What Is a Superconducting Motor?
Superconducting motors utilize the phenomenon of superconductivity, where electrical resistance drops to zero at very low temperatures. This allows for the flow of large currents at low voltage, creating strong magnetic fields and enabling motors with excellent torque characteristics.
However, exceeding a critical magnetic field can disrupt the superconducting state of the superconducting wire, reverting it to normal conductivity with standard electrical resistance. Thus, careful management of superconducting magnetic fields is crucial.
Uses of Superconducting Motors
Superconducting motors are expected to be smaller and lighter than traditional electric motors with equivalent output. They are anticipated for use in applications like superconducting linear railroads (linear motor cars), propulsion engines for ships and aircraft, and more.
Examples of practical applications include the Shanghai Maglev Train and Japan’s JR Tokai superconducting linear motor car, slated to open in 2027. Additionally, superconductivity is already employed in medical MRI equipment.
Principle of Superconducting Motors
Superconducting motors use coils made of superconducting wires in the motor rotor, achieving low-loss, high-efficiency operation with excellent torque. Magnets leveraging superconductivity create powerful magnetic fields for linear motor cars, reducing resistance components like wheel friction and enabling ultra-high-speed operation.
Niobium-titanium alloy (Nb-Ti) magnets exhibit superconductivity at the low temperature of 4K (-516°F) in liquid helium. Recent advancements include bismuth-based copper oxide, a high-temperature superconducting magnet that achieves superconductivity at 77K (-516°F) with liquid nitrogen, offering lower costs and easier handling than liquid helium.
Despite ongoing research and development, there are still challenges to overcome before widespread practical application, with major companies in the heavy industry sector actively involved in this work.