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This paper gives an overview of the design, manufacturing and testing of a high‐speed (16,000 rpm and 30 kW) AFPM synchronous machine, which is mounted inside, and as an integral part of, a flywheel. This system will subsequently be used for transient energy storage and ICE operating point optimization in an HEV. The paper focuses on the major design issues, particularly with regard to the high rotational speed, and investigates the loss mechanisms which are apparent therein, e.g. iron losses, rotor losses, and friction losses. The paper describes the high‐speed testing facility and includes measured results, which will be compared to calculated values.

The purpose of this paper is the investigation of eddy currents induced in the axial‐flux permanent‐magnet machine housing by the leakage flux and the introduction of permanent magnets in the steady‐state AC finite‐element analysis and coupling their effects with the transient thermal analysis.

The proposed approach is based on the finite‐element method as well as on using the basic analytical equations. The approach was first applied in the magneto transient analyses. Because of the different physical transient‐time constants, the steady‐state AC analysis coupled with transient thermal should be used.

The permanent magnets in the steady‐state AC analysis coupled with the transient thermal analysis can be simulated by coils with an imposed current of a frequency depending on the number of pole pairs and rotation speed. Using any of the electrically conductive materials for the axial‐flux inner slotless stator permanent‐magnet machine housing should be avoided.

The leakage flux induced by permanent magnets and spreading into the axial‐flux permanent‐machine housing is first defined by using the magneto‐transient finite‐element analysis and further used in the steady‐state AC analysis coupled with the transient thermal analyses, all in 3D. Based on the results of these analyses, the temperature distribution in entire machine is calculated and compared with the measurement results.

The space‐mapping (SM) optimization technique, with its input, implicit or output mapping‐based implementations, provides a basis for computationally efficient engineering optimization. Various algorithms and design optimization problems, related to microwave devices, antennas and electronic circuits, are presented in numerous publications. However, a new application area for SM optimization is currently expanding, i.e. the design of electromechanical actuators. The purpose of this paper is to present an overview of the recent developments.

New algorithm variants and their application to design problems in electromechanics and related fields are briefly summarized.

The paper finds that SM optimization offers a significant speed‐up of the optimization procedures for the design of electromechanical actuators. Its true potential in the area of magnetic systems and actuator design is still rather unexplored.

This overview is complementary to the previous published reviews and shows that the application of SM optimization has also extended to the design of electromechanical devices.

The thermal design of high‐speed electrical machines is a greater challenge in comparison with conventional electrical machines. When designing the machine, the calculated temperatures in all parts should be lower than their critical temperatures. This paper aims to perform thermal analysis for different rotor types according to the level of shield from eddy currents in order to achieve a safe thermal design of the machine.

The machine under study in the paper is a high‐speed permanent magnet (PM) motor designed for speed n=31,500 rpm and power P=130 kW. A thermal‐network method was used for thermal analysis of the machine.

The minimum value of the coolant flow in the air gap that provides an effective cooling of the machine was estimated. The coolant itself is not able to provide an effective cooling of the magnets if they are not shielded from eddy currents.

The results are obtained only by the thermal‐network method. Numerical techniques and practical measurements for comparison and validation of the existing results should be implemented in future.

The paper offers useful practical information when a safe thermal design of a high‐speed PM electrical machine should be performed.

The paper demonstrates how three different design types of a high‐speed PM electrical machine are thermally analysed in order to find out which type fulfils the rigorous thermal criteria. The practical significance of the paper is beneficial for the designers of high‐speed PM electrical machines.

The purpose of this paper is to present novel analytical expressions which describe the 3D magnetic field of arbitrarily magnetized triangular‐shaped charged surfaces. These versatile expressions model that the field of triangular‐shaped permanent magnets (PMs) are very suitable to model skewed slotless machines.

The analytical 3D surface charge method is normally used to provide field expressions for PMs in free space. In this paper, the analytical surface charge integrals are analytically solved for charged right‐triangular surfaces. The resulting field is compared with that obtained by finite element modeling (FEM) and subsequently applied in two examples.

The comparison with FEM shows that the 3D analytical expressions are very accurate and exhibit very low‐numerical noise. These fast‐solving versatile expressions are therefore considered suitable to model triangular‐shaped or polyhedral‐shaped PMs.

The surface charge method assumes that the relative permeability is equal to 1 and therefore soft‐magnetic materials need to be modeled using the method of images. The PMs are assumed to be ideal in terms of homogeneity, magnetization vector, permeability, demagnetization, and geometrical tolerances.

Many applications, such as the subclass of slotless synchronous linear actuators with a skewed PM structure and planar magnetic bearings, are very suitable to incorporate this modeling technique, since it enables the analysis of a variety of performance data.

As an addition to the common 3D analytical field expressions for cuboidal or cylindrical PMs, this paper presents novel expressions for magnets having triangular surfaces.

The aim of this paper is to reduce the evaluations number of the fine model within the output space mapping (OSM) technique in order to reduce their computing time.

In this paper, n-level OSM is proposed and expected to be even faster than the conventional OSM. The proposed algorithm takes advantages of the availability of n models of the device to optimize, each of them representing an optimal trade-off between the model error and its computation time. Models with intermediate characteristics between the coarse and fine models are inserted within the proposed algorithm to reduce the number of evaluations of the consuming time model and then the computing time. The advantages of the algorithm are highlighted on the optimization problem of superconducting magnetic energy storage (SMES).

A major computing time gain equals to three is achieved using the n-level OSM algorithm instead of the conventional OSM technique on the optimization problem of SMES.

The originality of this paper is to investigate several models with different granularities within OSM algorithm in order to reduce its computing time without decreasing the performance of the conventional strategy.

The purpose of this paper is to investigate the use of multidisciplinary optimization (MDO) formulations within space‐mapping techniques in order to reduce their computing time.

The aim of this work is to quantify the interest of using MDO formulations within space mapping techniques. A comparison of three MDO formulations is carried out in a short time by using an analytical model of a safety transformer. This comparison reveals the advantage of two formulations in terms of robustness and computing time among the three MDO formulations. Then, the best formulations are investigated within output space mapping, using both analytical and FE models of the transformer.

A major computing time gain equal to 5.5 is achieved using the Individual Disciplinary Feasibility formulation within the output space‐mapping technique in the case of the safety transformer.

The MultiDisciplinary Feasibility formulation is the common formulation used within space‐mapping technique because it is the most conventional way to perform MDO. The originality of this paper is to investigate the Individual Disciplinary Feasibility formulation within output space‐mapping technique in order to allow the parallelization of calculation and to achieve a major reduction of computing time.

The purpose of this paper is to describe a twofold methodology for evaluating the force between field excitation system and bulk in a magnetic‐levitation device based on high‐temperature‐superconductors (HTS). The paper focuses on two‐dimensional field models for HTS bulks. As far as field analysis is concerned, the finite‐element method in two or three dimensions is used. Alternatively, the conformal mapping approach provides a flexible and accurate calculation tool, useful for the optimization of superconducting bearings.

Powerful mapping algorithms, developed recently for Schwarz‐Christoffel‐like transformations, have proven successful in analyzing the fields, both in the activation and in the operation condition of superconductor devices.

Assuming small displacements of the superconductor sample with respect to the excitation magnets, the force‐displacement curve was obtained for operational field cooling via Schwarz‐Christoffel maps.

The specific theory used is the substitution theorem for magnetic fields, along with its capability to take complex geometries into account, making it possible to model devices for real‐life applications. Using only a scalar potential, the procedure proposed for computing fields proves, in the conformally‐mapped plane, the superposition method already introduced in FEM‐based models.

The purpose of this paper is to present a semi‐analytical modeling technique to describe magnetic fields due to PMs in 3D cylindrical structures. The model is based on 2D Fourier series and is applied to model the magnetic field of checkerboard magnetization patterns for rotary‐linear actuators.

The modeling technique based on Fourier series provides a direct solution of the Poisson and Laplace equation by means of separation of variables and is widely used to describe magnetic fields in electromagnetic devices in 2D coordinate systems. In this paper the magnetic scalar potential is used in the Poisson and Laplace equations.

The magnetic field calculated by the semi‐analytical model is compared with that obtained by Finite Element Modeling and shows excellent agreement. The calculation time of the semi‐analytical model is approximately 60 times shorter than that of finite element analysis.

The method as presented in the paper assumes linear material properties, e.g. the non‐linear B‐H characteristics of iron cannot be taken into account. Furthermore, the structure is assumed to be slotless, that is, stator slots or end‐effects cannot be taken into account.

The semi‐analytical modeling technique is applied to checkerboard magnetization patterns for 2‐DoF actuators in this paper. However, it can be applied to a wide range of slotless cylindrical electromagnetic devices.

As an addition to the common 2D modeling by means of Fourier series, this paper extends the applicability to 3D cylindrical structures. Furthermore, a new checkerboard magnetization is presented which can be used in 2‐DoF rotary linear actuators.

Manifold‐mapping (MM) is an efficient surrogate‐based optimization technique aimed at the acceleration of very time‐consuming design problems. In this paper we present two new variants of the original algorithm that make it applicable to a broader range of optimization scenarios.

The first variant is useful when the optimization constraints are expressed by means of functions that are very expensive to compute. The second variant endows the original scheme with a trust‐region strategy and the result is a much more robust algorithm.

Two practical optimization problems from electromagnetics eventually show that the proposed variants perform efficiently.

The original MM algorithm is extended with two new variants. Therefore, the MM approach is applicable to a much larger set of design situations.