Design Of DC High Voltage Power Supply Based On TMS320F28069

The disadvantages of the traditional 50 Hz DC high-voltage power supply such as large volume,heavy weight,low efficiency and inflexible control restrict the further application of DC high-voltage power supply in industrial production.Digitization can improve the intelligence of the control.High frequency can reduce the size of the transformer,but the high frequency can bring about a large switching loss.In view of the above problems,this paper design a high-frequency DC high-voltage power supply based on soft switching and digital control technology,but its digital processing speed is not fast enough,and soft-switching is only a closed-loop soft switch under specific load.Therefore,this paper chooses floating-point TMS320F28069 chip as the main control chip of the control circuit.The main frequency of this chip is 90 MHz,and the processing speed is fast.Closed-loop soft switching can be implemented from no-load to full-load by using the control methods of PFM and PWM.The specifications of the high-frequency DC high-voltage power supply are that rated working voltage is 60 kV,rated operating current is 17 mA,and operating frequency is between 25 kHz and 35 kHz.This paper makes a detailed analysis of the main circuit topology of high-frequency DC high-voltage power supply,and focusing on specific implementation schemes and selecting the corresponding devices of the rectifier circuit,high-frequency inverter circuit,high-frequency high-voltage transformer,high-frequency high voltage doubler rectification circuit.According to the complicated problems of high-frequency high-voltage transformer that have large parasitic parameters,this paper conducts the transformer models,analyzes the transformer leakage inductance and distributed capacitance,designs the transformer winding structure,and selects transformer core using the AP method;According to the design parameters of the transformer to determine the original and secondary side turns.Taking into account the skin effect,selecting the high-frequency high voltage transformer enameled wire specifications;Combined with distribution parameters of high-frequency high-voltage transformer,this paper analyzes the LCC resonant soft switch technology,and determines the LCC resonance parameters.According to different loads,frequency conversion control is the main method.According to the voltage fluctuation under a certain load,a repetitive control algorithm is used to achieving a variable duty cycle control for the purpose of stable output voltage,so that the DC high voltage power supply can achieve high frequency soft switching.and high control accuracy.Based on the theoretical analysis,a closed-loop simulation model of DC high-voltage power system was built by Simulink simulation tool in MATLAB.The simulation results verify the feasibility of the theoretical analysis.In order to achieve intelligent digital control,a digital control circuit based on the TMS320F28069 chip was designed to sample the voltage and current,judge the overvoltage and overcurrent,and protect the system in real time and implement the control algorithm.The software main program,interrupt program and control program of the control system were programmed.Combined with the design of the main circuit and control circuit,the prototype of the power supply was made and debugged.The experimental results verify the correctness of theory and simulation.