An Integrated Approach to Energy Harvester Modeling and Performance Optimization

This paper proposes an integrated approach to energy harvester (EH) modeling and performance optimization where the complete mixed physical-domain EH (micro generator, voltage booster, storage element and load) can be modeled and optimized. We show that electrical equivalent models of the micro generator are inadequate for accurate prediction of the voltage booster’s performance. Through the use of hardware description language (HDL) we demonstrate that modeling the micro generator with analytical equations in the mechanical and magnetic domains provide an accurate model which has been validated in practice. Another key feature of the integrated approach is that it facilitates the incorporation of performance enhanced optimization, which as will be demonstrated is necessary due to the mechanicalelectrical interactions of an EH. A case study of a state-of-the-art vibration-based electromagnetic EH has been presented. We show that performance optimization can increase the energy harvesting rate by about 40%

Optimization of an Electromagnetic Energy Harvesting Device

This paper presents the modeling and optimization of an electromagnetic-based generator for generating power from ambient vibrations. Basic equations describing such generators are presented and the conditions for maximum power generation are described. Two-centimeter scale prototype generators, which consist of magnets suspended on a beam vibrating relative to a coil, have been built and tested. The measured power and modeled results are compared. It is shown that the experimental results confirm the optimization theory

Parylene-based electret power generators

n electret power generator is developed using a new electret made of a charged parylene HT® thin-film polymer. Here, parylene HT® is a room-temperature chemical-vapor-deposited thin-film polymer that is MEMS and CMOS compatible. With corona charge implantation, the surface charge density of parylene HT® is measured as high as 3.69 mC m^−2. Moreover, it is found that, with annealing at 400 °C for 1 h before charge implantation, both the long-term stability and the high-temperature reliability of the electret are improved. For the generator, a new design of the stator/rotor is also developed. The new micro electret generator does not require any sophisticated gap-controlling structure such as tethers. With the conformal coating capability of parylene HT®, it is also feasible to have the electret on the rotors, which is made of either a piece of metal or an insulator. The maximum power output, 17.98 µW, is obtained at 50 Hz with an external load of 80 MΩ. For low frequencies, the generator can harvest 7.7 µW at 10 Hz and 8.23 µW at 20 Hz

Design, fabrication and test of integrated micro-scale vibration based electromagnetic generator

This paper discusses the design, fabrication and testing of electromagnetic microgenerators. Three different designs of power generators are partially microfabricated and assembled. Prototype A having a wire-wound copper coil, Prototype B, an electrodeposited copper coil both on a Deep Reactive Ion etched (DRIE) silicon, beam and paddle. Prototype C uses moving NdFeB magnets in between two microfabricated coils. The integrated coil, paddle and beam were fabricated using standard micro-Electro-Mechanical Systems (MEMS) processing techniques. For Prototype A, the maximum measured power output was 148 nW at 8.08 kHz resonant frequency and 3.9 m/s2 acceleration. For prototype B, the microgenerator gave a maximum load power of 23 nW for an acceleration of 9.8 m/s2, at a resonant frequency of 9.83 kHz. This is a substantial improvement in power generated over other microfabricated silicon based generators reported in literature. This generator has a volume of 0.1 cm3 which is lowest of all the silicon based microfabricated electromagnetic power generators reported. To verify the potential of integrated coils in electromagnetic generators, Prototype C was assembled. This generated a maximum load power of 5

Classification of multiple electromagnetic interference events in high-voltage power plant

This paper addresses condition assessment of electrical assets contained in high voltage power plants. Our work introduces a novel analysis approach of multiple event signals related to faults, and which are measured using Electro-Magnetic Interference method. The proposed method transfers the expert’s knowledge on events presence in the signals to an intelligent system which could potentially be used for automatic EMI diagnosis. Cyclic spectrum analysis is used as feature extraction to efficiently extract the repetitive rate and the dynamic discharge level of the events, and multi-class support vector machine is adopted for their classification. This first and novel method achieved successful results which may have potential implications on developing a framework for automatic diagnosis tool of EMI events

Integrated approach to energy harvester mixed technology modelling and performance optimisation

An energy harvester is a system consisting of several components from different physical domains including mechanical, magnetic and electrical as well as the external circuits which regulate and store the generated energy. To design highly efficient energy harvesters, we believe that the various components of the energy harvesters need to be modelled together and in systematic manner using one simulation platform. We propose an accurate HDL model for the energy harvester and demonstrate its accuracy by validating it experimentally and comparing it with recently reported models. It is crucial to consider the various parts of the energy harvester in the context of a complete system, or else the gain at one part may come at the price of efficiency loss else where, rending the energy harvester much less efficient than before. The close mechanical-electrical interaction that takes place in energy harvesters, often lead to significant performance loss when the various parts of the energy harvesters are combined. Therefore, to address the performance loss, we propose an integrated approach to the energy harvester modelling and performance optimisation and demonstrate the effectiveness of employing such an approach by showing that it is possible to improve the performance of vibration-based energy harvester, in terms of the effective energy stored in the super-capacitor, by 33% through optimising the micro-generator mechanical parameters and the voltage booster circuit components

A low-power, linear, permanent-magnet generator/energy storage system

This paper describes the design, analysis and characterization of a linear permanent magnet generator and capacitive energy storage system for generating electrical power from a single stroke of a salient-pole armature. It is suitable for applications that require relatively low levels of electrical power, such as remote electronic locks. An electromagnetic analysis of the generator is described, and a design optimization methodology for the system is presented. Finally, the performance of a prototype is validated against measurement

On the performance and resonant frequency of electromagnetic induction energy harvesters

This paper investigates the linear response of an archetypal energy harvester that uses electromagnetic induction to convert ambient vibration into electrical energy. In contrast with most prior works, the in uence of the circuit inductance is not assumed negligible. Instead, we highlight parameter regimes where the inductance can alter resonance and derive an expression for the resonant frequency. The governing equations consider the case of a vibratory generator directly powering a resistive load. These equations are non-dimensionalized and analytical solutions are obtained for the system's response to single harmonic, periodic, and stochastic environmental excitations. The presented analytical solutions are then used to study the power delivered to an electrical load