A Single-phase Buck-Boost Pv Inverter Which CAN Suppress Leakage Current

Current-mode inverters do not require large electrolytic capacitors in parallel,and they have a boost function,so current-mode inverters are ideally suited for photovoltaic grid-connected systems.However,current-type inverters used in non-isolated photovoltaic systems may have leakage currents,and they often use larger DC-side energy storage inductors,resulting in lower power density of the inverter.In this paper,a single-phase buck-boost photovoltaic inverter with suppressed leakage current is studied as a research object,and its leakage current problem is studied in detail.And proposed two kinds of modulation methods that can reduce the DC side energy storage inductance to improve the power density of the inverter.This paper first introduced the working principle of a single-phase buck-boost photovoltaic inverter that can suppress leakage current,and proved that it can effectively suppress leakage current by analyzing the topology.Due to the traditional modulation method,the DC-side energy storage inductance value will be very large,which will increase the system’s volume and cost,and the system efficiency will be reduced.Therefore,two modulation methods for reducing the DC-side energy storage inductance are proposed in this paper:One is to improve on the basis of the traditional SPWM,called the nonlinear carrier-type modulation strategy.The other is to propose a new modulation method based on the topology,called a new modulation strategy.On the basis of the two modulation strategies proposed in this paper,the ability of buck-boost for the topology is studied separately and a mathematical model is established.Closed-loop simulation and grid-connected simulation are performed.The simulation results show that the inverter has a wide range of input voltage variation,and it has a good inhibitory effect on input voltage disturbance and load disturbance.On the basis of theoretical analysis and simulation,the software and hardware of the inverter were designed,experimental prototypes were set up,and experiments of open loop,closed loop and grid connection were conducted.The correctness of the theoretical analysis was proved through experiments.