Patent ID: 7088073

Claim:
A method of driving a motor load using an inverter drive system to continue operation during a failure mode, the inverter drive system comprising three single vale NPC inverters connected to each other via a plurality of contactor switches adapted to connect the single vole NPC inverters ma plurality of configurations, the method comprising: switching some of the contactor switches to connect the single pole NPC inverters in a star configuration; driving the motor load using the inverter drive system in the star confinuration during a nornal mode of operation; and switching some of the contactor switches to connect the single pole NPC inverters in a second continuation in which a first and a second non-damaged single pole NPC inverter of the three single pole NPC inverters are connected to drive the motor load when a third single pole NPC inverter of the three single pole NPC inverters has failed; wherein for the step of switching some of the contactor switches to connect the single pole NPC inverters in a second configuration, the second configuration comprises a mesh V connection.