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This paper deals with a novel multiphase permanent-magnet (PM) machine drive to enhance drivetrain availability in electric traction applications. It describes the development of new winding configurations for six-phase PM brushless machines with 18 slots and eight poles, which eliminate and/or reduce undesirable space harmonics in the stator magnetomotive force. In addition to improved power/torque density and efficiency with a reduction in eddy current loss in rotor PMs and copper loss in end-windings, the developed winding configuration also enhances availability of drivetrain, in a variety of applications requiring a degree of fault tolerance, by employing it as two independent three-phase windings in a six-phase interior-PM machine, which is designed and optimized for a given set of specifications for an electric vehicle, under thermal, electrical, and volumetric constraints. This paper also describes the design and development of a six-phase inverter with independent control for both sets of three-phase windings. The designs of the motor and the inverter are validated by a series of preliminary tests on the prototype machine drive. [ABSTRACT FROM AUTHOR]

A 6-phase fractional-slot-per-pole-per-phase interior permanent magnet (IPM) machine having a novel topology of 18-slot, 8-pole and a 6-phase, 48-slot, 8-pole IPM with distributed windings, both designed for a segment-A electric vehicle, are assessed for the risk of partial irreversible demagnetization under various fault conditions. This paper describes a more accurate approach of demagnetization assessment based on 2-D transient finite-element analysis. It is shown that due to the presence of low-order space harmonics in the fractional-slot IPM machine, the demagnetization risks across all pole pairs are different. Compared with the distributed wound machine, the fraction-slot machine is less vulnerable to demagnetization due to relatively high winding inductance, although its demagnetized regions are not uniform in each pole. It is also shown that although the demagnetizing current of one 3-phase short-circuit (SC) is greater than that of 6-phase SC, the resultant demagnetization risk is lower than that of 6-phase SC in the fractional-slotmachine. [ABSTRACT FROM AUTHOR]

The paper is concerned with new winding configurations and associated pole-slot combinations for permanent magnet (PM) machines that lead to improved performance and facilitate cost reduction. Compared to the current state of the art, the salient feature of the proposed designs is elimination and/or reduction of undesirable space harmonics which result from the existing fractional-slot per phase per pole permanent magnet machines with concentric windings. This will bring the benefits of significant reduction of the eddy current loss in the rotor permanent magnets, short end-winding and hence reduced copper loss and copper usage, increased power/torque density, reduction in manufacturing cost, and improved energy efficiency. Although the proposed technique is primarily aimed for brushless permanent magnet machines, it is also applicable to synchronous reluctance machines, induction machines and synchronous wound field machines. The proposed technique is applied to the design of an interior mounted permanent magnet machine for electric vehicle traction applications, and demonstrated by the measurements on a prototype machine. [ABSTRACT FROM PUBLISHER]