## 1 Introduction
It should be noted that often, such failures could be very difficult to detect. In case, for example, of a short-circuit failure, in some conditions, the current in the winding associated with the faulty device does not increase to accentuated values [30]. The main developed fault detection methods have been based on sensing two variable types: voltage and current. Methods that are based on voltage sensors are presented in [31; 32]. The first proposal is based on the analysis of the voltage patterns. For this analysis, it was used a method based on symmetry indexes. In these approaches, it is required the use of a voltage sensor for each of the windings. Other approaches based on voltage sensors have also been proposed. This is the case of the method presented in [33] which requires an extra \(DC\)-\(link\) current sensor. Regarding the methods based on current sensors, these have been considered more interesting. With the purpose to use the inherent current sensors associated with the motor windings, a method based on the average values of those currents was proposed in [34]. In [35] it was proposed a method to diagnose the \(SRM\) drive through the use of Wavelet Packet Decomposition. Another approach based on the current sensor is proposed in [36]. This allows for a real time diagnosis and is able to determine the location of the faulty power device. However, it requires a different power topology to include one or two current sensors, which are not linked to the current sensors associated with the motor windings. As referred, \(SRM\) machines and drives with fault-tolerant capability could be very important in several applications. One of the applications in which that capability is critical is on aircrafts since the security of the passengers and crew is at stake. So, a research about the use of an \(SRM\) with fault-tolerant capability for an electromechanical actuator that moves a rudder or an aileron of an aircraft was presented in [32]. In [33] it is presented an \(SRM\) configuration that is applicable for a fuel pump drive in an aircraft. In the work [34] permanent magnet assist, segmented rotor, switched reluctance drive has been constructed, tested and shown to be a strong contender for aerospace applications. Another application in which high reliability is critical is the nuclear power plant. In this context, in [35] was presented a fault-tolerant control strategy for the failure of the power converter of \(SRM\) valve electric actuator used in nuclear power plants. The use of \(SRM\) machines with fault tolerance capability can also be very important in electric vehicles [36]. With the purpose to obtain a reliable \(SRM\) drive a new fault-tolerant power converter scheme associated with a fault detection and diagnosis algorithm for power devices is proposed in this paper. For the detection of a failure in the power semiconductors of the \(SRM\) drive, it is proposed a fast and reliable fault diagnosis algorithm. This algorithm can detect open or short-circuit failures in power semiconductors of the power converter. It also generates normalized indexes in order to be immune to load and speed conditions. Besides the fast response, the proposed algorithm also presents robustness to problems related to noise. Several simulation and experimental results will be presented to demonstrate the proposed fault-tolerant solution.