Suchergebnisse

IEEE Applied Power Electronics Conference and Exposition, San Antonio, (Estados Unidos de Norteamérica), marzo de 2018 ; Visible Light Communication (VLC) has gained relevance during last years. It consists in using High-Brightness LEDs (HB-LEDs) both for lighting and for transmitting information changing the light intensity rapidly. However, there are some bottlenecks that are slowing down the deployment of this technology. One of the most important problems is that the HB-LED drivers proposed for addressing high data rates in VLC achieve poor power efficiency. Since these HB-LED drivers must be able to reproduce fast current waveforms, the use of Linear Power Amplifiers (LPAs) has been adopted, which clearly damage the power efficiency of HB-LED lighting. In order to alleviate this problem, a HB-LED driver made up of two DC-DC power converters is presented in this work. One of them is responsible for performing the communication functionality by operating at high switching frequency (10 MHz), whereas the second one fulfills the illumination functionality by ensuring a certain biasing point. The split of the power allows to minimize the power delivered by the fast-response DC-DC power converter. Thus, the efficiency can be maximized for scenarios with changing conditions (i.e., mobile transmitter and/or receiver, presence of mobile obstacles, etc.). In this sense, how the lighting level and the communication signal power affect both the power efficiency and the communication efficiency is deeply analyzed. The implemented prototype achieves an overall efficiency around 90%. In addition, the proposed VLC transmitter is able to reproduce a wide range of digital modulation schemes, including Orthogonal Frequency Division Multiplexing (OFDM) ; This work has been supported by the Spanish Government under the Project MINECO-17-DPI2016-75760-R, the scholarship FPU14/03268 and the Principality of Asturias under the Project FC-15- GRUPIN14-143, the Project SV-PA-17-RIS3-4 and by European Regional Development Fund (ERDF) ...

This work was supported in part by the Spanish Government under Project MCI-20-PID2019-110483RB-I00 and in part by the Principality of Asturias under Severo Ochoa Program under Grant BP20-181.

Visible Light Communication (VLC) takes advantage of the widespread use of the LEDs, and by modifying the driver stage, the LEDs are capable of lighting and transmitting information. One of the main drawbacks is the low power efficiency due to the modification of the LED driver stage in order to add the communication capability. Most of the research work related to VLC is towards the communication task, whereas there is a limited work about the improvement on the power efficiency. This paper proposes a high efficiency LED driver for VLC working as a transmitter based on the outphasing technique. This technique is used also in RF communications and increases the efficiency of the amplifiers. The proposed transmitter is made up of two switching-mode power amplifiers that reproduce the signals required for the outphasing technique and a DC/DC converter that biases the LEDs. The proposal exploits the light and, instead of being added electrically, the signals are added in their light form, which leads to a reduction in the complexity of the design. As experimental results, a transmitter was built of two Class E amplifiers reproducing a 16-QAM modulation, achieving a signal-generation efficiency of 78% and an overall efficiency of 92% ; This work was supported in part by European Regional Development Fund grants, in part by the Spanish Government under project MINECO-17- DPI2016-75760-R, and in part by the Principality of Asturias under project IDI/2018/000179 and scholarship BP17-91

IEEE Energy Conversion Congress and Exposition (XI. 2019. Baltimore, Estados Unidos) ; This work was supported in part by the European Regional Development Fund grants, in part by the Spanish Government under the project MINECO- 17-DPI2016-75760-R, and in part by the Principality of Asturias under the project IDI/2018/000179 and under the scholarship BP17-91

Simposium Nacional de la Unión Científica Internacional de Radio, URSI (34º. 2019. Sevilla) ; This work has been supported by the Spanish Government under the Project MINECO-17-DPI2016-75760-R, the Principality of Asturias under the Project IDI/2018/000179, the grant BP17-91 and by European Regional Development Fund (ERDF) grants

The Ripple Modulation (RM) is a technique that provides a variable output voltage by using the output voltage ripple of a Switching-Mode Power Converter (SMPC). It was proposed to reproduce the communication signal of a Visible Light Communication (VLC) transmitter, thus avoiding the use of power inefficient Linear Power Amplifiers (LPAs). However, the RM has a major drawback: it has not been reported how to reproduce Multi-Carrier Modulation (MCM) schemes, which are the preferred modulation schemes due to their high performance in wireless communications. In this work, it is demonstrated that the RM can be used to reproduce MCM schemes by considering the envelope and the instantaneous phase of the communication signal. Moreover, the control system of the power stage is described in detailed, explaining how to modulate both the width and the phase of the gate signals, the calculation of the phase-shift that is required for tracking the envelope, etc. ; This work was supported by the Spanish Government under the Project MINECO-17-DPI2016-75760-R, the scholarship FPU14/03268, the Principality of Asturias under the Project IDI/2018/000179, the grant BP17-91 and by European Regional Development Fund (ERDF)

Annual Conference of the IEEE Industrial Electronics Society (IES) (45th. 2019. Lisboa) ; A high efficiency linear-assisted Visible Light Communication (VLC) LED driver working as a transmitter is presented in this work. A linear-assisted transmitter is based on the idea of using a high efficiency but bandwidth limited circuitry which delivers most of the power and a low efficiency but fast linear amplifier (linear assistance) which corrects the distortion of the signal. The presented solution takes advantage of the light in a VLC system by summing the contribution of the linear amplifier in light instead of electrically, which leads to a electrical isolation between both stages and a reduction of the complexity comparing to the traditional approach used in Envelope Tracking (ET) and Envelope Elimination and Restoration (EER) techniques. As experimental results, the design of a linear-assisted Class E amplifier delivering a 16-PSK phase digital modulation with a 1 MHz carrier is presented. On one hand, the Class E amplifier delivers most of the power (92% of the signal power) at high efficiency (81%) and, on the other hand, the linear amplifier only delivers the error signal at lower efficiency. The efficiency of the signal circuitry is up to 75% and the efficiency of the whole system considering the signal and the LED biasing circuitry is up to 85% ; This work was supported in part by European Regional Development Fund grants, in part by the Spanish Government under project MINECO-17- DPI2016-75760-R, and in part by the Principality of Asturias under project IDI/2018/000179 and scholarship BP17-91

Visible light communication (VLC) based on solid-state lighting (SSL) is a promising option either to supplement or to substitute existing radio frequency (RF) wireless communication in indoor environments. VLC systems take advantage of the fast modulation of the visible light that light emitting diodes (LEDs) enable. The switching-mode dc-to-dc converter (SMCdc-dc) must be the cornerstone of the LED driver of VLC transmitters in order to incorporate the communication functionality into LED lighting, keeping high power efficiency. However, the new requirements related to the communication, especially the high bandwidth that the LED driver must achieve, converts the design of the SMCdc-dc into a very challenging task. In this work, three different methods for achieving such a high bandwidth with an SMCdc-dc are presented: increasing the order of the SMCdc-dc output filter, increasing the number of voltage inputs, and increasing the number of phases. These three strategies are combinable and the optimum design depends on the particular VLC application, which determines the requirements of the VLC transmitter. As an example, an experimental VLC transmitter based on a two-phase buck converter with a fourth-order output filter will demonstrate that a bandwidth of several hundred kilohertz (kHz) can be achieved with output power levels close to 10Wand power efficiencies between 85% and 90%. In conclusion, the design strategy presented allows us to incorporate VLC into SSL, achieving high bit rates without damaging the power efficiency of LED lighting ; This work has been supported by the Spanish Government under Project MINECO-15-DPI2014-56358-JIN, the scholarship FPU14/03268 and the Principality of Asturias under the Project SV-PA-17-RIS3-4 and by European Regional Development Fund (ERDF) grants

47th Annual Conference of the IEEE Industrial Electronics Society, IECON (Troronto, Canadá, 13-16 octobre 2021) ; The Two-Input Buck (TI Buck) Converter has low voltage stress over the switches, very high efficiency, and low harmonic components. Therefore, it is a prominent topology to work as a post-regulator in Visible Light Communication (VLC) systems. This works proposes a combination of an Asymmetrical Half Bridge (AHB) and a resonant dc-dc unregulated converter (DCX) to supply the two input voltage sources of the TI Buck based post-regulator. Due to the similarity in the primary side of these two converters (i.e AHB and DCX), the auxiliar DCX subcircuit will be coupled to the AHB without increasing the number of controlled switches. The topology, as well as the design constraints are studied in this paper. As example, a 45W AHB with an auxiliar DCX source is build. The topology reaches 94% of efficiency with the proposed independent behavior between the output voltages. ; This work has been carried out by funding from the Spanish government through the RTI2018-099682-A-I00 project, under the PRE2019-088425 grant, and by the Principality of Asturias under the scholarship BP17-91.

It is well known that modern wireless communications systems need linear, wide bandwidth, e cient Radio Frequency Power Amplifiers (RFPAs). However, conventional configurations of RFPAs based on Class A, Class B, and Class AB exhibit extremely low e ciencies when they manage signals with a high Peak-to-Average Power Ratio (PAPR). Traditionally, a number of techniques have been proposed either to achieve linearity in the case of e cient Switching-Mode RFPAs or to improve the e ciency of linear RFPAs. There are two categories in the application of aforementioned techniques. First, techniques based on the use of Switching-Mode DC–DC converters with a very-fast-output response (faster than 1 s). Second, techniques based on the interaction of several RFPAs. The current expansion of these techniques is mainly due to their application in cellphone networks, but they can also be applied in other promising wireless communications systems such as Visible Light Communication (VLC). The main contribution of this paper is to show how Envelope Tracking (ET), Envelope and Elimination (EER), Outphasing, and Doherty techniques can be helpful in developing more e cient VLC transmitters capable of reaching high bit-rates (higher than 1 Mbps) by using advance modulation schemes. Finally, two examples based on the application of the Outphasing technique and the use of a Linear-Assisted Envelope Amplifier (EA) to VLC are presented and experimentally verified ; This work was funded by the Spanish Government under Project MINECO-17-DPI2016-75760-R, by the Principado de Asturias under Projects SV-PA-17-RIS3-4 and FC-GRUPIN-IDI/2018/000179, and the scholarship BP17-91, as well as by European Regional Development Fund (ERDF) grants

Lava caves are the result of a geological process related to the cooling of basaltic lava flows. On the Moon, this process may lead to caves several kilometers long and diameters of hundreds of meters. Access to lava tubes can be granted through skylights, a vertical pit between the lava tube and the lunar surface. This represents an outstanding opportunity for long-term missions, for future permanent human settlements, and for accessing pristine samples of lava, secondary minerals and volatiles. Given this, the ESA launched a campaign through the Open Space Innovation Platform calling for ideas that would tackle the many challenges of exploring lava pits. Five projects, including Robocrane, were selected. Solar light and direct line of sight (for communications) with the lunar surface are not available inside lava tubes. This is a problem for any robot (or swarm of robots) exploring the lava tubes. Robocrane tackles both problems by deploying an element (called the Charging head, or CH) at the bottom of the skylight by means of a crane. This CH behaves as a battery charger and a communication relay for the exploring robots. The required energy is extracted from the crane's solar panel (on the surface) and driven to the bottom of the skylight through an electrical wire running in parallel to the crane hoisting wire. Using a crane allows the system to deal with unstable terrain around the skylight rim and protect the wires from abrasion from the rocky surface and the pit rim. The charger in the CH is wireless so that the charging process can begin as soon as any of the robots get close enough to the CH. This avoids complex and time-consuming docking operations, aggravated by the skylight floor orography. The crane infrastructure can also be used to deploy the exploring robots inside the pit, reducing their design constraints and mass budget, as the robots do not need to implement their own self-deployment system. Finally, RoboCrane includes all the sensors and actuators for remote operation from a ground station. RoboCrane has been designed in a parametric tool so it can be dynamically and rapidly adjusted to input-variable changes, such as the number of exploring robots, their electrical characteristics, and crane reach, etc. ; This work was supported in part by the Spanish Government under the Project MCIU-19-RTI2018-099682-A-I00 and by ESA under project CN-UE-20-ROBOCRANE.

This work was supported in part by the Spanish Government under the Project MCIU-19-RTI2018-099682-A-I00 and by ESA, Spain under ESA CONTRACT No 4000130860/20/NL/GLC .