A Research On DC/DC Power Supply Based On Soft Switching Half-bridge Circuit

DC/DC switching power supply because of its good performance, and obtaining of one or more available the stable DC output voltage, so it have been widely used in the remote data communications, computer, automation equipment, military, aerospace and other fields. Nowadays, with the decreasing in dimensions of the electrical equipment, the requirements in weight, volume and dimensions for the power supply are increasingly stringent. And the development of soft-switching technology is an important way to reduce the high-frequency isolated DC/DC power supply’s weight and volume, which is now the research hotspot of isolated DC / DC power supply. The article mainly researched and analyzed of soft-switching technology in half-bridge DC/DC power.Firstly, introduced the soft-switching technology, and analyzed some basic soft-switching unit, and have a detailed study of two popular half-bridge soft-switching circuits. Then put forward a new soft switching circuit of this paper, and have a detailed analysis of its operation mode, and have done comparison with the popular two soft-switching circuits with pointing out their advantages and disadvantages.Secondly, researched the control strategy of proposed new soft switching circuit, analysis of the control strategy in half-bridge inverter, and the characteristics of PWM and PFM modulation method. Identified the inner ring with PFM method, the outer ring with PWM method. Wherein the PFM system can make power tubes to achieve zero current shut-down, PWM outer ring can stable the system output voltage.thirdly, built SIMULINK simulation model of the main circuit and did simulation to verify the feasibility of the control strategy, and counted the impact of duty cycle and frequency on system in PFM and PWM modulation, obtained mutual relations when the PWM and PFM were modulating together.Then designed system‘s hardware and software depending on the circuit’s operation mode. Hardware includes system main circuit, current and voltage sampling circuit, drive circuit. And designed the direction and magnitude of adjust in software according to the control strategy and simulation results.Finally, constructed the experimental platform according to the design, and proved the feasibility of the control scheme and design parameters by experiment. The control method not only can make power tubes to achieve zero current turned-off, and losses during switching of the system can be reduced, but also can achieve the stable output system.