Detecting faults in inverter-fed induction motors during startup transient conditions

This paper presents a fault detection methodology for inverter-fed induction motors during startup transients. The most popular detection technique for steady state analysis is based on the Fast Fourier Transform (FFT). The inverter switching operation affects the harmonic content of the current. Thus, it becomes more difficult and demanding to detect faults in inverter-fed motors using the classical approach, furthermore it cannot be applied when the inverter-fed motor is not in steady state. This detection methodology is based on detecting the transient evolution of the fault related harmonics and may be used to complement the classical approach. This detection methodology has been successfully applied to a low voltage inverter-fed healthy motor and a motor with an inter-turn fault.