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The rare-earth (RE) permanent magnets (PM) have been increasingly adopted in traction motor application. However, the RE PM is expensive, less abundant, and has cost uncertainties due to limited market suppliers. This paper presents a new design of a RE-free five-phase ferrite permanent magnet-assisted synchronous reluctance motor (Fe-PMaSynRM) with the external rotor architecture with a high saliency ratio. In such architecture, the low magnetic coercivity and demagnetization risk of the ferrite PM is the challenge. This limits the number of flux barriers, saliency ratio, and reluctance torque. A precise analytical design procedure of rotor and stator configuration is presented with differential evolution numerical optimizations by utilizing a lumped parameter model. A 3.7 kW prototype is fabricated to validate the proposed idea. [ABSTRACT FROM AUTHOR]

This study presents a novel frequency determination algorithm for the magnet temperature estimation of a five‐phase permanent magnet assisted synchronous reluctance motor (PMa‐SynRM) using the signal injection method. The signal injection method is a convenient and non‐invasive approach to determine the magnet temperature in permanent magnet motors by exploiting the temperature dependency of magnet resistance. However, its implementation as a magnet temperature estimation tool warrants an adaptive frequency determination method in order to ensure its effective employability under more pragmatic dynamic operations. The proposed method in this study proposes an analysis of the frequency spectrum to isolate the fundamental and fault frequencies and their respective harmonics to determine a range of available frequencies that may be employed in this method. The available frequencies are further concentrated based on the signal‐to‐noise ratio constraints. As an additional part of the contribution of this study, an innovative rotating hardware set‐up is developed which would transmit the magnet temperature data wirelessly to verify the accuracy of the proposed temperature estimation algorithm. [ABSTRACT FROM AUTHOR]

This study presents the design of a robust five-phase ferrite (Fe) permanent-magnet-assisted synchronous reluctance motor (PMaSynRM) to mitigate two major design challenges: irreversible demagnetization and mechanical deformation. Recently, rare-earth magnet-based five-phase PMaSynRMs have been proposed for vehicular applications due to their better fault tolerance, higher torque density, and low torque ripple compared to their three-phase counterparts. However, rare-earth magnets are expensive and, their supplies were disrupted multiple times in past few years. Therefore, to avoid rare-earth magnets in traction motors, this study proposes a five-phase PMaSynRM with Fe magnet. Special attention is paid to avoid irreversible demagnetization and deformation as these are two major concerns in any Fe-based machine. The rotor structure is uniquely optimized with additional geometrical parameters to reduce the risk of irreversible demagnetization. To increase the structural stability of the rotor, optimal center post and weight reduction notches are adopted. The proposed Fe-based five-phase PMaSynRM has been comparatively studied over a rare-earth magnet-based PMaSynRM. The lumped parameter model and finite element model have been utilized for design optimization and performance analysis. Finally, A 3 kW prototype of the proposed five-phase Fe PMaSynRM has been fabricated, experimentally tested, and compared with the benchmark rare-earth PMaSynRM to validate the proposed design and simulations results. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach for open-phase fault detection of a five-phase permanent magnet assisted synchronous reluctance motor (PMa-SynRM). Under faults, the five-phase PMa-SynRM is expected to run at fault-tolerant control (FTC) mode, otherwise it draws a large amount of current with a significant reduction in the reluctance torque. To successfully achieve FTC operation of five-phase PMa-SynRM, the accurate detection of a fault condition has to be preceded. With the best of these authors knowledge, the detection of faults has been limitedly studied for five-phase motors. The analysis of open-phase fault in five-phase machine involves complicated conditions including single-phase open fault, two-phase adjacent fault, and two-phase nonadjacent fault. To perform the timely fault-tolerant operation, those faults have to be accurately analyzed and detected. In this paper, a novel symmetrical components (SCs) analysis is utilized to extract the feature of those fault conditions. This analysis will provide the types of faults by logically analyzing the pattern of magnitude and phase angle changes of the fundamental signal in the SCs. The proposed method has been comprehensively analyzed through theoretical derivation, finite-element simulations, and experimental testing through a 5 hp PMa-SynRM controlled by TI-DSP F28335. [ABSTRACT FROM PUBLISHER]