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

Compared with traditional PWM inverter,quasi-z-source inverter has the advantages of single-stage power conversion,voltage rise and fall,inverter bridge can be directly connected to open circuit,inverter bridge switch does not need to set dead zone and output waveform is high quality.However,due to the limitation of modulation ratio,the boost factor of quasi-z-source inverter has some defects,such as high power switching voltage stress,high voltage stress of energy storage capacitor and poor quality of output waveform.Therefore,to improve the voltage gain,reduce the volume and weight of quasi-z-source inverter,and improve the stability and continuity of power supply is the research hotspot of new energy quasi-z-source inverter,which has important theoretical value and engineering application value.In order to further improve the voltage gain,conversion efficiency and system reliability of quasi-z-source inverter,based on the theoretical analysis of quasi-z-source inverter with high gain,this paper proposes a single-stage three-phase high gain quasi-z-source three port integrated inverter.In addition,the key technologies such as circuit topology,energy management control strategy,principle characteristics,high gain magnetic integrated impedance network and main circuit parameters of the inverter are analyzed and simulated,and important conclusions are obtained.This paper presents and analyzes the circuit topology of single-stage three-phase high-gain quasi-z source three-port integrated inverter,which is composed of an input filter capacitor,a high gain magnetically integrated impedance network with energy storage elements connected to the storage capacitor,a composite active clamp circuit,a three-phase inverter bridge and an LC output filter.The improved SVPWM control strategy of photovoltaic and accumulator master-slave power distribution energy management with MPPT voltage outer loop,output voltage effective value feedback and energy storage capacitor voltage feedback inner loop of single-stage three-phase high-gain quasi-z source three-port integrated inverter is proposed and analyzed.According to the relative size of the ac load power and the maximum power of the input source,the power flow size and direction of the battery charging and discharging switch are controlled in real time.Further study of the single-stage three-phase high-gain quasi-z source three-port integrated inverter process of high frequency switch integrated inductance,magnetic ac/dc magnetic flux change rule under different number of turns and reluctance expression as well as the relationship between the equivalent inductance and ripple,high-gain magnetic integration impedance network has been set up small signal model,deduced the magnetic integrated energy storage capacitor,inductor,composite active clamp circuit and output filter.3kVA 80-110VDC/380V50 Hz ac single-stage three-phase high gain Quasi-Z source three port integrated inverter is designed and tested in the PSIM simulation software.The simulation results verify the correctness and feasibility of the proposed integrated inverter.It has the advantages of single-stage power conversion,simple circuit structure,three power supply modes,high voltage gain,high reliability,high power density and high output waveform quality.It provides an effective new method for low input voltage or wide range input voltage new energy generation system.