Soft starter of direct-current motor and soft starting method thereof

Abstract

The invention belongs to the technical field of motor control and power conversion, and particularly relates to a soft starter of a direct-current motor and a soft starting method thereof. The soft starter comprises a current detecting unit, a single chip microcomputer, a liquid-crystal display module, an IGBT (Insulated Gate Bipolar Transistor) driving module and an IGBT module, wherein the current detecting unit comprises a current sensor and an A / D (analog-digital) conversion module; a current signal of a main circuit is processed by the current sensor, converted by the A / D conversion module and then is transmitted into the single chip microcomputer; an output port of the single chip microcomputer is respectively connected with input ports of the liquid-crystal display module and the IGBT driving module; the output port of the IGBT driving module is connected with an input port of a motor armature (M) by the IGBT module; and the IGBT driving module is used for driving the IGBT module and realizing starting operation of the system by state switching of a starting winding. The invention has the advantages that the working under high frequency can be realized, stepless sliding and quick starting are realized, the temperature-rise influence and the power loss are less, the electromagnetic compatibility is good and the interference resistance is strong.

Description

technical field [0001] The invention belongs to the technical fields of motor control and power conversion, and in particular relates to a DC motor soft starter and a soft starting method thereof. Background technique [0002] In the backup battery pack power system widely used in the fields of electric power, chemical industry, steel, casting, plastic material processing, environmental protection, communication, etc., they are all driven by DC motors. When the DC motor is directly started, the required current is 6-8 times the rated current, which will have a large impact on the spare battery pack and other lines, which will easily cause the motor coil to be burned, the charger to be damaged, and the main circuit to be disconnected, making the equipment unable to operate. normal operation. [0003] At present, most of the DC motors are still started using the traditional method: use a DC contactor and connect a high-power resistor in series with the armature circuit of th...

AI Technical Summary

Problems solved by technology

When the DC motor is directly started, the required current is 6-8 times the rated current, which will have a large impact on the spare battery pack and other lines, which will easily cause the motor coil to be burned, the charger to be damaged, and the main circuit to be disconnected, making the equipment unable to operate. normal operation

[0003] At present, most of the DC motors are still started using the traditional method: use a DC contactor and connect a high-power resistor in series with the armature circuit of the DC motor to achieve step-down start, and limit the starting current of the motor through the resistor step-down. Or when the speed reaches a certain percentage of the rated value, the resistor is bypassed through the DC contactor. The advantage of using this method is that the control is simple and the cost is low; Reducing the starting current of the motor to twice the rated current will still cause the voltage of the DC system to drop instantaneously, which will affect the stable operation of the relay protection device; (2) DC contactors often have electric shock adhesion and Carbonization phenomenon; (3) Without protection and alarm function, it is impossible to monitor and discover potential faults in time

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