This paper presents a new fault diagnostic technique applied to switched reluctance motor drives, based on the analysis of the power converter supply current. A fault is detected when the measured amplitude of the dc bus current differs from its expected amplitude, assuming normal operating conditions. The information about phase currents amplitudes and the control commands of all power switches permit to easily estimate the amplitude of the power converter supply current, since an asymmetric bridge converter is used. Simulation and experimental results are presented. Open-and short-circuit fault occurrences in the converter power switches are considered and analyzed. The proposed technique can early detect these fault occurrences and can also identify the affected motor phase. In almost all situations, the faulty element is also identified. An early fault diagnosis, with an accurate fault identification, is of a paramount importance since it permits the early adoption of fault-tolerant procedures that minimize the fault impact on the machine operation.Index Terms-Fault analysis, fault diagnosis, switched reluctance motor (SRM), variable speed drives.

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One of the main features of a switched reluctance motor is its fault tolerance capability. However performance deterioration is clearly evident when one phase is removed. This paper presents a fault tolerant power converter, applied to a four phases switched reluctance motor. Some possible additional connections on the commonly used asymmetric bridge converter are introduced to secure the operation of all phases even after a fault occurrence responsible for a power converter switch disconnection. Simulated results indicate that normal operation can nearly be restored at low speed operation and SRM performance behavior is clearly improved at high speed operation. Dynamic operating conditions, under normal and faulty operations with and without the use of the fault tolerant power converter, are analyzed. A high speed operating example, for all the referred operating modes and considering the same speed and load conditions, is presented. Time-domain waveforms of the phase currents, power converter supply current, electromagnetic torque and mechanical speed are presented as well as the spectral analysis of the power converter supply current and electromagnetic torque.

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