Induction motor-drive systems with fault tolerant inverter-motor capabilities

A low-cost fault tolerant drive topology for low-speed applications such as "self-healing/limp-home" needs for vehicles and propulsion systems, with capabilities for mitigating transistor open-circuit switch and short-circuit switch faults is presented in this paper. The present fault tolerant topology requires only minimum hardware modifications to the conventional off-the-shelf six-switch three-phase drive, with only the addition of electronic components such as triacs/SCRS and fast-acting fuses. In addition, the present approach offers the potential of mitigating not only transistor switch faults but also drive related faults such as rectifier diode short-circuit fault or dc link capacitor fault. In this new approach, some of the drawbacks associated with the known fault mitigation techniques such as the need for accessibility to a motor neutral, overrating the motor to withstand higher fundamental rms current magnitudes above its rated rms level, the need for larger size dc link capacitors, or higher de bus voltage, are overcome here using the present approach. Given in this paper is a complete set of simulation results that demonstrate the soundness and effectiveness of the present topology.