Electromagnetic fields and thrust-ripples calculation for segmented-secondary linear flux-switching motors AQ:au Monir Sadat Hosseini and Hamid Javadi The School of Electrical Engineering, College of Engineering, University of Shahid Beheshti, Tehran, Iran, and Sadegh Vaez-Zadeh The School of Electrical and Computer Engineering, University of Tehran, Tehran, Iran and Center of Excellence on Applied Electromagnetic Systems, University of Tehran, Tehran, Iran Abstract Purpose – This paper aims to investigate analytical electromagnetic fields and thrust ripples representation of linear flux-switching motors with simple modulated secondary referred as segmented secondary linear flux-switching motor (SSLFSM). Design/methodology/approach – SSLFSMs are applicable to transportation systems like Maglev due to their simple and consequently low-cost secondary structures and high force density. However, they have high thrust ripples that deteriorate a smooth motion in rail transportation systems. Therefore, derivation of accurate analytical models for thrust ripples minimization of the motor is essential, which is absent in the literature. In this paper, a two-dimensional analytical model is developed for this motor. The model is based on transfer relations and Fourier theory used for solving a two-dimensional boundary value problem. Certain model regions are determined by considering actual machine structure and observing specific rules. Analytical solution of Maxwell and Poison equations are then obtained in the regions. Finding – Using the presented modeling method, the airgap electromagnetic field distribution and developed thrust of the motor are calculated for different positions of the motor as well as its thrust ripples. They are verified by the results obtained from finite element method. Also, the analytical results are compared with the presented experimental results. Originality/value – This paper has analytically presented the airgap electromagnetic field distribution, thrust and thrust ripples of the SSLFSMs. This modeling is essential in thrust ripples minimization of the motor. Keywords Electromagnetic fields, Applied electromagnetism, Finite element method, Magnetic force, Boundary value problems, Linear machine Paper type Research paper 1. Introduction A new type of linear flux-switching motors (LFSMs) referred as segmented secondary linear flux-switching motor (SSLFSM) is developed for rail transportation applications (Abdollahi and Vaez-Zadeh, 2014). SSLFSMs inherit most merits of LFSMs such as simple and robust structure of secondary and high force density (Shen et al., 2018; Cao et al., 2018). However, This work was supported by ALBORZ-Province-Power-Distribution-Company. J_ID: COMPEL ART NO: 10.1108/COMPEL-04-2018-0177 Date: 26-September-18 Page: 1 Total Pages: 25 4/Color Figure(s) ARTTYPE="R ID: sadasivans Time: 07:49 I Path: //mbnas01.cadmus.com/home$/40333$/EM-COMP180160 Thrust-ripples calculation Received 12 April 2018 Revised 13 June 2018 1 September 2018 Accepted 7 September 2018 COMPEL - The international journal for computation and mathematics in electrical and electronic engineering © Emerald Publishing Limited 0332-1649 DOI 10.1108/COMPEL-04-2018-0177 The current issue and full text archive of this journal is available on Emerald Insight at: www.emeraldinsight.com/0332-1649.htm