To Research And Realize The Quasi Square Wave Magnetic Field Of Asynchronous Electromotor

With the development of power electronic technology which based on power electronic device, and the development of AC motor control system, the regulating technology of asynchronous motor develops quickly. Traditionally, the magnetic field of asynchronous motor shows as a sine wave which has advantage. However, it is not the best one. The quasi square wave magnetic field technology is brought out in this paper. Compared with the old one, it can improve power output and motor efficiency.Starts from basic equations of asynchronous motor, firstly, this paper give out the wave forms of voltage, currents, and power output and motor efficiency under quasi square wave Magnetic Field. So is the Mechanical character of VV, VVVF, VF.In the paper, the magnetic field of quasi square wave control system is designed using DSP as the core. Trapeziform wave input voltage which could improve the exciting current is produced by parallel connecting capacitance. Experimental result is consistent with the theoretic one. Inverter circuit using IGBT is suit for small and middle power motor, while inverter circuit using thyristor is suit for high power one. In order to turn off thyristor unfailingly, the inverter circuit should be rebuilt. At last, three methods are brought out, using LC circuit to add reverse voltage, using additive power supply to add reverse voltage, and using LC circuit to barter current. Each has its advantage and disadvantage.