A three-level MOSFET inverter for low power drives

This paper proposes operating a three-level neutral point clamped (NPC) inverter using a two-level PWM method. This allows for the clamping diodes to be rated at a fraction of the main switches due to their low average current requirement. The use of a charge pump as a low cost method to obtain the isolated gate drive power supplies is extended for use with the NPC topology. Using this control method and circuits, an inverter based on high volume, low-cost, low-voltage power MOSFETs is experimentally demonstrated as a possible economic alternative to an IGBT based drive for 120 Vrms-supplied systems.