With the increasing demand for power supply in power Internet-of-Things (IoT) sensor nodes, providing stable, self-powered operation near power-frequency transformers remains a critical challenge. This paper presents the design of an energy harvester based on FeCoV–PZT laminated magnetoelectric composites for efficiently harvesting 50 Hz stray magnetic field energy around power transformers. This study leverages the Ericsson cycle theory as a guiding principle for the critical selection of the magnetostrictive phase, ultimately identifying FeCoV for its optimal energy conversion potential. By employing a cantilever structure integrated with an NdFeB permanent magnet at the free end, the resonant frequency of the device is significantly reduced and matched to the power frequency, thereby enhancing the magnetoelectric conversion efficiency without requiring a bias magnetic field. Experimental results demonstrate that, through structural optimization, the resonant frequency can be reduced to ≈50 Hz, substantially improving conversion efficiency; a peak magnetoelectric coefficient of 3.8 V/(cm Oe) and a maximum output volume power density of 7.6 μW/cm3 were achieved, showing its potential for practical applications.
Zhang et al. (Sun,) studied this question.