor driven by the output multi-phase AC power. A method of controlling a power output device, comprising: a chargeable / dischargeable power storage means, comprising: (a) a serial / parallel switching signal for the switching means, each voltage of the plurality of power supply means, and charging / discharging of the power storage means. The voltage of the storage means is estimated based on the characteristics, and (b) a current capable of outputting the power required for the electric motor is applied to the electric motor by using the estimated voltage. The method of power output apparatus for switching control of the switching elements of the Hare said inverter circuit. 4. The step (a) calculates a charge / discharge characteristic of the power storage unit based on an internal resistance of the power supply unit and a capacity of the power storage unit according to a series-parallel switching signal to the switching unit. 4. The step of:
A method for controlling the power output device described.