基于人体运动的压电-电磁混合式振动能量采集研究

将人体运动产生的动能转化为可利用的电能为传感器供电一直是能量采研究中的一个热点。如何有效利用人体运动，增强环境适应能力以及提高能量采集性能仍是俘能研究中需要解决的关键问题。本文基于人体运动特性，设计了一种新型的混合式能量采集器，同时具有压电和电磁转化机制。压电俘能是基于压电梁变形产生电能，电磁发电机采用堆叠磁组构型来切割线圈产生电动势。首先建立了混合式能量采集器的动力学理论模型，用来描述输出电压特性，并与实验进行了对比验证。理论与实验研究均表明，混合式俘能器的输出电压在一定激励频率范围内出现两个波峰。通过调节压电梁长度，可以改变峰值大小以及两个峰值间的频段范围。人体运动实验表明，混合式俘能器中可以在短时间内提供较高的电压输出，比如当跑步速度为5km/h时，3s内就可以输出1.1V直流电压驱动传感器工作；跑步时长为30s时，传感器正常工作时常可以达到77s。本文设计的混合式俘能器不仅可以快速供电，还具有较强的续航能力，这为电池充电或传感器供电提供了潜在的应用价值。

A new hybrid energy harvester for human motion power generation

Converting energy from human motions into usable electricity for powering the operation of sensors is always a hot topic in energy harvesting researches. Yet how to efficiently exploit human motion and improve the level of output power are still key problems to be solved as well as the environmental adaptability. Based on the feature of human walking or running, a new hybrid energy harvester is proposed and designed, with consideration of combining piezoelectric and electromagnetic mechanisms. The piezoelectric energy harvesting is based on the strain of a piezoelectric beam, while the electromagnetic generator employs the configuration of stacked magnetic group cutting the coil. The theoretical model for the hybrid energy harvesting system is constructed to describe the characteristics of output voltage on the base of lumped parameter model. The predicted results are compared with the experimental measurements. The comparison agrees well which indicates the feasibility of the present model. It is found that there are two peaks of output voltage within the excitation frequency region. The results show that these two peaks can be adjusted by varying the length of piezoelectric beam which is related with the nature frequency of energy harvester. In this way, the bandwidth of energy harvesting can be increased when the two peaks are closing to each other according to the excitation frequency in surroundings. In addition, human motion experiments display that the hybrid energy harvester can output high DC voltage in a short time, for instance, when the running speed is 5km/h, 1.1V DV voltage is produced in 3 seconds to drive the sensor to work. When the time length of running is 30 seconds, the sensor can work for 77 seconds by virtue of the hybrid energy harvester. The present hybrid energy harvester has abilities of quick charge and endurance which offers potential applications of charging battery or powering sensors.