Harvesting ambient mechanical energy is a crucial method to gain low-cost, clean and sustainable electric energy for self-powered electronics. Herein, we develop a freestanding-electret rotary generator and the explicit analytical solutions of the output current, voltage and average power are obtained from its theoretical model. The maximum average output power and the matched load resistance can be estimated directly from simple formulas. The generator using an inexpensive micro-nano-structured PTFE electret film achieves an open-circuit voltage with an amplitude of 650 V and a conversion efficiency about 56% with 10.5 mW output power at a rotation rate of 750 rpm. We find that the opposite charges injected into the back of the electret during the charging process tremendously counteract the effect of the charges on the front and reduce the output power. Eventually the theoretical and experimental results are very close when the net charge density is used instead of the surface charge density.

收集环境机械能是为自供电电子设备获取低成本，清洁和可持续电能的关键方法。本文中，我们开发了一种独立式驻极体旋转发电机，并从其理论模型获得了输出电流，电压和平均功率的明确解析解。最大平均输出功率和匹配的负载电阻可以直接通过简单公式估算。使用便宜的微纳米结构PTFE驻极体薄膜的发电机，在750 rpm的转速下，以10.5 mW的输出功率实现了650 V的开路电压和约56％的转换效率。我们发现，在充电过程中注入驻极体背面的相反电荷极大地抵消了正面电荷的影响，并降低了输出功率。最终，当使用净电荷密度代替表面电荷密度时，理论和实验结果非常接近。