Parallel Time-sharing Power Supply Step-down DC Chopper Type Single-stage Multi-input Independent Power Supply Syste

The increasing shortage of fossil fuels such as coal,oil and gas and increasingly serious environmental pollution make energy and the environment a major problem facing mankind in the 21 st century.With the advantages of clean and pollution-free,cheap,reliable and abundant,new energy sources such as solar,wind,hydrogen,tidal and geothermal energy are increasingly attracting widespread attention from countries around the world.However,the single new energy power supply is limited by the climate,seasons and other conditions,and there are defects such as unstable power supply,discontinuity,and great environmental impact.In order to overcome the shortcomings of a single new energy power supply,improve the stability and continuity of power supply,and realize the full use and priority utilization of new energy,it is necessary to use a variety of new energy combined power generation systems.Therefore,the research on independent power supply systems for a variety of new energy combined power supply has important theoretical value and engineering application prospects.Based on the research status and development of independent power supply systems for multiple new energy joint power supply,this paper proposes a single-stage multi-input independent power supply system of parallel time-sharing power supply step-down DC chopper type.And the theoretical analysis,simulation and experimental research on the key technologies such as the topology structure,energy management control strategy,steady-state principle characteristics,power supply mode and its smooth switching,and design criteria of main circuit parameters of the system have been carried out,and important conclusions have been obtained.The proposed topology of the parallel time-sharing power-down dc chopper type singlestage multi-input independent power supply system is composed of a parallel time-sharing power-down dc chopper type single-stage multi-input inverter and a battery charge-discharge converter in parallel on the output side.A single-stage multi-input inverter consists of a singleinput,single-output combined isolated bidirectional buck DC chopper that connects n-inputsource four-quadrant time-sharing switching circuit with an output LC filter.It adopts the maximum power output energy management SPWM control strategy with the input voltage outer loop of the photovoltaic MPPT and the output filter inductor current inner loop.Battery charge and discharge converter is a single-stage Buck/Boost type high-frequency link inverter/rectifier.It employs a rectified unipolar phase-shifting SPWM control strategy with output voltage DC bias correction.This power supply system has three power supply modes:multi-channel new energy and battery power supply to output load,multiple new energy supply to output load and battery at the same time,and multiple new energy independent output load power supply Depending on the magnitude of the input and output power,the system automatically operates in one power supply mode and enables smooth and seamless switching between the three power supply modes.Single-stage multi-input inverters have 10 operating intervals in a high frequency switching cycle during forward and reverse energy transfer.The battery charge-discharge converter has 8 operating intervals in a high frequency switching cycle.This paper presents the voltage transfer ratio,out-of-two-quadrant characteristics of multi-input inverters,and the out-of-four quadrant characteristics of charge-discharge converters,as well as design guidelines for key circuit parameters such as high-frequency transformer turns ratio,active clamp capacitance,resonant capacitance,power switching voltage and current stress,and input and output filters.Using the proposed circuit topology and energy management control strategy,the experimental device of 3k VA 240-360VDC/220V50 Hz AC parallel tick power supply stepdown DC chopper type single-stage multi-input independent power supply system is designed and developed.PSIM simulation and experimental results show that the proposed independent power supply system has single-stage power conversion,high-frequency galvanic isolation,high power density,high conversion efficiency,three power supply modes,high output voltage waveform quality and excellent performance,and has broad application prospects in the field of new energy combined power supply.