Induction motor drive behavior during unbalanced faults

The ability of an induction motor drive to ‘ride through’ short-term power system faults or voltage dips of several cycles is of interest in processing plants where shutdowns are expensive. In this paper, the rectifier/inverter induction motor drive is modeled to include the effects of an unbalanced supply circuit, such as that caused by a fault in the supply. A three-phase diode bridge rectifier is used to simulate the effects of the overlap angle caused by the unbalanced source reactance and associated harmonics. The filter circuit between the rectifier and inverter is included. A detailed switching function model is chosen for the inverter so that generated harmonics are included in the motor voltage. Experimental results are included.