Research On Soft-Switching Technology Of Phase-Shifted Double Full-Bridge DC-DC Converter

Compared to conventional chemical propulsion,ion electric propulsion systems can significantly reduce the weight and volume of propellant and have the advantage of high specific impulse,making them suitable for missions with high total flight impulse such as longlife,high-power communication satellites and deep space exploration.As the demand for high power and high efficiency power supplies in aerospace propulsion systems increases,beam supply,as an important component of the ion electric propulsion system power module,are also subject to higher performance requirements.This thesis investigates how to improve the performance of beam supply in combination with soft switching technology to achieve the design goal of high power miniaturisation.The details of the research are as follows.(1)The specific application background of the beam supply is analysed,and the improvement direction of the beam supply is given by analysing the research status of the beam supply at home and abroad.Combined with the application of soft-switching technology,a phase-shifted double full-bridge soft-switching topology is proposed.The structure and operating principle of the conventional phase-shifted full-bridge zero-voltage converter are analysed,and improvement directions are given to address the problems of the phase-shifted full-bridge zero-voltage converter,such as difficulties in implementing hysteresis-arm zerovoltage switching and loss of secondary duty cycle.The proposed converter topology and operating principle are elaborated,and the basic conditions for soft switching are analysed.(2)The specific design parameters of the beam supply and the selection of relevant device types are analysed in detail with regard to the specific design specifications of the converter.The parameters of the high frequency transformer,the resonant network,the direct isolation capacitor and the output filter network are included.A detailed analysis and design of the transformer is also presented,as well as the selection of the main power components involved in the circuit is given.(3)The common modelling methods for switching power supplies are analysed,and the proposed converter is modelled analytically using the state space averaging method to obtain its equivalent small signal circuit model.Then the open-loop transfer function of the system is further solved analytically on the basis of the established equivalent model.The compensation network of the control system is designed based on the frequency domain method,and the logarithmic amplitude and frequency curves of the system before and after the correction are given,and the corrected system has good performance.(4)Based on the theoretical analysis,the proposed dual full-bridge converter is simulated and verified and experimentally analysed.The simulation model was built in the MATLAB/Simulink simulation environment to validate the theoretical analysis.The simulation results show that the main circuit parameters and related design are consistent with the theory,and the power switching tubes operate in the soft-switching state.The experimental platform of the prototype is then built based on the specific design specifications of the beam supply,and relevant experiments are carried out on the prototype and the results are analysed.The experimental results are generally consistent with the theory and verify the rationality of the design.