Abstract
This paper presents an effective fault diagnostic and tolerant method for an open-gate fault of a three-phase inverter. The induction motor (IM) drive system is controlled by a speed sensorless indirect rotor field-oriented control (IRFOC). The proposed diagnostic method requires low computation to detect open-gate faults. This method uses a simple direct current technique based on the measured motor currents to detect faulty switch. The fault-tolerant scheme is based on changing the inverter topology from six to four switches to ensure proper operation. In the faulty case, the fault-tolerant technique disconnects the motor phase terminal from the faulty arm of the inverter and connects it to the midpoint of the DC-link via an external switch. The performance of the IM drive is investigated and analysed under normal, faulty and post-fault operations through simulation and experiment. The results demonstrate the effectiveness of the fault diagnostic and tolerant method for retaining almost the normal performance of the IM drive system.