三电平逆变器中点电位偏移机理分析与平衡方法研究OA北大核心

Aimed at the problem of neutral-point potential balance control of three-level neutral-point clamped inverters,the cause of neutral-point fluctuation of a T-type three-level inverter was analyzed.Based on the non-harmonic injection and dynamic harmonic injection methods,the period Fourier series of the third-order harmonic of neutral-point current was derived and analyzed.First,an open-loop harmonic injection algorithm was derived,and a closed-loop harmonic injection algorithm based on proportional-resonance controller was proposed accordingly to suppress the neural-point current.Then,MATLAB/Simulink simulation software was used to simulate the open-loop harmonic injection and closed-loop harmonic injection algorithms,and a 40 kW three-level inverter was built for experimental verification.Both the simulation and experimental results can verify the correctness of theoretical analysis and the effectiveness of the proposed control strategy.