Research And Design Of Single-phase Grid-connected Photovoltaic Inverter

As the most widely distributed clean energy in the world,solar energy is widely used.More and more attention has been paid to the research of solar inverter control technology.In view of the low efficiency and poor stability of the traditional single-phase grid connected inverter,this paper improves the efficiency of the inverter by improving the maximum power point tracking algorithm of photovoltaic cell and using soft switching circuit and other technologies,in the meanwhile,the stability and reliability of the system was increased.In this paper,an improved dynamic impedance analysis algorithm is proposed based on the research of the current maximum power tracking algorithm,and the advantages of the improved algorithm are verified by simulation.In the aspect of hardware circuit structure,the boost circuit is designed to track the maximum power point of photovoltaic panel,the structure and driving characteristics of the former stage push-pull boost circuit and the later stage full bridge inverter circuit are analyzed.The control system uses 32-bit ARM processor as the main control chip and IR21064 as the driving circuit of high-power switch,at the same time,the flyback switching power supply with low switching loss and anti electromagnetic interference is designed to supply power for the control system.The paper designs and realizes the parameter detection of inverter and the protecting functions of voltage and temperature.In the aspect of control strategy,the realization principle of SPWM waveform based on STM32 is discussed,the loop control strategy based on AC side current sampling and the feed-forward control strategy of power grid voltage sampling are designed,and the implementation methods of phase-locked loop as well as input capture digital methods based on STM32 timer are analyzed in detail.NB-IOT communication mode is used to transmit the working parameters of the inverter to the cloud server,meanwhile,the upper computer monitoring interface based on LabVIEW software platform is designed to realize the remote monitoring function.Finally,the circuit and control algorithm are simulated in PSIM software,the simulation results show the reliability of the inverter.A single-phase grid connected photovoltaic inverter prototype is designed and manufactured,the experimental results show that the inverter meets the requirements of the design,the control strategy and design scheme are feasible and meet the actual needs basically.