REMOVING THE RELIANCE ON BATTERIES: ENERGY HARVESTING BASED POWER SUPPLIES FOR RAIL AND WEARABLE APPLICATIONS
University of Southampton, UK
Harvesting energy from ambient sources has been researched over many years but the application of the technology can prove challenging. This talk will present the development of vibration energy harvesting and the search for an application of the technology that is commercially superior to batteries through the experience of Perpetuum Ltd. This concluded with a successful deployment in the rail industry where vibration energy harvesting is powering retrofittable wireless condition monitor systems around the world. The talk will then look to future applications in flexible and wearable applications where conventional batteries are highly undesirable. A wide variety of energy sources will be presented including kinetic, thermal, solar and wireless power transfer and the opportunities for energy harvesting powered e-textile systems will be explored.
ENERGY HARVESTING FROM A CONTROL-THEORETIC PERSPECTIVE
University of Michigan, USA
A fundamental aspect of all vibration energy-harvesting technologies concerns the influence of power generation on the harvester dynamics. Usually, this concept is characterized by the damping introduced into the harvester dynamics by the power extraction circuit, and this interpretation leads to many popular design techniques for the optimization of power extraction circuits. However, we may view this concept more generally as the introduction of feedback into the harvester dynamics, and there is consequently an intimate connection between energy harvesting and control theory. Indeed, for energy-harvesting technologies at larger power scales (such as ocean wave energy converters, regenerative vehicle suspensions, and self-powered structural control systems) control theory plays a central role in performance optimization. In applications where disturbances are stationary and stochastic, the harvester dynamics are linear, the power flow of the harvesting electronics is unconstrained, and the conductive losses of the harvesting circuit are ohmic, power generation is optimized via classical Linear Quadratic Gaussian techniques. For small-scale energy harvesting technologies, at least one of these assumptions is usually unjustified. In these cases, control theory can still be used to optimize harvested power, but more advanced techniques are required. In this talk, I consider some of the technological limitations and constraints of small-scale energy harvesting circuits in the context of feedback control design. In particular, I will discuss how power directionality constraints, complex parasitic losses, and limitations on feedback complexity can be accommodated. I will also illustrate that, even if control theory is not used to optimize a harvesting circuit, it is still useful as a means of finding the fundamental limits on power generation performance.
NOVEL BEAM FORMING TECHNOLOGY OF WIRELESS POWER FOR MILLIWATT COMMERCIAL APPLICATION AND GIGA WATT APPLICATION IN SPACE
Kyoto University, JAPAN
In Japan, there is a long history of a reseach and development of a far field wireless power transfer (WPT) and also recent novel technologies of the WPT. We establied a new radio regulation of the far field WPT in last May in Japan. It's currently for low power application only, e.g. battery-free IoT sensors, low power display, etc. To make it more convenient, we need to increase received power in cosideration with human safty and supressing interferrence. The beam forming technology can solve the problem. In this talk, I introduce R&D project of the novel beam forming in Japan. This can be applied for huge wireless power from space to ground, which is called a Solar Power Satellite (SPS). I also introduce ongoing Japanese WPT satellite project for the SPS.
CIRCUIT THEORY INSPIRED SOLUTIONS FOR ENERGY HARVESTING APPLICATIONS
Politecnico di Torino, Torino, ITALY
In this work, we propose and analyze two solutions, inspired from circuit theory, to design energy harvesters with improved performances [1,2]. The pros and cons of both solutions are discussed, and their ideal application range is outlined. Our theoretical and numerical analysis shows that the proposed solutions outperform traditional energy harvesting systems both in terms of harvested power and of power efficiency.
TRIBOELECTRICITY: FUNDAMENTALS AND APPLICATIONS
Purdue University, USA
This presentation will discuss new research on the principles of triboelectrity, or contact electrification, and its potential applications in vibration detection and suppression. Contact electrification of solids in a gas medium occurs in two stages: surface charge deposition immediately after separation and dissipation owing to medium dielectric breakdown as the gap widens. The generally accepted but unproven assumption that such gas breakdown obeys Paschen's law, which is routinely derived for gas between electrodes with a constant charge supply, is widely accepted but unproven. The current study experimentally establishes such a relationship between the breakdown voltage of air between charged dielectric surfaces and its pressure and gap distance. In a vacuum chamber, sample surfaces are subjected to contact electrification cycles, and charge relaxation owing to air breakdown is monitored using Coulomb attraction measurements by fixing one and adjusting the other. The findings indicate pressure and distance thresholds for investigating the raw amount of charge transfer prior to any breakdown discharge, which are used to investigate the saturation trend of surface charge density in the contact electrification of multiple material combinations using the same test apparatus. Repeated experiments on a range of contact pairings produce largely consistent findings. Conclusions about the general raw level of surface charge density and the air breakdown during separation in contact electrification are used to improve models of vibro-impact triboelectric energy harvesters, allowing their performance to be predicted under a variety of air pressures and physical dimensions. This is done to either prevent air breakdown or boost power production.
CONCEPT DESIGNS FOR VIBRATION ENERGY HARVESTING EMPLOYING NONLINEAR DYNAMICS
Loughborough University, UK
The era of Industrial Internet of Things requires the development of broadband energy harvesters with the capability to energize low-power electronics for self-powered sensing applications. Although miniaturised vibration energy harvesters can provide an energy source for wireless sensing, major challenges are the energy harvesting capability, bandwidth, device size and reliability in harnessing broadband energy sources. The use of nonlinear dynamics features can play a key role in the design of the mechanical part of the harvester in order to increase its performance. Some fundamentals and methods adopted for this purpose are discussed in this seminar.