JP2005143256A - Motor controlling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform always stable motor control by automatically adjusting the offset of encoder signals, while this deals with a digital controlling device that controls the rotational speed or rotational position of a motor. <P>SOLUTION: This motor controlling device is provided with a first offset adjusting means 103 that adjusts the offset roughly by letting the encoder signals of two phases of the motor 101 follow a reference voltage, and a second offset adjusting means 104 that detects the changes of the voltage level of the output signals of the first offset adjusting means 103 and outputs the finely-adjusted offset so that its median becomes equal to the reference voltage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motor control device that controls a motor including an encoder.

  For controlling the speed or position of the motor, an encoder signal, for example, a magnetized portion of the rotating part of the motor is detected by various sensors, for example, a magnetoresistive element, and the motor is synchronized with each other. A method is known in which a two-phase sine wave signal having different phases is generated, and this signal is processed by an electronic circuit to detect the rotational position of the motor with high resolution and to perform feedback control of the motor (for example, (See Patent Document 1).

  The encoder signal in this case is based on the premise that no offset voltage is generated. Conversely, when the offset voltage is generated in the encoder signal, the control accuracy of the motor deteriorates, or in the worst case, There is a risk that control of the motor may become impossible.

  For this reason, normally, an offset adjusting means for automatically correcting an offset voltage generated in the encoder signal and generating an encoder signal without an offset voltage is used (see, for example, Patent Document 2).

  Here, FIG. 6 shows a configuration of a conventional motor control device including an offset adjusting unit. In FIG. 6, the offset adjusting means is composed of a first offset adjusting means for manually performing offset adjustment and a second offset adjusting means for automatically performing offset adjustment.

  In FIG. 6, reference numeral 101 denotes a motor, and reference numeral 102 denotes a rotation detector that generates two-phase sinusoidal encoder signals MRA <b> 1 and MRB <b> 1 whose phases are different from each other by 90 degrees according to the rotational position of the motor 101. Reference numeral 105 denotes a reference voltage generation circuit that outputs a constant reference voltage Vref. Reference numeral 601 denotes first offset adjusting means, to which the two-phase encoder signals MRA1 and MRB1 and the reference voltage Vref are input. Reference numeral 104 denotes second offset adjusting means, to which the two-phase signals MRA2 and MRB2 output from the first offset adjusting means 601 and the reference voltage Vref are input. A position detection circuit 106 receives the two-phase signals MRA3 and MRB3 output from the second offset adjusting means 104 and the reference voltage Vref. Reference numeral 107 denotes motor control calculation means, which normally performs calculation processing by a microcomputer. A DA converter 108 converts a torque command value output from the motor control calculation means 107 into a torque command signal that is an analog signal. A motor drive circuit 109 drives the motor 101 in accordance with a torque command signal output from the DA converter 108.

  The operation of the motor control device configured as described above will be described. The first offset adjusting means 601 amplifies the two-phase encoder signals MRA1 and MRB1 output from the rotation detector 102 to a necessary amplitude, and manually adjusts the offset to output the signals as two-phase signals MRA2 and MRB2. It has a function. The manual adjustment of the offset is performed at the stage of assembling the motor control device.

Next, details of the first offset adjusting means 601 will be described. First, a detailed configuration of the first offset adjusting unit 601 will be described. In FIG. 6, reference numeral 110 denotes a two-channel inverting amplifier circuit having a function of synthesizing an input signal and an offset correction voltage for correcting an offset included in the input signal. The reference voltage Vref output from the reference voltage generation circuit 105 is input to the input terminal T4. The signal input to the input terminal T1 is the reference voltage V
With reference to ref, the signal is amplified to an amplitude necessary for subsequent signal processing and output to the output terminal T3. The transfer coefficient from the input terminal T1 to the output terminal T3, that is, the amplification gain is usually several tens of times. Similarly, the signal input to the input terminal T5 is amplified with reference to the reference voltage Vref and output to the output terminal T7. The transmission coefficient from the input terminal T5 to the output terminal T7 is the same as the transmission coefficient from the input terminal T1 to the output terminal T3.

  Reference numerals 130 and 131 denote semi-fixed resistors for manually adjusting the offset. The output voltage of the semi-fixed resistors 130 and 131 can be set to any potential between the ground potential and the power supply voltage by manual adjustment. Accordingly, the transmission coefficient from the input terminal T2 to the output terminal T3 and the transmission coefficient from the input terminal T6 to the output terminal T7 are appropriately set in accordance with the offset variation range of the two-phase encoder signals MRA1 and MRB1. Thus, the offsets of the two-phase encoder signals MRA1 and MRB1 can be adjusted by manual adjustment of the semi-fixed resistors 130 and 131, and the median value of these signals can be made substantially coincident with the reference voltage Vref.

  The second offset adjusting means 104 functions on the assumption that the manual adjustment of the offset is completed. The second offset adjusting means 104 has a function of finely adjusting the offset of the two-phase signals MRA2 and MRB2 and outputting the two-phase signals MRA3 and MRB3. The fine adjustment of the offset of the two-phase signals MRA2 and MRB2 is automatically performed while the motor 101 is rotating at a low speed when the power is turned on. When this is completed, the two-phase signals MRA3 and MRB3 become signals that do not include an offset, and the motor 101 can be normally feedback controlled using these signals.

  The two-phase signals MRA3 and MRB3 whose offsets are corrected in this way are input to the position detection circuit 106 and subjected to signal processing. The position detection circuit 106 interpolates this signal and detects the rotational position of the motor 101 with high resolution. Information on the rotational position of the motor 101 detected by the position detection circuit 106 is subjected to arithmetic processing for feedback control of the rotational speed or rotational position of the motor 101 by the motor control arithmetic means 107, and is output as a torque command value. Is done. This torque command value is converted into a torque command signal which is an analog signal by the DA converter 108 and input to the motor drive circuit 109 to drive the motor 101.

The details of the motor control calculation means 107 and the details of the feedback control of the motor described above are as shown in the above-described Patent Document 1 and the like, and are known techniques, and therefore are described here in detail. Is omitted.
Japanese Patent Application Laid-Open No. 09-103086 JP 2000-50664 A

  However, in the configuration as described above, since the variation in characteristics of the rotation detector is corrected by manual adjustment of the semi-fixed resistors 130 and 131 in the first offset adjusting means 601, the correction amount after adjustment is fixed. Therefore, when the characteristics of the rotation detector 102 change over time and as a result, the offset deviation becomes large, or when the rotation detector 102 is replaced due to a failure or the like, manual adjustment is required again. There was a problem of becoming.

In view of the above problems, the motor control device of the present invention includes the first offset adjusting means for automatically converging the variation in the characteristics of the rotation detector within a range in which the problem does not occur. It is an object of the present invention to provide a motor control device that does not require manual adjustment again even when a secular change occurs or the rotation detector is replaced, and that enables stable and highly accurate motor control at all times. .

  A rotation detector that outputs a two-phase encoder signal with different phases according to the rotational position of the motor, and by making the two-phase encoder signal follow a reference voltage to roughly adjust each offset of the two-phase encoder signal First offset adjusting means for outputting, and a change in the voltage level of the output signal of the first offset adjusting means is detected, and each offset is finely adjusted so that the center value becomes equal to the reference voltage, and then output. Two offset adjustment means, and before starting the motor, each offset of the two-phase encoder signal is coarsely adjusted by the first offset adjustment means, and after the completion, while rotating the motor at a low speed , Each offset of the output signal of the first offset adjustment means is finely adjusted by the second offset adjustment means, and after the completion, the second offset adjustment means Feedback control of the motor using the output signal of the facet adjustment means eliminates the need for manual adjustment again regardless of aging or replacement of the rotation detector, and enables stable and highly accurate motor control at all times. Become.

  According to the motor control device of the present invention, even when the characteristics of the rotation detector have changed over time, or even when the rotation detector is replaced, the manual adjustment is not necessary again, and the stable high accuracy is always achieved. The effect that motor control becomes possible is acquired.

  Furthermore, according to the motor control apparatus of the second aspect, the effect that the offset adjustment operation can be completed in a short time can be obtained.

  According to a first aspect of the present invention, there is provided a motor control device, comprising: a rotation detector that outputs two-phase encoder signals having different phases according to the rotational position of the motor; and causing the two-phase encoder signals to follow a reference voltage. First offset adjusting means for coarsely adjusting and outputting each offset of the two-phase encoder signal, and detecting a change in the voltage level of the output signal of the first offset adjusting means, the median of which is the reference voltage By comprising the second offset adjusting means that finely adjusts and outputs each offset to be equal, there is no need for manual adjustment again, and stable high-precision motor control can always be performed. Have.

  The motor control device according to claim 2 of the present invention includes a feedback loop, and includes a first offset adjusting unit that causes the two-phase encoder signal to follow the reference voltage by the action thereof, thereby reliably offset in a short time. The operation of adjusting can be completed.

Embodiments of the present invention will be described below 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 rotation detector that generates two-phase sinusoidal encoder signals MRA1 and MRB1 whose phases are different from each other by 90 degrees in accordance with the rotational position of the motor 101. Reference numeral 105 denotes a reference voltage generation circuit that outputs a constant reference voltage Vref. Reference numeral 103 denotes first offset adjusting means, to which the two-phase encoder signals MRA1 and MRB1 and the reference voltage Vref are input. Reference numeral 104 denotes second offset adjusting means, to which the two-phase signals MRA2 and MRB2 output from the first offset adjusting means 103 and the reference voltage Vref are input. A position detection circuit 106 receives the two-phase signals MRA3 and MRB3 output from the second offset adjusting means 104 and the reference voltage Vref. Reference numeral 107 denotes motor control calculation means, which normally performs calculation processing by a microcomputer. A DA converter 108 converts a torque command value output from the motor control calculation means 107 into a torque command signal that is an analog signal. A motor drive circuit 109 drives the motor 101 in accordance with a torque command signal output from the DA converter 108.

  The operation of the motor control device configured as described above will be described. The first offset adjusting means 103 amplifies the two-phase encoder signals MRA1 and MRB1 output from the rotation detector 102 to a necessary amplitude, and coarsely adjusts the offset to output the signals as two-phase signals MRA2 and MRB2. It has a function. The second offset adjusting means 104 has a function of finely adjusting the offset of the two-phase signals MRA2 and MRB2 and outputting the two-phase signals MRA3 and MRB3. The first offset adjusting means 103 performs coarse adjustment of the offset of the two-phase encoder signals MRA1 and MRB1 before driving the motor 101. When the rough adjustment of the offset is completed, the second offset adjustment unit 104 finely adjusts the offset of the two-phase signals MRA2 and MRB2 while rotating the motor 101 at a low speed. When this is completed, the two-phase signals MRA3 and MRB3 do not include an offset, and the motor 101 can be normally feedback-controlled using the two-phase signals MRA3 and MRB3.

  The two-phase signals MRA3 and MRB3 whose offset has been corrected are input to the position detection circuit 106 and processed. The position detection circuit 106 interpolates this signal and detects the rotational position of the motor 101 with high resolution. Information on the rotational position of the motor 101 detected by the position detection circuit 106 is subjected to arithmetic processing for feedback control of the rotational speed or rotational position of the motor 101 by the motor control arithmetic means 107, and is output as a torque command value. Is done. This torque command value is converted into a torque command signal which is an analog signal by the DA converter 108 and input to the motor drive circuit 109 to drive the motor 101.

  Next, the operation of the first offset adjusting unit 103 will be described in detail. First, a detailed configuration of the first offset adjusting unit 103 will be described. In FIG. 1, reference numeral 110 denotes a two-channel amplifier circuit having a function of combining an input signal and an offset correction voltage for correcting an offset included in the input signal. The reference voltage Vref output from the reference voltage generation circuit 105 is input to the input terminal T4. The signal input to the input terminal T1 is amplified to an amplitude necessary for subsequent signal processing with reference to the reference voltage Vref, and is output to the output terminal T3. The transfer coefficient from the input terminal T1 to the output terminal T3, that is, the amplification gain, is usually about several tens of times. On the other hand, the transfer coefficient from the input terminal T2 to the output terminal T3 is 1. Similarly, the signal input to the input terminal T5 is amplified with reference to the reference voltage Vref and output to the output terminal T7. The transfer coefficient from the input terminal T5 to the output terminal T7 is the same as the transfer coefficient from the input terminal T1 to the output terminal T3, and the transfer coefficient from the input terminal T6 to the output terminal T7 is also the input The transmission coefficient is the same as before.

  An output signal from the output terminal T3 of the amplifier circuit 110 is input to the AD converter 111 and converted from an analog signal to a digital value. The digital value is input to the adjustment control means 113. The output value of the adjustment control means 113 is input to the DA converter 115, converted into an analog signal again, and input to the input terminal T2 of the amplifier circuit 110. Similarly, an output signal from the output terminal T7 of the amplifier circuit 110 is input to the AD converter 112 and converted from an analog signal to a digital value. The digital value is input to the adjustment control means 114. The output value of the adjustment control means 114 is input to the DA converter 116, converted into an analog signal again, and input to the input terminal T6 of the amplifier circuit 110.

  As described above, the first offset adjustment means includes the circuits and signal processing means for two channels corresponding to the two-phase encoder signals. Of these, the circuit and signal processing means for one channel are included. As shown in FIG. Next, details of the adjustment control means 113 shown in FIG. 3 will be described.

  The difference between the encoder signal converted into the digital value by the AD converter 111 and the target value 301 is calculated by the difference calculation means 302. Here, the target value 301 is a value corresponding to the output value of the AD converter 111 when the reference voltage Vref output from the reference voltage generation circuit 105 is input to the AD converter 111. The output of the difference calculation means 302 is integrated by the integration calculation means 303 and then multiplied by a predetermined gain by the gain multiplication means 304. The output of the gain multiplication unit 304 is added to the center value 305 by the addition calculation unit 306 and input to the DA converter 115. In this case, the center value 305 is the same as the target value 301. The output signal of the DA converter 115 is input to the input terminal T2 of the amplifier circuit 110, inverted and amplified by a gain of about 1 with respect to the reference voltage Vref input to the input terminal T4, and output to the output terminal T3. Input to the converter 111.

  As described above, the configuration shown in FIG. 3 forms a feedback loop including an integral element with respect to the signal MRA2, and gives an appropriate gain to the gain multiplication unit 304, thereby allowing the output signal of the amplifier circuit 110 to be output. MRA2 acts so as to follow the reference voltage Vref quickly and without a steady deviation regardless of the voltage of the input signal MRA1. Therefore, even when an offset occurs in the input signal MRA1, a voltage is output from the DA converter 113 to the input terminal T2 so that the output signal MRA2 is forcibly matched with the reference voltage Vref.

  Examples of changes in the output signal MRA2 in this case are shown in FIGS. In the figure, VGND on the vertical axis indicates the ground potential, Vcc indicates the power supply voltage, and Vref indicates the reference voltage. Although power is turned on at time t1, the adjustment control means 113 does not function at this time, and therefore remains at a constant voltage. Thereafter, since the adjustment control means 113 starts the above-described operation at time t2, the signal MRA2 starts to converge to the reference voltage Vref, and almost completes convergence at time t3. Therefore, at time t4, the adjustment control means 113 and 114 fix their output values, and the output voltages of the DA converters 115 and 116 at this time become the offset correction voltages of the respective phases. The coarse offset adjustment operation by the first offset adjustment unit 103 is thus completed.

  Next, the second offset adjusting unit 104 will be described in detail. As shown in FIG. 1, the second offset adjusting means 104 receives the output voltage Vref of the reference voltage generating means 105 and the two-phase signals MRA2 and MRB2 output from the first offset adjusting means 103, and outputs the reference voltage Vref. The offsets of the two-phase signals MRA2 and MRB2 are finely adjusted and output as the two-phase signals MRA3 and MRB3. Various specific configurations of the second offset adjusting means 104 are conceivable. One configuration example is shown in FIG.

  In FIG. 2, reference numeral 120 denotes a two-channel inverting amplifier circuit having a function of synthesizing an input signal and an offset correction voltage for correcting an offset included in the input signal, and is input to input terminals T8 and T9. The signals are combined, inverted and amplified with a gain of 1 with respect to the reference voltage Vref input to the input terminal T11, and output to the output terminal T10. Similarly, signals input to the input terminals T12 and T13 are combined, inverted and amplified with a gain of 1 with respect to the reference voltage Vref, and output to the output terminal T14.

The fine offset adjustment operation performed by the second offset adjustment unit 104 is performed while the motor 101 is rotating at a low speed. That is, the two-phase input signals MRA2 and MRB2 change in a sine wave shape according to the rotation of the motor 101 as shown at times t4 to t5 in FIGS. Suppose that it continues. Thus, the signal MRA2 changing in a sine wave shape is inputted to the input terminal T8 and simultaneously inputted to the AD converter 122 and converted into a digital value. This value is taken in as a difference value with respect to the value of the reference voltage Vref converted to a digital value by the AD converter 121, and the median value of the difference value is detected by the median value detection means 124 at times t4 to t5. In FIG. 4A, the value corresponding to the median is L1, and in FIG. 4C, it is L2. FIG. 4B shows a state in which no offset has occurred.

  Similarly, a signal MRB2 that changes sinusoidally according to the rotation of the motor 101 is input to the input terminal T12 and simultaneously input to the AD converter 123 to be converted into a digital value. This value is taken in as a difference value with respect to the value of the reference voltage Vref converted into a digital value by the AD converter 121, and the median value of the difference value is detected by the median value detection means 125 at times t4 to t5.

  When the detection is completed in this way, the respective median values correspond to the offset voltages of the signals MRA2 and MRB2. The offset voltage thus detected is input as a fixed value to the DA converters 126 and 127, converted from a digital value to an analog signal, and then input to the input terminals T9 and T13. Since the voltage input to the input terminal T9 is combined with the voltage input to the input terminal T8, and the voltage input to the input terminal T13 is combined with the voltage input to the input terminal T12, the signals MRA2 and MRB2 The offset voltage is canceled by the offset correction voltage input to the input terminals T9 and T13, and becomes a signal having no offset. Accordingly, after the fine adjustment of the offset is completed, the output signals MRA3 and MRB3 of the second offset adjusting unit 104 are signals without an offset.

  However, if only the fine adjustment of the offset by the second offset adjustment unit 104 is performed without using the first offset adjustment unit 103, the operation of the offset adjustment is insufficient. For example, when the offsets of the two-phase encoder signals MRA1 and MRB1 are large, the waveforms of the amplified two-phase signals MRA2 and MRB2 are saturated to VGND or Vcc as shown in FIGS. This is because there is a possibility of being distorted. If feedback control of the motor 101 is performed in this state, the control accuracy is deteriorated. In this case, when the first offset adjusting means 103 is operated at time t2 in the state of FIG. 5A, it converges to the reference voltage Vref at time t3 as shown in FIG. 5C. Therefore, the waveforms of the amplified two-phase signals MRA2 and MRB2 are not saturated and distorted, and the motor 101 can be feedback controlled with high accuracy.

  When the reference voltage Vref is set to ½ of the power supply voltage Vcc, the amplitudes of the amplified two-phase signals MRA2 and MRB2 need to be smaller than the reference voltage Vref. If this is exceeded, the waveform of the amplified two-phase signals MRA2 and MRB2 may be saturated and distorted even when the first offset adjusting means 103 is activated.

  As described above, after the power is turned on, first, the first offset adjusting unit 103 coarsely adjusts the offset of the two-phase encoder signal, and after the completion, the second offset adjusting unit 104 finely adjusts the offset. By performing the adjustment, the two-phase encoder signal can be automatically made an offset-free signal. Therefore, no manual adjustment is required again regardless of the secular change of the rotation detector 102, etc. The effect that the motor 101 can be feedback-controlled with high accuracy is obtained.

  The details of the motor control calculation means 107 and the details of the feedback control of the motor described above are as described in Patent Document 1 as described above, and are known techniques. Description is omitted.

The motor control device of the present invention is equipped with means for automatically adjusting the offset of the rotation detector, and is always stable and highly accurate motor control even in applications with somewhat adverse environments such as large temperature changes and large vibrations. Is possible.

The figure which shows 1st embodiment of this invention The figure which shows the structure of a 2nd offset adjustment means. The figure which shows the structure of a 1st offset adjustment means. The figure which shows the output signal of a 2nd offset adjustment means The figure which shows another output signal of a 2nd offset adjustment means The figure which shows embodiment of a prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Motor 102 Rotation detector 103 1st offset adjustment means 104 2nd offset adjustment means 105 Reference voltage generation circuit 106 Position detection circuit 107 Motor control calculation means 108 DA converter 109 Motor drive circuit 110 Amplifier circuit 111, 112 AD converter 113 , 114 Adjustment control means 115, 116 DA converter

Claims (2)

A rotation detector that outputs a two-phase encoder signal with different phases according to the rotational position of the motor, and by making the two-phase encoder signal follow a reference voltage to roughly adjust each offset of the two-phase encoder signal First offset adjusting means for outputting, and a change in the voltage level of the output signal of the first offset adjusting means is detected, and each offset is finely adjusted so that the center value becomes equal to the reference voltage, and then output. Two offset adjustment means, and before starting the motor, each offset of the two-phase encoder signal is coarsely adjusted by the first offset adjustment means, and after the completion, while rotating the motor at a low speed , Each offset of the output signal of the first offset adjustment means is finely adjusted by the second offset adjustment means, and after the completion, the second offset adjustment means Motor controller for feedback controlling the motor using the output signal of the offset adjusting means. The motor control device according to claim 1, further comprising a first offset adjusting unit that includes a feedback loop and causes the two-phase encoder signal to follow the reference voltage by its action.

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