Magnetic frequency modulation mechanism of a non-contact magnetism-toggled rotary energy harvester coupling piezoelectric effect

Harvesting Energy from the ambient environment is a promising technology for promoting the development of the wireless sensor network or portable electronic devices. In this work, a non-contact magnetism-toggled rotary energy harvester is proposed. A mathematic model of the harvester is established, and its rationality and applicability were verified through experimental testing. This study mainly explores the magnetic frequency modulation mechanism. The results show a relationship between the number of magnets, natural frequency, and rotation speed; the fewer the number of excitation magnets, the more effective operating rotation speeds (wider frequency band), but the smaller the output power. In the experiment testing, the harvester had the output power of 4.51 mW obtained by the RMS value of the voltage at 251 rpm and 0.2 MΩ. It could directly light up 23 series connected LEDs and drive multi-sensor integrated devices, which has manifested the potential to supply energy for low-power electronic devices.