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

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