Research On Low Loss Pulse Power Supply For WEDM

Pulse power supply is the energy "heart" of high speed wire electrical discharge machining(HS-WEDM),which directly affects the overall machining performance.Now,most of the pulse power supply features low efficiency,poor controllability of discharge current and small range of energy regulation,which directly restrict the machining performance improvement and the optimization of the processing parameters.In this thesis,a new pulse power supply is designed based on power electronic technology.The main power circuit adopts four interleaved parallel synchronous rectifier Buck circuit,and a Buck converter with energy feedback circuit for finishing cutting.The FPGA digital controller is used to generate the PWM drive signal and complete the communication with the upper computer.The high-speed voltage and current sampling circuit provides the feedback signals.The pulse power supply can control the output discharge current waveform,pulse width,pulse interval flexibly,and provides triangle wave,sawtooth wave and rectangle wave for machining.Furthermore,in order to improve the machining efficiency,a new real-time discrimination method of gap-status(no-load,normal discharge,short circuit)based on the analysis of the gap voltage and current in actual machining.This method can be adopted freely for the varying pulse ratio,and accurately identify the gap discharge state of each machining cycle in real time.Therefore,the pulse power supply can identify and deal with the harmful pulses in time,and ensure a stable and high speed cutting.