A two degree-of-freedom linear vibration energy harvester for tram applications

This article presents a new design method of a planar 3-degree-of-freedom serial manipulator-type electromagnetic vibration energy harvester in which any desired ratio of power peaks and three target resonant frequencies can be specified arbitrarily. The design of the harvester aims to achieve minimum difference between the power peaks generated at target frequencies. The geometrical positions of three normal modes are first determined and the corresponding stiffness matrix of the harvester is found. Second, the stiffness matrix can be synthesized by three serially connected torsional springs. Third, the leaf hinge joints corresponding to torsional springs are designed using the newly developed design equations. Finally, the array and the locations of the magnets are found using the sequential quadratic programming (SQP) algorithm. The experiments are conducted to verify the design method. Three resonant frequencies are measured at 23.4, 29.2, and 34.8 Hz comparing to the target frequencies of 25, 30, and 35 Hz. The peak powers of 1.28, 0.89, and 1.32 mW are obtained across the optimal load resistor of 1.01 kΩ under the condition of the constant acceleration of 1.5 m/s2.

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Theoretical modeling and analysis of a 2-degree-of-freedom hybrid piezoelectric–electromagnetic vibration energy harvester with a driven beam

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x18770870 ◽

2018 ◽

Vol 29 (11) ◽

pp. 2465-2476 ◽

Cited By ~ 8

Author(s):

Dan Zhao ◽

Shaogang Liu ◽

Qingtao Xu ◽

Wenyi Sun ◽

Tao Wang ◽

...

Keyword(s):

Energy Harvesting ◽

Output Power ◽

Energy Harvester ◽

Degree Of Freedom ◽

Energy Output ◽

Vibration Energy ◽

Vibration Energy Harvester ◽

Piezoelectric Energy ◽

Electromagnetic Vibration ◽

Operating Bandwidth

In the article, a novel 2-degree-of-freedom hybrid piecewise-linear piezoelectric–electromagnetic vibration energy harvester is presented to achieve better energy harvesting efficiency. The harvester consists of a primary piezoelectric energy harvesting device to which an electromagnetic mechanism is coupled to improve the integral energy output, and a driven beam is mounted to broaden the operating bandwidth by inducing nonlinearity. Considering the piezoelectric–electromagnetic coupling characteristics and the nonlinear factors, dynamic equations of the system are established. Expressions of the output power are deduced though averaging method. Characteristic parameters are analyzed theoretically, including the piezoelectric parameters, electromagnetic parameters, and the piecewise-linearity. Frequency sweep excitation test is conducted on the setup at an excitation acceleration of 0.3 g and results demonstrate that two resonant regions are obtained with the peak output power of 5.4 and 6.49 mW, respectively, and the operating bandwidth is increased by 8 Hz. Moreover, though adjusting the stiffness of the driven beam k3 and the gap between the primary beam and the driven beam d, the performance of the harvester can be further optimized.

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