Performance Assessment of Clamped-On Passive Magnetic Energy Harvester Matched to a Constant Voltage Load Under Wide Range of Primary Currents

Abstract

This article concerns passive magnetic energy harvesters (PMEHs) employed to supply low-voltage (typically dc) loads from high-ac-current-carrying conductors (e.g., a drone battery charging platform residing on a split phase of an overhead power line). It has recently been shown that a unique load voltage value maximizes harvested device power, regardless of primary current magnitude, assuming a sufficiently low magnetizing current in the PMEH transformer core. Corresponding simplified design guidelines were derived, allowing optimal matching of a PMEH to a constant-voltage-type load (CVL) by properly selecting the transformer core cross-sectional area and the number of secondary winding turns. However, disregarding core magnetizing current may not be accurate in practice even under high primary currents due to the utilization of a gapped core, required for the PMEH to clamp on/off an existing power line. This article aims to assess the actual performance of a clamped-on PMEH designed to drive a certain CVL using aforementioned simplified guidelines under a wide range of primary current magnitudes. It is revealed that the loci of harvested PMEH power deviates noticeably from the corresponding maximum power line (MPL). However, the harvested power difference is negligible due to the low sensitivity of power–voltage PMEH characteristics in the vicinity of the MPL. The presented findings are accurately supported by experimental results of a PMEH sized (using simplified design guidelines) to harvest 220 W from a conductor carrying 300 ARMS current while supplying a 45-V CVL.