HTS Wind Power Generator: Electromagnetic Force Between No-Insulation and Insulation Coils Under Time-Varying Conditions

This paper presents experimental and analytical results of electromagnetic forces between no-insulation (NI) and insulation (INS) coils under time-varying conditions for NI coils that may be used in wind power generator. Three test pancake coils, one NI and the others INS, of the identical winding i.d., bore size, and number of turns, are wound with GdBCO coated tape. To determine an electric circuit model of the NI coil, the coil was charged-and-discharged at different ramping rates. The data were used to compute a characteristic resistance of a parallel inductor/resistor circuit model. In force measurement, two sets of pancake pairs were tested, NI-INS and INS-INS, the later for comparison. The coils were tested in a bath of liquid nitrogen at 77 K. The dynamic force response of the NI-INS pair was compared with that of INS-INS. The analysis based on the circuit model was tested with the experimental results. Analysis agrees well with experiment, validating our technique to analyze the time-varying forces between the NI-INS pair.