Study Of Industrial Power Microwave Power Supply

Microwave technology is used more and more widely in modern industry, whichhas obvious advantages compared with conventional heating techniques. Therefore,more attention is paid to microwave technology equipment, and the scope of marketapplication is also expanding. Enhancing the performance of microwave power outputdevice is one of the key problems to microwave technology which is widely applied.The magnetron driving power supply directly affects the performance of themicrowave power output device.This paper expounds the magnetron for microwave heating principle, andintroduces the development status of microwave power source at home and abroad.The paper analyses the topological structure of microwave power supply that iscommonly used. Magnetron power supply in this paper adopts a new design scheme,which can adapt to different requirements of magnetron drive. Furthermore, the usercan adjust the microwave output power according to the demand. In order to prolongthe service life of the magnetron, the filament current control of the magnetron isstudied. In order to conveniently adjust the filament current, the scheme is used,which is that the circuit of the magnetron anode high voltage and the circuit of thefilament power supply are independent. To achieve soft switching technology andimprove the efficiency, magnetron anode high-voltage part adopts full bridge seriesresonant structure, and the filament power supply circuit adopts half-bridge seriesresonant structure. The mathematical model of series resonance circuit is established,and circuit design is optimized by selecting the appropriate resonant parameters.Meanwhile, the resonant circuit is simulated by using simulation software Pspice,with the selected parameters verified. The PWM frequency and the voltage transferratio of anode high-voltage circuit are changed by an external input voltage signal tocontrol the microwave power. The sampling current of the anode voltage circuit is coupled back to the half-bridge resonant chip L6599through filament power supplycircuit to control the magnetron filament current. The higher of the microwave power,the filament current is small.According to the theoretical calculation and simulation results, an experimentalprototype is made. The maximum output voltage of anode voltage circuit ofmicrowave power supply is5000V, the maximum output current of which is1A, andthe maximal voltage of the filament is20V, with16A~20A of the filament current.Microwave power can be adjusted in the range of1500W, more than92%efficiency.The experimental results verify the rationality and feasibility of the theoreticalanalysis and design.