Multi-Physical Signature Analysis of Induction Machines under Unbalanced Supply Voltage

This paper investigates the effect of voltage unbalance fault on current, vibration, acoustic noise and instantaneous power of an open-loop-controlled 1/3 HP and a closed loop controlled 3 kW induction machine drive. Experimental tests are performed in the form of run-ups and the results are plotted as colormaps to visualize the effect of the unbalance in a large speed range. Based on the observation of these plots, the relevant orders are tracked to compare their evolution with speed, load and unbalance severity, emulated by an increasing resistance inserted on one phase up to the open-phase fault case. It turns out that the analysis of the computed instantaneous power and the estimated RMS current is more suited for a reliable diagnosis in all cases.