Analytical sub-domain model for predicting open-circuit field of permanent magnet vernier machine accounting for tooth tips

Abstract

Purpose

Due to high electromagnetic torque at low speed, vernier machines are suitable for direct-drive applications such as electric vehicles and wind power generators. The purpose of this paper is to present an exact sub-domain model for analytically predicting the open-circuit magnetic field of permanent magnet vernier machine (PMVM) including tooth tips. The entire field domain is divided into five regions, viz. magnets, air gap, slot openings, slots, and flux-modulation pole slots (FMPs). The model accounts for the influence of interaction between PMs, FMPs and slots, and radial/parallel magnetization.

Design/methodology/approach

Magnetic field distributions for slot and air-gap, flux linkage, back-EMF and cogging torque waveforms are obtained from the analytical method and validated by finite element analysis (FEA).

Findings

It is found that the developed sub-domain model including tooth tips is very accurate and is applicable to PMVM having any combination of slots/FMPs/PMs.

Originality/value

The main contributions include: accurate sub-domain model for PMVM is proposed for open-circuit including tooth-tip which cannot be accounted for in literature; the model accounts the interaction between flux modulation pole (FMP) and slot; developed sub-domain model is accurate and applicable to any slot/FMP/PM combinations; and it has investigated the influence of FMP/slot opening width/height on cogging torque.

Citation

Oner, Y., Zhu, Z.Q., Wu, L.J. and Ge, X. (2016), "Analytical sub-domain model for predicting open-circuit field of permanent magnet vernier machine accounting for tooth tips", COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Vol. 35 No. 2, pp. 624-640. https://doi.org/10.1108/COMPEL-11-2015-0422