Speaker
Description
The distributed electric propulsion system with superconducting synchronous motors with lightweight and high power density is a promising technology to reduce CO2 emissions. REBa2Cu3Oy (RE = Y, Eu, Gd, etc., REBCO) superconducting tapes have an advantage of higher critical current density even in high magnetic field at a liquid nitrogen temperature. Then fully superconducting motors with REBCO tapes have an advantage in power density as compared with partially superconducting motors. However the REBCO superconducting tapes have complicated AC loss properties. In addition, we plan to cool the REBCO superconducting field winding by helium gas in near future for the reduction of windage loss. In the actual situation in the future, hydrogen gas will be adopted as well as the present power generators. As well known, the cooling capacity of gas is not so high as compared with liquid. So it is necessary to reduce the AC loss in the field winding induced due to the variation of applied magnetic field. The magnetic field applied to the field winding is composed of DC field by field winding itself and AC field by armature windings. The AC loss properties of the REBCO superconducting tapes in such a situation have not cleared yet. In this paper, the AC losses in the field winding were investigated in order to find out the optimum winding design from the viewpoint of loss reduction. First the AC loss of REBCO superconducting tapes was measured under DC and AC magnetic fields by the pickup coil method. Next, by making a numerical calculation of magnetic field distribution in a motor operation, the AC losses in field winding were estimated. Finally the optimum winding design was proposed. The details will be presented in MT27.
