The quasi-static near electric field of an inductive power transfer system

The q uasi-static near magnetic field of an inductive power transfer system would be expected to be intense. However, the quasi-static near electric field is also quite intense and merits investigation. As for any vector field, the near electric field can be decomposed into conservative and solenoidal components. The solenoidal component is the one that would be anticipated from Faraday´s law. However, as in the electric field produced by many MRI gradient coils, the conservative component is the dominant component of the electric field. The conservative electric field can be thought of as arising from the voltage drop across the windings. When the magnetic cores of the windings are fabricated from more than one piece of ferrite, very intense electric field can exist in the air gaps in the composite structures. The electric field in the air gaps can exceed the breakdown field for air and thus arcing must be prevented with high strength dielectric material. The extraneous electric field of an inductive power transfer system can be minimized through electrostatic shielding, but only partly due to the effect such shielding can have on the efficiency of the system.