JP5711560B2 - Motor control device - Google Patents

Description

  The present invention relates to a motor control device, and more particularly to a motor control device that performs tandem control in which the same shaft is driven by a plurality of motors.

  In a machine tool or the like, when the movable part to be moved is large and the moving shaft cannot be driven by only one motor, the same command is given to the two motors, and the movable part (same axis) ) Is driven by two motors.

  FIG. 3 is a diagram showing a control block for performing tandem control by two conventional motors. In this figure, two motors (master axis motor and slave axis motor) not shown in this figure are driven and controlled by the master axis current command and slave axis current command calculated by the current control units 33M and 33S, respectively. .

  First, the operation on the master axis and slave axis will be described. In the master axis, a speed command value Vm * is calculated by the position control unit 31M from the position command value P * and the position feedback Pm, and the speed control unit 32M performs PI from the calculated speed command value Vm * and the speed feedback Vm. Calculation such as control is performed to calculate a torque command value Tm *. The current control unit 33M calculates a master shaft current command from the torque command value Tm * and the current feedback Im, and drives and controls the master shaft motor. The torque command value Tm * calculated by the speed control unit 32M is passed to the torque arbitration unit 35 through the inverter 34. Here, the inverter 34 is used to invert the sign according to the rotation directions of the master axis motor and the slave axis motor. When the rotation directions are the same, the sign is not inverted and the rotation directions are different. In this case, the sign is inverted. Next, in the slave axis, the speed command value Vs * is calculated by the position control unit 31S from the same position command value P * and position feedback Ps as in the master axis, and the calculated speed command value Vs * and speed feedback Vs are calculated. Then, the speed control unit 32S performs operations such as PI control to calculate the torque command value Ts *. The torque arbitration unit 35 calculates an arbitration torque command value Ts1 * from the torque command value Ts * and the torque command value Tm * from the master shaft. A slave shaft current command is calculated from the arbitration torque command value Ts1 * and the current feedback Is, and the drive control of the slave shaft motor is performed.

  Next, the processing in the torque adjuster 35 will be described in detail with reference to FIG. The torque arbitration unit 35 performs a filtering process on the difference between the torque command value Tm * for the master axis and the torque command value Ts * for the slave axis, and calculates an arbitration torque command value Ts1 *. That is, by multiplying the value obtained by subtracting the previous torque arbitration value Ta * from the difference in torque command values (Tm * −Ts *), and adding the previous torque arbitration value Ta *, the current torque Arbitration value Ta * is calculated. In these processes, if the difference between the torque command value for the master axis and the torque command value for the slave axis and the torque arbitration value are Td (n) and Ta * (n), respectively,

Ta * (n) = K * (Td (n) −Ta * (n−1)) + Ta * (n−1) Equation 1
It is represented by However, Ta * (n−1) represents the previous torque mediation value. From Equation 1, the arbitration torque command value Ts1 * of the slave axis is
Ts1 * = Ts1 * (n) = Ta * (n) + Ts * (n)
= K * (Td (n) -Ta * (n-1)) + Ta * (n-1) + Ts * (n)
= K * ((Tm * (n) -Ts * (n))-Ta * (n-1)) + Ta * (n-1) + Ts * (n) Equation 2
It becomes. Here, the torque arbitration value Ta * (n) is corrected so that the torque command value Ts * (n) of the slave shaft approaches the same value as the torque command value Tm * (n) of the master shaft. A value obtained by subtracting the previous torque arbitration value Ta * (n−1) from the torque command value difference Td (n) and further multiplying that value by a constant K is the previous torque arbitration value Ta * (n−1). Therefore, even if the torque command value Tm * (n) of the master axis suddenly changes greatly, the torque arbitration value Ta * (n) relaxes the change, and the torque command value of the slave axis Is gradually corrected to the torque command value of the master axis. In other words, a low-frequency component is applied to the difference Td (n) between the master axis torque command value Tm * (n) and the slave axis torque command value Ts * (n) by a certain time constant. And the torque command value Ts * (n) of the slave axis is corrected. Therefore, by providing a torque arbitration unit, it is possible to prevent interference between the driving forces of the motors due to position errors, and even if the master axis torque command value changes suddenly, the slave axis torque command The influence on the value can be prevented, and stable control becomes possible.

  That is, as the arbitration torque command value Ts1 * for the slave axis, the master axis torque command value Tm *, which is a low frequency component, is used in the steady state. In the transient state, the slave shaft torque command value Ts *, which is a high frequency component, is used. That is, in the steady state, the same torque command value is obtained for the master axis and the slave axis, so that interference between the master axis motor and the slave axis motor does not occur, and stable control is possible.

Japanese Patent No. 395818 Japanese Patent No. 3537416

  In conventional tandem control using two motors, position control, speed control, and current control are performed on the master axis and the slave axis, respectively. Therefore, when axis operations such as acceleration / deceleration are performed, there is a difference in position feedback (Pm, Ps) and speed feedback (Vm, Vs) from different detectors. Differences also occur in the command values (Tm *, Ts *). In this case, interference between the master axis motor and the slave axis motor occurs, but the torque arbitration unit 35 causes the master axis torque command value Tm * and the slave axis arbitration torque command value Ts1 * to be the same in a steady state. And stable control is possible.

  However, in the steady state, the torque command value Tm * for the master axis and the arbitration torque command value Ts1 * for the slave axis are the same value, but are different from the torque command value Ts * for the slave axis. At this time, the integral component of the speed control unit 32S of the slave axis may not be the same value as the arbitration torque command value Ts1 * of the slave axis, and is not an appropriate value. At the time of stop, a large integral component is calculated by the minute velocity deviation of the slave axis in the integral component of the slave axis speed control unit 32S. For this reason, in a transient state such as a reversal operation after stopping, there is a problem that a time delay occurs until an appropriate integral component is reached, and the responsiveness of the slave shaft speed control deteriorates.

  In addition, a method to make the output of the integral component the same has been proposed, but the master axis and the slave axis do not operate exactly the same during operations such as acceleration / deceleration, so use the same integral component. As a result, the speed controllability at the time of transition decreases. Originally, the integral component differs between the master axis and the slave axis, but by using the same value, the deviation is controlled only by the proportional component. Therefore, a minute deviation occurs on either one axis or both axes.

  The present invention has been made to solve the above-described problem, and is a tandem type motor control device that drives one axis using a master axis motor and at least one slave axis motor, and the motor Each has a position control unit, a speed control unit, and a current control unit, and further calculates an arbitration torque command value for the slave axis from the torque command value for the master axis and the torque command value for the slave axis for the slave axis. A torque arbitration unit; and a command reversal detection unit that detects a reversal of a command from a host controller on the slave axis, and the command reversal detection unit detects a reversal of a command from the host controller Then, the arbitration torque command value immediately before the command reversal is set as an integral component of the speed control unit of the slave axis. Alternatively, the limit value of the integral component of the speed control unit of the slave axis is varied according to the arbitration torque command value of the slave axis.

  In the tandem motor controller that drives one axis using the master axis motor and at least one slave axis motor, the torque command value calculated for the master axis and the slave axis differs depending on the technology of the present invention. When interference occurs between the master axis motor and the slave axis motor, stable control can be performed by adjusting the torque command value of the slave axis. Also, in acceleration / deceleration operations, the torque command value calculated for the master axis and slave axis is used even when the speed controllability during transients is reduced by using the same integral component on the master axis and slave axis. By doing so, optimal control can be performed for each axis. Further, at the time of axis reversal, the arbitration torque command value immediately before the command reversal is set as an integral component of the slave axis speed control unit, or according to the slave axis arbitration torque command value, the slave axis speed control unit By changing the limit value of the integral component, the responsiveness is good and stable motor control can be performed. That is, the controllability and responsiveness of the tandem shaft can be improved not only in a steady state such as when stopped, but also in a transient state such as during acceleration / deceleration or shaft reversal.

It is a block diagram which shows the control circuit in the control apparatus of the motor which is embodiment of this invention. It is a block diagram which shows the detail of a process of the command inversion detection part in the control apparatus of the motor which is embodiment of this invention. It is a block diagram which shows the detail of the control block for performing the tandem control by the conventional two motors. It is a block diagram which shows the detail of the torque arbitration part for performing the tandem control by the conventional two motors. It is a block diagram which shows the detail of the integral component calculating part of the speed control part of the slave axis | shaft in the control apparatus of the motor concerning this invention.

  1 and 2, a first embodiment in which the present invention is applied to a motor control device based on tandem control will be described. FIG. 1 is a block diagram showing a control circuit of a motor control apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing details of the command reversal detection unit and the PI control unit of the speed control unit.

  A first embodiment in which the present invention is applied to a motor control device will be described with reference to FIG. FIG. 1 is a diagram showing a control block in the motor control apparatus of the first embodiment.

  In the master axis, a speed command value Vm * is calculated by the position control unit 1M from the position command P * and the position feedback Pm, and PI control is performed by the speed control unit 2M from the calculated speed command value Vm * and the speed feedback Vm. The torque command value Tm * is calculated by performing the above calculation. The current control unit 3M calculates a master axis current command from the torque command value Tm * and the current feedback Im, and drives and controls the master axis motor. The torque command value Tm * calculated by the speed control unit 2M is passed to the torque arbitration unit 5 through the inverter 4. Here, the inverter 4 is used to reverse the sign according to the rotation directions of the master axis motor and the slave axis motor. When the rotation directions are the same, the sign is not inverted and the rotation directions are different. In this case, the sign is inverted. Next, in the slave axis, the speed command value Vs * is calculated by the position controller 1S from the same position command value P * and position feedback Ps as in the master axis, and the calculated speed command value Vs * and speed feedback Vs are calculated. Then, the speed control unit 2S performs an operation such as PI control to calculate a torque command value Ts *. The torque arbitration unit 5 calculates an arbitration torque command value Ts1 * from the torque command value Ts * and the torque command value Tm * from the master shaft. A slave axis current command is calculated from the torque command value Ts1 * and the current feedback Is, and the slave axis motor is driven and controlled. The processing in the torque arbitration unit 5 is the same as that in the torque arbitration unit 35.

  Next, the command inversion detection unit 23 and the PI control unit of the speed control unit will be described in detail with reference to FIG. The proportional component calculation unit 21 and the integral component calculation unit 22 perform calculation with the speed error ΔV as an input, and add the values calculated by the respective calculation units to calculate the torque command value Ts * of the slave axis. The command inversion detection unit 23 outputs the torque command value Ts1 * of the immediately preceding slave axis to the integral component calculation unit 22 when detecting the inversion of the position command P *. In this case, the integral component calculation unit 22 uses the value output from the command inversion detection unit 23 as the integral component. Here, the configuration and processing contents of the PI control unit are briefly described. However, PI control that performs integral component limit processing, attenuation processing, and the like may be used.

  In the steady state, the master shaft torque command value Tm *, which is a low frequency component, is used. In the transient state, the slave shaft torque command value Ts *, which is a high frequency component, is used. That is, in the steady state, the same torque command value is obtained for the master axis and the slave axis, so that interference between the master axis motor and the slave axis motor does not occur, and stable control is possible.

  A second embodiment in which the present invention is applied to a motor control device will be described with reference to FIG. FIG. 5 is a diagram showing details of the integral component calculation unit of the speed control unit of the slave shaft in the motor control device according to the present invention.

  With reference to FIG. 5, the integral component calculation unit of the speed control unit of the slave axis will be described in detail. The limit processing unit 53 performs limit processing on the integral component calculated by adding the product of the speed error ΔV and the coefficient 51 and the previous integral component 52. In addition, the limit value of the limit processing unit 53 can be varied according to the product of the arbitration torque command value Ts1 * and the coefficient 54. Here, the coefficient 54 is assumed to vary by a value of about 1.0 to 1.3 depending on a difference in control characteristics between the master axis and the slave axis.

  Here, the influence of the integral component of the speed control unit of the slave axis on the motor control will be discussed below. The torque arbitration unit 5 uses the master axis torque command value Tm *, which is a low frequency component in a steady state, and the master axis torque command value Tm * and the slave axis arbitration torque command value Ts1 * are the same value. Stable control becomes possible. However, in a transient state such as when the shaft is reversed, the slave shaft torque command value Ts *, which is a high frequency component, is used. The slave shaft torque command value Ts * is an output of the PI control unit, and is determined by an integral component if the speed error is almost zero. Therefore, if this integral component is not an appropriate value, there is a possibility of affecting motor control. Since the speed error is almost zero at the time of axis reversal, the torque command value immediately before the command reversal can be considered to be almost the same value as the integral component. That is, by setting the torque command value immediately before the command inversion as the integral component, the integral component becomes an appropriate value in terms of control, responsiveness is good, and stable motor control can be performed.

  1M, 1S, 31M, 31S Position control unit, 2M, 2S, 32M, 32S Speed control unit, 3M, 3S, 33M, 33S Current control unit, 4,34 inverter, 5,35 Torque arbitration unit, 23 Command reversal detection Part, 21 proportional component calculation part, 22 integral component calculation part, 41, 51, 54 constant, 42, 52 previous value, 53 limit processing part.

Claims (2)

A tandem motor controller that drives one movable part using a master axis motor and at least one slave axis motor,
For each motor, a position control unit that calculates a corresponding motor speed command based on a common position command for controlling the position of the movable unit, and a corresponding motor based on the speed command calculated by the position control unit. comprising a speed control unit for calculating a torque command, a current control unit for calculating a current command of the motor corresponding based on the torque command, respectively,
Further, based on the difference between the torque command calculated by the speed control unit corresponding to the master axis motor and the torque command calculated by the speed control unit corresponding to the slave axis motor, the torque command of the slave axis is changed to the master axis. A torque arbitration unit that calculates an arbitration torque command value corrected to the torque command of
Detecting a reversal of the command from the host controller, the command reversal detection for setting said arbitration torque command value of the slave axis command immediately before the inversion in the case of detecting the inverted integral component of the speed controller of the slave axis And
A motor control device comprising: The motor control device according to claim 1,
Depending on the arbitration torque command value of the slave axis, the motor controller, characterized in that it comprises a limiting process unit for varying the limit value of the integral component of the speed controller of the slave axis.

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