Design Method of Low-Loss Partially High-Temperature Superconducting Linear Motor

To reduce the losses of the high-temperature superconducting (HTS) motor, thereby optimizing electromagnetic characteristics and reducing cooling costs, a design method of a low-loss partially HTS linear motor is proposed. Firstly, the thermal insulation configuration is designed to suppress mechanical conduction losses by the application of G-10 CR. Secondly, both the stator and mover are placed in a cryostat and isolated by a non-metallic protective cover which significantly reduces the air gap to reduce energy loss in the magnetic circuit, achieve a high magnetic flux density, and even suppress the eddy current loss. Finally, the temperature of the mover, the AC loss, radiation loss, mechanical conduction loss, and current lead conduction loss of HTS coils are calculated based on the thermal equivalent circuit model. And they are compared with solutions of the temperature and heat losses obtained through the finite element method (FEM). The differences of the temperature, conduction loss, and radiation loss of HTS coils calculated based on the thermal equivalent circuit and the FEM models are 1.7%, 4.7%, and 4.1% respectively, which proves the accuracy of the thermal equivalent circuit model and the heat losses quantification method. Based on the design method proposed, the total heat loss of the motor is 34 W at 46K, and only a single-stage cooler is required. The motor design method proposed can reduces heat losses, providing theoretical guidance for the further low-loss design of planar and rotary motors.