Induction Motor Soft Starter

When AC motors start directly with full voltages, the current mayreach the magnitude as much as four-eight times of the rated current, whichmakes power system impactive and affect other apparatus on the same powernetwork. Moreover, the starting torque is twice as much as the rated torqueapproximately, therefore its load performance will be decreased as well.We control current in the start, have more importance of economy value.Based on these purposees, this dissertation does research on squirrel-cageAC asynchronous motor.Firstly, this thesis introduces the development of AC motor softstarter and gives an expatiation of the start on the operation principle.Then, on thebase of analysis and compare, it brings one way to accomplishthe motor soft starting, as well as the operation principle, the maincircuit design.Secondly, the hardware design and analysis of the soft-starter areintroduced, including the main circuit, control circuit, power circuit anddetect current circuit and discussed the software design of controlsystem.Including main program, synchronization signal interruptedsubroutine, drive signal interrupted subroutine, phase sequence detectionsubroutine, method subroutine and Key display subroutine. It also givesprogram flow charts.At the end of this dissertation, a model of soft starter system basedon voltage regulating is established and simulated with SIMULINK and POWERSYSTEM in MATLAB. The results of the simulation show that the system canreduce the high stating current as asynchronous motors start up directly...