Transient Test and AC Loss Study of a Cryogenic Propulsion Unit for All Electric Aircraft

Fangjing Weng,Neville Mcneill,Min Zhang,Abdelrahman Elwakeel,Tian Lan,Weijia Yuan

doi:10.1109/access.2021.3073071

Abstract

This paper reports a pioneering demonstration platform of a cryogenic propulsion unit at liquid nitrogen temperature. A high temperature superconducting (HTS) machine is connected with a cryogenic power rectifier in a generator mode to prove the feasibility of a cryogenic propulsion unit for electric aircraft propulsion applications. Machine operation was carried out with a special focus on the total heat dissipation inside the HTS AC windings. Different types of 2G HTS tapes were tested to provided data for stator coils’ design. The transient operation was carried out to represent a short-circuit failure in one of the power electronic devices. The test shows AC loss performance of the HTS windings using calorimetric method during the short circuit event, indicating the importance of developing protection schemes for the cryogenic propulsion units to prevent damage to the HTS components. The paper provides initial insights into the interaction between superconducting machines and cryogenic power electronics within a cryogenic propulsion unit. It is an important first step to understand and further develop cryogenic propulsion technology for future electric aircraft.

Highlights

To address the environmental impacts of air transportation and achieve long-term sustainability, the aviation industry has called for generation aircraft with reduced emissions [1]–[10]
The aim of this paper is to demonstrate, for the first time, the testing of a cryogenic propulsion unit consisting of an high temperature superconducting (HTS) machine and a cryogenic power rectifier
The normalized transport loss versus normalized transport current measured by the electrical method is shown in Fig. 5, according to our alternating current (AC) power supply’s limit, the frequencies are chosen at 36 Hz and 72 Hz, and the results are shown by normalized AC loss (Joule/cycle/m), our results indicate that the normalized transport AC loss of both coils are frequency independent

Summary

INTRODUCTION

F. Weng et al.: Transient Test and AC Loss Study of a Cryogenic Propulsion Unit for All Electric Aircraft increase the power density of electrical machines by up to 400% [14], [15]. Weng et al.: Transient Test and AC Loss Study of a Cryogenic Propulsion Unit for All Electric Aircraft increase the power density of electrical machines by up to 400% [14], [15] They are the key technology to enable aviation electrical propulsion [5]. Considering the efficiency of the cryogenicrefrigerator, a closed loop cooling system would be used to ensure reliability and increase the efficiency of the cryogenic cooling systems [8], [16], [17] This means power electronic devices would run in cryogenic operating temperature (25 - 77 K).

A NOVEL CRYOGENIC PROPULSION TESTING PLATFORM

Findings

FUTURE WORK AND CONCLUSION