Effect of misalignment on a Tripolar Pad WPT System and Recognition Methods

This Master's thesis work proposes an analytical study of the effects that misalignment causes in a wireless power transfer (WPT) system. WPT systems may become more practical charging solutions in the near future that will enable more frequent recharging, thus opening up the possibility of reducing the size of vehicle battery packs. Among the most important challenges to be faced, however, appear to be those of ensuring high transferable powers at efficiencies comparable to those of "wired" systems; in addition to the chosen geometry and electrical characteristics, misalignment is one of the factors that most degrades the performance of such systems: designing structures with high tolerance to misalignment and ensuring as much alignment as possible during energy transfer seem to be the two most important objectives in this regard. This thesis work proposes a simplified analytical model of a tripolar WPT system, through which a magnetic analysis is performed on the effects of misalignment between the two parts of the system. An algorithm based on Biot-Savart's law was used to calculate the magnetic couplings matrix for generic positions between the two pads; this matrix is then used in electrical simulations of the system, with the goal of analyzing the effects on the electrical quantities of the system due to the various possible misalignments. The main objective turns out to be to recognize the mutual position between the pads without using accessory systems, using only the electrical quantities easily measurable in the system.