Array of piezoelectric energy harvesting by the equivalent impedance approach

Abstract

This article proposes to use the idea of equivalent impedance to investigate the electrical response of an array of piezoelectric oscillators endowed with distinct energy harvesting circuits. Three interface electronics systems are considered including standard AC/DC and parallel/series-SSHI (synchronized switch harvesting on inductor) circuits. Various forms of equivalent load impedance are analytically obtained for different interfaces. The steady-state response of an array system is then shown to be determined by the matrix formulation of generalized Ohm’s law whose impedance matrix is explicitly expressed in terms of the load impedance. A model problem is proposed for evaluating the ability of power harvesting under various conditions. It is shown first that harvested power is increased dramatically for the case of small deviation in the system parameters. On the other hand, if the deviation in mass is relatively large, the result is changed from the power-boosting mode to wideband mode. In particular, the parallel-SSHI array system exhibits much more significant bandwidth improvement than the other two cases. Surprisingly, the series-SSHI array system shows the worst electrical response. Such an observation is opposed to our previous finding that an SSHI technique avails against the standard technique in the case based on a single piezoelectric energy harvester and the explanation is under investigation.

A multi-degree of freedom piezoelectric vibration energy harvester with piezoelectric elements inserted between two nearby oscillators

“…As a result, a number of approaches have been pursued to overcome this limitation. The approaches include multi-frequency Nomenclature u 0 the base excitation displacement u 1 the relative displacement of the 1st oscillator mass (m 1 ) with respect to the base u 2 the relative displacement of the 2nd oscillator mass (m 2 ) with respect to the base u n the relative displacement of the nth oscillator mass (m n ) with respect to the base m 1 the 1st oscillator mass m 2 the 2nd oscillator mass m n the nth oscillator mass k 1 the short circuit stiffness between the base and the oscillator (m 1 ) k 2 the short circuit stiffness between the m 1 and the m 2 k n the short circuit stiffness between the m n À 1 and the m n c 1 the short circuit mechanical damping between the base and the oscillator (m 1 ) c 2 the short circuit mechanical damping between the m 1 and the m 2 c n the short circuit mechanical damping between the m n À 1 and the m n C p1 the blocking capacity of the 1st piezoelectric patch element C p2 the blocking capacity of the 2nd piezoelectric patch element C pn the blocking capacity of the nth piezoelectric patch element R 1 the external resistance connected with 1st piezoelectric patch element R 2 the external resistance connected with 2nd piezoelectric patch element R n the external resistance connected with nth piezoelectric patch element α 1 the force factor of the 1st piezoelectric patch element α 2 the force factor of the 2nd piezoelectric patch element α n the force factor of the nth piezoelectric patch element V 1 the output voltage of the 1st piezoelectric patch element V 2 the output voltage of the 2nd piezoelectric patch element V n the output voltage of the nth piezoelectric patch element P 1 the harvested resonant power of the 1st piezoelectric patch element P 2 the harvested resonant power of the 2nd piezoelectric patch element P input the input power s the Laplace variable i the square root of À 1 η 1 the resonant energy harvesting efficiency of 1st piezoelectric patch element η 2 the resonant energy harvesting efficiency of 2nd piezoelectric patch element Superscripts U the first differential U U the second differential arrays [3][4][5], multi degrees of freedom energy harvester which is also known as multifunctional energy harvesting technology [6][7][8], passive and active self-resonant tuning technologies [9][10][11][12].…”

A friendly approach to increasing the frequency response of piezoelectric generators

“…A piezoelectric harvester is a high Q resonant device that can effectively pick up ambient vibration energy only at or near a particular resonant frequency. This is also evident from the expression of the output average power Pavg as function of vibration frequency [1], 2 3 res avg 2 2 2 res res m (f f ) P…”

“…Increasingly, efforts are being made to develop broadband energy harvesters that can harvest energy over a large frequency interval. Typically, this is achieved by electrically and/or mechanically connecting energy harvesters whose operating frequencies are slightly different from, but very close to each other [2]. However, these assembled generators must be carefully designed so that each individual generator does not effect the others.…”

A Novel Ropes-Driven Wideband Piezoelectric Vibration Energy Harvester

“…Firstly, it has the potential to achieve wider or even unlimited bandwidth by adding LFDBs connected with ropes. Secondly, the output power will not be weakened with the increasing number of LFDBs, unlike arrays of beams vibration energy harvester (AB-VEH) for wider bandwidth [19][20][21][22][23], and the reason in shown below. …”

“…In the case of the multimodal harvesting technique, it is mainly based on the structure of beam arrays, which have different frequencies to match the wideband excitation's components, can be classified into unconnected mechanical structure systems [19][20][21][22][23]-connected mechanical structure systems using springs [24,25]-and multi-resonance systems [26][27][28][29][30][31]. Compared with a conventional single piezoelectric beam EH, much higher bandwidth of the EH can be realized by the multimodal harvesting technique.…”