June-Seok Lee, Seungjong Yoo, and Kyo-Beum Lee, "Novel Discontinuous PWM Method of a Three-Level Inverter for Neutral-Point Voltage Ripple Reduction," IEEE Transactions on Industrial Electronics, vol. 63, no. 6, pp. 3344–3354, Jun. 2016. -SCI > Paper

A new pulsewidth modulation (PWM) strategy which is an alternative approach of the discontinuous PWM (DPWM) for a three-

level neutral-point-clamped (NPC) inverter is proposed in this paper. A three-level NPC inverter is completely mature and very well-

established topology in high-power applications. However, the three-level NPC inverter has an inheritance problem of the neutral-

point voltage unbalancing due to the split dc-link capacitors. This structure can cause large neutral-point voltage ripple. Furthermore,

output currents of the three-level NPC inverter are distorted by the neutral-point voltage ripple. Therefore, the neutral-point voltage

must be controlled. In this paper, a new DPWM method using two different offsets for the neutral-point ripple reduction is proposed

and the effectiveness of the proposed DPWM method is verified by using the simulation and the experimental results.