Aimed at the neutral-point unbalance problem of Neutral-point Clamped (NPC) Three-level inverter,this paper proposed a hybrid neutral-point balance strategy under space vector pulse width modulation(SVPWM).Under low modulation index,thirteen-vector modulation was used to gain relatively batter neutral-point balance effect.This method employed 1 zero vector,6 medium vectors and 6 large vectors to synthesize the reference vector.Under high modulation index,a method which modified the traditional seven-stage centered modulation was adapted.It could minimize the fluctuation of neutral-point potential by adjusting the function time of positive or negative small vectors.Quasi-PR controller was adapted to track the command current.The parameters was chosen according to optimal theory of second-order system.At last,a simulation model was established in MATLAB/simulink to verify the middle point balancing strategy and quasi-PR control.
