earticle

영어

Recently, as the sense of crisis over global climate change has grown, the international community is implementing carbon emission regulations and carbon neutrality policies. Efforts to reduce emissions are being strengthened in the transportation and transport sectors, which account for 25% of global greenhouse gas emissions. In response to these regulations and policies, efforts are being made to apply eco-friendly electric propulsion technology to aircraft, ships, and automobiles. Researches are being conducted to improve power density and efficiency by using superconductors that have a high current density compared to the copper wire and whose electrical resistance becomes “0” below the critical condition. Among the electromagnet technologies utilizing the high-temperature superconductors (HTS), the non-insulated (NI) winding technique that removes insulation between winding turns can dramatically improve thermal, electrical, and mechanical stability compared to the existing insulation method. However, technical problems arise due to current leakage, such as magnetic field charging-delay and -loss. Especially, when applying the NI technique to the field coil of a HTS synchronous motor, the output responsiveness may be degraded due to current leakage when the motor speed or load changes. Therefore, in this paper, the dynamic characteristics of a HTS motor were analyzed by changing the contact resistance of the NI field coil, which determine the current leakage. By modeling the d−q equivalent circuit for a HTS motor, the motor speed, torque, field leakage current, and field voltage according to the change in d-axis current were analyzed when controlling the maximum torque operation per unit current.