JPH01209973A - Dynamic braking device for motor - Google Patents

Abstract

PURPOSE:To reduce a cost and to improve reliability by rectifying a counter- electromotive force generated in the power line of a motor when a switching element is turned OFF, and consuming it by an energy consuming means. CONSTITUTION:A motor driver controls to drive a servo motor 34 by an inverter 33 composed of switching elements 21-26 of transistors and flywheel diodes 27-32. A DC smoothed voltage fed through a smoothing capacitor 36 is applied to the inverter 33, PWM-modulated by 3-phase AC, and applied to the motor 34. A dynamic brake device is composed of diodes 35-37, an energy consuming resistor 28, a transistor 39 and a photocoupler 44. Thus, the transistors 21-26 are turned OFF at the time of power interruption to turn OFF a DB operation signal, thereby generating a motor counter-electromotive force. This voltage is full-wave rectified to be consumed by the resistor 38 thereby to brake the motor 34, thereby stopping it.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a dynamic braking device for a motor.

(Conventional technology) Conventionally, the third type of motor dynamic braking device was
As shown in the figure, there is one constructed of relay changeover switches 1 and 2 and resistors 3 to 5. This dynamic brake 'am consists of switching elements 6 to 6 consisting of transistors.
11 and flywheel diodes 12 to 17, the motor 19 is stopped in the event of a power outage or an emergency stop, etc. in a motor drive circuit that drives and controls the motor 19 by an inverter 18 constituted by the flywheel diodes 12 to 17. Usually switch 1.
2 is switched to the a side, and the inverter 18 applies PWM modulation (pulse width modulation) to the output of the DC power supply with a three-phase AC voltage and applies it to the motor 19.

The motor 19 is used, for example, in machine tools such as robots,
In the event of a power outage or emergency stop while the machine tool is in operation, the switches 1 and 2 are switched to the b side, and the power lines A, B, and C of the motor 19 are short-circuited to each other through resistors 3 to 5. Therefore, a voltage is generated in the power aA, B, and C of the motor 19 due to the back electromotive force, which is consumed by the resistors 3 to 5.
Motor 19 stops.

(Problems to be Solved by the Invention) The conventional dynamic braking device for a motor described above uses a relay changeover switch 1.2 having contacts, so it is unreliable, expensive, requires maintenance, and is explosive. It was difficult to use it for painting robots that use gas.

(Means for Solving the Problems) The present invention provides a motor drive circuit that drives and controls a motor using a switching element, and includes a rectifier circuit and an energy consumption means connected to the rectifier circuit.

(Function) The rectifier circuit rectifies the back electromotive force generated in the motor power line when the above switching element is turned off.

The energy consuming means consumes the counter electromotive force.

(Example) FIG. 1 shows an embodiment of the invention.

This embodiment uses a switching element 2 consisting of a transistor.
1 to 26 and flywheel diodes 27 to 32 in a motor drive circuit that drives and controls the servo motor 34 with an inverter 33 configured by
This is to stop the The inverter 33 is applied with the output of an AC power source converted into DC by a converter and smoothed by a smoothing capacitor 35, which is PWM-modulated with a three-phase AC voltage and applied to the servo motor 34.

In the inverter 33, the transistors 21 to 26 are connected in series, one pair at a time, and the series circuit is connected in parallel to the DC power supply (to both ends of the capacitor 35).

A pair of transistors 21 and 22, 23 and 24゜25
and 26 are mutually turned on/off and off/on to PWM modulate the output of the DC power supply. The dynamic brake device of this embodiment includes diodes 35 to 37, an energy consumption resistor 38, a transistor 39, resistors 40, 41 . It is composed of a photocoupler 44 consisting of a light emitting diode 42 and a phototransistor 43, and the diodes 35 to 37 constitute a three-phase full-wave rectifier circuit together with the flywheel diodes 28, 30, and 32. Note that this three-phase full-wave rectifier circuit may be configured using flywheel diodes 27, 29, and 31.

During normal operation, this dynamic brake device is DB (
Dynamic brake) operation stop signal is photocoupler 4
4, the transistor 39 is turned off, resulting in a non-operating state.

In the event of a power outage or emergency, transistors 21 to 26 are turned off, the DB operation stop signal is turned off, and the servo motor 34 is turned off.
continues to rotate due to the inertia of the load 45, and a voltage is generated in the power lines A, B, and C of the servo motor 34 due to the back electromotive force of the servo motor 34. This voltage is diode 3
5-37 and flywheel diode 28, 30.32
The energy is rectified by a three-phase full-wave rectifier circuit composed of the following, and is consumed by the energy consumption resistor 38, and the servo motor 34 is stopped by applying a dynamic brake.

Further, when the load 45 attempts to be moved by hand or naturally by gravity while the servo motor 34 is stopped, a dynamic brake is applied to the servo motor 34 as in the event of a power outage or emergency.

The present invention is not limited to the above embodiments, but can be similarly applied to DC brushless motors and the like.

FIG. 2 shows another embodiment of the invention.

This embodiment is an example of a motor drive circuit that controls the drive of a DC servo motor, and the motor drive circuit includes transistors 46 to 49 and flywheel diodes 50 to 5.
It is composed of 3.

When the DC servo motor 54 is rotated in the forward direction, the transistors 46 and 49 are turned on, and a current in the forward direction is supplied from the DC power supply to the DC servo motor 54, so that the DC servo motor 54 rotates in the forward direction. When rotating in the reverse direction, the transistors 47 and 48 are turned on and a current in the reverse direction is supplied from the DC power source to the DC servo motor 54, thereby causing the DC servo motor 54 to rotate in the reverse direction.

In this embodiment, diodes 35, 36 . Energy consumption resistor 38. Transistor 39. It is composed of a photocoupler 44 consisting of resistors 40 and 41, a light emitting diode 42, and a phototransistor 43.

Diodes 35 and 36 are flywheel diodes 51
．． Together with 53, it constitutes a full wave rectifier circuit.

This embodiment operates in substantially the same manner as the above embodiment except that the power lines for the DC servo motor 54 are reduced to two.

(Effects of the Invention) As described above, according to the present invention, in a motor drive circuit that drives and controls a motor using a switching element, a rectifier circuit that rectifies the back electromotive force generated in the power line of the motor when the switching element is turned off is provided. and an energy consuming means connected to the rectifier circuit and consuming the counter electromotive force to stop the motor, and can be configured without using a switch having contacts, thereby achieving low cost, maintenance-free, and explosion-proofing. can improve reliability.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams showing each embodiment of the present invention, and FIG. 3 is a circuit diagram showing a conventional dynamic braking device for a motor. 35-37...Diode, 38...Resistor for energy consumption. Ina I ■ Rif Where? ■

Claims (1)

[Claims] A motor drive circuit that drives and controls a motor using a switching element includes a rectifier circuit that rectifies back electromotive force generated in a power line of the motor when the switching element is turned off, and a rectifier circuit that is connected to the rectifier circuit and consumes the back electromotive force. What is claimed is: 1. A dynamic braking device for a motor, comprising an energy consuming means to stop the motor.