The Power and Efficiency Limits of Piezoelectric Energy Harvesting

Abstract

The fundamental limits of cantilevered piezoelectric energy harvesters have not been well established. As with any other power generation technology, it is critical to establish the limits of power output and efficiency. Mathematical models for piezoelectric energy harvester power output have seen continued refinement, but these models have mainly been used and compared to individual harvester designs. Moreover, existing models all assume power scales with acceleration input, and take no account for the upper limit of the acceleration due to the ultimate strength of the piezoelectric material. Additionally, models for efficiency have been developed, but the limits have not been thoroughly explored. In this paper, we present the upper limits of input acceleration and output power for a piezoelectric harvester device. We then use these expressions, along with a previously developed ideal design method, to explore the upper limits of power production across a range of system masses and excitation frequencies. We also investigate general efficiency limits of these devices. We show the upper limit using an existing model and develop an alternate model that is applicable to excitation sources that are not capable of energy recovery.

Piezoelectric Ceramics for Use in Multilayer Actuators and Energy Harvesters

“…Field-induced strain (S-E) curves were measured using a laser displacement sensor (LK-G10, Keyence Co. Tokyo, Japan) with a resolution of 10 nm and a spot size of 20 lm. Figure 1 shows the XRD patterns of the PZ 1Àx T x -PZNN (0.50 ≤ x ≤ 0.55) ceramics sintered at 1150°C for 2 h. The inset shows the (111) peak of the specimen with x = 0.52 obtained by slow scanning; the (111) peak consisted of two peaks, (111) and (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11), indicating that this specimen had a rhombohedral structure. Therefore, it was concluded that the specimens with x ≤ 0.52 had a rhombohedral structure.…”

“…2 Piezoelectric energy harvesters, which convert the wasted energy from mechanical vibrations into usable electrical energy, have been extensively investigated for use as power sources in wireless devices and various sensors. [3][4][5][6][7][8][9][10][11] Piezoelectric ceramics used in such devices should be capable of generating a considerable amount of electrical energy even for a small input vibration. The electrical energy density (u) produced by piezoelectric ceramics is generally expressed by the following equation: u = (1/2)(d ij 9g ij )(F/A), 12 where d ij is the piezoelectric strain constant; g ij is the piezoelectric voltage constant; F is the applied force; and A is the area of the specimen.…”

A Study on Important Issues for Estimating the Effectiveness of the Proposed Piezoelectric Energy Harvesters under Volume Constraints

“…The formula derived by Yang et al [15] was found to be exactly the same as the one introduced by Kim et al [14]. Shafer and Garcia [16] derived an expression for the average efficiency at the steady state by dividing the average harvested energy by the average change in the energy state of the system (heat losses + energy lost in damping + harvested energy). They reported that for the conservative case (heat losses = 0), their formula would be the same as the one proposed by Shu and Lien [13].…”

“…The output power of the vibration energy harvester is dependent on many factors and varies if the operation is on resonance or off resonance. Yang et al [15] Efficiency η 4 η 4 = rQk 2 1+k 2 rQ+ ω 2 r 2 Shafer and Garcia [16] Average efficiency η av…”

Piezoelectric Materials for Medical Applications

“…The main limitations of piezoelectric energy harvesting are low efficiency and power output. This is large concern with biomedical devices, because they often do not operate at the device's resonance frequency [115]. Another avenue of research focuses on enhancing the efficiency of energy harvesting by mechanically scraping screening charges found on the surface of piezoelectric materials [116][117][118][119].…”