Ui-Min Choi, Hyun-Hee Lee, and Kyo-Beum Lee, “Simple Neutral-Point Voltage Control for Three-Level Inverters Using a Discontinuous Pulse Width Modulation,” IEEE Transactions on Energy Conversion, vol. 28, no. 2, pp. 434–443, Jun. 2013. -SCI > Paper

This paper proposes a neutral-point voltage balancing method for a three-level inverter that uses discontinuous pulse width

modulation (DPWM). The performance of a three-level inverter system is affected by the neutral-point voltage unbalancing. Therefore,

the voltages of series connected dc-link capacitors should be equal. Generally, the offset voltage is added to reference voltages in

the conventional voltage balancing method. However, when using DPWM, the performance of conventional balancing method is

limitary because turn-on and turn-off switching occurs at regular intervals. The proposed method is implemented by adjusting the

discontinuous pulsewidth of positive and negative cycle. The proposed method maintains low switching losses and achieves the

effective voltage balancing, without additional hardware and complex calculations. Simulation and experimental results confirm the

feasibility and effectiveness of the proposed method.