Carrier Based Neutral Point Potential Regulator With Reduced Switching Losses For Diode Clamped Multilevel Inverter

摘要

Neutral Point Clamped converter, also called as three level Diode Clamped Multilevel Inverter (DCMLI) offers several advantages such as lower voltage stresses, lower electromagnetic compatibility and better output. However, there is an important problem called Neutral Point Voltage (NPV) variation which leads to voltage unbalancing across a DC link and output waveform of the inverter. This variation happens due to the non-line arities in the circuit, nonlinear loads, load unbalancing and nonuniform distribution of charges. In this paper, an NPV balancing strategy for Neutral Point Clamped (NPC) multilevel inverter is proposed and it is based on the Sinusoidal Pulse Width Modulation (SPWM). In this technique, an offset value gets added to modulation wave to balance the NPV and its performance is also analyzed based on its THD and efficiency. It is also found that the reduction in switching losses is achieved when compared to conventional inverter.