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This paper presents three analytical techniques for 3D modeling and analysis of coreless stator axial flux permanent-magnet (CS-AFPM) machines under no-load condition. Quasi 3D analytical model based on Hague’s solution, magnetic equivalent circuit (MEC) model, and analytical model based on Fourier-Bessel series are used to calculate the components of air-gap magnetic flux density. In quasi 3D analytical model, the 3D geometry of CS-AFPM machine is transformed into the 2D geometries in different radii. Hague’s solution is used to calculate the tangential and axial components of air-gap flux density in corresponding radius. The law of superposition is then used to calculate the flux-linkage of stator phase. In the MEC model, the non-linear permeance network is used to calculate the axial component of air-gap flux density while considering the curvature effect, the fringing effect, and the leakage magnetic fluxes. In the proposed 3D analytical model, all components of air-gap flux density are calculated while considering the edge effect, the curvature effect, fringing and leakage fluxes, the magnetic saturation, and the skewed PMs. In final, the accuracy and capabilities of these techniques are verified through comparing with corresponding results obtained from 3D finite element method (FEM) and the experiment set-up.

Permanent magnet eddy current couplers (PMECCs) have the characteristics of contactless torque transmission, removal of torque ripple, smooth dynamic process, and adjustable speed, and can be used as couplings, dampers, brakes, and speed governors. Their applications in industry, vehicles, and energy fields are gradually expanding. At the same time, the requirements for the torque density and dynamic performance of PMECCs are increasing. Therefore, a large amount of research work has focused on the fast and accurate modeling, design, and optimization of PMECCs. This paper provides a survey on the development of PMECCs technology. The main topics include the structure and classification of PMECCs, modeling methods, loss and heat transfer analysis modeling, and optimization design. In addition, this paper shows the future trends of PMECCs research. All the highlighted insights and suggestions of this review will hopefully lead to increasing efforts toward the model’s construction and the optimal design of PMECCs for future applications.

Purpose The aim of this study is to investigate the implementation of the sliding-line technique (SLT) in a generic two-dimensional (2D) nonlinear adaptive magnetic equivalent circuit (MEC) model predicting the electromagnetic force evolution of a linear bistable electromagnetic actuator technology. Design/methodology/approach The developed MEC model considers the saturation effect and the auto-adjustability of the spatial discretisation. The connection between static and mobile zones is ensured by an approach known as “air-gap sliding-line technique”, which is widely used for rotary electric motor models. To the best of the author’s knowledge, that is the first time that the SLT is implemented on an electromagnetic structure with linear motion. Findings It was found that, in case of a linear actuator with a relatively small working stroke, the implementation of the SLT could lead to some non-negligible inaccuracies. Originality/value To solve the above-mentioned problem, it was proposed to investigate the implementation of a single SLT vs double SLT. The results of the MEC models were compared with the 2D finite-element analysis (FEA) as well as with the experimental test results. The developed semi-analytical models can be easily adapted to other topologies of linear electromagnetic machines.

To overcome the large power consumption, the braking torque heat recession, and installation difficulties for trailers of eddy current retarder (ECR), a novel self-excited, liquid-cooled, and bridge integrated retarder (SLB-EMR) is proposed in this paper. The structure and work principle of the SLB-EMR are described particularly. Based on the magnetic equivalent circuit (MEC) method, an analytical model of the eddy current braking torque considering magnetic flux leakage and end effect is established. The power generation and braking performance of the SLB-EMR are predicted by the finite element analysis (FEA). We carried out tests for the eddy current braking torque, the heat-fade of braking torque, the no-load loss torque, and natural characteristics of the SLB-EMR respectively. The test results showed that the eddy current braking torque reached 2592 N·m at 1000 r/min. The braking torque declined by 15.5 % after the braking 12 min continuously. The analytical model of eddy current braking torque, and FEA model of the generator and eddy current brake were verified by the test. Compared with the ECR, the SLB-EMR had no-power consumption and low head-fade.

This paper presents a novel technique for synchronous reluctance machines model (SynRMs). The model can be used in both healthy and faulty situations with phase-to-phase fault. The machine properties such as the number of poles and slots, as well as rotor and stator dimension, can be selected arbitrarily in the proposed model. Therefore, various SynRMs with selective properties can be modeled by the proposed method. Considering the nonlinear magnetic equivalent circuit, the healthy and faulty saturable machine with phase-to-phase fault between various windings is also studied. Validation is performed by finite-element method (FEM). Regarding the performed validation, very shorter processing time is obtained compared to FEM.

This paper presents a rigorous design and optimization of an axial flux microelectromechanical systems (MEMS) brushless dc (BLDC) micromotor with dual rotor improving both efficiency and power density with an external diameter of only around 10 mm. The stator is made of two layers of windings by MEMS technology. The rotor is developed by film permanent magnets assembled over the rotor yoke. The characteristics of the MEMS micromotor are analyzed and modeled through a 3-D magnetic equivalent circuit (MEC) taking the leakage flux and fringing effect into account. Such a model yields a relatively accurate prediction of the flux in the air gap, back electromotive force (EMF) and electromagnetic torque, whilst being computationally efficient. Based on 3-D MEC model the multi-objective firefly algorithm (MOFA) is developed for the optimal design of this special machine. Both 3-D finite element (FE) simulation and experiments are employed to validate the MEC model and MOFA optimization design.