Characteristic study and loss reduction strategy of HTS stators for practical realization of fully superconducting HTS motors
李 全, 三澤 慎太郎, 中村 武恒, 北野 紘生, 雨宮 尚之 （京大）； 伊藤 佳孝, 吉川 雅章, 寺澤 俊久 （イムラ材研）； 奥村 暢郎 （アイシン精機）
Abstract:Superconducting motors, characterized with both high performance and high efficiency, are a potential key to develop environmental-friendly automobile systems, to cope with the serious issues such as depletion of fossil fuels and global warming caused by CO2 emissions. This paper is to present our up-to-date outcomes of characteristic study and loss reduction strategy of the HTS stator with 3-phase superconducting windings in a fully superconducting HTS motor. Firstly, based on the nonlinear properties of superconducting windings in the HTS stator, a novel control method for variable-speed driving is developed. Second, the details of a 20 kW fully superconducting HTS motor are presented, including both HTS rotor and HTS stator, on which the characteristic study was carried out. Then, the DC properties of each phase among the 3-phase superconducting windings are studied based on numerical analyses and experimental measurements. The results indicate a set of well balanced 3-phase superconducting windings. Afterwards, the AC properties of the HTS stator are studied by inputting a 3-phase balanced AC voltage. AC losses were measured which show an abnormal result with unequal amounts of losses in each phase. Finally, corresponding discussions are presented for this unusual phenomenon and for the strategy to reduce losses.