Research On Non-isolated Single Phase Photovoltaic Grid-connected Inverter And Its Suppression Of Common Mode Current

With the growing global energy crisis and environmental pollution,the development and utilization of clean and renewable energy is imperative.As renewable energy,solar energy has received extensive attention,because it is not only green,but also widely distributed.Photovoltaic grid connected power generation is an important way to use solar energy,and the core of grid connected photovoltaic power generation system is photovoltaic grid connected inverter,whose efficiency affects the efficiency of the whole system.Non-isolated grid connected photovoltaic inverter has the advantages of small volume,high efficiency,low cost and favored by people,but the common mode leakage current is a potential threat to people and equipment.In view of the limitations of non-isolated single phase grid connected inverter and its suppression of common mode current,this paper makes a deep research and design:Firstly,the operating principle of isolated and non-isolated grid connected inverter is analyzed,and their advantages and disadvantages are compared.Secondly,this article analyzes the principle of the common mode current of the non-isolated grid connected inverter,and the influence of the distributed capacitance on the common mode current.The method of suppressing the common mode current is studied from the aspects of changing the modulation mode and changing the topology structure based on the inverter topology and PWM modulation strategy.Then verify the effectiveness of suppressing method the common mode current By building a MATLAB simulation platform.Thirdly,the control strategy of photovoltaic grid connected system is analyzed.The front step boost circuit adopting the variable step perturbation method to achieve the maximum power point tracking(MPPT)effect,which solves the problem of oscillation and misjudgment of the fixed step perturbation method.In the meantime,the double inverter control strategy is used to stabilize the DC side voltage of the inverter.The feasibility of the control strategy is verified on the MATLAB platform.Finally,on the basis of theoretical analysis and simulation,the hardware and software design of the system is carried out,and the DSP2812 is used as the control center.The experimental results are in good agreement with the simulation results,which verifies the feasibility of the system design and the effectiveness of the common mode current suppression method.