Power Supply Based on Inductive Harvesting From Structural Currents

Abstract

Monitoring infrastructure offers functional optimization, lower maintenance cost, security, stability, and data analysis benefits. Sensor nodes require some level of energy autonomy for reliable and cost-effective operation, and energy-harvesting methods have been developed in the last two decades for this purpose. Here, a power supply that collects, stores, and delivers regulated power from the stray magnetic field of current-carrying structures is presented. In cm-scale structures the skin effect concentrates current at edges at frequencies even below 1 kHz. A coil-core inductive transducer is designed. A flux-funneling soft magnetic core shape is used, multiplying power density by the square of funneling ratio. A power management circuit combining reactance cancelation, voltage doubling, rectification, supercapacitor storage, and switched inductor voltage boosting and regulation is introduced. The power supply is characterized in house and on a full-size industrial setup, demonstrating a power reception density of 0.36, 0.54, and 0.73 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> from a 25-A root-mean-square structural current at 360, 500, and 800 Hz, respectively, corresponding to the frequency range of aircraft currents. The regulated output is tested under various loads and cold starting is demonstrated. The introduced method may enable power autonomy to wireless sensors deployed in current-carrying infrastructure.