Vibration-based MEMS Piezoelectric Energy Harvester ... - IEEE Xplore
2013 UKSim 15th International Conference on Computer Modelling and Simulation
Vibration-based MEMS Piezoelectric Energy Harvester for Power Optimization Othman Sidek
Salem Saadon
Collaborative Microelectronic Design Excellence Center (CEDEC) Universiti Sains Malaysia (USM) Pinang, Malaysia [email protected]
School of Electrical and Electronic Engineering, (CEDEC) Universiti Sains Malaysia (USM), Pinang, Malaysia [email protected]
Abstract— The simplicity associated with piezoelectric micro-generators makes them very attractive for MEMS applications in which ambient vibrations are harvested and converted into electric energy. These micro-generators can become an alternative to the battery-based solutions in the future, especially for remote systems. In this paper, we propose a model and present the simulation of a MEMSbased energy harvester under ambient vibration excitation using the COVENTORWARE2010 approach. This E-shaped cantilever-based MEMS energy harvester that operates under ambient excitation in frequencies of 28, 29, and 31 Hz within a base acceleration of 1g produces an output power of 0.25 milliwatts at 5k load.
end with a small free end. They were proved mathematically that, a triangular piezoelectric cantilever having a base and height similar to the base and length of a rectangular piezoelectric cantilever can withstand a higher strain as well as maximum deflection for a given boundary conditions of the beam. Roundy et al. [21] discussed that, the strain is uniformly distributed throughout the trapezoidal cantilever structure than a rectangular cantilever, they stated that, a trapezoidal piezoelectric cantilever can generate more than twice the energy that can be generated by a rectangular piezoelectric cantilever, provided that both cantilevers contains the same volume of PZT. In this paper a new E-shaped unimorph cantilever was designed and simulated in order to provide an optimized power as well as effective strain using coventorware approaches.
Keywords —Piezoelectric materials, Energy conversion, shaped cantilever, MEMS
I.
INTRODUCTION
In the last view years, many researchers are focused on a various geometrical shape of piezoelectric cantilevers for the purpose of power optimization of the piezoelectric energy harvesters. In other words the requirements to maximize the harvested power within the variation of cantilever dimensions, weight and cost are the main challenge to maintain the power capability at ambient vibration frequencies. Previously, the rectangular shaped cantilevers were widely used according to their ease of fabrication, while the main disadvantage of such shape of cantilever is that the average strain is very poor. On the last decade, most researchers are focused on the piezoelectric materials and the operating modes of the harvester rather than the geometrical shapes of the cantilever [1-17]. Saadon and Sidek [18], were proposed a brief literature review on micro scale rectangular cantilevered piezoelectric harvesters, they showed that the power harvested is not enough to be applicable. Baker et al. [19], were examined the effects of the piezoelectric cantilever geometry on the power density in order to find a geometrical shape alternatives to the popular rectangular shape. Mateu and Moll [20] proposed an analytical comparison between a rectangular shape and triangular shaped piezoelectric cantilever having a large clamped
978-0-7695-4994-1/13 $26.00 © 2013 IEEE DOI 10.1109/UKSim.2013.153
II. FACTORS AFFECT THE OPTIMIZATION OF HARVESTED POWER To achieve an optimal output power of the cantilevered harvester, the resonant frequency should be taken into consideration. The dimensions of the cantilever and the mass decide the desirable resonant frequency of the harvester. Any slight deviation from the resonant frequency will cause a large reduction in the output power of such harvester. Thus, this resonant frequency should be calculated carefully to match the excitation frequency of the harvester and meet the optimal conditions for its output harvested power, which is the main objective of this paper. To determine the value of resonant frequency of any cantilevered piezoelectric energy harvester, important parameters should be defined from its structure as denoted on figure1.
Fig. 1. Typical MEMS-based cantilevered piezoelectric energy harvester
241
Usually, the resonant frequency of a piezoelectric cantilever expressed by Equation 2.1 [22]
the length or the width (w
Vibration-based MEMS Piezoelectric Energy Harvester for Power Optimization Othman Sidek
Salem Saadon
Collaborative Microelectronic Design Excellence Center (CEDEC) Universiti Sains Malaysia (USM) Pinang, Malaysia [email protected]
School of Electrical and Electronic Engineering, (CEDEC) Universiti Sains Malaysia (USM), Pinang, Malaysia [email protected]
Abstract— The simplicity associated with piezoelectric micro-generators makes them very attractive for MEMS applications in which ambient vibrations are harvested and converted into electric energy. These micro-generators can become an alternative to the battery-based solutions in the future, especially for remote systems. In this paper, we propose a model and present the simulation of a MEMSbased energy harvester under ambient vibration excitation using the COVENTORWARE2010 approach. This E-shaped cantilever-based MEMS energy harvester that operates under ambient excitation in frequencies of 28, 29, and 31 Hz within a base acceleration of 1g produces an output power of 0.25 milliwatts at 5k load.
end with a small free end. They were proved mathematically that, a triangular piezoelectric cantilever having a base and height similar to the base and length of a rectangular piezoelectric cantilever can withstand a higher strain as well as maximum deflection for a given boundary conditions of the beam. Roundy et al. [21] discussed that, the strain is uniformly distributed throughout the trapezoidal cantilever structure than a rectangular cantilever, they stated that, a trapezoidal piezoelectric cantilever can generate more than twice the energy that can be generated by a rectangular piezoelectric cantilever, provided that both cantilevers contains the same volume of PZT. In this paper a new E-shaped unimorph cantilever was designed and simulated in order to provide an optimized power as well as effective strain using coventorware approaches.
Keywords —Piezoelectric materials, Energy conversion, shaped cantilever, MEMS
I.
INTRODUCTION
In the last view years, many researchers are focused on a various geometrical shape of piezoelectric cantilevers for the purpose of power optimization of the piezoelectric energy harvesters. In other words the requirements to maximize the harvested power within the variation of cantilever dimensions, weight and cost are the main challenge to maintain the power capability at ambient vibration frequencies. Previously, the rectangular shaped cantilevers were widely used according to their ease of fabrication, while the main disadvantage of such shape of cantilever is that the average strain is very poor. On the last decade, most researchers are focused on the piezoelectric materials and the operating modes of the harvester rather than the geometrical shapes of the cantilever [1-17]. Saadon and Sidek [18], were proposed a brief literature review on micro scale rectangular cantilevered piezoelectric harvesters, they showed that the power harvested is not enough to be applicable. Baker et al. [19], were examined the effects of the piezoelectric cantilever geometry on the power density in order to find a geometrical shape alternatives to the popular rectangular shape. Mateu and Moll [20] proposed an analytical comparison between a rectangular shape and triangular shaped piezoelectric cantilever having a large clamped
978-0-7695-4994-1/13 $26.00 © 2013 IEEE DOI 10.1109/UKSim.2013.153
II. FACTORS AFFECT THE OPTIMIZATION OF HARVESTED POWER To achieve an optimal output power of the cantilevered harvester, the resonant frequency should be taken into consideration. The dimensions of the cantilever and the mass decide the desirable resonant frequency of the harvester. Any slight deviation from the resonant frequency will cause a large reduction in the output power of such harvester. Thus, this resonant frequency should be calculated carefully to match the excitation frequency of the harvester and meet the optimal conditions for its output harvested power, which is the main objective of this paper. To determine the value of resonant frequency of any cantilevered piezoelectric energy harvester, important parameters should be defined from its structure as denoted on figure1.
Fig. 1. Typical MEMS-based cantilevered piezoelectric energy harvester
241
Usually, the resonant frequency of a piezoelectric cantilever expressed by Equation 2.1 [22]
the length or the width (w
