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This paper presentsan investigation of a 3D-magnetic flux permanent magnet synchronous motor (3D-MF PMSM) used for electric vehicle applications. The investigated 3D-MF PMSM consists of an integrated radial-flux and axial-flux structure. It has two radial-flux air-gaps and two axial-flux air-gaps, as well as a toroidal winding wound stator. The integrated structure helps to concentrate all the flux within the motor to maximize torque production. Moreover, there are no end-windings in this motor and all the stator windings effectively are used in torque production. A comprehensive performance evaluation, in terms of the back-electromotive force, average output torque, cogging torque, torque ripple, flux-weakening capability, etc., of the investigated 3D-MF PMSM is conducted. An interior PMSM is purposely included as a benchmark for comparison. The results show that compared to the benchmark interior PMSM, the original 3D-MF PMSM exhibits significantly improved torque density, higher power factor, and higher efficiency, but suffers from serious cogging torque and torque ripple. Accordingly, a skewed arrangement is introduced to the 3D-MF PMSM. As a result, the cogging torque and torque ripple are significantly reduced. [ABSTRACT FROM AUTHOR]

Flux-switching permanent magnet (FSPM) machines have been gaining interest over the last few decades. This is due to the several advantages that this type of machines provides. These advantages include high torque density due to the flux-focusing effects, favorable thermal management due to the location of PMs on the stator, passive and hence robust rotor structure which is suitable for high-speed applications, etc. The two-part companion articles are going to provide a comprehensive analysis of FSPM machines in terms of opportunities and challenges. In the first part of these two-part series, it covers the principle theory, computation methods, various topologies of FSPM machines, and the comparison with other PM machines. Meanwhile, the basic performance characteristics and design requirements, viz. torque density, over-load torque capability, flux-weakening capability, fault-tolerance capability, as well as the latest development, are also provided. [ABSTRACT FROM AUTHOR]

Flux-switching permanent magnet (FSPM) machines have received an intense amount of research interest in recent years, due to their advantages of high torque/power density, favorable thermal management, as well as passive and robust rotor structure. The purpose of this two-part companion articles is to provide a comprehensive overview of FSPM machines in terms of opportunities and challenges. In the early part of this two-part series, the operating principle, the modeling methods, the various machine topologies of FSPM machines, as well as the comparison with other PM machines, have been analyzed and investigated. Building upon Part (I), this article covers the analysis and design of winding configurations, the practical techniques to minimize the cogging torque and torque ripple, the control strategies, the technical challenges, as well as the emerging trends of FSPM machines. Moreover, the key features of the FSPM machines, including the merits and demerits of such machines as well as their associated techniques, are highlighted and summarized. [ABSTRACT FROM AUTHOR]

A comparative study of five-phase outer-rotor flux-switching permanent magnet (FSPM) machines with different topologies for in-wheel traction applications is presented in this paper. Those topologies include double-layer winding, single-layer winding, C-core, and E-core configurations. The electromagnetic performance in the low-speed region, the flux-weakening capability in the high-speed region, and the fault-tolerance capability are all investigated in detail. The results indicate that the E-core FSPM machine has performance advantages. Furthermore, two kinds of E-core FSPM machines with different stator and rotor pole combinations are optimized, respectively. In order to reduce the computational burden during the large-scale optimization process, a mathematical technique is developed based on the concept of computationally efficient finite-element analysis. While a differential evolution algorithm serves as a global search engine to target optimized designs. Subsequently, multiobjective tradeoffs are presented based on a Pareto-set for 20 000 candidate designs. Finally, an optimal design is prototyped, and some experimental results are given to confirm the validity of the simulation results in this paper. [ABSTRACT FROM AUTHOR]

This paper introduces a general method for determination of the most suitable winding configurations for five-phase flux-switching permanent magnet (FSPM) machines, associated with feasible stator/rotor-pole combinations. Consequently, the effect of winding configurations on the performance of a five-phase outer-rotor FSPM machine is thoroughly investigated, including non-overlapping concentrated windings (single-layer, double-layer, and multi-layer) as well as distributed winding. The electromagnetic characteristics in the low-speed region, the flux-weakening capability in the high-speed region, and the fault-tolerant capability under faulty situations are evaluated and compared in detail. This work shows that compared with the conventional single-layer or double-layer concentrated windings, the FSPM machine with multi-layer type winding exhibits lower torque ripple and losses. Meanwhile, the motor with distributed windings possesses higher torque density and larger inductance. Finally, a prototype is manufactured, and the analysis results are validated by experiments. [ABSTRACT FROM AUTHOR]

A five-phase dual-rotor permanent-magnet synchronous motor (PMSM) used for electric vehicles is investigated in this paper. The dual-rotor PMSM consists of an inner motor and an outer motor, which share a common stator yoke. The magnetic coupling exists not only within the interphases, but also between the inner and outer motors, which leads to control complexity and affects performance and fault-tolerant capability of the motor. Thus, the electromagnetic characteristics, particularly the magnetic-coupling characteristics of the dual-rotor PMSM, are investigated based on magnetic circuit and finite-element methods. The influences of magnetic coupling caused by the structural arrangement (pole/slot combination, magnetization type of PMs, armature reaction, common stator yoke thickness, and winding structure) are analyzed in this paper. Then, a magnetic decoupling design is introduced for the five-phase dual-rotor PMSM. A prototype was manufactured and tested to verify the validity and accuracy of the process presented in this paper. [ABSTRACT FROM AUTHOR]

A fault-tolerant technique for motor-drive systems is introduced in this paper. The technique is merely presented for ac motors with Δ-connected circuits in their stator windings. In this technique, the faulty phase is isolated by solid-state switches after the occurrence of a failure in one of the stator phases. Then, the fault-tolerant technique manages current-flow in the remaining healthy phases. This technique is to significantly mitigate torque pulsations, which are caused by an open-Δ configuration in the stator windings. The performance of the fault-tolerant technique was experimentally verified using a 5-hp 460-V induction motor-drive system and the results are presented in this paper. [ABSTRACT FROM AUTHOR]

Fault-tolerant operation of induction motors fed by soft starters when experiencing thyristor/silicon-controlled rectifier open-circuit or short-circuit switch fault is presented in this paper. The present low-cost fault mitigation solution can be easily retrofitted, without significant cost increase, into the existing off-the-shelf three-phase soft starters to enhance the reliability and fault-tolerant capability of such soft starter systems. In the event of either thyristor open-circuit or short-circuit switch fault in any one of the phases, the fault-tolerant soft starters are capable of operating in a two-phase control mode using a novel resilient closedloop control scheme. The performance resulted from the present fault-tolerant soft starter control has demonstrated reduced motor starting transient torque pulsations as well as reduced motor inrush current magnitude. The present fault-tolerant approach is applicable to any soft starters that control small to large integral horsepower induction motors. Simulation results along with supporting experimental results for a 1.492-kW, 460-V, four-pole, three-phase induction motor are presented here to demonstrate the soundness and effectiveness of the present fault-tolerant approach. [ABSTRACT FROM AUTHOR]

The benefits and drawbacks of a 5-hp reconfigurable induction motor, which was designed for experimental emulation of stator winding interturn and broken rotor bar faults, are presented in this paper. It was perceived that this motor had the potential of quick and easy reconfiguration to produce the desired stator and rotor faults in a variety of different fault combinations. Hence, this motor was anticipated to make a useful test bed for evaluation of the efficacy of existing and new motor fault diagnostics techniques and not the study of insulation failure mechanisms. Accordingly, it was anticipated that this reconfigurable motor would eliminate the need to permanently destroy machine components such as stator windings or rotor bars when acquiring data from a faulty machine for fault diagnostic purposes. Experimental results under healthy and various faulty conditions are presented in this paper, including issues associated with rotor bar-end ring contact resistances that showed the drawbacks of this motor in so far as emulation of rotor bar breakages. However, emulation of stator-turn fault scenarios was successfully accomplished. [ABSTRACT FROM AUTHOR]

A robust interturn fault diagnostic approach based on the concept of magnetic field pendulous oscillation, which occurs in induction motors under faulty conditions, is introduced in this paper. This approach enables one to distinguish and classify an unbalanced voltage power supply and machine manufacturing/construction imperfections from an interturn fault. The experimental results for the two case studies of a set of 5-hp and 2-hp induction motors verify the validity of the proposed approach. Moreover, it can be concluded from the experimental results that if the circulating current level in the shorted loop increases beyond the phase current level, an interturn fault can be easily detected using the proposed approach even in the presence of the existence of motor manufacturing imperfection effects. [ABSTRACT FROM AUTHOR]