Abstract: HHT is a new method of signal processing, which has time-frequency adaptively. It can be used to analyze all kinds of signals, including stationary, non-stationary, linear, non-linear etc. The core of HHT EMD is flattering, which shows the signal in sum of different scale sequences, and instantaneous time-frequency spectrum can reflect physical significance precisely. HHT is used to process rotor broken signal of cage motor, and it shows effective and accurate. The method does not need large numbers of data, and the cost of hardware and software can be saved.

Key words: HHT, instantaneous time-frequency spectrum, rotor broken, stator current, signal analysis