Abstract: This paper presents a two-degree-of-freedom (2DOF) hybrid piezoelectric-electromagnetic energy harvester (P-EMEH). Such a 2DOF system is designed to achieve two close resonant frequencies. The combined piezoelectric-electromagnetic conversion mechanism is exploited to further improve the total power output of the system in comparison to a stand-alone piezoelectric or electromagnetic conversion mechanism. First, a mathematical model for the 2DOF hybrid P-EMEH is established. Subsequently, the maximal power output of the 2DOF hybrid P-EMEH is compared both experimentally and theoretically with those from the 1DOF piezoelectric energy harvester (PEH), 1DOF electromagnetic energy harvester (EMEH), 2DOF PEH, and 2DOF EMEH. Based on the validated mathematical model, the effect of the effective electromechanical coupling coefficients (EMCC) on the maximal power outputs from various harvester configurations is analyzed. The results indicate that for the 2DOF hybrid P-EMEH, although the increase of the power output from one electromechanical transducer will lead to the decrease of the power output from the other, the overall performance of the system is improved in weak and medium coupling regimes by increasing electromechanical coupling. In weak and medium coupling scenarios, the hybrid energy harvester configuration is advantageous over conventional 1DOF or 2DOF harvester configurations with a stand-alone conversion mechanism.

一种两自由度的压电-电磁复合能量收集器

研究目的：对一种两自由度的压电-电磁复合能量收集器进行发电性能研究。
创新要点：建立了一种两自由度压电-电磁复合能量收集器发电性能的数学模型，该数学模型可以评估两自由度压电-电磁复合能量收集器中压电元件、电磁元件以及系统总输出功率。
研究方法：对一种两自由度的压电-电磁复合能量收集器进行数学建模，并实验验证数学模型的正确性。基于实验测试得到的系统参数值，理论研究压电元件和电磁元件的机电耦合系数对不同能量收集器发电性能的影响关系，并对几种能量收集器的发电能力进行对比分析。
重要结论：对于非强耦合（弱或中间耦合）的两自由度机电转换器，复合能量收集器（压电+电磁）具有比单一能量收集器（压电或电磁）更高的发电能力。
振动；复合能量收集；两自由度模型；压电；电磁

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