Research On Zero-Current-Transition Phase-shift Full-bridge DC/DC Converter

With the advancement in technology and the electricity industry, switching supply has been widely used in electricity,aerospace industry, communication etc. And it has been a very active hot technology. Nowadays, high performance, high efficiency and light weight are the most important performance figures of all kinds of converters. But the conventional converter operates in hard switching, low switching frequency and low efficiency. These reasons severely constrain the switching supply to miniaturization, modular direction. So the soft-switching Pulse-Width-Modulation (PWM) technology is proposed. And it makes converter to operate in high efficiency and high frequency as possible. Especially, the phase-shift control full-bridge PWM converter attracts more attention.This paper briefly introduces development process of the soft switching technology and analyzes operating process and disadvantages of the conventional phase-shifted full bridge Zero-Voltage-Switch (ZVS) PWM DC/DC converter, such as the narrow ZVS range, the severe loss of the duty, the severe secondary side rectifier voltage rings and low conversion efficiency etc. For full-bridge PWM DC/DC converter used IGBT, Zero-current-switching is better than Zero-voltage-switching. An improved Zero-Current-Transition (ZCT) phase-shift full-bridge DC/DC converter is proposed. The converter is improved by adding the active auxiliary circuit which is composed of the capacitance and the inductance in the primary winding. When the state of the switches changes, the ZCS ranges of the main and the auxiliary switches are achieved, and the switching loss caused by the IGBT's tail current is eliminated by controlling the resonant current of the active auxiliary circuit. In addition, the proposed converter reduces the diode reverse recovery energy loss. It also suppresses the primary circumfluence waste and avoids the great loss of duty cycle of conventional ZVS full-bridge converter to a certain extent.The operating principle and soft switching achievement condition of converter are analyzed in detail. The topology and parameters of main circuit are given. Based on state-space averaging combined with phase-shifted control mode and characteristics of soft-switching resonant circuit, the small-signal model of improved converter is established. This model is used to analyze stability and dynamic of the new converter.Based on the analyzing of the theory, simulation of the improved converter is researched, and the main circuit, the drive circuit and parameters of components are designed. The magnetic components and filter circuit of converter are analyzed in detail especially. Based on the control circuit composed by TMS320LF2407 DSP, the arithmetic to create shifting PWM and protection function are proposed. Utilizing the new generation driver integrated circuit IR2113 which is released by the Unites States IR company, the paper optimizes the circuit by adding two passive devices, based on the research of the conventional driver circuit. The improvement makes the chip to produce negative bias voltage, conquers the IR's disadvantage.To validate the performance of the improved Full-bridge ZVT PWM DC/DC converter, a prototype has been made. Experiments have been carried out. The simulation and experimental results show the correctness of the theory and the feasibility of the design.