JP3850381B2 - Current control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a current control device that controls a primary current of a motor.
[0002]
[Prior art]
As a conventional motor current control device, there is a control device as shown in FIG. In this device, the current deviation between the current command for each of the dq axes and the current feedback detected by the current detector D is calculated by the subtracting means SBa and SBb, and the respective current deviations are passed through the current controllers 4a and 4b to obtain the d axis. Obtain voltage command and q-axis voltage command. Each voltage command is dq converted by the coordinate converter 15a, then two-phase / three-phase conversion is performed, and the motor M is driven by the PWM inverter 17 based on the converted command. In the current feedback, the three-phase current detected by the current detector D is dq converted by the coordinate converter 15b. The coordinate converter 15b performs three-phase to two-phase conversion and dq conversion by the signal generation means 18 that generates a signal corresponding to the rotational position of the encoder E.
[0003]
Normally, the current controllers 4a and 4b in this apparatus are constituted by PI controllers. For example, as shown in FIG. 6, the current controller 4a calculates the current deviation between the current command and the current feedback by the subtracting means SBa, and multiplies the current deviation by the integral gain by the multiplier 191. An integral control system (I system) that performs integral calculation with the current integrator 193 and a proportional control system (P system) that multiplies the current deviation calculated by the subtracting means SBa by a constant. The current controller 4a further adds the outputs of the integral control system and the proportional control system by the adding means ADa, multiplies the added value by the proportional gain by the multiplying means 195, and outputs a voltage command. In this way, by configuring the current controller with PI control, not only the transient deviation of the current but also the steady deviation can be suppressed.
[0004]
[Patent Document 1]
JP-A-8-66075 [FIG. 2]
[0005]
[Problems to be solved by the invention]
Generally, the response of the control system is finite, and it takes time for the motor current to respond even if a current command is output. Although the current command is output and current begins to flow to the motor, the current integrator 193 performs integration until the motor current responds after the voltage command is output from the current controller 4a. For this reason, in the conventional current control device, the current response is delayed by the amount of accumulation of the current integrator 193, and overshoot occurs.
[0006]
On the other hand, in the control device disclosed in Japanese Patent Laid-Open No. 8-66075 [Patent Document 1], the delay of the current feedback is calculated from the change amount of the current command, the motor inductance and the motor resistance, and this delay is added to the current deviation unit. To compensate. However, differential components such as the amount of change in the current command tend to make the command response vibrate, which is not preferable for realizing smooth control. In addition, constants such as motor inductance and motor resistance are required. Furthermore, the value of motor inductance changes depending on the magnitude of current flowing through the motor, and the value of motor resistance changes with temperature. Therefore, it is necessary to compensate for the magnitude of the motor current and the motor temperature.
[0007]
An object of the present invention is to provide a current control device that can speed up the current response of a current control system without adding a motor parameter and has less overshoot.
[0008]
[Means for Solving the Problems]
The present invention relates to a current detector that detects a motor current flowing through a motor to be controlled, and a current control that outputs a voltage command based on a current deviation between a current feedback based on the motor current detected by the current detector and a current command. And a motor current control device including a motor and driving means for supplying a motor current to the motor based on a voltage command.
[0009]
In the present invention, the current controller is obtained by inputting a current control side delay compensation low-pass filter having a delay corresponding to a delay of the current control system or a transfer function, and a current command to the current control side delay compensation low-pass filter. An integral control system including a current integrator that integrates a current deviation between the current command and the current feedback, a proportional control system that outputs a command proportional to the current deviation between the current command and the current feedback, and an integral control system. And an output of the proportional control system, and a multiplying means for multiplying the output of the adding means by a current proportional gain to obtain a voltage command.
[0010]
In the proportional control system, the current deviation gain may be multiplied by the current deviation, and the calculated value being controlled in the integral control system may be multiplied by the current proportional gain.
[0011]
When the current control side delay compensation low pass filter is used as in the present invention, the current deviation between the current command having a delay corresponding to the delay of the current control system and the actually delayed current feedback is close to zero. Therefore, the accumulation amount of the current integrator can be made almost zero. As a result, overshoot can be reduced.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing an example of a specific configuration of a current controller 13 used in place of the current controller 4a or the current controller 4b of the conventional apparatus shown in FIG.
[0013]
As shown in FIG. 1, the current controller 13 of the present embodiment includes a current control-side delay compensation low-pass filter 133 having a transfer function (1 / (1 + STc)) corresponding to the delay of the current control system. Further, the current controller 13 obtains a current deviation between the delay current command obtained by inputting the current command to the current control side delay compensation low-pass filter 133 and the motor current (current feedback) by the subtracting means SB2, and integrates this current deviation. A multiplication means 131 for multiplying the gain (1 / Tvi); an integration control system including a current integrator 132 for integrating the output of the multiplication means 131; and a command proportional to the current deviation between the current command and the current feedback. And a proportional control system that outputs. The current controller 13 further includes a multiplying unit 134 that multiplies the output of the integral control system and the output of the proportional control system by the adding unit AD1 and multiplies the current proportional gain KIP and outputs it as a voltage command. The current controller 13 obtains the current deviation between the delayed current command obtained by inputting the current command to the current control side delay compensation low-pass filter 133 and the current feedback by the subtracting means SB2, and the current integral gain (1 / Tvi), a multiplication means 131 for multiplying, a current integrator 132 for integrating the output of the multiplication means 131, and a proportional control system for outputting a command proportional to the current command. Yes. The current controller 13 further includes a multiplying unit 134 that multiplies the output of the integral control system and the output of the proportional control system by the adding unit AD1 and multiplies the current proportional gain KIP and outputs it as a voltage command. In this example, the current deviation between the delay current command and the current feedback is taken by the subtracting means SB2, and the output of the current integrator 132 and the output of the proportional control system are added by the adding means AD1. The output of the adder AD1 is multiplied by the current proportional gain KIP by the multiplier 134 to obtain a voltage command.
[0014]
In the current control side delay compensation low-pass filter 133, a transfer function corresponding to the delay of the current control system is set so that the delay current command and the current feedback rise almost simultaneously, and the current integrator 132 accumulates when the current command changes. Reduce the amount. By configuring the current controller 13 in this way, it is possible to simultaneously suppress the ripple included in the current feedback and reduce the amount of accumulation in the current integrator 132 when the current command changes.
[0015]
The current control-side delay compensation low-pass filter 133 may be any transfer function that simulates the delay of the current control system, and is not limited to the transfer function of the present embodiment. Further, when the delay of the control system is large, a delay of one sample or several samples and a low-pass filter may be combined.
[0016]
FIG. 2 is a block diagram showing a modification of the current controller. When the current controller 13 'is compared with the current controller 13 of FIG. 1, the current controller 13' of FIG. 2 has a point that the multiplication means 134 'of the current proportional gain KIP is inside the proportional control system (before the addition means AD1). And the former current controller 13 is different in that the transfer function of the multiplier 131 ′ is changed in order to multiply the calculated value by the current proportional gain KIP in the integral control system. Is different. Even if it does in this way, the effect similar to the current controller 13 of FIG. 1 can be acquired.
[0017]
FIGS. 3A to 3C and FIGS. 4A to 4C are the results of simulating the current response in this control system, and are the current command, current feedback, and integrator output, respectively. All have the same current scale, and values normalized to 1 with the same current value as a reference are shown. The horizontal axis in each figure is in units of 0.001 milliseconds in time. FIG. 3 shows a case where the current control side lag compensation low-pass filter 133 is inserted, and FIG. 4 shows a simulation result when the current control side lag compensation low pass filter 133 is not inserted. In both FIG. 3 and FIG. 4, the rise of the current feedback is delayed by about 1/5 of 0.001 msec with respect to the rise of the current command. As shown in FIG. 3, when the current control side delay compensation low-pass filter 133 is inserted, the rise of the output current of the current integrator 132 is delayed to the same extent as the rise of the current feedback. The integrator output is erased by the means AD1, and the integrator output shows a small peak at the rise time of the current feedback, and is kept at a constant value close to almost zero otherwise. In this case, the height of the small peak of the integrator output is very small and is almost negligible. However, if the current control side delay compensation low-pass filter 133 is not inserted, the cancellation of the current feedback in the adding means AD1 and the output of the current integrator 132 during the rise time of the current feedback is not sufficient as shown in FIG. The peak indicated by the current integrator output at the rising point of the current feedback is higher than when the current control side delay compensation low-pass filter 133 is inserted.
[0018]
As a result, when the current control side delay compensation low-pass filter 133 is not inserted, the current overshoot becomes large. However, when the current control side delay compensation low-pass filter 133 is inserted, the current integrator 132 during motor rotation is inserted. It can be seen that the overshoot can be reduced by setting the amount of accumulation to a value close to zero.
[0019]
In addition, this invention is naturally applicable also to control of a DC motor. In that case, the dq-axis current control system and the coordinate converter as shown in the conventional example of FIG.
[0020]
【The invention's effect】
According to the present invention, since the current control side delay compensation low-pass filter is used, the current deviation between the delay current command having a delay corresponding to the delay of the current control system and the actually feedback current feedback is close to zero. The amount of accumulated current integrator can be made almost zero, and the current response can be speeded up. Therefore, by applying the current control device of the present invention, the current response can be speeded up and the overshoot can be reduced with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of a specific configuration of a current controller used in an embodiment of the present invention.
FIG. 2 is a block diagram showing an example of a specific configuration of another current controller used in the present invention.
FIGS. 3A to 3C are diagrams illustrating simulations of motor operation waveforms when a current control side delay compensation low-pass filter is inserted. FIGS.
FIGS. 4A to 4C are diagrams showing simulations of motor operation waveforms when a current control side delay compensation low-pass filter is not inserted; FIGS.
FIG. 5 is a diagram showing a configuration of a conventional motor current control device;
FIG. 6 is a diagram showing a configuration of a conventional current controller.
[Explanation of symbols]
E Encoder M Motor D Current detector 4a, 4b, 13, 13 'Current controller AD1 Adder SB1 Subtractor 131, 134, 131', 134 'Multiplier 132 Current integrator KIP Current proportional gain 133 Current control side delay compensation Low pass filter

Claims (2)

A current detector for detecting the motor current of the motor to be controlled;
A current controller that outputs a voltage command based on a current deviation between a current feedback and a current command based on the motor current detected by the current detector;
In a motor current control device comprising driving means for supplying the motor current to the motor based on the voltage command,
The current controller is
A current control side delay compensation low pass filter having a transfer function corresponding to the delay of the current control system;
An integration control system configured to include a current integrator that integrates a current deviation between a delay current command obtained by inputting the current command to the current control side delay compensation low-pass filter and the current feedback;
A proportional control system that outputs a command proportional to a current deviation between the current command and the current feedback;
Adding means for adding the output of the integral control system and the output of the proportional control system;
A motor current control apparatus comprising: multiplication means for multiplying the output of the addition means by a current proportional gain to obtain the voltage command. A current detector for detecting the motor current of the motor to be controlled;
A current controller that outputs a voltage command based on a current deviation between a current feedback and a current command based on the motor current detected by the current detector;
In a motor current control device comprising driving means for supplying the motor current to the motor based on the voltage command,
The current controller is
A current control side delay compensation low pass filter having a transfer function corresponding to the delay of the current control system;
Includes a current integrator that integrates the current deviation between the delayed current command obtained by inputting the current command to the current control side delay compensation low-pass filter and the current, and outputs the result obtained by multiplying the calculated value in the control system by a current proportional gain An integral control system to
A proportional control system that outputs a command obtained by multiplying a current deviation between the current command and the current feedback by a current proportional gain;
A motor current control device comprising an adding means for adding the output of the integral control system and the output of the proportional control system.

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