JP2010110145A - Drive unit of ac motor, and drive control device equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress an influence of an electromotive force generated in an AC motor. <P>SOLUTION: This drive unit of an AC motor is provided with: a feedback control part 13 which outputs a current command value corresponding to a difference between a current command value from a control device 20 and a current value detected by a current detector 17; parts 14, 15 each of which receives a current correction command indicating the current value corresponding to the electromotive force of the motor 30 from the control device 20, adds a current correction command value to the current command value outputted from the feedback control part 13, and outputs a current command value which is obtained by the addition; and a motor driver circuit 16 which feeds a drive current corresponding to the current command value outputted from each of the parts 14, 15 to the motor 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an AC motor drive device that supplies a drive current corresponding to a current command to an AC motor, and a drive control device including the drive device.

  As an AC motor drive device, for example, there is one disclosed in Patent Document 1 below.

  In the drive device disclosed in Patent Document 1, the current values of the drive currents supplied to the U phase, the V phase, and the W phase of the three-phase linear motor are detected, and based on the detected current values of the respective phases, The command current value of the power supplied to the phase is changed. That is, this drive device feedback controls the current values supplied to the U-phase, V-phase, and W-phase of the three-phase linear motor to reduce the error in the actual current value with respect to the current command value.

JP 2005-304121 JP

  In recent years, the linear motor has a large thrust constant for power saving. In the linear motor, when the thrust constant increases, the back electromotive force constant increases accordingly, and the back electromotive force flowing through the power supply line connecting the driving device and the linear motor increases. In recent years, there is a high tendency to move the mover of the linear motor at a high speed, and in this case also, the back electromotive force flowing through the power supply line increases.

  However, when the back electromotive force increases as described above, the position and speed of the motor movable element cannot be accurately controlled only by current feedback control as in the technique described in Patent Document 1 described above. There is.

  The present invention pays attention to such problems of the prior art, and provides a motor drive device and a drive control device including the motor drive device that can more accurately control the position and speed of the motor mover. Objective.

An AC motor drive device according to the invention for solving the above problems is as follows:
In an AC motor drive device that supplies a drive current according to a current command to an AC motor,
A current detector for detecting a current value of a drive current supplied to the AC motor, and a new value indicating a current value according to a deviation between a current value indicated by the current command and a current value detected by the current detector. A current feedback control means for outputting a current command, a current correction command indicating a current value corresponding to a back electromotive force of the AC motor, and a current value indicated by the current command output from the current feedback control means; A current correction command adding means for adding a current value indicated by the current correction command and outputting a current command indicating the current value obtained by the addition; and a current value indicated by the current command output from the current correction command adding means. And a motor drive circuit for supplying a corresponding drive current to the AC motor.

In addition, an AC motor drive control device for solving the above problems is
The above drive device, and a control device that outputs the current command to the current feedback control means of the drive device,
The control device includes:
Using a predetermined relationship between a current command generating means for generating the current command to be output to the current feedback control means, a relative position of the mover with respect to the stator of the AC motor, and the back electromotive force, the mover Current correction command generating means for obtaining a back electromotive force corresponding to position information from a position sensor that detects a relative position of the current and generating the current correction command indicating a current value corresponding to the back electromotive force. Features.

  According to the present invention, since the current value corresponding to the counter electromotive force generated by the AC motor is added to the current command value output from the control device, the position and speed of the motor mover can be controlled more accurately. it can.

  Embodiments of an AC motor drive control apparatus according to the present invention will be described below with reference to the drawings.

  The AC motor that is driven and controlled by the drive control device of the present embodiment is a three-phase linear motor 30 as shown in FIG. The three-phase linear motor 30 includes a load coil that forms a mover or a stator, a permanent magnet (not shown) that forms a stator or a mover, and a position sensor 32 that detects the relative position of the mover with respect to the stator. And have. The load coils include a U-phase coil 31u, a V-phase coil 31v, and a W-phase coil 31w. The terminals on the opposite side of the drive side of each phase coil 31u, 31v, 31w are connected to each other and connected to the ground of the power supply circuit 40.

  The drive control device for driving and controlling the three-phase linear motor 30 described above includes a current command indicating a current value of a drive current supplied to each phase of the three-phase linear motor 30, and a current correction for correcting the current value indicated by the current command. A control device 20 that outputs a command, and a drive device 10 that adjusts the power from the power supply circuit 40 to a drive current according to a current command for each phase and supplies the current to each phase of the three-phase linear motor 30. ing.

  Functionally, the control device 20 includes a current command generation unit 21 that generates the above-described current command and a current correction command generation unit 22 that generates the above-described current correction command. The current correction command generation unit 22 holds an expression indicating the relationship between the relative position of the mover with respect to the stator of the three-phase linear motor 30 and the back electromotive force generated by the three-phase linear motor 30. The back electromotive force generated by the three-phase linear motor 30 is obtained by substituting the relative position of the mover detected by the position sensor 32, and a current correction command indicating a current value corresponding to the back electromotive force is generated.

  The control device 20 is a computer in terms of hardware, and includes a CPU that executes various arithmetic processes, a ROM that stores programs and data executed by the CPU in advance, and a RAM that serves as a work area for the CPU. And an input device such as a keyboard, and an interface for transmitting and receiving signals between the driving device 10 and the three-phase linear motor 30. Each of the aforementioned functional units 21 and 22 of the control device 20 functions when the CPU executes a program stored in a ROM or the like.

  The drive device 10 supplies current to the U-phase drive unit 11u that supplies current to the U-phase coil 31u of the three-phase linear motor 30, the V-phase drive unit 11v that supplies current to the V-phase coil 31v, and the W-phase coil 31w. A W-phase drive unit 11w to be supplied, and a D / A converter 12 that converts a digital signal indicating various commands from the control device 20 into an analog signal.

  Each of the drive units 11u, 11v, and 11w of each phase has a current detector 17 that detects a current value of a drive current supplied to the corresponding phase of the three-phase AC motor 30, and an output from the current detector 17. A new current command indicating a current value corresponding to the deviation between the amplifier 18 to be amplified and the current command value from the control device 20 converted into an analog signal by the D / A converter 12 and the output from the amplifier 18 is output. The current feedback control unit 13, the correction command input unit 14 that receives a current correction command from the control device 20 that has been converted into an analog signal by the D / A converter 12, and the current command value from the current feedback control unit 13, the correction command The current value indicated by the current correction command from the input unit 14 is added to output a new current command, and the current correction command addition unit 15 outputs the current command. The motor drive circuit 16 supplies the corresponding phase of the three-phase linear motor 30 a drive current corresponding to the current command value, and a.

  The current feedback control unit 13 receives the current command from the amplifier U1 and the D / A converter 12, inputs a resistor R1 connected in series to the input end of the amplifier U1, and a resistor R2 connected in parallel to the amplifier U1. And the capacitor C1 connected in series to the resistor R2, the capacitor C2 connected in parallel to the amplifier U1, and the current value detected by the current detector 17, and the input terminals of the resistor R1 and the amplifier U1 And a resistor R3 connected between them. The current feedback control unit 13 is a proportional integration circuit, which is proportional to the deviation between the current value indicated by the current command from the D / A converter 12 and the output from the current value amplifying amplifier 18, and further this deviation. A new current command value is output in proportion to the time integration.

  The correction command input unit 14 receives the current correction command from the amplifier U2 and the D / A converter 12, and also includes a resistor R4 connected in series to the input terminal of the amplifier U2 and a resistor connected in parallel to the amplifier U2. R5.

  The current correction command adding unit 15 receives the current command from the amplifier U3 and the current feedback control unit 13, and also has a resistor R6 connected in series to the input end of the amplifier U3 and a resistor R7 connected in parallel to the amplifier U3. And a current correction command from the correction command input unit 14, and a resistor R8 connected between the resistor R6 and the input end of the amplifier U3.

  The motor driver circuit 16 includes a PWM PWM (Pulse Width Modulation) control circuit (not shown) to which a current command is input from the current correction command adding unit 15, and a PWM control circuit (not shown) for power from the power supply circuit 40. And an output stage circuit that supplies the drive current to the corresponding phase instead of the drive current having a current value corresponding to the output from. Here, a PWM control circuit with high efficiency and low heat generation is used for current value control, but another control circuit such as a linear control circuit may be used instead.

  Next, the operation of the drive control device of this embodiment will be described.

  Assume that the correction command input unit 14 and the current correction command addition unit 15 of the driving device 10 are not provided, and a current command for causing the motor movable element to have a predetermined speed is output from the control device 20. In this case, a current command indicating a current value corresponding to the deviation between the current value indicated by the current command from the control device 20 and the output from the current value amplification amplifier 18 is input to the motor driver circuit 16. The motor driver circuit 16 outputs a drive current corresponding to the current command to the corresponding phase of the three-phase linear motor 30. On the other hand, in the corresponding phase of the three-phase linear motor 30, a counter electromotive force is generated, and this counter electromotive force flows to the driving device 10 side. For this reason, combined power of AC power (drive current) and back electromotive force corresponding to the current command flows between the motor driver circuit 16 and the corresponding phase of the three-phase linear motor 30. As a result, a current having a current value different from the current command value from the control device 20 flows in the corresponding phase, and the current phase also differs from the target phase.

  Thus, since a current having a current value different from the current command value from the control device 20 flows in the corresponding phase of the three-phase linear motor 30, the current feedback control unit 13 corresponds to the current command value from the control device 20. A new current command is output based on the deviation from the current value flowing in the phase. The motor driver circuit 16 outputs a drive current corresponding to the new current command to the corresponding phase of the three-phase linear motor 30. As a result, the mover of the three-phase linear motor 30 finally reaches the target predetermined speed.

  On the other hand, in the present embodiment, that is, in the drive control device having the correction command input unit 14 and the current correction command addition unit 15, the control device 20 outputs a current command for causing the motor movable element to have a predetermined speed. A current correction command indicating a current value corresponding to the counter electromotive force generated when this current command is output is also output.

  Here, a method of generating a current correction command by the correction current command generation unit 42 of the control device 20 will be described.

  In the case of a linear motor, the voltage E generated by the counter electromotive force generated by the linear motor depends on the position s, speed v, and acceleration α of the motor movable element. Also, if the voltage generated by the linear motor is measured when the linear motor mover is moved by some means without supplying power to the linear motor, the voltage due to the counter electromotive force in this moving state is measured. can do.

  For this reason, in a state in which power is not supplied to the linear motor, the linear motor movable element is moved by some means, the voltage generated by the linear motor is measured, and the measured value and the position s of the motor movable element at that time are measured. A function f indicating the relationship between these parameters and the voltage E generated by the back electromotive force can be derived from the velocity v and the acceleration α. It is possible to theoretically derive this function f. However, when the function f is theoretically derived, the voltage due to the counter electromotive force obtained using this function f is generated by an actual linear motor. Since the error from the voltage due to the back electromotive force often becomes relatively large, it is preferable to measure the voltage due to the back electromotive force and derive the function f using this measured value as described above.

  When the function f is determined, the voltage s, the speed v, and the acceleration α of the motor movable element are acquired from the sensor provided in the linear motor 30 to calculate the voltage due to the back electromotive force when acquiring these data. be able to.

  By the way, the linear motor 30 of this embodiment is used for driving a stage. In this stage, the speed and acceleration of the motor movable element are predetermined according to the position of the motor movable element. Therefore, in the present embodiment, the motor mover is moved by some means at a predetermined speed and acceleration according to the position of the motor mover, and the voltage generated in the linear motor 30 at this time is measured. From this measured value and the position s of the motor movable element at that time, g indicating the relationship between the voltage E due to the back electromotive force and the position s of the motor movable element is derived.

  The correction current command generation unit 42 holds this function g, and substitutes the position of the mover detected by the position sensor 32 provided in the linear motor 30 for this function g. Find the electromotive force. Next, the correction current command generation unit 42 obtains a current value corresponding to the back electromotive force, and outputs a current correction command indicating the current value. Here, the function g is held, and the voltage by the counter electromotive force corresponding to the position of the mover is obtained using the function g. However, the voltage by the counter electromotive force at each position of the mover is obtained. It is also possible to store a map indicating the voltage and obtain the voltage by the back electromotive force corresponding to the position of the mover using this map.

  Next, the operation of the drive device 10 having the correction command input unit 14 and the current correction command addition unit 15 will be described.

  The current feedback control unit 13 of the driving device 10 is similar to the above-described case where the correction command input unit 14 and the current correction command addition unit 15 are not provided, and the deviation between the current command value from the control device 20 and the current value flowing in the corresponding phase. Based on the above, a new current command is output. The new current command value includes the current value indicated by the correction current command input from the correction current command generation unit 22 of the control device 20 via the correction command input unit 14, that is, the current value corresponding to the back electromotive force. The correction command adding unit 15 adds the current command and outputs a current command indicating the added current value. The motor driver circuit 16 outputs a drive current corresponding to the current command from the current correction command adding unit 15 to the corresponding phase of the three-phase linear motor 30. At this time, the current supplied to the corresponding phase is the back electromotive force generated when the drive current is supplied to the drive current having the current value corresponding to the current command value from the control device 20 (however, the drive current Is the power plus the reverse flow). For this reason, the current value of the actual drive current supplied to the three-phase linear motor 30 is a value in which the error due to the counter electromotive force is minimized with respect to the current command value from the control device 20.

1 is a configuration diagram of a three-phase linear motor and a drive control device thereof as one embodiment according to the present invention.

Explanation of symbols

10: drive device, 11u: U-phase drive unit, 11v: V-phase drive unit, 11W: W-phase drive unit, 12: D / A converter, 13: current feedback control unit, 14: correction command input unit, 15: current Correction command addition unit, 16: motor driver circuit, 17: current detector, 20: control device, 21: current command generation unit, 22: current correction command generation unit, 30: three-phase linear motor, 31u: U-phase coil, 31v: V-phase coil, 31W: W-phase coil, 32: position sensor, 40: power supply circuit

Claims (2)

In an AC motor drive device that supplies a drive current according to a current command to an AC motor,
A current detector for detecting the current value of the drive current supplied to the AC motor;
Current feedback control means for outputting a new current command indicating a current value according to a deviation between a current value indicated by the current command and a current value detected by the current detector;
Accepting a current correction command indicating a current value corresponding to the back electromotive force of the AC motor, adding the current value indicated by the current correction command to the current value indicated by the current command output from the current feedback control means, Current correction command adding means for outputting a current command indicating a current value obtained by the addition;
A motor drive circuit for supplying a drive current corresponding to the current value indicated by the current command output from the current correction command adding means to the AC motor;
A drive device for an AC motor comprising: A drive device according to claim 1, and a control device that outputs the current command to the current feedback control means of the drive device,
The control device includes:
Current command generating means for generating the current command to be output to the current feedback control means;
Using a predetermined relationship between the relative position of the mover with respect to the stator of the AC motor and the counter electromotive force, the counter electromotive force is obtained in accordance with position information from a position sensor that detects the relative position of the mover. Current correction command generating means for generating the current correction command indicating a current value corresponding to the counter electromotive force;
An AC motor drive control device comprising:

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