Design of Bulk HTS Rotating Machine Using Closed-Circuit Magnetization

High-temperature superconductors (HTS) can provide intensified magnetic flux that makes conventional rotating machines more powerful and provides higher torque density. Especially in HTS rotating machines using bulk superconductors, it is possible to construct a compact rotating machine without supplying excitation current to the field poles during operation because of the strong magnetic flux trapped at the pinning center. However, associated with the conventional magnetization system required to produce strong magnetization, there are problems with complication of mechanical structure and its operation, difference in trapped magnetic flux density due to super-conducting characteristics for practical applications. Specifically, a new technology with high robustness and operability is necessary in order to realize MW-class bulk-type superconducting rotating machines. Our group has devised a closed-circuit magnetization method, which is a new magnetization method based on field-cooled magnetization, for elemental technology to realize an MW-class radial-gap-type bulk superconducting rotating machine. In this paper, we will report on the completion of the basic design of the rotating machine and evaluation of its usefulness with analytical results and prospects. In this paper, electromagnetic analysis is performed via a finite element analysis of the original design. In order to obtain the results of the model prototype of the optimized kW-class design, we have evaluated the two types of HTS rotor structures. Accordingly, we have set a goal to achieve higher torque density than the current superconducting rotating machine.