We develop a novel high-temperature superconducting (HTS) induction motor with saddle-shaped HTS armature windings, which adopts the structure with a coreless stator and a conventional squirrel-cage rotor that is aimed to lightweight and higher speed. In this paper, the saddle-shaped HTS armature windings is composed of three layers of coils, of which each layer is arranged in six along circumferential direction. Moreover, the detailed production method of the coil is illustrated. According to the electromagnetic field theory, the electromagnetic characteristic of the newly designed HTS coreless induction motor is investigated including the flux density distribution and the torque ripple under the condition of no-load and rated load. Then, based on the initial geometry model, the arrangement structure of the HTS coils is optimized and analyzed. By optimizing the rotation angle of the HTS coil layer along the circumferential direction, it is found that the magnetic field perpendicular to the tape surface in the optimized shape coils significantly decreases compared with that in the initial shape coils. In addition, it is also noticed that not only the torque ripple becomes smaller, but also the distortion of the air- gap magnetic flux density is improved. Finally, a satisfactory coils arrangement structure model is obtained, which is intended to be utilized for HTS coreless motor.

Large electric superconducting machines are being sought to solve emissions challenges in aircraft and provide a solution to >12 MW wind turbine electricity generation. Superconducting motors with only high temperature superconducting (HTS) armatures can offer advantages of high reliability, high power density, and high efficiency compared with conventional superconducting motors. In this paper, a novel HTS squirrel-cage induction motor is proposed for high speed operation, which adopts the structure of HTS windings with a certain inclination angle in the stator slots. Due to the limitation of curvature radius of superconducting tapes, the pitch of HTS windings can be only set to 1 and adopt the short pitch arrangement structure, which such design details of the HTS motor would ensure the superconducting coils can undertake larger current and reduce AC losses. In order to keep the HTS windings in superconducting state and larger current density, a special fixed cryogenic cooling system below 70 K with the method of gas extraction and decompression, which is made of aramid fiber, has been fabricated and the whole structure of the stator is placed in liquid nitrogen. According to the motor control principles and electromagnetic field theory, the electrical performances of the novel designed stator-HTS motor, which driven by the variable-voltage variable-frequency (VVVF) inverter, are analyzed including the flux density distributions, the torque, the induced electromotive force, losses and efficiency by using the finite element method. Finally, the components of HTS squirrel-cage induction motor have been manufactured according to the designed parameters. Next step, the motor will be assembled and tested.

Aiming to address the computational difficulties caused by the large width ratio of superconducting tapes, especially in calculating the AC losses of 3D superconducting coils, this paper proposes to study the AC loss laws of a 3D model of racetrack superconducting coil using the T – A equation group model. Firstly, the critical current of the superconducting coil is estimated based on the structure of the coil and the technical parameters of superconducting materials used in high-temperature superconducting (HTS) motors. The transmission AC losses of the superconducting coil under different n values, different transmission currents, different frequencies and different coil structure sizes are studied using T – A equations. Finally, the critical current test system and AC loss test system for HTS tapes and coils are set up. The critical current test and AC loss test for HTS tapes and coils are carried out, and the results are compared with those calculated by finite element method. The test results show the reliability of the T – A mathematical model, which can be used as a pre-valuation in engineering applications.

The courses of innovation and entrepreneurship training are proposed by colleges and universities to change the traditional education concepts and cultivate more applied talents. This article takes Nanchang University as an example to introduce the current situation and existing problems of innovative courses in universities. Aiming at these problems, the author puts forward some relevant suggestions from the perspective of teachers and schools in order to improve the teaching quality of innovative courses and explore the educational methods of college students’ innovation and entrepreneurship.