The Research Of Asynchronous Motor Soft Starter Based On ATmega128

In view of problems of three-phase asynchronous motor direct and traditional starting methods, this paper introduces a kind of motor soft starter with high performance and intelligence based on AVR ATmega128 microcontroller and thyristors. The soft starter which has merit of simple structure, friendly interface, reasonable control strategies, intelligent control algorithms, complete functions and good control performance starts up the motor smoothly.Firstly, this paper introduces the development status and prospects of soft-start technology at home and abroad. After analyzing inherent start features of the three-phase AC motor and working principle and control strategy of the soft starter, the models of asynchronous motor traditional starting system and soft starter system based on voltage regulation are established and simulated by MATLAB. The simulation results which are compared and analyzed lay a solid theoretical foundation for the design of the soft starter.Secondly, this paper describes the hardware circuit and software design of the soft-start system in detail. In the hardware circuit design, the diagram of the main circuit and control circuit are given, and detailed analysis is carried out for its working principle; in the software design, using modular design, the software implementation schemes and program flow charts of various functional modules, control algorithms and soft-start modes are given.Finally, using the equipments of the laboratory, a series of debugging for the soft starter was carried out. The experimental waveforms and data are analyzed. The results show that the soft starter could start up smoothly and reliably, and the starting current of the asynchronous motor is controlled.