Research On H10 Three-phase Inverter Leakage Current Suppression Technology

In the context of the extreme shortage of fossil energy,the development of the new energy industry has been greatly improved.Compared with traditional power generation,the most widely used and simplest form of new energy power generation is solar photovoltaic power generation.Due to the isolation transformer in the traditional photovoltaic inverter,the volume and weight of the system are high and the efficiency is low.Therefore,non-isolated photovoltaic inverters are sought after at home and abroad.However,due to the lack of isolation transformers,a large amount of leakage current exists in photovoltaic power generation systems.High leakage current can damage power generation equipment and endanger the personal safety of workers.Therefore,how to reduce the leakage current in photovoltaic systems is a major focus to be solved at present.In order to better solve the problem of leakage current in photovoltaic systems,the paper first reads a lot of literature on suppressing leakage current of non-isolated inverters,and understands that the common method used to suppress leakage current at home and abroad is to improve circuit topology or control strategies.Therefore,the idea of improving the non-isolated inverter topology to suppress the leakage current is proposed.Then start from the traditional three-phase non-isolated photovoltaic inverter,analyze the working state,establish the leakage current model of the photovoltaic system,analyze the cause of the leakage current,and mathematically deduce the factors that affect the leakage current.The mode voltage amplitude and the method of increasing the impedance of the common mode loop can reduce the leakage current in the system,and forward and reverse clamping H10 three-phase inverters are proposed.In both inverter topologies,isolating switches are added symmetrically at the positive and negative DC buses of a conventional three-phase inverter and three equivalent clamping capacitors are added at the DC side.The 1/3potential point is connected to the source of the lower arm switch tube,and the 2/3 potential point is connected to the drain of the upper arm switch tube,thereby clamping the common mode voltage in the freewheeling state to 1 of the DC input voltage / 3 or 2/3.By analyzing the amplitude of the common mode voltage and the magnitude of the leakage current,it is found that the reverse-clamped H10 three-phase inverter of the two new inverters has a better effect in suppressing the system leakage current.Simulation of the traditional three-phase non-isolated inverter and two new inverters under SPWM control proves the correctness of its theoretical analysis.Finally,according to the schematic diagram of the main circuit and the control circuit,draw a PCB circuitboard,solder the hardware circuit,build a 600 W experimental platform for hardware experiments,compare the experimental results of leakage current with theoretical analysis and simulation results,and verify the proposed positive and negative clamps.The feasibility of H10 three-phase non-isolated photovoltaic inverter in suppressing leakage current and further concluded that reverse clamping H10 three-phase inverter is more effective in suppressing leakage current.