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We proposed a non-empirical self-organizing design method to obtain a unique stator structure for a high-temperature superconducting induction/synchronous machine. The method starts from a line current model with an approximately ideal sinusoidal distribution of the air-gap magnetic field. It keeps increasing the cross-sectional area of the windings under appropriate constraints to achieve a model with realistic current density. In this work, we applied this method to design a 25 kW-class high-temperature superconducting induction/synchronous motor. In the model, each slot has three-phase windings with different areas representing different numbers of turns. The width and height of the two slots are different for each pole and phase. The results demonstrated that the self-organizing design method significantly suppressed the torque ripple of the motor and reduced the high-order harmonics. The self-organizing windings are equivalent to a short-pitching configuration, which produce a more sinusoidal air-gap flux density than windings in general design. Reducing torque ripple to the lowest possible level facilitates the practical use of superconducting machines for transportation applications.

Superconductors can help electric machines achieve extremely high torque and power densities. However, operational instability is still a severe challenge for most superconducting electric machines. This paper proposes a novel dual-rotor hybrid excitation variable flux synchronous motor (DRHE-VFPM) suitable for applications with high safety requirements. The primary characteristic is using series-connected permanent magnet (PM) and High-temperature superconducting (HTS) magnet as the rotor's flux sources. These two magnets are on different rotors and steadily excited by each other through armature slots, improving several critical characteristics of the superconducting motor. First, the new electromagnetic topology can avoid severe quench accidents. At normal operation, the PM and HTS rotors can produce a large total electromagnetic torque. When the HTS magnets are damaged by the overtemperature or the mechanical shocks, the motor can still use the PM rotor to generate continuous torque instead of sudden interruption. Secondly, because an excessively strong rotor field will limit the speed, the variable flux density of the HTS magnet allows fuller use of voltage to extend the speed range and improve the power density. Moreover, the main magnetic circuit of the motor changes significantly under different operating states, which is analyzed theoretically in detail.

This paper presents the design of a high-efficiency high power-density traction chain, based on an original high-speed machine concept powered by an innovative power converter, featuring built-in voltage boosting. The input power source is a 60 V battery. The inverter is designed with hybrid semiconductor technology: silicon on the input (low-voltage) side and silicon carbide on the output (higher-voltage) side. The switching frequency of the primary and secondary side switches can be set independently for best efficiency and electro-magnetic signature. The paper includes the detailed design of magnetic components enabling dual switching frequency operation and reduction of current stress in semiconductors and capacitors by means of interleaved cross-coupled inductance power cells. Preliminary prototype development and experimental test results are also discussed.