Abstract: Three-level neutral-point balance method based on PWM pulse width dynamic regulation was

proposed to realize optimized PWM high-performance closed-loop control and three-level neutral-point balance

control of the inverter at low switching frequency. The fundamental current component was extracted from the

current observer，and the dynamic regulation time and steady-state regulation voltage were calculated to avoid the

regulation time swing caused by the participation of current ripple sampling in regulation.By modifying the edge of

each phase PWM independently，there is no coupling among the correction of three-phase PWM pulse width.So the proposed method breaks through the limitation of using common mode component to regulate neutral-point balance in conventional method，which is suitable for specific harmonic elimination（SHE）modulation and other occasions where the switching angle needs to be optimized by looking up tables to realize synchronous modulation.

      Key words: three-level；current observer；neutral-point balance