Design Of Single-phase Isolated Two-stage Miniature Photovoltaic Inverter

The world is facing an energy crisis,so it is imperative to find a new energy source to replace traditional energy sources.The advantages of solar energy are obvious to all.Solar energy is efficient and clean,and its resources are very rich.The micro-photovoltaic inverter uses photovoltaic power to convert solar energy into electric energy for people to use.This is a new way and has good development prospects.This paper designed a single-phase isolated two-stage micro photovoltaic inverter.The advantages and disadvantages of several topological circuits are analyzed and compared,and finally the main circuit structure of the micro-inverter is determined,and the two-stage structure of the front and rear stages is adopted.A push-pull circuit is used for the front-stage DC-DC boost converter,and a single-phase full-bridge circuit is used for the rear-stage DC-AC inverter converter.An output filter circuit is also designed to filter out high-frequency and harmonic components,and the control strategy of the micro-inverter is studied.The PWM switch in the front stage is used to control the switch and the SPWM control is used in the rear stage to determine the inverter 's Overall design plan.Next,the overall inverter was simulated and analyzed,and the maximum power point tracking technology(MPPT)was added.The variable step size disturbance observation method was used to further verify the correctness and feasibility of the overall design scheme.Select STM32F103ZET6 as the main control chip to design the control system of the micro-inverter.Its hardware design mainly includes the push-pull boost conversion circuit and high-frequency transformer in the DC-DC circuit,and the full-bridge inverter circuit and filter in the DC-AC circuit.The design of the circuit,the drive circuit of the front and back switch tubes in the peripheral circuit,the photovoltaic array detection circuit,the outputvoltage and current sampling circuit,and the auxiliary power supply.The software design includes the main control program of the conversion circuit,the MPPT algorithm program,the PWM program,the SPWM program,and finally the experimental platform is built.The experimental waveforms and data are tested and analyzed.The experimental results show that the expected results have been achieved.