ラジアル型超電導磁気軸受におけるロータ降下の抑制

Abstract

Superconducting flywheel energy storage systems (SFESS) using superconducting magnetic bearings (SMBs) have been studied to contribute to daily load leveling. It is known that the levitation force of SMBs used for SFESS varies with time due to flux creep. In providing noncontact support to the whole weight of the SFESS rotor using a SMB, it should be noted that a decline in the levitation force of the bearing would result in rotor over time. Accordingly, an important consideration in providing long-time noncontact support to the rotor of an SFESS by a SMB is to control and minimize rotor descent. Among promising techniques to control descent are a method using the temperature characteristics of superconductors (a supercooling method), a method using the hysteretic characteristics of superconductors (a pre-load method), and a combination of these two methods. A study was conducted on these rotor descent control methods to examine their respective effects. In this study, a series of tests was carried out on the control methods using a radial superconducting magnetic bearing of the 126mm diameter class, The test results were compared and analyzed to find major characteristics and effects of the three rotor descent control methods as applied to the radial SMB of an SFESS.