Design And Realization Of T-level Photovoltaic Grid-connected Inverter Based On TMS320F28335

As the fossil resources storage increasingly decrease,mankind has focused on the exploitation of renewable energy,among which the photovoltaic(PV)generation is developing rapidly.At present,the three-level inverter has been widely used in PV generation field.Especially,the T-type three-level inverter is more promising compared with other three-level inverter topologies,so the paper selects the T-type as the research object.This paper,whose topic is mainly based on engineering practices,places emphasis on the rationality and implementation methods of the design.Firstly,the paper introduces the context of grid-connected photovoltaic system,three-level inverter’s topologies and relevant key technologies after collecting researches that are from previous researchers and practitioners,and points out the research subject.Then,the paper explains the working principle and mathematic model of photovoltaic cell,and then puts forward the MPPT control strategy used in this paper,which is a group control strategy controlling the multiplex paralleled MPPT.By this way,the whole system’s generation efficiency is further increased.Also,the control structure and principle of grid-connected PV inverter are analyzed.Next,the operation principle and current change method of T-type three-level inverter are elaborated,and then the paper introduces the space vector pulse width modulation(SVPWM)strategy.The advantages and disadvantages of different neutral point voltage balance algorithms applied in SVPWM control strategy are compared.The harmonics of conventional three-level inverter with SVPWM control strategy under low switching frequency is excessive,and to tackle this problem,an original three-level natural sampling SVPWM(NS-SVM)algorithm which combines natural sampling algorithm and SVPWM strategy is proposed.Then,the NS-SVM is simplified using the Newton-Raphson iterative method,making the NS-SVM achieve fast online digital implementation.Finally,based on the above theoretical analysis,the hardware and software to test the designed T-type three-level inverter are designed,and the MATLAB simulation model and prototype experiment platform based on TMS320F28335 are built.The simulation and experiment results verify the feasibility of the designed T-type three-level grid-connected inverter.I hope this paper could provide theoretical and practical bases for the development of high-power T-type grid connected inverter in the future.