JP2002051585A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the large change of a drive current at correction of slippage, by lessening the error in an estimated angle at acceleration and deceleration. SOLUTION: This motor controller counts the number of pulses between the signal edges of the detection signal from a position detector which detects the rotational angle of a rotor, and computes the quantity of update of the angle with every pulse. This computes the slippage angle between the estimated angle and the rotational angle, and gets the quantity of slippage correction per pulse from correction gain, and adds this to the quantity of angle update so as to make the present estimated angle. This performs the angle update where the quantity of slippage correction is added by the number of times based on the amount of slip angle, and after that, this performs the angle update by the quantity of angle update. The slip correction by the amount of slip angle is performed in stages at acceleration and deceleration, and the error in estimated angle becomes minimum.

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) for estimating a rotation angle of a rotor from a low-resolution rotation position signal and supplying a current or a voltage changing 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, a brush or the like, 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 a device called a 120-degree energized rectangular wave drive system driven based on a low-resolution rotational position signal. In this motor control system, the power supply to the stator winding is performed by a rectangular wave voltage, so that the current flowing through the stator winding is greatly distorted, and the current change at the time of ON / OFF is large, and the generated torque pulsates. Large, causing vibration and noise of the motor.

In order to solve this problem, for example, a control method for estimating a rotation angle of a rotor in a brushless motor and supplying a voltage that changes in a substantially sinusoidal waveform, an SR method, or the like.
There is a control method for estimating a rotation angle of a rotor in a motor and supplying a current that changes in a trapezoidal waveform.

The above-described rotor angle estimation method is disclosed in, for example, Japanese Patent Application Laid-Open No. H11-215881. The time interval of the signal edge of the position detection signal that has detected the rotational position of the rotor is measured by a pulse counter or the like of the CPU, 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, the acceleration and deceleration of the motor causes a deviation between the absolute angle obtained from the position detection signal and the estimated angle. Therefore, the angle update amount calculated as described above is corrected by an appropriate correction gain to prevent accumulation of the shift amount.

That is, as shown in FIG.
Between degrees and 60 degrees, the number of measurement pulses between signal edges is 6 pulses, and the angle update amount after that is 10 degrees per pulse. Therefore, the current estimated angle is created by adding 10 degrees per pulse to the estimated angle of 60 degrees. Then, at the next signal edge, the absolute angle is 1
Although the angle 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, a shift of 20 degrees must be corrected.

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

[0007]

In the angle estimating method disclosed in the above publication, a 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 the overshoot of the deviation correction, which causes a motor torque ripple or a sharp change in the angle. Greatly changes, causing vibration and noise of the motor.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a motor control device capable of reducing an estimated angle error and suppressing a sudden change in a voltage or a current supplied during deviation correction.

[0009]

According to the present invention, there is provided 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; Updating amount calculating means for calculating an angle updating amount based on a count number obtained by the counting means from a rotation angle between signals; and adding the angle updating amount to an estimated angle which is an estimated value of the rotation angle of the rotor. Estimated angle creating means for creating the current estimated angle, and 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 output of the detection signal during acceleration / deceleration operation of the motor. Deviation calculating means;
And a correcting means for performing a stepwise correction of the shift angle relative to the current estimated angle.

By using the pulse signal of a fixed period 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. As a result, it is possible to create the estimated angle in small steps. Then, a deviation angle is obtained from the actual rotation angle detected by the position detection means and the estimated angle at the time of detection, and a deviation correction amount is calculated by multiplying the deviation angle by a correction gain. The current estimated angle is corrected by adding 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 estimated angle having a small error created in this way, and a current or a voltage is supplied to the stator winding.
Therefore, by performing a fine correction, a sudden change in the estimated angle can be eliminated, and a sudden change in the voltage or current supplied for driving the motor can be suppressed. In particular, this is a preferable correction method for correcting deviation during acceleration / deceleration of the motor.

In order to generate an 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, at the time of acceleration / deceleration, the deviation angle also changes with the change in the rotation speed of the rotor. However, if the correction gain is set to be small when the acceleration is large, and if the correction gain is set to be small when the acceleration is small, the angle change does not become large. In addition, fine correction can be performed in accordance with the change in the rotation angle, and the estimated angle error can be further reduced.

Since the rotation speed of the motor changes during acceleration / deceleration, it is preferable to provide a correction timing switching means for switching the timing for correcting the deviation in accordance with the rotation speed of the motor. When the time interval between the detection signals decreases as the rotation speed increases, switching is performed so that the angle interval of the timing for performing the shift correction is increased, so that the shift correction control is performed at a substantially constant interval regardless of the rotation speed. And the burden on the control device can be reduced.

The rotational speed at which the timing is switched is set to be different from the rotational speed corresponding to the mechanical resonance frequency of the motor. Also, 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.

In order to perform drive control so as to avoid a sudden change in the current or voltage supplied to the stator winding, a shift correction section is set in accordance with the timing at which the drive command signal waveform gradually changes. I do. Here, with regard to the setting of the shift correction section, the position detecting means is provided so that the detection signal is output in accordance with the rotation angle at which the drive command signal waveform gradually changes. Alternatively, the shift correction timing is delayed by a timer or the like so that the shift correction is performed when a predetermined rotation angle is advanced from the time when the detection signal is generated. As a result, the shift correction is performed when the change in the waveform of the current or the voltage is small, so that the change in the current or the voltage can be prevented from increasing even if the estimated angle changes greatly with the shift correction.

Alternatively, gain varying means for varying the correction gain in accordance with the degree of change of the drive command signal waveform may be provided. In other words, if the position detection signal is generated in a region where the signal waveform changes largely, the correction gain is reduced. If the position detection signal is generated in a region where the signal waveform changes little, the correction gain is set to a large value. Can be prevented from changing greatly.

Therefore, if the deviation is corrected when the waveform change of the current or voltage supplied to the stator winding is small,
Even if the correction gain is increased, the effect can be kept to a minimum, and the overshoot of the correction angle is eliminated, and the occurrence of torque ripple, motor vibration, 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 a deviation angle between the position detector 1 including a Hall element or the like for detecting the rotational position of the rotor and an estimated angle from a rotation angle based on a position detection signal from the position detector 1, and calculates a deviation correction amount. And an angle counter 3 for calculating an actual angle of rotation and a rotational acceleration from the rotational angle, and an angle counter 3 for producing an estimated angle corrected by a deviation corresponding to the angle of deviation. And a CPU (not shown) for controlling the driving of the drive circuit 4 to generate a drive command signal for the stator windings in accordance with the estimated angle, and for correcting the deviation and controlling the motor drive.

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

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 Output. The drive circuit 4 includes a PWM signal generator, an inverter circuit, and the like. The drive circuit 4 generates a three-phase sine-wave drive command signal or a trapezoidal drive command signal from the estimated angle, and generates a three-phase drive command signal proportional to the drive command signal by PWM control. A sine wave excitation current or a trapezoidal excitation current is output, and the excitation current is supplied to the stator winding. Also, the number of times of adding the shift correction amount is determined by the correction gain, and the number of times is set to the reciprocal of the correction gain, and the total shift shift amount is the shift angle. In the figure, Δθ is a shift correction amount, θupdate is an angle update amount,
θc is an estimated angle, and K is a correction gain.

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

At this time, the rotation angle between the signal edges is 60
The degree and count are 4 pulses, so the angle update amount is 1
5 degrees. Assuming that the correction gain is 0.5, the shift correction amount per pulse is 20 degrees * (correction gain) = 20 degrees × 0.5 = 10 degrees. Further, since the shift correction amount per pulse is 10 degrees, the shift angle corresponds to two pulses, and the shift correction for the shift angle can be performed by two angle updates.

Then, the first angle update is performed by adding 25 degrees, which is the sum of the deviation correction amount and the angle update amount, to the estimated angle. As the second angle update according to the next pulse,
This is performed by adding the deviation correction amount to the angle update amount to the updated estimated angle in the same manner as described above. With these two angle updates,
The shift correction amount reaches the shift angle, and the shift correction is completed. In the third and subsequent angle updates, it is not necessary to consider the shift correction amount, and only the angle update amount of 15 degrees is added to the estimated angle. It should be noted that deviation correction is similarly performed during deceleration.

Therefore, the estimated angle error can be minimized by performing the correction for the deviation angle stepwise during acceleration / deceleration. Moreover, since the estimated angle does not suddenly change at the time of deviation correction, it is possible to suppress a sudden 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, overshoot of deviation correction can be prevented, and occurrence of torque ripple of the motor can be prevented.

Incidentally, during acceleration / deceleration, the rotational speed (rotational speed) of the rotor changes, so that the deviation angle also changes. Therefore, since the acceleration of the rotor can be detected by measuring the time interval between signal edges, a gain adjustment function for setting a correction gain in accordance with the acceleration may be added to the CPU. For example, when the acceleration is large, the correction gain is set small, and when the acceleration is small, the correction gain is set small. As a result, fine correction can be performed in accordance with the change in the rotation angle, the estimation angle error can be further reduced, and the rotation angle can be accurately estimated.

When the rotation speed (the number of rotations) is high, the time interval between signal edges becomes small, and C
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 operation and accelerating, deviation correction is performed every 60 degrees up to 100 rpm, and every 360 degrees up to 100 rpm and up to 1000 rpm.
10000r every 6 rotations (2160 degrees) up to pm
When the rotation speed exceeds pm, the displacement is corrected every 36 rotations (12,960 degrees).

As described above, since the time interval between signal edges becomes smaller as the rotation speed increases, the rotation speed of the rotor becomes higher in the CPU by switching so as to increase the angle interval of the timing for performing the deviation correction. Can also execute the deviation correction control at substantially constant intervals.
The burden on the PU can be reduced.

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

The switching timing may be changed during deceleration in the same manner. However, since the change in rotation speed is different between acceleration and deceleration, hysteresis is provided for the rotation speed for switching the timing of deviation correction. deep. That is, if the rotation speed is set higher than during deceleration during acceleration, such as switching at 100 rpm during acceleration, for example, at 80 rpm during deceleration, the occurrence of a single vibration in the rotation speed of the motor during switching is prevented. It is possible to achieve stability at the time of switching.

The above-described motor control device is suitable for controlling the motor of a washing machine. In particular, when the motor control device is applied to the correction of the rotation angle deviation at the start of rotation and at the start of rotation of the spin-drying operation, the torque is reduced. Pulsation can be suppressed. Further, it is possible to avoid unstable behavior at the time of switching the angle interval for performing the deviation correction, and it is possible to suppress generation of vibration and noise.

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

FIG. 4 shows the current command values of the respective phases A, B, and C of the motor during steady operation without an 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 at the time of acceleration, deviation correction is performed after a signal edge appears.
As shown in (2), if there is a signal edge output when the energized phase is switched, the change of the current waveform becomes drastic in this shift correction section. In particular, when the correction gain is large, the change in the current waveform becomes sharper, which causes the motor to vibrate.

Therefore, when the current waveform gradually changes, that is, in the top flat region of the current waveform,
What is necessary is just to attach the position detector 1 so that a position detection signal may be generated. That is, if the phase of the command current is constant,
Since it is known in advance which rotation angle will be the top flat area, the mounting position of the position detector 1 can be adjusted at the design stage so that the rotation angle corresponding to the top flat area can be detected. Therefore, when a signal edge is generated from the position detection signal, the change in the current waveform is small. If the shift 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 angle of occurrence of the signal edge of the position detector 1 at the design stage,
The above installation is not possible. When the phase of the current waveform changes, the area where the current waveform does not change also changes, but it is impossible to change the mounting position of the position detector 1 during operation of the motor. . In such a case, the shift correction is not performed immediately after the occurrence of the signal edge, but is delayed by a timer or the like so that the shift correction section covers the top flat area. That is, after the signal edge occurs, the angle is updated as necessary,
When the estimated angle has reached the position corresponding to the top flat area, deviation correction is performed. This makes it possible to always perform the shift correction in accordance with the timing at which the change in the current waveform becomes gentle, and it is possible to prevent the change in current accompanying the shift correction from increasing.

As another method, the correction gain may be varied according to the degree of change in the current waveform.
That is, since the change in the current waveform can be known based on the drive command signal, if the signal edge of the position detection signal occurs in a region where the change in the current waveform is large, the correction gain is reduced and the signal edge is generated in a region where the change in the current waveform is small. Then, the correction gain is set large. As a result, even if the change in the current waveform is large, the correction gain is small, so that the angle change is small, and a large change in the current accompanying the deviation correction can be prevented. In addition, when the change in the current waveform is small, the angle change increases 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 driven stably.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention. As a motor control method, the above-described deviation correction method may be applied to not only a trapezoidal current waveform control but also a sinusoidal current waveform control. In this case, when the angle differential value is small, that is, near the angles π / 2 and 3π / 2, the current waveform changes gradually, and near the angles 0 and π, the current waveform changes largely.

[0037]

As is apparent from the above description, according to the present invention, the estimated angle error can be minimized by performing the shift correction stepwise according to the shift angle during the acceleration and deceleration of the motor. , The accuracy of the estimated angle can be increased. Therefore, since the drive of the motor is controlled by the drive command signal based on the accurate estimated angle, it is possible to suppress a sudden change in the current or voltage supplied to the stator winding, and to generate the motor vibration and noise. Can be prevented.

Therefore, by applying the above-described shift correction method to a motor that requires a rapid start-up operation such as a spin-drying operation of a washing machine, torque pulsation can be suppressed and electric equipment with less vibration and noise can be used. Can be realized.

[Brief description of the 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 for explaining a displacement correction method.

FIG. 3 is a diagram showing a timing of switching a shift correction timing 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 timing of deviation correction.

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

FIG. 6 is a view for explaining a conventional shift correction method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Position detector 2 Deviation angle / speed measuring device 3 Angle counter 4 Drive circuit

Continued on the front page F-term (reference) 3B155 AA06 BA04 KA36 KB11 LA01 LB18 LB27 MA05 MA06 MA08 5H550 AA20 BB05 DD08 DD09 GG10 HB07 HB16 JJ03 JJ04 LL10 LL35 MM19 5H560 AA10 BB04 BB12 DA02 X15 EB01 GG01

Claims (11)

[Claims] 1. A position detecting means for detecting a rotational position of a rotor, a counting means for measuring a time interval between detection signals output from the position detecting means based on a clock signal,
Update amount calculating means for calculating an angle update amount based on the count number obtained by the counting means from the rotation angle between the detection signals; and adding the angle update amount to an estimated angle which 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 instruction means for creating a drive instruction signal to the stator winding corresponding to the current estimated angle, comprising: During acceleration / deceleration operation, a deviation calculating unit that calculates a deviation angle between an actual rotation angle obtained by a detection signal of the position detection unit and an estimated angle at the time of output of the detection signal, and a deviation from a current estimated angle. A motor control device, comprising: a correction unit that performs a stepwise correction of an angle shift. 2. The method according to claim 1, wherein the correcting means calculates a shift correction amount from the shift angle and the correction gain, and adds the shift correction amount to the angle update amount a number of times determined according to the correction gain. The motor control device according to any one of the preceding claims. 3. The motor control device according to claim 1, further comprising gain adjustment means for setting a correction gain according to the acceleration so that the correction gain decreases as the acceleration of the motor increases. . 4. The motor control device according to claim 1, further comprising a correction timing switching unit that switches a timing of performing the deviation correction according to a rotation speed of the motor. 5. The correction timing switching means sets a rotation speed at the time of switching to be different from a rotation speed corresponding to a mechanical resonance frequency of the motor.
The motor control device according to any one of the preceding claims. 6. The motor control device according to claim 4, wherein the correction timing switching means sets the rotation speed when switching during acceleration and the rotation speed when switching during deceleration differently. 7. The motor control device according to claim 1, wherein the correction means sets the shift correction section in accordance with a timing at which the drive command signal waveform gradually changes. 8. The motor control device according to claim 7, wherein the position detection means is provided so that the detection signal is output in accordance with the rotation angle at which the drive command signal waveform gradually changes. 9. The motor control device according to claim 7, wherein the deviation correction section is set when a predetermined rotation angle is advanced from a point in time when the detection signal is generated. 10. The motor control device according to claim 1, further comprising a gain varying unit that varies a correction gain in accordance with a degree of change of the drive command signal waveform. 11. A washing machine comprising the motor control device according to any one of claims 1 to 10, wherein the washing machine performs rotation start-up control or spin-down control of a spin-drying operation.