JP2011083191A - Motor control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate detecting and correcting position signals with high accuracy, even when shift of phase difference occurs in a plurality of the detected position signals, in a motor control device having a position detector. <P>SOLUTION: The motor control device includes a speed controller 106 for controlling a motor 100 at a constance speed and an phase shift corrector 504 for detecting and correcting the shift of phase difference of a plurality of position signals of a position detector 102 by analyzing the speed error with a frequency analyzer 500. Even when the shift of phase difference occurs in the position signals of the position detector, the shift can be corrected easily and accurately, by including the phase shift corrector. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a motor control device having a position detector that outputs sine-wave position signals having different phases to detect the position of the motor, even when the position signal offset or phase difference deviates from a desired value. The present invention relates to a motor control apparatus that controls, for example, a motor for driving a photoconductor of an electrophotographic process, which can always perform accurate control, particularly speed control, by easily detecting and correcting.

  In order to control the motor with high accuracy, the accuracy of the position detector that detects the position of the motor is indispensable, and correction devices that correct the offset of the position signal output from the position detector have been widely used.

  The operation of an example of correcting the offset of the position signal output by the conventional position detector will be described.

  A position detector for detecting the position of the motor is attached to the motor, and the position signal of the position detector is, for example, two general A phase and B phase signals that are two sinusoidal signals that are 90 degrees out of phase with each other. Phase signals MR1 and MR2 are output, and their respective outputs Pa and Pb are

Suppose that Here, θs is the phase of the position detector, Aa and Ab are the amplitudes of the respective signals, and Pao and Pbo are the offset values of the respective signals. In this case, as in Patent Document 1, for example, an offset detection operation for rotating the position signal of the position detector by one cycle or more is required, and the maximum value and the minimum value of the output values of the A phase and the B phase are detected. And

As described above, the offset value of each phase can be detected from these average values. Here, Max (x) represents the maximum value of x, and Min (x) represents the minimum value of x.

  As a result, even when the position signal of the position detector has an offset, the offset can be detected and the offset can be corrected.

  further,

JP-A-8-35857

  However, in the conventional method of detecting the offset by detecting the maximum value and the minimum value of the position signal, an offset detection operation is required, and when the position signal is detected at a predetermined period predetermined by a microprocessor or the like. However, since the maximum value and the minimum value cannot be detected unless the motor rotation speed at the time of the offset detection operation is sufficiently slow, the offset detection operation requires a long time. Similarly, there is a problem in that it takes a long time to detect the amount of phase difference deviation when there is a phase difference deviation among the plurality of position signals of the position detector.

  In order to solve the above problems, the motor control device of the present invention outputs a position signal having a constant multiple of one rotation of the motor and a plurality of sinusoidal waveforms having different phases according to the position of the motor. In a motor control device having a position detector that performs, a speed detection means that outputs a rotation speed of the motor from an output of the position detector, and a predetermined rotation speed of the motor according to the output of the speed detection means Speed control means for controlling the speed command value of the motor, frequency analysis means for frequency analysis of a deviation between the output of the speed detection means and the speed command value, and the rotational speed of the motor by the speed control means A phase that outputs a phase difference discriminating value for judging the magnitude of the phase difference of the plurality of position signals of the position detector from the output of the frequency analysis means after being controlled in the vicinity of the command value A determination unit, but having a phase difference correcting means for correcting the shift amount of the phase difference of the position detector from the phase difference determination value.

  As is clear from the description of the above embodiment, the motor control device of the present invention has a motor and a plurality of sinusoidal waveforms having phases different from each other depending on the position of the motor, and the motor rotates once and has a constant multiple cycle. In a motor control device having a position detector that outputs a position signal, speed detection means for outputting the rotation speed of the motor from the output of the position detector, and the rotation speed of the motor according to the output of the speed detection means Speed control means for controlling to a predetermined constant speed command value, frequency analysis means for frequency analysis of a deviation between the output of the speed detection means and the speed command value, and rotation of the motor by the speed control means. After the speed is controlled in the vicinity of the speed command value, the phase difference discriminating value for judging the magnitude of the phase difference of the plurality of position signals of the position detector from the output of the frequency analyzing means. By providing phase difference determining means for outputting and phase difference correcting means for correcting the phase difference of the position detector from the phase difference determined value, a plurality of position signals of the position detector are shifted in phase difference. Even if there is, there is a possibility that correction can be easily performed with high accuracy, and control with high accuracy is possible.

1 is an overall view showing a configuration of a motor control device according to a first embodiment of the present invention. Conceptual diagram of position detector Explanatory drawing which shows an example of the position signal which is an output of a position detector Explanatory diagram showing an example of the output of the frequency analyzer Explanatory drawing showing another example of the output of the frequency analyzer Conceptual diagram showing the operation of the offset amount discriminator Overall view showing a configuration of a motor control device according to a second embodiment of the present invention. Explanatory drawing showing the characteristics of the filter Overall view showing a configuration of a motor control device according to a third embodiment of the present invention. Overall view showing a configuration of a motor control device according to a fourth embodiment of the present invention. Overall view showing a configuration of a motor control device according to a fifth embodiment of the present invention. Explanatory drawing which shows an example of the position signal which is an output of a position detector Explanatory diagram showing an example of the output of the frequency analyzer Overall view showing a configuration of a motor control device according to a sixth embodiment of the present invention.

  The present invention relates to a motor control apparatus including a motor and a position detector that outputs a position signal having a plurality of sinusoidal phases different from each other in phase according to the position of the motor, and the motor outputs a constant signal with a period of one rotation. Speed detecting means for outputting the rotational speed of the motor from the output of the position detector, and speed control means for controlling the rotational speed of the motor to a predetermined constant speed command value according to the output of the speed detecting means. Frequency analysis means for analyzing the frequency difference between the output of the speed detection means and the speed command value; and the frequency analysis after the rotational speed of the motor is controlled in the vicinity of the speed command value by the speed control means. A phase difference discriminating means for outputting a phase difference discriminating value for judging the magnitude of the phase difference of the plurality of position signals of the position detector from the output of the means, and a position detection from the phase difference discriminating value Those having a phase difference correcting means for correcting the phase difference.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is an overall view showing the configuration of the motor control device according to the first embodiment of the present invention.

  In FIG. 1, 100 is a motor, 102 is a position detector, 104 is a current controller, 106 is a speed controller, 108 is a differentiator, 110 is a position signal processor, 112 is a subtractor, 114 is a frequency analyzer, 116 Is an offset amount discriminator, and 118 is an offset corrector.

  FIG. 2 is a conceptual diagram of the position detector.

  FIG. 3 is an explanatory diagram showing an example of a position signal which is an output of the position detector.

  FIG. 4 is an explanatory diagram showing an example of the output of the frequency analyzer.

  FIG. 5 is an explanatory diagram showing another example of the output of the frequency analyzer.

  FIG. 6 is a conceptual diagram showing the operation of the offset amount discriminator.

  The operation of the motor control apparatus configured as described above will be described below with reference to FIGS. 1, 2, 3, 4, 5, and 6. FIG.

Similar to a conventional motor control device, a position detector 102 for detecting the position of the motor is attached to the motor 100. As shown in FIG. 2, the position detector 102 detects a magnetized pattern of a magnet magnetized in advance with an MR element, and outputs signals MR1 and MR2 having a phase of 90 degrees. These MR1 and MR2 signals are corrected for their respective offsets by the offset corrector 118 and then input to the position signal processor 110 to detect the position of the motor. The operation of the position signal processor 110 may be obtained by an inverse trigonometric function from, for example, MR1 and MR2 signals. Further, this position signal is converted into a motor speed by the differentiator 108. The speed controller 106 may be controlled by, for example, known PI control so that the detected speed follows the speed command value, and outputs a torque command for that purpose to the current controller 104. The current controller 104 controls the current supplied to the motor 100 so as to generate the commanded torque by, for example, known PI control.

  Next, the offset correction operation of the present invention will be described in detail.

  Assume that the position signals MR1 and MR2 from the position detector 102 have an offset as shown in FIG. Here, θm is the position of the motor, and MR1 and MR2 are assumed to have a cycle twice as long as one rotation of the motor. Therefore, the position signal outputs a signal for two cycles at a rotation angle of 360 degrees per motor rotation. When the position signal has an offset as shown in FIG. 3, the position of the motor obtained by processing by the position signal processor 110 has an error that changes every cycle of the position signal due to the influence of the offset. For this reason, an error that changes every cycle of the position signal also occurs in the detection speed of the motor calculated by the differentiator 108. Therefore, when speed control is performed with a predetermined constant speed command, the speed error ωe between the speed command value ωd calculated by the subtractor 112 and the motor detection speed ωm is:

Thus, when this speed error ωe is subjected to a known frequency analysis by the frequency analyzer 114, a waveform having a peak at a frequency twice the speed command value ωm can be obtained. That is, it can be seen that peaks appear at the frequencies of the position signals MR1 and MR2. The offset value discriminator 116 sets this peak value as an offset discriminating value. FIG. 4 shows an example of actual frequency analysis of the speed error. The peak on the right side of FIG. 4 where the frequency is high is the peak of the frequency component of the position signal, and this peak value is the offset discrimination value. In FIG. 4, in addition to the frequency peak of the position signal, a peak is also observed at a low frequency on the left side, which is a peak of the cogging component of the motor.

  The offset discrimination value, which is the peak value of the frequency component of the position signal, decreases as the offset decreases, as shown in FIG. That is, it can be seen that the offset determination value has a minimum value as shown in FIG. 6 and this case is a case where there is no offset in the position signal. Further, due to the nature of the offset, even if the offset of the position signal other than the position signal to be adjusted is an arbitrary value, the minimum value under that condition can be obtained. Therefore, for example, the offset corrector 118 fixes the offset value set by MR2, and changes the offset set by MR1 to adjust the offset discriminant value to be minimum. After that, if the offset value set by MR1 is fixed and the offset value set by MR2 is changed and adjusted so as to minimize the offset discriminant value, the position signal can be adjusted to have no offset.

  The method of detecting this minimum value is an operation in which the offset value to be set is temporarily shifted in an arbitrary direction due to the nature of the offset shown in FIG. It can be seen that this can be easily realized by repeating the same correction operation until the minimum value is repeated.

With the above configuration, even when the offset of the position signal of the position detector is deviated, it can be easily detected and corrected. In particular, when speed control is performed at a constant speed, it is possible to always detect and correct an offset even during speed control, so even if a position signal offset occurs due to a temperature rise during energization, speed control is performed. The offset can be corrected without interruption, and optimum speed control is always possible.

  Here, for convenience of explanation, the position signals MR1 and MR2 of the position detector are assumed to have a cycle twice as long as one rotation of the motor, but may be a constant and sufficiently higher than the frequency of the cogging component of the motor. The frequency case is common. This constant is a natural number that is an integer of 1 or more when the motor and the position detector are directly connected as in the present embodiment, but a gear or the like is attached to the motor and the gear is decelerated or accelerated. When a position detector is attached to the shaft, the natural number may not be obtained depending on the gear ratio.

  Furthermore, although the speed control has been described here, even in the case of position control or torque control, if there is a period during which control is performed at a constant speed, it is possible to detect and correct the offset during that period. Also, a speed control test operation may be incorporated for offset correction.

  Here, the offset discriminant value is obtained by frequency analysis of the speed error ωe, but the torque command value that is the output of the speed controller 106 may be frequency analyzed, and a similar result is obtained.

  Next, in the first embodiment, the frequency analysis is performed by the frequency analyzer and the offset discriminant value is obtained. However, when the frequency analysis is performed, the calculation amount increases, and the arithmetic unit for controlling the motor becomes expensive. There was a problem.

  Thus, as a second embodiment of the present invention, there is provided a motor control device that can easily obtain an offset determination value and correct an offset of a position signal.

(Embodiment 2)
Hereinafter, a motor control apparatus according to a second embodiment of the present invention will be described with reference to the drawings.

  FIG. 7 is an overall view showing the configuration of the motor control device according to the second embodiment of the present invention.

  In FIG. 7, 100 is a motor, 102 is a position detector, 104 is a current controller, 106 is a speed controller, 108 is a differentiator, 110 is a position signal processor, 112 is a subtractor, 118 is an offset corrector, 200 Is a filter, and 202 is an offset amount discriminator.

  FIG. 8 is an explanatory diagram showing the characteristics of the filter.

  About the motor control apparatus comprised as mentioned above, the operation | movement is demonstrated below using FIG. 7, FIG.

Similar to the motor control apparatus of the first embodiment, a position detector 102 for detecting the position of the motor is attached to the motor 100 and outputs signals MR1 and MR2 having a phase of 90 degrees. These MR1 and MR2 signals are corrected for their respective offsets by an offset corrector 118, and then input to a position signal processor 110 to detect the position of the motor, and further converted to a motor speed by a differentiator 108. . The speed controller 106 outputs a torque command to the current controller 104 so that the detected speed follows the speed command value, and the current controller 104 supplies the commanded torque to the motor 100. Control the current.

  Next, the offset correction operation of the present invention will be described in detail.

  As in the first embodiment, the position signals MR1 and MR2 from the position detector 102 have a cycle twice as long as one rotation of the motor and have an offset as shown in FIG. The position and speed of the motor determined by the differentiator 108 cause an error that changes every period of the position signal. Therefore, when speed control is performed with a predetermined constant speed command, a frequency fluctuation component twice the speed command value ωm, which is the frequency of the position signal, is added to the speed error ωe calculated by the subtractor 112.

  Therefore, for example, as shown in FIG. 8, the filter 200 is a secondary bandpass filter, and a filter that cuts frequency components other than the vicinity of the frequency of the position signal is configured. By passing the speed error ωe through the filter 200, it is possible to mainly extract components near the frequency of the position signal. That is, the component of the speed error generated due to the presence of the offset can be detected by the value passed through the filter 200, and the offset amount discriminator 202 may use this value as the offset discrimination value.

  Similarly to the first embodiment, the offset determination value is also adjusted by the offset corrector 118 so that the offset determination value is minimized because the position signals MR1 and MR2 have minimum values when the set offset value is shifted. In this case, the position signal can be adjusted to have no offset.

  With the above configuration, it is possible to obtain an offset determination value with a simple filter and correct the offset, and it is possible to perform accurate motor control even with an inexpensive arithmetic device.

  Although the filter characteristic is the second-order bandpass filter shown in FIG. 8, any configuration may be used as long as it is a filter that cuts frequency components other than the vicinity of the frequency of the position signal.

  In addition, the value after passing through the filter may include vibration components other than the frequency component of the position signal in the vicinity of the frequency of the position signal, but it does not change even if the offset is changed. It will not be harmful.

  Further, here, the offset discriminant value is obtained by frequency analysis of the speed error ωe, but the torque command value that is the output of the speed controller 106 may be passed through a filter, and the same result is obtained.

  Next, in the first and second embodiments, by correcting the offset so as to minimize the offset determination value, high-precision correction can be performed, but when the offset is greatly shifted, There is a problem that the number of repetitions for obtaining the minimum value increases and the time for offset correction becomes long.

  Therefore, as a third embodiment of the present invention, there is provided a motor control device capable of shortening the offset correction time even when the offset largely deviates.

(Embodiment 3)
A motor control apparatus according to a third embodiment of the present invention will be described below with reference to the drawings.

  FIG. 9 is an overall view showing the configuration of the motor control device according to the third embodiment of the present invention.

In FIG. 9, 100 is a motor, 102 is a position detector, 104 is a current controller, 106 is a speed controller, 108 is a differentiator, 110 is a position signal processor, 112 is a subtractor, 114 is a frequency analyzer, 116 Is an offset amount discriminator, 300 is an offset change width storage means, and 302 is an offset corrector.

  About the motor control apparatus comprised as mentioned above, the operation | movement is demonstrated using FIG. 9 below.

  Similar to the motor control apparatus of the first embodiment, a position detector 102 for detecting the position of the motor is attached to the motor 100 and outputs signals MR1 and MR2 having a phase of 90 degrees. These MR1 and MR2 signals are corrected for their respective offsets by an offset corrector 118, and then input to a position signal processor 110 to detect the position of the motor, and further converted to a motor speed by a differentiator 108. . The speed controller 106 outputs a torque command to the current controller 104 so that the detected speed follows the speed command value, and the current controller 104 supplies the commanded torque to the motor 100. Control the current.

  As in the first embodiment, the position signals MR1 and MR2 from the position detector 102 have a predetermined constant speed assuming that there is an offset as shown in FIG. When speed control is performed using a command, a fluctuation component having a frequency twice as large as the speed command value ωm, which is the frequency of the position signal, is added to the speed error ωe calculated by the subtractor 112. This signal is frequency-analyzed by the frequency analyzer 114 to obtain a waveform having a peak at twice the frequency of the speed command value ωm, and the offset amount discriminator 116 sets this peak value as an offset discriminant value.

  Next, the offset correction operation of the present invention will be described in detail.

  It can be seen that the relationship between the offset of the position signals MR1 and MR2 and the offset discriminant value has a minimum value as shown in FIG. 6, and the change of the offset discriminant value becomes small near the minimum value. The offsets of the position signals MR1 and MR2 change depending on environmental conditions such as temperature, but there is little variation in the relationship between the offset change width and the offset determination value change width. Therefore, the relationship between the offset change width and the offset determination value change width is measured in advance and stored in the offset change width storage means 300. Then, the offset value set by the offset corrector 302 is changed by a predetermined change width, and the change width of the offset discriminant value at that time is set to the offset change width stored in the offset change width storage means 300 and the offset discriminant value. Compared to the relationship with the change width, an approximate offset can be obtained. After that, as in the first embodiment, the offset value to be set is shifted and adjusted so that the offset discriminant value is minimized, so that the number of repetitions for obtaining the minimum value can be increased even when the offset is greatly shifted. And offset correction can be realized at high speed.

  Next, in the third embodiment, it is possible to realize offset correction at high speed by measuring and storing the relationship between the offset change width and the offset discrimination value change width in advance. However, there is a problem that the cost of the storage means for storing the relationship between the offset change width and the offset determination value change width is increased. In addition, it is not only necessary to measure in advance the relationship between the offset change width and the offset discrimination value change width for each type of position detector, but even when the position detector is the same, When the motor speed command value is different, there is a problem in that it is necessary to measure the relationship between the change width of the offset and the change width of the offset determination value again.

  Therefore, as a fourth embodiment of the present invention, the motor control capable of detecting and correcting the offset value of the position detector at high speed without storing the relationship between the offset change width and the offset discriminant value change width. Providing the device.

(Embodiment 4)
A motor control apparatus according to a fourth embodiment of the present invention will be described below with reference to the drawings.

  FIG. 10 is an overall view showing the configuration of the motor control device according to the fourth embodiment of the present invention.

  In FIG. 10, 100 is a motor, 102 is a position detector, 104 is a current controller, 106 is a speed controller, 108 is a differentiator, 110 is a position signal processor, 112 is a subtractor, 114 is a frequency analyzer, 116 Is an offset amount discriminator, 118 is an offset corrector, 400 is an offset coarse adjuster, and 402 is a switch.

  About the motor control apparatus comprised as mentioned above, the operation | movement is demonstrated using FIG. 10 below.

  Similar to the motor control apparatus of the first embodiment, a position detector 102 for detecting the position of the motor is attached to the motor 100 and outputs signals MR1 and MR2 having a phase of 90 degrees. These MR1 and MR2 signals are corrected for their respective offsets by an offset corrector 118, and then input to a position signal processor 110 to detect the position of the motor, and further converted to a motor speed by a differentiator 108. . The speed controller 106 outputs a torque command to the current controller 104 so that the detected speed follows the speed command value, and the current controller 104 supplies the commanded torque to the motor 100. Control the current.

  Next, the offset correction operation of the present invention will be described in detail.

  Assume that the position signals MR1 and MR2 from the position detector 102 have an offset as shown in FIG. 3 at a cycle twice that of one rotation of the motor, as in the first embodiment.

  First, the switch 402 is connected to the offset coarse adjuster 400. The offset coarse adjuster 400 executes an offset detection operation for rotating at least one cycle of the position signal of the position detector in advance as in the conventional motor control device, and at that time, the maximum of each of the position signals MR1 and MR2 is maximum. The value and the minimum value are detected, the respective average values are obtained, and the offset of each position signal is detected. Then, the offset is corrected by subtracting the offset of the position signal from the position signal.

  Next, the switch 402 is connected to the offset corrector 118. The speed of the motor is obtained by using the position signal whose offset is coarsely adjusted by the offset coarse adjuster 400, and the speed is controlled by using this motor speed with a predetermined constant speed command as in the first embodiment. And the frequency analyzer 114 analyzes the frequency of the speed error ωe calculated by the subtractor 112 at that time. Then, a waveform having a peak at twice the frequency of the speed command value ωm can be obtained, and the offset value discriminator 116 sets this peak value as an offset discriminant value. Then, it is possible to correct the offset with high accuracy by adjusting the offset discriminating value to be the minimum by shifting the set offset value.

  As is clear from the configuration of the present embodiment, the accuracy of the offset obtained by the offset coarse adjuster 400 may be poor. Therefore, the accuracy of the maximum value and the minimum value of the position signal needs to be high. Absent. Therefore, it is possible to perform the operation at the time of the offset detection operation, which has conventionally been a problem of measurement time, at high speed.

As a result, the amount of offset corrected by the offset corrector 118 is reduced, so that it is not necessary to measure and store the relationship between the offset change width and the offset discrimination value beforehand, and the motor speed command value can be arbitrarily set. Even with this value, offset correction can be realized at high speed.

Next, in the first, second, third, and fourth embodiments, it has been described that the offsets of the plurality of position signals of the position detector can be easily corrected. There is a problem in that the detection accuracy of the position detector deteriorates due to the phase difference of.

  Therefore, as a fifth embodiment of the present invention, there is provided a motor control device capable of easily detecting a phase difference shift when a phase difference between a plurality of position signals of a position detector is shifted.

(Embodiment 5)
A motor control apparatus according to a fifth embodiment of the present invention will be described below with reference to the drawings.

  FIG. 11 is an overall view showing the configuration of the motor control device according to the fifth embodiment of the present invention.

  In FIG. 11, 100 is a motor, 102 is a position detector, 104 is a current controller, 106 is a speed controller, 108 is a differentiator, 110 is a position signal processor, 112 is a subtractor, 500 is a frequency analyzer, 502 Is a phase shift amount discriminator, and 504 is a phase shift amount corrector.

  FIG. 12 is an explanatory diagram showing an example of a position signal which is an output of the position detector.

  FIG. 13 is an explanatory diagram showing an example of the output of the frequency analyzer.

  The operation of the motor control apparatus configured as described above will be described below with reference to FIGS. 11, 12, and 13.

  Similar to the motor control apparatus of the first embodiment, a position detector 102 for detecting the position of the motor is attached to the motor 100, and the position signals MR1 and MR2 having a phase of 90 degrees are output from each other. These MR1 and MR2 signals are corrected by the phase shift amount corrector 504 for the phase shift amount of the position signal, and then input to the position signal processor 110 to detect the position of the motor. Further, it is converted into a motor speed by the differentiator 108. The speed controller 106 outputs a torque command to the current controller 104 so that the detected speed follows the speed command value, and the current controller 104 supplies the commanded torque to the motor 100. Control the current.

  Next, the operation of detecting the amount of phase difference shift according to the present invention will be described in detail.

As shown in FIG. 12, the position signals MR1 and MR2 from the position detector 102 deviate from the normal broken line waveform to the solid line waveform, and the position signals MR1 and MR2 have a phase difference. . Here, θm is the position of the motor, and MR1 and MR2 are assumed to have a cycle twice as long as one rotation of the motor. Therefore, the position signal outputs a signal for two cycles at a rotation angle of 360 degrees per motor rotation. When there is a deviation in the phase difference of the position signal as shown in FIG. 12, the position of the motor obtained by processing by the position signal processor 110 is every two cycles of one cycle of the position signal due to the influence of the deviation of the phase difference. An error that changes is generated. For this reason, an error that changes every twice the cycle of the position signal also occurs in the detection speed of the motor calculated by the differentiator 108. Therefore, when speed control is performed with a predetermined constant speed command, a frequency error ωe between the speed command value ωd calculated by the subtractor 112 and the motor detection speed ωm is analyzed by a frequency analyzer 500 using a known frequency analysis. A waveform having a peak at a frequency four times the speed command value ωm can be obtained. That is, it can be seen that a peak appears at a frequency twice the frequency of the position signals MR1 and MR2. The peak value is set as a phase difference discrimination value by the phase shift discriminator 502. An example of a frequency analysis of the speed error is shown in FIG. The peak on the right side of FIG. 13 where the frequency is high is the peak of the frequency component twice the frequency of the position signal, and this peak value is the phase difference determination value. In FIG. 13, the frequency of the position signal and the peak of the cogging component of the motor are observed in addition to the peak of the frequency twice the position signal, as in the first embodiment.

The phase difference discrimination value, which is the peak value of the frequency component twice the frequency of this position signal, is
The smaller the phase difference deviation amount, the smaller. That is, it can be seen that the phase difference discriminating value has a minimum value, and this case is a case where there is no shift in the phase difference of the position signal.

  Therefore, the phase shift amount corrector 504 stores, for example, a plurality of position signals whose phases are shifted in advance, and shifts at least one position signal of the position signals MR1 and MR2 input by the position detector in advance. If the position signal is converted into the position signal and adjusted so that the phase difference discriminating value is minimized, the position signal can be adjusted to have no phase difference deviation.

  With the above configuration, even when the phase difference of the position signal of the position detector is shifted, it can be easily detected and corrected. In particular, when speed control is performed at a constant speed, it is possible to detect and correct a phase difference constantly even during speed control. Therefore, a phase signal phase difference has occurred due to a temperature rise during energization. Even in this case, it is possible to correct the phase difference deviation without interrupting the speed control, and the optimum speed control can always be performed.

  Here, for convenience of explanation, the position signals MR1 and MR2 of the position detector are assumed to have a cycle twice as long as one rotation of the motor, but may be a constant and sufficiently higher than the frequency of the cogging component of the motor. The frequency case is common. This constant is a natural number that is an integer of 1 or more when the motor and the position detector are directly connected as in the present embodiment, but a gear or the like is attached to the motor and the gear is decelerated or accelerated. When a position detector is attached to the shaft, the natural number may not be obtained depending on the gear ratio.

  Furthermore, although the speed control has been described here, even in the case of position control or torque control, if there is a period during which control is performed at a constant speed, it is possible to detect and correct a phase difference deviation during that period. Also, a speed control test operation may be incorporated for correcting the phase difference.

  Here, the phase difference determination value is obtained by frequency analysis of the speed error ωe, but the torque command value that is the output of the speed controller 106 may be frequency analyzed, and the same result is obtained.

  Next, in the fifth embodiment, the frequency analysis is performed by the frequency analyzer and the phase difference discriminant value is obtained. However, when the frequency analysis is performed, the calculation amount increases and the arithmetic unit for controlling the motor becomes expensive. There was a problem.

  Thus, as a sixth embodiment of the present invention, there is provided a motor control device capable of easily obtaining a phase difference determination value and correcting a shift amount of a phase difference between a plurality of position signals.

(Embodiment 6)
A motor control apparatus according to a sixth embodiment of the present invention will be described below with reference to the drawings.

FIG. 14 is an overall view showing the configuration of the motor control device according to the sixth embodiment of the present invention.

  In FIG. 14, 100 is a motor, 102 is a position detector, 104 is a current controller, 106 is a speed controller, 108 is a differentiator, 110 is a position signal processor, 112 is a subtractor, and 504 is a phase shift amount corrector. , 600 are filters, and 602 is a phase shift amount discriminator.

  The operation of the motor control apparatus configured as described above will be described below with reference to FIG.

Similar to the motor control apparatus of the fifth embodiment, a position detector 102 for detecting the position of the motor is attached to the motor 100, and signals MR1 having a phase of 90 degrees with respect to each other.
, MR2 is output. These MR1 and MR2 signals are corrected by the phase shift amount corrector 504 for each phase difference shift, and then input to the position signal processor 110 to detect the position of the motor. Further, the differentiator 108 detects the motor position. Converted to speed. The speed controller 106 outputs a torque command to the current controller 104 so that the detected speed follows the speed command value, and the current controller 104 supplies the commanded torque to the motor 100. Control the current.

  Next, the phase difference shift correcting operation of the present invention will be described in detail.

  As in the fifth embodiment, the position signals MR1 and MR2 from the position detector 102 have a period difference twice as shown in FIG. The position and speed of the motor determined by the differentiator 110 and the differentiator 108 cause an error that changes every twice the period of the position signal. Therefore, when speed control is performed with a predetermined constant speed command, a fluctuation component having a frequency four times the speed command value ωm, which is the frequency of the position signal, is added to the speed error ωe calculated by the subtractor 112.

  Therefore, a filter that cuts frequency components other than the vicinity of the frequency of the position signal is configured using the filter 600 as a bandpass filter. By passing the speed error ωe through the filter 600, it is possible to extract a component in the vicinity of a frequency that is twice the frequency of the position signal. That is, the component of the speed error generated due to the phase difference deviation can be detected by the value passed through the filter 600, and the phase deviation amount discriminator 602 may use this value as the phase difference judgment value.

  Similarly to the fifth embodiment, this phase difference discriminating value is also adjusted so that there is no deviation in the phase difference of the position signal by adjusting the phase difference discriminator 504 so that the phase difference discriminating value is minimized. It will be possible.

With the above configuration, it is possible to obtain a phase difference discriminating value with a simple filter and correct a phase difference shift, and it is possible to perform accurate motor control even with an inexpensive arithmetic device.

  In the present embodiment, the configuration of the filter is a band pass filter, but any configuration may be used as long as it is a filter that cuts frequency components other than the vicinity of the frequency twice the frequency of the position signal.

  In addition, the value after passing through the filter may include vibration components other than the frequency component of the position signal in the vicinity of twice the frequency of the position signal, but it does not change even if the phase difference is changed. Never become.

  As described above, the motor control device according to the present invention is a position detector that outputs sinusoidal position signals having different phases in order to detect the position of a motor for industrial use or home appliance use. Even when there are phase difference shifts among the plurality of position signals, it can be easily and accurately corrected, and can be applied in a wide range as being capable of accurate control.

DESCRIPTION OF SYMBOLS 100 Motor 102 Position detector 104 Current controller 106 Speed controller 108 Differentiator 110 Position signal processor 112 Subtractor 114, 500 Frequency analyzer 116, 202 Offset amount discriminator 118, 302 Offset corrector 200, 600 Filter 300 Offset Change width storage means 400 Offset coarse adjuster 402 Switch 502, 602 Phase shift amount discriminator 504 Phase shift amount corrector 600 Filter

Claims (6)

In a motor control device having a motor and a position detector that outputs a position signal having a plurality of sinusoidal phases different from each other in phase according to the position of the motor, and the motor outputs a constant signal with a period of one rotation.
Speed detecting means for outputting the rotational speed of the motor from the output of the position detector; and speed control means for controlling the rotational speed of the motor to a predetermined constant speed command value in accordance with the output of the speed detecting means; Have
Frequency analysis means for frequency analysis of a deviation between the output of the speed detection means and the speed command value; and after the rotational speed of the motor is controlled in the vicinity of the speed command value by the speed control means, the output of the frequency analysis means A phase difference discriminating means for outputting a phase difference discriminating value for judging the magnitude of the phase difference between the plurality of position signals of the position detector, and a phase difference for correcting the phase difference of the position detector from the phase difference discriminating value. A motor control device comprising correction means. The phase difference discrimination means calculates the magnitude of the frequency component of the frequency twice the position detector output frequency obtained by multiplying the speed frequency calculated from the speed command value by the sinusoidal cycle of the position detector from the output of the frequency analysis means. The motor control device according to claim 1, wherein the motor control device is extracted to obtain a phase difference determination value. The frequency analysis means has a frequency twice the position detector output frequency obtained by multiplying the deviation between the speed detection means output and the speed command value by the speed frequency calculated from the speed command value and the sinusoidal period of the position detector. 2. The motor control device according to claim 1, wherein a value passed through a filter that removes components other than the vicinity of the component is output. 4. The motor control device according to claim 1, wherein the frequency analysis means analyzes the frequency of the output of the speed control means. The phase difference correction means corrects the phase difference of the plurality of position signals of the position detector by changing the phase difference of the plurality of position signals of the position detector so as to reduce the phase difference determination value. The motor control device according to claim 1. The phase difference correction means stores a plurality of position signals whose phases have been changed in advance, a phase shift position signal storage means, and a position signal of the position detector stored in the phase shift position signal storage means. Phase conversion means for converting to
The phase difference of the plurality of position signals of the position detector is adjusted by changing the phase of the plurality of position signals of the position detector by the phase conversion means so as to reduce the phase difference determination value. The motor control device according to claim 1, wherein: