As one of the oldest machine topologies, the concept of synchronous reluctance (REL) machine can be traced back as early as 1900s. In the last 20 years, particularly, the REL machines have attracted more and more attention in both academic and industrial fields. Without permanent magnets and rotor bars, the rotor construction of the REL machine is more robust than either permanent magnet (PM) machines or induction machines (IMs). In addition, it achieves the merits of low cost, low maintenance, and high reliability. All these features reveal the REL machine to be an attractive alternative to the widely used machine topologies. Therefore, the investigation of REL machines is essential, and specific applications will be of great interest. In this thesis, the design and analysis of high performance REL machines are developed and discussed. Furthermore, two particular applications are investigated: REL motors for electric vehicle (EV) applications and self-excited reluctance generators (SERG) for isolated wind applications.
To start with, the transversely-laminated anisotropy rotor type with multiple flux-barriers is chosen to be designed and analyzed. More specifically, a detailed parametric analysis of this kind of rotor geometry is carried out, which aims to suggest an automatic drawing and simulating procedure. The shape of flux-barriers is selected to achieve both high d-axis inductance and low q-axis inductance. Methods to properly design the geometry of barrier ends and PMs are adopted. Some tuning steps are suggested in order to achieve the high performance design. Such a procedure is then used to rapidly analyze the impact of some rotor parameters on the machine performance, in order to provide a guideline for the preliminary design of the REL machine. After that, as a practical example, a REL motor according to the dimension of a commercial motor is designed. Certain design procedures are followed, and optimization is also carried out. The performance comparisons between the optimized REL motor and the commercial product are given. Merits and defects of the REL machine for EV application are highlighted.
The study on SERG starts with the recognition of the steady-state performance, both analytically and experimentally. The conditions related to successful self-excitation in SERG, such as required capacitance, rotor residual magnetism, rotor acceleration and pre-charging capacitors, are investigated. The possibility to adopt self-excited PM-assisted reluctance generator is also dealt with, and the performance comparison with SERG is made. The effect of some design parameters on the performance of the PMAREL generator is analyzed. Referring to wind applications, the method to maintain the generated voltage constant at variable speeds is proposed. Finally, the prediction of the "optimal capacitor and resistor combination" that achieves the maximum utilization of the mechanical power produced by the wind turbine will be presented
