Unified SVPWM Strategy for Post-Fault Three-Level NPC Voltage Source Inverters

Eight switch three-phase inverters (ESTPIs)are the reconfigured topologies of the three-level neutral-point-clamped (NPC)inverter with a failure leg. This failure leads to different topologies of ESTPIs, which can be controlled by different space vector pulse width modulation (SVPWM)strategies. By analyzing the relationship of three SVPWM strategies for different ESTPIs, a unified coordinate transformation is proposed, which can make one of the three SVPWM strategies be a unified control strategy of ESTPIs. And the unified coordinate transformation is suited for two different SVPWM strategies for ESTPIs. Consequently, the unified strategy not only simplifies the control strategy, but also makes the fault tolerant control strategy more flexible. Simulation and hardware-in-the-loop (HIL)test results have shown the validity and feasibility of the proposed unified SVPWM strategies.