Almuatasim Alomari

Enhanced piezoelectric energy harvester performance using magnetic force and thermal energy

ABSTRACT One possible approach of improving the performance of energy harvesters is to use energy harvester with an external magnetic force to create a nonlinear coupling system. In this work, we report experimental results of a single piezoelectric cantilever beam (PCB) with tip mass or conventional piezoelectric energy harvester (CPEH), and the effect of applying an external magnetic force. The output voltage and power at optimal resistance was 7.62 V and 0.62 mW, respectively, at the resonance frequency of approximately 11 Hz of a CPEH. Also, the output voltage and average power at optimal resistance was 8.56 V and 0.44 mW, respectively, at resonance frequency of 7 Hz of a PCB with fixed opposing magnet. Furthermore, the output voltage and average power at optimal resistance was 13.31 V and 1.77 mW, respectively, at resonance frequency of 11 Hz of a PCB with opposing magnet attached at a second cantilever. In addition, comparison between the experimental results of all different configurations showed a reasonable enhancement of performance of energy harvester when an external magnetic force added over the main PCB. Finally, the performance of a multisource energy harvester with magnetic, thermal and mechanical sources is also presented in this study. In this case, it is demonstrated that increase in output voltage with temperature gradient under effect of magnetic force; the results of 2nd and 3rd model showed 44% and 99% enhancement of its original output voltage value at 1.2 °C and 2.7 °C temperature difference, respectively.

Theoretical Background of Mechanical Energy Conversion

This chapter demonstrates the principles of a piezoelectric cantilever beam for vibration energy harvesting. There are multiple techniques for converting vibrational energy to electrical energy. The three dominant techniques are electrostatic, electromagnetic, and piezoelectric conversion. Numerous investigations have been performed recently on piezoelectric conversion due to the low difficulty of analysis and fabrication. In this chapter, the basics of Euler–Bernoulli beam model (EBM) analysis are explained briefly to calculate the resonance frequency of the cantilever beam under the transition and rotation conditions of the clamped end. In addition, the EBM is studied theoretically and applied under the harmonic excitation of a piezoelectric cantilever beam to predict the influence of the piezoelectric parameters and geometry on the output voltage and mode shapes. These predictions agree closely with the observed results mentioned in the literature.

Future Directions and Outlook

The process of acquiring the energy surrounding an energy system and converting it into usable electrical energy, i.e., power harvesting or scavenging,1 has seen a surge of interest in the last few years. This increase in research has been fostered by modern advances in wireless technology and low-power electronics, such as micro-electro-mechanical systems (MEMS). The advances have allowed numerous doors to open for power-harvesting systems in practical real world applications. The use of piezoelectric materials to capitalize on the ambient vibrations surrounding a system is one method that has seen a dramatic rise in use for power harvesting. Piezoelectric materials have a crystalline structure that provides them with the ability to transform mechanical strain energy into electrical charge and, conversely, convert an applied electrical potential into mechanical strain. This property allows these materials to absorb mechanical energy from their surroundings (usually ambient vibration) and transform it into electrical energy that can be used to power other devices. Vibration-based piezoelectricity is an attractive avenue for energy harvesting due to its robustness as well as its high power density and electromechanical coupling efficiency. Although piezoelectric materials represent the primary method of harvesting energy, other methods exist, e.g., the use of electromagnetic devices. The piezoelectric energy harvesters are a substitute for other alternative EH technologies, such as electromagnetic or thermoelectric energy, because they provide the consistent source of energy needed. The potential of generating electricity from piezoelectric harvesters is higher than alternative EH technologies, where the components of the device are capable of delivering over 65% of their charge. Section 10.1 discusses some of the research that has been performed in the area of power harvesting and the future goals that must be achieved for power-harvesting systems to find their way into everyday use.

Ferroelectric Energy Harvesting

Energy harvesting, or energy-scavenging technology, captures unused ambient energy—such as vibration, strain, light, temperature gradients and variations, gas flow energy, and liquid flow energy—and converts it into usable electrical energy. In spite of the advances made thus far, the batteries that power portable microelectronics and wireless devices provide only a finite amount of power. Energy harvesting is a perfect solution for the problem of finite battery power for various low-power applications: it provides sustained, cost-effective, and environmentally friendlier sources of power. In the recent past, unconventional methods for waste energy harvesting and scavenging were being explored to provide sustained power to these micro- and nano-devices. Efforts have been made to garner electric power from mechanical vibrations, light, spatial variations, and temporal temperature variations. Another potential source for low-power electronics is the waste thermal and mechanical energy of asphalt pavement, especially via pyroelectricity. However, to date, that potential has not been extensively explored (with the exception of the large-scale effort being made by Israel in paving kilometers of roads with a specially designed series of piezoelectric modules).

Energy harvesting under excitation of clamped-clamped beam

In this article, a piezoelectric energy harvesting has been developed experimentally and theoretically based on Euler- Bernoulli Theory. A PVDF piezoelectric thick film has attached along of clamped-clamped beam under sinusoidal base excitation of shaker. The results showed a good agreement between the experimental and simulation of suggested model. The voltage output frequency response function (FRF), current FRF, and output power has been studied under short and open circuit conditions at first vibration mode. The mode shape of the clamped-clamped beam for first three resonance frequency has been modeled and investigated using COMSOL Multiphysics and MATLAB.