The reduction of emission is a key goals for the aviation industry. One enabling technology to achieve this goal, could be the transition from conventional gas turbines to hybrid-electric drive trains. However, the requirements concerning weight and efficiency that come from applications like short range aircraft are significantly higher than what state-of-the-art technology can offer. A key technology that potentially allows to achieve the necessary power and volume densities for rotating electric machines is superconductivity. In this paper we present the concept of a high power density generator that matches the speed of typical airborne turbines in its power class. The design is based on studies that cover topology selection and further electromagnetic, HTS, thermal, structural and cryogenics aspects. All domains were analyzed by means of analytical sizing and 2D/3D FEA modeling. With the help of our digital twin that is a synthesis of these models, we can demonstrate for the first time that under realistic assumptions on material properties gravimetric power densities beyond 20 kW kg−1 can be achieved.

No abstract

This paper presents a semi-physical parameter identification for a recently proposed enhanced iron-loss formula, the IEM-Formula. Measurements are performed on a standardized Epstein frame by the conventional field-metric method under sinusoidal magnetic flux densities up to high magnitudes and frequencies. Quasi-static losses are identified on the one hand by point-by-point dc-measurements using a flux-meter and on the other hand by extrapolating higher frequency measurements to dc magnetization using the statistical loss-separation theory (Jacobs et al., “Magnetic material optimization for hybrid vehicle PMSM drives,” in Inductica Conference, CD-Rom, Chicago/USA, 2009). Utilizing this material information, possibilities to identify the parameter of the IEM-Formula are analyzed. Along with this, the importance of excess losses in present-day non-grain oriented Fe-Si laminations is investigated. In conclusion, the calculated losses are compared to the measured losses.

No abstract

No abstract

PurposeA fundamental disadvantage of three‐dimensional finite element (FE) simulations is high computational cost when compared to two‐dimensional models. The purpose of this paper is to present an approach to minimize the computation time by achieving the same simulation accuracy.Design/methodology/approachThe applied approach for avoiding high computational cost is the multi‐slice method. This paper presents the adoption of this method to a tubular linear motor.FindingsIt is demonstrated that the multi‐slice method is applicable for tubular linear motors. Furthermore, the number of slices and thereby computation time is minimized at the same accuracy of the simulation results.Practical implicationsThe results of this paper offer a faster computation of skewed linear motors. At this juncture, the results are independent from the deployed FE solver.Originality/valueThe methods developed and proved permit a faster and more accurate design of tubular linear motors.

Purpose -The paper proposes presenting a transient 3D-FE computation approach of the eddy current losses in the rail and the flux concentrating pieces of a magnetically levitated conveyor vehicle. Design/methodology/approach -The calculation process is started with a coarse mesh in order to reduce computation time without losing accuracy. Then mesh refinement iterations are performed, based on the estimation of the discretisation error. The results of the post processing are the levitation force, the braking force and the eddy current losses. Findings -The paper finds that by means of adaptive mesh refinement, the error is significantly reduced with a minimum increase of computation time. The hot spots of eddy current losses can be localised by visualizing the eddy current density. At nominal speed, especially the huge amount of eddy current losses in the flux concentrating pieces must be considered during the development process.Research limitations/implications -For further development, the linear motor will be modified with the results of FE computations to reduce eddy current losses. Therefore, different materials and a variation of geometry will be considered. Practical implications -Magnetically levitated systems excite eddy current losses instead of bearing losses. These losses must be taken into account when developing the drive. Originality/value -It proposes a transient 3D-FE approach for computing eddy current losses accurately with a minimum increase of computation time.

No abstract