Inductive magnetic energy harvesting

Abstract

This thesis first reviews the challenges and limitations of the existing approaches designed for inductive magnetic energy harvesting systems. An equivalent circuit model of magnetic energy harvester is developed, which takes into account the nonlinearity of the magnetic reluctance and flux. Then, using the models, a family of low threshold capacitive rectifier topologies and a center tapped boost-derived AC-DC converter are derived for better convert the AC harvesting power to DC voltage. Both of the approaches avoid using the conventional two stage structure and increases the efficiency and system output power. Two new impedance matching control algorithms for bridgeless AC-DC power conversion of magnetic harvester are presented: a Phase/RMS maximum power point tracking (MPPT) method, which controls the phase and RMS value of the converter input current without voltage reference, and a Quasi-MPPT method simplified from Phase/RMS MPPT. Experimental results are presented to validated the proposed modeling, power conversion and control approaches. Comparison with previous work shows that the proposed approaches achieve higher output power for the magnetic energy harvesting system.