Poynting Vector Flow Analysis for Contactless Energy Transfer in Magnetic Systems

Most problems related to contactless energy transfer are usually dealt within the framework of transformer theory, employing equivalent electric circuits as a tool for their analysis. Here, however, a physics approach based on the Maxwell equations is followed. Electric and magnetic fields are utilized to evaluate the Poynting vector, which defines the direction and power density carried by the electromagnetic field. The concepts of magnetic voltage and magnetic flux are utilized to define the instantaneous power guided within the magnetic transmitter. Contactless energy transfer requires two separate parts, a transmitter and a receiver circuit. In this paper, we pay attention to the electromagnetic field guided and emitted by the transmitter; internal skin effect (eddy currents losses) is accounted for; electromagnetic energy leaving the transmitter is evaluated using short-dipole antenna theory. This paper does not offer a new practical application of contactless energy transfer. Its scope is rather different; its aim is to provide a fresh look on contactless energy transfer in the context of an electromagnetics framework.