Performance Testing of 400 kW-Rated REBCO Superconducting Synchronous Machine in Low-Temperature and Low-Pressure Environments

Aircraft equipment needs to maintain stable operation in low-temperature and low-pressure environments. This study assesses the feasibility of operating a developed machine under such conditions. Rotational tests were conducted in an environment that simulated the conditions required for aircraft-mounted equipment. The synchronous machine was installed in a thermostatic chamber that was set to a temperature of −55 °C and pressure of 11 kPa, which mimics the conditions at an altitude of 15,000 m. The machine demonstrated stable operation at a rotational speed of 180 rpm, with a field current of 50 A and an armature current amplitude of 100 A at a frequency of 3 Hz. The synchronous machine was tested in generator mode at ground level under no-load and three-phase short-circuit conditions to evaluate its rated operation under a normal environment. In the no-load test, the field current and rotational speed were increased from 10 A to 110 A and 100 rpm to 2,500 rpm, respectively, and the maximum line voltage was 590 V. In the three-phase short-circuit test, the U, V, and W phases exhibited maximum short-circuit currents of 490 A with a field current of 45 A and rotational speed of 100 rpm. These results confirm that the synchronous machine operated stably at 2,500 rpm with an output of 250 kW in generator mode. The stable performance of the machine under these conditions suggests its potential for enhancing the efficiency, power density, and reliability of electric propulsion systems in aviation.