JP2005160243A - Motor control arrangement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable and excellent rotational fluctuation characteristics at always by settling fluctuation in the rotational fluctuation characteristics, related to a motor control arrangement equipped with a fine speed controlling function. <P>SOLUTION: A control calculation cycle setting means 107 is provided to vary the cycle of a control calculation means 103 according to the fine control value of speed command. Thus, the speed is fine controlled without degrading the rotational fluctuation characteristics. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motor control device that controls the rotational speed or rotational position of a motor.

  For example, in an image forming apparatus such as a copying machine, when a motor directly drives a photosensitive member without a gear or the like, the rotational speed of the motor is often relatively low, such as several tens (r / min). . In such a case, as a motor control method employed, a method of performing control arithmetic processing at a predetermined constant cycle is generally used (see, for example, Patent Document 1). However, since the rotation speed of the motor is low, a torque fluctuation factor such as cogging of the motor itself or torque ripple causes a remarkable rotation unevenness component with a repetition cycle synchronized with the rotation of the motor.

  However, in the image forming apparatus, it is necessary to rotate the photoconductor with low rotation unevenness in order to improve print quality. Therefore, by providing a compensator including N (N is a positive integer) series-connected memory group in the feedback control loop, a means for reducing the rotation unevenness of the above-described repetition cycle may be adopted. Yes (see, for example, Patent Document 2). Further, there is a method of detecting the rotational position of the motor with high resolution by interpolating the sensor signal (see, for example, Patent Document 3).

  FIG. 5 shows the configuration of a conventional motor control device.

  The configuration of the conventional motor control device shown in FIG. 5 is the same as that of the embodiment of the present invention shown in FIG. 1, and only the differences will be described. Reference numeral 502 denotes an addition unit that adds the reference value of the speed command and the fine adjustment value of the speed command and outputs the result to the control calculation unit 103. Reference numeral 501 denotes a control calculation cycle setting means, but the detailed configuration is different from that of FIG.

  In FIG. 6, 303 is an interrupt cycle setting means, which is exactly the same as the interrupt cycle setting means 303 in FIG. 3 of the present invention, and is an interrupt cycle for starting the arithmetic processing of the control arithmetic means 103 according to the value of the reference cycle. Set. In this case, since the value of the reference period is a fixed value, the period in which the calculation process of the control calculation unit 103 is executed is also fixed.

The motor control device configured as described above forms a feedback control loop for controlling the rotation speed of the motor 101 to match the value of the speed command. The speed gain multiplication means 125 and the position gain multiplication means 126 By giving appropriate values to the respective gains, the rotational speed of the motor 101, that is, the value obtained by differentiating the output of the position detecting means 102 is matched with the value obtained by adding the fine value of the speed command to the reference value of the speed command. Be controlled. Therefore, the rotational speed of the motor 101 can be finely adjusted by fixing the reference value of the speed command and changing the fine adjustment value of the speed command.
JP 2003-9564 A JP 63-80783 A Japanese Patent Application Laid-Open No. 09-103086

However, in the above-described conventional configuration, since the processing of the control calculation means and the compensator is executed at a predetermined fixed period, the speed command is changed from the reference value to finely adjust the rotation speed of the motor. Then, the frequency of the rotation unevenness of the motor also changes according to the change of the rotation speed of the motor. Therefore, a deviation occurs between the frequency of the motor rotation unevenness and the frequency at which the compensator acts to suppress the rotation unevenness. As a result, the effect of the compensator decreases, that is, the motor rotation unevenness deteriorates. there were.

  The present invention solves such a conventional problem, and provides a motor control device that exhibits good motor control performance without deteriorating rotational unevenness even when the rotational speed of the motor is finely adjusted. The purpose is to do.

  In order to solve the above-mentioned problems, the present invention relates to a position detection means for detecting the rotational position of a motor, the output value of the position detection means, and the rotational speed of the motor obtained by differentiating the value is a speed command. A control arithmetic means for performing arithmetic processing for feedback control that operates so as to match a reference value, an output value of the control arithmetic means, and a compensator that outputs by performing predetermined processing and an output value of the control arithmetic means Control for varying the period for performing the arithmetic processing of the control arithmetic means according to the fine adjustment value of the speed command and the motor driving means for driving the motor according to the added value, the adding means for adding the output value of the compensator Arithmetic cycle setting means.

  According to the motor control device of the present invention, there is an advantageous effect that even when the rotation speed of the motor is finely adjusted, the rotation unevenness does not change. Further, since the rotation unevenness of the repetition cycle inherent to the motor is suppressed, an effect that extremely good rotation unevenness performance is maintained can be obtained.

  The invention according to claim 1 of the present invention is a position detection means for detecting the rotational position of the motor, and an output value of the position detection means, and the rotational speed of the motor obtained by differentiating the value is a speed command. The control arithmetic means for performing arithmetic processing for feedback control that operates so as to match the reference value of the control, the output value of the control arithmetic means, the compensator for outputting by performing predetermined processing, and the output value of the control arithmetic means Adding means for adding the output value of the compensator, motor driving means for driving the motor in accordance with the added value, and a cycle for executing the arithmetic processing of the control arithmetic means in accordance with the fine adjustment value of the speed command. And a control calculation cycle setting means, and has the effect of making it possible to finely adjust the rotation speed of the motor without changing the rotation unevenness.

  In a second aspect of the present invention, the compensator includes N (N is a positive integer) memory groups connected in series, and outputs a value delayed by N samples by the memory groups. The process of adding the output value and the input value and inputting the value again into the memory group is executed at a cycle Q times (Q is a positive integer) the cycle of performing the calculation process of the control calculation means. It has the effect of suppressing the rotation unevenness of the repetitive cycle and making it possible to finely adjust the rotation speed of the motor while maintaining a very good rotation unevenness performance.

  Hereinafter, more specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a motor control apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a motor, and reference numeral 102 denotes a position detection unit that outputs a value indicating the rotational position of the motor 101. Further, the position detection means 102 generates a two-phase sine wave signal that is 90 degrees out of phase with each other according to the rotation of the motor 101, and a signal for converting the output signal of the sensor 111 into a digital value indicating the rotation position of the motor 101. It is comprised by the conversion means 112. The sensor 111 is composed of, for example, a magnetoresistive element, and the signal conversion unit 112 detects, for example, the rotational position of the motor with high resolution by interpolating the sensor signal as disclosed in Patent Document 3. The method etc. are mentioned.

  Reference numeral 103 denotes control calculation means. Inside the control calculation means 103, for example, a calculation process described below is executed by a microcomputer. The output value of the position detection unit 102 taken into the control calculation unit 103 at a predetermined timing is differentiated by the differentiation unit 121 to become a value corresponding to the rotation speed of the motor 101. After this difference is calculated by the difference calculation means 124 from the reference value of the speed command, that is, a speed error, the speed gain multiplication means 125 multiplies the value by a predetermined speed gain. The reference value of the speed command is integrated by the integrating means 122 and becomes a value corresponding to the position command. This difference is calculated by the difference calculating means 123 from the difference from the output value of the position detecting means 102, that is, the position error. After that, the position gain multiplication means 126 multiplies a predetermined position gain. The output value of the speed gain multiplication means 125 and the output value of the position gain multiplication means 126 are added by the addition means 127 and then output as the output value of the control calculation means 103.

  The output value of the control arithmetic unit 103 is input to the compensator 105. The output value of the compensator 105 is combined with the output value of the control arithmetic unit 103 by the adding unit 106 and then input to the motor driving unit 104 as a torque command value. The motor driving means 104 generates a driving torque by driving a current proportional to the input torque command value to the motor 101 to drive the motor 101. The motor drive unit 104 includes a current detection unit 133 that detects a current flowing through the motor 101, a current control unit 131 that performs a current control calculation so that a current corresponding to a torque command value flows through the motor 101, and a current through the motor 101. It is comprised by the drive stage 132 which supplies this. Reference numeral 107 denotes control calculation cycle setting means, which variably sets the cycle for executing the calculation processing of the control calculation means 103 according to the fine adjustment value of the speed command.

  As described above, in the motor control device shown in FIG. 1, a feedback control loop for controlling the rotation speed of the motor 101 to match the reference value of the speed command is formed. By giving appropriate values to the speed gain and the position gain of the position gain multiplying means 126, the rotational speed of the motor 101 is controlled to match the reference value of the speed command.

  Next, details of the compensator 105 will be described. FIG. 2 is a diagram illustrating a detailed configuration of the compensator 105. In FIG. 2, 201 is an input filter, 202 is an adding means, 203 is a group of N memories, 204 is a stabilization filter, and 205 is a phase advance means.

  The value input to the compensator 105 is first input to the input filter 201. The output value of the input filter 201 is added to the output value of the stabilization filter 204 by the adding means 202 and then input to N (N is a positive integer) memory group 203 connected in series. The N memory groups 203 connected in series have a function of sequentially shifting the input values in series for each process. Therefore, the input value is delayed by N processing times by the N memory groups 203 and output through the stabilization filter 204. The output value of the stabilization filter 204 becomes the output of the compensator 105 after the phase is advanced by a predetermined time by the phase advance means 205. Here, both the input filter 201 and the stabilization filter 204 are low-pass filters, and as shown in FIG. 1, in order to ensure the stability of the feedback control when the compensator 105 is incorporated in the feedback control loop. Is. Similarly, the phase advance means 205 is for ensuring the stability of the feedback control.

  In FIG. 2, the input filter 201 and the phase advance means 205 are subjected to arithmetic processing at the same cycle as the control arithmetic means 103 in FIG. The arithmetic processing is executed at a cycle of 103 times the arithmetic processing cycle 103 (Q is a positive integer), that is, 1 / Q frequency division. Therefore, if the cycle in which the calculation processing of the control calculation means 103 is executed is T, the cycle in which the processing block 206 is executed is QT, and the value input to the memory group 203 is delayed by the memory group 203. The time required for one cycle until input to the memory group 203 is NQT. When the reciprocal of this is the frequency fL, the relationship fL = 1 / (NQT) is established. Since a loop is formed in which the output of the memory group 203 returns to the input of the memory group 203 as described above, only the frequency component that is an integer multiple of this frequency f is included in the memory group. At the same time as it is stored in 203, it is sequentially output.

  Thus, the compensator 105 incorporated in the feedback control loop of the motor control device compensates the periodic fluctuation component of the torque command at a frequency that is an integral multiple of the frequency fL, and suppresses the periodic disturbance. Demonstrate the effect.

  In general, the rotation unevenness that occurs when the motor is rotated is caused by a motor-specific torque fluctuation factor related to the structure of the motor itself, that is, the number of magnetized magnetic poles, and the like. Unevenness occurs. Therefore, by setting fL so that the above fL coincides with this fw or has an integral multiple relationship with each other, the rotation unevenness due to the torque fluctuation factor can be suppressed, and a very good rotation unevenness characteristic can be obtained. . As an example, when the rotational speed of the motor is 60.0 (r / min), fw = 1.00 (Hz), N = 250, Q = 4, and T = 1/1000 (seconds). FL = 1.00 (Hz), which is equal to fw, the effect of suppressing the rotation unevenness of the compensator 105 is exerted, and a very good rotation unevenness characteristic can be obtained.

  However, when speed fine adjustment is performed, for example, in the above example, if the rotational speed is increased by 1% and 60.6 (r / min), then fw = 1.01 (Hz) and fL = 1.00 ( Hz), causing uneven rotation characteristics. Therefore, if the period T is changed and T = 1/1010 (seconds), fL = 1.01 (Hz), which is equal to fw = 1.01 (Hz), so that a favorable rotation unevenness characteristic is obtained again. I can do it.

  In this case, the cycle T in which the control calculation is executed is varied by the action of the control calculation cycle setting means 107. A detailed configuration of the control calculation cycle setting means 107 is shown in FIG. The fine value of the speed command is input to the speed cycle conversion unit 301, converted from speed to cycle by calculation, and then multiplied by a predetermined constant to be converted into a value corresponding to the interrupt cycle. The output value of the speed cycle conversion unit 301 is added by the adding unit 302 to the reference cycle, that is, the interrupt cycle when the fine adjustment value of the speed command is zero, and then input to the interrupt cycle setting unit 303. The interrupt cycle setting unit 303 sets an interrupt cycle for starting the calculation process of the control calculation unit 103 according to the input value.

FIG. 4A to FIG. 4B show how the arithmetic processing of the control arithmetic means 103 is started by the interrupt processing set by the control arithmetic cycle setting means 107 in this way. 4A to 4B, reference numerals 401 to 405 denote arithmetic processing of the control arithmetic unit 103 activated by the interrupt. As shown in FIG. 4A, after time t1, interrupts are generated at regular intervals of time t2, t3... And period T, and at the same time, the output of the position detecting means 102 is taken in by the control arithmetic means 103. Arithmetic processing is executed. In the figure, reference numerals 406 and 407 denote arithmetic processing of the processing block 206 in the compensator 105 when Q = 4. Thus, the arithmetic processing of the processing block 206 in the compensator 105 is executed at a rate of one out of the four interrupts, that is, by 1/4 division. FIG. 4B shows a case where the above interrupt period is slightly increased compared to FIG. 4A.

  The rotational speed S of the motor 101 has a relationship of S = C / T with respect to the value C of the speed command. If the reference value of the speed command is Cr and the fine adjustment value of the speed command is Ct, the configuration shown in FIG. Thus, if C = (Cr + Ct), S = (Cr + Ct) / T. Therefore, the rotational speed S is normally changed by changing the fine adjustment value Ct of the speed command. However, in the embodiment of the present invention shown in FIG. 1, the rotational speed S of the motor is finely adjusted by varying the period T. In this case, S = Cr / (Tr + Tt), Tr is a fixed value, and Tt is changed. Substituting for this equation with Tt = −Tr × Ct / (Cr + Ct), it can be seen that S = Cr / (Tr + Tt) = (Cr + Ct) / Tr. Therefore, it can be seen from this calculation result that the same fine speed adjustment is possible by changing Tt, that is, by changing the period T.

  In this way, the rotation speed of the motor 101 can be finely adjusted by the control calculation cycle setting means 107, and even when the rotation speed of the motor 101 is finely adjusted, a stable rotation unevenness characteristic can always be obtained.

  When the calculation process of the compensator 105 is executed at a timing that is not synchronized with the calculation process of the control calculation unit 103, that is, when the value Q indicating the relationship between the execution cycles is not an integer, the frequency fw Even if the frequencies fL coincide with each other, it is not preferable because an uneven rotation component of the frequency (beat) of the difference between the frequencies (reciprocal of the cycle) of each calculation processing appears and the uneven rotation characteristic deteriorates. Therefore, as described above, it is desirable to execute the calculation process of the compensator 105 at a timing synchronized with the calculation process of the control calculation unit 103.

  As described above, with the above-described configuration, even when the motor rotation speed is finely adjusted, a stable and excellent rotation unevenness characteristic can always be obtained.

  The motor control device of the present invention has an effect of maintaining extremely good rotation unevenness even when the rotation speed of the motor is finely adjusted. For example, in an image forming apparatus or the like, a photoconductor is directly driven at a low speed. It is useful in applications that require fine adjustment of the speed.

The block diagram which shows the structure of the motor control apparatus in the Example of this invention. The block diagram which shows the detailed structure of the compensator in the Example of this invention The block diagram which shows the detailed structure of the control calculation period setting means in the Example of this invention. The figure for demonstrating the execution timing of each process of the control calculating means and compensator in the Example of this invention Block diagram showing the configuration of a conventional motor control device The block diagram which shows the detailed structure of the control calculation period setting means in the conventional motor control apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Motor 102 Position detection means 103 Control calculation means 104 Motor drive means 105 Compensator 106, 127, 202, 302, 502 Addition means 107, 501 Control calculation period setting means 111 Sensor 112 Signal conversion means 121 Differentiation means 122 Integration means 123, 124 Difference calculation means 125 Speed gain multiplication means 126 Position gain multiplication means 131 Current control means 132 Drive stage 133 Current detection means 201 Input filter 203 Memory group 204 Stabilization filter 205 Phase advance means 206 Processing block 301 Speed cycle conversion means 303 Interrupt period Setting means 401 to 407 Arithmetic processing N, Q Positive integer T Calculation processing cycle S Rotational speed t Time C Speed command value Cr Speed command reference value Ct Speed command fine adjustment value fL, fw Frequency

Claims (2)

Position detection means for detecting the rotational position of the motor, and feedback control that acts so that the rotational speed of the motor obtained by taking the output value of the position detection means and differentiating the value matches the reference value of the speed command Control arithmetic means for performing arithmetic processing for the control, an output value of the control arithmetic means, a compensator for performing predetermined processing and output, and an adding means for adding the output value of the compensator to the output value of the control arithmetic means And a motor control unit for driving the motor according to the added value and a control calculation cycle setting unit for varying the cycle for executing the calculation process of the control calculation unit according to the fine adjustment value of the speed command. . The compensator includes N memory groups (N is a positive integer) connected in series, outputs a value delayed by N samples by the memory group, and simultaneously adds the output value and the input value. The motor control device according to claim 1, wherein the process to be input again to the memory group is executed at a cycle of Q times (Q is a positive integer) the cycle of performing the calculation process of the control calculation unit.