Contactless Energy Transfer - Analytical Calculation of the Coil Systems’ Efficiencies for Different Topologies

In this paper, the losses of the coil system for different system topologies are analytically calculated. The different system topologies comprise on the one hand serial compensated coils and on the other hand parallel compensated coils. Each of the four possible combinations with one capacitor on each side has a different solution for the efficiency depending on the load resistance, the quality factor, the magnetic coupling, the design frequency and the secondary side inductance. The calculation considers only the fundamental frequency, thus harmonics as well as losses in inverter and rectifier are neglected. The paper concludes with a comparison of the different topologies based on a varying load resistance and points out the operating point with maximum efficiency.