JP2006033903A - Motor control device - Google Patents

Abstract

An inexpensive motor control device capable of high-precision motor control even when an analog signal transmission distance is long is provided.
In a motor control device comprising a motor and a drive circuit that calculates a drive command to the motor from a rotational position detection signal of the motor, the drive circuit 3 outputs an analog signal of the position detection means 2 synchronized with the rotation of the motor 1. A noise removing unit 31 that corrects an influence of noise and attenuation of the analog signal as an input, and a phase correcting unit 32 that corrects a phase delay caused by the noise removing unit 31 according to the rotation speed of the motor 1 are provided. Based on the 32 corrected phases, the drive command generating means 33 generates a drive command and switches the inverter circuit 34.
[Selection] Figure 1

Description

  The present invention relates to a motor control device that controls the speed and position of a motor used for general industrial applications.

  In general, a brushless motor is required to have a rectangular wave drive system that detects the position of a motor by an output logic of a commutation sensor (hereinafter referred to as CS) that generates a signal corresponding to the magnet position of the rotor, and high control accuracy. In this case, the sensor is driven by a sine wave driving method in which the rotation position of the motor is calculated using the CS signal logic and the position information detected by the encoder using a sensor such as an optical encoder.

  However, the former method has low control accuracy because it can obtain resolution only by the number of points at which the logic of the CS signal is switched. In addition, the latter method generally requires an IC, a high-precision encoder, and the like, and thus has a problem of cost.

On the other hand, a method for correcting the analog value of the magnetic pole signal has been proposed as means for detecting the rotational position of the motor with low cost and accuracy without using an expensive detector such as an optical encoder (for example, Patent Documents). 1).
JP 2003-158888 A

  However, when an analog signal is used for detecting the position of the motor, disturbance due to noise occurs, and it is difficult to accurately control the motor.

  In particular, if the cable between the motor and the control circuit is extended and the signal transmission distance is increased, such disturbance of the analog signal increases, so that it is difficult to control the rotational position of the motor as it is.

  In the case of a digital signal, control is not affected even if noise is superimposed on a part other than where the logic changes, and noise countermeasures can be performed relatively easily by digital filter processing or the like.

  On the other hand, in the case of an analog signal, since the signal that changes every moment represents the magnetic pole position of the motor in real time, it is difficult to take measures against noise compared to the case of a digital signal.

  For example, in the case of a sinusoidal signal, the angle is calculated by solving the inverse trigonometric function and the motor position is detected, so if noise is superimposed and the signal is disturbed, the effect is directly reflected in the calculation result of the motor position detection. Appears and deviates from the actual motor position, and accurate motor control cannot be performed.

  Generally, it is conceivable to install a low-pass filter in the analog signal transmission line as a noise countermeasure. However, when the motor rotation speed increases, the phase delay of the analog signal due to the filter time constant becomes significant, and the angle information of the analog signal is used. Since the generated drive command to the motor and the actual motor rotation position are shifted, accurate position control cannot be performed.

The present invention solves the above-mentioned conventional problems, and enables high-precision motor control even when the distance between the motor and the control circuit is extended with a cable or the like and the analog signal transmission distance becomes long. An object is to provide an inexpensive motor control device.

  In order to solve the above problems, the motor control device of the present invention removes the noise of the analog signal output from the position detecting means synchronized with the rotation of the motor by the noise removing means, and further reduces the phase delay of the analog signal by the phase correcting means. Because it is equipped with a correction means, it is possible to transmit analog signals to the drive circuit with high accuracy and perform high-precision motor control, and it is possible to realize it at low cost because an expensive detector such as an encoder is unnecessary. It is.

  According to the motor control apparatus of the present invention, since the phase correction means for correcting the phase delay of the analog signal by the noise removal means according to the rotation speed of the motor is provided, the signal between the motor and the drive circuit is extended by a cable or the like. Even when the transmission distance becomes long, an analog signal can be accurately transmitted to the drive circuit. Further, this phase correction means can correct the phase delay of the analog signal and simultaneously correct the arithmetic processing delay of the drive circuit.

  In addition, Hall elements, MR elements, resolvers, etc. that output analog signals corresponding to the magnetic pole position of the magnet can be used as position detection means, and can be configured at low cost without using expensive encoders, etc. And the position can be accurately controlled.

  In a motor control device comprising a motor and a drive circuit that calculates a drive command to the motor from a rotation position detection signal of the motor, the drive circuit receives an analog signal of position detection means that is synchronized with the rotation angle of the motor. A noise removing unit that removes an influence of signal noise; and a phase correcting unit that corrects a phase delay caused by the noise removing unit according to a rotational speed of the motor, and a drive command based on the phase corrected by the phase correcting unit. The generation means is a motor control device that generates a drive command and switches the inverter circuit.

  FIG. 1 is a schematic block diagram of a motor control device of the present invention.

  The motor 1 is, for example, a multiphase synchronous motor such as a three-phase brushless motor, a stepping motor, or a linear motor, and a position detection unit 2 is provided in the vicinity thereof.

  The position detection means 2 outputs an analog signal synchronized with the rotation of the motor 1 and is used as a sensor for detecting the rotation position of the motor 1.

  For example, it can be realized by a detector that detects the magnetic pole position of the motor 1 and outputs a corresponding sinusoidal analog voltage signal, such as a Hall element, MR element, or resolver.

  The analog signal output from the position detection means 2 is transmitted to the drive circuit 3 via the sensor signal cable 5. If the analog signal is affected by disturbance due to external noise or attenuation by cable resistance in the process of passing through the sensor signal cable 5, the accurate motor rotation position cannot be transmitted.

  In order to remove such noise and attenuation and maintain the accuracy of the analog signal, the drive circuit 3 is provided with noise removing means 31 to remove the influence of noise.

  FIG. 2 is an explanatory diagram of the noise removing means 31. For example, the noise removing unit 31 can be configured at low cost by the low-pass filter 10 including the resistor 11 and the capacitor 12.

  If noise is superimposed before the low-pass filter 10, the sensor signal 17 before the filter cannot be used to detect the rotational position of the motor 1, but the noise is removed from the sensor signal 18 after filtering via the low-pass filter 10. A sine wave waveform synchronized with the rotation of the motor 1 can be used for position detection.

  However, the analog sine wave signal that has passed through the noise removing means 31 causes a phase delay due to the time constant of the low-pass filter 10. If there is a phase lag, the actual position of the motor 1 is not correctly detected because the drive command such as a voltage command or a current command generated based on the angle information of the analog sine wave signal is shifted from the actual position of the motor 1.

  FIG. 3 is a diagram for explaining the phase lag that occurs in the analog signal before and after the noise removing means 31. It can be seen that the post-filter sensor signal 18 is out of phase by a phase lag 16 compared to the pre-filter sensor signal 17.

When the resistance value of the resistor 11 is R and the capacitance of the capacitor 12 is C, the time constant T is expressed as T = C × R, and when the frequency of the analog sine wave is ω, the transfer function G = 1 / of this filter. Since (1 + jωT) and the phase delay ∠G = −tan ⁻¹ ωT, the phase delay ∠G is proportional to the frequency ω of the sine wave, that is, the rotational speed of the motor.

  Since the influence of the phase delay becomes more prominent as the motor rotates at a higher speed, the motor control device includes a phase correction unit 32 that corrects the phase in proportion to the rotation speed of the motor.

  The phase correction means 32 is stored in the microcomputer 7 as a control algorithm, and can be realized by setting a proportionality constant in advance as a parameter and advancing the phase of the drive command value in accordance with the gradient based on the proportionality constant.

  In addition, since the delay of calculation processing by the microcomputer 7 also increases in proportion to the rotation speed of the motor 1, it is possible to correct simultaneously including the delay of the calculation processing system by considering the setting of the proportional constant. Is also possible.

  The drive command generation unit 33 generates a drive command whose phase is shifted by the amount of phase correction by the phase correction unit 32 and rotates the motor 1 by switching the inverter circuit 34.

  The drive command may be, for example, a voltage command applied to the motor winding, or a current command when current control is possible using a current sensor or the like.

  Even if the signal transmission distance becomes long, such as by extending the sensor signal cable 5 by the noise removing means 31 and the phase correcting means 32 described above, it is possible to take sufficient noise countermeasures, and at the same time, the motor 1 accurately without phase delay. Position information can be transmitted to the drive circuit 3, and high-precision motor control can be performed.

The motor control device of the present invention has a drive circuit and a motor separately installed in general industrial equipment such as a transfer device, a switching device, and a semiconductor manufacturing device, and is connected to the motor with a cable of, for example, several tens of meters. When using in a state where the signal transmission distance between circuits is long, high speed stability and high-accuracy positioning control can be realized only with an inexpensive sensor such as a Hall element without using an expensive position detector. Is possible.

1 is a schematic block diagram of a motor control device according to a first embodiment of the present invention. Configuration diagram showing an example of noise removing means Illustration of phase lag

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Position detection means 3 Drive circuit 5 Sensor signal cable 7 Microcomputer 8 Motor cable 10 Low-pass filter 11 Resistor 12 Capacitor 16 Phase delay 17 Sensor signal before filter 18 Sensor signal before filter 31 Noise removal means 32 Phase correction means 33 Drive command Generation means 34 Inverter circuit

Claims (3)

In a motor control device comprising a motor and a drive circuit that calculates a drive command to the motor from a rotation position detection signal of the motor, the drive circuit receives an analog signal of position detection means that is synchronized with the rotation angle of the motor. A noise removing unit that removes an influence of signal noise; and a phase correcting unit that corrects a phase delay caused by the noise removing unit according to a rotational speed of the motor, and a drive command based on the phase corrected by the phase correcting unit. The generation means generates a motor drive command and switches the inverter circuit. The motor control device according to claim 1, wherein the phase correction means simultaneously corrects the arithmetic processing delay of the drive circuit. 2. The motor control device according to claim 1, wherein a Hall element, MR element or resolver is used as the motor position detecting means.