Single-stage Single-phase High Voltage-gain Three-port Integrated Quasi-Z-source Inverter

Solar photovoltaic power generation had broad development prospects and inverter was an important part of photovoltaic power generation system.The quasi-Z source inverter overcame the inherent shortcomings of traditional voltage-type inverters,and had the advantages of simultaneously achieving step-up and invert,switches on bridge arms can be short-circuited,and had high waveform quality.However,the boosting capability of a quasi-Z source inverter was restricted by the modulation ratio,and it can't meet the output voltage demand in the case of a low input voltage.In addition,quasi-Z source inverters didn't have energy storage port and can't make full use of solar energy.Therefore,to improve the voltage gain of quasi-Z source inverter,reducing its volume and weight,and increasing the energy storage port are the research hotspot of quasi-Z source photovoltaic inverter,which had significant value on theory and engineering application.In order to improve the voltage gain,power density and energy storage function of quasi-Z-source inverter,a single-phase quasi-Z-source three port integrated inverter with magnetic integrated inductor and three ports of input source energy storage element load is proposed based on the discussion of quasi-Z-source inverter with high voltage gain.The key technologies,such as principle characteristics,high gain magnetic integrated impedance network,resonance network and main circuit parameters,were analyzed and simulated in depth,important conclusions were obtained.The topology of single-stage single-phase high gain quasi-Z-source three port integrated inverter and the energy management and control strategy of the master-slave power distribution of photovoltaic cells and batteries with the input DC voltage outer loop and the output voltage instantaneous value feedback inner loop of the photovoltaic cell MPPT were proposed and analyzed.The proposed circuit topology consist of an input filter capacitance,a magnetic integrated high-gain impedance network,a single-phase inverter bridge and a single-phase filter,and an energy storage element is connected at both ends of an energy storage capacitor of the high gain magnetic integrated impedance network.The energy management control strategy can control the size and direction of the battery power flow according to the relative size between the AC load power and the maximum input source power,and realized the stability of the system output voltage and the smooth and seamless switching of the three power supply modes.In this paper,the high frequency switching process,the expression of boost factor,the small signal model of the magnetic integrated impedance network,the resonance network,the flux and equivalent inductance of the magnetic integrated inductor and the current ripple of the single-stage single-phase high gain quasi-Z source three port integrated inverter are studied.The key circuit parameters such as the storage capacity,the design criteria magnetic integrated inductor,the output filter,the power switching voltage and the current stress are derived.A 1kVA 80-110 V DC/220V50 Hz AC single-stage single-phase high gain quasi-Z source three port photovoltaic integrated inverter was designed.The PSIM simulation results verified the feasibility and correctness of the proposed photovoltaic integrated inverter.The proposed single-stage single-phase high gain quasi-Z source three port photovoltaic integrated inverter had the advantages of three port including input source-energy storage element-load,three power supply modes,simple circuit structure,with high voltage gain,reliability,power density and output waveform quality,which provided an effective new method for low input voltage or wide range input voltage photovoltaic power generation system.