The Design Of Variable Frequency Soft Switching Photovoltaic Grid-tied Inverter Based On FPGA

Oil,coal,natural gas and so on the disposable energy is the main energy in the people's life,but their capacity is limited and the use is not decrease,so according to the present using speed they will soon dry up;In addition,the traditional energy combustion after atmospheric pollution,cause serious influence on people's environment.The problems in reality are warning people that developing renewable clean energy to replace the traditional energy is very necessary.Clean energy such as solar energy,wind energy,geothermal energy,biomass energy.Especially solar energy,inexhaustible and widely distributed,is easy to use.Photovoltaic power generation system is to convert solar energy into electricity,occupies an important position in the use of solar energy,and the inverter is the core component of photovoltaic power generation system.It converts direct current(DC)into alternating current(AC)for people to use.Photovoltaic inverter has off-grid type and grid-tied type,especially the usage of grid-tied inverter is the biggest.So high performance of photovoltaic(pv)grid-tied inverter can improve the utilization of solar energy and photovoltaic power generation system stability,security,and people have been research hot spots.For photovoltaic(pv)grid-tied inverter,the DC-AC power conversion unit directly determines the overall performance of the inverter.This paper analyzes the current power transformation unit related circuit,and put forward the BuckBoost circuit based on the minimum Peak Current BCM control scheme(mPCBCM),BuckBoost circuit is studied in detail the current critical continuous mode(BCM)related to the control theory,and the correctness of the theory is verified by matlab simulation.This article proposed mPCBCM control scheme which needs real-time computing of current switching period for adaptive frequency conversion control.So a circuit can timely response,fast calculate the related parameters is needed to guarantee the output grid current has a smaller THD.As a result,more resources and faster processing speed of FPGA is used as the main control chip.At last,a prototype is designed and constructed,which completes the relevant DC and AC transformation test,further verifided the feasibility of the theory.Experiments show that the proposed mPCBCM control scheme implements all the switches zero voltage switch,which contributes to reduce the electromagnetic interference,improve the conversion efficiency,reduce the power inductors.