JP3472533B2 - Motor control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor and a switch reluctance (SR) which estimates a rotation angle of a rotor from a low-resolution rotation position signal and supplies a current or a voltage that changes with an arbitrary waveform to a stator winding. The present invention relates to a control device such as a motor.

[0002]

2. Description of the Related Art In order to drive and control a brushless motor or a reluctance motor without a commutator such as a commutator or a brush, it is necessary to accurately detect the position of a rotating rotor. 2. Description of the Related Art As a conventional motor control device, there is one called a 120-degree conduction rectangular wave drive system that drives based on a low-resolution rotational position signal. In this motor control method, power is supplied to the stator windings by a rectangular wave voltage, so the current flowing in the stator windings is greatly distorted, and the change in current during on / off becomes large, resulting in pulsation of the generated torque. Was large and was a cause of vibration and noise of the motor.

To solve this, for example, a control method for estimating the rotation angle of a rotor in a brushless motor and supplying a voltage that changes in a substantially sinusoidal waveform, or SR
There is a control method that estimates the rotation angle of the rotor in the motor and supplies a current that changes in a trapezoidal waveform.

A method of estimating the rotor angle is disclosed in, for example, Japanese Patent Laid-Open No. 11-215881. The time interval of the signal edge of the position detection signal for detecting the rotational position of the rotor is measured by the pulse counter of the CPU or the like, and the angle update amount per pulse is calculated from the count number. Then, by adding the angle update amount calculated for each pulse to the current estimated angle (electrical angle), the resolution can be increased up to the time period of one pulse. However, due to the acceleration / deceleration of the motor, a deviation occurs between the absolute angle obtained from the position detection signal and the estimated angle. Therefore, the angle update amount calculated above is corrected by an appropriate correction gain to prevent the deviation amount from accumulating.

That is, as shown in FIG. 6, the absolute angle 0
Between 60 and 60 degrees, the number of measured pulses between the signal edges is 6, and the angle update amount before this is 10 degrees per pulse. Therefore, the current estimated angle is created by adding 10 degrees for each pulse to the estimated angle of 60 degrees. Then, at the next signal edge, the absolute angle is 1
Even though it is 20 degrees, the estimated angle is 12 due to acceleration.
It does not reach 0 degrees. For example, it may be 100 degrees. At this time, the deviation of 20 degrees must be corrected.

First, the pulse count number from 60 degrees to 120 degrees is 4 pulses, and the angle update amount is 15 degrees. The deviation correction amount per pulse is 20 degrees * (correction gain) = 20 degrees × 0.5 = 10 degrees, which is 25 degrees (= 15 degrees +) based on this and the angle update amount.
10 degrees) is added to the estimated angle for each pulse to create the current estimated angle.

[0007]

In the angle estimation method disclosed in the above publication, the correction gain for deviation correction can be set according to the magnitude of acceleration. However, when the correction gain is set to a large value, the estimated angle error increases due to overshoot of the shift correction, which causes a motor torque ripple and causes a sharp change in the angle. Change drastically, causing vibration and noise of the motor.

In view of the above, it is an object of the present invention to provide a motor control device capable of reducing the estimated angle error and suppressing abrupt changes in the voltage and current supplied during deviation correction.

[0009]

A means for solving the problems according to the present invention is a counting means for measuring a time interval of a detection signal output from a position detecting means for detecting a rotational position of a rotor based on a clock signal, and the detecting means. The update amount calculation means for calculating the angle update amount based on the count number obtained by the counting means from the rotation angle between the signals, and the angle update amount for the estimated angle which is the estimated value of the rotation angle of the rotor are added. An estimated angle creating unit that creates a current estimated angle and a deviation angle between the actual rotation angle obtained by the detection signal of the position detection unit and the estimated angle when the detection signal is output during the acceleration / deceleration operation of the motor. Deviation calculation means,
The correction means is provided for performing a stepwise correction of the deviation angle with respect to the current estimated angle.

By using the pulse signal of the constant cycle of the counting means, the estimated angular resolution can be set smaller than the angular resolution that can be detected by the position detecting means. This makes it possible to create the estimated angle in fine steps. Then, a deviation angle is obtained from the actual rotation angle detected by the position detection means and the estimated angle when the rotation angle is detected, and the deviation correction amount is calculated by multiplying the deviation angle by a correction gain. The current estimated angle is corrected by adding it to the angle update amount. At this time, since the deviation correction amount is added the number of times determined according to the correction gain,
The shift correction is performed stepwise by the shift angle, and the estimated angle error can be reduced.

A drive command signal to the stator winding is output based on the thus-estimated estimated angle with a small error, and a current or voltage is supplied to the stator winding.
Therefore, by performing a fine shift correction, it is possible to eliminate a sudden change in the estimated angle, and it is possible to suppress a sudden change in the voltage or current supplied for driving the motor. In particular, this is a suitable correction method for correcting the deviation during acceleration / deceleration of the motor.

To create the estimated angle with higher accuracy,
It is preferable to provide a gain adjusting means for setting a correction gain according to the acceleration. That is, during acceleration and deceleration, the angle deviation with a change in the rotational speed of the rotor varies, when the acceleration is large set small correction gain, the larger set the correction gain when the acceleration is small, not the angle change is large The fine deviation correction can be performed according to the change of the rotation angle, and the estimated angle error can be further reduced.

Further, since the rotation speed of the motor changes during acceleration / deceleration, it is advisable to provide a correction timing switching means for switching the timing for correcting the deviation according to the rotation speed of the motor. When the time interval between the detection signals decreases as the rotation speed increases, the misalignment correction control can be executed at a substantially constant interval regardless of the rotation speed by switching so that the angular interval of the misalignment correction timing increases. The load on the control device can be reduced.

The rotation speed when switching the timing is set to be different from the rotation speed corresponding to the mechanical resonance frequency of the motor. Further, hysteresis is provided so that the rotation speed when switching during acceleration is higher than the rotation speed when switching during deceleration. By doing so, stability at the time of switching can be achieved.

Then, in order to perform drive control so as to avoid a sudden change in the current or voltage supplied to the stator winding, the deviation correction section is set in accordance with the timing when the change in the drive command signal waveform becomes gentle. To do. Here, with respect to the setting of the deviation correction section, the position detection means is installed so that the detection signal is output in accordance with the rotation angle at which the change of the drive command signal waveform becomes gentle. Alternatively, the shift correction timing is delayed by a timer or the like so that the shift correction is performed when the rotation angle advances by a predetermined angle from the time when the detection signal is generated. With this, the deviation correction is performed when the waveform change of the current or the voltage is small, so that it is possible to prevent the change of the current or the voltage from increasing even if the estimated angle greatly changes due to the deviation correction.

Alternatively, gain changing means for changing the correction gain in accordance with the degree of change of the drive command signal waveform may be provided. That is, if the position detection signal is generated in a region where the change of the signal waveform is large, the correction gain is reduced. Can prevent a large change in.

Therefore, when the deviation correction is performed when the waveform change of the current or voltage supplied to the stator winding is small,
Even if the correction gain is increased, its effect can be minimized, and the overshoot of the correction angle is eliminated, so that the occurrence of torque ripple, vibration of the motor, and noise can be eliminated.

[0018]

FIG. 1 shows a motor control device for a brushless motor according to an embodiment of the present invention. The motor control device obtains the deviation angle between the position detector 1 including a Hall element or the like for detecting the rotational position of the rotor and the estimated angle from the rotation angle based on the position detection signal from the position detector 1, and calculates the deviation correction amount. Deviation angle / speed measuring device 2 that calculates the actual rotation speed and rotation acceleration from the rotation angle and an angle counter 3 that creates an estimated angle that has been corrected for deviation by the deviation angle. Drive circuit 4 for generating a drive command signal to the stator windings in accordance with the estimated angle of 1 and a CPU (not shown) for driving and controlling the drive circuit 4 to correct the deviation and control the motor drive.

The deviation angle / velocity measuring device 2 measures the time interval between the signal edges of the detection signal output from the position detector 1 by utilizing the clock signal at a constant interval output from the timer of the CPU. , Get the pulse count number. Then, based on this count number, the angle update amount is calculated from the rotation angle between the signal edges.

In the angle count 3, the current estimated angle is created for each pulse by adding the deviation correction amount calculated from the deviation angle and the correction gain set by the CPU to the angle update amount, and the driving circuit 4 is caused to do so. Output. The drive circuit 4 is composed of a PWM signal generator, an inverter circuit, etc., and creates a three-phase sinusoidal drive command signal or a trapezoidal drive command signal from the estimated angle, and the PWM control is proportional to the drive command signal. A sinusoidal excitation current or a trapezoidal excitation current is output, and this excitation current is supplied to the stator winding. Further, the number of times the deviation correction amount is added is determined by the correction gain, and the number is the reciprocal of the correction gain, and the total deviation correction amount becomes the deviation angle. In the figure, Δθ is the deviation correction amount, θupdate is the angle update amount,
θc is an estimated angle and K is a correction gain.

The deviation correction method will be described in detail with reference to FIG.
As shown in, when the absolute angle, which is the actual rotation angle during acceleration, is between 0 and 60 degrees, the number of measurement pulses between signal edges is 6, so the angle update amount is 10 degrees per pulse. Become. Therefore, the current estimated angle is created by adding 10 degrees for each pulse to the estimated angle of 60 degrees. And the next signal edge has an absolute angle of 1
It occurs at 20 degrees, but the estimated angle does not reach 120 degrees because of acceleration. For example, it may be 100 degrees, and the shift angle is 20 degrees.

At this time, the rotation angle between the signal edges is 60.
Since the number of degrees and count is 4 pulses, the angle update amount is 1
It will be 5 degrees. If the correction gain is 0.5, the deviation correction amount per pulse is 20 degrees * (correction gain) = 20 degrees × 0.5 = 10 degrees. Further, since the deviation correction amount per pulse is 10 degrees, the deviation angle corresponds to two pulses, and the deviation correction corresponding to the deviation angle can be performed by updating the angle twice.

Then, 25 degrees, which is the sum of the deviation correction amount and the angle update amount, is added to the estimated angle to perform the first angle update. As the second angle update according to the next pulse,
Similar to the above, the deviation is corrected by adding the deviation correction amount to the updated estimated angle. With these two angle updates,
The deviation correction amount reaches the deviation angle, and the deviation correction is completed. It is not necessary to consider the deviation correction amount in the third and subsequent angle updates, and only the angle update amount of 15 degrees is added to the estimated angle. In addition, even during deceleration, the deviation correction is similarly performed.

Therefore, the estimated angle error can be minimized by performing the correction for the shift angle stepwise during acceleration / deceleration. Moreover, since the estimated angle does not change abruptly during the deviation correction, it is possible to suppress the abrupt change in the voltage or current supplied to the stator winding based on the estimated angle. Further, even when the correction gain is set to a large value, it is possible to prevent the overshoot of the deviation correction and prevent the occurrence of the torque ripple of the motor.

By the way, since the rotational speed (rotation speed) of the rotor changes during acceleration / deceleration, the deviation angle also changes accordingly. Therefore, since the acceleration of the rotor can be detected by measuring the time interval between the signal edges, the CPU may be provided with a gain adjusting function for setting a correction gain according to the acceleration. For example, set low and the correction gain when the acceleration is large, large sets a correction gain when the acceleration is small. As a result, fine shift correction can be performed according to changes in the rotation angle, the estimated angle error can be further reduced, and the rotation angle can be estimated with high accuracy.

Further, when the rotation speed (rotation speed) is high, the time interval between the signal edges becomes small, and the shift correction C is performed.
The burden on the PU increases. Therefore, control is performed such that the timing for performing the deviation correction is switched according to the rotation speed. That is, as shown in FIG. 3, when starting the operation and accelerating, deviation correction is performed every 60 degrees up to 100 rpm, and every 1000 degrees over 1000 rpm up to 100 rpm over 1000 rpm.
Every 6 rotations (2160 degrees) up to 10000r
When it exceeds pm, the deviation is corrected every 36 rotations (12960 degrees).

As described above, since the time interval between the signal edges becomes smaller as the rotation speed increases, the rotation speed of the rotor is increased in the CPU by switching the timing interval for correcting the deviation so as to be larger. Can also perform the shift correction control at substantially constant intervals, and C
The burden on the PU can be reduced.

At this time, when setting the number of revolutions for switching the timing of deviation correction, it may be set so as to be different from the mechanical resonance frequency of the motor. In this way, by avoiding the resonance frequency in setting the rotation speed,
The unstable state of the motor at the time of switching can be avoided.

Similarly, the switching timing may be changed during deceleration. However, since the change in the rotational speed differs between during acceleration and during deceleration, a hysteresis is provided in the rotational speed for switching the timing of deviation correction. deep. That is, if the rotation speed is set to be higher than that during deceleration during acceleration, such as switching at 100 rpm during acceleration and switching at 80 rpm during deceleration, simple vibration is prevented from occurring in the rotation speed of the motor during switching. It is possible to achieve stability when switching.

The above-mentioned motor control device is suitable for controlling the motor of the washing machine, and in particular, when it is applied to the correction of the deviation of the rotation angle at the time of starting and stopping the rotation of the spin-drying operation, the torque can be corrected. The pulsation of can be suppressed. Further, it is possible to avoid unstable behavior when switching the angular interval for performing the deviation correction, and suppress the generation of vibration and noise.

Next, a drive command signal to the stator winding is created based on the estimated angle corrected for deviation, and an exciting current is supplied to the stator winding. Here, in order to control the drive so that the waveform of the current flowing through the stator winding does not change abruptly, the deviation correction section is set. For example, since the SR motor is supplied with a three-phase trapezoidal current, it is controlled so as to correct the deviation when the change in the current waveform is small.

FIG. 4 shows the current command values for the A, B, and C phases of the motor during steady operation with no estimated angle error. The resolution of the position detection signal from the position detector 1 is 120 degrees. Here, when an estimated angle error occurs during acceleration, the deviation correction is performed after the signal edge appears.
As shown in FIG. 6, if a signal edge is output when the energized phase is switched, the current waveform changes drastically in this deviation correction section. In particular, when the correction gain is large, the current waveform changes more rapidly, which causes vibration of the motor.

Therefore, when the change of the current waveform becomes gentle, that is, in the top flat region of the current waveform,
The position detector 1 may be attached so as to generate the position detection signal. That is, if the phase of the command current is constant,
Since it is possible to know in advance which rotation angle is the top flat region, the mounting position of the position detector 1 can be adjusted so that the rotation angle corresponding to the top flat region can be detected at the design stage. Therefore, when the signal edge from the position detection signal occurs, the change in the current waveform is small, and if the deviation correction is performed at this time, the change in the supplied current can be prevented from increasing even if the correction gain is increased.

However, when it is difficult to adjust the generation angle of the signal edge of the position detector 1 at the design stage,
It cannot be installed as described above. Further, when the phase of the current waveform changes, the area where the current waveform changes little also changes, but it is impossible to change the mounting position of the position detector 1 during the operation of the motor accordingly. . In such a case, the deviation is not corrected immediately after the signal edge is generated, but is delayed by a timer or the like so that the deviation correction section extends to the top flat area. That is, after the signal edge occurs, update the angle as needed,
When the estimated angle reaches the top flat region, the deviation correction is performed. As a result, the deviation correction can be performed in accordance with the timing at which the current waveform changes gradually, and it is possible to prevent the current change from increasing due to the deviation correction.

As another method, the correction gain may be changed according to the degree of change in the current waveform.
That is, since the change in the current waveform is known based on the drive command signal, if the signal edge of the position detection signal occurs in the region where the change in the current waveform is large, the correction gain is reduced to occur in the region where the change in the current waveform is small. If so, the correction gain is set to a large value. As a result, the correction gain becomes small even if the change in the current waveform is large, so that the angle change becomes small and a large change in the current due to the deviation correction can be prevented. Moreover, when the change in the current waveform is small, the angle change becomes large when the correction gain is increased, but the current does not change significantly. Therefore, the deviation can be corrected efficiently, the deviation between the actual rotation angle and the estimated angle can be eliminated, and the motor can be stably driven.

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. The deviation correction method may be applied not only to the trapezoidal current waveform control but also to the sinusoidal current waveform control as the motor control method. In this case, when the angle differential value is small, that is, in the vicinity of the angles π / 2 and 3π / 2, the region where the current waveform changes is gradual, and in the vicinity of the angles 0 and π, the region where the current waveform changes greatly.

[0037]

As is apparent from the above description, according to the present invention, the estimated angle error can be minimized by performing the stepwise shift correction according to the shift angle when the motor is accelerated or decelerated. , The accuracy of the estimated angle can be improved. Therefore, since the drive control of the motor is performed by the drive command signal based on such an accurate estimated angle, it is possible to suppress the abrupt change of the current and voltage supplied to the stator windings, and the vibration and noise of the motor are generated. Can be prevented.

Therefore, by applying the above-described deviation correction method to a motor that requires a rapid start-up operation such as a dehydration operation of a washing machine, it is possible to suppress torque pulsation and to reduce the vibration and noise of electrical equipment. Can be realized.

[Brief description of drawings]

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

FIG. 2 is a diagram illustrating a deviation correction method.

FIG. 3 is a diagram showing a timing at which a shift correction timing is switched according to a rotation speed.

FIG. 4 is a diagram showing a relationship between a current command value of each phase of a motor and a deviation correction timing.

FIG. 5 is a diagram showing a change in a current command value in a deviation correction section.

FIG. 6 is a diagram illustrating a conventional deviation correction method.

[Explanation of symbols]

1 Position detector 2 Deviation angle / speed measuring instrument 3 angle counter 4 drive circuit

Claims (11)

(57) [Claims] 1. A position detecting means for detecting a rotational position of a rotor, and a counting means for measuring a time interval of a detection signal output from the position detecting means based on a clock signal.
An update amount calculation unit that calculates an angle update amount based on the count number obtained by the counting unit from the rotation angle between the detection signals, and the angle update amount to an estimated angle that is an estimated value of the rotation angle of the rotor. A motor control device comprising: an estimated angle creating means for creating a current estimated angle; and a drive command means for creating a drive command signal to the stator windings corresponding to the current estimated angle. Deviation calculating means for calculating the deviation angle between the actual rotation angle obtained by the detection signal of the position detecting means and the estimated angle at the time of outputting the detection signal, and the deviation.
The deviation correction amount is calculated from the angle and the correction gain to
The misalignment correction amount is set to the angle for the number of times determined according to the gain.
Degree is added to the update amount, and the current estimated angle is
A motor control device comprising: a correction unit that corrects. 2. A position detector for detecting the rotational position of a rotor.
And the time between the detection signals output from the position detecting means.
Counting means for measuring the distance based on the clock signal,
From the rotation angle between the detection signals, the counting means
Calculate the angle update amount based on the count obtained by
With the update amount calculation means to be output and the estimated value of the rotation angle of the rotor
Adding the angle update amount to a certain estimated angle
Estimated angle creation means to create a constant angle and the current estimated angle
Drive command signal to the stator winding
A motor control device having a motion command means, comprising:
During the acceleration / deceleration operation of the
Of the actual rotation angle obtained by
Deviation calculation means to calculate the deviation angle and the current
Corrects the deviation for the deviation angle relative to the constant angle according to the correction gain.
Correction means and the rotation speed of the motor
As the time interval between the detected signals decreases with increasing
, The angular interval of the timing to correct the deviation becomes large.
The correction time switching means for switching
A motor control device characterized by: 3. The number of deviation corrections is the reciprocal of the correction gain.
By the motor control device according to claim 1 or 2, wherein the the. 4. The correction gain increases as the motor acceleration increases.
3. The motor control device according to claim 1 , further comprising a gain adjusting means for setting the gain to a small value . 5. The correction time switching means is a timing for deviation correction.
3. The motor control device according to claim 2, wherein the rotation speed for switching the switching is set to be different from the rotation speed corresponding to the mechanical resonance frequency of the motor. 6. The correction timing switching means corrects the deviation during deceleration.
When switching the timing of, when switching during acceleration
The rotation speed when switching during deceleration
Switch the timing of deviation correction so that
3. The motor control device according to claim 2, wherein a rotation speed for setting is set. 7. The motor control device according to claim 1, wherein the correction means performs the deviation correction within a section where the change of the drive command signal waveform is gradual. 8. The change of the drive command signal waveform becomes gentle.
8. The motor control device according to claim 7, wherein position detection means is installed so as to generate a position detection signal in the section. 9. The generation timing of the position detection signal is the driving
Position detection occurs at the point where the change in the command signal waveform becomes maximum.
A certain amount of advance from the rotation angle when the signal was generated
8. The motor control device according to claim 7 , wherein deviation correction is executed at an angular position . 10. A position detecting signal is generated by the correcting means.
Immediately after that, the correction is performed and the drive command means is set in advance.
The drive command signal waveform is output according to the estimated angle information, and the drive is performed.
The command signal waveform has a relatively high rate of change
The waveform consists of a flat area,
The stage is output at the time when the position detection signal is generated.
Determine which of the above areas the drive command signal belongs to
However, if the area is steep, the correction gain is multiplied by the amount of deviation.
If the area is small and the area is relatively flat, the correction
3. The motor control device according to claim 1 , wherein the correction is performed with the number of inputs set to a large value . 11. A washing machine comprising the motor control device according to any one of claims 1 to 10 and performing a rotation start-up control or a rotation stop control of a dehydration operation.