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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. [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate the optimal design of a 120 W outer‐rotor permanent magnet synchronous machine for air‐conditioning applications to reduce the electricity consumption and machine costs. To this end, a 2‐D analytical magnetic model, combined with a teaching–learning based optimisation algorithm is employed. The objectives are to simultaneously maximise the machine efficiency and minimise the material cost. Constraints such as the required output torque, predefined machine volume, maximum allowable torque ripple and unbalanced magnetic force and limitations to avoid iron core magnetic saturation are imposed simultaneously. To find the flux density in iron parts, a new method based on the subdomain technique has been presented. To evaluate the analytical model in terms of accuracy and speed, the results of the 2‐D analytical approach are compared with those of the 2‐D and 3‐D linear/non‐linear finite element method. Finally, a prototype of the optimised machine is fabricated and the superiority of the presented approach is demonstrated. [ABSTRACT FROM AUTHOR]

This paper deals with the design and test of a contactless capacitive power converter operating at a frequency of 1 MHz, intended to supply the excitation winding of an 80 kW wound rotor synchronous machine. The methodology integrates the electromagnetic design of the rotor and its impact on the different parameters of the converter. To verify the validity of the concept, a first prototype was built by using surface-mounted capacitors grounded on the structure of a 1 MHz Class E resonant power converter. Then, a more representative capacitive contactless coupler was designed and implemented. Comparisons between simulation and experimental results have shown the limits of the proposed contactless power transmission. Special attention was paid on losses and efficiency which are crucial for this application. [ABSTRACT FROM AUTHOR]