A Low-Power MPPT Electromagnetic Energy Harvesting Circuit Based on Wave Frequency Detection

This article presents a low-power maximum power point tracking (MPPT) interface circuit designed for various electromagnetic wave energy harvesters. The premise of traditional MPPT techniques that involve impedance matching with the electromagnetic generator (EMG) internal resistance is that the EMG must be capable of outputting sufficient power. However, due to the constraints imposed by the mass and size of wave energy harvesters, the power they can capture from wave vibrations is limited. The proposed MPPT circuit aims to optimize the utilization of environmental vibrational energy. This method utilizes mercury switches to detect the frequency of wave vibrations and adjusts the equivalent load impedance through pulse-width modulation (PWM) to achieve optimal electromagnetic damping. This enables the EMG speed to synchronize with the wave frequency, maintaining resonance in the energy harvester and facilitating MPPT. The proposed circuit has been analyzed using both theoretical and simulation methods. Experimental results indicate that, within a frequency range of 0.4–1.0 Hz and an amplitude of ±20°, the designed MPPT circuit allows the energy harvester to function in a resonant state. The controller's tracking error is less than 1%, and it has a power consumption of approximately 0.53 mW.