Research On Control Strategy And System Design Of Photovoltaic Micro-inverter

Photovoltaic power is an important way for the use of new energy.As an important component of the equipment of the grid-connected photovoltaic micro-inverter,the control mode directly affects the efficiency of photovoltaic power generation system.the flyback-forward micro-grid-connected inverter is constructed whice based on the analysis of the micro-inverter topology,The active clamp circuit and the voltage doubler rectifier are studied as the output to improve the working efficiency of the circuit and the sliding mode variable structure.The theory of PWM control strategy to improve the robustness of the system,and the construction model of the simulation experiment validation.Finally,a 300 W micro grid inverter is proposed and designed.We give the hardware and software design and the actual operation test of the prototype.The results show that the system is effective and feasible.The main work of the paper is as follows:1.Based on the analysis of the structure topology of photovoltaic micro inverter,the micro-inverter with flyback-forward structure is studied.Through the analysis of the working process of the pre-stage DC-DC boost converter and the post-stage DC-AC grid-connected inverter,the method and control strategy of improving the working efficiency are also given.2.The circuit topology based on high-end active clamp circuit soft switching technology and converter output voltage doubling and rectification technology is studied,and the simulation results show that the method can effectively reduce the loss of MOS tube and improve the work effectiveness of converter.3.Aiming at the PWM drive control problem of DC-DC converter,a PWM control strategy based on sliding mode variable structure theory is proposed.By constructing the switching function between the output voltage and input current,the output ripple is reduced and robustness of the system is improved.The simulation results show the effectiveness of the proposed method.4.A design prototype of 300 W grid-connected micro-inverter is designed and completed.The circuit design and parameter calculation of the main circuit and the control circuit based on DSP33035 are given and the corresponding control software flow chart is given.The experimental results show that the method is correct.