Parameter-Optimization-Based Maximum Power Reaching for Magnetic Field Energy Harvesters Connected to Buck Converter

Magnetic field energy harvesters (MFEHs) have emerged as a promising power supply method for online monitoring devices. However, under low current conditions, the magnetic field weakens, presenting challenges such as unstable supply voltage and insufficient power. To improve the adaptability of the MFEH to low currents and enable it to operate stably under such conditions, it is essential for the MFEH to operate near the maximum power point (MPP). To address this vital problem, an MPP reaching method based on parameter optimization is proposed in this work, which can be used to improve the performance of the MFEH. Specifically, the operating characteristics of the MFEH and the startup process of the Buck converter are analyzed. Subsequently, a parameter optimization method is developed, which ensures the simultaneous achievement of constant voltage (CV) output and MPP reaching. An experimental prototype is constructed to verify the effectiveness of the proposal. Experimental results demonstrate that the startup process of the Buck converter is consistent with the theoretical analysis. Furthermore, by adopting the parameter optimization method, the output power is improved at different currents, thereby reducing the current required at the rated power. Under a power requirement of 1 W, compared toN= 70 andN= 210, the required current in the case ofN= 140 decreases from 36.3 A and 22.0 A to 20.8 A, representing reductions of 42.7% and 5.5%, respectively. For a power requirement of 3.5 W, the required current decreases from 88.3 A and 66.0 A to 57.0 A, with reductions of 35.4% and 13.6%, respectively.