No abstract

No abstract

A disk-shaped, double stator, induction motor with High Temperature Superconducting (HTS) field coils is proposed in this paper. Copper, typically used in windings of classic machines, limits current density allowed in field coils due to Joule effect losses. Also iron, which is used in magnetic circuits, limits the magnetic flux density obtained in the air gap due to saturation. The application of HTS field coils and iron removal effect in fractional power disk shaped or axial flux motors is analyzed by comparison of two different stator topologies. Twelve HTS field coils made of Bi-2223 (Bi 2 Sr 2 Ca 2 Cu 3 O 1 0) first generation tape, wrapped around a racetrack-shaped nylon core, are assembled. A simple topology was chosen, consisting of six filed coils per semi-stator arranged in the same plane with 60 º displacement. This topology is analyzed theoretically, based on a linear induction motor approach and simulated using a commercial finite elements program, based on the same approach. In order to study the effect of magnetic saturation two stators were built. In the first, the field coils are assembled in steel plates. In the second, the same coils are assembled on nylon plates. The rotor is composed of an aluminum disk assembled on a stainless steel shaft. The HTS coils were cooled by liquid nitrogen (77 K). Simulations, experimental and theoretical results are consistent, showing high space harmonic distortion for the chosen topologies. It is shown that for this type of low power motors operating at this temperature, as iron saturation is not achieved, ferromagnetic materials removal is not a good option. Besides, flux leakage is to high, degrading developed torque.

Abstract. Taking into consideration the development and integration of electrical machines with lower dimensions and higher performance, this paper presents the design and development of a three-phase axial flux disc motor, with 50 Hz frequency supply. It is made with two conventional semi-stators and a rotor, which can be implemented with a conventional aluminum disc or a high temperature-superconducting disc. The analysis of the motor characteristics is done with a 2D commercial finite elements package, being the modeling performed as a linear motor. The obtained results allow concluding that the superconductor motor provides a higher force than the conventional one. The conventional disc motor presents an asynchronous behavior, like a conventional induction motor, while the superconductor motor presents both synchronous and asynchronous behaviors.

No abstract

An equivalent model and electromechanical characteristics for the disk motor was obtained based on the Steinmetz parameters. This paper describes a series of tests conducted on an axial flux motor, equipped with an aluminum rotor disc and an YBCO high temperature superconducting rotor disc, at liquid nitrogen temperature (77 K). The rotating magnetic field was produced by a four-pole, three-phase stator winding, at 50 Hz. At asynchronous permanent regime, Steinmetz-type models are able to describe both motors' behavior. From the performed tests, the parameters of both motors' models were deduced. A variable load was used to obtain both motor's characteristics (conventional and superconducting). Experimental obtained characteristics of both motors are compared with the ones predicted from parameters' calculation. The HTS motor provides high efficiency then the conventional ones.Index Terms-Axial flux disc motor, HTS materials, YBCO.

High temperature superconducting (HTS) machines are recognized to offer several advantageous features when comparing to conventional ones. Amongst these, highlights the decrease in weight and volume of the machines, due to increased current density in conductors or the absence of iron slots' teeth; or the decrease in AC losses and consequent higher efficiency of the machines, even accounting for cryogenics. These concepts have been already demonstrated and some machines have even achieved commercial stage. In this paper, several alternative approaches are applied to electrical motors employing HTS materials. The first one is an all superconducting linear motor, where copper conductors and permanent magnets are replaced by Bi-2223 windings and trapped flux magnets, taking advantage of stable levitation due to flux pinning, higher current densities and higher excitation field. The second is an induction disk motor with Bi-2223 armature, where iron, ironless and hybrid approaches are compared. Finally, an innovative command strategy, consisting of an electronically variable pole pairs' number approach, is applied to a superconducting hysteresis disk motor. All these concepts are being investigated and simulation and experimental results are presented.

Nowadays an economical and environment crisis is felt in the world due to the increasing fuel prices and high CO 2 emissions. This crisis is mostly due to present the transportation system, which uses internal combustion engines. The development and integration of electrical motors with improved electro mechanical characteristics, using high temperature superconductors, can provide a sustainable future replacing the conventional internal combustion motors. An axial type disc motor, with high temperature superconductor (HTS) material has been developed and tested in order to obtain an electrical equivalent circuit based on the experimental results. The tested HTS motor exhibits a conventional hysteresis motor type of behavior, even though the hysteretic phenomena don't have the same principle. The proposed approach allows the description of the equivalent electrical circuit as a conventional hysteresis motor.