Largely enhancing the output power and charging efficiency of electret generators using position-based auto-switch and passive power management module

Impedance mismatch and low charging efficiency are serious obstacles for electrostatic generators directly powering commercial electronics. Here, a rotary freestanding-electret generator (FEG) with a position-based auto-switch (swFEG) is developed, which expands the range of the adaptable load resistance and largely improves the maximum average output power up to 3.77 times that of the conventional FEG in theory. Based on the swFEG, a passive power management module (PMM), including a diode rectifier, an inductor, and a storage capacitor, is designed. And the charging power of swFEG with PMM can reach 3.62 times the maximum average output power of the FEG in simulation. In experiment, the maximum average output power of the swFEG achieved 1.5 times that of the FEG, and the swFEG with PMM can charge a capacitor with 68% efficiency. The reason why the experimental outputs lower than the theoretical ones was analyzed. Nevertheless, the swFEG dramatically improves the output power and the swFEG with PMM provides a high charging efficiency strategy.