Comparison of force density of various superconducting linear motor types considering numerically evaluated AC losses

This paper presents a comparison of the force density of four types of superconducting linear motors, taking into account the AC losses. The losses are evaluated by finite element models in which several methods to reduce model complexity are combined to achieve a low computation time. A parametric search is performed to determine the maximum achievable force density of all motor types, in which the operating temperature, geometric parameters, and peak current through the superconducting coils are varied. Results show the optimum number of turns for each motor type, and that a force density around 2500 N/dm3 can be achieved by all four motor types at 20 K

Finite element model simplification methods for stacks of superconducting tapes

This paper presents a simplification method for finite element models for the calculation of AC losses in stacks of superconducting tapes. A fast and accurate model of these losses can be exploited in the design of large-scale superconducting applications, where the coils are represented as stacks of tapes in 2D models. The simplification method aggregates the superconducting, substrate, and copper layers of several windings of the superconducting tape to form bulk elements. The resulting model is able to evaluate the AC losses in the superconducting layer faster than the full model. The accuracy of the proposed method and decrease in computation time are shown.\u3cbr/\u3

AC losses in HTS coils for high-frequency and non-sinusoidal currents

AC losses in racetrack coils that are wound of YBCO tapes are measured for sinusoidal and non-sinusoidal transport currents with fundamental frequencies up to 1 kHz. An electrical method to measure losses for non-sinusoidal currents is developed for this purpose. The measured losses are compared to the losses calculated by 2D finite element models with power-law material models. The frequency and waveform-dependency of the measured losses are shown and compared to the results of the models over a wide range of frequencies and waveforms. Finally, it is shown that the finite element models can accurately predict AC losses resulting from non-sinusoidal transport currents as are present in highly dynamic motors with AC armature coils

Finite element model simplification methods for stacks of superconducting tapes

This paper presents an analysis of new and existing model simplification methods for the calculation of AC losses in stacks of superconducting tapes using finite element methods. A fast and accurate model of these losses can be exploited in the design of large-scale superconducting applications, where stacks of tapes are a 2D representation of the coils

Modeling and comparison of superconducting linear actuators for highly dynamic motion

This paper presents a numerical modeling method for AC losses in highly dynamic linear actuators with high temperature superconducting (HTS) tapes. The AC losses and generated force of two actuators, with different placement of the cryostats, are compared. In these actuators, the main loss component in the superconducting tapes are hysteresis losses, which result from both the non-sinusoidal phase currents and movement of the permanent magnets. The modeling method, based on the H-formulation of the magnetic fields, takes into account permanent magnetization and movement of permanent magnets. Calculated losses as function of the peak phase current of both superconducting actuators are compared to those of an equivalent non-cryogenic actuator

Comparison of force density of various superconducting linear motor types considering numerically evaluated AC losses

This paper presents a comparison of the force density of four types of superconducting linear motors, taking into account the AC losses. The losses are evaluated by finite element models in which several methods to reduce model complexity are combined to achieve a low computation time. A parametric search is performed to determine the maximum achievable force density of all motor types, in which the operating temperature, geometric parameters, and peak current through the superconducting coils are varied. Results show the optimum number of turns for each motor type, and that a force density around 2500 N/dm3 can be achieved by all four motor types at 20 K

Trends in superconducting linear electric machines

\u3cp\u3eSuperconductivity is a state of matter that allows a constant flow of electrical current with little to no dissipation, provided that the working temperature T, applied magnetic field B, and current I are below a critical surface in a (T, B, I) space. The development of superconducting tapes and bulk materials has allowed the development of superconducting electrical devices that can outperform their counterparts made with copper wires. In this paper we introduce the substantial characteristics of superconductors and examine several applications of superconducting linear machines and their most recent developments. A classification of the machine design is given based on the use of superconducting DC or AC coils, bulk or stacked tapes.\u3c/p\u3

Requirements for 3-D magnetostriction measurement instruments

This paper concerns the requirement analysis and implementation of a measurement instrument, which can identify the 3-D magnetostriction strain. To measure magnetostriction, a high-accuracy magnetic flux density and strain measurement are required, while the mechanical stress in the sample is minimized. The full block tester is proposed as a measurement instrument. In this instrument, homogeneity of flux density within the measured sample and the strain measurement resolution are sufficient, but stress caused by magnetic forces is higher than required