Research On High Efficiency And High Power Density AC/DC Power Supply Based On Totem Pole Bridgeless PFC

AC/DC power supply is widely used in production,life and other fields,mainly including communication power supply,new energy vehicles and military equipment.With the increasing power consumption of equipment year by year,it is very important to design AC/DC power supply with high efficiency,small volume and light weight on the premise of maintaining power supply reliability.In view of the current requirements of high efficiency and high power density of AC/DC switching power supply,this paper first compares and analyzes the front stage power factor correction(PFC)topology and the rear stage DC/DC topology of AD/DC two-stage architecture.Using the topology scheme of totem pole bridgeless PFC+LLC resonant converter,the working principle and soft switching characteristics of totem pole bridgeless PFC in critical continuous mode(CRM)are analyzed.The scheme of zero current detection(ZCD)is analyzed in detail,and a digital ZCD scheme is proposed;Further,the primary and secondary side schemes of LLC resonant converter are selected,and the working principle and soft switching characteristics are analyzed.The front and back stages adopt digital control chip based on DSP tms320f28035 to replace the complex peripheral circuit required by traditional analog control.Secondly,for the specific application of AC/DC power supply with high efficiency and high power density,the two-stage architecture of totem column bridgeless PFC and half bridge LLC resonant converter is adopted.Optimize and analyze the two-level control scheme,auxiliary power scheme,heat dissipation scheme and main power components.A 220Vac to28Vdc AC/DC 600W prototype is designed.The overall efficiency of 94.6%and the power density of 110W/in~3 are achieved.Compared with the existing products with the same power level,the proposed scheme has obvious advantages and achieves the expected goal of high efficiency and high power density.Finally,for higher power applications,the interleaving stability and soft switching reliability are improved by using interleaving parallel scheme and digital ZCD strategy.It solves the shortcomings of high current ripple of single-phase CRM totem column bridgeless PFC inductance and large volume of differential mode filter,further improves the power density and light load efficiency of the converter,and verifies the feasibility of the design scheme through experiments.