Research On Switch-inductor Quasi-Z-source Network Of The Photovoltaic Inverter System

Energy crisis and serious environmental pollution has gradually affected economic construction and development of the country, also give people’s living standards and physical health bring irreversible serious consequences. Therefore, the development and utilization of new energy resources are incorporated into the national development strategy plans. Specially, photovoltaic power generation industry, as the most representative, is considered as a pillar of the new energy industry in the future because of its economic, clean, non-polluting and sustainable, and it has received a high degree of attention and focus. In this paper, we mainly have made an in-depth research on the inverter topology of photovoltaic power generation, the design of the system structure and the control strategy.Analysis and research boost mechanism of switch inductor structure, switch-inductor quasi-Z source inverter topology structure is proposed, and analysis the working principle of its shoot-through mode and non shoot-through mode in detail, derive the topological structure parameter equation, compared with the traditional Z-source network topology, the result shows that it can arise the boost ability and make the voltage and current stress of both capacitor and switch element decreased. Combined with the performance requirements, the parameters of the system components are determined, and the hardware circuit is designed.Build the equivalent circuit model of PV array, analysis and research the effect of solar irradiance temperature and light intensity on the output characteristics of PV array, the result shows that PV array output voltage changes slowly in the allowable load capacity. Comparing with the advantages and disadvantages of several typical dc link voltage control strategies, the PV array output voltage feedforward dc link voltage control strategy is proposed, the proposed control strategy not only can track and adjust the dc link voltage in real time, but also can make the voltage and current stress of switch elements reduced. the output filter circuit is optimized and designed, the double closed loop control strategy is adopted, including voltage loop control and current loop control, and the controller is designed by pole assignment of state space.Using MATLAB/Simulink software to build the simulation model of photovoltaic power generation inverter control system, and analysis the results of simulation, the software block diagram of system is designed, to write the corresponding program code according to the main program and the flow chart of the subroutine, the corresponding hardware platform is built. Combined with hardware and software, the system for the on-line debugging and testing, results of simulation and experiments validate the feasibility of switch-inductor quasi-Z source network topology and correctness of the control strategy, to ensure stable and reliable operation of the system and quality of inverter output power.