Speed sensor fault tolerant direct torque control of induction motor drive

The paper deals with the fault tolerant Direct Torque Control of an induction motor drive. Influence of the speed sensor faults to the properties of the DTC-SVM drive system is presented. Control structure with and without outer speed control loop is analyzed. Simple algorithmic mechanism of the speed sensor fault detection is described. During the faulted conditions vector controlled drive is switched to the sensorless control structure with MRAS^CC speed and flux estimator. Dynamical performance of the fault-tolerant vector control system (FTDTC-SVM) with the current-type MRAS estimator are tested in simulation and in the laboratory set-up with 50kW machine. Control structure is checked under faulted and post-fault conditions, in low speed and in field weakening regions.