{'fraction_non_alphanumeric': 0.02478017585931255, 'fraction_numerical': 0.0, 'mean_word_length': 5.695187165775401, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Improved Open-Circuit Airgap Field Model for FSCW-STPM Machines Considering PM-MMF Fluctuation

In this article, we propose an improved analytical model for the fractional-slot concentrated-winding spoke-type permanent-magnet (PM) machines, where the impact of slotting on magnetomotive force (MMF) is elaborately considered. First, the deficiency of the existing MMF-permeance model using Carter's coefficient is discussed. It is found that adopting Carter's coefficient will cause considerable prediction errors in flux density, especially for machines with a small equivalent airgap and considerable PM-MMF fluctuation. Second, an improved analytical model is proposed based on the relative permeance function and a simplified magnetic circuit model. The proposed model enables to predict common electromagnetic performance, such as PM flux density and back electromotive force with higher accuracy. Moreover, the radial forces exerted on the stator teeth can be predicted precisely as well, which is conducive to further vibration analysis. Both the experimental and finite-element analysis results indicate that the proposed model can enhance the characterization capability of the slotting effect and improve the performance prediction accuracy.