JP2003111469A - Motor control method and control device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To stabilize drive control by suppressing fluctuations in the number of revolutions of a brushless motor when switching between an intermittent energization drive system and a 180-degree energization drive system. When switching from intermittent energization drive to 180-degree energization drive, a rotation speed control PWM duty / modulation rate calculation unit calculates a value obtained by multiplying a PWM duty of the intermittent energization drive by a predetermined value α. The corrected value is 18
A drive signal is generated as a modulation factor of the 0-degree conduction drive, and is output from the control circuit 7 to the inverter circuit 5. When switching from the 180-degree energizing drive to the intermittent energizing drive, a value obtained by multiplying the modulation factor of the 180-degree energizing drive by a predetermined value β is calculated, and the corrected value is used as the PWM duty of the intermittent energizing drive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control method and a control apparatus for driving and controlling a synchronous motor such as a brushless motor, which is composed of a rotor having a permanent magnet mounted thereon, without a position sensor.

[0002]

2. Description of the Related Art Conventionally, in sensorless operation in which a motor is drive-controlled without using a position sensor for detecting a rotor position of a brushless motor (hereinafter referred to as a motor), an energization suspension period is provided and an energization angle is less than 180 degrees. Such intermittent energization drive is generally performed. In this intermittent energization drive method, when energizing the motor coil, the induced voltage generated in the motor coil by the rotation of the motor during the energization suspension period for a certain period is detected from the motor coil terminal, and the induced voltage is applied to the motor. Determine the timing. As such an intermittent energization drive method, so-called 120-degree energization drive with an energization angle of 120 degrees is generally used.

As another drive method, there is so-called 180-degree energization drive including sine wave energization, which drives a motor without providing an energization suspension period. In the 180-degree conduction drive method, a motor induced voltage is detected by connecting a two-phase motor coil neutral point and a resistor in parallel with the two-phase coil, and comparing the voltage at this neutral point and the resistance neutral point. Then, the energization timing to the motor is determined and driven, or the motor position is detected by calculating the motor current at high speed to determine the energization timing and driven, or the phase difference between the motor drive voltage and the motor current is detected. The drive timing is determined based on

Generally, the 180-degree energization drive method is said to be a drive method with less torque fluctuation and rotation fluctuation because the drive waveform is smoother than the 120-degree energization drive method.

A method for controlling the drive of a motor by switching between these two drive systems is disclosed in Japanese Patent Laid-Open No. 10-341594. In this, the 180-degree energization drive is performed based on the output of the rotation pulse generating means such as an encoder, and when the output pulse from the rotation pulse generating means cannot be detected, the 120-degree energization drive is switched.

[0006]

However, the motor control method for switching between the two drive systems does not take into consideration fluctuations in the number of rotations at the time of switching the drive systems and reliability of energization switching. For example, the output of the motor changes due to the switching of the drive system, which in turn causes fluctuations in the number of revolutions, which causes noise and vibration. In sensorless driving,
In the transient state at the time of switching the drive, the fluctuation of the induced voltage deteriorates the rotor position detection accuracy, and the energization timing becomes unstable, which may lead to step out in the worst case.

In view of the above-mentioned problems, the present invention provides a motor control method and a control device which can stabilize the rotation speed of the motor and improve reliability when switching the drive method when different drive methods are used together. For the purpose of provision.

[0008]

According to the means for solving the problems according to the present invention, a motor for driving a load is intermittently driven by a 180-degree energization drive system in which a 180-degree energization drive is performed, and an energization pause period is provided to set a conduction angle to less than 180 degrees. This is a control method for driving and controlling a motor by selecting one of the intermittent energization driving methods for energization driving, and when changing from one driving method to the other driving method, fluctuations in the rotation speed of the motor In order to suppress it, the drive signal at the time of switching in one drive system is corrected to be the drive signal in the other drive system.

That is, when the intermittent energization drive system is switched to the 180-degree energization drive system, the drive signal in the intermittent energization drive system is corrected so as to increase the rotation speed of the motor. At this time, if switching is performed without correction, the motor rotation speed will drop too much, and it will take some time for the rotation to stabilize.However, this correction reduces the decrease in motor rotation speed immediately after switching. The target rotation speed can be reached quickly and stable rotation drive can be performed. Also, 180
When switching from the intermittent energization drive system to the intermittent energization drive system, the drive signal in the 180-degree energization drive system is corrected so as to reduce the rotation speed of the motor.

As a concrete method of correcting the drive signal, when the intermittent energization drive system is switched to the 180-degree energization drive system, the PWM duty at the time of switching in the intermittent energization drive system is corrected to be 180 in the 180-degree energization drive system.
Degree of energization modulation. Correction is 1 for PWM duty
The above predetermined value is multiplied, and this value is used as the modulation factor for 180-degree conduction. When the 180-degree energization drive system is switched to the intermittent energization drive system, the modulation factor of the 180-degree energization at the time of switching in the 180-degree energization drive system is corrected to be the PWM duty in the intermittent energization drive system. Correction is 1
The modulation factor of 80-degree conduction is multiplied by a predetermined value of 1 or less, and this value is used as the PWM duty.

The predetermined value is not limited to being uniquely limited, but may be changeable. For example, it is changed according to the energization angle of intermittent energization drive, is changed according to the rotation speed of the motor at the time of switching, is changed according to the DC voltage at the time of switching of the inverter circuit for driving the motor, and is supplied from the AC power source. Change according to the AC voltage at the time of switching.

When switching from the intermittent energization drive system to the 180-degree energization drive system, the energization phase at the time of starting the 180-degree energization drive depending on the energization mode of the intermittent energization drive at the time of switching and the rotation speed of the motor or the load state of the motor. To decide. By adjusting the energization phase at the time of switching, it is possible to perform a stable transition with an accurate energization phase, and to reliably switch the driving method.

When switching from the 180-degree energization drive system to the intermittent energization drive system, the energization phase of the 180-degree energization drive at the time of switching is determined according to the rotation speed of the motor at the time of switching or the load state of the motor. And 180 when switching
The energization mode at the time of starting the intermittent energization drive is determined according to the energization phase of the constant energization drive. Thus, the conduction phase,
By determining the energization mode, the phase information is inherited at the time of switching and a stable transition can be achieved, and the reliability of the switching control is improved.

The load state of the motor is determined by the difference between the PWM duty at the rotation speed of the motor at the time of switching and the reference PWM duty at the rotation speed, or the modulation rate at the rotation speed of the motor at the time of switching and the reference at the rotation speed. DC current supplied to the inverter circuit for driving the motor and D, which is estimated based on the difference from the modulation factor, and estimated based on the DC current supplied to the inverter circuit for driving the motor
A motor which is estimated based on the power consumption calculated from the C voltage, is estimated based on the AC current supplied from the AC power supply, is estimated based on the power consumption calculated from the AC current and the AC voltage supplied from the AC power supply, It is determined by any one of the estimation methods, such as estimating based on the motor current flowing through. Therefore, a new sensor such as a load torque detector can be eliminated, and the cost can be reduced.

After switching the driving method, switching of the driving method is prohibited for a predetermined time. As a result, it is possible to prevent the drive system from being frequently switched, so that the load on the control device can be reduced and the stress on the inverter circuit, the motor, etc. can be reduced.

After switching the drive system, acceleration / deceleration of the motor is prohibited for a predetermined time. Therefore, since it is possible to secure a time until the control after the switching is stabilized, it is possible to smoothly restart the acceleration / deceleration control.

When the rotational speed of the motor after switching is lower than the rotational speed before switching and does not reach the target rotational speed, the target rotational speed is changed to a low value. Specifically, when the rotation speed immediately after switching is smaller than the rotation speed immediately before switching and a large deviation from the target rotation speed occurs, the target rotation speed is adjusted to the low rotation speed after switching. Since the maximum rotation speed of the intermittent energization drive method is lower than the maximum rotation speed of the 180-degree conduction drive method, the rotation speed of the motor may decrease when the 180-degree conduction drive method is switched to the intermittent conduction drive method. , Control may become unstable. Therefore, if there is such a risk, by changing the target rotation speed to a low value as described above, the deviation of the rotation speed before and after the switching can be reduced, and the control can be stabilized.

It is assumed that the PWM carrier frequency is changed when the drive system is switched. As a result, the drive signal can be output at the PWM carrier frequency suitable for the switched drive system, the rotation of the motor is stable, and the drive can be performed with high efficiency and low noise.

In this case, when the 180-degree energization drive system is switched to the intermittent energization drive system, the PW of the intermittent energization drive is used.
It is assumed that the M carrier frequency is set lower than the PWM carrier frequency for 180-degree energization drive. As a result, when detecting the rotor position of the motor without a sensor, reliable position detection can be performed.

After the induced voltage generated in the motor is detected and the drive system is switched, when the induced voltage cannot be detected, the power supply to the motor is stopped. If the induced voltage cannot be detected, the rotor position cannot be known and appropriate drive control cannot be performed. At this time, by stopping the energization of the motor, it is possible to prevent the overcurrent from flowing in the inverter circuit and protect the circuit components.

As a control device for executing the above control method, a 180-degree energizing drive means for energizing and energizing a motor for driving a load by 180 degrees and an energization pause period for providing an energization angle of less than 180 degrees are intermittent. Intermittent energizing drive means for energizing and 1 depending on the state of the motor or an external command
Selection means for selecting one of the 80-degree energization driving method and the intermittent energization driving method, and one driving method for suppressing fluctuations in the rotation speed of the motor when switching from one driving method to the other driving method And a correction unit that corrects the drive signal at the time of switching to obtain the drive signal in the other drive method.

The correction means is a 180-degree drive from the intermittent energization drive system.
When switching to the 180 degree energization drive method, the value obtained by multiplying the PWM duty at the time of switching in the intermittent energization drive method by a predetermined value of 1 or more is used as the modulation rate of 180 degree energization in the 180 degree energization drive method, and the 180 degree energization drive method is intermittently changed. When switching to the energization drive system, a value obtained by multiplying the modulation rate of 180-degree energization at the time of switching in the 180-degree energization drive system by a predetermined value of 1 or less is set as the PWM duty in the intermittent energization drive system.

Further, after switching the driving method, means for prohibiting switching of the driving method for a predetermined time, means for prohibiting acceleration / deceleration of the motor for a predetermined time after switching the driving method, and generation of the motor after switching the driving method A means for stopping the energization of the motor is provided when the induced voltage that occurs cannot be detected.

[0024]

FIG. 1 shows a motor control device according to an embodiment of the present invention. In FIG. 1, the AC voltage from the AC power supply 1 is supplied to the rectifier circuit 3 via the reactor 2. The reactor 2 is inserted as a power factor correction circuit for improving the power factor reduction in the smoothing circuit 4. The rectifier circuit 3 rectifies the AC voltage into a DC voltage, and the smoothing circuit 4 smoothes the ripple component of the DC voltage. Although the full-wave rectifier circuit is used here, it may be a double voltage rectifier circuit. Further, a so-called PAM method, which is a variable power supply method that has been recently used, may be used.

The rectified DC voltage is applied to the inverter circuit 5. In the inverter circuit 5, drive elements, which are six semiconductor switching elements, are connected in a three-phase bridge shape, and the drive voltage from the inverter circuit 5 is output to the three-phase brushless motor 6.

Reference numeral 7 is a control circuit for driving and controlling the motor 6, and generally a microcomputer or DSP is used. An intermittent energization drive unit 8 controls the energization timing, a drive voltage (PWM duty) reference value, and the like for intermittent energization drive in which the motor 6 has an energization angle of less than 180 degrees and an energization pause period is provided. Is a 180-degree energizing drive section that controls energization timing, drive voltage (PWM duty) reference value setting, and the like in order to drive the motor 6 through 180-degree energization. Reference numeral 11 is a PWM for driving each drive element of the inverter circuit 5.
PWM creation / creating a signal for each drive element / each phase distribution unit, 12 is a PWM duty at the time of switching the drive system or a rotation speed control PWM duty / calculating a modulation factor /
It is a modulation rate calculation unit.

The drive system selection unit 10 selects a drive system according to the state of the motor 6 or an external instruction as to whether the motor 6 is driven intermittently or 180 degrees. The state of the motor 6 includes the number of revolutions, efficiency, load state,
There are disturbances. For example, at low speed, intermittent energization drive,
180-degree energization drive may be performed at high speed, or intermittent energization drive may be performed at light load, and 180-degree energization drive may be performed at high load. Further, the intermittent energization drive may be switched to when a disturbance occurs that makes it difficult to continue the 180-degree energization drive. Furthermore, the operator can switch the drive system by an external switch. For example, when driving at night, emphasis is placed on noise reduction, and switching is performed when 180-degree energization drive is desired.

In order to improve efficiency and suppress torque fluctuations, vibrations, and noises, it is desirable that the 180-degree energization drive be sinusoidal so that a smooth change in drive waveform can be realized. Further, the drive waveform of the intermittent energization drive may be any drive waveform as long as the energization angle is less than 180 degrees and the energization pause period is provided in the drive waveform, and the induced voltage generated during that period can be detected. For example, if the 120-degree energization drive is used, it is a complete two-phase energization and rectangular wave energization is possible, so there is an advantage that it is easy to create a drive waveform to be supplied to each phase.

The drive waveforms in each drive method are shown below. Figure 2
Is a drive waveform of a rectangular wave 120 ° energization, which is an example of intermittent energization drive, and FIG. 3 is a drive waveform of a sine wave energization, which is an example of a 180 ° energization drive. 2 and 3 are waveform diagrams showing signals for driving the drive elements of the inverter circuit 5 (PWM creation / output of each phase distribution unit 11) as analog values for each coil terminal, during an actual energization period. The PWM drive waveform is PWM-chopped at several to several tens of kHz, and the duty of the PWM drive signal is changed so as to reach the target rotation speed. By changing the duty, the voltage or current applied to the motor 6 is changed, and the rotation speed and torque are controlled.

FIG. 4 shows the procedure for controlling the rotation speed of the motor 6 at this time. When the 120-degree energization drive, which is an example of the intermittent energization drive, is selected, the control circuit 7 receives a command signal for rotating at the target rotation speed N1 in step 1 (abbreviated as S1 in the drawing), and then outputs S2. In, the rotation speed control PWM duty is set. The control circuit 7
The inverter circuit 5 is driven at the set rotation speed control PWM duty. In S3, the actual rotational speed N of the motor 6 at that time is detected. In S4, the actual rotation speed N is the target rotation speed N
It is determined whether or not it matches 1.

If they do not match, it is compared in S5 whether the current actual rotational speed N is lower or higher than the target rotational speed N1. If the actual rotation speed N is higher than the target rotation speed N1, the rotation speed control PWM duty is reduced in S6. Conversely, if the actual rotation speed N is lower than the target rotation speed N1, the rotation speed control PWM duty is increased in S7. To be done.
By repeating this operation, the rotation speed control PWM duty is adjusted, and the rotation speed control for controlling the actual rotation speed of the motor 6 according to the target rotation speed is performed.

In FIG. 5, U when 120 energization drive is selected
The inverter drive signal of a phase upper arm is shown. In the 120-degree energization drive, a PWM duty equal to the rotation speed control PWM duty is output over the entire energization section. The rest of the section is a rest period.

FIG. 6 shows the procedure for controlling the rotation speed of the motor 6 when the 180-degree energization drive is selected. The control circuit 7 is S
When a command signal for rotating at the target rotation speed N1 is given at 8, the rotation speed control modulation rate is set at step S9. The control circuit 7 drives the inverter circuit 5 at the set rotation speed control modulation rate. In S10, the actual rotational speed N of the motor 6 at that time is detected. In S11, it is determined whether the actual rotation speed N matches the target rotation speed N1.

If they do not match, it is compared in S12 whether the current actual rotational speed N is lower or higher than the target rotational speed N1. If the actual rotation speed N is higher than the target rotation speed N1, the rotation speed control modulation rate is reduced in S13. Conversely, if the actual rotation speed N is lower than the target rotation speed N1, S1 is reached.
At 4, the speed control modulation factor is increased. By repeating this operation, the rotation speed control modulation rate is adjusted, and rotation speed control for controlling the actual rotation speed of the motor 6 according to the target rotation speed is performed.

FIG. 7 shows an inverter drive signal for the U-phase upper arm when the 180-degree conduction drive is selected. In the 180-degree energization drive, the PWM duty calculated using the rotation speed control modulation rate is output so that the motor current waveform becomes sinusoidal according to the energization phase.

Here, when the drive system is switched from the 120-degree energization drive, which is an example of the intermittent energization drive, to the 180-degree energization drive, the rotation speed control PWM duty in the intermittent drive is unchanged and the rotation speed control modulation rate of the 180-degree energization drive. It is possible to use The PWM duty and the modulation rate have the same dimension.

However, in this method, an imbalance occurs between the current state of the motor 6 such as the rotation speed and the motor torque and the inverter output, and as shown by the broken line in FIG. Fluctuations may occur, and it may take some time before the actual rotation speed and the target rotation speed match. Further, if the fluctuation of the rotation speed is large, the position detection accuracy is deteriorated and, in the worst case, step-out may occur.

Therefore, when switching from the intermittent energization drive to the 180-degree energization drive, the rotation speed control PWM of the intermittent energization drive is performed.
The duty is not used as it is as the rotation speed control modulation rate of 180 degree energization, but the rotation speed control PWM duty / modulation rate calculation unit 12 outputs the predetermined value α to the PWM duty of the intermittent energization drive output from the intermittent energization drive unit 8. A value obtained by multiplying by is calculated, and the value thus corrected is output to the 180-degree energization drive unit 9 as the modulation rate for 180-degree energization drive.
The 180-degree energization drive unit 9 generates an energization voltage according to the energization timing based on this modulation rate, and outputs it to the PWM creation / phase distribution unit 11. PWM creation / phase distribution unit 11
Generates a PWM signal for each drive element and outputs the PWM signal to the inverter circuit 5 to drive the motor 6 to rotate.

As shown by the solid line in FIG. 8, the number of revolutions after switching is higher than that in the case where no correction is performed, fluctuations in the number of revolutions are small, and stable drive system switching is possible. It should be noted that the predetermined value α is set to a value preset by experiments or simulations so that fluctuations in the number of rotations at the time of switching the drive system become small.

Next, when switching from 180-degree energization drive to 120-degree energization drive, which is an example of intermittent energization drive,
A method in which the rotation speed control modulation rate of the constant current drive is directly used as the rotation speed control PWM duty of the intermittent current drive can be considered. However, even with this method, an imbalance occurs between the current motor state such as the rotation speed and the motor torque and the inverter output, and the rotation speed fluctuation occurs as shown by the broken line in FIG. It may take some time for the target speeds to match. Further, if the fluctuation of the rotation speed is large, the position detection accuracy is deteriorated and, in the worst case, step-out may occur.

Therefore, when the 180-degree energization drive is switched to the intermittent energization drive, the rotation-speed control modulation duty of the 180-degree energization drive is not used as it is as the rotation-speed control PWM duty of the intermittent drive, but the rotation-speed control PWM duty / The modulation factor calculator 12 calculates a value obtained by multiplying the modulation factor for 180-degree energization driving by a predetermined value β, and outputs the value thus corrected as a PWM duty for intermittent energization driving. The motor 6 is rotationally driven by the drive signal output from the control circuit 7 based on the PWM duty.

As shown by the solid line in FIG. 9, the number of revolutions after switching is lower than that in the case where no correction is performed, fluctuations in the number of revolutions are reduced, and stable drive system switching is possible. The predetermined value β is set to a value preset by experiments or simulations so that fluctuations in the number of rotations at the time of switching the drive system are reduced.

Regarding the predetermined values α and β, α is 1 or more and β is 1 or less. Further, the predetermined values α and β may be values according to the state of the motor 6 instead of being constant values. As a result, fine drive control can be performed, fluctuations in the rotation speed can be further reduced, and the rotation speed can be further stabilized. That is, the energization angle of the intermittent energization drive, the rotation speed of the motor 6 at the time of switching, the DC voltage at the time of switching supplied to the inverter circuit 5, the A at the time of switching supplied from the AC power supply 1.
It is a value corresponding to any of the C voltages.

For example, as shown in FIG. 10, the predetermined values α and β preset according to the energization angle of the intermittent energization drive are stored as ROM data of the control circuit 7. When the drive method is switched, the energization angle of the intermittent energization drive is detected from the intermittent energization drive unit 8 and the predetermined values α and β corresponding to the energization angle are read.

As shown in FIG. 11, the predetermined values α and β preset according to the number of revolutions of the motor 6 are set to RO of the control circuit 7.
It is stored as M data. At the time of switching the drive system, the number of rotations of the motor 6 is detected by a known number-of-rotations detection means, and predetermined values α and β corresponding to the number of rotations are read out.

Further, as shown in FIG. 12, a DC voltage detecting means 13 for detecting the DC voltage of the inverter circuit 5 is provided so that the DC voltage is inputted to the control circuit 7.
Then, as shown in FIG. 13, the predetermined values α and β corresponding to the DC voltage are stored in advance as ROM data of the control circuit 7. At the time of switching the drive system, the control circuit 7 reads out the predetermined values α and β corresponding to the DC voltage based on the DC voltage input from the DC voltage detection means 13.

Further, as shown in FIG. 14, AC voltage detecting means 14 for detecting the AC voltage applied to the rectifier circuit 3 in the preceding stage of the inverter circuit 5 is provided, and the AC voltage is input to the control circuit 7. deep. Then, as shown in FIG. 15, the control circuit 7 sets the respective predetermined values α and β according to the AC voltage in advance.
It is stored as ROM data of. At the time of switching the drive system, the control circuit 7 reads out the predetermined values α and β corresponding to the AC voltage based on the AC voltage input from the AC voltage detection means 14.

A control method for further improving the stability of rotation and the reliability of control in the above embodiment will be described below. In the intermittent energization drive, the energization mode is set to 0, 1, ..., 5,0.
・ ・ It is a method to switch in order. FIG. 16 shows an example of an energization mode in 120-degree energization drive.

Then, when the intermittent energization drive is switched to the 180-degree energization drive, the current energization phase is calculated from the energization mode at the time of switching, and the 180-degree energization drive is performed. For example,
At the switching timing from energization mode 1 to energization mode 2 in 120-degree energization drive, when switching from energization mode 1 of 120-degree energization drive to a sine wave waveform of 180-degree energization drive, the phase angle is 120 degrees. Corner 12
The sine wave data will be set using 0 degrees. However, by not using this value as it is, but adjusting the phase angle according to the rotational speed, the rotational speed fluctuation can be further reduced. For example, in the low speed range, 5 degrees is added to 125 degrees, and in the high speed range, 5 degrees is subtracted to 115 degrees.
Degree. In this way, by determining the energization phase at the time of switching the drive according to the number of rotations of the motor 6, the number of rotations of the motor 6 becomes stable, and the reliability of switching the drive system is improved.

FIG. 17 shows the motor current waveform at the time of switching from the 120-degree energization drive to the 180-degree energization drive at this time. When the drive method is switched, the phase information is inherited from the 120-degree energization drive by determining the energization phase for starting the 180-degree energization drive according to the energization mode of the 120-degree energization drive and the number of rotations at the time of switching, and the accurate energization phase is obtained. It can be seen that the transition is stable with. Further, instead of adjusting the energization phase for starting the 180-degree energization drive according to the rotation speed, the energization phase may be adjusted according to the load state of the motor 6.

Further, when the 180-degree energization drive is switched to the 120-degree energization drive, the energization mode of the 120-degree energization drive after the switching is determined according to the energization phase of the 180-degree energization drive at the time of switching. In other words, the energization phase of the 180-degree energization drive to be switched is determined according to the energization mode of the 120-degree energization drive after switching the drive method.

For example, if the 120-degree energization drive after switching the drive system is started from the energization mode 1, the energization phase of the 180-degree energization drive at the time of switching is from 60 degrees to 12 degrees.
It may be a period of 0 degree, but in the low speed range 90
And 80 degrees in a high rotation speed range, depending on the rotation speed. This improves the reliability of drive system switching.

FIG. 18 shows the motor current waveform at the time of switching from the 180-degree energization drive to the 120-degree energization drive at this time. At the time of switching the drive system, by determining the energization phase of the 180-degree energization drive to be switched according to the number of rotations of the motor 6, the phase information is inherited from the 180-degree energization drive, and a stable energization phase is achieved. I understand. Further, instead of determining the energization phase of the 180-degree energization drive for switching the drive method according to the rotation speed, it may be determined according to the load state of the motor 6.

The magnitude of the load of the motor 6 is determined by the increase amount of the rotation speed control PWM duty, that is, the value of the rotation speed control PWM duty at a certain rotation speed and the value of the rotation speed control PWM duty at the same rotation speed at the reference load. The difference between
The amount of increase in the rotational speed control modulation rate, that is, the difference between the value of the rotational speed control modulation rate at a certain rotational speed and the value of the rotational speed control modulation rate at the same rotational speed at the reference load, DC current, AC
It can be estimated from any one of current, motor current, and power consumption.

Therefore, as the load state estimating means, PW is used.
Means for calculating the amount of increase in M duty, means for calculating the amount of increase in modulation factor, and D supplied to the inverter circuit 5.
C means for detecting current, A supplied from AC power supply 1
If any one of the means for detecting the C current, the means for detecting the current flowing through the motor coil, the means for detecting the DC current and the DC voltage supplied to the inverter circuit 5 and calculating the power consumption from these is used, Good.

Similarly, another control method will be described. If the switching of the drive system occurs frequently, the load on the control circuit 7 increases, and the stress on the inverter circuit 5, the motor 6 and the like becomes excessive. Therefore, the control circuit 7 has means for prohibiting the switching of the driving method for a predetermined time after the switching of the driving method.

As a result, once the drive system is switched,
The drive system is maintained for a predetermined time, and the drive system can be switched again after the lapse of the predetermined time. Therefore, frequent switching of the drive system can be suppressed, overload of the control circuit 7 can be prevented, and stress applied to the inverter circuit 5, the motor 6 and the like can be reduced, and the life can be extended and the reliability can be improved.

Further, the drive system is switched in the transient state in which the vehicle is accelerating or decelerating toward the target rotational speed,
If acceleration or deceleration continues after switching, control stability may deteriorate. Therefore, the control circuit 7 has means for prohibiting the acceleration / deceleration of the motor 6 for a predetermined time after switching the drive system.

After the drive system is switched, the motor 6 is driven for a predetermined time at the rotation speed at the time of switching, and is accelerated / decelerated after the predetermined time has elapsed. As described above, by restarting acceleration or deceleration after waiting for stabilization of the control after switching, the load on the control circuit 7 is reduced, and the reliability of control can be improved.

Similarly, another control method will be described. Since the intermittent energization drive has the energization prohibition period, the maximum input to the motor 6 is smaller than that of the 180-degree energization drive without the energization prohibition period, and the maximum rotation speed is lower than that of the 180-degree energization drive.
Therefore, at the number of revolutions higher than the maximum number of revolutions for intermittent energization drive, 1
When the 80-degree energization drive is switched to the intermittent energization drive, the actual rotation speed after the switching is reduced to the maximum rotation speed of the intermittent energization drive, and the discrepancy with the target rotation speed becomes large. Therefore, when the 180-degree energization drive is switched to the intermittent energization drive, when the rotation speed of the motor 6 after switching is lower than the rotation speed before switching and does not reach the target rotation speed, the control circuit 7 It has a means to change the number low.

When the actual rotation speed of the motor 6 immediately after switching from the 180-degree energization drive to the intermittent energization drive decreases as compared with the actual rotation speed immediately before the switching, and the deviation from the target rotation speed exceeds a predetermined value, the target Change the rotation speed to the actual rotation speed after shifting to intermittent energization drive. As a result, there is no discrepancy between the target rotation speed and the actual rotation speed, the fluctuations in the rotation speed are quickly suppressed, and the control is stabilized. When the reduction in the actual rotation speed of the motor 6 after switching is smaller than the predetermined value, the target rotation speed is not changed.

When the efficiency and noise of the motor 6 are taken into consideration, the optimum PWM carrier frequency in 180-degree energization driving may differ from the optimum PWM carrier frequency in intermittent energization driving. Therefore, the control circuit 7
It has means for changing the PWM carrier frequency when the drive system is switched. As a result, no matter which drive method is selected, the optimum carrier frequency is obtained according to the drive method after switching, and the motor 6 can be operated with high efficiency and low noise.
Can be driven.

The load driven by the motor 6 is a compressor such as an air conditioner or a refrigerator. Since such a motor 6 is a synchronous motor unlike an induction motor, it is necessary to accurately detect the rotor position and output a drive voltage waveform signal from the inverter circuit 5 according to the position state. However, since the temperature inside the compressor is high temperature and pressure, and a sensor cannot be built in, a sensorless position detection circuit that detects the rotor position by detecting the induced voltage generated in the motor coil due to the rotation of the magnet rotor is used. ing.

This sensorless position detection circuit is roughly classified into two types, an analog type and a digital type. In the analog method, an analog filter circuit consisting of a capacitor and a resistor is inserted in the position detection input section that inputs the motor terminal voltage waveform, the waveform is shaped into a sine wave and input to the comparator, and compared with the virtual neutral point potential. The position detection signal is generated. Due to this filter circuit, the detected voltage waveform is 90 degrees out of phase with the actual induced voltage waveform.

In the digital method, the induced voltage waveform of the motor 6 is input to the comparator as it is in the form of a pulse-shaped PWM-switched waveform, and compared with a reference voltage that is ½ of the DC voltage to generate a position detection signal.

However, when the PWM waveform is turned off as in the intermittent energization drive, the induced voltage waveform does not appear when it is turned off. Therefore, processing is performed by the microcomputer in the control circuit 7 so that the position can be detected from the induced voltage waveform only when turned on. is doing. Based on the generated position detection signal, the timing for outputting the actual PWM waveform is determined, and the advance angle (field weakening) control is performed. By controlling the advance angle, high efficiency operation and expansion of the high speed range can be achieved. Moreover, since there is no filter circuit, the detection accuracy is high, there is no phase delay, and the advance angle (field weakening) control is easy. Further, the position can be detected even at low speed when the induced voltage is small, and the operation can be performed from a low rotation speed at the time of starting. As a result, the starting current can be reduced, the transistor of the inverter circuit 5 can be prevented from being damaged by an overcurrent, and the reliability can be improved.

The digital method has many advantages over the analog method, but the digital method has a disadvantage that the position can be detected only when the PWM waveform is on. Also,
The ON time of the PWM waveform changes if the carrier frequency changes even if the PWM duty is the same, and becomes longer as the carrier frequency becomes lower.

Therefore, the position can be detected in consideration of the signal transmission delay time, the position detection processing time in the microcomputer, and the like.
The control circuit 7 is arranged so as to secure the minimum on-time of the WM waveform.
Has means for setting the PWM carrier frequency of the intermittent energization drive lower than the PWM carrier frequency of the 180-degree energization drive.

Although the PWM carrier frequency is changed according to the drive system after switching, when the drive system is switched from 180 ° energization drive to intermittent energization drive, the carrier frequency for intermittent energization drive is set low. Then PWM
The on time of the waveform becomes long, and the time when position detection is possible becomes long. Therefore, the reliability of position detection can be ensured when the digital position detection circuit is used.

In the intermittent energization drive system, the energization phase is switched by detecting the induced voltage generated in the motor coil. When the 180-degree energization drive is switched to the intermittent energization drive, some time is required after the switching. When the induced voltage cannot be detected even after the lapse of time, it is considered that the rotor position is largely displaced with respect to the energization mode of the intermittent energization drive. In the worst case, the motor 6 may be locked, and an excessive current may flow through the drive element of the inverter circuit 5 to destroy the drive element. Therefore, the control circuit 7 has means for stopping energization to the motor 6 when the induced voltage cannot be detected even after a lapse of a predetermined time after switching the energization method.

If the induced voltage cannot be detected, the position cannot be detected and the normal drive control of the motor 6 cannot be performed. In such a case, the energization of the motor 6 is stopped, so that an excessive current does not flow in the inverter circuit 5, damage to drive elements such as transistors can be prevented, and drive control reliability can be improved. it can.

The present invention is not limited to the above embodiment, and it goes without saying that many modifications and changes can be made to the above embodiment within the scope of the present invention. Each of the above control methods may be used alone, or by performing a combination of arbitrary control methods,
The control performance may be further improved. Further, as the intermittent energization driving method, energization driving with an energization angle other than 120 degrees may be adopted, and the driving method may be switched between a plurality of intermittent energization driving methods and 180-degree energization driving methods.

[0073]

As is apparent from the above description, according to the present invention, when the drive system is switched between the intermittent energization drive and the 180-degree energization drive, the PWM duty which is a drive signal output to the inverter circuit or By adjusting the modulation rate, the fluctuation of the motor output can be suppressed to a small level, and the motor rotation can be stabilized and the reliability of the switching control can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a motor control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a drive waveform of intermittent energization drive.

FIG. 3 is a diagram showing a drive waveform of 180-degree conduction drive.

FIG. 4 is a flowchart showing rotation speed control of intermittent energization drive.

FIG. 5 is a diagram showing an inverter drive signal of a U-phase upper arm for intermittent energization drive.

FIG. 6 is a flowchart showing rotation speed control of 180-degree energization drive.

FIG. 7 is a diagram showing an inverter drive signal of a U-phase upper arm driven by 180 degrees conduction.

FIG. 8 is a diagram showing how the rotation speed changes when switching from intermittent energization drive to 180-degree energization drive.

FIG. 9 is a diagram showing how the rotational speed changes when switching from 180-degree energization drive to intermittent energization drive.

FIG. 10 is a diagram showing an example of PWM duty with respect to a conduction angle and predetermined values α and β for correcting a modulation rate.

FIG. 11 is a diagram showing an example of PWM duty with respect to rotation speed and predetermined values α and β for correcting a modulation rate.

FIG. 12 is a configuration diagram of a motor control device of another embodiment.

FIG. 13 is a diagram showing an example of PWM duty with respect to a DC voltage and predetermined values α and β for correcting a modulation rate.

FIG. 14 is a configuration diagram of a motor control device of another embodiment.

FIG. 15 is a diagram showing an example of PWM duty with respect to an AC voltage and predetermined values α and β for correcting a modulation rate.

FIG. 16 is a view showing a conduction mode of 120-degree conduction drive.

FIG. 17 is a diagram showing a motor current waveform when switching from intermittent energization drive to 180-degree energization drive.

FIG. 18 is a diagram showing a motor current light type at the time of switching from 180-degree conduction drive to intermittent conduction drive.

[Explanation of symbols]

1 AC power supply 2 reactor 3 rectifier circuit 4 Smoothing circuit 5 Inverter circuit 6 3-phase brushless motor 7 control circuit 8 Intermittent energizing drive 9 180 degree energizing drive 10 Drive system selection section 1l PWM creation unit / Phase distribution unit 12 RPM control PWM duty / modulation rate calculator 13 DC voltage detection means 14 AC voltage detection means

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H560 BB04 BB07 BB12 DA13 EB01                       EC01 EC02 EC07 RR10 TT12                       UA02 XA12                 5H576 BB04 BB10 CC05 DD07 EE11                       EE17 EE19 HA02 HB02 JJ02                       JJ17 LL25 MM17

Claims (30)

[Claims] 1. A motor for driving a load,
A control method for controlling the drive of a motor by selecting one of a 180-degree energization driving method for energizing the motor and an intermittent energization driving method for energizing the energization angle with a de-energization period of less than 180 degrees. Therefore, when switching from one drive system to the other drive system, the drive signal at the time of switching in one drive system should be corrected to the drive signal in the other drive system in order to suppress fluctuations in the motor speed. A method for controlling a motor. 2. When switching from the intermittent energization drive system to the 180-degree energization drive system, the drive signal in the intermittent energization drive system is corrected so as to increase the rotation speed of the motor, and the 180-degree energization drive system is switched to the intermittent energization drive system. The motor control method according to claim 1, wherein the drive signal in the 180-degree energization drive method is corrected so as to reduce the rotation speed of the motor. 3. A motor for driving a load is provided with 180
A control method for controlling the drive of a motor by selecting one of a 180-degree energization driving method for energizing the motor and an intermittent energization driving method for energizing the energization angle with a de-energization period of less than 180 degrees. Therefore, when switching from the intermittent energization drive method to the 180-degree energization drive method, the PWM duty at the time of switching in the intermittent energization drive method is corrected in order to suppress the fluctuation of the motor rotation speed, and the 180-degree energization method in the 180-degree energization drive method is corrected. A method of controlling a motor, characterized in that 4. The motor control method according to claim 3, wherein the correction is performed by using a value obtained by multiplying the PWM duty by a predetermined value of 1 or more as a modulation factor of 180-degree conduction. 5. For a motor driving a load, 180
A control method for controlling the drive of a motor by selecting one of a 180-degree energization drive method for energizing the motor and an intermittent energization drive method for energizing the energization angle with a de-energization period of less than 180 degrees. Therefore, when switching from the 180-degree energization drive system to the intermittent energization drive system, the modulation rate of the 180-degree energization at the time of switching in the 180-degree energization drive system is corrected in order to suppress fluctuations in the rotation speed of the motor.
A method of controlling a motor, characterized by using a PWM duty in an intermittent energization drive method. 6. The method of controlling a motor according to claim 5, wherein the correction is performed by using a value obtained by multiplying a modulation factor of 180-degree conduction by a predetermined value of 1 or less as a PWM duty. 7. The motor control method according to claim 4, wherein a predetermined value for correction is changed in accordance with an energization angle of the intermittent energization drive. 8. The method of controlling a motor according to claim 4, wherein a predetermined value for correction is changed according to the rotation speed of the motor at the time of switching. 9. The motor control method according to claim 4, wherein a predetermined value for correction is changed according to a DC voltage at the time of switching the inverter circuit for driving the motor. 10. A at the time of switching supplied from an AC power source
7. The motor control method according to claim 4, wherein a predetermined value for correction is changed according to the C voltage. 11. Depending on the energization mode of the intermittent energization drive at the time of switching and the rotation speed of the motor or the load state of the motor.
The motor control method according to claim 3, wherein an energization phase at the time of starting the 80-degree energization drive is determined. 12. The motor control method according to claim 5, wherein the energization phase of 180-degree energization drive at the time of switching is determined according to the rotation speed of the motor at the time of switching or the load state of the motor. 13. The method of controlling a motor according to claim 5, wherein the energization mode when starting the intermittent energization drive is determined according to the energization phase of the 180-degree energization drive at the time of switching. 14. The load condition of the motor is determined by the difference between the PWM duty at the rotation speed of the motor at the time of switching and the reference PWM duty at the rotation speed, or the modulation rate at the rotation speed of the motor at the time of switching and the rotation speed. The estimation is performed based on the difference between the reference modulation rate and the reference modulation rate.
13. The motor control method according to 1 or 12. 15. The motor control method according to claim 11, wherein the load state of the motor is estimated based on a DC current supplied to an inverter circuit that drives the motor. 16. The motor according to claim 11, wherein the load state of the motor is estimated based on power consumption calculated from a DC current and a DC voltage supplied to an inverter circuit that drives the motor. Control method. 17. The motor control method according to claim 11, wherein the load state of the motor is estimated based on an AC current supplied from an AC power source. 18. The motor control method according to claim 11, wherein the load state of the motor is estimated based on power consumption calculated from an AC current and an AC voltage supplied from an AC power source. 19. The motor control method according to claim 11, wherein the load state of the motor is estimated based on a motor current flowing through the motor. 20. The switching of the driving method is prohibited only for a predetermined time after the switching of the driving method.
7. The motor control method according to any one of 6 above. 21. The acceleration / deceleration of the motor is prohibited only for a predetermined time after the drive system is switched.
A method for controlling a motor according to any one of 1. 22. When the number of rotations of the motor after switching is lower than the number of rotations before switching and does not reach the target number of rotations,
2. The target rotation speed is changed to a low value.
The method of controlling a motor according to 2, 5, or 6. 23. The method of controlling a motor according to claim 1, wherein the PWM carrier frequency is changed when the drive system is switched. 24. The motor control method according to claim 23, wherein the PWM carrier frequency for the intermittent energization drive is set lower than the PWM carrier frequency for the 180-degree energization drive. 25. The method according to claim 1, wherein the motor is stopped from being energized when the induced voltage generated in the motor is detected and the induced voltage cannot be detected after switching the drive system. 6. A method for controlling a motor according to item 6. 26. 180 for a motor driving a load
180-degree energizing drive means for energizing electricity, intermittent energizing drive means for energizing intermittently with an energization pause period of less than 180 degrees, 180-degree energizing drive method and intermittent energizing according to the state of the motor or an external command. Selection means for selecting one of the drive methods, and when switching from one drive method to the other drive method, the drive signal at the time of switching in one drive method is corrected to suppress fluctuations in the rotation speed of the motor. Then, the motor control device is provided with a correction unit that uses the drive signal in the other drive method. 27. The correcting means is based on the intermittent energization driving method.
When switching to the 80-degree energization drive system, a value obtained by multiplying the PWM duty at the time of switching in the intermittent energization drive system by a predetermined value of 1 or more is set as a modulation factor of 180-degree energization in the 180-degree energization drive system. 7. When switching to the intermittent energization drive system, the PWM duty in the intermittent energization drive system is a value obtained by multiplying the modulation rate of the 180-degree energization at the time of switching in the 180-degree energization drive system by a predetermined value of 1 or less. 26. A motor control device according to item 26. 28. The motor control device according to claim 26, further comprising means for prohibiting the switching of the driving method for a predetermined time after the switching of the driving method. 29. The motor control device according to claim 26, further comprising means for prohibiting acceleration / deceleration of the motor for a predetermined time after switching the drive system. 30. The method according to claim 26, further comprising means for stopping energization of the motor when the induced voltage generated in the motor cannot be detected after switching the drive system.
7. The motor control device described in 7.