Research On Non-leakage Current Boost DC/AC Photovoltaic Inverter

With the increasingly urgent global energy situation,solar energy has become popular due to its abundant resources,clean and pollution-free characteristics.With the further development of relevant technologies in the solar power generation industry,driven by the implementation of carbon peaking and carbon neutralization policies in China,global photovoltaic power generation ushers in new opportunities.Among them,as the key interface equipment of photovoltaic power generation systems,photovoltaic grid connected inverter are favored by users and integrators.Therefore,the research on high-performance photovoltaic grid connected inverter with high power conversion efficiency,simple structure,low cost and strong flexibility has theoretical significance and application value.This paper focuses on the transformer free photovoltaic grid connected inverter.The common mode leakage current in the system is analyzed,and the principle of restraining common mode leakage current with different single-stage inverter structures is studied.Considering the low-voltage output characteristics of a single photovoltaic cell,the conventional photovoltaic power generation system is usually a two-stage circuit,that is,the front stage uses the DC/DC boost circuit to increase the voltage input to the photovoltaic cell,and then uses the full bridge inverter to control the inverter and network current.However,the structure of the two-stage boost inverter not only increases the complexity of the circuit,but also increases the system loss,It also increases the cost of the system.To solve the above problems,this paper proposes two single-phase single-stage step-up photovoltaic Inverters without leakage current.Both topologies can not only complete the step-up inverter function,but also suppress the generation of leakage current from the structure itself and improve the reliability of the system.This paper analyzes the working principle and steady-state characteristics of the bill of lading step-up DC/AC converter in detail,and gives several inverter topologies.The corresponding SPWM modulation modes are given for the two inverter topologies,comparing and analyzing to summarize the characteristics of each modulation mode.Then,based on the PI controller and PR controller commonly used in engineering,the QPR controller is designed.Next,the maximum power point tracking technology and QPR control are combined to the inverter proposed in this paper,and a small photovoltaic grid connected inverter system is constructed.The feasibility of the proposed inverter and control method is verified by Matlab / Simulink simulation platform.Finally,the hardware design of the proposed topologies main circuits are given on the basis of principle analysis.The parameter design of power devices and boost inductors,bus capacitors are being considered.Last but not least,TMS320F2812 as the core control has been used to built an experimental prototype.The experimenty verified the feasibility of proposed inverter and the previous theoretical analysis is proved to be correct.