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This study presents a new configuration for dual-channel switched reluctance motor (DCSRM) called as decoupled DCSRM (DDCSRM), which can be proposed as a suitable candidate for high-reliability applications. In this new DDCSRM, the two channels could be considered as two synchronously independent 6/4 three-phase SRMs with no mutual coupling when they are excited simultaneously. The machine topology and magnetic characteristics of flux distribution, static flux linkage and torque by using finite-element analysis are presented. Then, the mathematic models of the DDCSRM drive under normal and open-circuit fault operations are proposed. To achieve fault-tolerant operation, a control strategy of open-circuit faults for the DDCSRM drive is presented. The key of the fault-tolerant control strategy is to maintain the rotor speed as the normal motoring operation. The dynamic performances of the DDCSRM drive under normal and open-circuit fault conditions are analysed by using the control strategy. Finally, an experimental setup for a 12/8 DDCSRM drive system is built for verification. The experimental results at normal and various open-circuit fault conditions are presented to verify the control strategy of the DDCSRM drive system and the analytical and simulation results.

This study presents a novel switched reluctance machine (SRM) with modular E-core stators and multi-layer common rotors for high reliability applications. The stator is composed of six independent modular E-cores with the windings wound around the yoke of the E-cores. The rotor consists of three magnetically independent common rotors which are place in the same shaft without any angular shift. The equivalent magnetic circuit (EMC) models of this new SRM at the aligned and unaligned positions are described. To evaluate the motor performance, two types of analysis, namely, approximate simplified two-dimensional (2D) model and 3D model finite-element analysis (FEA) have been utilised. The 2D FEA static and dynamic results are compared with 3D FEA results. Furthermore, comparisons between the novel modular SRM and a conventional 6/4 SRM are made. Finally, a prototype of this modular SRM has been fabricated and tested in the laboratory. Comparison between FEA and EMC analysis for flux linkage are made and compared with measured characteristics. The simulated and measured phase currents and average torque are also presented and compared to verify the analytical and simulation results.

We investigated the hole injection mechanism in InGaN/GaN blue light-emitting diodes by growing monolithic dual-wavelength multiple-quantum-wells and measuring the electroluminescence spectra at different current densities under room temperature. By analyzing the spectral competition from quantum wells at different vertical locations, the hole injection depth was quantitatively measured. During the epitaxial growth, large size V-shape pits with 200–330 nm diameter were intentionally formed in the active region by controlling the growth condition. It was found that such defect has a significant influence on the hole injection depth. With large V-shape pits and reduced quantum barrier thickness, the hole can be injected beyond 8 pairs of quantum well/quantum barrier. And less “droop” effect at large current density were observed. A carrier transport model with the presence of large V-shape pits is established.

The variation of deflection and maximum stress of a nickel film microbridge with load was investigated over a wide range of length, thickness, elastic modulus and residual stress by both large and small deflection theories of microbridge testings. The limits of deflection and load for a microbridge to be deformed elastically were determined by the assumption that the maximum stress could not be more than the yield strength. Furthermore, the deflection and load limits of small deflection theory were decided by setting a threshold beforehand for the normalized deflection and maximum stress difference between large and small deflection theories. Based on the results above, the dimensions of the nickel microbridge samples were chosen and the deflection range suitable for the small deflection theory was calculated. The nickel film microbridge samples electroplated on a Si(100) substrate were fabricated by MEMS and the microbridge testings were conducted with a load and displacement sensing nanoindenter system. From small deflection theory, the Young's modulus and residual stress for the electroplated nickel films were calculated and the results were 190.5 GPa and 86.6 MPa, respectively.

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