Optimization of compact electromagnetic energy harvesters for wireless sensor applications

Yaşar, Oğuz
The developments in wireless sensor systems force researchers to analyze how to satisfy power requirements of these systems. Batteries can be the main candidate to be used as power source; however, they affect negatively the continuity of the wireless systems due to their limited lifetime. In order to provide continuous power source, energy harvester modules are proposed. With the advancements on IC technology, it is possible to convert extracted energies to power sources for the sensors operating in wireless environments. Therefore, the optimized design of the harvester to generate desired power for wireless sensor nodes is essential. The aim of this thesis study is to design, optimize, fabricate and test the electromagnetic (EM) energy harvesters to be used as power source for wireless systems. Since most of the vibrations in nature exist in low frequency levels (< 10 Hz), the proposed harvester should be capable of operating at low frequency and low amplitude vibrations. Additionally, the design should be compact enough is size; hence, device volume is limited with 8 cm3. This thesis study presents an optimization study for decreasing the operation frequency and increasing the output power of a miniature EM energy harvester. Incorporating a non-magnetic inertial mass (tungsten) along with the axially oriented moving magnets is the main strategy to reach optimum results. Dimensions of the magnets are optimized according to the harvester dimensions and magnetic flux gradients. Additionally, coil length, width, resistance and position have been optimized through finite element analysis (FEA) and experimentally validated. Simulation results show that using a single-magnet structure is not sufficient for increasing the output power of the system. Also, test results reveal that multi-magnet structures yield to higher output voltages and smaller resonance frequencies. Effects of the improvements on the moving structure are analyzed in detail and experimentally validated. The operation frequency of the harvester decreases with axially oriented moving magnets, while the output power increases due to greater magnetic flux contributions provided by repulsive forces. Compared to the single-magnet structure, a modified design with a similar size yields to a decrease in the resonance frequency (from 15 Hz to 7.2 Hz) and an increase in the output power. The optimized harvester has a volume of 7 cm3 and generates 0.53 VRMS, 266 µWRMS output power (@7.2 Hz and 0.5g peak acceleration). 


Wearable battery-less wireless sensor network with electromagnetic energy harvesting system
Chamanian, Salar; Ulusan, Hasan; Zorlu, Ozge; Baghaee, Sajjad; Uysal, Elif; Külah, Haluk (2016-10-01)
This paper presents a battery-less wireless sensor network (WSN) equipped with electromagnetic (EM) energy harvesters and sensor nodes with adjustable time-interval based on stored the energy. A wearable EM energy harvesting system is developed and optimized to power-up a typical wireless sensor mote from body motion. This is realized through characterization of the body motion and design of a compact EM energy harvester according to vibration frequencies generated during human running and walking. The harv...
Immune system-based energy efficient and reliable communication in wireless sensor networks
Atakan, Baris; Akan, Oezguer B. (2006-12-01)
Wireless sensor networks (WSNs) are event-based systems that rely on the collective effort of densely deployed sensor nodes. Due to the dense deployment, since sensor observations are spatially correlated with respect to location of sensor nodes, it may not be necessary for every sensor node to transmit its data. Therefore, due to the resource constraints of sensor nodes, it is imperative to select the minimum number of sensor nodes to transmit the data to the sink. Furthermore, to achieve the application-s...
Exploiting energy-aware spatial correlation in wireless sensor networks
Shah, Ghalib A.; Bozyigit, Muslim (2007-01-12)
Wireless sensor networks (WSNs) promise fine-grain monitoring in a wide variety of applications, which require dense sensor nodes deployment. Due to high density of nodes, spatially redundant or correlated data is generated. Redundancy increases the reliability level of information delivery but increases the energy consumption of the nodes too. Since energy conservation is a key issue for WSNs, therefore, spatial correlation can be exploited to deactivate some of the nodes generating redundant information. ...
Multi-objective evolutionary routing protocol for efficient coverage in mobile sensor networks
Attea, Bara'a A.; Khalil, Enan A.; Coşar, Ahmet (2015-10-01)
Individual sensors in wireless mobile sensor networks (MSNs) can move in search of coverage region for the sensing accuracy and for reaching the most efficient topology. Besides, sensors' clustering is crucial for achieving an efficient network performance. Although MSNs have been an area of many research efforts in recent years, integrating the coverage problem of MSNs with the efficient routing requirement that will maximize the network lifetime is still missing. In this paper, we consider the coverage op...
Powering-up Wireless Sensor Nodes Utilizing Rechargeable Batteries and an Electromagnetic Vibration Energy Harvesting System
Chamanian, Salar; Baghaee, Sajjad; Ulusan, Hasan; Zorlu, Ozge; Külah, Haluk; Uysal, Elif (2014-10-01)
This paper presents a wireless sensor node (WSN) system where an electromagnetic (EM) energy harvester is utilized for charging its rechargeable batteries while the system is operational. The capability and the performance of an in-house low-frequency EM energy harvester for charging rechargeable NiMH batteries were experimentally verified in comparison to a regular battery charger. Furthermore, the power consumption of MicaZ motes, used as the WSN, was evaluated in detail for different operation conditions...
Citation Formats
O. Yaşar, “Optimization of compact electromagnetic energy harvesters for wireless sensor applications,” M.S. - Master of Science, Middle East Technical University, 2017.