Research On High Frequency And High Voltage Power Supply Based On Series-parallel Resonant Converter

High-voltage DC power supplies are widely used in industrial dust removal,medical equipment,aerospace and many other fields.The resonant converter is the core part of the high voltage power supply.It is always the focus of research to control the switching mode of the resonant converter to achieve soft switching characteristics.The phase shift control mode only allows the resonant converter to implement soft switching within a small load variation range.By analyzing the operating principle and steady-state characteristics of the LCC resonant converter in the continuous inductor current mode,the asymmetric phase shift control mode can achieve soft switching characteristics and reduce circuit losses in a wide load range.For the LCC resonant converter in the high-voltage DC power supply,the parallel resonant capacitor,the high-frequency transformer,the secondary-side rectifier bridge and the output filter capacitor can be equivalent to a complex impedance by the fundamental analysis method,thereby obtaining the equivalent circuit of the resonant converter,model.On this basis,the influences of key circuit parameters such as different switching frequency,input impedance angle and rectification turn-oflf angle on the steady-state characteristics of the converter are analyzed.The parameter design principle of the resonant converter is obtained,and a limited input impedance is given.The parameter design method of the angle.In the phase shift control mode,the resonant converter easily loses soft switching characteristics under varying load conditions,while the asymmetric phase shift control mode includes two control variables of duty cycle and phase shift angle,which has higher control freedom and can be softened.The load range of the switch.The asymmetric phase shift control method is used to analyze the steady-state characteristics of the output power,ZVS characteristics and resonant current of the resonant converter.The results show that the same output power can be realized by a combination of different duty cycles and phase shift angles,but different combinations.This in turn causes changes in soft switching characteristics and resonant current.Therefore,an eff-iciency optimization strategy is introduced.The voltage fuzzy adaptive PID closed-loop control and current optimization algorithm are used to correct the command value of the control variable,reduce the resonant current in the case of constant voltage output,and ensure the realization of ZVS.Improve the efficiency of the converter.In order to improve the eff-iciency of the resonant converter,a control method of asymmetric phase shifting is adopted.By controlling the duty cycle and the phase shift angle,the control of the switching tube is realized,and the degree of freedom of control is increased.The output power,soft switching and resonant current of the resonant converter under the steady-state environment are established as a function of duty cycle and phase shift angle.The output power of the resonant converter under different duty cycles and phase shift angles is analyzed.The trend of soft switching and resonant current.The analysis results show that the same output power can be realized by different combinations of control quantities,but different combinations will cause changes in soft switching and resonant current characteristics.Combined with the above analysis,the system simulation analysis and hardware circuit and software program design of the high-voltage DC power supply,the hardware part includes the design of the main circuit,the drive circuit,the detection circuit and the protection circuit;the software part includes the design of the main program and the interrupt service program.Through the Matlab/Simulink simulation comparison,the asymmetric phase shift control strategy can still achieve soft switching under 30%rated load,and has a wider soft switching load range.