Research Of Phase-Shifted Full-Bridge With Current-Double Rectifier Based On Synchronous Rectification

With the development of power electronic devices miniaturized and portable, the switch mode power supply(SMPS) as its core element is moving in the direction of high-frequency, high-efficient and high power density. To improve the efficiency of SMPS and reduce switching losses, a kind of phase-shifted full-bridge current-double rectifier based on synchronous rectification is analyzed and designed in this thesis,and the converter is extremely suitable for low-voltage high-current field.Firstly, the soft-switching technology characterized by having zero switching losses is discussed, and it's the key technology to improve the frequency of the switches in SMPS.Full-bridge phase-shifted circuit is the most widely used topology to achieve soft-switching process.Secondly,three types of rectifier are compared for selecting a topology that is most suitable for low-voltage high-current output, and the current-double rectifier with simple transformer structure but low losses is adopted in this paper. Meanwhile, through using synchronous rectification to drive the switches, the converter can work effectively by reducing switching losses furtherly.Then, the operating mode of phase-shifted full-bridge current-double rectifier is analyzed after determining it as the main circuit topology in this paper. And, the voltage overshooting and voltage oscillation due to the parasitic capacitance on the rectifier diodes is suppressed effectively by applied two clamping diodes in the primary side.Finally, each of the component parameters in the main circuit are designed,and the small signal mode of phase-shifted full-bridge current-double rectifier is established, then the controller composed of voltage and current double-loop is devised according to the small signal mode. At last, the correctness of the theoretical analysis and the feasibility of the proposed design methods is verified by MATLAB simulations.