This study presents a generalised fault diagnosis method for power transistors in the asymmetric half-bridge power converter of switched reluctance motor (SRM) drive. In order to extract the remarkable fault features, three current sensors are rearranged. Each phase current can be calculated by solving the equations associated with the detected values of three current sensors and three coefficients obtained based on different switching states. Different faults are preliminarily detected by monitoring the error between the estimated bus current and the actual bus current. After the identification of fault occurrence, the error will be calculated with all the combinations of three coefficients. The minimum error will be found and the corresponding coefficients are recorded. The fault types and fault power transistors are located by comparing the actual coefficients with the recorded coefficients. Being different from the existing methods, the developed diagnostic strategy can detect multiple fault types and can be used in different control modes, including voltage pulse width modulation, current chopping control and angular position control schemes. Moreover, the proposed technique is easy for online implementation without extra sensors and additional electric devices. The effectiveness of the proposed solution is validated on a three-phase 12/8 SRM drive.

This study presents a low-cost switched reluctance machine (SRM) drive system with reduced current sensors and position sensors. The reduction of current sensors is achieved by rearranging the location of adopted sensors, and each phase current is calculated by decomposing the current from two special positions. The reduction of position sensors is realised by optimising conventional slotted disc. Being different from the conventional three-phase 12/8 SRM drive system, the developed low-cost system only requires two current sensors and one position sensor. First, the proposed phase current detection method is illustrated in details. Second, the measures to solve the three key problems in rotor position sensing strategy are represented considering the forward and reverse direction of SRM. Third, the reliability function and the mean time to failure indicators are compared between the conventional and proposed methods. Finally, the effectiveness of the proposed methods is experimentally validated on a three-phase 12/8 SRM drive. The proposed low-cost system is easily extended to the widely used four-phase 8/6 SRM system. Moreover, the proposed strategies for the low-cost SRM drive system are not relying on the analytical motor model and easy for online implementation without additional hardware.

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