An Overview of Fault-Diagnosis and Fault-Tolerance Techniques for Switched Reluctance Machine Systems <s> C. TRIAL AND ERROR METHOD <s> Accurate fault identification allows the adoption of procedures that minimize the fault impact on the machines operation. Switched reluctance motors (SRMs) have been recognized for their fault-tolerant capabilities and they present a very robust configuration, particularly due to the absence of windings or magnets in the rotor. All these attributes make the SRM a competitive solution for aircraft and automotive applications, where systems reliability is a crucial feature. Therefore, in this paper, a new algorithm for real-time diagnosis of power converter faults in SRM drives is proposed. In contrast to other methods that use additional sensors or devices, the presented technique uses the measured phase currents only, which are already available for the drive control. The proposed algorithm effectively detects the inverter faulty phase and is capable to localize the faulty power switch. Power switch open-and short-circuit fault occurrences in an asymmetric full-bridge converter are considered and analyzed. <s> BIB001 </s> An Overview of Fault-Diagnosis and Fault-Tolerance Techniques for Switched Reluctance Machine Systems <s> C. TRIAL AND ERROR METHOD <s> This paper presents a comprehensive method for eccentricity fault diagnosis in switched reluctance machine (SRM) during offline and standstill modes. In this method, the fault signature is achieved by processing the differential currents resulted from injected high-frequency diagnostic pulses to the motor windings. For feasibility assessment of the proposed method, the correlation between differential current and eccentricity occurrence is analytically demonstrated. A 3-D transient finite-element method is utilized to analyze the proposal, and its results are validated by experimental tests on a prototype machine in the laboratory. According to the obtained results by experimental as well as numerical analysis, a pattern is introduced in order to detect fault presence. In this stage, an algorithm with two methods is proposed for the detection of fault location or faulty phase. Furthermore, the direction of fault is recognized by a simple comparative technique. Next, a normalized indicator is proposed in order to estimate the eccentricity fault severity as well as its occurrence. This indicator is not dependent of the healthy motor information, which makes it reliable and applicable tool for all sizes of SRMs. Finally, a simple procedure based on achieved pattern and indicator is implemented to distinguish the static, dynamic, and mixed eccentricity in the SRM. <s> BIB002
In order to achieve a real-time fault diagnosis, the trial and error (TE) method can be employed due to simple and practical features. In BIB001 , a comprehensive fault location technique is proposed to identify the fault component after detecting the fault. If the open-circuit fault is detected, the controller compels the upper switch to turn on and the lower switch to turn off. The demagnetization time is obtained for distinguishing which switch has open-circuit fault. Similarly, once the shortcircuit fault is found, both switches in the affected phase are turned off to decrease the current. subsequently, the upper switch is turned on to test which switch is short-circuited. If the upper one is short-circuited, the phase current will increase rapidly. Otherwise, the current keeps zero, which means the short-circuit fault occurs in the lower switch. The TE method based fault diagnosis procedure for the determination of open-and short-circuit faults is exhibited in Fig. 13 . TE method can also be used for eccentricity fault detection BIB002 . For the three-phase SRM, two high frequency (HF) test signals are injected into two separated coils of phase A respectively when phase A is at the aligned position. Then the HF signals are injected into phase B and phase C in the same way. All the coil currents are measured. The amplitudes of differential currents of separated coils in one phase are recorded for comparison. The differential currents are sensitive to air gap variation, which is quite effective to detect the degree of rotor eccentricity fault.