Markov Reliability Modeling for Induction Motor Drives Under Field-Oriented Control

This paper presents a Markov reliability model of induction motor drives operating under field-oriented control. The model includes faults in the power electronics, machine, speed encoder, and current sensors. The procedure can be extended for more detail, to other machines and to other drive topologies. To develop the model, faults are first identified, and then, a simulation model of the setup is developed and experimentally verified. Faults are injected into the model in sequential levels and the system performance is assessed after each fault. Fault coverage-the probability that the system survives given a fault has occurred-is studied. A complete Markov reliability model is developed to assess the mean time to failure of the system and other reliability factors. This analysis is shown to be simple and useful for assessing the reliability of motor drives and is expected to help in designing fault-tolerance mechanisms for specific drives, where reliability can be evaluated after every design.