JPS61121788A - Current control drive device of motor - Google Patents

Abstract

PURPOSE:To digitally control a current in a fast response by applying an ON signal in the prescribed period and an OFF signal by the output of a current comparator to a power drive circuit. CONSTITUTION:When a positive current command value is applied, the outputs of comparators 31, 32 become L. Then, when a signal is fed from a clock generator 43, the Q output of a flip-flop 41 becomes H. Thus, transistors 12, 13 become ON, and a positive current is flowed to a motor 20. When a detection current becomes the current command value or higher, the output of comparator 31 becomes H, the flip-flop 41 is reset, and the transistors 12, 13 are turned OFF. When the current detection value becomes the current command value or lower, the output of the flip-flop 41 again becomes H by the signal of the generator 43.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a current control drive device that controls the current flowing through a motor.

Conventional configurations and their problems In recent years, with advances in microcomputer technology, microcomputers have been widely used in motor control, and conventional analog control circuits have been replaced by digital control circuits.

A digital motor control circuit using a microcomputer has the following advantages over an analog control circuit.

(1) There is no temperature drift, gain fluctuation, or aging of the amplifier. (2) Fewer adjustments. (3) Self-diagnosis function and troubleshooting are easy. (4) Compatibility with other motor models is possible by replacing the software (ROM).

However, since microcomputers perform arithmetic processing, there is a delay in calculation time. Therefore, in a current control loop where a particularly high-speed response is required, a fast-response analog circuit is used as shown in FIG. Such a circuit cannot be said to fully take advantage of the features of a digital control circuit using a microcomputer, and has the drawbacks of an analog circuit.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the conventional art, and it is an object of the present invention to provide a current control circuit that is constructed from a simple digital circuit and has a fast response.

Structure of the Invention The present invention includes a motor drive circuit that drives the motor by turning on and off power supplied to the motor using pulse signals, a current detection circuit that detects the current flowing through the motor, and a current detection circuit that detects the detected current value and current command value. A comparator circuit that compares and outputs a signal when the detected current value is less than the current command value, and a comparison circuit that provides an on signal to the power drive circuit at a constant cycle to cause current to flow through the motor.
By comprising a pulse width control circuit that is turned off by the output of the pulse circuit, fast-response digital current control can be performed.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of the circuit configuration of the present invention. In FIG. 1, 1 is a power drive circuit, 2 is a current detection circuit, 3 is a comparison circuit, 4 is a pulse sub-control circuit, 11 to 14 are power transistors, 15 to 18 are freewheel diodes,
1 pc DC power supply, 20 DC servo motor, 31.32
is a comparator, 33 and 34 are resistors, 35 is an inverter, 36 is an exclusive NOR, 41 and 42 are D flip 70 tubes, and 43 is a clock generation circuit.

The operation will be explained below.

First, if a signal is sent from the clock generation circuit and the D input of the D flip-flop 41 is at a high level, then Q
The output becomes high level and the power transistor 12.13
is turned on, current flows, and the motor 20 rotates. A current flowing through the motor is detected by a current detection circuit 2, and is applied to a non-inverting input of a comparator 31 and compared with a current command value. If this detected current has not reached the current command value, the output of the comparator 31 is at a low level, and the output of the comparator 32 is also at a low level. Therefore, the output of the exclusive NOR 36 is at a low level, the output of the D flip-flop is maintained at a low level, and the power transistors 12 and 13 are in the on state.

Furthermore, when current flows through the motor 2Q and the detected current value exceeds the power supply command value, the output of the comparator 31 changes to high level. Then, the output of the exclusive OR 36 becomes high level, the D flip-flop is reset, the output becomes low level, the power transistors 12 and 13 are turned off, and the detected current becomes smaller and the detected current value becomes lower than the current command value. The output of the comparator 31 becomes low level again. Next, the output of the D flip-flop becomes high level again by the signal from the clock generation circuit 43, and the power transistors 12 and 13 are turned on.

Also, if the current command value becomes a negative current command value and a command is issued to flow the current in the opposite direction to the above explanation,
This time, when the output of the comparator 32 becomes high level and the signal from the clock generation circuit 43 is output, the output of the D flip-flop becomes O-level, the output of the D flip-flop 42 becomes high level, and the power transistor 12. 13 is off state, power transistors 11, 14
is turned on, a reverse voltage is applied to the motor 20, and the detected current value decreases and increases in the negative direction.

When the detected current does not reach the negative current command value, the output of the comparator 31 is high level, the output of the exclusive noor 36 is low level, and the power transistors 11 and 14 are in the on state, but the detected current value When reaches the current command value, the output of the exclusive NOR 36 becomes high level, the output of the D flip-flop 42 becomes low level, and the power transistors 11 and 14 are turned off. Then, the current flowing through the motor becomes smaller, and when the signal from the clock generation circuit 43 is output, the power transistors 11 and 14 are turned on again and the current starts flowing.

Effects of the Invention As described above, the present invention includes a power drive circuit that drives a motor, a current detection circuit that detects the current flowing through the motor, a comparison circuit that compares the detected current value with a current command value, and a current detection circuit that detects the current flowing through the motor. By configuring it with a pulse width control circuit that applies an on signal to the power drive circuit at a constant cycle to cause the current to flow, and turns it off using the output of the comparison circuit, it is possible to perform digital current control with fast response, and its practical effects are as follows. There is something big about it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a current control drive device for a motor according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional digital control device using a microcomputer. 1... Power drive device, 2... Current detection circuit, 3... Comparison circuit, 4... Pulse width control circuit.

Claims (1)

[Claims] A motor drive circuit that turns on and off power supplied to the motor using pulse signals to drive the motor, a current detection circuit that detects the current flowing through the motor, and a current value and current command value detected by the current detection circuit. a comparison circuit that outputs a signal when the detected current value becomes larger than the current command value;
A current control drive device for a motor, which includes a pulse width control circuit that applies an on signal to the motor drive circuit at a constant cycle in order to cause current to flow through the motor, and turns off the on signal using the output of the comparator.