Development of a Wireless Power Transfer System using Resonant Inductive Coupling

Access to power is a fundamental requirement for the effective functioning of any electrical/electronic circuit. The conduit of transfer of power can be either physical (wires, cables etc.) of non-physical (i.e. wireless). Wireless power transfer is a broad term used to describe any means used to transmit power to electricity dependent systems and devices. In this paper, a wireless power transfer system is developed to provide an alternative to using power cords for electrical/electronic devices. With this technology, challenges like damaged or tangled power cords, sparking hazards and the extensive use of plastic and copper used in cord production are resolved and also the need for batteries in non-mobile devices is eliminated. In this system, electromagnetic energy is transmitted from a power source (transmitter) to an electrical load (receiver) via resonant inductive coupling. The performance achieved is a good indication that power can still be transmitted over a medium range. In addition, possible ways of improving the efficiency of the system are discussed

Magnetic Resonance Wireless Power Transfer Systems Sensing and Applications

Magnetic Resonance (MR) Wireless Power Transfer (WPT) is a specific case for thewell known inductive coupling principle where energy is transmitted from a transmittingcoil to a receiving one without the need of any wires. This technology brings enhancedcapabilities and offers the possibility to create cutting edge wireless charging systems. Theobjective of this thesis is to understand and develop the elements needed to build a MR WPT system capable of charging multiple wearable devices placed over a large surface.The focus is put in current and voltage sensing at high frequency for system monitor-ing; power amplifier topology design to maintain good performance across a range of loadvalues; and the beamforming and energy hopping applications validation to deal withcharging area coverage and transmission distance issues. The results show how the pres-ence of a receiver can be detected from the current change measured at the transmitter, aswell as voltage measurements are used as redundant information for system failure detec-tion; a class E power amplifier has been successfully designed to operate with loads thatdiffer 1 order of magnitude from each other; beamforming and energy hopping simulationenvironments have been set, and experiments have shown a 50% improve in the receivedsignal strength with the use of beamforming, while the enrgy hopping phenomena hasbeen empirically demonstrated for up to four hops along a planar array of coils. A solidbasis has been set to allow further development of the aimed wireless charging surface

Midrange Magnetically-Coupled Resonant Circuit Wireless Power Transfer

Recent years have seen numerous efforts to make wireless power transfer (WPT) feasible for application in diverse fields, from low-power domestic applications and medical applications to high-power industrial applications and electrical vehicles (EVs). As a result, it has been found that WPT by means of non-radiative magnetically-coupled resonant circuits is an optimum method for mid-range applications where the separation of source and receiver is in the range of 1-2m.This thesis investigates various aspects of the design of magnetically-coupled resonant circuits for non-radiative WPT. Firstly, a basic four-coil network for a mid-range (1-2m gap) WPT system with a single power source and single resistive load was developed and simulated. The system was then constructed and experimental results were obtained for comparison with theoretical expectations. Methodologies were developed for empirical measurement of flux-coupling coefficients (k) among the coupled resonator coils and measurement of resonator parameters (inductance, capacitance, and equivalent-series resistance). Secondly, a structure called a universal resonator is proposed to permit design of WPT networks of arbitrary complexity with multiple power sources (transmitters) and multiple loads (receivers). An Excel simulation tool has been developed to analyze designs involving up to eight resonators. Designs with five resonators (including one power source and two loads) and six resonators (with two power sources and two loads) with separation of 1m between transmitting and receiving resonators have been analyzed, constructed, and subjected to experimental validation. The measured outputs numerical were found to be in good agreement with the predicted models. Conclusions and suggestions for future work are provided

Inductively Coupled CMOS Power Receiver For Embedded Microsensors

Inductively coupled power transfer can extend the lifetime of embedded microsensors that save costs, energy, and lives. To expand the microsensors' functionality, the transferred power needs to be maximized. Plus, the power receiver needs to handle wide coupling variations in real applications. Therefore, the objective of this research is to design a power receiver that outputs the highest power for the widest coupling range. This research proposes a switched resonant half-bridge power stage that adjusts both energy transfer frequency and duration so the output power is maximally high. A maximum power point (MPP) theory is also developed to predict the optimal settings of the power stage with 98.6% accuracy. Finally, this research addresses the system integration challenges such as synchronization and over-voltage protection. The fabricated self-synchronized prototype outputs up to 89% of the available power across 0.067%~7.9% coupling range. The output power (in percentage of available power) and coupling range are 1.3× and 13× higher than the comparable state of the arts.Ph.D

Arbitrary power distribution and efficiency optimization for dual-receiver inductive power transfer system with variable coupling

In dynamic wireless charging application for electric vehicles, multi-receiver inductive power transfer (IPT) systems hold enormous potential. However, the couplings and the charging rates are significantly different between vehicles and varies randomly, which causes the systems’ efficiency deviate from their optimal state. This paper presents an analytical model for solving the optimal control variables, which considers arbitrary loads and couplings. Based on the proposed model, with further considering coupling and load restriction, the feasible regulation trajectories of primary inverter and secondary active rectifier phases are derived. Besides, a maximum efficiency point tracking (MEPT) control strategy are designed for achieving selective power distribution and constant current output characteristics simultaneously. Finally, an IPT experiment with dual loads is designed and carried out. The experimental results show that the ideal power distribution can be maintained for each receiver under load voltage, demand current and coupling variations, furthermore, the efficiency of the proposed system can be improved by 3% to a maximum of 89.13% compared to the system without MEPT

Design of Power Receiving Units for 6.78MHz Wireless Power Transfer Systems

In the last decade, the wireless power transfer (WPT) technology has been a popular topic in power electronics research and increasingly adopted by consumers. The AirFuel WPT standard utilizes resonant coils to transfer energy at 6.78 MHz, introducing many benefits such as longer charging distance, multi-device charging, and high tolerance of the coil misalignment. However, variations in coil coupling due to the change in receiving coil positions alter the equivalent load reactance, degrading efficiency. In recent studies, active full-bridge rectifiers are employed on WPT receivers because of their superior efficiency, controllability, and ability to compensate for detuned WPT networks. In order to take advantage of those characteristics, the rectifier switching actions must be synchronized with the magnetic field. In the literature, existing solutions for synchronizing the active rectifier in WPT systems are mostly not reliable and bulky, which is not suitable for small receivers. Therefore, a frequency synchronous rectifier with compact on-board control is proposed in this thesis. The rectifier power stage is designed to deliver 40 W to the load while achieving full zero-voltage switching to minimize the loss. The inherent feedback from the power stage dynamics to the sensed signal is analyzed to design stable and robust synchronization control, even at a low power of 0.02 W. The control system is accomplished using commercial components, including a low-cost microcontroller, which eliminates the need for bulky control and external sensing hardware. This high power density design allows the receiver to be integrated into daily consumer electronics such as laptops and monitors. Finally, a wide-range and high v resolution control scheme of the rectifier input phase is proposed to enable the dynamic impedance matching capability, maintaining high system efficiency over wide loading conditions. In addition, to increase the WPT technology adoption to low-power consumer electronics, a small wireless receiver replacing conventional AA batteries is developed. This receiver can supply power to existing AA battery-powered devices while providing the benefit of WPT technologies to consumers

Double Resonant High-Frequency Converters for Wireless Power Transfer

This thesis describes novel techniques and developments in the design and implementation of a low power radio frequency (40kHz to 1MHz) wireless power transfer (WPT) system, with an application in the wireless charging of autonomous drones without physical connection to its on-board Battery Management System (BMS). The WPT system is developed around a matrix converter exploiting the benefits such as a small footprint (DC-link free), high efficiency and high power density. The overall WPT system topology discussed in this thesis is based on the current state-of-the-art found in literature, but enhancements are made through novel methods to further improve the converter’s stability, reduce control complexity and improve the wireless power efficiency. In this work, each part of the system is analysed and novel techniques are proposed to achieve improvements. The WPT system design methodology presented in this thesis commences with the use of a conventional full-bridge converter. For cost-efficiency and to improve the converters stability, a novel gate drive circuit is presented which provides self-generated negative bias such that a bipolar MOSFET drive can be driven without an additional voltage source or magnetic component. The switching control sequences for both a full-bridge and single phase to single phase matrix converter are analysed which show that the switching of a matrix converter can be considered to be the same as a full-bridge converter under certain conditions. A middleware is then presented that reduces the complexity of the control required for a matrix converter and enables control by a conventional full-bridge controller (i.e. linear controller or microcontroller). A novel technique that can maximise and maintain in real-time the WPT efficiency is presented using a maximum efficiency point tracking approach. A detailed study of potential issues that may affect the implementation of this novel approach are presented and new solutions are proposed. A novel wireless pseudo-synchronous sampling method is presented and implemented on a prototype system to realise the maximum efficiency point tracking approach. Finally, a new hybrid wireless phase-locked loop is presented and implemented to minimise the bandwidth requirements of the maximum efficiency point tracking approach. The performance and methods for implementation of the novel concepts introduced in this thesis are demonstrated through a number of prototypes that were built. These include a matrix converter and two full WPT systems with operating frequencies ranging from sub-megahertz to megahertz level. Moreover, the final prototype is applied to the charging of a quadcopter battery pack to successfully charge the pack wirelessly whilst actively balancing the cells. Hence, fast battery charging and cell balancing, which conventionally requires battery removal, can be achieved without re-balance the weight of the UAV

ELECTROMAGNETIC INDUCTION TECHNIQUE OF WIRELESS POWER TRANSFER FOR UNIVERSAL WIRELESS CHARGING DEVICE

Abstract: With the constant and increase growth in technological advancements, technical know-how and innovations, keeping up with the trends becomes the order of the day, most technological advancement aim at further improving our way of life and/or providing new and easier ways to solve a general problem, with so many examples to site, like the invention of smart home security systems, smart baby monitors, self-driven cars, digital voting systems etc, wireless power transfer seems to be at the very top of this list. The main objective of wireless power transfer is to eliminate damage of mobile phone USB port and make the transfer of power from sources to devices more convenient and seamless. Wireless charging of gadgets is one of the new emerging technologies in the world at the moment. The most common method used at the moment is wireless power transfer by inductive coupling. Wireless power transfer is one of the simplest and cheapest ways of charging as it eliminates the use of conventional copper cables and current carrying wires. The research methodology and principle of operation are devised for wireless power transfer through inductive coupling, and a feasible design is modeled accordingly. The inductive coupling technique is used since currently it’s the easiest method of wireless power transfer because of high efficiency and large amount of the energy transferred. In this project report, results of experiments done to check wireless power transfer will be discussed. Also, to further show its versatility and range of applications the power transferred will be used to charge small and medium devices with emphasis on mobile phones with the aid of additional circuitry; and also study the effect of placing hurdles between the transmitter and receiver so as to establish if it is an alternative in the medical industry for charging pace makers. Keywords: Electromagnetic Induction, Electromagnetic Hypothesis, Inductive Coupling, Wireless Power Transfer (WPT), Wireless Charger, Resonant Transformer, Contactless Feed System. Title: ELECTROMAGNETIC INDUCTION TECHNIQUE OF WIRELESS POWER TRANSFER FOR UNIVERSAL WIRELESS CHARGING DEVICE Author: Ogbodo Emmanuel Utochukwu, Ifeyinwa Faith Ogbodo, Onyenanu Chukwunonso Nnanyelum, Nwanonobi Benjamin Chibuzo International Journal of Recent Research in Electrical and Electronics Engineering (IJRREEE) ISSN 2349-7815 Vol. 10, Issue 3, July 2022 - September 2023 Page No: 10-21 Paper Publications Website: www.paperpublications.org Published Date: 18-September-2023 DOI: https://doi.org/10.5281/zenodo.8355586 Paper Download Link (Source) https://www.paperpublications.org/upload/book/ELECTROMAGNETIC%20INDUCTION%20TECHNIQUE-18092023-6.pdfInternational Journal of Recent Research in Electrical and Electronics Engineering (IJRREEE), ISSN 2349-7815, Paper Publications, Website: www.paperpublications.or

Past, Present and Future Trends of Non-Radiative Wireless Power Transfer

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Circuits and systems for inductive power transfer

Recently, the development of Wireless Power Transfer (WPT) systems has shown to be a key factor for improving the robustness, usability and autonomy of many mobile devices. The WPT link relaxes the trade-off between the battery size and the power availability, enabling highly innovative applications. This thesis aims to develop novel techniques to increase efficiency and operating distance of inductive power transfer systems. We addressed the design of the inductive link and various circuits used in the receiver. Moreover, we performed a careful system-level analysis, taking into account the design of different blocks and their interaction. The analysis is oriented towards the development of low power applications, such as Active Implantable Medical Device (AIMD) or Radio-Frequency Identification (RFID) systems. Three main approaches were considered to increase efficiency and operating distance: 1) The use of additional resonant coils, placed between the transmitter and the receiver. 2) The receiver coil impedance matching. 3) The design of high-efficiency rectifiers and dc-dc converters. The effect of the additional coils in the inductive link is usually studied without considering its influence on other parts of the WPT system. In this work, we theoretically analyzed and compared 2 and 3-coil links, showing the advantages of using the additional coil together with a matching network in the receiver. The effect of the additional coils in a closed-loop regulated system is also addressed, demonstrating that the feedback-loop design should consider the number of coils used in the link. Furthermore, the inclusion of one additional resonant coil in an actual half-duplex RFID system at 134:2 kHz is presented. The maximum efficiency point can be achieved by adjusting the receiver coil load impedance in order to reach its optimum value. In inductive powering, this optimum impedance is often achieved by adapting the input impedance of a dc-dc converter in the receiver. A matching network can also be used for the same purpose, as have been analyzed in previous works. In this thesis, we propose a joint design using both, matching network and dc-dc converters, highlighting the benefits of using the combined approach. A rectifier must be included in any WPT receiver. Usually, a dc-dc converter is included after the rectifier to adjust the output voltage or control the rectifier load impedance. The efficiency of both, rectifier and dc-dc converter, impacts not only the load power but also the receiver dissipation. In applications such as AIMDs, to get the most amount of power with low dissipation is crucial to full safety requirements. We present the design of an active rectifier and a switched capacitor dc-dc converter. In low-power applications, the power consumption of any auxiliary block used in the circuit may decrease the efficiency due to its quiescent consumption. Therefore, we have carefully designed these auxiliary blocks, such as operational transconductance amplifiers and voltage comparators. The main contributions of this thesis are: . Deduction of simplified equations to compare 2 and 3-coil links with an optimized Matching Network (MN). . Development of a 3-coil link half-duplex RFID 134.2 kHz system. . Analysis of the influence of the titanium case in the inductive link of implantable medical devices. . Development of a joint design ow which exploits the advantages of using both MNs and dc-dc converters in the receiver to achieve load impedance matching. . Analysis of closed-loop postregulated systems, highlighting the effects that the additional coils, receiver resonance (series or parallel), and type of driver (voltage or current) used in the transmitter, have in the feedback control loop. . Proposal of systematic analysis and design of charge recycling switches in step-up dc-dc converters. . New architecture for low-power high slew-rate operational transconductance amplifier. Novel architecture for high-efficiency active rectifier. The thesis is essentially based on the publications [1{9]. During the PhD program, other publications were generated [10{15] that are partially or non-included in the thesis. Additionally, some contributions presented in the text, are in process of publication.Hace ya un buen tiempo que las redes inalámbricas constituyen uno de los temas de investigación más estudiados en el área de las telecomunicaciones. Actualmente un gran porcentaje de los esfuerzos de la comunidad científifica y del sector industrial están concentrados en la definición de los requerimientos y estándares de la quinta generación de redes móviles. 5G implicará la integración y adaptación de varias tecnologías, no solo del campo de las telecomunicaciones sino también de la informática y del análisis de datos, con el objetivo de lograr una red lo suficientemente flexible y escalable como para satisfacer los requerimientos para la enorme variedad de casos de uso implicados en el desarrollo de la “sociedad conectada”. Un problema que se presenta en las redes inalámbricas actuales, que por lo tanto genera un desafío más que interesante para lo que se viene, es la escasez de espectro radioeléctrico para poder asignar bandas a nuevas tecnologías y nuevos servicios. El espectro está sobreasignado a los diferentes servicios de telecomunicaciones existentes y las bandas de uso libre o no licenciadas están cada vez más saturadas de equipos que trabajan en ellas (basta pensar lo que sucede en la banda no licenciada de 2.4 GHz). Sin embargo, existen análisis y mediciones que muestran que en diversas zonas y en diversas escalas de tiempo, el espectro radioeléctrico, si bien está formalmente asignado a algún servicio, no se utiliza plenamente existiendo tiempos durante los cuales ciertas bandas están libres y potencialmente podrían ser usadas. Esto ha llevado a que las Redes Radios Cognitivas, concepto que existe desde hace un tiempo, sean consideradas uno de los pilares para el desarrollo de las redes inalámbricas del futuro. En los ultimos años la transferencia inalámbrica de energía (WPT) ha cobrado especial atención, ya que logra aumentar la robustez, usabilidad y autonomía de los dispositivos móviles. Transferir energía inalámbricamente relaja el compromiso entre el tamaño de la batería y la disponibilidad de energía, permitiendo aplicaciones que de otro modo no serían posibles. Esta tesis tiene como objetivo desarrollar técnicas novedosas para aumentar la eficiencia y la distancia de transmisión de sistemas de transferencia inalámbrica por acople inductivo (IPT). Se abordó el diseño del enlace inductivo y varios circuitos utilizados en el receptor de energía. Además, realizamos un cuidadoso análisis a nivel sistema, teniendo en cuenta el diseño conjunto de diferentes bloques. Todo el trabajo está orientado hacia el desarrollo de aplicaciones de bajo consumo, como dispositivos médicos implantables activos (AIMD) o sistemas de identificación por radio frecuencia (RFID). Se consideraron principalmente tres enfoques para lograr mayor eficienciay distancia: 1) El uso de bobinas resonantes adicionales, colocadas entre el transmisor y el receptor. 2) El uso de redes de adaptación de impedancia en el receptor. 3) El diseño de circuitos rectificdores y conversores dc-dc con alta eficiencia.El efecto ocasionado por las bobinas resonantes adicionales en el enlace inductivo es usualmente abordado sin tener en cuenta su influenciaen todas las partes del sistema. En este trabajo, analizamos teóricamente y comparamos sistemas de 2 y 3 bobinas, mostrando las ventajas que tiene la bobina adicional en conjunto con el uso de redes de adaptación. El efecto de dicha bobina, en sistemas de lazo cerrado fue también estudiado, demostrando que el diseño del lazo debe considerar el número de bobinas que utiliza el link. Se trabajó con un sistema real de RFID, analizando el uso de una bobina resonante en una aplicación práctica existente y de amplio uso en el Uruguay