Electric machine utilization during the post-fault operation after inverter open circuit faults

Inverter open circuit faults (IOCFs) in AC drives lead to undesired effects and thus, the reconfiguration of the drive to a post-fault operation mode is desirable. In the past some authors have proposed drive topologies and operation strategies to keep the drives operating after IOCFs. However, increased losses and temperatures during these post-fault operation modes lead to a reduced performance of the machine. This paper analyzes the occurring losses and the thermally defined operation limits of an induction machine during the post-fault operation. The analysis is performed by means of symmetrical components, finite element analysis and lumped parameter models.