Research On Phase Shifted Full Bridge Electric Propulsion Power Supply Based On Interleaving Parallel Technology

Phase-shifted full-bridge topology has been widely used in early spacecraft electric propulsion power supplies due to the advantages such as easy implementation of soft switching,simple structure,and good EMI characteristics.Nevertheless,there still exist many aspects in the full-bridge topology that need to be improved,such as the difficulty of achieving ZVS by the lagging bridge arm,the loss of duty cycle on the secondary side of the transformer,and the difficulty of eliminating the input current ripple.The traditional phase-shifted full-bridge converter is put forward based on the Buck topology,and its basic circuit is equivalent to a Buck converter.If it is required to have high-voltage output capability,it will generally be achieved by increasing the transformer ratio.However,when the ratio of the transformer becomes relatively large and the withstand voltage level of the secondary rectifier diodes becomes relatively high,the parasitic inductance and parasitic capacitance on the line will become larger.These parasitic elements will resonate during the switching process,which will then enlarge those above disadvantages and affect the performance of the converter.Therefore,it is particularly important to study an improved soft-switching phase-shifted full-bridge topology suitable for highfrequency,high-power,high-voltage output applications.A new and improved phase-shifted full-bridge topology is proposed based on the investigation and analysis of the existing PSFB derived topology.An auxiliary current source network is added to the full-bridge circuit and the interleaving parallel control strategy is adopted.The applicability of the proposed converter is theoretically verified by analyzing the working principle and steady-state characteristics of the circuit,and then the circuit parameters design and models selection are performed.The consistency of the simulation results with the theoretical analysis is verified based on the Saber simulation software.Finally,the small-signal modeling of the phase-shifted full-bridge topology is performed by the state space averaging method,and the corresponding open-loop transfer functions are obtained and the loop compensation is designed to prepare for the design of the closed-loop system.An experimental platform is set up based on the simulation results,and the circuit adopts phase-shift control based on the double closed-loop.The open-loop experiment shows that the proposed converter can output specified voltage and specified power under rated input conditions,and has good soft switching characteristics.That is,it can achieve ZVS in the full load range,and the input current ripple is also significantly eliminated.The subject effectively solves some inherent problems of the traditional PSFB topology,and the circuit design is reasonable.The closed-loop simulation results show that the designed closed-loop compensation has obvious correction effect and can re strain many kinds of disturbances for the system.