Angela Triplett

The Effect of Non-linear Piezoelectric Coupling on Vibration-based Energy Harvesting

Advances in electronic and consumer technology are increasing the need for smaller, more efficient energy sources. Thus vibration-based energy harvesting, the scavenging of energy from existing ambient vibration sources and its conversion to useful electrical power, is becoming an increasingly attractive alternative to traditional power sources such as batteries. Energy harvesting devices have been developed based on a number of electromechanical coupling mechanisms and their design must be optimized to produce the maximum output for given environmental conditions. While the role of non-linearities in the components has been shown to be significant in terms of the overall device efficiency, few studies have systematically investigated their influence on the system performance. In this work the role of a non-linear piezoelectric relationship is considered on the performance of a vibration-based energy harvester. Using a Poincaré-Lindstedt perturbation analysis the response of the harvesting system is approximated, including mechanical damping, stiffness non-linearities, and the above mentioned non-linear piezoelectric constitutive relationship. The predicted behavior is then compared against numerical simulations of the original system, focusing on the relationship between the power generated by the device, the ambient vibration characteristics, and the non-linearities in the system.

Energy Harvesting From an Impulsive Load With Essential Nonlinearities

Vibration based energy harvesting, whereby mechanical energy is converted to electrical energy that can be stored and later used, offers the possibility of a long-term energy source under many realistic environmental conditions. This work considers an energy harvesting system based on the response of an attachment with strong nonlinear behavior. The electro-mechanical coupling is achieved with a piezo-electric element across a resistive load. When the system is subject to harmonic excitation, the harvested power from the nonlinear system exhibits a wider interval of frequencies over which the harvested power is significant, although an equivalent linear device offers greater efficiency at its design frequency. However, under impulsive excitation the performance of the nonlinear harvesting system exceeds the corresponding linear system in terms of both magnitude of power harvested and the frequency interval over which significant power can be drawn from the mechanical vibrations.Copyright

Experimental Investigation of Energy Harvesting With Essential Nonlinearities

The advancement of technology of portable electronics and devices has increased the need for self-sufficient energy sources. This work investigates the potentiality of a vibration-based energy harvesting system based on the response of an attachment with strong nonlinear behavior. The electromagnetic coupling is achieved by a piezoelectric element across a resistive load. Typical designs utilize a linear oscillator, which limits the peak harvesting performance to a narrow band of frequencies about the natural frequency of the oscillator. An essentially nonlinear cubic oscillator is shown, with proper design, to significantly improve the range of frequencies for sufficient harvesting when compared with a tuned linear oscillator design. Numerical simulations of the proposed model reveal this wider band of frequencies harvest significant power when the system is subjected to harmonic excitation. A physical model was developed and the acquired instantaneous voltage was recorded to calculate the average power over a resistive load and to experimentally validate the numerical simulations.Copyright

A Nonlinear System for Harvesting Energy From Sustained Low-Level Vibration

We address the conversion of mechanical energy from low-level ambient vibration into usable electrical energy. Development of this self-renewing energy source is vital to portable electronics and wireless sensors, especially since battery development has reached a plateau over the past decade. The passive nature of the proposed energy harvesting system provides for this self-renewing energy source. Conventional vibration energy harvesting systems are often based on linear elements, requiring specific tuning to achieve resonance and, thus, acceptable performance. This tuning is based on the predominant frequency of the ambient vibration. Linear energy harvesting systems are less desirable because ambient environmental conditions such as frequency content change with time, decreasing the performance of the system. This project focuses on the unique properties of a class of strongly nonlinear vibrating systems to effectively harvest energy under several excitation conditions. These excitations include low-level vibration from a wide range of environmental conditions including frequency content and low-level successive impulses at various frequencies. The later excitation condition is examined in this work. Numerical simulations of the proposed model, an essentially nonlinear oscillator with purely cubic stiffness attached to a larger grounded linear oscillator, have shown capture into sustained dynamic instability from successive low-level impulsive excitations. This sustained dynamic instability results in high energy harvesting efficiency. The electromechanical coupling is realized by a piezoelectric element in the mechanical system with voltage dissipated across a resistive load in the electrical system. This study focuses on characterizing the response of the system to varying parameters, such as fundamental period of the linear oscillator, impact frequency, and impact magnitude. An optimal fundamental period and impact frequency for dynamic instability are examined in this work. Analysis of the frequency-energy relation reveals the presence of sustained dynamic instability when the system operates under these specific parameters, leading to an optimized system for experimental validification.Copyright

Comparing Linear and Essentially Nonlinear Vibration-Based Energy Harvesting

Self-contained long-lasting energy sources are rapidly increasing in importance as portable electronics and inaccessible devices such as wireless sensors are finding wider and more varied applications. However, in many circumstances replacing power supplies, such as conventional batteries, becomes impractical and the development of a self-renewing source of energy is paramount to the continued development of such devices. The ability to convert ambient mechanical energy to usable electrical energy fills these requirements and one aspect of current research seeks to increase the efficiency and performance of these energy harvesting systems. However, to achieve acceptable performance conventional vibration-based energy harvesting devices based on linear elements must be specifically tuned to match environmental conditions such as the frequency and amplitude of the external vibration. As the environmental conditions vary under ambient conditions the performance of these linear devices is dramatically decreased. The strategy to efficiently harvest energy from low-level, intermittent ambient vibration, proposed herein, relies on the unique properties of a particular class of strongly nonlinear vibrating systems that are referred to as “essentially” nonlinear.© 2008 ASME

The Effect of Nonlinear Piezoelectric Coupling on Vibration-Based Energy Harvesting

Advances in electronic and consumer technology are increasing the need for smaller, more efficient energy sources. Thus vibration-based energy harvesting, the scavenging of energy from existing ambient vibration sources and its conversion to useful electrical power, is becoming an increasingly attractive alternative to traditional power sources such as batteries. Energy harvesting devices have been developed based on a number of electro-mechanical coupling mechanisms and their design must be optimized to produce the maximum output for given environmental conditions. While the role of nonlinearities in the components has been shown to be significant in terms of the overall device efficiency, few studies have systematically investigated their influence on the system performance. In this work the role of a nonlinear piezoelectric relationship is considered on the performance of a vibration-based energy harvester. Using a Poincare-Lindstedt perturbation analysis the response of the harvesting system is approximated, including mechanical damping, stiffness nonlinearities, and the above mentioned nonlinear piezoelectric constitutive relationship. The predicted behavior is then compared against numerical simulations of the original system, focusing on the relationship between the power generated by the device, the ambient vibration characteristics, and the nonlinearities in the system.Copyright