An Accurate Model of Magnetic Energy Harvester in the Saturated Region for Harvesting Maximum Power: Analysis, Design, and Experimental Verification

Abstract

To reduce the size and weight of the magnetic energy harvester (MEH), the magnetic core should be designed to work in the maximum power region, i.e., in the saturated region. However, the conventional analysis model of the MEH, which ignores the phase difference between the primary and secondary currents, is only suitable for the unsaturated region. When the core is in the saturated region, the results of the numerical calculation severely deviate from the experimental observations due to the non-negligible phase difference. To address this vital problem, this article establishes an excitation current model (ECM) to calculate the phase difference caused by the magnetizing inductance. An accurate model of the MEH is presented based on the ECM in this article, which can calculate the harvesting power of the MEH in the saturated region. Besides, a strategy for finding the maximum power point is proposed, which can be used for the designing of the MEH. Finally, an experimental prototype is constructed to verify the effectiveness of the proposed analysis model and the design method of the MEH. The experimental results show that the proposed analysis model can maintain high accuracy when the magnetic core enters the saturated region, and the MEH designed by the proposed model can reach the expected power with a compact size. Compared with the theoretical value, the output voltage deviation of the MEH is only 0.4%, and the output power deviation is only 0.8%.