Superconducting motor refers to the motor whose winding is made of practical superconducting wire

Characteristic：

 Superconductivity has zero resistance at critical temperature T, critical magnetic field strength H and critical current density J .T This will reduce the resistance loss of superconducting motor winding to zero, not only solve the problem of armature winding heating and temperature rise, but also greatly improve the efficiency of the motor. What's more, the critical magnetic field strength and critical current density of the superconductor are very high, which makes the air gap flux density and the current density of the winding of the superconductor motor several times or even tens of times higher than that of the conventional motor. This greatly improves the power density of the motor and reduces the weight, volume and material consumption of the motor. Since 1986, the discovery of superconducting materials with high critical temperature (liquid nitrogen temperature region) has shown a new prospect for the practical application of superconducting motors. Superconducting motor is mainly made of turbo generator and single pole DC motor.

Classification:

Superconducting Turbogenerator

The excitation winding is wound with a super conductor (NB-Ti alloy wire or Nb3Sn). The selected current density is dozens of times higher than that of conventional winding. The flux air gap density of the motor is very high, which is much higher than the saturation point of the ferromagnetic material (silicon steel sheet, etc.). Therefore, the weight of the generator is greatly reduced, the maximum value of the electromagnetic power of the generator is increased, and the motor can cope with greater power mutation, which is conducive to the stability of the grid connected operation of the motor. At present, because the AC superconducting materials with strong magnetic field and high current density haven't passed the standard, the super conductor can only be used in the DC excitation winding, while the conventional conductor (copper wire) is still used in the AC armature winding. The superconducting excitation winding of the rotor is immersed in a rotating cryogenic liquid helium container, and liquid helium is transported from the inner layer of the multi-layer shaft to cool the excitation winding. The evaporated gaseous helium flows out of the interlayer of the multi-layer rotating shaft. In order to avoid the invasion of external heat, the shell of the rotating cryogenic vessel and the interlayer of the multi-layer rotating shaft are provided with vacuum insulation interlayer. The whole set of low temperature system is strictly sealed. The outer layer of the rotor is also equipped with a resistance Ni screen made of metal materials to shield the stator harmonic magnetic field and the negative sequence magnetic field of the generator in three-phase asymmetric operation from entering the superconducting excitation winding, so as to avoid the loss of superconductivity of the superconducting materials.

Superconducting single pole DC motor

The DC motor with high voltage, high current and large capacity can be made by using superconducting excitation winding and liquid brush. There are two types: disc type and fold in type. Both motors can be used for generator operation (driven by prime mover) or for motor operation (current introduced by brush). Superconducting single pole DC motor is suitable for ship propulsion, steel rolling, large-scale winch and slow speed compressor, and has a bright future.