USV charging based on WPT system

With the increasing demand of water and underwater exploration, more and more electric unmanned surface vehicles (USV) are put into use in recent years. However, because of the present battery technology limits, these devices require to be recharged frequently that is a challenging problem taking into account the complex water environment where these equipments are acting. To improve safety and convenience of USV charging a wireless power transfer (WPT) system is proposed in this dissertation. In this case, the boat can be controlled to go to the charging facilities. During charging by the implemented WPT system, the state of charging can be remotely monitored by host computer. The moving control is based on embedded system. The relative position between transmitting coil and receiving coil is supposed to be sensed by magnetic sensor, since the relative position has great impact on transmission efficiency. The remote monitoring software was implemented in the host computer and was developed in LABVIEW. A graphical user interface was developed to control the boat moving and collect the data from the WPT and the boat sensors. The effectiveness of the proposed system was tested for instance in the laboratory environment and in-field tests are also planned in the near future.Com a crescente procura da exploração em ambientes aquáticos e subaquáticos , os veículos elétricos de superfície não tripulados ("electric unmanned surface vehicle" -USV) têm sido cada vez mais utilizados nestes últimos anos. No entanto, devido aos limites atuais relacionados com a tecnologia utilizada nas baterias, os dispositivos precisam de ser recarregados com frequência para poderem operar num ambiente aquático complexo. Para melhorar a segurança e a conveniência do carregamento da bateria de um USV, um sistema para recarregamento da bateria de um barco não tripulado através de transferência de energia sem fios("wireless power transfer" - WPT) é proposto nesta dissertação. Neste caso de estudo, o barco tem a capacidade de ser controlado para chegar a um ponto de recarregamento da bateria, que se encontra fixado por uma doca mecânica. Enquanto o sistema WPT érecarregado, os dados associados ao processo de recarregamento da bateria podem ser monitorizados por um computador host. O controlo da movimentação do barco é baseado num sistema embebido. A posição relativa entre a bobina transmissora e a bobina receptora deve ser detectada pelo sensor magnético, uma vez que a posição relativa tem um grande impacto na eficiência da transmissão. Em termos do computador host, foi utilizado o software LABVIEW para programar a interface que permite controlar o movimento do barco e recolher os dados. Finalmente, a eficácia do sistema proposto foi experimentada e testada num ambiente de laboratório

ESSE 2017. Proceedings of the International Conference on Environmental Science and Sustainable Energy

Environmental science is an interdisciplinary academic field that integrates physical-, biological-, and information sciences to study and solve environmental problems. ESSE - The International Conference on Environmental Science and Sustainable Energy provides a platform for experts, professionals, and researchers to share updated information and stimulate the communication with each other. In 2017 it was held in Suzhou, China June 23-25, 2017

Quantitative Two-Layer Inversion and Customizable Sensor-Array Instrument for Electromagnetic Induction based Soil Conductivity Estimation

Electromagnetic (EM) measurement methods oer the great potential to non-invasively and contactlessly obtain geological and hydrological soil properties of the uppermost six meters of the subsurface with an areal resolution in the sub-meter range. The presented work is focused on small-sized frequency domain `electromagnetic induction' (EMI) systems which combine the transmitter (Tx) and receiver (Rx) unit in one portable construction and obtain the apparent electrical conductivity ($\sigma_{a}$) of the sensed soil volume by inducing electrical currents and measuring the responding electromagnetic field. The sensing depth of EMI instruments depends on the sensor conguration and in particular the coil orientation and Tx-Rx separation. In principle, multi-conguration EMI data can be inverted for the electrical conductivity distribution over depth. However, there is a demand for efficient inversion algorithms and high-quality EMI data from different sensing depths to perform such an inversion. Here, a novel one-dimensional global-local inversion approach is implemented which evaluates the mist between EMI data and forward modeled data for a two-layer soil using a L1-norm objective function. The global approach is based on a grid search for reasonable model parameters in combination with the local-sensitivity forward model. The two soil models with the smallest misfit are refined using the (local) simplex search algorithm with the more precise full solution electromagnetic forward model. The algorithm is analyzed using synthetic EMI data. Applying the inversion on quantitative EMI transect data from two commercial devices with eight different sensor configurations results in a two-layer electrical conductivity model with lateral and vertical conductivity changes that are in good agreement with a collocated electrical resistivity tomography data set. To improve the depth-resolution beyond available fixed congurations, a novel EMI prototype system (ElMa1) with customizable sensor-array is developed, containing multiple modular sensor units which can be flexibly arranged by the operator for each survey, ensuring optimal depth-sensitivity (i.e. coil orientations and Tx-Rx separations) for the specific investigation. The sensor units consist of coil-based transmitter and receiver circuits which allow for the measurement of the magnetic flux and the sensor impedance in a frequency range between 3 and 33 kHz, respectively. To allow for flexible sensor congurations, data processing and signal optimization, the transmitter current and the receiver voltages are separately digitized using 24-bit analog-to-digital converters (ADC's) which provide a high dynamic range and phase stability. For a measurement time of 0.5 s, the ElMa1 system achieves an instrumental $\sigma_{a}$-accuracy of 1 mS/m at 20 kHz for the intended Tx-Rx separation of 1.0 m and an accuracy of 10 mS/m for a less favorable conguration with smaller Tx-Rx separation of 0.3 m and smaller measurement frequency of 5 kHz, both observed under stable temperature conditions. In addition, experimental data were corrected for temperature-induced system drifts by simulating the electrical circuit of the sensor system using spectral measurements [...

A design technique for geometric optimisation of resonant coil sizes in low to mid frequency inductive power transmission systems.

Wireless power transfer (WPT) is a well-established method of energising electrically-powered devices. Among the different available WPT techniques, Resonant Inductive Power Transfer (RIPT) has been adapted for use in a wide range of applications. The primary reason is the relatively higher Power Transfer Efficiency (PTE) that RIPT can provide. RIPT systems operate on the principle of magnetic resonance coupling between a Transmitter (Tx) and a Receiver (Rx) coil. Maximising the PTE is a key driver for improving the performance of RIPT systems. In a RIPT link the PTE is influenced by three factors: (i) inductive linkage between the Tx and Rx, (ii) terminating circuitry of Tx and Rx sides and (iii) the Tx/Rx coil's geometrical size. In considering these impacting factors, different techniques to improve PTE have been extensively presented in the literature and are comprehensively reviewed in this thesis. The research work undertaken focuses on the geometrical optimisation of Tx/Rx coils to help maximise PTE in RIPT systems for operation over low- and mid-frequency bands (i.e. between few kHz to several MHz). Conventional methods for maximising PTE require defining various design parameters (i.e. figure-of-merits), which assist in finding the optimum Air-Cored Coil (ACC) geometry. However, traditional techniques for working with Figure-of-Merit (FoM) parameters are very time-consuming and process-demanding. In this thesis, the number of required FoMs have been reduced to one and incorporated into a process that will accelerate production of the optimum geometry design. A unique FoM parameter (i.e. Pscf) is developed by consolidating the PTE's impacting factors. Considering the RIPT application and its physical size constraints, a proper selection method for identifying the numerical value of Pscf is investigated. A novel iterative algorithm has been developed to assist in selection of the most favourable Pscf value, which provides the optimum ACC geometry. Theoretical design examples of two RIPT systems - operating at 10 kHz (low-frequency band) and 300 kHz (mid-frequency band) - are used to investigate the functionality of the ACC design approach, for which successful results are achieved. The novel iterative algorithm is also experimentally validated by developing four prototyped Tx/Rx ACC pairs, with real-world applications, which operate over low- and mid-frequency bands: 1:06 MHz, 100 kHz, 50 kHz, 15 kHz. For the designed ACC geometries, maximum PTEs of 85:63% at 1:06 MHz, 83:10% at 100 kHz, 72:85% at 50 kHz and 34:57% at 15 kHz are practically measured in bench top tests. The measured PTE values are in close correlation (within 14%) with the calculated PTEs at these frequency ranges, and thus validate the novel ACC design procedure. The RIPT system's maximum achievable PTE can be further increased by adding ferrite cores to the Tx/Rx ACC pair. In this thesis, an advanced iterative algorithm is also presented to support the design of geometrically optimised coil pairs employing ferrite cores. The advanced iterative algorithm is an extension of the initial work on optimising ACC geometries. Optimum Ferrite-Cored Coil (FCC) geometries, produced using the advanced iterative algorithm, for RIPT systems operating at 10 kHz and 300 kHz have been investigated. In comparing the FCC and ACC geometries designed for these frequencies, it is demonstrated that RIPT systems with ferrite cores reduce the ACC's geometrical size and additionally improve PTE. To validate the performance of the advanced FCC design algorithm over low- and mid-frequency bands, two RIPT systems are physically constructed for operation at 15 kHz (low-frequency) and 50 kHz (mid-frequency). For the prototyped RIPT systems, maximum PTEs of 45:16% at 50 kHz and 50:74% at 15 kHz are practically measured. The calculated and physically measured PTE values are within 2% difference; hence validating the advanced FCC design process

Active magnetic bearing design and characterization for high temperature applications

This thesis is motivated by one of the largest markets: aviation. This market, in which competition and investments are extraordinary, requires constant technical improvements in order to increase its competitiveness. Jet engines have an important influence on fuel consumption and servicing of airplanes, thus on the transportation cost. The present work was supported by the European Community [9]. This thesis investigates the use of active magnetic bearings for jet engines. It is expected that magnetic bearings could considerably reduce losses and service intervals in jet engines. The present work concentrates on the design and characterization an active magnetic bearing for applications at high temperature. The report begins with an introduction locating the accomplished work into the current economic and technical context. The advantages of such system are given, as well as the scientific contribution of the research which has been undertaken. An introduction to magnetic bearings is given, so that the key elements of the dimensioning of such a system are comprehensible for readers of all horizons. The maximum force produced by magnetic bearings is mainly limited by the heating related to the losses in the coils. A thermal model for high temperature magnetic bearings has been implemented. An experimental part allowed the validation of this model for a wide temperature range. The construction of a magnetic bearing requires various types of materials; soft magnetic materials, electrical conductors, electrical insulators as well as several fixation materials. Tests have been carried out and a catalogue lists the materials available for high temperature magnetic bearings. Position sensors are usually used in magnetic bearings. Eddy current position sensors have been developed. They were realized with coils printed on a ceramics substrate by using thick-film technology. Measurements done at high temperature show the great characteristics of these sensors. Problems of silver migration between the wires welding have been encountered during tests carried out at high temperature. Various solutions have been tested with the aim of avoiding the silver migration. The materials exposed at high temperature have unfortunately sometimes a limited lifespan. Studies of failures related to an exposure at high temperature have been done. Some failures are detectable by the magnetic bearing. An example of detection of possible short-circuits in the actuator coils is presented. Finally a prototype of an active magnetic bearing system with five degrees of freedom has been built. A furnace especially developed, makes it possible to create environments at high temperature. The characteristics of the active magnetic bearing have been measured during levitation at ambient temperatures from 25°C up to 550°C

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

NASA Tech Briefs, January 1995

Topics include: Sensors; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences; Books and Report

Index to NASA Tech Briefs, 1972

Abstracts of 1972 NASA Tech Briefs are presented. Four indexes are included: subject, personal author, originating center, and Tech Brief number

Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences