Losses in AC Superconducting Coils
AC superconducting wires are being developed so as to be applied to electrical machineries. The main concerns in developing the AC superconducting wires are AC losses. In order to assess AC losses in the form of winding, we made two AC superconducting coils having different rated capacities, 500kVA and 20kVA. The AC losses are measured by a calorimetric method.
Wire AC losses in the function of magnetic field strength and frequency are calculated from coil losses for each coil by a least square estimation method. In this process, we consideration for the magnetic field distribution in the coil windings were given.
The wire losses estimated from the measured coil losses were compared with the AC losses calculated by a set of usual theoretical formulations. In theory, AC loss components in proportion to magnetic field strength and frequency are regarded as hysteresis losses and components in proportion to the square of them are regarded as coupling losses. We divided the estimated AC losses into hysteresis loss components and coupling loss components.
The estimated hysteresis losses were about four times higher than the corresponding theoretical values and the coupling losses were 1.7 to 3 times higher than the corresponding theoretical values.
KeywordsMagnetic Field Strength Hysteresis Loss Magnetic Field Distribution Coupling Loss Copper Conductor
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