低频螺旋状压电俘能器结构性能分析

利用螺旋状双晶片压电梁式俘能器可以有效地从低频工作环境中提取能量.由于这种俘能结构振动中存在弯曲振动和伸缩振动两种模态,确定俘能器的最优工作模态非常重要,这样外载作用型式(即面内受载还是面外受载)对俘能器的影响较大.数值结果表明:外激励方向不同时,最大输出功率密度出现在不同阶数的固有频率处,并且最大输出功率密度的大小也显著不同,面内加载方式明显优于面外加载方式.最后还详细讨论了储能电路的阻抗,自由端悬挂的集中质量对俘能器性能的影响规律.

ANALYSIS ON STRUCTURE AND PERFORMANCE OF A LOW FREQUENCY PIEZOELECTRIC POWER HARVESTER USING A SPIRAL-SHAPED BIMORPH

The mechanical energy existing in the ambient environment with lower frequency can be effectively extracted by using spiral-shaped piezoelectric bimorph power harvesters.Since there exist two kinds of vibration modes,flexural and extensional,in a spiral-shaped piezoelectric bimorph,it is very important to make clear which mode is optimal as the operating mode.External excitation(i.e.in-plane forcing or out-of-plane forcing or combination of both) has stronger effect on the harvester performance.The numerical results show that different external forcing induces different order vibration mode with an optimal output power density.Comparing these optimal power densities,we find that the in-plane forcing is much more favorable than the two others.Finally,the effect of the impedance,standing for a storage circuit,and the concentrated mass at the free end of the bimorph on the harvester performance is discussed in detail.