Research On Photovoltaic Grid-connected Micro Inverter

As a pollution-free renewable energy, Solar energy has become a new energy field and tapinto the hot around the world with today’s energy increasingly tense. Photovoltaic grid inverter asthe core of the photovoltaic power generation system, is going forward to the high efficiency,high reliability, high power density and low cost. And micro inverter which can overcome thetraditional centralized photovoltaic power generation system in local maximum power trackingproblem when in the shadow, is become the focus of research in recent years. this paper Basedon the micro photovoltaic grid inverter as the research object, held several key technicalproblems, and made the hardware principle and control strategy analyzed in detail, at lastdeveloped a crisscross flyback photovoltaic grid micro inverter.First, This paper studied the output characteristic of photovoltaic array in the partial shadow,and points out the limitations of the traditional centralized photovoltaic inverter, whilehighlighting the micro inverter’s advantage of making full use of solar energy resources in themost power tracing and preventing the hot spot phenomenon. Secondly, summarized the the twokinds most widely used topology in the field of currently micro inverter, and analyzed itsworking principle in detail, principle of in-grid, and compared the advantages and disadvantages.after compromising chose the active clamping interleaving flyback topology; Again, according tothe requirement of the micro inverter efficiency, this paper analyzed the flyback inverter loss ofeach part, using the soft switch technology to reduce the loss of power component switchingelements and realized the leakage inductance energy recycling; In addition, in order to overcomethe life of the electrolytic capacitor problem, this article embarks from the power decouplingprinciple, according to two kinds of views decoupling circuits, made a detailed analysis andcomparison, and made a simulation analysis on one of them, proved the feas ibility of decouplingcircuit.In the aspect of control strategy, this paper concretely introduces the flyback of two kinds ofworking mode, through the analysis of their advantages and disadvantages, adopted a DCM andBCM hybrid control mode, namely, simplifies the control loop and improve the quality of thegrid waveform. In MPPT control strategy, with the need of micro inverter and low cost, thispaper adopted single of current sensor which called incremental conductance method, eliminating the current sensor, and saving the cost and reduce the volume of the inverter; In viewof the distributed parallel standard strict requirements, this paper established the grid currentDCM flyback model, and using the MATLAB simulation giving the results.Finally, on the basis of the analysis and simulation, set up a230w solar micro inverterexperimental platform, and had realized the basic functions, verified the feasibility of thetheoretical analysis. And according to the experimental results, put forward some pract ical andfeasible optimization designs.