Optimal Load Type for Passive Magnetic Energy Harvesters

Due to the practical current source characteristics of a passive magnetic energy harvester, it may be conveniently interfaced by either voltage-type or resistance-type load. The load type preferable for interfacing an energy source is the one possessing the narrowest range of values belonging to the maximum power line (a curve linking all possible maximum power point coordinates of power source output characteristics). The brief adopts a set of recently developed equations to compare output characteristics (power-voltage and power-resistance) of a passive magnetic energy harvester and corresponding maximum power lines under a wide range of primary currents. It is clearly shown that voltage-type load should be preferred over resistance-type load for passive magnetic energy harvester interfacing. The findings are supported by experimental results of a passive magnetic energy harvester operating under primary currents of 50-350 A.