Research Of Photovoltaic Grid-connected Inverter For PV Non-Isolated Based On The H6Topology

With the increasing development of photovoltaic technology, the use of solar energy to electricity area gradually from no development areas have electricity, many countries have introduced a photovoltaic power generation projects. At present, China in this regard, mainly in terms of large-scale power plants in the home-roof photovoltaic applications is still relatively small. From the point of view of global trends, miniaturization, intelligence and modularity will be the next major development of photovoltaic grid-connected inverter trend. In grid-connected PV system, the inverter to achieve the solar panels generate DC power into the grid with the same frequency and phase of the AC power and fed into the grid, photovoltaic grid inverters are grid-connected PV systems hub unit. Different applications can choose different grid inverter, research paper is distributed photovoltaic systems, mainly for non-isolated single-phase photovoltaic grid inverters research.Firstly, this paper summarizes the development situation at home and abroad and research status quo of photovoltaic (pv) grid power generation, to give a brief introduction of photovoltaic (pv) grid power generation systems. Secondly, on the model of the single-phase grid inverter, the mechanism of common-mode current are analyzed, leakage current of different topologies have been different PWM modulation strategy produced under the conditions. In summing up the basis of different topologies can suppress the common mode leakage current, proposed a kind of common mode leakage current has good inhibition and high efficient H6bridge inverter topology. On this basis, given the overall design of a two-phase non-isolated single PV inverter.Then, the study’s photovoltaic inverter control strategy in detail. Based on the summary of the current commonly used maximum power point tracking control strategy, proposed a momentary power disturbance observer detection method based on variable step-type MPP control strategy. Since PV grid inverter DC input voltage fluctuation exists, the inverter bridge wall requires deadband control and grid instability issues, leading to the current grid inverter incorporated into existence waveform distortion, power quality decline and other issues, therefore, the current control based on grid voltage feed-forward double closed loop PI control scheme. Front part of the grid voltage feed-forward power to eliminate the interference, the use of double-loop PI control method for improving the dynamic characteristics of the inverter.Finally, the use of simulation software Matlab/simulink, designed for grid-connected PV systems theoretical simulation,, simulation results show that the design is correct, reasonable. In the laboratory, the trial of a2KW photovoltaic grid inverters experimental prototype, analyze the hardware circuit and DSP chip-based system control software, experimental verification is reasonable design.