Publications
191 results found
Frost T, Mitcheson PD, Green TC, 2015, Power Electronic Voltage Regulation In LV Distribution Networks, IEEE 6th International Symposium on Power Electronics for Distributed Generation Systems (PEDG), Publisher: IEEE, Pages: 127-133, ISSN: 2329-5759
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- Citations: 2
Howey DA, Yufit V, Mitcheson PD, et al., 2014, Impedance measurement for advanced battery management systems
We present a fast, low-cost approach to measure battery impedance 'on-line' in a vehicle across a range of frequencies (1-2000 Hz). Impedance measurement has promise for improving battery management since it is a very effective non-invasive method of diagnosing the internal state of an electrochemical cell. It is useful for estimating temperature, ageing, state of charge (SOC) and for fault detection. The aim of this paper is firstly to explore the usefulness of impedance for estimating SOC, focusing on lithium-ion iron phosphate (LFP) and nickel manganese cobalt oxide (NMC) cells, and secondly to demonstrate the performance of a low cost impedance measurement system that uses an existing motor drive similar to that of an electric vehicle to excite the battery current. We find that measurements made with this system are accurate to within a few per cent of results from an expensive, bulky commercial system. For SOC estimation in NMC cells, the charge transfer resistance and SEI layer resistance vary significantly with SOC. In LFP cells the parameter variation is much less obvious, although the double layer capacitance of the full pack may be a useful indicator of SOC.
Howey DA, Mitcheson PD, Yufit V, et al., 2014, Online measurement of battery impedance using motor controller excitation, IEEE Transactions on Vehicular Technology, Vol: 63, Pages: 2557-2566, ISSN: 0018-9545
This paper presents a fast cost-effective technique for the measurement of battery impedance online in an application such as an electric or hybrid vehicle. Impedance measurements on lithium-ion batteries between 1 Hz and 2 kHz give information about the electrochemical reactions within a cell, which relates to the state of charge (SOC), internal temperature, and state of health (SOH). We concentrate on the development of a measurement system for impedance that, for the first time, uses an excitation current generated by a motor controller. Using simple electronics to amplify and filter the voltage and current, we demonstrate accurate impedance measurements obtained with both multisine and noise excitation signals, achieving RMS magnitude measurement uncertainties between 1.9% and 5.8%, in comparison to a high-accuracy laboratory impedance analyzer. Achieving this requires calibration of the measurement circuits, including measurement of the inductance of the current sense resistor. A statistical correlation approach is used to extract the impedance information from the measured voltage and current signals in the presence of noise, allowing a wide range of excitation signals to be used. Finally, we also discuss the implementation challenges of an SOC estimation system based on impedance.
Carvalho NB, Georgiadis A, Costanzo A, et al., 2014, Wireless Power Transmission: R&D Activities Within Europe, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, Vol: 62, Pages: 1031-1045, ISSN: 0018-9480
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- Citations: 117
Merlin MMC, Green TC, Mitcheson PD, et al., 2014, The Alternate Arm Converter: A New Hybrid Multilevel Converter With DC-Fault Blocking Capability, IEEE Transactions on Power Delivery, Vol: 29, Pages: 310-317, ISSN: 0885-8977
This paper explains the working principles, supported by simulation results, of a new converter topology intended for HVDC applications, called the alternate arm converter (AAC). It is a hybrid between the modular multilevel converter, because of the presence of H-bridge cells, and the two-level converter, in the form of director switches in each arm. This converter is able to generate a multilevel ac voltage and since its stacks of cells consist of H-bridge cells instead of half-bridge cells, they are able to generate higher ac voltage than the dc terminal voltage. This allows the AAC to operate at an optimal point, called the “sweet spot,” where the ac and dc energy flows equal. The director switches in the AAC are responsible for alternating the conduction period of each arm, leading to a significant reduction in the number of cells in the stacks. Furthermore, the AAC can keep control of the current in the phase reactor even in case of a dc-side fault and support the ac grid, through a STATCOM mode. Simulation results and loss calculations are presented in this paper in order to support the claimed features of the AAC.
Lawson J, Pinuela M, Yates DC, et al., 2014, Long range inductive power transfer system, Journal of Physics : Conference Series, Vol: 476, Pages: 1-6, ISSN: 1742-6588
We report upon a recently developed long range inductive power transfer system (IPT) designed to power remote sensors with mW level power consumption at distances up to 7 m. In this paper an inductive link is established between a large planar (1 × 1 m) transmit coil (Tx) and a small planer (170 × 170 mm) receiver coil (Rx), demonstrating the viability of highly asymmetrical coil configurations that real-world applications such as sensor networks impose. High Q factor Tx and Rx coils required for viable power transfer efficiencies over such distances are measured using a resonant method. The applicability of the Class-E amplifier in very low magnetic coupling scenarios and at the high frequencies of operation required for high Q operation is demonstrated by its usage as the Tx coil driver.
Nunna K, Toh TT, Mitcheson PD, et al., 2014, Nonlinear observer and controller design for sensorless operation of a continuously rotating energy harvester, 19th World Congress of the International-Federation-of-Automatic-Control (IFAC), Publisher: ELSEVIER SCIENCE BV, Pages: 55-60, ISSN: 2405-8963
Kiziroglou ME, Wright SW, Toh TT, et al., 2014, Design and Fabrication of Heat Storage Thermoelectric Harvesting Devices, Industrial Electronics, IEEE Transactions on, Vol: 61, Pages: 302-309, ISSN: 0278-0046
Kwan CH, Lawson J, Yates DC, et al., 2014, Position-insensitive long range inductive power transfer, 14th International Conference on Micro- and Nano-Technology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
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- Citations: 4
Elliott ADT, Mitcheson PD, 2014, Piezoelectric energy harvester interface with real-time MPPT, 14th International Conference on Micro- and Nano-Technology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
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- Citations: 4
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
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- Citations: 5
Toh TT, Wright SW, Kiziroglou ME, et 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
Toh TT, Wright SW, Kiziroglou ME, et al., 2014, Inductive energy harvesting from variable frequency and amplitude aircraft power lines, ISSN: 1742-6596
Merlin MMC, Judge PD, Green TC, et al., 2014, Alternate Arm Converter Operation of the Modular Multilevel Converter, IEEE Energy Conversion Congress and Exposition (ECCE), Publisher: IEEE, Pages: 1924-1930, ISSN: 2329-3721
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- Citations: 14
Kkelis G, Lawson J, Yates DC, et al., 2014, Integration of a Class-E Low dv/dt Rectifer in a Wireless Power Transfer System, IEEE Wireless Power Transfer Conference (WPTC), Publisher: IEEE, Pages: 68-71
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- Citations: 3
Yeatman E, Mitcheson P, 2014, Energy Harvesting and Power Delivery, Body Sensor Networks, Publisher: Springer London, Pages: 237-272, ISBN: 9781447163732
Merlin MMC, Green TC, Mitcheson PD, et al., 2014, Cell capacitor sizing in modular multilevel converters and hybrid topologies, Pages: 1-10
Toh TT, Wright SW, Kiziroglou ME, et al., 2014, Inductive Energy Harvesting for Rotating Sensor Platforms, ISSN: 1742-6596
Halvorsen E, Le CP, Mitcheson PD, et al., 2013, Architecture-independent power bound for vibration energy harvesters, Journal of Physics: Conference Series, Vol: 476, ISSN: 1742-6588
The maximum output power of energy harvesters driven by harmonic vibrations is well known for a range of specific harvester architectures. An architecture-independent bound based on the mechanical input-power also exists and gives a strict limit on achievable power with one mechanical degree of freedom, but is a least upper bound only for lossless devices. We report a new theoretical bound on the output power of vibration energy harvesters that includes parasitic, linear mechanical damping while still being architecture independent. This bound greatly improves the previous bound at moderate force amplitudes and is compared to the performance of established harvester architectures which are shown to agree with it in limiting cases. The bound is a hard limit on achievable power with one mechanical degree of freedom and can not be circumvented by transducer or power-electronic-interface design.
Nunna K, Toh TT, Mitcheson PD, et al., 2013, Sensorless Estimation and Nonlinear Control of a Rotational Energy Harvester, The 13th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2013)
Borowiec M, Litak G, Rysak A, et al., 2013, Dynamic Response of a Pendulum-Driven Energy Harvester in the Presence of Noise, The 13th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2013)
Kiziroglou ME, Elefsiniotis A, Wright SW, et 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.
Elliott ADT, Dicken J, Miller LM, et al., 2013, Scheme for improved integration and lifetime for piezoelectric energy harvesters, IEEE Sensors, Pages: 1-4
The power output of piezo harvesters can be significantly increased by using charge modification techniques such as piezoelectric pre-biasing or synchronous switched harvesting, but in order to achieve a significant power gain high Q electrical resonant circuits must be used. For integrated systems with a significant size constraint, or in systems using on-chip inductors, achieving high Q can be difficult. Here we present an improved interface circuit which performs better than all previously presented techniques, especially in cases where the Q-factor of the resonant circuit is low. This has the added advantage of extending the useful life of the harvester because repeated cycling reduces the quality of the piezoelectric film, increasing the series resistance and lowering the electrical Q and the performance. Maximum power extraction by this new circuit is also less sensitive to the supply rail voltage than previously presented implementations, which reduces control power overhead.
Pinuela M, Mitcheson PD, Lucyszyn S, 2013, Ambient RF energy harvesting in urban and semi-urban environments, Transactions on Microwave Theory and Techniques, Vol: 61, Pages: 2715-2726, ISSN: 0018-9480
Pinuela M, Yates DC, Lucyszyn S, et al., 2013, Maximizing DC-to-Load Efficiency for Inductive Power Transfer, IEEE Transactions on Power Electronics, Vol: 28, Pages: 2437-2447, ISSN: 0885-8993
Inductive Power Transfer (IPT) systems for transmitting tens to hundreds of watts have been reported for almost a decade. Most of the work has concentrated on the optimization of the link efficiency and have not taken into account the efficiency of the driver. Class-E amplifiers have been identified as ideal drivers for IPT applications, but their power handling capabilityat tens of MHz has been a crucial limiting factor, since the load and inductor characteristics are set by the requirements of the resonant inductive system. The frequency limitation of the driver restricts the unloaded Q factor of the coils and thus the link efficiency. With a suitable driver, copper coilunloaded Q factors of over 1,000 can be achieved in the low MHz region, enabling a cost-effective high Q coil assembly. The system presented in this paper alleviates the use of heavy andexpensive field-shaping techniques by presenting an efficient IPT system capable of transmitting energy with a dc-to-load efficiency above 77% at 6 MHz across a distance of 30 cm. To the authorsknowledge this is the highest dc-to-load efficiency achieved for an IPT system without introducing restrictive coupling factor enhancement techniques.
Pinuela M, Yates DC, Mitcheson PD, et al., 2013, London RF Survey for Radiative Ambient RF Energy Harvesters and Efficient DC-load Inductive Power Transfer, 7th EurAAP European Conference on Antennas and Propagation (EUCAP 2013), Pages: 2839-2843
Elliott ADT, Dicken J, Miller LM, et al., 2013, Scheme for Improved Integration and Lifetime for Piezoelectric Energy Harvesters, 12th IEEE Sensors Conference, Publisher: IEEE, Pages: 1920-1923, ISSN: 1930-0395
Judge PD, Merlin MMC, Mitcheson PD, et al., 2013, Power Loss and Thermal Characterization of IGBT Modules in the Alternate Arm Converter, IEEE Energy Conversion Congress and Exposition (ECCE), Publisher: IEEE, Pages: 1731-1737, ISSN: 2329-3721
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- Citations: 11
Elefsiniotis A, Kiziroglou ME, Wright SW, et al., 2013, Performance evaluation of a thermoelectric energy harvesting device using various phase change materials, ISSN: 1742-6596
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