An Overview of Fault-Diagnosis and Fault-Tolerance Techniques for Switched Reluctance Machine Systems <s> 4) OPTIMIZED MOTOR DESIGN <s> In safety-critical systems, faults can cause life losses, environmental degradation, or significant financial losses. In this paper, a segmental stator switched reluctance machine is proposed for such applications. A short overview of its design is given. Its fault tolerance is investigated by dynamic simulations and laboratory tests. It is demonstrated via both methods that the proposed machine is able to have a continuous operation despite five severe winding fault conditions. <s> BIB001 </s> An Overview of Fault-Diagnosis and Fault-Tolerance Techniques for Switched Reluctance Machine Systems <s> 4) OPTIMIZED MOTOR DESIGN <s> A modular stator switched reluctance motor (SRM) for fault tolerant drive systems is proposed. Owing to the particular construction of the stator there is no mutual coupling between adjacent phases. Hence, the motor can work also when a part of the coils is faulted and the faulted modules can be replaced without uncoupling the machine from the load or gearbox. The sizing particularities are presented and the mathematical model of the motor is developed. The results obtained via finite element analysis are compared with the analytical ones, and with that resulting after testing the constructed laboratory model. All these prove that the proposed SRM can be used in safety–critical drives. <s> BIB002 </s> An Overview of Fault-Diagnosis and Fault-Tolerance Techniques for Switched Reluctance Machine Systems <s> 4) OPTIMIZED MOTOR DESIGN <s> This paper presents the design, analysis, prototype, and testing of a new fault tolerant electrical drive topology. The segmented rotor switched reluctance machine (S-SRM) has been modified to include permanent magnet assist by placing magnets in the stator slot opening. This introduces a magnetic bias which extends the magnetic operating region of the machine and results in greater torque when compared to the conventional fault tolerant segmental rotor switched reluctance machine. This new torque dense, fault tolerant topology was investigated using 2-D (two-dimensional) and 3-DFE methods and a prototype machine built, tested and verified against the simulations. Experimental testing was carried out with and without the magnets to assess the effect of the PM assist on torque performance. Static tests were carried out to obtain the torque—flux linkage—angle waveforms and then this information used to tune a bespoke drive and test the system under dynamic conditions. The superior fault tolerant performance of this PMA S-SRM topology is highlighted by measurements taken under phase open and short circuit fault conditions. The tests show that this fault-tolerant topology not only meets the mass requirements of the aerospace application, set originally by a PMSM, but also, with the magnets now placed on the stator the rotational induced EMFs and associated short circuit currents during a fault are drastically reduced. Hence the fault tolerance of this topology is an improvement on the PMSM topology, and it will be of benefit to fault critical systems such as aerospace drives and actuators. <s> BIB003
The primary purpose of fault tolerance is to mitigate the shortcircuit currents in short-circuit fault and improve the motor torque performance in open-circuit fault. This target can be achieved not only by controlling power switches or figure out new converter topology, but also by optimized motor structure in the motor design process BIB003 - BIB001 . In BIB003 , permanent magnetics (PMs) are inserted into the tooth of the stator which improves the torque characteristic and reduces the induced EMFs. As a result, the EMFs are drastically reduced under open-circuit faults. For short-circuit faults, optimized PM placement strategy minimizes the EMFs and suppresses the peak current value. The fault-tolerance capability is enhanced by the PM assistance, which dramatically improves the reliability of the SRM drive system, and segmental rotor also improves the torque density. In BIB002 and BIB001 , a particular design of stator with spacers is illustrated in Fig. 20 for four-phase SRM to improve the phase independence and enhance open-circuit fault-tolerant capacity. The coils are wounded tangentially on segments of the stator and controlled independently by power converter. The modular stator structure offers a mutually independent short magnetic path, enabling simple manufacturing of stator and convenient replacement of faulty stator blocks without disconnecting from the load. Compared to the conventional 8/6 four-phase SRM, lower torque ripple and less iron loss are validated by simulation and experiment. Although the average torque decreases as the number of opened coils increases, the efficiency stays the same.