Current Harmonics Analysis And Suppression For H6 Topology Based PV Inverter

Photovoltaic power generation is the most promising energy in the renewable energy.The small and medium power distributed photovoltaic power generation is the trend of the future.The inverter is the core of the photovoltaic power generation system.The Single-phase photovoltaic inverter system based on H6 topology has the small common-mode leakage current,the small current distortion and the high security.The photovoltaic inverter based on H6 has a good application prospects in the photovoltaic power generation industry and good application prospects.The power grid harmonics have a great influence on the current quality of the inverter.The current harmonics of the Inverter has a great influence on the power grid and other electrical equipment.The harmonic current based on H6 bridge photovoltaic inverter is more complicated.There's great meaning to improve the harmonics suppression characteristics of photovoltaic inverter of H6 topology to improve the performance of the inverter and its adaptability to the power Grid.The quasi-proportional resonance + repetitive control of the current loop,and voltage loop control with the Notch filter to suppress current harmonics are proposed.The main research contents are as follows:The paper summarized the research of single-phase non-isolated inverter and the harmonics suppression technology of photovoltaic inverter of H6 topology.The structure,working principle and the mechanism of leakage current suppression of H6 topology is analyzed.The mathematic model of the double closed loop control system is established for the inverter.The limitation of the traditional PR control for H6 bridge inverter is analyzed.The PR + RC control of the current loop,and voltage loop control with the Notch filter to suppress current harmonics is proposed and the parameter design method is given.The stability of the designed control system is verified.The 10 kW photovoltaic inverter based on H6 topology is build.Experiments were carried out on the PQR + RC controller and the voltage controller with a notch filter.The results show that the THD of the output current is 2.273% under the proposed harmonics suppression strategy,The THD of the output current under the conventional PQR control strategy is 2.977%.The proposed PR + RC control of the current loop,and voltage loop control with the Notch filter to suppress current harmonics has a good power quality.for the photovoltaic inverter.