Inductive Energy Harvesting System for Power Cables with Forced Linear Operation

Abstract:
Permanent condition monitoring of power cables requires a high number of active sensors that need a constant voltage and power supply. An effective and intelligent way of energy supply is harvesting the required energy based on the magnetic field energy of the power cable. To couple this magnetic field, a ferromagnetic toroidal core is usually installed around the power cable. On the core a secondary winding is wound. Because of the power cable’s alternating current, a voltage is induced across this winding, which can be used to supply energy to small consumers. Due to saturation effects of the magnetic material and the highly varying amplitude of the power cable current, the development and dimensioning of an inductive energy harvesting system is a complex task. For this purpose, this paper presents an approach that enforces a linear operating point in the energy harvesting system, thus avoiding the unwanted saturation effects over a wide input current range. A model of the energy harvesting device is established and validated, which can be used to gain knowledge about the available power and whether the developed system is able to supply a sensor with sufficient energy.