Design On Full-bridge DC-DC Switching Power Supply In The Small Submarine Power System

Switching power supply converter technology has been rapidly developed in recent years. However, high-power switching power supply has not been applied in the field of needing one because the products of high-power switching power supply are scarce and the performances are poor in the domestic. With the development and use of new energy, such as solar and wind energy, fuel cell, high-power switching power supply becomes the focus of current research. Where, implement of high-power switching power supply depends on the development of DC-DC converter topology theory and soft-switch technology.The thesis analysises the four operation stages for full-bridge DC-DC converter, designs DC block capacitor which has solved the problem of the DC conduction and magnetic biasing. Thus the full-bridge DC-DC converter truly become ideal topology of high-power switching power supply. Establishing mathematical models of full-bridge DC-DC converter by choice of state-space vector, and then study on dynamic characteristic of switching power supply. The device has soft-switch’s advantage with low switching losses and EMI,also has hard-switch’s advantage with low voltage and current capacity and easy to filter owing to soft-switch and hard-switch combined. Voltage-mode PWM and PWM generator SG3525are selected in the control circuit, and design improved PI control compensation network. In sampling circuit, LEM voltage and current sensors based on Hall effect have realized isolation of the main circuit and control circuit, and fast response. Each power supply module operates in parallel through current-sharing chip UC3907for implement of high-power switching power supply. Modular switching power supply and redundant switching power supply system have been implemented as a result of current-sharing technology, improve the flexibility and reliability. Design the circuit without optocoupler between SG3525and UC3907, resulting in fast response. IGBT driving circuits have high driving power, simple structure and negative voltage shutdown.The paper is based on the research project submarine electric propulsion system. A laboratory prototype circuit with, output voltage600V and total output power30KW is implemented. And results are shown to confirm the validity of the designed switching device and the stability of running.