Overview of different alternatives for the contact-less transmission of energy

When a physical connection cannot exist between the power source and the load, a transformer is usually used as a power link to transfer the energy. Primary and secondary windings of this transformer are usually separated a distance that is quite large compared to its own size. This means that coupling is low and leakage inductance is higher or comparable to the magnetising inductance. Therefore, voltage gain is low and a considerable part of the primary current will flow through the magnetising inductance and go back to the power source. An important effort has been done in the last years, proposing different topologies suitable for contact-less applications and suggesting design rules in order to improve coupling of the contact-less transformer. This paper presents an overview of many of the proposals, comparing the converters results in terms of efficiency, size, coupling of the transformer and control method.