<b>Development of a Superconducting Magnetic Bearing Capable of Supporting Large Loads in a Flywheel Energy Storage System for Railway Application</b>

Abstract

Application of the flywheel energy storage system (FESS) using high temperature superconducting magnetic bearings (SMB) has been demonstrated at the Komekurayama photovoltaic power plant located in Yamanashi Prefecture. In order for the FESS to be applied to railways as a system able to prevent cancellation of regenerative braking its storage capacity must be increased. Therefore, levitation force tests up to 158 kN and tests to determine the creep characteristics of the levitation force were carried out to verify the margin in SMB levitation force. Furthermore, to evaluate long-term reliability and durability of the levitation and rotation characteristics of the SMB against repeated change in rotation speed, new SMB test apparatus capable of simultaneously testing both the levitating and rotating states of the SMB is being developed.

Stabilization of a Magnetic Repulsive Levitation Flywheel System Using a High-Efficiency Superconducting Magnetic Bearing

“…The radial and axial restoring forces of the SMBs produced in this research were compared with those of models in previous studies [5]. Figure 10 shows the structure of the SMB that we created.…”

“…Figure 10 shows the structure of the SMB that we created. The HTS used in this SMB [5] had the same outer and inner diameters as those used in this study.…”

“…Figure 10 shows the structure of the SMB that we created. The HTS used in this SMB [5] had the same outer and inner diameters as those used in this study. Table 3 shows the results of a comparison between the restoring force of each axis, the total volume of high-temperature superconductors (HTS) used, and the total volume of permanent magnets (PM) used.…”

“…Rotational loss occurs in bearings, such as metal bearings and rolling bearings, which are subject to contact, and when used for a long time, their function is deteriorated by abrasion. The SMB generates a restoring force along all axes without the necessity of control; it is not necessary to lubricate it, and the rolling loss can be made extremely low [5]. Furthermore, it is possible to realize a bearing with a high rigidity only in a specific direction and a soft bearing in another direction.…”

Exploration on the application of a new type of superconducting energy storage for regenerative braking in urban rail transit

“…Therefore, there are few superconducting magnetic bearings with and permanent magnet in the application of flywheel-based RBS at present. On the other hand, the attempts are currently underway to develop a superconducting magnetic bearing with high-temperature superconducting coils and bulks for flywheel-based RBS [41,42]. The public data showed that the superconducting magnetic bearing can provide a stable levitation of 158 kN, 7% over the target value, and its levitation force decrease was 1.3% for 8 h. It was reported that the levitation height of the flywheel can be kept constant by controlling the current applied to the superconducting coils if the flux creep characteristics are at this level [43].…”