The starting method of the three-phase induction motor star-delta starter

Abstract

The invention provides a three-phase induction motor star-delta starting control method and device. The device comprises a current and voltage detection unit, a single-chip microcomputer control unit, a human-computer interaction unit, a delta connection switching device based on a solid-state relay and an AC contactor, a star connection switching device based on the solid-state relay, a main circuit AC contactor and a thermal relay device. The current and voltage detection unit is connected on a bus and used for detecting power current and power voltage signals in real time so as to act as the basis of trigger control of the single-chip microcomputer control unit. The single-chip microcomputer control unit is connected with the current and voltage detection unit. The human-computer interaction unit is connected with the single-chip microcomputer control unit. Starting current of the starting instant of star connection can be effectively suppressed so that the current impact of star-delta switching can be reduced, the electromagnetic interference caused by disconnection of a stator winding in the star-to-delta process can also be reduced and thus noise and vibration of starting of an asynchronous motor can be greatly reduced.

Description

technical field [0001] The invention relates to the field of power electronics and electric transmission, in particular to a star-delta starting method and a starting device for a three-phase induction motor. Background technique [0002] Three-phase cage-type asynchronous motors with large capacity usually adopt the reduced-voltage starting method. The reduced-voltage starting methods include: star-delta starting, stator winding series resistance decompression starting, autotransformer decompression starting and Yanbian delta decompression starting. Star-angle decompression starting means that when the motor is started, the stator windings are first connected into a star shape to reduce the starting voltage and current; after the motor starts, the speed rises close to the rated speed, and then the stator windings are disconnected. , and changed into a triangle, so that the motor runs at full voltage. In the starting process, the star-delta starter can reduce the starting c...

AI Technical Summary

Problems solved by technology

[0003] However, during the star-to-corner switching process, since the rotor winding has a DC free component, when it is re-connected to the power grid after being connected to a delta shape, an instantaneous impulse stator current may be generated, so that the peak value of the transient current exceeds the starting value in the most unfavorable case. peak current

At the same time, the induction motor is a strong inductive load when starting, and it may cause a large surge current if the input timing is not appropriate at the star start time.

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