JPH09271189A - Control equipment of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control equipment of a motor which can optimize the rotation and the stop of a motor while controlling the rotation of the motor. SOLUTION: This control equipment is provided with a rotation detecting means 102 of a motor 103, a rotation control means 101 outputting a torque command signal for applying feedback to minimize the error from a target value, a current detector 206, an error amplifier 201 and its output stage 202. A current control circuit 104 applies a current proportional to the torque command signal by control. An offset correcting means corrects the offset of the torque command signal, by adjusting the output level of the torque command signal, in such a manner that the output signal of the error amplifier 201 when a current does not flow in the motor 103 becomes equal to the specific target value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device.

[0002]

2. Description of the Related Art FIG. 7 shows a block diagram of motor control as a conventional example. In FIG. 7, 501 is a rotation control means, 502 is a rotation detection means, 503 is a motor, 504.
Is a current control circuit. In FIG. 7, a position detection signal corresponding to the rotation angle position of the motor 503 is taken out and passed through the rotation detecting means 502 to obtain position data. As the rotation detecting means, there are one using an optical encoder and one using an MR element to take out two-phase signals and convert them into digital values. The rotation control means 501 detects the rotation position of the motor 503 detected by the rotation detection means 502 and the rotation control means 5.
The difference from the target position defined inside 01, that is, the position error is calculated, and the speed error is calculated by differentiating the position error and the calculation is performed to output the torque command signal and the rotation direction command to control the current. Input to the circuit 504.

FIG. 8 is a detailed block diagram of the current control circuit 504 shown in FIG. In FIG. 8, an error amplifier 601 is composed of resistors R7 to R9 and an operational amplifier A2. Reference numeral 602 denotes an output stage, and the error amplifier 60
The motor 503 is driven according to the 1 output signal. 604
Is a microcomputer and takes in position data from the rotation detecting means 502. A D / A converter 605 converts a digital value from the microcomputer into an analog value and outputs it as a torque command signal. R12 is a current detection resistor and constitutes a current detector 606 together with the resistors R10 and R11. The current detector 606 detects the current flowing through the motor 503 and inputs the detected current value to the error amplifier 601.
The error amplifier 601 calculates the difference between the detected current value detected by the current detector 606 and the torque command signal by a predetermined gain (-R9 /
R7) Amplified and output to the output stage 602. Output stage 60
2 amplifies the input voltage by electric power and supplies a current to the motor 503. With such a configuration, a current proportional to the torque command signal is controlled to flow in the motor 503.

With the above configuration, the motor control is performed so as to rotate or stop the motor 503. An example of the rotation detecting means applied to the motor control device is described in Japanese Patent Application No. 8-201621. FIG. 9 is a control block diagram showing how the rotation control of the motor is performed. The rotation control will be described below with reference to FIG. 9. In FIG. 9, reference numerals 701 and 302 denote means for adding / subtracting signals, 303 denotes means for adding signals, 30
Reference numeral 4 is a differentiating means, and 305 and 306 are gain multiplying means.

The rotation angle position of the motor 503 is detected by the rotation detection means 502, and the position data is detected by the rotation control means 5.
01 to the microcomputer 604 inside. Microcomputer 60
4 performs the following processing. A means 302 for adding / subtracting the target position determined in advance and the position data detected by the position detecting means 502 performs addition / subtraction, a position error is calculated, and a gain is multiplied by a means 306 for multiplying the position error by gain. At the same time, it is passed through a means 304 for differentiating the position error. Differentiating the target position and the position data gives the target speed and the speed data, so that the speed error can be calculated by differentiating the position error. The velocity error is output through the gain multiplication means 305. The means 303 for adding these two output values performs addition, and the output value is output to the current control circuit 504 as a torque command signal by the D / A converter 605. This torque command signal forms a feedback loop in the order of the current control circuit 504, the motor 503, the rotation detection means 502, and the rotation control means 501 as shown in FIG. 7, so that the position error and the speed error are minimized. Is output as a torque command signal for feedback. The reason why the speed error is calculated and added with the position error is to stabilize the feedback loop gain by simultaneously performing the speed control and the position control. Also, means 3 for gain multiplication
If the gain value of 06 is set to 0, motor control can be performed only by speed control. Means 70 for adding and subtracting this torque command signal and the current detection value detected by the current detector 606
The error voltage is obtained from 1, and the rotation control of the motor 503 is performed.

FIG. 10A shows the relationship between the position error and the torque command signal. There is a proportional relationship between the position error and the torque command signal, and when the target position is reached, the position error becomes 0, so the rotation control means 501 outputs a reference value inside the rotation control means, that is, a reference torque command signal. . Next, FIG.
0 (2) shows the relationship between the torque command signal and the motor current. Ideally, there is a proportional relationship between the torque command signal and the motor current, and when the torque command signal is the reference torque command signal, the motor current is 0. From these two relationships, as shown in FIG. 10 (3), when there is no offset between the position error and the motor current, there is a proportional relationship, and when the position error is 0, the motor current becomes 0. When the position error is more positive than 0, the rotation control means 501 outputs a positive rotation direction command to the output stage 602 and the motor 503.
Is rotated in the forward direction. When the position error is more negative than 0, the rotation control means 501 outputs a negative rotation direction command to the output stage to rotate the motor 503 in the reverse direction.

Due to this relationship, when the rotation control is performed, the motor current becomes 0 when the target position is reached, so that the movement to the target position and the stop operation can be performed.

[0008]

However, in the above structure, the rotation control of the motor 503 may become unstable. That is, when the rotation control of the motor 503 is performed, when the motor 503 reaches the target position, the rotation control unit 501 outputs the reference torque command signal.
However, current may actually flow in the motor 503 even though the reference torque command signal is output. That is, the torque command signal output from the rotation control unit 501 may have an offset.

First, as shown in FIG. 10A, an offset ΔV1 may occur between the position error and the torque command signal. That is, D inside the rotation control means 501
When the offset is generated in the A / A converter 605 and the position error is 0, there is a deviation between the torque command signal output inside the microcomputer 604 and the torque command signal actually output. is there.

Next, as shown in FIG. 10 (2), an offset ΔV2 may occur in the relationship between the torque command signal and the motor current. This is due to the influence of the input bias current of the error amplifier 601 and the variation of the current detection value due to the variation of the resistance values of the resistors R10 and R11.
This is the case where the error voltage is output to 01 and the motor current does not become 0.

Due to the influence of these two offsets, the relationship between the motor current and the position error is that when an offset -ΔV3 appears as shown in FIG. 10 (3), a region where the motor current does not flow, that is, a so-called dead zone occurs. If you move or stop to the target position, you cannot move or stop to the correct position. On the other hand, when the offset ΔV3 shown in FIG. 10 (3) has occurred, when the movement or stop operation is performed to the target position, the current continues to flow to the motor 503 at the target position, and the motor 503 repeats forward rotation and reverse rotation. Therefore, there is a problem that the vibration of the motor 503 becomes large and the power efficiency becomes poor.

The above problems also occur when the motor control is performed only by the speed control as described above. Therefore, it is necessary to adjust the offset of the torque command signal so that the motor current becomes zero when the position error or the speed error is zero. Therefore, an object of the present invention is to provide a motor control device that can control the rotation of the motor while keeping the rotation and stop of the motor in an optimum state.

[0013]

According to a first aspect of the present invention, there is provided a motor control device including a rotation detecting means for detecting the position or speed of the motor, and a position or speed of the motor detected by the rotation detecting means and a target position or target. Rotation control means for detecting a difference from the speed and outputting a torque command signal for feedback so that the position error or the speed error is minimized, and a current detector for detecting a current flowing through the motor, It has an error amplifier that amplifies the error by comparing the detected current signal detected from this current detector with the torque command signal, and has an output stage that power-amplifies the output signal of this error amplifier and supplies a current to the motor. Then, the output signal of the error amplifier when the current is not flowing to the motor and the current control circuit that controls the current to flow to the motor in proportion to the torque command signal reaches the predetermined target value. By adjusting the output level of the torque command signal such that properly, but with an offset correcting means for correcting the offset of the torque command signal.

According to the motor control device of the first aspect, the output level of the torque command signal is adjusted so that the output signal of the error amplifier when the current does not flow in the motor becomes equal to a predetermined target value. Since the offset of the torque command signal is corrected by this, it is possible to automatically and highly accurately adjust the offset of the torque command signal.Therefore, the rotation and stop of the motor can be optimized while controlling the rotation of the motor. You can

According to a second aspect of the present invention, in the motor control apparatus according to the first aspect, the offset correction means detects a difference between the output signal of the error amplifier and a predetermined target value, and the detected target error is minimized. The feedback control loop adjusts the output level of the torque command signal by performing the feedback control as described above. The motor control device according to the second aspect has the same effect as the first aspect.

According to a third aspect of the present invention, there is provided a motor control device according to the first or second aspect, wherein the offset correction means is
Detects the difference between the output signal of the error amplifier and the predetermined target value,
It has means for integrating the target error so that the detected target error is minimized. According to the motor control device of the third aspect, in addition to the effect of the first aspect or the second aspect, the steady error of the target error can be reduced to 0 by including the integrating means.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the overall configuration of a motor control device according to the present invention. In FIG. 1, 101 is rotation control means, 102 is rotation detection means, 103 is a motor, and 104 is a current control circuit.

In FIG. 1, position data is obtained by extracting a detection signal corresponding to the rotational angle position of the motor from the motor 103 with an encoder or the like and passing it through the rotation detecting means 102. As the rotation detecting means 102, there are one that uses an optical encoder, one that uses an MR element to take out two-phase signals and convert them into digital values. Rotation control means 101
Is a difference between the position of the motor 103 detected by the rotation detection means 102 and the target position, that is, a position error is calculated, and a calculation is performed to output a torque command signal and a rotation direction command, which are input to the current control circuit 104. To do.

Referring to FIG. 2, the internal configuration of the current control circuit 104 will be described. 201 is an error amplifier and a resistor R
1 to R3 and an operational amplifier A1. 202
Is an output stage, and drives the motor 103 according to the output signal of the error amplifier 201. R6 is a current detection resistor,
A current detector 206 is configured with the resistors R4 and R5.
The current detector 206 detects the current flowing in the motor 103 and inputs it to the error amplifier 201.

In FIG. 2, the current detector 206 detects the current flowing in the motor 103, and the error amplifier 201
Is a predetermined gain (-
It is amplified by (R3 / R1) times and output to the output stage 202. The output stage 202 power-amplifies the input voltage, and the motor 103
Apply current to With such a configuration, the rotation control means 10
The motor 103 is controlled so that a current proportional to the torque command signal output from 1 flows to the motor 103.

Next, the offset of the torque command signal is corrected by adjusting the output level of the torque command signal so that the output signal of the error amplifier 201 when the current does not flow in the motor 103 reaches a predetermined target value. To do. Hereinafter, a configuration including the offset correcting means of the present invention and an operation of offset correcting the torque command signal will be described. FIG.
In the figure, 203 is an A / D converter, 204 is a microcomputer, and 205 is a D / A converter.

First, the microcomputer 204 outputs a current interruption command to the output stage 202. Output stage 202 from current cutoff command
Shuts off the current flowing through the motor 103. Since the motor current does not flow through the current detection resistor R6 by outputting the current cutoff command, a constant value (Vcc × R5 / (R4 + R5)) is input to the positive input terminal of the operational amplifier A1 as a current detection value.
Is entered. As a result, the output signal of the error amplifier 201 is determined by the torque command signal output from the rotation control means 101 without being affected by the motor current. Further, the microcomputer 204 outputs an internally determined voltage reference value as a reference torque command signal from the D / A converter 205 and inputs it to the negative input terminal of the operational amplifier A1. The error amplifier 201 compares the detected current value with the reference torque command, multiplies the difference by (-R3 / R1), and outputs the result. Here, the circuit is designed so that the detected current value when the current does not flow in the motor 103 and the output signal of the reference torque command signal output through the D / A converter 205 are equal, but the offset of the D / A converter 205 is set. They are not equal due to variations and offsets due to variations in resistance values of the resistors R4 and R5 of the current detector 206. Therefore, the output obtained by amplifying this difference, that is, the output voltage of the error amplifier 201 is taken into the A / D converter 203 as an error voltage, the offset correction process is performed by the microcomputer 204, and the offset correction is performed by the D / A converter 205. By outputting the information of the torque command signal to the D / A converter 205, the torque command signal is corrected and the output signal of the error amplifier 201 is controlled to be the target value. The output voltage of the error amplifier 201 is (-R3 /
Since it is amplified R1) times, if the ratio of R3 / R1 is increased, the error voltage can be accurately captured by the A / D converter 203 even if the offset amount is small, and the resolution is slightly low (for example, 8 Offset can be detected even with an A / D converter.

FIG. 3 is a control block diagram showing how the rotation control of the motor 103 and the offset correction process are performed.
The means for controlling the rotation of the motor 103 is the same as in the conventional example. In FIG. 3, 301 and 302 are means for adding and subtracting signals, 303 is means for adding signals, 304 is means for differentiating, 305 and 306 are means for multiplying gain,
Reference numeral 307 is a means for adding / subtracting signals, 308 is a means for multiplying a gain, 309 is a means for integrating, and 310 is a means for adding.

The process of performing the offset correction process of the torque command signal by performing the feedback control will be described below with reference to FIG. The output signal of the error amplifier 201 is input to the A / D converter 203 inside the rotation control means 101, and then to the microcomputer 204. The microcomputer 204 inside the rotation control means 101 performs the following processing. The target value determined in advance in the microcomputer 204 and the output signal of the error amplifier 201 are input to the A / D converter 2
Means 30 for adding / subtracting A / D converted data from 03
Add / subtract by 7. This output value, that is, the target error is passed through a means 308 for multiplying the gain. At the same time, it is passed through a means 309 for integrating. These two output values and the motor 103
The output value of the adding means 303 that has passed through the means for controlling the rotation is added by the adding means 310. The D / A converter 205 outputs the output value of the adding means 310 as a torque command signal, and the adding / subtracting means 301 performs addition / subtraction with the current detection value of the current detector 206, and the error amplifier 20
Output to 1. However, when performing the offset correction process, the motor current does not flow due to the current interruption command, and the process of performing the rotation control is not executed.

The error amplifier 201, the A / D converter 203, the addition / subtraction means 307, the gain multiplication means 308, the integration means 309, and the addition means 31 described above.
0, D / A converter 205, and addition means 301 are a feedback control loop for performing offset correction.
By executing such a feedback control loop for a predetermined time (for example, 100 msec), the target error with respect to the target value reaches a predetermined time T from the offset correction start t1 to the offset correction end t2 as shown in FIG. Converges to 0. This means 30 for integrating the target error
This is because the effect of the low-pass compensation filter can be obtained by passing the value through 9, and the steady-state deviation of the target error with respect to the target value can be made zero.

The output value of the D / A converter 205 at this time is a value at which the output current of the current control circuit 104 becomes 0, which means that the offset correction value is obtained. FIG.
6 is a flowchart showing how the present invention performs offset correction processing. The code for each step is shown in parentheses below. First, the power is turned on (401), and initial settings such as I / O port, interrupt setting, output port, memory initial value setting, and peripheral hardware resetting (4
02), the current cutoff command (403) and the reference torque command signal output (404) are output. Here, it is determined whether the processing has been performed for a predetermined time (405). If the predetermined time has not elapsed, the A / D conversion process (407) is performed, and the error between the target value and the A / D converted value of the error voltage is calculated (408). The value that has passed through the means for calculating the error (408) is subjected to gain multiplication (409), integration processing (410), and addition processing (411) together with the gain multiplied (409) value. This added value is D / A output processed (41
2) is performed, and a determination process of whether the process has been performed for a predetermined time (405) is performed.

As described above, the offset correction process is performed in the feedback control loop until the predetermined time has elapsed. The predetermined time for performing the offset correction processing is determined from the time when the offset correction processing is actually performed and the offset correction can be accurately performed. If you perform processing for a predetermined time,
The offset correction process is terminated, that is, the offset correction value is fixed, the current interruption command is canceled (406),
The process shifts to a loop for performing the rotation control process (413).

By performing such processing, the component for correcting the offset is added to the torque command signal, and the motor 1
The rotation control of 03 can be made into the optimal state. It should be noted that this process is automatically executed by the microcomputer 204 after the power is turned on. According to this embodiment, since the offset adjustment of the torque command signal can be automatically and highly accurately performed, the rotation and stop of the motor 103 can be optimized while controlling the rotation of the motor 103. .

In particular, the offset correction means has a means for detecting the difference between the output signal of the error amplifier and a predetermined target value and integrating the target error so that the detected target error is minimized. The steady-state deviation of can be zero. FIG. 6 shows another embodiment of the processing for correcting the torque command signal by the microcomputer 204, and is a flow chart for explaining the motor position control method. First, power is turned on, initial settings such as input / output port, interrupt setting, output port, memory initial value setting, and peripheral hardware resetting are performed, and then a current cutoff command is output to flow to the motor 103. The current is cut off and the motor 103 is stopped. In this state, the reference torque command signal is output, the output signal of the error amplifier 201 is taken in by the A / D converter 203, and after being converted into a digital value,
Error information is calculated by comparing with a predetermined voltage reference value inside the microcomputer 204. If the error information is not 0, the error information is passed through a phase compensation filter, multiplied by a predetermined gain, and added to a predetermined voltage reference value inside the microcomputer 204, and the D / A converter 205 outputs a reference torque command signal. Output as. Again, A
The / D converter 203 takes in the output signal of the error amplifier 201 and calculates error information in the same manner as described above. This series of processing loops is repeated until the error information converges to 0 to determine the offset value.

When the position control is performed after this processing is performed, the component for correcting the offset is added to the torque command signal, and the position control of the motor 103 can be set to the optimum state. It should be noted that such processing is automatically executed by the microcomputer 204 after the power is turned on. In the present invention, the correction means of the rotation control means outputs a current cutoff command to the output stage when correcting the offset of the torque command signal, and the output stage cuts off the current flowing to the motor by the current cutoff command. By shutting off the current flowing to the motor and stopping the motor in response to the current shutoff command, it is possible to eliminate the change in the output signal of the error amplifier due to the change in the current flowing to the motor and to stabilize the output signal. Therefore, by taking the output signal of the error amplifier into the rotation control means, calculating the offset value from the error signal, and adding the offset correction component to the torque command signal, the offset of the torque command signal can be corrected, Optimal position control can be performed.

The correction means of the rotation control means detects the output signal of the error amplifier and performs feedback control so that the detection value of the error amplifier becomes a predetermined value, and takes in the output signal of the error amplifier A. A / D converter and a current cutoff command are output to the output stage when the offset of the torque command signal is corrected, and the current flowing to the motor is cut off to the output stage according to the current cutoff command.
A microcomputer for inputting the output signal of the D converter, applying a predetermined gain to this, and adding an offset value to be corrected to the torque command signal, and a D / A for D / A converting the output of this microcomputer and inputting it to the error amplifier. With the configuration including the converter, the same effect as described above can be obtained.

As a motor rotation control method, a process of outputting a current cutoff command from the rotation control means to the output stage of the motor to cut off the motor current, and a reference torque command signal from the position control means when the motor is stopped. To output the error amplifier output signal and compare it with a predetermined reference value to calculate error information; to determine whether this error information is 0; With a configuration including a step of adding an offset value corresponding to error information to the reference torque command signal and a step of determining an offset value and performing position control processing when the error information is 0, the same effect as described above can be obtained. is there.

[0033]

According to the motor control device of the first aspect, the output level of the torque command signal is adjusted so that the output signal of the error amplifier when the current is not flowing through the motor becomes equal to a predetermined target value. By doing so, the offset of the torque command signal is corrected, so that the offset adjustment of the torque command signal can be performed automatically and with high precision, so that the rotation and stop of the motor can be optimized while controlling the rotation of the motor. can do.

According to the motor control device of the second aspect, the same effect as the first aspect can be obtained. According to the motor control device of the third aspect, in addition to the effect of the first aspect or the second aspect, the steady error of the target error can be reduced to 0 by including the integrating means.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a detailed block diagram thereof.

FIG. 3 is a control block diagram for performing offset correction processing.

FIG. 4 is a flowchart for performing offset correction processing of the rotation control means.

FIG. 5 is an explanatory diagram illustrating a state in which a target error converges to a target value when offset correction is performed.

FIG. 6 is a flowchart of another embodiment for performing offset correction processing of the rotation control means.

FIG. 7 is a block diagram of a conventional example.

FIG. 8 is a detailed block diagram thereof.

FIG. 9 is a control block diagram for performing rotation control.

FIG. 10 is a diagram for explaining offset, (1) is a relationship diagram between position error and torque command, (2) is a relationship diagram between motor current and torque command, and (3) is a relationship between position error and motor current. It is a figure.

[Explanation of symbols]

 101 rotation control means 102 rotation detection means 103 motor 104 current control circuit 201 error amplifier 202 output stage 203 A / D converter 204 microcomputer 205 D / A converter 206 current detector 309 means for integrating

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Claims (3)

[Claims] 1. A rotation detecting means for detecting a position or speed of a motor, and a difference between the position or speed of the motor detected by the rotation detecting means and a target position or target speed to detect a position error or a speed error. A rotation control means for outputting a torque command signal for applying feedback so as to minimize, and a current detector for detecting a current flowing through the motor,
An output stage that has an error amplifier that amplifies the error by comparing the detected current signal detected from the current detector with the torque command signal, and an output stage that power-amplifies the output signal of the error amplifier and sends a current to the motor. A current control circuit having a current control circuit for controlling a current proportional to the torque command signal to flow in the motor, and an output signal of the error amplifier when no current flows in the motor becomes equal to a predetermined target value. A motor control device comprising: an offset correction means for correcting the offset of the torque command signal by adjusting the output level of the torque command signal. 2. The offset correction means detects a difference between an output signal of the error amplifier and a predetermined target value, and feedback control is performed so that the detected target error is minimized to thereby output the output level of the torque command signal. The motor control device according to claim 1, further comprising a feedback control loop that adjusts. 3. The offset correcting means has means for detecting a difference between an output signal of the error amplifier and a predetermined target value, and integrating the target error so that the detected target error is minimized. Alternatively, the motor control device according to claim 2.