JPH0475492A - Servo motor control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for a servo motor, and more particularly to a control device that performs digital current control using a microcomputer.

Conventional technology In recent years, motor control has required smooth and highly accurate movement, as in the control of industrial robots and NC machine tools, and at the same time, microcomputers have become faster and more sophisticated.
Current control circuits that were conventionally composed of analog circuits have been digitized, and digital current control circuits using microcomputers are now widely used.

An example of a conventional digital servo motor current control device will be described below with reference to the concave surface.

FIG. 4 is a configuration diagram of a conventional servo motor current control device. In FIG. 4, 401 is a commutation sensor that detects the rotation angle of the motor rotor, and 402 is a commutation sensor that applies a current command 1r based on the commutation signal CsO value detected by the commutation sensor 401 to the U phase of the motor armature. Current commands to phase and W phase U, ν, I
This is a distributor that distributes to r-. 403 is a current detector for detecting the current Iu flowing through the U phase of the motor armature;
04 is an A/ that converts the current IuO value into a digital value.
A D (analog/digital) converter 405 is a deviation 1du between the current command Iru to the phase of the motor armature and the feed bank current value 1fu output from the A/D converter 404.
An adder 406 calculates PI (proportional,
A compensator 407 that performs compensation calculations such as integral) control is the compensator 4.
A PWM circuit that calculates the PWM width Cu from the calculation result of 06,
408 is an inverter circuit consisting of a DC power supply Dc and six transistors.

Similar circuits are provided for the currents flowing through the (2) phase and W phase. 409 is the current 1 flowing through the ■phase of the motor armature
a current detector 410 for detecting the current 1v;
411 is an adder that calculates the deviation 1dν between the current command 1rv to the phase 1 of the motor armature and the feed bank current value 1fv, 412
413 is a compensator that performs compensation calculations such as PI (proportional, integral) control on the deviation 1 dv, and 413 is PW from the calculation result of the compensator 412.
This is a PWM circuit that calculates M width Cv. 414 is a current detector for detecting the current 1- flowing through the W phase of the motor armature, 415 is an A/D converter that converts the value of the current 1W into a digital value, and 416 is a current detector for detecting the current 1- flowing through the W phase of the motor armature. Deviation Idw between current command 1r- and feedback current value If-
417 is a compensator that performs compensation calculations such as PI (proportional, integral) control on the deviation rc1m, and 418 is a PWM circuit that calculates the PWM width Cw from the calculation result of the compensator 417. 419 is a three-phase motor, and 420 is an armature.

The operation of the motor current control device configured as described above will be described below.

FIG. 5 shows the processing contents of the current control calculation. Step Sl
The current command IrO value to be applied to the three-phase synchronous motor 419 is obtained at regular intervals at l. In step S12, based on the commutation signal CsO value detected by the commutation sensor 401, the distributor 402 distributes the current command Ir to each current command 1 ruSI rvIrw to the U phase, ■ phase, and W phase of the motor armature. do. In step S13, it is determined whether or not the current Tu flowing through the U phase of the motor armature is to be controlled. If the control calculation is for the current 1u flowing through the U phase, the current detector 403 detects I
u is detected, and in step S15, the A/D converter 404 converts the value of the current 1u into a feedback current value 1fu, and in step 316, the adder 405 converts the current command Iru to the U phase of the motor armature and the feedback current. [1
The deviation Idu of fu is determined, and in step S17 the compensator 40
6, the deviation 1du is subjected to compensation calculation such as PI (proportional, integral) control, and the PWM width Co is determined from the calculation result by the PWM circuit 407. In step 518, the PWM width Cu is
is output to the inverter circuit 408.

If no in step S13, the process moves to step S19, and it is determined whether or not the current Iv flowing through the phase 2 of the motor armature is to be controlled. If the calculation is to control the current flowing through the phase ■■, the current detector 403 detects Iv in step S20, and the A/D converter 410 converts the current IvO value into a feedback current value Ifν in step S21. ,
In step S22, the adder 411 calculates the V of the motor armature.
The deviation rdv between the current command 1rv to the phase and the feedback current value 1fv is calculated, and in step S23, the compensator 412 performs compensation calculations such as P[(proportional, integral) @ control on the deviation rdv, and the PWM circuit 413 calculates the calculation result. From PW
Find the M width Cv, and in step S24 P W M IM
Cv is output to the inverter circuit 408.

If no in step S19, the process moves to step S25, where the current detector 414 detects the current Iw flowing through the W phase, and in step 326, the A/D converter 415 converts the value of the current 1w into a feedback current value. In step S27, the adder 416 calculates the deviation 1d- between the current command 1rw to the W phase of the motor armature and the feedback current value If-, and in step 82B, the compensator 417 converts the deviation 1d- into PI( Compensation calculations such as proportional and integral) control are performed, and the PWM circuit 418 performs PWM control from the calculation results.
@C- is determined, and PWMII@C- is output to the inverter circuit 408 in step S29.

Then, the above steps S18, 324 and S29 are transferred to the step S30, and the inverter [1lJIl
408(7) Transistor switch ON, OFF
As a result, the armature 4 of the three-phase synchronous motor 419
A current flows through 20.

Problems to be Solved by the Invention However, in the above configuration, in order to perform control calculations on the armature current of the motor, a calculation circuit must be provided for each phase of the U phase, ■ phase, and W phase. First, there is a problem in that it requires a complicated circuit configuration and a large number of memory elements.

Further, a large number of current detectors are required to detect the current flowing through each phase of the U phase, ■ phase, and W phase. Current detectors have problems in that they are expensive and require a large installation space.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a servo motor control device that allows current to flow according to a command value without using a complicated arithmetic circuit or a large number of current detectors.

Means for Solving the Problems In order to solve the above-mentioned problems, a motor current control device according to the present invention includes an inverter circuit that is made up of a motor, a power source, and a switching element and that flows current through the motor; A current detector detects a composite current flowing through the inverter circuit, a commutation sensor detects the rotation angle of the rotor of the motor, and a commutation sensor detects the deviation between the current command value and the current feedback value that is the output of the current detector. It consists of an adder to obtain the output, and a PWM circuit to generate a PWM signal to be input to the inverter circuit and a switching pattern of the switching element based on the output of the adder and the output of the commutation sensor.

According to the above-described configuration, the present invention detects the value of the composite current flowing through the inverter circuit, determines the deviation from the current command value, and controls the inverter circuit on/off based on this deviation and the output of the commutation sensor. This controls the armature current of the motor to flow in accordance with the command value.

EXAMPLE Hereinafter, a servo motor control device according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a servo motor current control device. In the first session, 1 is a current detector, 2 is an A/D
(analog/digital) converter, 3 is an adder, 4 is a compensator, 5 is a commutation sensor, 6 calculates the PWM width and the switching pattern of the inverter circuit from the output of the compensator 4 and the output of the commutation sensor 5. P.W.
M circuit, 7 is an inverter circuit consisting of a DC power source Dc and six transistors, and 8 is a three-phase synchronous motor.

The current detector 1 detects not the current flowing through each phase of the armature of the motor 8, but the combined current Is flowing through the inverter circuit 7. The A/D converter 2 converts the value of the current Is into a digital value and outputs it to the adder 3 as a feedback current If. Adder 3 calculates deviation Id between current command 1r and feedback current If. Compensator 4 has P for deviation 1d.
Performs compensation calculations such as I (proportional, integral) control. The commutation sensor 5 detects the rotation angle of the rotor of the motor 8 and outputs the commutation signal Cs to the PMW circuit 6. The PWM circuit 6 calculates PWM widths Cu, C for each phase based on the deviation 1d after compensation calculation and the commutation signal Cs.
ν, C- and the switching pattern of the switching element are output to the inverter circuit 7.

Next, the operation of the motor current control device configured as above will be explained with reference to FIG. 2.

First, in step S1, a current command IrO value to be applied to the three-phase synchronous motor 8 is obtained at regular intervals.

Next, in step S2, the current detector 1 detects the composite current Is of the inverter circuit 7, in which the sum of the currents flowing through the U-phase, ■-phase, and W-phase flows, and in step S3, the value of this composite current Is is set to A. /D (analog/digital) converter 2
is digitized and converted into a feedback current value If.

Next, in step S4, the adder 3 calculates the deviation Id between the current command 1r to be passed to the motor armature and the feedback current value If. Next, in step S5, the compensator 4 performs compensation calculations such as PI (proportional, integral) control on the deviation 1d,
The Saraotoko PWM circuit 6 calculates the PWM of each phase from the calculation results.
In addition to determining the widths Cu, Cv, and C-, the commutation signal C detected by the commutation sensor 5 is
s, inverter circuit 7 as shown in the graph shown in FIG.
determine the switching pattern of

The graph shown in FIG. 3 will be explained in detail.

The rotor of the motor (not shown) is 60 degrees from the reference position.
Until it rotates, the upper switch tJ of the U phase among the six transistor switches of the inverter circuit 7 and
The lower phase switch VL is turned on. In this state, current flows from the DC power source Dc of the inverter circuit 7 in Fig. 1 through the U phase and ■ phase of the armature of the three-phase synchronous motor via the upper switch UM of the U phase. , ■ flows to ground through the lower switch ■ of the phase. Below, when the motor rotor is between 60 degrees and 120 degrees,
The upper switch U of the phase and the lower switch WL of the W phase are turned on. When the rotor of the motor is between 120 degrees and 180 degrees, the upper switch ■H of the ■ phase and the lower switch W of the W phase are turned on. rotor from 180 degrees to 24
When it is between 0 degrees, the upper switching of the ■ phase and the U
The lower switch U of the phase is turned on. When the rotor is between 240 degrees and 300 degrees, the upper switch WH of the W phase and the lower switch UL of the U phase are turned on. Furthermore, when the rotor is between 300 degrees and 360 degrees, the upper switch WM of the W phase and the lower switch (2) of the (2) phase are turned on. In this way, two of the six transistor switches of the inverter circuit 7, one on the upper side and one on the lower side, are always turned on, so that current flows through the armature of the three-phase synchronous motor.

The explanation of FIG. 2 will be continued. In step S6, the PWM widths Cu, Cv, C- obtained in step S5 and the switching pattern of the inverter circuit are output to the inverter circuit 7.

As a result, as described above, current flows through the armature of the three-phase synchronous motor.

As described above, according to the present embodiment, the control calculation of the armature current of the motor is performed by detecting the value rS of the composite current flowing through the inverter circuit 7 using only one current detector 1, and calculating the control calculation for the armature current of the motor by detecting the value rS of the composite current flowing through the inverter circuit 7 and comparing it with the current command Ir. By controlling the inverter circuit 7 on and off based on the deviation 1d and the commutation signal Cs, and controlling the motor armature current to flow according to the command value, the current control calculation circuit can be simplified. In addition, the number of current detectors is only one. Although this embodiment has been described using a three-phase synchronous motor as an example, the present invention can also be applied to a DC motor. Furthermore, it is also possible to use a resistor as a current detector.

Effects of the Invention As described above, the servo motor control device of the present invention uses only one current detector to detect the value of the composite current flowing through the inverter circuit, and also detects the deviation from the current command and the commutation signal. Since the inverter circuit is controlled on and off to control the motor armature current, the current control calculation circuit can be simplified and the number of current detectors can be reduced to just one. , it has the effect of being compact and can be constructed at low cost.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a servo motor control device according to an embodiment of the present invention, Fig. 2 is a flowchart of the current control calculation, and Fig. 3 is the relationship between the rotation angle of the motor rotor and the switching pattern of the inverter circuit. FIG. 4 is a block diagram of a conventional servo motor control device, and FIG. 5 is a flowchart of the current control calculation. Current detector A/D converter - Adder - Commutation sensor PWM circuit Inverter circuit - Three-phase synchronous motor.

Claims (1)

[Claims] (1) An inverter circuit consisting of a motor, a power supply, and a switching element that flows current through the motor, one current detector that detects a composite current flowing through the inverter circuit, and detects the rotation angle of the rotor of the motor. a commutation sensor that calculates a deviation between a current command value and a current feedback value that is the output of the current detector; and a PWM signal that is input to the inverter circuit based on the deviation and the output of the commutation sensor. A servo motor control device comprising a switching pattern of switching elements and a PWM circuit that creates a switching pattern.