Power loss analysis with high primary current in magnetic energy harvesters

This paper presents an analysis of a magnetic energy harvester operating from a high power primary device with substantial current consumption. The existing ‘transfer window alignment (TWA)’ technique that can significantly boost the amount of harvested power from magnetic fields is revisited with a high primary current scenario, revealing that any shifting of the transfer window from passive rectification can be suboptimal once the primary side current goes beyond a certain level. This is caused by undesirable development of flux due to parasitic elements in the circuits. A new model to predict such an issue is first derived, and its simulation results are provided. The estimation of the critical level in the primary side current is explored, and the optimal strategy of a magnetic energy harvester that operates with a wide range of primary current is discussed.