Research On High Power Microwave Power Supply For MPCVD Equipment

The microwave plasma chemical vapor deposition(MPCVD)method for synthesizing synthetic diamond has become the mainstream method of synthetic gemgrade diamond film in recent years because of its clean synthetic environment and high plasma output efficiency.In order to make the microwave plasma equipment power source output stable and reliable,it needs a high-performance power supply that works with it.The traditional magnetron microwave power supply is the power frequency linear power supply scheme.This scheme has a simple structure,but because the power frequency operating frequency is too low,the power supply efficiency is low and the volume is large.The general switching power supply has poor anti-interference ability and large output ripple,which cannot meet the performance indicators of the highvoltage microwave power supply of MPCVD equipment.In this paper,after the basic theoretical research of switching power supply,combined with the technical parameters of the microwave source 2450 MHz magnetron,the high-voltage power supply system of the microwave power supply is designed.This article adopts digital control method and applies sliding mode variable structure control technology to the high-voltage power supply control system of MPCVD equipment to replace the traditional PID analog control,so that the power supply can better resist input voltage fluctuations and load changes during operation.The interference brought by it improves the performance of the power supply.The main circuit part of the power supply adopts the topological structure of a full-bridge converter,and uses soft switching technology to reduce switching tube losses and further increase the efficiency of the power supply.The control part adopts the MKV31F256VLH12 control chip with DSP operation unit,and sets the output parameters of the power supply through the host computer.It outputs the four-channel PWM signal to the drive circuit through the digital control value read,so that the power system generates high-voltage output and realizes Stable regulation of voltage output.At the same time,in order to better protect the power supply system,a protection circuit is designed in the circuit to ensure the safety of the equipment.This paper also uses Matlab/simulink software to model and simulate the two schemes of phase-shifted full-bridge converters using traditional PID control and sliding mode control to verify the design effects.Finally,a power supply sample was made for experiments.The results showed that the power supply sample basically meets the design specifications.The technical specifications of the power supply are:input is three-phase alternating current at power frequency,output is adjustable 6500-8000 Vdc,output current is 0-1.3A,maximum The output power is 8k W,the stability of the high-voltage output is below 0.5%,and the ripple size does not exceed 0.5%.