Low-voltage and high-voltage motor soft starter composed of three-phase commutation bridge

Abstract

The invention relates to a soft starter of low-voltage motor and high-voltage motor consisting of a three-phase rectifying bridge and relating to the non-impact current starting and speed control of an AC motor, wherein a motor stator three-phase winding is connected with the AC side of a three-phase fully-controlled rectifying bridge, while the DC side of the rectifying bridge is communicated by a conducting wire, thereby forming a low-voltage soft starter; the low-voltage AC exciting coil of a three-phase saturable reactor is connected with the AC side of the three-phase fully-controlled rectifying bridge, while the DC side of the rectifying bridge is communicated by a conducting wire and a high-voltage motor stator three-phase winding is connected in series with the high-voltage coil of the saturable reactor, thereby forming a high-voltage motor soft starter. The high voltage / low voltage soft starter has a full-voltage electromagnetic switch capable of charged attracting when a motor starts; when starting is finished, the electromagnetic switch is capable of powerdown release to ensure full-voltage operation of the motor; moreover, when adopting the 'one-drive-N' proposal, the soft starter needs to be equipped with N motor circuit breakers but omits N+1 electromagnetic switches as compared with the prior soft starter.

Description

(1) Technical field [0001] The invention mainly relates to the non-impact current starting of a 380v / 3-6-10kv AC motor and the application of a controllable rectifier circuit and an AC voltage regulating circuit in a thyristor grid commutation circuit. (2) Background technology [0002] The AC squirrel-cage induction motor has a simple and compact structure, is sturdy and durable, has high efficiency when converting electrical energy into mechanical energy, is easy to maintain, and has a large number of applications. However, since the current reaches 5-7 times the rated current when starting, it will cause impact on the load, loss of electric energy and drop of grid voltage...and also affect other users. Since the advent of SCR solid-state soft starters in the 1980s, they have satisfactorily solved the starting problems of AC motors. At that time, European Power Semiconductor Co., Ltd. was the first to produce "lectron" SCR solid-state soft starters in the world, and then ...

AI Technical Summary

Problems solved by technology

For example, the high-voltage asynchronous motors in the drive system of fans and water pumps (compressors, oil, gas) in traditional industries in my country often cause a sharp drop in grid voltage due to too much starting current, which affects the normal operation of other process equipment, so they must not be used. Unrestricted "shutdown" to avoid the same impact caused by restarting, which will cause the system to "vent and return" and waste electric energy in vain

Because the high-voltage SCR solid-state soft starter needs high-voltage high-power thyristor or series-parallel connection and electrical isolation technology, the technology is complicated and the cost is high, and its price is as high as 5-10 times of the liquid resistance, resulting in the high-voltage SCR solid-state soft starter being neglected for a long time

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