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1. Introduction
Concentrated winding permanent magnet machines are used in many applications due to their high torque density, low torque ripple, and high efficiency (El-Refai, 2010; Ben Hamadou et al., 2009). However, they are characterized by high contents of space harmonics in the air-gap MMF distribution. These harmonics lead to the induction of eddy current loss in the PMs.
In Atallah et al. (2000), an analytical model has been developed to predict rotor-induced eddy currents in such machines, and to quantify the effectiveness of circumferentially segmented PMs in reducing the rotor loss. Toda et al. (2004) presented an analysis of the rotor eddy-current loss in modular and conventional topologies of PM machines. Ishak et al. (2005) developed an analytical model for the prediction of eddy-current losses in the rotor magnets of synchronous machines that have a fractional number of slots per pole. The study covered three types of the armature winding arrangement, which are:
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(1) double layer slots;
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(2) single layer slots; and
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(3) single layer slots with the winding wound on wider teeth.
The iron loss were assessed analytically and by time-stepped finite element analysis (FEA). It has been found that these loss could be significant in the three topologies. Amara et al. (2005) developed an analytical approach for predicting the eddy current loss in the magnets of the moving armature of a tubular machine. Recently, Bianchi et al. (Bianchi and Fornasiero, 2009; Bianchi et al., 2009) adopted a straight-lined 2D analytical model for the prediction of the rotor eddy-current losses, considering different topologies of PM synchronous machines.
This paper presents an analytical approach for the prediction of eddy current loss in the PMs of a concentrated winding machine. Based on the armature MMF spectrum, the proposed approach allows, in a first step, the assessment of the eddy current loss in a given PM, then those of the entire PMs are deduced. Compared to FEA-based numerical models, the proposed analytical one gives a rapid estimation of iron losses which makes it simple the sizing and optimization procedures. It could be a powerful tool for the comparison between different topologies of PM machines. Extending the comparison with the model developed in Bianchi and Fornasiero (2009) and Bianchi et al. (2009), one...