Comparison of Methods for Thermal Parameters Measurements of an Air Transformer

The paper presents two methods of measuring thermal parameters of an air transformer that is used in Wireless Power Transfer (WPT) systems. These are electrical and optical methods. The way of implementation of these methods is described and the measurement error of the considered methods is estimated. These methods are used to determine self thermal resistances of each winding and transfer thermal resistance between the windings of the investigated air transformer. These parameters characterize self-heating phenomena in each of the windings and mutual thermal couplings between these windings. The measurement results obtained using both the measurement methods are compared and the obtained discrepancies between these results are discussed. The influence of the current of the windings and the distance between them on the measured thermal resistances is also discussed.