INDUCTION-MOTOR DRIVE BEHAVIOR DURING UNBALANCED FAULTS

The ability of an induction motor drive to 'ride through' short-term p ower system faults or voltage dips of several cycles is of interest in processing plants where shutdowns are expensive. In this paper, the r ectifier/inverter induction motor drive is modeled to include the effe cts 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 react ance and associated harmonics. The filter circuit between the rectifie r and inverter is included. A detailed switching function model is cho sen for the inverter so that generated harmonics are included in the m otor voltage. Experimental results are included.