Research On Current Source Type DC Asynchronous Motor And Soft Switching Converter

At present,in the field of electrical vehicles,there has been an application that we powera three-phase sunchronous motor with DC current source through a specially designeddriver,based on which,the new concept of current source DC asynchronous motor was putforward,which means the DC current source that differs from each other by120degreesbetween phases is used as a substitute of the traditional three-phase sinusoidal voltage sourceto power the stator windings of the asynchronous motor.The magnetic potential the DCcurrent produces rotates at a constant speed and has an fixed amplitude,which is required bythe normal performance of the motor.The relationship between the DC current source and the magnetic potential it produces isfirst analysed.Starting with the simple current wave forms,such as triangle,we find out thecorresponding relation between current wave forms and the magnetic potential,based onwhich the saddle current source is designed regarding the circular magnetic potential thatrotates uniformly which is required by the motor.The performance characteristics of theasynchronous motor is also analysed on the condition that saddle current source is employedas the power source.The topology of bail charge transferring zero current switching quasi-resonant converteris designed purposely as the current source of the asynchronous motor.High frequency pulsecurrent chain on the output capacitor is obtained through the energy storage and chargetransferring function of the bail capacitor,allowing the energy to flow from the power to theload.A suitable control method was put forward to track the current of the load by controllingthe IGBTs in the main circuit,aiming to get the saddle current waveform we need.The simulation of the tracking control of saddle current waveform of both single-phase and three phase is conducted by building models of the main circuit of the converter and thecontrol method using simulink.The simulation results shows that the main circuit and andcontrolling method is feasible in theory.The experiment of saddle current tracking control，both single-phase and three-phase,isconducted by building main circuit of the converter with hardware components.The controlmethod is verified by both analog circuits and programming with dsPIC singlechip.The speedregulating experiment is conducted with saddle current powering the asynchronous motor.The experiment result suggests that the circuit and control method is not only theroticallyfeasible,but can also obtain satisfactory effect in practical application.