The Study Of Grid-connected Photovoltaic Micro-inverter Related Technologies And Efficiency Based On DSC

According to uses,Grid connected photovoltaic micro inverter can be divided into three types: centralized,distributed and self-supply.Among them,distributed inverter,which is also called the micro inverter,is now the mainstream research of the photovoltaic inverter,because of its advantages of flexible,easy to collection and cover.The main task of this paper is to analyze,modify,optimize and innovate the main technical problems,circuits,algorithms and mathematical theory formulas in the design process of the grid connected photovoltaic micro inverter.So as to improve the inverter performance and efficiency of the whole machine.Based on the study and research of grid connected micro inverter,classification the structure of the solar inverter system,subdivision the hard circuit design and the algorithm implementation of the various parts of the structure,and completion the prototype of rated capacity 300 VA grid connected photovoltaic micro inverter.In the view of problems,such as the leak inductance energy absorption and reuse,the maximum power point tracking(MPPT),the voltage spike suppression,the soft-switch,the inverter stable output,the half wave phase shift and the full wave zero drop,existing in the design of grid connected micro inverter,this paper mainly completed the following contents:(1)Presented a new circuit type of RCD leak inductance energy feedback and voltage suppression.The new type can reduce the distortion,energy consumption of the half wave of the inverter,improve the working performance of the whole machine,and provide better single input for the subsequent inverter stage.(2)Presented a method of MPPT control based on power varibale step-size,combining the advantages of the constant-voltage method,the perturb-observe(P&O)method,and the traditional variable step conductance increment method,in photovoltaic converter system.The new method improved the MPPT algorithm efficiency and the energy utilization efficiency,optimized the performance of the whole machine,and provided stable and efficient power input for the subsequent inverter stage.(3)Presented a control strategy of depressing the voltage spike during soft-switch based on the method of PI in photovoltaic converter system.The new control strategy can improve the safety coefficient of engineering,reduce the energy consumption,and inhibit the voltagespikes.The strategy can complete repair the hot and howling phenomenon during the heating frequency MOSFET operation,and improve energy utilization efficiency.(4)Presented a synchronization control strategy based on silicon controlled H bridge combined with external interrupt algorithm.The new synchronization control strategy can modify the defect of traditional H bridge inverter circuit,combine the hardware circuit and the software algorithm to correct the half wave phase shift,and reduce the distortion of the whole wave to output the power frequency sine wave.(5)Presented the stable output of the inverter,which will provides the necessary conditions for the subsequent inverter efficiency test.(6)Construction the hardware circuit,with the visualization software,can real-time testing the performance and efficiency of the optimized inverter.Realized the grid function,so that the normal working of electrical equipment network.In this paper,the designed solar inverter can input 30V~50V DC voltage,and output inverter AC voltage 230 V 50HZ,the inverter efficiency reached 96.2%~97.6%.