Robust induction machine cage monitoring technique for highly distorted voltage and current waveforms, the Vienna method

This paper addresses the sensitivity and robustness of the online model based Vienna monitoring method. Experimental results from a PWM inverter drive demonstrate the robustness with respect to highly distorted voltage and current waveforms. Under this conditions a cracked bar has been clearly detected. Fault related torque pulsation leads to speed oscillations. This effect is examined with the help of results from both a speed and a torque controlled mode experiment. The field test results do not indicate any noticeable deterioration. Finally, transient load torque is utilized to produce the required rotor currents for fault detection. Although several acceleration cycles are required to excite currents in any rotor bar and data can only be recorded during maximum acceleration the results are remarkably close to the steady state values.