Abstract
This paper proposes an algorithm for fault tolerance of three-phase, inverter-fed, speed-sensor-less control of a three-phase induction motor drive system. The fault tolerance of the inverter when one switch is open or one leg of six-switch inverter is lost is considered. The control of the drive system is based on indirect rotor field-oriented control theory. Also, the speed estimator is based on model reference adaptive system (using stator current and rotor flux as state variables for estimating the speed). The fault-tolerant algorithm is able to adaptively change over from a six-switch inverter to a four-switch inverter topology when a fault occurs; also, it makes a smooth transition of the motor speed, torque, and current when changing over from a faulty condition to a new healthy status, which is four-switch three-phase inverter (FSTPI) topology; thus, the six-switch three-phase inverter (SSTPI) topology (pre-fault status) is almost retained for the medium-power range of induction motor applications. The proposed algorithm is simulated by using the MATLAB/SIMULINK package. Also, the proposed control system is tested experimentally using a digital signal processor (DSP1104). The obtained results from the simulation model and experimental system demonstrate the performance enhancement and good validity of the fault-tolerance control for the speed-sensor-less induction motor drive system. (C) 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.