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Electrical machines with high-temperature superconducting (HTS) armature windings can benefit from high power density and efficiency. Furthermore, by using permanent magnets (PM) on the rotor, the cryogenic system can be significantly simplified compared with the fully superconducting (SC) machines or the machines with SC field windings. Compared with the conventional electrical machines, the performance of machines with HTS armature windings can be more sensitive to the design parameters due to the interaction between the operating current and the flux density. In this article, the influence of stator geometry on the machine with HTS armature windings and PM rotor is investigated. By considering the interaction between the operating current and the flux density, an iteration procedure for calculating the operating current of the HTS armature windings is proposed. A 10-MW surface-mounted PM wind power generator with HTS armature windings is studied by the finite element analysis. It is found that machines with different coil angle have different behaviors when changing the tooth width and the dimensions of tooth tips, which is different from conventional electrical machines. A new design and optimization method is then developed. Finally, the optimal design is identified with global optimization. [ABSTRACT FROM AUTHOR]

This paper compares the short-circuit performance of superconducting (SC) generators with three different topologies, i.e. iron-cored stator and rotor, iron-cored stator and air-cored rotor, and air-cored stator and rotor. The analysis is based on three-phase short-circuit fault, and finite element analysis is used for simulation. Following the introduction of specifications of generators, the short-circuit performances of different topologies are analysed and compared, with the field winding excited by voltage and current excitation sources, respectively. It shows that the short-circuit performance can be improved by limiting the field current. [ABSTRACT FROM AUTHOR]

The performance improvement of using grain-oriented electrical steels (GOES) in the stator of PM fractional-slot modular machines is analysed in this study. Several models using a finite element tool are examined and it is concluded the techniques used in the actual software are not accurate for simulating anisotropic behaviour. Consequently, a simplified yet accurate modelling technique is proposed to simulate the performance of this type of electrical machines equipped with GOES. The advantages as well as the drawbacks of using GOES on the electromagnetic performance are investigated for different pole/slot combinations. It is concluded that the use of GOES is beneficial from an electromagnetic point of view mainly due to an increase on the radial component of the airgap flux density. [ABSTRACT FROM AUTHOR]

Flux-switching permanent-magnet (FSPM) brushless machines have emerged as an attractive machine type by virtue of their high torque densities, simple and robust rotor structure, and the fact that permanent magnets and coils are both located on the stator. Both 2-D and 3-D finite element analyses are employed to compare the performance of a conventional all poles wound (double-layer winding) topology with that of three modular alternate poles wound (single-layer winding) topologies, in terms of output torque, flux-linkage, back EMF, and inductances. It is shown that the FSPM machine can be designed in this way without incurring a significant performance penalty, but that some degree of rotor skewing or a variation in stator and rotor pole combination may be required in order to maintain a sinusoidal back-EMF waveform and reduce the torque ripple. Experimental validation is reported for both conventional all poles wound and alternate poles wound FSPM machine topologies. [ABSTRACT FROM AUTHOR]