| Rail welding is an important part of laying seamless lines,and its welding quality is the guarantee of railway traffic safety.The existing welding methods at home and abroad tend to be mature,but there are still deficiencies in turnout welding,so it is necessary to introduce new welding techniques and methods in the field of rail welding.Electron beam welding has the advantages of high energy and high efficiency in the aerospace field It has been widely used,and foreign companies have successfully conducted research on rail electron beam welding.Therefore,researching and summarizing the development and current status of the high-voltage power supply of the key technology of electron beam welding at home and abroad,improving the stability,efficiency and intelligent control of the high-voltage power supply of electron beam welding will help it get extremely important engineering promotion in the field of rail welding.This paper studies and designs a set of full-bridge LLC resonant inverter-type new high-voltage power supply system for electron beam welding based on DSP+FPGA control,which mainly includes two parts: main circuit and control circuit.The main circuit is composed of low-voltage inverter voltage regulation,high-voltage boost and silicon stack rectifier circuit.The low-voltage inverter voltage regulating circuit converts the 380 V three-phase AC through rectification and filtering,BUCK voltage regulation and full-bridge inverter,the output frequency is adjustable,and the voltage is adjustable.The AC square wave voltage is then input to the LLC resonant circuit and placed in the high-frequency high-voltage transformer in the fuel tank;the high-voltage step-up and silicon stack rectifier circuit boosts the low-voltage AC voltage,then passes through the high-voltage silicon stack rectifier filter circuit,and finally outputs 60 kV DC high voltage to be loaded into the electron gun.In this paper,the main components in the main circuit are calculated and selected,and the simulation model is built on the Simulink platform.The simulation results show that the design scheme is reasonable.The control circuit takes DSP+FPGA as the core and adopts a hybrid control strategy of BUCK voltage regulation and full-bridge resonance frequency modulation to realize the regulation and control of high-voltage power supply.The high-voltage output signal is sampled by the voltage-dividing sampling circuit,and the high-voltage feedback signal is obtained through the sensor.First,the high-voltage feedback signal is fault-discriminated by the FPGA,and the AD-converted signal of the fault-free voltage and current is sent to the DSP for PID calculation The PWM with adjustable duty cycle and adjustable frequency respectively drives and controls the BUCK circuit and the full-bridge inverter circuit to control the turn-on and turn-off of the IGBT in the main circuit to achieve closed-loop control,thereby achieving fast regulation and stable output of the high-voltage power supply.Combined with the working process of the electron beam welding high-voltage power supply system and the control method and control strategy proposed in this paper,the main control program and subroutine of the power supply system are compiled.The article analyzes the AD sampling program,PID adjustment program,PWM driver program and communication program in detail,and gives the program flow chart and some key program codes.The software and hardware joint adjustment of each module of the control circuit is carried out in the article.The debugging results show that the control circuit meets the design requirements of the electron beam welding high-voltage power supply system,and the performance is stable.Finally,the principle prototype of the electron beam welding high-voltage power supply system is built and debugged.The test analysis results show that the electron beam welding high-voltage power supply system designed in this paper basically meets the expected technical parameters and can meet the requirements of rail welding. |
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