Research Of Power Supply Circuit Of High Pressure Casing Core Drying Equipment

Due to the characteristics of high efficiency and low energy consumption,high frequency medium heating method has been widely concerned by all walks of life in recent years,and has been widely used in various fields such as wood,medical treatment,plastic heat sealing,food and so on.In this paper,the drying method of insulating paper layer of high-voltage bushing is changed from traditional heat conduction drying method to high-frequency medium heating method,which is a new idea and has not been implemented at home and abroad.The high frequency medium power supply adopts 380 V three-phase AC input,so the working frequency,output voltage and matching load of the high frequency power supply are directly related to the drying effect of the insulating paper layer of the high voltage bushing.The new high-pressure casing drying equipment test prototype consists of three parts,namely,automatic control system,high-frequency generator and vacuum tank.This paper mainly designs the high frequency generator of the prototype.According to the circuit principle of high frequency boost and high frequency oscillation,the rectifier filter circuit,oscillation circuit,filament voltage stabilizing circuit and control circuit of the high frequency generator are analyzed and designed in detail,the parameters of the high frequency generator are determined,and the prototype is debugged.Among them,the three-phase full bridge rectifier filter circuit is selected for the rectifier filter circuit,the FU-834 Sa electronic tube inductive coupling self-excited high-frequency oscillation generator is selected for the high-frequency oscillation generator,and the resonant single-phase magnetic saturation voltage regulator is selected for the filament stabilized power supply of the electronic tube to provide 7.5 V power supply.When the AC 380 V power supply fluctuates ±10%,its stabilized output voltage fluctuates 7.5 V less than 2%.Input parameters of high frequency generator: three-phase 380 V/50 Hz.The output parameters are: the oscillation frequency is 6M Hz adjustable,and the oscillation power is 0~30 kW.The performance index of the high frequency step-up transformer is 1:26,which can realize the adjustable high voltage output of 10 kV.The cooling mode of the electronic triode is: forced water cooling is adopted for the anode of the electronic tube;forced air cooling is adopted for the grid joint and filament electrode joint of the electronic tube.The high frequency generator can be used in the concentric cylinder medium,and the output characteristics of the high frequency medium power supply remain basically unchanged after the load is connected.The total power of the high-pressure casing drying device is about 90 kW.When the real air space is 3000 Pa and the drying temperature is 100℃±5℃,the drying time of the casing core can be shortened from 100 hours to 72 hours.The device requires constant temperature and humidity for the surrounding environment.The constant temperature is 23℃ and the constant humidity is 30%.Compared with other high-pressure casing drying equipment,it improves drying efficiency,saves cost,reduces energy consumption,and achieves the purpose of this paper.