Research On Strategy Of Soft-Switching For Current Source Full-Bridge PWM Converters

With the rapid development of power electronics technology, switching mode power supply obtains continuous progress and innovation. The DC / DC converter obtains more widely used in switching mode power supply. Among them, the full-bridge PWM converter as a typical DC / DC converter is widely used in high voltage and high power applications. However, with the development of high frequency, the traditional PWM power converter operating in hard switching mode, so that the circuit loss and EMI problem is exacerbated. So the soft-switch technology is proposed, voltage source full-bridge PWM converter and current source full-bridge PWM converter are two typical full-bridge soft switching circuit. However, based high voltage and high power applications on IGBT, its tail current makes ZCS better than ZVS. And the life of the electrolytic capacitor limits greatly lifetime of the voltage source converter. Thus these reasons cause that the current source full-bridge PWM converter compared to the voltage source full-bridge PWM converter has more room for development and advantages. Due to the commutation of lagging legs and duty cycle loss and other issues are found in the traditional current source full-bridge PWM converters. Therefore, this paper adds secondary circuits in the conventional circuit and studies for this circuit after the optimization and improvement.This paper outlines the development trend of switching mode power supply firstly. Also it discusses the importance of soft-switching technology for switching mode power supply. Secondly, this paper respectively describes work features of the traditional current source full-bridge PWM converters and two kinds of improvement topology more typically. Then, a novel current source full-bridge PWM converter with auxiliary circuits presented in the summary of previous experience. In this paper, the working principle and the topology of this converter are introduced. Next, the driving circuit with the core of DSP is introduced. Finally, the working condition of the converter is introduced through PSpice simulation and experiments on the actual device, so the theoretical analysis and practical feasibility are well proven.