Single-stage Single-phase Large Boost Quasi-Z Source Three-port Photovoltaic Independent Power Supply Syste

Under the background of "carbon neutrality and carbon peak" era,solar photovoltaic power generation has become one of the most potential new energy power generation methods due to its rich resources,environmental protection,and low cost.Impedance source inverter has the advantage of single-stage power conversion with shoot-through ability,which has attracted wide attention in the field of photovoltaic power generation.However,the multi-peak characteristics of PV modules in series make it difficult to track the maximum power point of PV array.Although PV modules in parallel have single peak characteristics,the output voltage of PV array is lower.The voltage gain of traditional impedance source inverter cannot meet the requirements.In addition,there are some problems of the impedance source photovoltaic inverter such as unstable output power,large switching loss,and large volume and weight.Therefore,it has important theoretical value and application prospect to seek an impedance source photovoltaic independent power supply system with high voltage gain,small volume and weight,soft switching and continuous reliable power supply.Based on the discussion of the existing impedance source inverters and three-port schemes,a single-stage single-phase quasi-Z source three-port photovoltaic independent power supply system with high voltage gain is proposed in this paper.The key technologies such as circuit topology,energy management control strategy,steady-state principles,soft-switching implementation,and magnetic integration scheme,etc.,are analyzed theoretically and verified by simulation and experiment.Important conclusions are obtained.The proposed photovoltaic independent power supply system topology is composed of magnetic integrated impedance network,soft-switching auxiliary network,battery auxiliary port paralleled to the energy storage capacitor,single-phase inverter bridge,and input and output filters.The maximum power output energy management control strategy with photovoltaic MPPT and instantaneous feedback of input voltage and output voltage is adopted.The magnetic integrated impedance network is composed of a magnetic integrated inductor,four energy storage capacitors,and two diodes.Where,the magnetic integrated inductor integrates three energy storage inductors into a UIU magnetic core,which is made of two magnetic powder cores and a ferrite.The soft-switching auxiliary network is composed of a resonant inductor,a clamping capacitor and a switch.The system has three power supply modes,which include photovoltaic and battery power supply to load,photovoltaic power supply to battery and load,and battery power supply to load alone.A high frequency switching process comprises nine working intervals.The process analysis of high frequency switching and the conditions of soft switching are given.The voltage transfer ratio is derived and the design criteria of key parameters are analyzed such as magnetic integrated impedance network,soft-switching auxiliary network,voltage and current stress of power switches,and the filters,etc.A 1kVA 96VDC/220V50 HzAC prototype of the proposed photovoltaic independent power supply system is designed.The simulation results of PSIM and the dynamic and steady-state experimental results show that the proposed system has the advantages of single-stage power conversion,high voltage gain,zero-voltage-switching of all switches,high conversion efficiency,small volume and weight,strong load adaptability,smooth switching of three power supply modes,and reliable power supply.It has a wide application prospect in inverter occasions such as solar photovoltaic power generation with low input voltage or large input voltage variation range.