A New Step-up Voltage Balancing Circuit for Neutral-Point-Clamped Multilevel Inverter

This paper introduces a new voltage balancing circuit for Neutral-Point-Clamped (NPC) Multilevel Inverter (MLI). The proposed circuit consists of switched-capacitors network which can easily balance the NPC-MLI by using proper switching state in carrier-based Pulse Width Modulation (CB-PWM) technique. This new voltage balancing network is readily extendable for using at higher-levels (e.g. 4, 5, 6 ...)that facilitate the balancing problem in NPC-MLIs. Moreover, one of the most important features of the proposed balancing network is that it uses only one DC source at the input and can increase the input dc voltage to a higher level at the output without using any magnetic elements. This let the converter operate with the capability of boosting the input at the required output voltage with the ability of self-balancing. The simulation by using MATLAB/Simpower System and experiment set up of the proposed system has been conducted for three-phase four-level NPC-MLI which confirm the ability of the proposed circuit to balance the capacitor voltages properly.