A new role of SFRA for reliable performance in wireless power transfer system

Abstract

Since sweep frequency response analyzer( SFRA) was introduced in the power industry last few decades, the reliability of high voltage (HV) winding apparatus (i.e., power transformers and rotating machines) could be objectively examined by analysing the transformation of electrical components. The principle of inductively-coupled wireless power transfer (WPT) system is based on Faraday’s low and Tesla’s idea of alternative current alike a traditional power transformer. As the demand for wireless battery charging devices increases significantly, and the power rate of the current WPT device reaches Mega Watt ranges, the cost-effective condition monitoring method for a reliable WPT system is necessary. Hence, SFRA can conduct vital roles in WPT devices. First, SFRA provides accurate readings of electrical parameters: winding resistance (R), self and mutual inductance (L) and compensating capacitance (C) with respect to frequency in the design phase. Second, single or multiple resonant points over the transfer distance are observed precisely. Third, the different values of RL Ccomponents are detected due to the deterioration, misalignment of windings and characteristic variation of magnetic supplement over time since the WPT is installed on-site. This study introduces circuit analysis of the two-coil WPT system and the design process with simulation and SFRA. Furthermore, three critical roles of SFRA mentioned above are investigated in practical demonstration.