Publications
191 results found
Rajaguru P, Bailey C, Lu H, et al., 2017, Co-Design/Simulation of Flip-Chip Assembly for High Voltage IGBT Packages, 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC), Publisher: IEEE
Boyle D, Kiziroglou ME, Mitcheson P, et al., 2016, Energy provision and storage for pervasive computing, IEEE Pervasive Computing, Vol: 15, Pages: 28-35, ISSN: 1536-1268
Soon, pervasive computers will enormously outnumber humans. Devices requiring sufficient energy to operate maintenance-free for periods of years and beyond render today's technologies insufficient. With the gap between energy requirements of embedded systems and achievable levels of harvested power reducing, viable hybrid energy and power management subsystems have emerged that combine harvesting with finite, rechargeable energy buffers. Coupled with advances in wireless power transfer and energy storage, the authors suggest that an energy design space is emerging. There are, as yet, no tools or systematic methods for design space exploration or engineering in this context. It's important to develop such a methodology, and critical to link it with methodologies for system design and verification. The authors discuss key factors such an energy design methodology should incorporate, including size, weight, energy and power densities; mobility; efficiencies of harvesters and buffers; time between charges, (dis)charge speeds, and charge cycles; and availability and predictability of harvestable energy. This article is part of a special issue on energy harvesting.
Merlin MMC, mitcheson PD, 2016, Active power losses distribution methods for the modular multilevel converter, COMPEL 2016, Publisher: IEEE, ISSN: 1093-5142
Modular Converters such as the MMC have become the new standard in VSC-HVDC applications. Their modularity has brought many industrial advantages but also increased the complexity of their operation. This paper looks at how a range of techniques may alter the balance of power losses between the IGBT modules. These techniques are based on circulating currents at the (i) fundamental frequency and (ii) second harmonic and (iii) DC voltage offset on the converter voltage waveform. Finally, conclusions on the effectiveness and potential drawbacks of these techniques are discussed.
Arteaga JM, Kkelis G, Yates DC, et al., 2016, A current driven Class D rectifier with a resistance compression network for 6.78MHz IPT systems, IEEE Wireless Power Transfer Conference (WPTC), Publisher: IEEE, Pages: 1-4, ISSN: 2474-0225
In maximal link efficiency IPT design, a fixed AC load value is required. For this reason, matching the value of the input impedance of the rectifier to the optimal AC load is necessary. This paper presents a current driven Class D rectifier with a resistance compression network for 6.78MHz IPT systems, in which the reflected AC load has a minimal variation for a wide range of DC output loads. Experimental results showed a resistance deviation of 31% for an output DC load varying from 10Ω to 80Ω while maintaining high efficiency. Recorded receiving end efficiency range from 96.5% to 88.2%. The achieved compression in resistance deviation could potentially maintain the efficiency of the hosting inductive link above 95%.
Mitcheson PD, Lucyszyn S, Pinuela M, et al., 2016, RF energy harvester, US9837865B2
Disclosed herein is an antenna apparatus for use in harvesting ambient radio frequency, RF, energy. The apparatus comprises one or more RF antenna components arranged to receive RF energy for producing electricity. The one or more RF antenna components comprise a plurality of frequency filtering components, each frequency filtering component being arranged to filter a respective frequency band of the received RF energy. Also disclosed herein is an apparatus comprising a rectifying circuit arranged to convert a variable electrical signal received at an input from an associated antenna into a direct current electrical signal for supplying to an electrical energy storage unit, the antenna for use in harvesting ambient radio frequency, RF, energy. The apparatus also comprises a power management module having an input arranged to receive the direct current and control supply of the direct current to the electrical energy storage unit. The rectifying circuit comprises a plurality of transmission lines, wherein the input of the rectifying circuit and the input of the power management module are connected via the plurality of transmission lines. The power management module is arranged at least partially within a boundary defined by the plurality of transmission lines.
Miller LM, Elliott ADT, Mitcheson PD, et al., 2016, Maximum performance of piezoelectric energy harvesters when coupled to interface circuits, IEEE Sensors Journal, Vol: 16, Pages: 4803-4815, ISSN: 1530-437X
This paper presents a complete optimization of a piezoelectric vibration energy harvesting system, including a piezoelectric transducer, a power conditioning circuit with full semiconductor device models, a battery and passive components. To the authors awareness, this is the first time and all of these elements have been integrated into one optimization. The optimization is done within a framework, which models the combined mechanical and electrical elements of a complete piezoelectric vibration energy harvesting system. To realize the optimization, an optimal electrical damping is achieved using a single-supply pre-biasing circuit with a buck converter to charge the battery. The model is implemented in MATLAB and verified in SPICE. The results of the full system model are used to find the mechanical and electrical system parameters required to maximize the power output. The model, therefore, yields the upper bound of the output power and the system effectiveness of complete piezoelectric energy harvesting systems and, hence, provides both a benchmark for assessing the effectiveness of existing harvesters and a framework to design the optimized harvesters. It is also shown that the increased acceleration does not always result in increased power generation as a larger damping force is required, forcing a geometry change of the harvester to avoid exceeding the piezoelectric breakdown voltage. Similarly, increasing available volume may not result in the increased power generation because of the difficulty of resonating the beam at certain frequencies whilst utilizing the entire volume. A maximum system effectiveness of 48% is shown to be achievable at 100 Hz for a 3.38-cm3 generator.
Kwan CH, Pinuela M, Mitcheson P, et al., 2016, Inductive power transfer system, WO2016050633 A3
There is provided a near-field inductive power transfer system (10), comprising a power transmission device (100) arranged to transmit power wirelessly at a first frequency, f0, and a power reception device (200) arranged to receive power transmitted by the power transmission device (100). The power reception device (200) is moveable relative to the power transmission device (100) and comprises a receiver circuit (210) configured to receive power for powering a variable load (230) when the power reception device (200) is in a near-field region of the power transmission device (100), the receiver circuit being a resonant circuit with a resonant frequency, fR, such that 0.2 < f0/fR < 3. The power reception device (200) also includes an impedance emulator (220) for providing the received power to the variable load (230), the impedance emulator being arranged to suppress a variation in an impedance presented to the receiver circuit (210) by the load when the load varies during use of the near-field inductive power transfer system (10).
Aldhaher S, Mitcheson PD, Yates DC, 2016, Load-independent Class EF inverters for inductive wireless power transfer, 2016 IEEE Wireless Power Transfer Conference (WPTC), Publisher: IEEE
This paper will present the modelling, analysis and design of a load-independent Class EF inverter. This inverter is able to maintain zero-voltage switching (ZVS) operation and produce a constant output current for any load value without the need for tuning or replacement of components. The load-independent feature of this inverter is beneficial when used as the primary coil driver in multi megahertz high power inductive wireless power transfer (WPT) applications where the distance between the coils and the load are variable. The work here begins with the traditional load-dependent Class EF topology for inversion and then specifies the criteria that are required to be met in order achieve load-independence. The design and development of a 240W load-independent Class EF inverter to drive the primary coil of a 6.78MHz WPT system will be discussed and experimental results will be presented to show the load-independence feature when the distance between the coils of the WPT system changes.
Aldhaher S, Mitcheson PD, Yates DC, 2016, Design and Development of a Class EF<sub>2</sub> Inverter and Rectifier for Multi-megahertz Wireless Power Transfer Systems, IEEE Transactions on Power Electronics, Vol: 31, Pages: 8138-8150, ISSN: 1941-0107
This paper presents the design and implementation of a Class EF2 inverter and Class EF2 rectifier for two -W wireless power transfer (WPT) systems, one operating at 6.78 MHz and the other at 27.12 MHz. It will be shown that the Class EF2 circuits can be designed to have beneficial features for WPT applications such as reduced second-harmonic component and lower total harmonic distortion, higher power-output capability, reduction in magnetic core requirements and operation at higher frequencies in rectification compared to other circuit topologies. A model will first be presented to analyze the circuits and to derive values of its components to achieve optimum switching operation. Additional analysis regarding harmonic content, magnetic core requirements and open-circuit protection will also be performed. The design and implementation process of the two Class-EF2-based WPT systems will be discussed and compared to an equivalent Class-E-based WPT system. Experimental results will be provided to confirm validity of the analysis. A dc-dc efficiency of 75% was achieved with Class-EF2-based systems.
Kiziroglou ME, Elefsiniotis A, Kokorakis N, et 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.
Hui SYR, Mitcheson PD, 2016, Wireless power transfer, Power Electronic Converters and Systems: Frontiers and Applications, Pages: 577-600, ISBN: 9781849198264
WPT can be broadly classified as radiative and non-radiative. Power can be radiated by an antenna and propagates through a medium such as air in the form of a radio frequency (RF) electromagnetic wave. Non-radiative WPT is based on near-field magnetic coupling of magnetic circuits that are generally in the form of conductive loops with a resonant frequency. WPT can be achieved through a range of technologies, ranging from near-field magnetic coupling based technologies operating at a relatively low frequency (such as 10 kHz-15.65 MHz) to microwave technologies operating at relatively high frequency (up to a few giga-hertz). This chapter focuses primarily on the former type of research and applications based on near-field magnetic coupling. It covers WPT research and applications from low-power applications.
Douthwaite M, Moser N, Koutsos E, et al., 2016, A CMOS ISFET Array for Wearable Thermoelectrically Powered Perspiration Analysis, 12th IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, Pages: 54-57, ISSN: 2163-4025
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- Citations: 3
Kwan CH, Yates DC, Mitcheson PD, 2016, Design Objectives and Power Limitations of Human Implantable Wireless Power Transfer Systems, IEEE Wireless Power Transfer Conference (WPTC), Publisher: IEEE, ISSN: 2474-0225
Yates DC, Aldhaher S, Mitcheson PD, 2016, Design of 3 MHz DC/AC Inverter with Resonant Gate Drive for a 3.3 kW EV WPT System, 2nd IEEE Annual Southern Power Electronics Conference (SPEC), Publisher: IEEE
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- Citations: 5
Yates DC, Aldhaher S, Mitcheson PD, 2016, A 100-W 94% Efficient 6-MHz SiC Class E Inverter with a Sub 2-W GaN Resonant Gate Drive for IPT, IEEE Wireless Power Transfer Conference (WPTC), Publisher: IEEE, ISSN: 2474-0225
Elliott ADT, Caccia A, Thomas A, et al., 2016, Shared inductor hybrid topology for weight constrained piezoelectric actuators, 16th International Conference on Micro- and Nano-Technology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Kkelis G, Yates DC, Mitcheson PD, 2016, Hybrid Class-E Low dv/dt Rectifier for High Frequency Inductive Power Transfer, IEEE Wireless Power Transfer Conference (WPTC), Publisher: IEEE, ISSN: 2474-0225
Aldhaher S, yates D, Mitcheson P, 2015, Modelling and Analysis of Class EF and Class E/F Inverters with series-tuned resonant networks, IEEE Transactions on Power Electronics, Vol: 31, Pages: 3415-3430, ISSN: 0885-8993
Class EF and Class E/F inverters are hybrid inverters that combine the improved switch voltage and current waveforms of Class F and Class F-1 inverters with the efficient switching of Class E inverters. As a result, their efficiency, output power and power output capability can be higher in some cases than the Class E inverter. Little is known about these inverters and no attempt has been made to provide an in depth analysis on their performance. The design equations that have been previously derived are limited and are only applicable under certain assumptions. This paper is the first to provide a comprehensive set of analytical analysis of Class EF and Class E/F inverters. The Class EF2 inverter is then studied in further detail and three special operation cases are defined that allow it to either operate at maximum power-output capability, maximum switching frequency or maximum output power. Final design equations are provided to allow for rapid design and development. Experimental results are provided to confirm the accuracy of the performed analysis based on a 23W Class EF2 inverter at 6.78MHz and 8.60MHz switching frequencies. The results also show that the Class EF2 inverter achieved an efficiency of 91% compared to a 88% efficiency when operated as a Class E inverter.
Mitcheson PD, Lucyszyn S, Pinuela M, et al., 2015, Inductive power transfer system, US9899877B2
An inductive power transfer system comprises a transmitter circuit comprising a transmitter coil and a receiver circuit comprising a receiver coil spaced from the transmitter coil. The transmitter circuit is in the form of a Class E amplifier with a first inductor and a transistor in series between the terminals of a power supply. A first transmitter capacitance is in parallel with the transistor between the first inductor and a power supply terminal, a primary tank circuit in parallel with the first transmitter capacitance, the primary tank circuit comprising the transmitter coil and a second transmitter capacitance arranged in parallel with the transmitter coil, and a third transmitter capacitance in series with the first inductor between the first transmitter capacitance and the primary tank circuit. The second transmitter capacitance is selected such that a resonant frequency of the primary tank circuit is not equal to the first frequency.
Kwan CH, Kkelis G, Aldhaher S, et al., 2015, Link efficiency-led design of mid-range inductive power transfer systems, Pages: 1-7
Aldhaher S, Kkelis G, Yates DC, et al., 2015, Class EF2 inverters for wireless power transfer applications, Pages: 1-4
Bowden JA, Burrow SG, Cammarano A, et al., 2015, Switched-Mode Load Impedance Synthesis to Parametrically Tune Electromagnetic Vibration Energy Harvesters, IEEE-ASME TRANSACTIONS ON MECHATRONICS, Vol: 20, Pages: 603-610, ISSN: 1083-4435
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- Citations: 30
Feldman J, Hanrahan BM, Misra S, et al., 2015, Vibration-Based Diagnostics for Rotary MEMS, JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, Vol: 24, Pages: 289-299, ISSN: 1057-7157
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- Citations: 7
Lawson J, Mitcheson PD, Yates DC, 2015, Efficient artificial magnetic conductor shield for wireless power, Wireless Power Transfer Conference (WPTC), 2015 IEEE
Artificial magnetic conductors (AMC) offer a solu-tion to increasing link efficiency in inductive power transfer (IPT)while reducing magnetic fields outside the air gap. A practicaldesign for an artificial magnetic conductor, suitable for use asa shield for inductive power transfer, is presented. The AMCmakes use of a ferrite substrate and lumped capacitor loading. Amodel of the plane wave behaviour of the structure is comparedto simulation and the performance of the AMC compared toother shielding solutions, in an IPT scenario. The plane wavebehaviour is found not to provide a good prediction of the AMCbehaviour in the IPT scenario. The AMC shield is found to offerthe greatest link efficiency, in the IPT scenario.
Kiziroglou ME, Elefsiniotis A, Kokorakis N, et al., 2015, Scaling of dynamic thermoelectric harvesting devices in the 1-100 cm<SUP>3</SUP> 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
Kkelis G, Yates DC, Mitcheson PD, 2015, Comparison of Current Driven Class-D and Class-E Half-Wave Rectifiers for 6.78 MHz High Power IPT Applications, 3rd IEEE Wireless Power Transfer Conference (WPTC), Publisher: IEEE
Elliott ADT, Miller LM, Halvorsen E, et al., 2015, Which is better, electrostatic or piezoelectric energy harvesting systems?, 15th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
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- Citations: 7
Clerckx B, Bayguzina E, Yates DC, et al., 2015, Waveform optimization for Wireless Power Transfer with nonlinear energy harvester modeling., Publisher: IEEE, Pages: 276-280
Mitcheson PD, 2015, ALTERNATIVE POWER SOURCES FOR MINIATURE AND MICRO DEVICES, 18th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), Publisher: IEEE, Pages: 928-933
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- Citations: 3
Clerckx B, Bayguzina E, Yates D, et al., 2015, Waveform Optimization for Wireless Power Transfer with Nonlinear Energy Harvester Modeling, 2015 12TH INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATION SYSTEMS (ISWCS)
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