A Wide Output Range Full-Bridge Converter With Secondary-Side Phase-Shifted

The problem of environmental pollution is increasing, the electric car industry has been developed rapidly. In the electric vehicle charging system, the output voltage range of the former PFC device is limited and the intermediate level DC-DC converter is required to meet the charging demand. The topology of the PSFB(phase shifted full bridge) is simple, the loss of the switching is small, the reliability is high. In this paper, the high power density full-bridge DC-DC ZVS converter based on secondary-side phase-shifted control is studied.Firstly, after fully analysis and study of different kind of PSFB, the paper presents a high power density full-bridge DC-DC converter based on secondary-side phase-shifted control. The output rectifier diode voltage spikes is restrained by the clamp effect of the output capacitor while improving the reliability of the topology, the output capacitor resets the primary idle current, and eliminate the circulating loss. By adding the passive auxiliary network, the switches can realize the ZVS soft switching under wide range load, which can effectively reduce the switching loss and improve the converter efficiency.The mathematical model of the phase shift angle and the converter power and the output voltage are established. The effect of the circuit parameters on the output characteristic and soft switching condition is defined. By comparing all working states, the backflow power of DCM working state is 0. Through the optimization design of the parameters of the circuit, the circuit works in expected state. Primary and secondary-side switches achieve ZVS soft switching in wide range of load current conditions. Small signal model of the converter is established by Switching periodic averaging method. The second order small signal model is compared with the first order small signal model, and based on the first-order small signal model, the rational design of compensation network and the closed loop system control circuit is designed, ensuring stability and dynamic of the closed-loop systems.The research contents of this paper are verified by simulation and experiment. An input voltage 100 V, output voltage 200 V-400 V, frequency 100 k Hz experimental prototype has been designed. The waveforms of the primary inductor current are tested, and the theoretical analysis and simulation results are verified. Secondly, the soft switching characteristics of the switches are verified in DCM state under different load of 200 V and 400 V. Finally, the stability and rapidity of the closed-loop control system is verified.