The Research On Full-Bridge Soft-Switching Power Supply For Microplasma Oxidation With Wide Range Output

Because the technique of Micro-plasma oxidation has several merits: simple flow, high treating efficiency and little environmental pollution, it has promotion patent and broad applied foreground. With its development, power supply becomes high frequency, high power and high efficiency at the same time. Using soft switching technique, DC-DC full bridge converter can provide more power and decrease loss of switching device, and efficiency of power supply is improved. It is most important part of researching DC power supply for Micro-plasma oxidation.Because input bulbar voltage is high, IGBT is selected in the paper. According to trailing current of IGBT, switching frequency is determined. Through analyzing and comparing merits and faults of various ZVZCS converter topology, the ZVZCS converter setting blocking capacitor and saturable inductor in the primary is designed in the paper. With the help of transformer leakage and filtering inductor, ZVS of leading-leg switches is realized in wide range of load. The voltage of blocking capacitor is added to leakage of transformer and the primary current is reset, and then ZCS of lagging-leg switches is realized in whole range of load. Through analyzing mode of converter, we know that maximum duty cycle is restricted.The functions and design methods of resonance permanents are discussed in detail. Through connecting capacitor in parallel to the leading-leg switches, switching loss of leading-leg switches is decrease, and their relationship is discussed; The voltage of dc blocking capacitor as reverse blocking source help the primary current reset, and then the lagging-leg switches realize ZCS, and voltage stress of lagging-leg switches is heavier. Design principles of dc blocking capacitor are introduced also; Through analyzing loss of saturable inductor and discussing factors influencing its heat dissipation, method of decreasing the temperature of saturable inductor is presented.Base on UC3879 and adopting peak current link control, control circuit is designed. Modes of constant-voltage-limit-current and constant-current–limit-voltage are realized. The correction circuit is designed, and it improves dynamic...