Neutral point potential balance is an important problem in design of three-level inverter

the imbalance of neutral point potential not only increases voltage stress of power device

but also results in inversion failure in the active inversion situation.In this paper

a mathematical model of three-level inverter is presented

and the theory of the space-vector pulse-width modulation method and the causes of neutral point potential imbalance are analyzed.Then a neural point potential balance method based on space-vector switching technology is proposed

in which the revision of the current PWM signal is completed through small voltage vector equivalent switching according to the measurement of voltage and AC current of two capacitors

leading to the neutral point potential balance.Simulation results verify the feasibility of the proposed method.