Power density distribution analysis of an IPT system based on poynting vector

This paper proposes a Poynting vector based approach to quantitatively analyze power density distribution between two coupled coils of a near field IPT system. A geometry model is established with the primary coil is driven by a current source and the secondary is with a uniform distributed resistive load along it. The magnetic field, electric field, and power density represented by the Poynting vector at any arbitrary point between and around the coils are calculated respectively. Two unloaded and one loading conditions are studied, and it is found that the time averaged Poynting vectors are zero when the secondary coil is open or shorted circuited. When the secondary coil is uniformly loaded, the power density is determined by the system frequency, the radii of the primary and the secondary coil, the RMS values of coil currents, the phase difference between two coil currents, and the coupling distance. Numerical results show the power density distribution forms a donut shape in space concentrating along the edge the coils, instead of distributing coaxially along the center path.