Research On Key Technology Of Resonance-based High Voltage Dc Converter And Prototype Development

In the leakage current test of new high voltage capacitor,a precise DC high voltage power source with high stability and high efficiency is needed.However,the traditional DC high voltage power source based on PWM working principle has the problems of large switching loss and large output voltage fluctuation,which is difficult to meet the requirements of highperformance test.In this dissertation,the key technologies of high voltage DC/DC converter based on LLC resonant principle are studied,and the LLC high voltage DC power source system prototype with high-precision and low ripple performance is developed,which has the power of 200 W,output voltage adjustable from 200 V to 1000 V.The main research contents of this paper include: the main factors that restrict the high voltage and wide range output capability of LLC resonant converter are studied,and the high voltage power source topology of active power factor correction(PFC)+ LLC resonant cavity+ multi-winding transformer + voltage-doubler rectifier circuit is proposed;Aiming at the reflection effect of the load circuit in the back stage of LLC resonant cavity,an overall steadystate model of integrated LLC resonant cavity + boost circuit based on fundamental wave analysis method is studied,and according to the overall steady-state model,the LLC resonant circuit suitable for high voltage applications is optimized;Finally,based on the extended description function method,a small signal dynamic model based on LLC resonant converter and voltage-doubler rectifier circuit is proposed,and a closed-loop compensation control scheme is designed.An LLC high voltage DC power source prototype based on STM32F103 and UCC25600 is developed.The performance tests show that the output voltage of the prototype can be adjusted from 200 V to 1000 V,the full load efficiency of 200 W is more than 90%,and the voltage accuracy in the full load range is higher than 0.5% F.S ± 2 V,the output voltage resolution reaches 1%,the ripple coefficient is less than 1%,the full-scale load adjustment rate is less than 0.5%,and the performance of the prototype reaches the expected goal.