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Abstract
An in-depth analysis of a distinctive machine topology characterized by a doubly salient structure and integrated permanent magnets within the stator is presented in this dissertation. The machine exhibits exceptional power density performance of upto 50kW/L, capable of operating at a rated torque of 95Nm at a rated speed of 12,500rpm, and maximum speed of 37,500rpm with a specific focus on its relevance to electric vehicle traction applications. The machine comprises 12 stator segments and coils configure for three-phases, interspersed with 12 PMs in the stator, along with a reluctance-type rotor featuring 10 protrusions equivalent to 20 electric poles.An analytical model for this novel machine configuration is developed using lumped parameter magnetic equivalent circuits (LPMEC), encompassing stator segments, permanent magnets (PM), toroidal windings, air gap, and a reluctance-type rotor. In contrast to prior analytical methods, the proposed methodology thoroughly investigates spatial harmonics, elucidating the non-saliency behavior of the machine. The LPMEC model is employed to compute critical parameters such as flux linkages, open circuit back EMF, and inductances with respect to the rotor position. These outcomes are validated through finite element analysis. Intriguingly, despite its inherently doubly salient structure, the proposed machine exhibits characteristics similar to a non-salient machine such as surface permanent magnet machine. This behavior is substantiated by the scrutiny of spatial harmonics. For comprehensive evaluation, a high-fidelity model-based motor drive system is developed. A field-oriented control approach is adopted to regulate torque and speed across a broad spectrum encompassing constant torque and field weakening regimes. Further, a complex vector current (CVC) regulation strategy is introduced to account for the substantial variations in inductances with rotor position. Unlike classical current regulation strategies in synchronous reference frames, the CVC strategy is more robust despite uncertainties related to the estimation of d-q inductances of plant model, thus enhancing the stability of the control system. In-depth comparative analysis between the classical synchronous reference frame proportional integral current control and CVC regulation strategies is conducted. A detailed stability analysis reveals the robustness of the CVC regulation strategy without the need for decoupling feed-forward voltages compared to the classical proportional integral current regulation strategy with decoupling voltages. The efficacy of these regulation strategies is validated through extensive simulations in the continuous domain and substantiated through controller hardware in the loop (CHIL) experiments. Experimental tests have been conducted to validate the analytical outcomes and proposed control methodologies employing an open frame laboratory prototype (OFLP) of the proposed machine and SiC based traction inverter.