191 results found
Arteaga JM, Sanchez J, Elsakloul F, et al., 2023, High frequency inductive power transfer through soil for agricultural applications, IEEE Transactions on Power Electronics, Vol: 38, Pages: 13415-13429, ISSN: 0885-8993
This paper presents 13.56 MHz inductive powertransfer (IPT) through soil for sensors in agricultural ap-plications. Two IPT system designs and their prototypes are presented. The first was designed for gathering data and observing the relationship between the performance of the coil driving circuits in response to water content, salinity, organic matter and compaction of the soil. The second prototype was designed as an application demonstrator, featuring IPT to an in-house sensor node enclosure buried 200 mm under the surface of an agricultural field. The results highlight that from the parameters studied, the combination of high salinity and high water content significantly increases the losses of the IPT system.The experiments demonstrate an over 40% rise in the losses from dc source to dc load after a 16% increase in soil water content and high salinity. In the technology demonstrator we mounted an IPT transmitter on a drone to wirelessly power an in-house bank of supercapacitors in the buried sensor-node enclosure. A peak power transfer of 30 W received at over 40% efficiency was achieved from a 22 V power supply on the drone to the energy storage under the ground. The coil separation in these experiments was 250 mm of which 200 mm correspond to the layer of soil. The coupling factor in all the experiments was lower than 5%. This system was trialled in the field for forty days andwireless power was performed five times throughout.
Pucci N, Papavassiliou C, Mitcheson PD, 2023, Synchronous operation of high frequency inductive power transfer systems through injection locking, IEEE Transactions on Power Electronics, Vol: 38, Pages: 11984-11994, ISSN: 0885-8993
High frequency inductive power transfer systems can be designed for operation with high tolerance to misalignment and large air-gaps, making it possible to operate in highly dynamic environments. Most examples in the literature use a single active transmitter and a single passive receiver (active-passive approach). Such systems are limited to unidirectional power flow and are susceptible to detuning of the transmitter due to changes of reflected reactance stemming from diode non-linearities. This also limits the range of coupling over which the system can be operated efficiently. Therefore there is significant potential for expanding the range of applications of inductive power transfer systems by moving to an active-active configuration. This will enable bidirectional power flow, power routing through several nodes and on-the-fly retuning to eliminate reflected reactances. One of the greatest challenges in achieving an active secondary in an IPT system is obtaining a stable frequency and phase reference for the synchronous rectifier/transceiver with respect to the transmitter coil current and hence magnetic field. Various methods for synchronisation have been proposed in the literature, but they either require a separate, out of band communication link, or are difficult to scale to MHz operation. This paper describes an alternative to the existing solutions, using an injection locked oscillator to provide optimal phase tracking. A series of candidate feedback configurations are also proposed to provide high system resilience. In this work the basic principles of injection locking are described as applied to synchronous IPT transceivers and experimental results are presented demonstrating its application to a bidirectional back-to-back Class-EF configuration operating at 13.56 MHz, with coupling factors ranging from 1.9 % to 8.4 % and power levels of up to 25 W.
Wagih M, Balocchi L, Benassi F, et al., 2023, Microwave-Enabled Wearables: Underpinning Technologies, Integration Platforms, and Next-Generation Roadmap, IEEE Journal of Microwaves, Vol: 3, Pages: 193-226
Nikiforidis I, Arteaga JM, Kwan CH, et al., 2022, Generalised multistage modelling and tuning algorithm for class EF and class Φ inverters to eliminate iterative retuning, IEEE Transactions on Power Electronics, Vol: 37, Pages: 12877-12900, ISSN: 0885-8993
The additional complexity of Class EF and Class Φ inverters compared to their Class E counterparts, combined with parasitic effects becoming more prevalent as frequency and power levels increase, results in poor accuracy from traditional design methods, and usually additional iterations of manual retuning are required. In this work we propose an approach to simulating and tuning Class EF/Φ inverters, with various levels of accuracy depending on the level of knowledge of the system parasitics. Our method is comprised of a combination of analytic and numerical solving methods thus providing both insight on the progression of the algorithm and computational robustness. The aim of our algorithm formulation is to enable solutions to be found in an automated and fast way. The novelty in our work lies in the design method's concurrent capability to provide a generalised set of design inputs (e.g. DC to AC current gain, arbitrary drain voltage slope at turn on, Φ- branch resonance, etc.), inclusion of board and device non-linear parasitics, and the ability to design within the set of preferred component values. An example is shown for the design of a 50 W, 13.56 MHz inverter where the experimental setup approaches the theoretical efficiency of 97%. The algorithm changes the values of the components over 5% to 50% and improves the simulated waveform accuracy by 2 to 12 times compared to the design method based on first order approximations.
Arteaga JM, Mitcheson PD, Yeatman EM, 2022, Development of a fast-charging platform for buried sensors using high frequency IPT for agricultural applications, 2022 IEEE Applied Power Electronics Conference and Exposition (APEC), Publisher: IEEE, Pages: 1116-1121
This paper describes the methodology and experimental results for wireless power delivery to a soil-sensors power and data distribution unit from an unmanned aerial vehicle (UAV), using a high frequency inductive power transfer (HF-IPT) link. The configuration features, at the transmit side, a lightweight single-turn air-core coil driven by a 13.56 MHz Class EF inverter mounted on a Matrice 100 drone by DJI, and at the receive side, a two-turn PCB coil with a voltage-tipler Class D rectifier, an off-the-shelf 42 V battery charger and a supercapacitors module for energy storage. The experiments were conducted with a coil-to-coil gap of 250 mm, which corresponds to a coupling factor lower than 5%. In the experiments, a 10 F, 42 V supercapacitors module was charged in eleven minutes with an energy efficiency of 34% from the 80 V DC source that feeds the inverter on the drone to the supercapacitor-based energy storage unit in the sensor module. At higher power (50 W) the HF-IPT system was able to achieve a 68% DC-DC efficiency with a coupling factor of 3.5%. The work reported in this paper is part of a multiple-discipline project which looks to enable the optimal usage of water in agriculture with broader sensing techniques and more frequent sensing cycles.
Kampitsis G, Batzelis E, Mitcheson PD, et al., 2022, A clamping circuit based voltage measurement system for high frequency flying capacitor multilevel inverters, IEEE Transactions on Power Electronics, Vol: 37, Pages: 1-1, ISSN: 0885-8993
In an era where high-frequency flying capacitor (FC) multilevel inverters (MLI) are increasingly gaining attention in energy conversion systems that push the boundaries of power density, the need for a compact, fast, and accurate FC voltage monitoring is also increasing. In this paper we designed and developed a new FC measurement system, based on precise sampling of the inverter switching node voltage, through a bidirectional clamping circuit. The deviation of FC voltages from their nominal values are extracted by solving a set of linear equations. With a single sensor per phase and no isolation requirements, as opposed to dozens of sensors in traditional FC monitoring, our approach results in significantly lower cost, complexity, and circuit-size. Detailed device-level simulations in LTspice and system-scale simulations in Matlab, validate the accuracy and speed of the proposed measurement system and the balancing strategy in steady state, abrupt load change and imbalance conditions. Experiments carried out in a 3-phase Gallium-Nitride 5-level inverter prototype, reveal a gain in precision and bandwidth that is more than 30 times that of conventional methods, at a fraction of their cost and footprint. The recorded performance renders the developed sensor an ideal solution for fast MLIs based on wide-bandgap technology
Sanchez J, Arteaga JM, Pucci N, et al., 2022, Misalignment Parameterization of a 13.56 MHz Inductive Power Transfer System for in-situ Soil Sensing, Pages: 278-281
This paper discusses the measurement and characterization of the coil-to-coil misalignment in a 13.56 MHz inductive power transfer (IPT) system using variables that are either measurable on the wireless power transmitter alone (inverter current) or in conjunction with the receiver's Bluetooth module (rectifier voltage). A two- axis gantry transported the receiver on a plane 22 cm below the transmitter to perform these tests. The results from these tests demonstrate that the lateral coil-to-coil misalignment of this IPT system can be parameterized over the range of 0 to 30 cm with an average error of less than 2 cm. At peak alignment, this error decreases power transmission efficiency by less than 0.2%.
Aujla-Jones A, Arteaga JM, Gawith J, et al., 2022, A Measurement of the Power Dissipated due to the Mutual Flux Linking Two Loosely Coupled Coils, IEEE Workshop on Wide Bandgap Power Devices and Applications in Europe (WiPDA Europe), Publisher: IEEE
Pucci N, Arteaga JM, Mitcheson PD, 2022, Dynamic Receiver Characterisation in HF-IPT Systems, Wireless Power Week (WPW), Publisher: IEEE, Pages: 308-312
Sanchez J, Arteaga JM, Zeisiger C, et al., 2022, Integration of a High Frequency Inductive Power Transfer System to Energize Agricultural Sensors Through Soil, Wireless Power Week (WPW), Publisher: IEEE, Pages: 366-371
Pucci N, Arteaga JM, Kwan CH, et al., 2021, A 13.56 MHz bidirectional IPT system with wirelessly synchronised transceivers for ultra-low coupling operation, 2021 IEEE Energy Conversion Congress and Exposition (ECCE), Publisher: IEEE, Pages: 5781-5787
This paper presents a high-frequency inductive power transfer (HF-IPT) system with bidirectional capability employing a new wireless synchronisation method. Synchronisation is achieved by transmitting a reference ultra high frequency tone (433.92 MHz) that is stepped down to 13.56 MHz in each transceiver. This allows the operating frequency to be locked across the two sides of the system. Afterwards, a phase search is performed looking for maximum power throughput, determining the phase at the point of resonance (i.e., no reflected reactances). The experimental implementation is achieved with two back-to-back Class EF coil-drivers driven by independent synchronisation circuits. In the experimental setup a constant input voltage is set for each of the two coil-drivers by implementing a source-sink configuration, emulating a bidirectional DC-DC conversion stage at each side. Experimental results show successful transceiver synchronisation, and 4 W were transferred from one end to the other and conversely at an ultra-low coupling of 1.6%. This proves that the combination of the load-independent Class EF transceivers and the synchronisation technique introduced herein is suitable for applications that require large tolerance to misalignment and air gaps larger than one coil diameter, such as in micro e-mobility.
Pucci N, Arteaga JM, Kwan C, et al., 2021, Induced voltage estimation from class EF switching harmonics in HF-IPT systems, IEEE Transactions on Power Electronics, Vol: 37, Pages: 4903-4916, ISSN: 0885-8993
One of the advantages of high-frequency inductive power transfer systems is the high tolerance to misalignment and large air-gaps. However, the inherently large magnetic field volumes can lead to coupling of additional foreign objects with the primary, causing possible detuning of the system and heating of the objects. These foreign objects and the conditions of the local environment can load the transmitter, which changes the induced voltage on the primary side. Unfortunately, the induced voltage is not directly measurable in an operating transmitter and the most straightforward way of calculating this variable, through a measurement of primary coil current and voltage, can cause a significant decrease in quality factor which reduces system performance. An integrated solution capable of estimating the induced voltage through other less invasive measurements in the primary is needed to ensure safety of operation through foreign object detection. Knowledge of the induced voltage can also be used to correct tuning mismatches where both sides of the link are active (i.e., in synchronous rectification and bidirectional systems). In this article, multiple candidate variables for estimating the induced voltage are assessed based on factors such as measurement practicality and estimation accuracy. It is demonstrated for the first time that a solution which is based on the measurement of only two variables, the amplitude of the fundamental frequency of the switching waveform and input current, can achieve state-of-the-art induced voltage estimation accuracy. These two variables, which can be obtained using simple cost-effective analogue circuitry, are used in a Gaussian process to generate a regression model. This is used to estimate induced voltages at any angle in an approximate magnitude range of 0–20 V with a normalized root-mean-square error of 1% for the real part and 1.5% for the imaginary part. This corresponds to detecting a plastic container with 1 kg of sal
Arteaga Saenz J, Pucci N, Lan L, et al., 2021, Load characterisation in high frequency IPT systems using Class EF switching waveforms, IEEE Transactions on Power Electronics, Vol: 36, Pages: 11036-11044, ISSN: 0885-8993
This paper introduces a technique to calculate the induced voltage generated by coupled-receivers and foreign-objects on the transmit-coil in real-time. Changes in the position or electrical quantities of the receivers, and foreign-objects, alter the induced voltage on the transmit-coil, and with it the trajectory of the switching-waveforms of the inverter driving the transmit-coil. From the shape of these waveforms, information on the phase and amplitude of the induced voltage can be extracted, thus enabling the induced voltage on the primary to be estimated with a single, easy to access, voltage measurement, which is easier than estimating the induced voltage from measurements of coil current and total coil-voltage. We used a support-vector-machine(SVM) to perform regression analysis on the drain-voltage data. The experimental setup uses a 100W, 13.56MHz Class-EF inverter, and the model was generated from a large number of samples of the drain-voltage waveforms operating at different known loads. These were generated from our in house HF-IPT test-load, which uses a Class-EF synchronous rectifier. The results allow the induced voltage on the transmit-coil to be estimated in real time from the drain-voltage waveform alone, with a normalised root-mean-square error of 1.1% for the real part~(reflected resistance) and 1.2% for the imaginary part~(reflected reactance).
Arteaga JM, O'Keefe J, Boyle DE, et al., 2021, Interrogation and charging of embedded sensors by autonomous vehicles, 2021 21st International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers), Publisher: IEEE, Pages: 296-299
This paper presents a concept and experimental results for end-to-end energy-autonomous sensor systems using unmanned aerial vehicles (drones) as agents for power delivery to and data gathering from sensing devices. Such systems are particularly useful for delay tolerant monitoring scenarios in which the sensing devices are deployed in remote or harsh conditions, often with sparse connectivity, long life and high reliability requirements. Results presented include miniaturisation of wireless charging hardware for drones of low payload capacity, methods for navigation to and alignment with sensors for efficient power transfer, and some data transfer aspects.
Arteaga JM, Kwan CH, Nikiforidis I, et al., 2021, Design of a one-to-four isolated DC-DC converter using a 13.56 MHz resonant air-core transformer, 2021 IEEE Applied Power Electronics Conference and Exposition (APEC), Publisher: IEEE, Pages: 2580-2585
This paper showcases the design and development of a DC-DC converter with one input and four outputs using a high frequency resonant air-core transformer. The transmitter to receivers air-gap is 25 mm. Practical tuning equations were derived for multiple receivers which allow the converter to be optimised for overall efficiency and unity power factor at the transmit coil (i.e. zero reflected reactance). Experiments were conducted using two receive coil structures, one with four equally shaped adjacent coils in a single PCB, and the other with four differently-shaped coils featuring overlapping traces to maximise the coupling factor with the transmitter and minimise the coupling factor between the receivers. The two structures were tested and compared using the same transmitter, driven by a single-ended 13.56 MHz Class EF inverter. Single-ended Class D rectifiers were implemented at the receive side. Experiments were performed, first with equal AC test loads, and afterwards with the addition of the rectifiers and buck converters to regulate each of the four output voltages to 15 V independently. The results of the experiments implementing adjacent coils demonstrate that equal distribution of power can be achieved by modifying the tuning capacitances at the receivers with the AC loads; however, when the voltage-regulating buck converters were introduced at each output, it was only with the coil structure with overlapping traces that the required power of 10 W at each output was achieved.
Kwan CH, Arteaga JM, Pucci N, et al., 2021, A 110 W e-scooter wireless charger operating at 6.78 MHz with ferrite shielding, IEEE Wireless Power Week (WPW) / IEEE MTT-S Wireless Power Transfer Conference (WPTC) / IEEE PELS Workshop on Emerging Technologies - Wireless Power (WoW), Publisher: IEEE
This paper reports on the design, construction and integration of a wireless inductive charging solution for an electric scooter, operating at a frequency of 6.78MHz and providing an output power of 110 W. With the use of a push-pull Class EF inverter at the transmit end, as well as ferrite shielding and a voltage-doubler full-wave Class D rectifier at the receive end, this system achieved a DC-DC IPT efficiency of 69%-75% and exhibited good tolerance to misalignment at full charging power.
Pucci N, Arteaga JM, Mitcheson PD, 2021, Design and development of a test rig for 13.56 MHz IPT systems with synchronous rectification and bidirectional capability, IEEE Wireless Power Week (WPW) / IEEE MTT-S Wireless Power Transfer Conference (WPTC) / IEEE PELS Workshop on Emerging Technologies - Wireless Power (WoW), Publisher: IEEE, Pages: 1-5
This paper presents the development of a test rig for bidirectional 13.56 MHz wireless power using identical back-to-back Class EF converters. Theoretical principles of bi-directional wireless power are described and an operating chart representing the range of admissible complex voltages induced on the active transmit side is introduced. The implementation is achieved by driving the gate signals of two Class EF coil-drivers from a signal generator, allowing the relative phase of the currents in each coil to be controlled. The rig sets a constant input voltage for each of the two coil-drivers by implementing a source-sink configuration, emulating a bidirectional DC-DC conversion stage at each side. This setup can also be used to test for tuning mismatches and different loading conditions in the back-to-back Class EF configuration. Experimental results include bidirectional wireless power transmission of 20 W across a 13.56 MHz link with 6.56% coupling. The combination of low coupling factors and moderate power levels enables new classes of applications that require large air gaps and tolerance to misalignment such as in micro e-mobility. High efficiency can be maintained despite changes in coupling factors and load since active rectification ensures operation at the resonant point in both tanks.
Kwan C, Arteaga Saenz J, Aldhaher S, et al., 2020, A 600W 6.78MHz wireless charger for an electric scooter, IEEE PELS WoW 2020, Publisher: IEEE, Pages: 278-282
This paper presents a 600 W electric scooter wireless charging solution operating at a frequency of 6.78 MHz. At the transmitter end, a load-independent Class EF push-pull(differential) inverter with GaN transistors was used to drive a 33 cm square-shaped copper pipe coil. A full-wave voltage-triplerClass D rectifier with silicon Schottky diodes was connected to a24 cm-by-26 cm trapezoidal receiver coil (also made of copperpipe) mounted underneath the steel frame of the scooter. In order to reduce the eddy current and magnetic losses in the steel chassis, parts of the electric scooter frame were shielded with copper tape. With the battery recharging in situ at 600 W,the IPT system achieved a DC-to-DC efficiency of 84 %.
Kim J, Clerckx B, Mitcheson PD, 2020, Signal and system design for wireless power transfer: prototype, experiment and validation, IEEE Transactions on Wireless Communications, Vol: 19, Pages: 7453-7469, ISSN: 1536-1276
A new line of research on communications and signals design for Wireless Power Transfer (WPT) has recently emerged in the communication literature. Promising signal strategies to maximize the power transfer efficiency of WPT rely on (energy) beamforming, waveform, modulation and transmit diversity, and a combination thereof. To a great extent, the study of those strategies has so far been limited to theoretical performance analysis. In this paper, we study the real over-the-air performance of all the aforementioned signal strategies for WPT. To that end, we have designed, prototyped and experimented an innovative radiative WPT architecture based on Software-Defined Radio (SDR) that can operate in open-loop and closed-loop (with channel acquisition at the transmitter) modes. The prototype consists of three important blocks, namely the channel estimator, the signal generator, and the energy harvester. The experiments have been conducted in a variety of deployments, including frequency flat and frequency selective channels, under static and mobility conditions. Experiments highlight that a channel-adaptive WPT architecture based on joint beamforming and waveform design offers significant performance improvements in harvested DC power over conventional single-antenna/multi-antenna continuous wave systems. The experimental results fully validate the observations predicted from the theoretical signal designs and confirm the crucial and beneficial role played by the energy harvester nonlinearity.
Lan L, Kwan CH, Arteaga JM, et al., 2020, A 100W 6.78MHz inductive power transfer system for drones, 2020 14th European Conference on Antennas and Propagation (EuCAP), Publisher: IEEE, Pages: 1-4
This paper reports on the design and development of a wireless charging solution for a DJI Matrice 100 quadcopter drone. The system is based on a high frequency inductive power transfer system built with lightweight copper pipe air-core coils at both ends and lightweight electronics at the receive side. The developed system is capable of delivering power to the drone at the same rate as the original wired charger (100W) when landed at any position on the charging pad, regardless of the lateral misalignment or angular orientation. The charging pad is circular with a one-metre diameter, therefore allowing for a lateral misalignment of up to 25cm. The system has an average mains-to-battery efficiency of 70% and enables the drone missions to be completely autonomous as it eliminates the need for human interference for battery recharging or swapping.
Arteaga Saenz JM, Lan L, Kwan CH, et al., 2020, Characterisation of high frequency inductive power transfer receivers using pattern recognition on the transmit side waveforms, IEEE Applied Power Electronics Conference and Exposition (APEC), Publisher: IEEE, Pages: 825-831, ISSN: 1048-2334
This paper demonstrates the characterisation of inductively coupled receivers for high frequency inductive power transfer (HF-IPT) systems using pattern recognition on the inverter waveforms at the transmit side. The impedance reflected by the candidate receivers to the transmit coil was estimated using a model programmed to associate the experimental drain-voltage waveforms of the inverter when it drives a receiver under test to those when driving known loads. The necessity of employing this technique is due to the difficulty of accurately measuring current and voltage across the coil given the parasitic effects of probing and the precise skewing required to measure an impedance, especially at high Q-factor. The proposed technique is convenient for characterising and comparing the impedance reflected by candidate receivers for a particular application where there is a choice to be made with respect to the rectifier topologies and semiconductor technologies. Experimental results, using a 13.56 MHz 100 W inductive power transfer system, were obtained for a full-wave Class D rectifier using silicon (Si) and silicon carbide (SiC) Schottky diodes, and two Class E rectifiers using SiC diodes.
Nikiforidis I, Arteaga JM, Kwan CH, et al., 2020, Design and modelling of class EF inverters for wireless power transfer applications, 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Power MEMS), Publisher: IEEE, Pages: 1-4
Class EF inverters have been widely used recently as primary coil drivers for wireless power transfer applications since they achieve constant output current across a range of link coupling factor values. As the operating frequency that the inductive link is tuned at increases the traditional circuit design techniques that are based on first order calculations fail to represent the inverter behaviour accurately. In this paper, we present a novel method of modelling Class EF inverters that is based on state space representation of the circuit and thus providing the highest accuracy possible. Our method consists of a combination of analytical and numerical calculations in such manner that any parasitic component of the circuit, such as the nonlinear output capacitance of a power switch, can be included in the tuning process.
Pucci N, Kwan CH, Yates DC, et al., 2020, Multi-megahertz IPT systems for biomedical devices applications, 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Power MEMS), Publisher: IEEE, Pages: 1-7
This paper investigates the main design constraints for the optimisation of an inductive power transfer (IPT) link for recharging implantable medical devices , and presents the potential advantages of operating in the multi-MHz range for such applications. The design proposed in this paper offers a fast charging solution, allowing patients to recharge their active medical implants every 4-5 years for 40% of its battery capability. The main challenge consists of obtaining good coupling and effective Q factor of the receiver coil, while minimizing the overall increase in size of the medical implant. Analysis obtained through electromagnetic simulations with CST Studio Suite for a 13.56 MHz, 1 W system suggests that it is possible to achieve a relatively high theoretical link efficiency of 66%, while keeping surface temperature increases and specific absorption rate (SAR) within the limits established in EN 45502  and ICNIRP 1998 . The experimental results show two feasible systems with different separation distances between the device's metallic case and the receiver coil, achieving transfer efficiencies  of 41% and 53% for separations of 1 mm and 7 mm, respectively.
Lan L, Arteaga JM, Yates DC, et al., 2020, A reflected impedance estimation technique for inductive power transfer, IEEE MTT-S Wireless Power Transfer Conference (WPTC) / IEEE PELS Workshop on Emerging Technologies - Wireless Power (WoW) / Wireless Power Week Conference, Publisher: IEEE, Pages: 45-48
This paper proposes a technique to estimate the equivalent reflected impedance on the transmit side of an inductive power transfer (IPT) system, produced by an inductively coupled load. This technique consists of analysing changes in the drain voltage waveform of the switching devices to estimate the reflected impedance, and hence not require feedback information from the receive side or the coupling between the coils. The correlation between the drain voltage waveform and the reflected impedance is done by training a model with machine learning techniques. The proposed impedance estimation method is demonstrated using circuit simulations and is verified experimentally, with an IPT transmitter driven by a load independent Class EF inverter operating at 13.56 MHz. The IPT receiver consists of an ac-load which allows changes in the residual reactance. The model trained from experimental data is capable of estimating the equivalent reflected impedance with an accuracy (coefficient of determination) of 0.9899 for the real part and 0.9743 for the imaginary part.
Skountzos E, Arteaga JM, Hadjittofis E, et al., 2020, A 13.56 MHz inductive power transfer system operating with corroded coils, 2019 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer (WoW), Publisher: IEEE, Pages: 335-340
This paper describes experiments which investigate the effects resulting from corrosion of air-core coils for high frequency inductive power transfer (HF-IPT). A group of coils were treated by exposing them to corrosive conditions for thirty days. Afterwards, the coils were measured with an impedance analyser and the coil with the lowest Q-factor was selected for further experiments. The treated coil was tested at the transmit side of a HF-IPT system, where the system DC-to-DC efficiency was measured and compared against an equivalent system using an untreated transmit coil. The total losses measured increased when the system was operating with the treated coil across a broad loading range, and thermal images were used to establish the additional losses on the treated coil. Analysis of the treated coil identified widespread damage to the surface of the coil. However, it was specific aggressive corrosion only found locally which was able to significantly reduce the Q-factor of the treated coil by 20%.
Pucci N, Kwan CH, Yates DC, et al., 2020, Effect of fields generated through wireless power transfer on implantable biomedical devices, 2019 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer (WoW), Publisher: IEEE, Pages: 1-5
This paper assesses the safety of pacemakers when exposed to the electromagnetic (EM) field generated by high frequency inductive power transfer (HF-IPT) systems. It includes both simulation and experimental results, showing temperature variations to ensure conformity with the EN standards, changes in detected lead impedance and determining whether EM field strength can affect the operating mode of the device. This is the first time the interaction between 6.78MHz, 100W HF-IPT systems and pacemaker devices was tested up to distances of 5 cm to 10 cm, Temporary decrease of detected lead's impedance and interruption of communications are the most relevant effects recorded through in-vitro tests. No permanent alteration of the device's operation was recorded, indicating good early stage evidence of safety for pacemaker users in proximity of this new emerging technology.
Lan L, Polonelli T, Qin Y, et al., 2020, An Induction-Based Localisation Technique for Wirelessly Charged Drones, IEEE PELS Workshop on Emerging Technologies - Wireless Power Transfer (WoW) / IEEE Wireless Power Week (WPW) / IEEE MTT-S Wireless Power Transfer Conference (WPTC), Publisher: IEEE, Pages: 275-277
Calderon-Lopez G, Todd R, Forsyth AJ, et al., 2020, Towards Lightweight Magnetic Components for Converters with Wide-bandgap Devices, IEEE 9th International Power Electronics and Motion Control Conference (IPEMC-ECCE Asia), Publisher: IEEE, Pages: 3149-3155
Visser HJ, Mitcheson PD, Lan L, et al., 2019, Conference Report <i>IEEE Wireless Power Week 2019</i>, IEEE MICROWAVE MAGAZINE, Vol: 20, Pages: 111-113, ISSN: 1527-3342
Arteaga Saenz J, Aldhaher S, Kkelis G, et al., 2019, Dynamic capabilities of multi-MHz inductive power transfer systems demonstrated with batteryless drones, IEEE Transactions on Power Electronics, Vol: 34, Pages: 5093-5104, ISSN: 0885-8993
This paper presents the design of a multi-MHz inductive power transfer (IPT) system showcasing lightweight and energy-efficient solutions for non-radiative wireless power transfer. A proof of concept is developed by powering a drone without a battery that can hover freely in proximity to an IPT transmitter. The most challenging aspect, addressed here for the first time, is the complete system level design to provide uninterrupted power-flow efficiently while allowing for variable power demand and highly variable coupling factor. The proposed solution includes the design of lightweight air-core coils that can achieve sufficient coupling without degrading the aerodynamics of the drone, and designing newly-developed resonant power converters at both ends of the system. At the transmittingend, a load-independent Class EF inverter, which can drive a transmitting-coil with constant current amplitude and achieves zero-voltage switching (ZVS) for the entire range of operation, was developed; and at the receiving-end, a hybrid Class E rectifier, which allows tuning for large changes in coupling and power demand, was used. For the demo, the range of motion of the drone was limited by a 7.5 cm nylon string tether, connected between the centre of the transmitting-coil and the bottom of the drone. The design of the IPT system, including all the power conversion stages and the IPT link, is explained in detail. The results on performance and specific practical considerations required for the physical implementation are provided. An average end-to-end efficiency of 60% was achieved for a coupling range of 23% to 5.8%. Relevant simulations concerning human exposure to electromagnetic fields are also included to assure that the demo is safe according to the relevant guidelines. This paper is accompanied by a video featuring the proposed IPT system.
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