Fault Tolerant Field Oriented Control of Induction Motor for Loss of One Inverter Phase with Re-starting Capability

This paper describes a novel strategy for restarting the three phase induction motor in a voltage fed field oriented drive operating in the single phase mode after the loss of one of the inverter phases. The proposed method makes use of the readily presented switches for isolating the machine phase corresponding to the faulty inverter leg in the fault tolerant induction motor drive. With the aid of the two healthy inverter phases, three phases of the machine and sequential switching of two switches, block currents are fed into the machine to produce net average positive torque capable of restarting the machine. After the machine reaches a suitable speed the control structure is changed to the single phase field orientated mode of operation. The strategy is verified by computer simulation on a 10 kW induction machine.