*Article* **Modulation Strategy with a Minimal Number of Commutations for a Five-Level H-Bridge NPC Inverter**

#### **Florent Becker 1, Ehsan Jamshidpour 2, Philippe Poure 3,\* and Shahrokh Saadate 4**


Received: 13 February 2019; Accepted: 18 April 2019; Published: 23 April 2019

**Abstract:** In this paper, a so-called OPTimized Pulse Width Modulation (OPT-PWM) strategy with a minimal number of commutations for a multilevel converter (MC) is proposed. The principle is based on the reduction of the number of switch commutations by removing the unnecessary ones for each voltage level transition. The OPT-PWM strategy is applied to a five-level H-Bridge Neutral Point Clamped (HB-5L-NPC) inverter. A specific block based on a state machine is added to conventional modulation techniques to perform the transitions from a given voltage level to another one via the best trajectory with a minimal number of commutations. The principle of this additional block can be applied to any modulation technique. In this paper, the proposed strategy is validated first by simulation and then through experimental tests.

**Keywords:** multilevel inverter; Pulse Width Modulation; minimal number of commutations; state machine; Neutral Point Clamped Converter
