Design of a neutral point clamped power inverter

This thesis details the design, construction, and preliminary testing of a Neutral Point Clamped Power Inverter. The inverter is designed for the 100 kilowatt class of inverters and has a three phase output connection and a neutral connection.

The inverter is designed around insulated gate bipolar transistor as the power switching devices. The inverter employs software generation of the gate signals for the power switches and gate driver electronics to ensure reliability and insulation between the high power and low power circuitry.

The inverter produces a true three level line-to-neutral voltage waveform and a true five level line-to-line voltage waveform. The true descriptor indicates that a zero voltage output is not produced by averaging two potentials. Rather, a zero voltage output is produced by connecting the output voltage to a neutral point. To date, the inverter has been tested at 20 kilowatts of continuous power.