This paper deals with an on-line fault detection method for multi-phase PMSM drives. The method is based on the detection of the stator current positive- and negative sequence fundamental components expressed in the stationary αβ reference frame. These components allow calculating a fault index used for the detection of stator faults, such as open-circuit faults. The decision criterion is based on the CUSUM algorithm. A model of a five-phase machine with one single-phase open-circuit is derived and validated with experimental results. Then, it is shown that the proposed method achieves fault detection on a wide speed range and even during speed transient.