Research On A Shunt Zero-current-switch Full-bridge Dc/dc Converter

Soft-switching technology presents one of the directions for power electronic.It is effective to solve the problem of switching loss and noise, and greatly improved the switching frequency. Meanwhile, it is used to reduce circuit EMI effectively, which plays more important role with the increase of power conversion and frequency.The soft-switching techniques of the Buck full-bridge converters have been studied extensively, but less attention has been paid to the Boost FB converters.With the development in technology and the electricity industry, today more and more equipments need high voltage and high power supply.Compared to Buck FB converter, the Boost FB converter has more advantages.So doing research to the soft-switching techniques of the Boost FB converter has important theoretical meaning and practical value.This paper introduces development process of the soft switching technology and analyzes operating principle of the conventional phase-shifted full bridge.For FB PWM DC/DC converter used IGBT in high power place, ZCS is better than ZVS,then determines the research target of this paper.Zero-current-transition full-bridge DC/DC converter realizes the ZCS of leading-legs and the ZCS of lagging-legs,which has improved the conversion efficiency and condition of soft switch of converter.The paper proposes a novel ZCT FB DC/DC converter.The converter uses PWM and is improved by adding the shunt active auxiliary circuit which is composed of a capacitance and an inductance in the primary winding.When the state of the switches changes, it not only achieves ZCS for the main switches and auxiliary switch,but also realizes soft commutation for the output rectifier diodes by controlling the active auxiliary circuit current, and makes the output rectifier diodes to endure low voltage, just being equal to the output voltage.This converter is very attractive for high power application where IGBT is predominantly used as power switches,eliminates the switching loss caused by the IGBT's tail current,and improves the circuit's performance.The principle of the novel converter is analyzed, and the foundations of parameter-design are presented.Futhermore, parameter calculation formulas at different modes are deduced. Based on state-space averaging combined with the characteristics of this circuit, the small-signal model of improved converter is established.Then the paper finishes the compensation design for the converter's dynamic and stability. A simulation is performed successfully to analyze the converter's working characteristics using Saber. The circuit analysis and design feasibility are verified by the simulation results.Based on the theoretical research, this paper carries on the experimental research about the novel boost FB ZCT converter.This paper expounds the design process of main circuit, controll circuit as well as drive circuit in details. In experimental, the main circuit, control circuit and drive circuit are debugged step by step. The typical waveform showing the performance of the system has been gained, and the correctness of theoretical analysis has been verified by analyzing the tested waveform...