Browsing by Author "Worthington, Emma"
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Item Open Access Analyses of Power Output of Piezoelectric Energy-Harvesting Devices Directly Connected to a Load Resistor Using a Coupled Piezoelectric-Circuit Finite Element Method(IEEE Institute of Electrical and Electronics, 2009-07-31T00:00:00Z) Zhu, Meiling; Worthington, Emma; Njuguna, James A. K.A coupled piezoelectric-circuit finite element model (CPC-FEM) is proposed for the first time to study the power output of a vibration-based piezoelectric vibration-based piezoelectric energy harvesting devices (EHDs) that is directly connected to a resistive load. Special focus is given to the effect of the resistive load value on the vibrational amplitude of the piezoelectric EHDs, and thus on the current, voltage, and power generated by the EHDs. In the literature, these outputs are widely assumed to be independent of the resistive load value for the reduction in complexity of modelling and simulation. The presented CPC-FEM uses a cantilever with sandwich structure and a seismic mass attached to the tip to study the following load characteristics of the EHD as a result of changing the resistive load value: (1) the electric outputs of the EHD: current through and voltage across the resistive load, (2) the power dissipated by the resistive load, (3) the vibration amplitude of tip displacement of the cantilever, and (4) the shift in resonant frequency of the cantilever. Investigation results shows significant dependences of the vibration characteristics of the piezoelectric EHDs on the externally connected resistive load are found, rather than independence as previously assumed in most literature. The CPC-FEM is capable of predicting the generated power output of the EHDs with different resistive load value while simultaneously calculating the effect of the resistive load value on the vibration amplitude. The CPC-FEM is invaluable for validating the performance of designed EHDs before fabrication and testing, thereby reducing the recurring costs associated with repeat fabrication and trials. In addition, the proposed CPC-FEM is potentially useful in device designs optimisations for maximal power generation.Item Open Access Coupled piezoelectric-circuit FEA to study influence of a resistive load on power output of piezoelectric energy devices(2012-08-01) Zhu, Meiling; Worthington, Emma; Njuguna, James A. K.; Schmid, UlrichThis paper presents, for the first time, a coupled piezoelectric-circuit finite element model (CPC-FEM) to analyze the power output of vibration-based piezoelectric energy harvesting devices (EHDs) when connected to a resistive load. Special focus is given to the effect of the resistive load value on the vibrational amplitude of the piezoelectric EHDs, and thus on the current, voltage, and power generated by the EHDs, which are normally assumed to be independent of the resistive load in order to reduce the complexity of modelling and simulation. The CPC-FEM presented uses a cantilever with the sandwich structure and a seismic mass attached to the tip to study the following load characteristics of the EHD as a result of changing the load resistor value: (1) the electric outputs of the EHD: current and voltage, (2) the power dissipated by the resistive load, (3) the vibration amplitude of tip displacement, and (4) the shift in resonant frequency of the cantilever. Significant dependences of the characteristics of the piezoelectric EHDs on the externally connected resistive load are found, rather than independency, as previously assumed in most literature. The CPC-FEM is capable of predicting the generated power output with different resistive load values while simultaneously considering the effect of the resistor value on the vibration amplitude. The CPC-FEM is invaluable for validating the performance of a device before fabrication and testing, thereby reducing the recurring costs associated with repeat fabrication and trials, and also for optimizing device design for maximal power-output generation.Item Open Access Design and testing of piezoelectric energy harvesting devices for generation of higher electric power for wireless sensor networks(2009-10-01T00:00:00Z) Zhu, Meiling; Worthington, EmmaThis paper reports our design and testing results on the electric output performance of a vibration-based piezoelectric energy harvesting device (PEHD). The PEHD is a cantilever with a sandwich structure and seismic mass attached to the tip. The geometric parameters of the device are based on optimization design with a volume of around 1cm3 and at a targeted resonant frequency of 80-100 Hz. A maximum output power of 370μW at 15.5 volts into a 325kΩ resistive load is generated at the resonant frequency of 87Hz and under an acceleration of 0.23g. Quite remarkably, this power is a very encouraging power figure that gives the prospect of being able to power a wider range of applications than is currently possible in wireless sensor networItem Open Access Piezoelectric Energy Harvesting: Enhancing Power Output by Device Optimisation and Circuit Techniques(Cranfield University, 2010-03-31) Worthington, Emma; Zhu, Meiling; Kirby, Paul B.Energy harvesting; that is, harvesting small amounts of energy from environmental sources such as solar, air flow or vibrations using small-scale (≈1cm 3 ) devices, offers the prospect of powering portable electronic devices such as GPS receivers and mobile phones, and sensing devices used in remote applications: wireless sensor nodes, without the use of batteries. Numerous studies have shown that power densities of energy harvesting devices can be hundreds of µW; however the literature also reveals that power requirements of many electronic devices are in the mW range. Therefore, a key challenge for the successful deployment of energy harvesting technology remains, in many cases, the provision of adequate power. This thesis aims to address this challenge by investigating two methods of enhancing the power output of a piezoelectric-based vibration energy harvesting device. Cont/d.