A Single Phase Multilevel Inverter with Novel Capacitor Voltage Balancing Technique

For medium-voltage power electronic applications, multilevel converters have become a popular option. While conventional twolevel converters utilize a direct series connection of switches to meet medium-voltage requirements, multilevel converters allow a higher voltage handling capability with reduced harmonic distortion and lower switching power losses. One of the most important requirements in the operation of multilevel converters is balancing capacitors voltages. They define all levels of the converter output voltage. However, the voltage across the capacitor may grow or decay so that the neutral point voltage fails to keep the half of the DC link voltage. They have a direct impact on the operation of the converters, as their variations are found on the voltages applied to the switching cells. This imbalanced condition needing higher rated capacitors and also can causes failure of the power semiconductors. The capacitors voltages must be equitably distributed to ensure a balanced distribution of the constraints in power switches voltage. This paper proposes a novel capacitor voltage balancing technique for multilevel inverter.