A Synchronous Current Inversion and Energy Extraction Circuit for Electromagnetic Energy Harvesting

Synchronous switch (SS) technique has been extensively studied in piezoelectric energy harvesting (PEH). The SS circuits can significantly enhance the output power under the same vibration excitation. Some SS solutions have also been developed for an inductive electromagnetic (EM) source by referring to its capacitive PEH counterpart and taking a complementary design. This paper proposes a synchronized current inversion and energy extraction (SCIEE) circuit for EM energy harvesting (EMEH). SCIEE utilizes two switched capacitive branches to carry out the synchronized current inversion at the electromotive voltage negative-to-positive zero-crossing instants and energy extraction at the voltage positive-to-negative zero-crossing instants. Theoretical analysis shows that the proposed circuit is suitable to be used with an EM transducer, whose quality factor is relatively large. Experiments show that, under the same mechanical excitation, SCIEE can harvest 25% more power compared with the cutting-edge synchronized switch energy extraction (SSEE) circuit for EMEH.