Highly Efficient Power-Line Energy Harvesting with Adaptive Matching Capacitance for Residential Self-Powered Sensing

Sensor nodes for smart homes require sufficient energy to perform sensing, signal processing, and communication tasks. Magnetic field energy harvesting (MEH) from power lines emerges as a promising approach. In this study, we propose a novel method for harvesting magnetic power-line energy taking advantages of LC resonance. The system consists of magnetic coils and adjustable matching capacitance to create resonant units. With consideration of the nonlinearity of the MEH system, we illustrate how the system dynamics would shift under different currents in the power line. In response to these variations, a dynamic control strategy for adjusting the matching capacitance is proposed. Experimental studies reveal that the proposed MEH system achieves a maximum average output power of 0.31 mW at an optimal resistive load of 9 kΩ under 0.04 A_rms current at 50 Hz (3.88 mW/cm³/A_rms). In addition, a fully functional wireless sensor node can be powered. The proposed strategy enhances both output power and adaptive capability of the MEH system, ensuring reliable performance in self-powered wireless monitoring of power cable conditions for residential and industrial buildings.