Automatic Positioning System for Inductive Wireless Charging Devices and Application to Mobile Robot

Inductive power transfer (IPT) remains one of the most common ways to achieve wireless power transfer (WPT), operating on the same electromagnetic principle as electrical transformers but with an air core. IPT has recently been implemented in wireless charging of consumer products such as smartphones and electric vehicles. However, one major challenge with using IPT remains ensuring precise alignment between the transmitting and receiving coils so that maximum power transfer can take place. In literature, much of the focus is on improving the electrical circuits or IPT coil geometries to allow a greater transmission range. Nevertheless, most IPT products today rely on precise alignment for efficient power transfer. In this thesis, the use of sensing coils to detect and correct lateral misalignments in a typical IPT system is modeled and tested. The sensing coils exploit magnetic-field symmetry to give a nonlinear measure of misalignment direction and magnitude. To test this idea, three experiments are performed: 1) measure the voltage of experimental sensing coils for various lateral misalignment distances, 2) implement closed-loop control and measure performance for an experimental two-dimensional (2D) automatic IPT alignment mechanism, and 3) test automatic IPT alignment on a plausible mobile robot wireless charging scenario. The experimental sensing coils give a misalignment sensing resolution of 1 mm or less in two lateral directions, allowing automatic alignment control in real time with a maximum lateral positioning error of less than √2 mm. This precise alignment allows for efficient power transfer to occur. When implemented on the mobile robot platform, the automatic positioning system gives similar results, allowing the robot to position itself above a wireless charger precisely—a task the mobile robot cannot accomplish using its navigation camera alone. The results of this experiment give confidence that similar sensing coils can be used to reduce lateral misalignments in scaled IPT systems, such as electric-vehicle wireless chargers

Cooperation and Storage Tradeoffs in Power-Grids with Renewable Energy Resources

One of the most important challenges in smart grid systems is the integration of renewable energy resources into its design. In this work, two different techniques to mitigate the time varying and intermittent nature of renewable energy generation are considered. The first one is the use of storage, which smooths out the fluctuations in the renewable energy generation across time. The second technique is the concept of distributed generation combined with cooperation by exchanging energy among the distributed sources. This technique averages out the variation in energy production across space. This paper analyzes the trade-off between these two techniques. The problem is formulated as a stochastic optimization problem with the objective of minimizing the time average cost of energy exchange within the grid. First, an analytical model of the optimal cost is provided by investigating the steady state of the system for some specific scenarios. Then, an algorithm to solve the cost minimization problem using the technique of Lyapunov optimization is developed and results for the performance of the algorithm are provided. These results show that in the presence of limited storage devices, the grid can benefit greatly from cooperation, whereas in the presence of large storage capacity, cooperation does not yield much benefit. Further, it is observed that most of the gains from cooperation can be obtained by exchanging energy only among a few energy harvesting sources

Feedback Control Goes Wireless: Guaranteed Stability over Low-power Multi-hop Networks

Closing feedback loops fast and over long distances is key to emerging applications; for example, robot motion control and swarm coordination require update intervals of tens of milliseconds. Low-power wireless technology is preferred for its low cost, small form factor, and flexibility, especially if the devices support multi-hop communication. So far, however, feedback control over wireless multi-hop networks has only been shown for update intervals on the order of seconds. This paper presents a wireless embedded system that tames imperfections impairing control performance (e.g., jitter and message loss), and a control design that exploits the essential properties of this system to provably guarantee closed-loop stability for physical processes with linear time-invariant dynamics. Using experiments on a cyber-physical testbed with 20 wireless nodes and multiple cart-pole systems, we are the first to demonstrate and evaluate feedback control and coordination over wireless multi-hop networks for update intervals of 20 to 50 milliseconds.Comment: Accepted final version to appear in: 10th ACM/IEEE International Conference on Cyber-Physical Systems (with CPS-IoT Week 2019) (ICCPS '19), April 16--18, 2019, Montreal, QC, Canad

Objective data sheet

The NXQ1TXA1 is a state of the art digital control controller for Qi-standard conforming wireless charger base stations. The controller supports type A1 or A10 single coil base stations. The NXQ1TXA1 offers wireless power transfer, WPC 1.1- Qi low power standard-compliant communication and safety functions including Foreign Object Detection (FOD), temperature monitoring and more. The controller supports the conventional WPC pinging mode during standby to identify potential receivers and also works with the NXP NFC TAGs to enabled by e.g. a NFC enabled phone so that the charger supports a zero power standby mode. The controller also offers a flexible User Interface (UI) with up to two LEDs and one buzzer for feedback and control. Depending on the required charging pad area, coil configurations such as A1 (single coil with magnet) and A10 (single coil without magnet) are supported. 2. Features and benefits Qi conforming wireless charger controller and communication

Smart Bottle Firmware and Wireless Charging Integration

In the past 3 decades, there has been a 60% increase of infants under the age of 2 who are considered obese [1]. The California Polytechnic State University, San Luis Obispo Child Development Department wants to research parents feeding habits and the Smart Bottle tool was built to aid this effort in finding the relationship between infant obesity and parent feeding habits. The Smart Bottle is a baby bottle meter attached to the bottom of the bottle. The goal of this device is to analyze the state of the feeding the parent is currently at and measure the amount of food the baby has consumed. The most recent iteration of the Smart Bottle (V5) is fully functional and attachable to infant feeding bottles to collect feeding data stored via SD card. V5 also implements a Bluetooth module for wireless data transfer, however, it does not have a User Interface. This project looks to build Smart Bottle (V6) which implements a wireless charging module integrated alongside a User Interface (UI). The wireless charging allows for a fully sealed enclosure reducing the risk of any electrical hazards whereas the UI allows for faster duplex communication. Wireless charging will be implemented through inductive charging, a wireless energy transfer that uses electromagnetic induction to generate power. This project allows for the Child Development researchers to have a convenient method of data extraction while also protecting the consumers

Underwater Communications based on Resonant Inductive Links

Em anos mais recentes, os veículos não tripulados têm sofrido um avanço considerável no seu desenvolvimento. Devido ao subsequente aumento de interesse na exploração do oceano, em especial zonas de condições extremas cujo acesso está impossibilitado. Em concreto, nas aplicações subaquáticas, existem problemas substanciais relativos ao carregamento de forma wireless dos aparelhos, mais especificamente, à monitorização deste processo, assim como, na transferência dos dados recolhidos. Esta dissertação apresenta uma solução para o controlo de parâmetros associados ao carregamento wireless, reaproveitando o acoplamento indutivo ressonante para, além da transferência de potência já implementada, transmitir dados. Denote-se que o estudo e implementação foram desenvolvidos num sistema com um comutador de alta tensão, optimizado para uma resistência de carga igual a 12.5 Ohm, uma frequência de ressonância de 240 kHz para uma transferência de potência na ordem dos 80 W com uma eficiência máxima no acoplamento de 94%. O trabalho desenvolvido explora um patamar substancial de corrente disponível, desde 0.5 A a 2.5 A com um conjunto de resistências entre 1 Ohm a 11 Ohm. Com estes valores é possível determinar diferentes estados que, por sua vez, permitem uma comunicação wireless com um grande alcance dinâmico. A eficiência geral do acoplamento não sofre uma grande alteração para os diferentes estados necessários para o envio de informação. Sabendo que o teor de sal afeta diretamente o acoplamento e, consequentemente, os níveis de corrente do sistema, e ainda que os valores de salinidade do mar variam de região para região, é possível regular esta variação mudando o valor da resistência responsável pela modulação da carga, reforçando a modularidade do sistema. Este desenvolvimento apresenta uma solução simples e viável, apresentando-se como uma forte alternativa ao uso de circuitos externos adicionais.During more recent years there has been a considerable advancement in unmanned vehicles, more so in autonomous underwater vehicles, following the increasing interest in exploring unreachable parts of the ocean. Underwater autonomous work poses substantial obstacles when it comes to wirelessly charging the devices and most importantly to the monitoring of such operation, as well as the transfer of the data gathered. This thesis presents a solution for overseeing the parameters that come with the wireless charging of a system, repurposing the resonant inductive link to transmit bits of data in addition to the power transfer already in place. Furthermore, the work was developed on system designed with a high-voltage switching power driver, optimized for load resistance equal to 12.5 Ohm, having a resonance frequency of 240 kHz for a power transfer in the order of 80 W with a link efficiency up to 94%. The present work explores the substantial threshold of current available at the primary coil, from 0.5 A to 2.5 A with a variation of resistance from 1 Ohm to 11 Ohm seen at the secondary coil. This allows for a detection of different states which provide a wireless communication with a wide dynamic range. The overall efficiency of the link is not greatly affected by the different states necessary to transmit information. Knowing that the salinity value of the sea differs from region to region and in turn, both the levels of current and threshold are affected, it is possible to regulate the value of the resistance responsible for the load modulation to atone such difference, which makes for a system with a high level of modularity. This presents a simple and viable solution that is a clear alternative to the need of additional aftermarket circuits to monitor and assist the charging of devices underwater

A Review of Commercial Electric Vehicle Charging Methods

Electric Vehicles (EVs) are rapidly becoming the forerunners of vehicle technology. First electric vehicles were overlooked because of not having adequate battery capacity and because of low efficiency of their electric motors. Developing semiconductor and battery technologies increased the interest in the EVs. Nevertheless, current batteries still have insufficient capacity. As a result of this, vehicles must be recharged at short distances (approximately 150 km). Due to scheduled departure and arrival times EVs appear to be more suitable for city buses rather than regular automobiles. Thanks to correct charging technology and the availability of renewable energy for electric buses, the cities have less noise and CO2 emissions. The energy consumption of internal combustion engines is higher than of the electric motors. In this paper, studies on the commercial electric vehicle charging methods will be reviewed and the plug-in charging processes will be described in detail. This study strives to answer the questions of how plug-in charging process communication has performed between the EV and Electric Vehicle Supply Equipment (EVSE).</p