The paper proposes a fast dynamic mathematical model to evaluate the performances of saturated permanent magnet synchronous machines (PMSMs) under stator winding's inter‐turn fault. The parameters of the model can be determined using only manufacturer's data of the healthy machine. Two surface mounted PMSMs have been considered to investigate the validity of the proposed approach; with distributed and concentrated winding. It has been shown that the proposed model predicts the fault current with a reasonable accuracy compared with the non‐linear finite elements analyses and to the experimental results. This model can be incorporated in a global simulation environment of power electronic of electrical device since the computation time is very short.

Purpose: The purpose of this paper is to develop a rapid and realistic modelling approach for the design and characterization of high temperature superconducting (HTS) coils and windings carrying DC currents. Indeed, the strong dependence of the electromagnetic properties of such materials on the magnetic field makes the design and characterization of HTS systems a delicate operation where local quantities have to be evaluated. Design/methodology/approach: A volume integral modelling approach has been developed taking into account the electric nonlinearity of the HTS material which is represented by power law. The variations of the characteristic quantities of the HTS (critical current density and power law exponent) with the magnetic flux density are also taken into account by using Kim’s law. The volume integral modelling allows to model only the active parts of the system and thus to overcome the difficulties linked to the multiscale dimensions. Findings: The model has been tested in a case study in which simulation results were compared to measurements and to finite element analysis. A good agreement was found which validates the model as a rapid and efficient tool for HTS coils and windings design and modelling. Practical implications: HTS coils are important elements of emerging superconducting devices which require a high level of reliability, such as generators or motors. The proposed approach is interesting to speed up the design and optimization procedures of such systems. Originality/value: Advanced structures of the basic elements have been used in the volume integral modelling, which results in a considerable gain in computation time and in memory-space saving while keeping a high level of precision and realism of the modelling, which has been verified experimentally.

In this paper, we propose a method to calculate the magnetic field in flux concentration superconducting magnetic coupling (FCSMC) with rectangular permanent magnets (PMs). The inner rotor is composed of rectangular PMs, and the external rotor is made of high-temperature superconducting coils supplied by dc current. First, an exact 2-D analytical computation is developed in polar coordinates for calculating the magnetic field distribution in FCSMC with sector PMs having the same volume as the rectangular PMs. The model is validated by finite-element computations. The analytical model is then used to predict the performances of FCSMC. The electric loadability of the FCSMC is determined by considering the dependence of the critical current versus the flux density distribution. A parametric study showed that the analytical model can predict the torque with reasonable precision. Therefore, this model can be used for optimization purposes where reductions in computation time are needed.

The IMIA Yearbook of Medical Informatics appears as a non-profit publication of IMIA

This paper presents the detailed design, construction and tests of a protype iron-free MRI-compatible electromagnetic actuator. The originality of this proposal lies in the use of the homogeneous static magnetic field B₀, present in the MRI bore, to ensure the electromechanical energy conversion. The armature is composed of three rectangular coils in a three-phase arrangement, which makes the actuator very light-weight and compact. The operating principle is that of an AC synchronous motor with a rotating armature. In order to design the actuator, a 3D analytical electromagnetic model is developed to predict the magnetic field produced by the armature winding. Then, a 3D finite element (FE) computation is performed to validate the analytically calculated magnetic field. The developed analytical model is then inserted into an optimization routine based on Genetic Algorithms (GAs) to obtain the prototype dimensions to be realized. Finally, the prototype is constructed and tested inside an MRI research scanner. The results indicate that the reduction in the Signal-to-Noise Ratio (SNR) and the geometrical distortion are less than 5% when the actuator is powered with a current of 10 times the rated one and when it is located very close to the subject to be imaged.