Imperial College London

DrStevenWright

Faculty of EngineeringDepartment of Electrical and Electronic Engineering

Teaching Fellow
 
 
 
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Contact

 

+44 (0)20 7594 6206s.wright02

 
 
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Location

 

1008BElectrical EngineeringSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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59 results found

Kiziroglou ME, Wright SW, Yeatman EM, 2021, Power supply based on inductive harvesting from structural currents, IEEE Internet of Things Journal, ISSN: 2327-4662

Monitoring infrastructure offers functional optimisation, lower maintenance cost, security, stability and data analysis benefits. Sensor nodes require some level of energy autonomy for reliable and cost-effective operation, and energy harvesting methods have been developed in the last two decades for this purpose. Here, a power supply that collects, stores and delivers regulated power from the stray magnetic field of currentcarrying structures is presented. In cm-scale structures the skin effect concentrates current at edges at frequencies even below 1 kHz. A coil-core inductive transducer is designed. A fluxfunnelling soft magnetic core shape is used, multiplying power density by the square of funnelling ratio. A power management circuit combining reactance cancellation, voltage doubling, rectification, super-capacitor storage and switched inductor voltage boosting and regulation is introduced. The power supply is characterised in house and on a full-size industrial setup, demonstrating a power reception density of 0.36 mW/cm3, 0.54 mW/cm3 and 0.73 mW/cm3 from a 25 A RMS structural current at 360 Hz, 500 Hz and 800 Hz respectively, corresponding to the frequency range of aircraft currents. The regulated output is tested under various loads and cold starting is demonstrated. The introduced method may enable power autonomy to wireless sensors deployed in current-carrying infrastructure.

Journal article

Pandiyan A, Boyle D, Kiziroglou M, Wright S, Yeatman Eet al., 2020, Optimal dynamic recharge scheduling for two stage wireless power transfer, IEEE Transactions on Industrial Informatics, Vol: 17, Pages: 5719-5729, ISSN: 1551-3203

Many Industrial Internet of Things applications require autonomous operation and incorporate devices in inaccessible locations. Recent advances in wireless power transfer (WPT) and autonomous vehicle technologies, in combination, have the potential to solve a number of residual problems concerning the maintenance of, and data collection from embedded devices. Equipping inexpensive unmanned aerial vehicles (UAV) and embedded devices with subsystems to facilitate WPT allows a UAV to become a viable mobile power delivery vehicle (PDV) and data collection agent. A key challenge is therefore to ensure that a PDV can optimally schedule power delivery across the network, such that it is as reliable and resource efficient as possible. To achieve this and out-perform naive on-demand recharging strategies, we propose a two-stage wireless power network (WPN) approach in which a large network of devices may be grouped into small clusters, where packets of energy inductively delivered to each cluster by the PDV are acoustically distributed to devices within the cluster. We describe a novel dynamic recharge scheduling algorithm that combines genetic weighted clustering with nearest neighbour search to jointly minimize PDV travel distance and WPT losses. The efficacy and performance of the algorithm are evaluated in simulation using experimentally derived traces, and the algorithm is shown to achieve 90% throughput for large, dense networks.

Journal article

Kiziroglou ME, Wright SW, Yeatman EM, 2020, Coil and core design for inductive energy receivers, Sensors and Actuators A: Physical, Vol: 313, Pages: 1-9, ISSN: 0924-4247

The design of coil/core transducers is important for maximizing the power density of inductive energy receivers for both inductive energy harvesting and power transfer. In this work, we present a study of core and coil performance, based on a simulated flux distribution corresponding to aircraft applications. The use of funnel-shaped soft magnetic cores boosts magnetic flux density by flux concentration and allows the use of a smaller diameter coil. This reduces the transducer mass as well as the coil resistance (RCOIL), thereby increasing the available power density. Analysis and simulation shows a fifty-fold power density increase from moderate funneling and another two-fold increase by coil size optimization. Results are compared with experimental measurements which demonstrate a 31 μW/g power density from alternating environmental magnetic fields in the 10 μT/360 Hz range.

Journal article

Kiziroglou ME, Wright SW, Yeatman EM, 2020, Shaped coil-core design for inductive energy collectors, 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Power MEMS), Publisher: IEEE, Pages: 1-4

Coil design is important for maximizing power density in inductive energy harvesting as well as in inductive power transfer. In this work, we present a study of coil performance, based on simulated flux distributions corresponding to a real aircraft application case. The use of funnel-shaped soft magnetic cores boosts magnetic flux density by flux concentration and allows the use of a smaller diameter coil. This reduces the transducer mass as well as the coil resistance (R COIL ), thereby increasing the power density. Analysis and simulation shows a fifty-fold power density increase from moderate funneling and another two-fold increase by coil size optimization. Results are compared with experimental measurements presented in [1] which demonstrate a 36μW/g(106μW/cm 3 ) power density from alternating environmental magnetic fields in the 10μT/300 Hz range.

Conference paper

Pandiyan AYS, Kiziroglou ME, Boyle DE, Wright SW, Yeatman EMet al., 2020, Optimal Energy Management of Two Stage Energy Distribution Systems Using Clustering Algorithm, 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Power MEMS), Publisher: IEEE

Conference paper

Wright S, Kiziroglou M, Spasic S, Nebojsa R, Yeatman Eet al., 2019, Inductive energy harvesting from current-carrying structures, IEEE Sensors Letters, Vol: 3, ISSN: 2475-1472

This article introduces an inductive method for harvesting energy from current-carrying structures. Numerical simulation of a structural beam shows that the skin effect can lead to significant current concentration at edges, providing a five-fold power benefit at such locations, even at frequencies below 1 kHz. The use of a rectangular ferrite core can provide a ×4 power density improvement. The adoption of funnel-like core shapes allows the reduction of core mass and coil frame size, leading to significant further power density enhancement. Magnetic field simulation and coil analysis demonstrate a power density increase of ×49 by ferrite funnels, in comparison to a coreless coil. Experimental results demonstrate rectified power over 1 mW delivered to a storage capacitor, from a 40 × 20 × 2 mm core-and-coil, in the vicinity of a spatially distributed 20 A current at 800 Hz. Rectification and impedance matching are studied experimentally using a voltage doubler circuit with input capacitor tuning to counteract the coil reactance. Experimental results from a spatially distributed 30 A current at 300 Hz and a 1:7 funnel core demonstrate power density of 36 μ W/g (103 μ W/cm 3 ), opening up the way to noninvasive inductive powering of systems in the vicinity of current-carrying structures.

Journal article

Boyle DE, Wright SW, Kiziroglou ME, Pandiyan AYS, Yeatman EMet al., 2019, Inductive Power Delivery with Acoustic Distribution to Wireless Sensors, Pages: 202-204

This paper proposes a new way to energize wireless sensors combining inductive power transfer with onward acoustic power distribution. Recent results showing inductive transfer of tens of watts from unmanned aerial vehicles to wireless sensors, in addition to acoustic propagation providing useful levels of transduced power, i.e. tens of mW, can be combined to form a hybrid wireless power transfer system for deeply embedded wireless sensors. Particular emphasis is placed on rectification efficiency for the acoustic receiver, finding that a minimum of 400 μW (for given parameters) are required to avoid excessive rectification losses, which is significant considering the finite energy available from the intermediate energy store.

Conference paper

Kiziroglou M, Wright S, Shi M, Boyle D, Becker T, Evans J, Yeatman Eet al., 2019, Milliwatt power supply by dynamic thermoelectric harvesting, PowerMEMS 2018, Publisher: Institute of Physics (IoP), Pages: 1-4, ISSN: 1742-6588

In this work we demonstrate a power supply that collects thermal energy from temperature fluctuations in time, to provide regulated power in the milliwatt range. It is based on the dynamic thermoelectric energy harvesting concept, in which a phase change material is used to store heat and create spatial heat flow from temperature transients. A simple, cost-effective and reproducible fabrication method is employed, based on 3D printing and off-the-shelf components. The harvester is integrated with a commercial power management module and supercapacitor storage. Output energy up to 2 J is demonstrated from temperature cycles corresponding to avionic applications. The demonstration includes harvesting while powering a 10 kΩ analogue voltmeter directly from the supercapacitor, including during cold-starting.

Conference paper

Allmen L, Bailleul G, Becker T, Decotignie J-D, Kiziroglou M, Leroux C, Mitcheson P, Muller J, Piguet D, Weisser A, Wright S, Yeatman Eet al., 2017, Aircraft strain WSN powered by heat storage harvesting, IEEE Transactions on Industrial Electronics, Vol: 64, Pages: 7284-7292, ISSN: 0278-0046

The combination of ultra-low-power wireless communications and energy harvesting enables the realization of autonomous wireless sensor networks. Such networks can be usefully applied in commercial aircraft where wireless sensing solutions contribute to weight reduction and increased ease of installation and maintenance. This paper presents, for the first time, a complete energy-autonomous wireless strain monitoring system for aircraft. The system is based on a multimode wireless time-division multiple access (TDMA) medium access control (MAC) protocol that supports automatic configuration and a time-stamping accuracy better than 1 ms. The energy supply depends solely on an innovative thermoelectric energy harvester, which takes advantage of the changes in environmental temperature during takeoff and landing. The system was successfully integrated and passed the functional and flight-clearance tests that qualify it for use in a flight-test installation.

Journal article

Kiziroglou M, Becker T, Wright SW, Yeatman EM, Evans JW, Wright PKet al., 2017, Three-Dimensional Printed Insulation For Dynamic Thermoelectric Harvesters With Encapsulated Phase Change Materials, IEEE Sensors Letters, Vol: 1, ISSN: 2475-1472

Energy harvesting devices have demonstrated their ability to provide power autonomy to wireless sensor networks. However, the adoption of such powering solutions by the industry is challenging due to their reliance on very specific environmental conditions such as vibration at a specific frequency, direct sunlight, or a local temperature difference. Dynamic thermoelectric harvesting has been shown to expand the applicability of thermoelectric generators by creating a local spatial temperature gradient from a temporal temperature fluctuation. Here, a simple method for prototyping or short-run production of such devices is introduced. It is based on the design and 3-D printing of an insulating container, insertion of a phase change material in encapsulated form, and use of commercial thermoelectric generators. The simplicity of this dry assembly method is demonstrated. Two prototype devices with double-wall insulation structures are fabricated, using a stainless-steel and a plastic phase change material encapsulation and a commercial TEG. Performance tests under a temperature cycle between ±25 °C show energy output of 43.6 and 32.1 J from total device masses of 69 and 50 g, respectively. Tests under multiple temperature cycles demonstrate the reliability and performance repeatability of such devices. The proposed method addresses the complication of requiring a wet stage during the final assembly of dynamic thermoelectric harvesters. It allows design and customization to particular size, energy, and insulation geometry requirements. This is important because it makes dynamic harvesting prototyping widely available and easy to reproduce, test, and integrate into systems with various energy requirements and size restrictions.

Journal article

Kiziroglou M, Boyle D, Wright S, Yeatman Eet al., 2017, Acoustic power delivery to pipeline monitoring wireless sensors, Ultrasonics, Vol: 77, Pages: 54-60, ISSN: 1874-9968

The use of energy harvesting for powering wireless sensors is made more challenging in most applications by the requirement for customization to each specific application environment because of specificities of the available energy form, such as precise location, direction and motion frequency, as well as the temporal variation and unpredictability of the energy source. Wireless power transfer from dedicated sources can overcome these difficulties, and in this work, the use of targeted ultrasonic power transfer as a possible method for remote powering of sensor nodes is investigated. A powering system for pipeline monitoring sensors is described and studied experimentally, with a pair of identical, non6inertial piezoelectric transducers used at the transmitter and receiver. Power transmission of 18 mW (Root6Mean6Square) through 1 m of a 118 mm diameter cast iron pipe, with 8 mm wall thickness is demonstrated. By analysis of the delay between transmission and reception, including reflections from the pipeline edges, a transmission speed of 1000 m/s is observed, corresponding to the phase velocity of the L(0,1) axial and F(1,1) radial modes of the pipe structure. A reduction of power delivery with water6filling is observed, yet over 4 mW of delivered power through a fully6filled pipe is demonstrated. The transmitted power and voltage levels exceed the requirements for efficient power management, including rectification at cold6starting conditions, and for the operation of low6power sensor nodes. The proposed powering technique may allow the implementation of energy autonomous wireless sensor systems for monitoring industrial and network pipeline infrastructure.

Journal article

Kiziroglou M, Becker T, Wright S, Yeatman EM, Evans J, Wright Pet al., 2016, Thermoelectric generator design in dynamic thermoelectricenergy harvesting, PowerMEMS 2016, Publisher: Institute of Physics (IoP), ISSN: 1742-6588

This paper reports an analysis of thermoelectric generator design for dynamic thermoelectric harvesting. In such devices, the available energy for a given temperature cycle is finite and determined by the heat storage unit capacity. It is shown by simulation and experimentally that specific thermoelectric generator designs can increase the energy output, by optimizing the balance between heat leakage and dynamic response delay. A 3D printed, doublewall heat storage unit is developed for the experiments. Output energy of 30 J from 7.5 gr of phase change material, from a temperature cycle between ± 22 °C is demonstrated, enough to supply typical duty-cycled wireless sensor platforms. These results may serve as guidelines for the design and fabrication of dynamic thermoelectric harvesters for applications involving environments with moderate temperature fluctuations.

Conference paper

Kiziroglou ME, Elefsiniotis A, Kokorakis N, Wright SW, Toh TT, Mitcheson PD, Schmid U, Becker T, Yeatman EMet al., 2016, Scaling and super-cooling in heat storage harvesting devices, Microsystem Technologies, Vol: 22, Pages: 1905-1914, ISSN: 0946-7076

Aircraft sensors are typically cable powered, imposing a significant weight overhead. The exploitation of temperature variations during flight by a phase change material (PCM) based heat storage thermoelectric energy harvester, as an alternative power source in aeronautical applications, has recently been flight tested. In this work, the applicability of this technology to use cases with smaller and larger size specifications is studied by fabrication, testing and analysis of a scaled-down and a scaled-up prototype. Output energy of 4.1 J/g of PCM from a typical flight cycle is demonstrated for the scaled-down device, and 2.3 J/g of PCM for the scaled-up device. The higher energy density of the scaled down prototypes is attributed to the reduction in temperature inhomogeneity inside the PCM. The impact of super-cooling on performance is analyzed by employing a simulation model extended to include super-cooling effects. It is found that super-cooling may be beneficial for scaling down, in applications with slow temperature fluctuations.

Journal article

Kiziroglou ME, Boyle D, Wright SW, Yeatman EMet al., 2015, Acoustic energy transmission in cast iron pipelines, The 15th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2015), Publisher: Institute of Physics (IoP), Pages: 1-5, ISSN: 1742-6588

In this paper we propose acoustic power transfer as a method for the remote powering of pipeline sensor nodes. A theoretical framework of acoustic power propagation in the ceramic transducers and the metal structures is drawn, based on the Mason equivalent circuit. The effect of mounting on the electrical response of piezoelectric transducers is studied experimentally. Using two identical transducer structures, power transmission of 0.33 mW through a 1 m long, 118 mm diameter cast iron pipe, with 8 mm wall thickness is demonstrated, at 1 V received voltage amplitude. A near-linear relationship between input and output voltage is observed. These results show that it is possible to deliver significant power to sensor nodes through acoustic waves in solid structures. The proposed method may enable the implementation of acoustic - powered wireless sensor nodes for structural and operation monitoring of pipeline infrastructure.

Conference paper

Kiziroglou ME, Elefsiniotis A, Kokorakis N, Wright SW, Toh TT, Mitcheson PD, Schmid U, Becker T, Yeatman EMet al., 2015, Scaling of dynamic thermoelectric harvesting devices in the 1-100 cm(3) range, Conference on Smart Sensors, Actuators, and MEMS VII 1st SPIE Conference on Cyber-Physical Systems, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X

Conference paper

Toh TT, Wright SW, Mitcheson PD, 2014, Resonant frequency tuning of an industrial vibration energy harvester, 14th International Conference on Micro- and Nano-Technology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588

Conference paper

Kiziroglou ME, Wright SW, Toh TT, Mitcheson PD, Becker T, Yeatman EMet al., 2014, Design and Fabrication of Heat Storage Thermoelectric Harvesting Devices, Industrial Electronics, IEEE Transactions on, Vol: 61, Pages: 302-309, ISSN: 0278-0046

Journal article

Toh TT, Wright SW, Kiziroglou ME, Mueller J, Sessinghaus M, Yeatman EM, Mitcheson PDet al., 2014, Inductive energy harvesting from variable frequency and amplitude aircraft power lines, ISSN: 1742-6596

Conference paper

Toh TT, Wright SW, Kiziroglou ME, Mitcheson PD, Yeatman EMet al., 2014, Inductive Energy Harvesting for Rotating Sensor Platforms, ISSN: 1742-6596

Conference paper

Toh TT, Wright SW, Kiziroglou ME, Mitcheson PD, Yeatman EMet al., 2014, A dual polarity, cold-starting interface circuit for heat storage energy harvesters, Sensors and Actuators A: Physical, Vol: 211, Pages: 38-44, ISSN: 0924-4247

Journal article

Kiziroglou ME, Elefsiniotis A, Wright SW, Toh TT, Mitcheson PD, Becker T, Yeatman EMet al., 2013, Performance of phase change materials for heat storage thermoelectric harvesting, Applied Physics Letters, Vol: 103, ISSN: 1077-3118

Heat storage energy harvesting devices have promise as independent power sources for wireless aircraft sensors. These generate energy from the temperature variation in time during flight. Previously reported devices use the phase change of water for heat storage, hence restricting applicability to instances with ground temperature above 0 °C. Here, we examine the use of alternative phase change materials (PCMs). A recently introduced numerical model is extended to include phase change inhomogeneity, and a PCM characterization method is proposed. A prototype device is presented, and two cases with phase changes at approximately −9.5 °C and +9.5 °C are studied.

Journal article

Toh TT, Wright SW, Kiziroglou ME, Yeatman EM, Mitcheson PDet al., 2013, Harvesting energy from aircraft power lines, Proceedings of the 1st International Workshop on Energy Neutral Sensing Systems, Publisher: ACM

Conference paper

Elefsiniotis A, Kiziroglou ME, Wright SW, Toh TT, Mitcheson PD, Becker T, Yeatman EM, Schmid Uet al., 2013, Performance evaluation of a thermoelectric energy harvesting device using various phase change materials, ISSN: 1742-6596

Conference paper

Wright SW, Judge CP, Lee MJ, Bowers DF, Dunbar M, Wilson CDet al., 2012, Thin film high dielectric constant metal oxides prepared by reactive sputtering, JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B, Vol: 30, ISSN: 2166-2746

Journal article

Kiziroglou ME, Wright SW, Toh TT, Becker T, Mitcheson PD, Yeatman EMet al., 2012, Heat Storage Power Supply for Wireless Aircraft Sensors, Pages: 472-475

Conference paper

Mukherjee AG, Mitcheson PD, Wright SW, Yeatman EMet al., 2012, Magnetic Potential Well Tuning of Resonant Frequency Cantilever Energy Harvesters, PowerMEMS 2012

Conference paper

Kaphengst NF, Toh TT, Mitcheson PD, Holmes AS, Wright SW, Yeatman EMet al., 2012, Adaptive Load Synthesis for Autonomous Resonant Frequency Tuning of Electromagnetic Energy Harvesters, PowerMEMS 2012

Conference paper

Mukherjee AG, Mitcheson PD, Wright SW, Yeatman EMet al., 2012, Tuning of vibration energy harvesters using variable reluctance links, Journal of Micromechanics and Microengineering

Journal article

Toh TT, Mitcheson PD, Dussud L, Wright SW, Holmes ASet al., 2011, Electronic Resonant Frequency Tuning of a Marine Energy Harvester, PowerMEMS 2011, Pages: 383-386

Conference paper

Wright SW, Judge CP, Lee MJ, Bowers DF, Dunbar M, Wilson CDet al., 2010, High sheet resistance, low temperature coefficient of resistance resistor films for integrated circuits, JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B, Vol: 28, Pages: 834-840, ISSN: 2166-2746

Journal article

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