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High-Brightness Light Emitting Diodes (HB-LEDs) are considered the future trend in lighting not only due to their high efficiency and high reliability, but also due to their other outstanding characteristics: chromatic variety, shock and vibration resistance, etc. Nevertheless, they need the development of new power supplies especially designed for boosting and taking advantage of their aforementioned characteristics. Besides, their behaviour is completely different from the rest of lighting devices and, consequently, it should be also taken into account in the design of the converters used to drive them. As a result, many well-known topologies have been optimized or redesigned in order to be used in LED–lighting applications and many new topologies have come up in the recent years with the same purpose. In this paper, the main HB-LED characteristics will be explained, highlighting how they influence the design of their power supplies. After, the main topologies will be presented from the simplest to the most complex ones, analysing their advantages and disadvantages ; This work has been supported by Spanish Government under projects RUE-10-CSD2009-00046 FEDER Funds, MICINN10-DPI2010-21110-C02-01 and student grant FPI BES-2011-044114

This work was supported in part by the Spanish Government under projects MINECO-17-DPI2016-75760-R and RTI2018-099682-A-I00; in part by the Principality of Asturias under project IDI/2018/000179 and Severo Ochoa grant BP14-085; and in part by the European Regional Development Fund Grants (FEDER).

A simple, analog, control circuit is proposed for seamless transition between source and sink modes in a Quasi-Square-Wave Zero Voltage Switching (QSW-ZVS) source/sink dc-dc converters. The inductor current is controlled by a variable-width hysteretic current mode control. The upper and lower bounds of the hysteretic band are clamped to ensure QSW-ZVS operation with a single current command and independently from the power flow direction. This enables the control of any PWM converter able to operate in QSW-ZVS with a single control loop. Implementing a complex multi-mode or look-up-table based digital control is no longer required. A 50W buck converter and a 100W boost converter are built to demonstrate the proposed control circuit ; This work was supported in part by the Spanish Government under Project MINECO-17-DPI2016-75760-R, in part by the Principality of Asturias under Severo Ochoa grant BP14-085 and by European Regional Development Fund (ERDF) grants

High-Brightness Light Emitting Diodes (HB-LEDs) are considered as a remarkable lighting device due to their high reliability, chromatic variety and increasing efficiency. As a consequence, a high number of solutions for supplying LED strings are coming out. One-stage solutions are cost-effective, but their efficiency is low as they have to fulfill several purposes with only one converter: Power Factor Correction (PFC), galvanic isolation (in some cases) and current regulation. Two-stage and three-stage solutions have higher efficiency as each stage is optimized for just one or two tasks and they are the preferred option when supplying several strings at the same time. Nevertheless, due to their higher cost in comparison to one-stage solutions, they are used when high-efficiency, high-performance and the possibility of supplying several strings are the main concerns. Besides, they are also used when high reliability is needed and electrolytic capacitors cannot be used. In this paper, a three-stage solution and its complete design guideline for LED-based applications is proposed. PFC is achieved by a Boost converter while the galvanic isolation is provided by an Electronic Transformer (second stage). The third stages (one for each LED string) are designed following the TIBuck schematic, but taking advantage of the load characteristics (i.e., the high value of the LED string knee voltage, approximately equal to half the string nominal voltage). Besides, a variation of the analog driving technique is also proposed. Experimental results obtained with a 160-W prototype show an efficiency as high as 93% for the whole topology and 95% for the cascade connection of the second and third stages ; This work has been supported by the AEG Power Solutions B.V. under project FUO-EM-002-10 and by Spanish Government under projects CONSOLIDER MICINN-10-CSD2009-00046 and MICINN-10- DPI2010-21110-C02-0

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.

IEEE Applied Power Electronics Conference and Exposition (APEC) (35th. 2020. New Orleans, USA) ; This work has been supported by the Spanish Government under projects MCIU-19-RTI2018-099682-A-I00 and FC-GRUPIN-IDI/2018/000179.

The use of battery–cell equalizers is mandatory in order to assure that all the cells connected in series are charged to its maximum capacity, even when they present small differences in this parameter due to several factors, such as aging, manufacturing, or temperature. Active equalizers, with a higher efficiency in comparison to passive ones, have the disadvantage of using a considerable number of components. Moreover, in the case of active equalizers with very high performance, this number can be even higher. In this paper, the use of the wave-trap concept, widely used in telecommunication systems, is studied. This concept allows the battery–cell equalizer to use its switching frequency as the control variable that decides which cell is being charged. Hence, it is not necessary to use a complex system based on a high number of controlled switches in order to determine which cell is being charged. In this way, the number of switches (and the corresponding driving signals) can be strongly minimized without reducing the performance of the system. In order to proof the validity of this concept (i.e., wave traps) in the design of battery–cell equalizers, a topology based on a half-bridge structure is also proposed in this paper. It uses only two controlled switches in order to decide which cell is charged. Experimental results are provided for a four-cell equalizer as a proof of concept ; Spanish Government under Project CONSOLIDER [MICINN-10-CSD2009-00046]; Spanish Government under Project ARROW-HEAD [GA: 332987]; Spanish Government under Project ANRI-DOC [DPI2013-47176-C2-2-R]; European Union under Project SPEED [FP7-NMP3-LA-2013-604057]

Nowadays, the solid-sate lighting technology evolution has changed traditional solutions in lighting. High-Brightness Light–Emitting Diodes (HB-LEDs) have become very attractive light sources due to their excellent characteristics: high efficiency, high life-time and low maintenance. It is evident that HB-LED drivers must be durable and efficient to achieve these advantages. Moreover, for replacing incandescent bulbs, the ac-dc HB-LED driver must be low cost and comply with international regulations (i.e. injection of low frequency harmonics into the mains). Traditionally, authors have focused its efforts on increasing efficiency. All these solutions obviate the elimination of traditional electrolytic capacitor of ac to dc converters, highlighting that this is the price to pay for a very low-cost solution. This paper presents a new proposal to design a simple and low-cost ac to dc HB-LED driver for retrofit lamps without electrolytic capacitor. The proposed solution comes from a very well-known technique used in the past: Active Input Current Shapers (AICS), but in this case without electrolytic capacitor. If the electrolytic capacitor of an AICS is removed, then low frequency ripple arises in its intermediate dc bus, increasing the distortion of the line input which already has appreciable distortion. However, the increase of distortion is very slight. Also, the low frequency ripple is not transferred to the output due to the high output dynamic response of AICS, avoiding flickering. This paper presents a theoretical analysis that guarantees a trade of between compliance with international regulations and the use of other capacitor technologies different from the electrolytic one. Finally, a 24W experimental prototype has been built and tested in order to validate the theoretical results presented in this digest ; Spanish Ministry of Education and Science under Project MINECO-13-DPI2013-47176- C2-2-R, by Government of the Principality of Asturias under the Project FC-15-GRUPIN14-143 and by European Regional ...

Active equalizers, with a higher efficiency in comparison to passive ones, have the disadvantage of using a considerable number of components. The wave-trap concept allows the battery cell equalizer to use its switching frequency as the control variable that decides which cell is being charged. Hence, the number of controlled switches is strongly reduced without reducing the performance of the system. In this paper, an optimized design guideline for an equalizer based on this concept is presented. First, the mathematical equations that describe the behavior of each trap are introduced. Then, these equations are used for calculating the optimum value of all the parameters of the system. This optimum calculation is based on relating the injected energy in the battery cell and the resonant energy of the chosen trap. This design guideline has been used in the development of a 4-battery-cell equalizer based on a half-bridge structure ; Spanish Government under projects CONSOLIDER MICINN-10-CSD2009-00046 and ANRI-DOC (DPI2013- 47176-C2-2-R), by European Union under project SPEED (FP7-NMP3-LA- 2013-604057) and by IKERLAN and ORONA under project FUO-EM-072- 13

This work was supported by the Spanish Government under projects MCIU-19-RTI2018-099682-A-I00, FC-GRUPIN-IDI/2018/000179, and PAPI-18-PF-10 and by the European Commission FP7 Large Project NMP3-LA-2013-604057, under grant UE-14-SPEED-604057.

Workshop on Control and Modeling for Power Electronics, COMPEL (9th, 2028, Padua) ; This work was supported by the Spanish Government under projects DPI2014-56358-JIN. It was also supported by the European Commission under FP7 Large Project, grant UE-14-SPEED-604057.

Seminario Anual de Automática, Electrónica Industrial e Instrumentación, SAAEI (25º. 2018. Barcelona) ; This work was supported by the Spanish Government under projects DPI2014-56358-JIN and MINECO-17- DPI2016-75760-R and by the European Commission FP7 Large Project under grant UE-14-SPEED-604057

High Brightness Light-Emitting Diodes (HB-LEDs) are becoming omnipresent across all aspects of illumination products, due to their incredible characteristics: efficiency, reliability, long lifetime, controllability, etc. This paper proposes power conversion topologies to drive medium to high power HB-LEDs in three phase power grids when these connection is available. For that reason, an evaluation of several drivers for medium to high power HB-LEDs in three-phase power grids is done. Moreover, a new topology is proposed which complies with IEC 1000-3-2 Class C requirements, achieves high Power Factor (PF), low Total Harmonic Distortion (THD), as well as, the capability to have a flicker free behaviour while disposing of the bulk capacitor and having galvanic isolation. The HB-LED driver is based on a modular approach with several cells working together with their inputs connected to the three-phase network and their outputs connected in parallel generating a dc output. Each one of these cells is a DC-DC converter operating as a Loss Free Resistor (LFR). In order to validate the concept a prototype has been built by the use of flyback converters operating in Discontinuous Conduction Mode (DCM). Furthermore, it operates in the full range of the European three-phase line voltage, which varies between 380V and 420V, and it supplies an output voltage of 48V with maximum power of 90 W ; Spanish Government under Project MINECO-13-DPI2013-47176-C2-2-R, the Principality of Asturias under the "Severo Ochoa" grant BP14-140 and the Project FC-15-GRUPIN14-143 and by the European Regional Development Fund (ERDF) grants

IEEE Applied Power Electronics Conference and Exposition, San Antonio, (Estados Unidos de Norteamérica), marzo de 2018 ; This work proposes the driving of high power Light-Emitting Diodes (LEDs) luminaires in three phase power grids using each phase to drive an independent LED load. The driving is done by means of a boost converter in charge of controlling the current across its LED load. Moreover, each boost converter needs to achieve Power Factor Correction (PFC) to comply with IEC 61000-3-2 Class C requirements. Hence, achieving unity Power Factor (PF) and low Total Harmonic Distortion (THD). Taking advantage of the light properties, the output of the LED driver will be the sum of the light of each of the phases. Therefore, a theoretical study will be carried out to observe the feasibility of removing the electrolytic capacitor while guaranteeing a flicker free behaviour of the LED luminaire, even if the current of each string is pulsating at twice the mains frequency. In order to validate the study, a prototype has been built comprised of three PFC boost converters disposing of their electrolytic capacitors. The designed prototype operates in the full range of the European three-phase line voltage, which varies between 380 V and 420 V, and it supplies an output light of 42.000 lm at a maximum power of 300 W while achieving an electrical efficiency of 97.5% ; This work was supported in part by the Spanish Government under Project MINECO-17-DPI2016-75760-R, in part by the Principality of Asturias under Severo Ochoa grant BP14-140, Project FC-15-GRUPIN14-143 and Project SV-PA-17-RIS3-4, and in part by European Regional Development Fund (ERDF) grants

The Asymmetrical Half Bridge converter (AHBC) has proven to be a promising candidate for LED lighting applications. It provides high efficiency, galvanic isolation and, at the same time, its output filter can be very small and, therefore, easily implemented without electrolytic capacitor. On the other hand, its main drawback is its poor attainable bandwidth. In any ac-dc LED lighting application, the input voltage of the AHBC is provided by a Power Factor Corrector (PFC) converter which has to be also implemented without electrolytic capacitor in order to assure the long lifetime of the whole LED driver. As a consequence, its output voltage (input voltage of the AHBC) is affected by a low-frequency ripple. Due to the poor bandwidth of the AHBC, this voltage ripple will be transferred to the converter output voltage, leading to flickering. A possible solution is using a feedforward loop for cancelling the effect of this low-frequency ripple without affecting stability. Due to the complex and non-linear transfer function of the AHBC, any analog feedforward loop has to be tuned for a given operating point, leading to a poor performance (i.e., high flickering, high ripple) when the AHBC moves away from that point. Dimming, which is a very frequent requirement in many LED drivers, implies large variations of the output voltage and, consequently, moving away from the aforementioned operating point. In this paper, a digital feedforward loop is proposed in order to solve this problem. The digital implementation allows the feedforward loop to perfectly cancel the ripple under any condition (e.g., output voltage variation due to dimming). Besides, despite its complex transfer function, this digital feedforward loop has been designed and optimized for its implementation in small-size microcontrollers. Experimental results with a 40-W prototype prove the usefulness of the proposed feedforward loop and the validity of the equations used in the optimized design ; This work has been supported by Spanish Government under ...