Design and Short-Circuit Analysis of a 1 MW Superconducting Generator for Electric Aircraft

Abstract

High temperature superconducting (HTS) synchronous machines hold significant potential for future electric propulsion systems in aircraft. HTS machines feature larger electromagnetic airgap and smaller reactance than their conventional counterparts, resulting in higher fault currents and instantaneous AC losses in HTS field windings during sudden short circuits at machine terminals. This paper first presents a multi-objective optimization process for a 1 MW, 6000 rpm HTS synchronous generator and compares the performance with and without a rotor back iron. Second, a finite element (FE) model, which couples rotating dynamics, external circuits, and an HTS numerical method based on the T-A formulation, is developed to simulate the characteristics of four short circuit events. The current and AC losses in the HTS field winding under each short-circuit scenario are examined. Based on the results, the design and optimization of an electromagnetic (EM) shield are also discussed. The findings show that the machine with a non-magnetic rotor back iron has higher power density and efficiency. By examining the effect of the rotor EM shield thickness on the field winding's ripple current and the eddy current loss, we found that a 3 mm copper shield is an optimal choice.