In this paper we present a technique for detecting broken bars of an induction motor (IM), by injecting zero sequence high frequency signals. Through the processing of currents induced in response to the injected signal, the variation is analysed, and how the occurrence of failures on such bars modify diagnostic signals, allowing the detection of the fault. The main characteristic of the presented method is that the high frequency zero-sequence signals are generated by the standard vector modulation of the inverter. Laboratory results demonstrate the validity of the technique for detecting faults in bars in IM.