Single-stage Three-phase High-gain Quasi-Z Source Three-port Photovoltaic Independent Power Supply Syste

Photovoltaic independent power supply system has the features of unlimited time/geographical conditions,reduced size,and low cost.Thus,photovoltaic independent power supply system is more desirable for mobile lighting/charger equipment,outdoor emergency power supply,and remote power generation,etc.In particular,the single-stage photovoltaic independent power supply system with strong voltage boost capability,which is one of the hottest topics in the field of photovoltaic power generation,can overcome the defects of cascade instability of two-stage system and the shortcomings of poor tracking effect and low efficiency of MPPT of photovoltaic module series voltage boost scheme.In general,impedance-source inverter has the features of wide output voltage regulation range,no inverter bridge arm shootthrough fault,and high output waveform quality,which can overcome the inherent defects of traditional PWM inverter.However,the existing impedance-source inverter has the disadvantages of numerous passive components and hard switching operation of power devices,which limits the further optimization of cost,size,and conversion efficiency of the whole system.Therefore,improving voltage gain,efficiency,and power supply stability,reducing volume and weight are the research hotspots of impedance-network converter,which has vital theoretical and engineering application value.A novel single-stage three-phase high voltage gain quasi-Z source three-port photovoltaic independent power supply system is proposed in this paper.The circuit configuration,modulation strategy,control strategy,working mode,steady-state characteristics,parameter design,loss analysis,and efficiency calculation are discussed in detail.Comprehensive simulation analysis and experimental research are carried out,and valuable conclusions are provided.The proposed three-phase high voltage gain quasi-Z-source three-port photovoltaic independent power supply system is composed of input filter,battery-assisted high voltage gain networks,active clamping auxiliary units,three-phase inverter bridges,and output filters which are cascaded sequentially;The battery port is connected in parallel with the high-gain network capacitor,and the three high-gain network inductors are wound on the same UIU core through magnetic integration strategy,reducing the volume of the whole system.A 12-sector partition improved SVM maximum power output energy management control scheme with instantaneous value feedback of output voltage and output current is adopted.The six sectors of the traditional SVM modulation strategy are further divided into twelve sectors based on the polarity of the instantaneous value of the output phase current.In each highfrequency switching cycle,the inverter bridge shoot-through zero vector is concentrated;The proposed improved 12-sector partition SVM control strategy based on the instantaneous value feedback of output voltage and output current separately controls the shoot-through duty cycle 0and modulation M,so as to realizes MPPT and the control of output voltage and output power.The power supply system has three modes: single input and double output,double input and single output,and single input and single output;The expression of voltage gain and the key parameters design criteria such as energy storage element,device voltage and current stress,realization condition of zero voltage switch,configuration of energy storage port,input filter,and output filter are deduced.Then,the loss analysis is performed.Finally,a 1k VA 96-186VDC/220V50 Hz AC principle prototype is designed and developed.The simulation results and prototype experimental results show that the proposed system has the advantages of simple structure,high voltage gain,power device ZVS operation,high power density,and high efficiency.The proposed system provides a promising application prospect in photovoltaic power supply system with low input voltage or wide input voltage variation.