Optimization of wireless charging systems with series LC-topology and multi-layer coil design

One of the key problems in the construction of wireless charging systems is to increase the efficiency of wireless energy transfer, especially with limited dimensions of devices and changing mutual position of coils. Traditional design methods are often insufficiently accurate for multilayer coils, which requires the development of new approaches. The study is based on a mathematical model of a wireless energy transfer system with a series LC topology, built on the basis of equivalent circuits, while the parameters of the transmitting and receiving coils are determined using the vector potential method. An approach is proposed that allows reducing the number of variable parameters that determine the efficiency of wireless energy transfer. A technique for optimizing the considered wireless charging systems at the design stage is developed, according to the criteria of wireless energy transfer efficiency, the value of the transmitted power and over-voltage on the capacitors of the resonant circuit. The technique is based on multi-criteria analysis using relative im-portance coefficients. For specific conditions, the optimal parameters of the transmitting and receiving coils are determined, namely the number of turns and layers of the winding under given dimensional constraints, ensuring maximum efficiency. Experimental testing on a model confirmed the correspondence of the calculated and real characteristics with sufficient reliability. It is shown that the proposed approach allows one to effectively take into account geometric constraints and minimize losses in the resonant circuit. The proposed optimization method demonstrates high efficiency in the design of wireless charging systems with multilayer coils and series LC topology under conditions of possible coil displacements.