The Effects of Spread-Spectrum Techniques in Mitigating Conducted EMI to LED Luminance

Rapid voltage and current changes in recently ubiquitous LED driver have a potency to interfere other devices. Solutions with special converter design, component design, EMI filter, and spread-spectrum techniques have been proposed. Due to cost-size-weight constraints, spread-spectrum technique seems a potential candidate in alleviating EMI problem in LED application. In this paper, the effectiveness of conducted EMI suppression performance of the spread-spectrum technique is evaluated. Spread-spectrum techniques applied by giving disturbance to the system LED driver with 3 profile signals, filtered square, triangular, and sine disturbance signal to the switching pattern of a buck LED driver. From the test results, 472.5 kHz triangular and 525 kHz sine signal can reduce EMI about 42 dBuV whilethe filtered square signal can reduce EMI 40.70 dBuV compare with fundamental constantfrequency reference 669 kHz. The average reduction in the power level of the third signal inthe frequency range of 199 kHz to 925 kHz for 5.154281 dBuV and the filtered square signal can reduce the average power level better than other signal disturbance of 5.852618 dBuV.LED luminance decrease when the spread-spectrum technique is applied to the system about 2814 lux

Power factor improvement on LED lamp driver using BIFRED converter

This paper presents the implementation of a power converter to improve power factor for LED lamp driver. The power converter which used in this system is the integration of boost and flyback converter (boost integrated flyback rectifier energy storage DC-DC/BIFRED). The boost converter as power factor correction (PFC) works on discontinuous conduction mode (DCM) operation to make the resistive converter. Thus, when a rectifier circuit supplies a resistive load, the load current that flows back to the source will have the same waveform as the voltage and it makes the power factor value next to 1 (unity). According to experiment results, the BIFRED converter as LED lamp driver can improve power factor from 0.84 to become 0.98 and this driver circuit also meets the line-current harmonic limits set by IEC61000-3-2 class C

Controladores LED eficientes para aplicações de iluminação geral

Mestrado em Engenharia Eletrónica e TelecomunicaçõesThe ever growing energy consumption trends and its impact on the environment has triggered worldwide attention. This has motivated several measures, such as the Kyoto protocol, or the 20 20 20 European strategy, aiming at the reduction of energy consumption. Globally, these measures defend a better and efficient usage of the available energy. This in turn is strongly linked to public awareness and the introduction of efficient electronic equipment. Public street lighting is a good example of these trends, where both aspects are of the utmost importance. The introduction of power LEDs as future lighting devices has motivated several advances coping with these strategies. On one side, LEDs are able to deliver higher efficiency when compared to conventional lighting devices. This has triggered the replacement of old style luminaires by LED based ones. However, their high cost has prevented full adoption and at the present stage, is acting as a slowing down force against this replacement trend. Better solutions are under research on the framework of several European projects. Power LEDs are solid-state devices able to support fast switching, a feature which was not fully supported by conventional lighting devices. Combining this feature with environmental sensing and intelligent control may lead to better power savings. A simple approach would be to consider the that the actual lighting demands depend on the street usage and surrounding lighting levels. For this purpose, the combination of twilight sensors, motion detectors and intelligent control schemes may provide a suitable approach. This way, the real lighting demands can be effectively taken into consideration, providing luminaires able to consume the least possible energy. For this to become a reality several challenges have to be addressed. One of the most important challenges is the LED driver design. Modern lighting systems based on LEDs, replace the traditional ballasts by LED drivers. When efficiency is a major concern, such as in public street lighting, these drivers have to be designed in order to be the most robust and efficient as possible. Recurring solutions resort to switched mode power supplies, able to support light dimming. One of the major problems with these drivers is the fact that their efficiency decreases for lower dimming levels. This is of the utmost importance for public street lighting, as most of the time during night, the luminaires are on a low lighting level (as changes to high lighting conditions depend on street usage). Thus, in order to promote better power savings, the efficiency of the driver should be high for both lighting conditions. Commercially available drivers, exhibit efficiencies on the 90% range for the high lighting conditions, with only 40% to 60% under the low lighting. On the framework of this master dissertation it was investigated the problem of LED driver design aiming at the highest possible uniformity of the efficiency curve, under different loading and dimming conditions. The selected approach was based on quasi-resonant flyback converter, backed up by an active power factor correcting block. The designed driver supports remote configuration and monitoring as well as sensor integration. The archived results show that this driver achieves a peak efficiency of 93% under maximum load and 100% duty-cycle. The efficiency for low dimming conditions (10% duty-cycle) achieves 75%.As tendências de consumo de energia cada vez maior e seu impacto sobre o meio ambiente tem captado a atenção a nível mundial. Isso tem motivado várias medidas, tais como o Protocolo de Quioto, ou a estratégia Europeia 20 20 20, visando a redução do consumo de energia. Globalmente, estas medidas defendem um uso melhor e eficiente da energia disponível. Este, por sua vez, está fortemente ligado à consciência pública e à introdução de equipamento eletrónico eficiente. A iluminação pública é um bom exemplo dessas tendências, em que ambos os aspetos são de extrema importância. A introdução de LEDs como dispositivos de iluminação tem motivado vários avanços que lidam com essas estratégias. De um lado, os LEDs são capazes de oferecer uma maior eficiência quando comparados com dispositivos de iluminação convencionais. Isso provocou a substituição de luminárias convencionais por luminárias baseadas em LED. No entanto, o custo elevado destes dispositivos tem impedido a adoção plena e na fase atual, está mesmo a atuar como uma força negativa contra esta tendência de substituição. Melhores soluções estão sob investigação no âmbito de vários projetos europeus. Os LEDs são dispositivos de estado sólido, capazes de suportar a comutação rápida, uma característica que não é totalmente suportada por dispositivos de iluminação convencionais. Combinando esta característica com sensores ambientais e controlo inteligente pode-se ambicionar melhores poupanças energéticas. Uma abordagem simples seria a de considerar o que as exigências de iluminação reais dependem do uso das ruas e os níveis de iluminação circundantes. Para este efeito, a combinação de sensores de crepúsculo, detetores de movimento e regimes de controlo inteligentes podem propiciar uma abordagem adequada. Desta forma, os requisitos reais de iluminação podem ser efetivamente considerados, fornecendo luminárias capazes de consumir apenas a energia necessária. Para que isto se torne uma realidade vários desafios têm de ser vencidos. Um dos desafios mais importantes é o projeto LED driver. Nos sistemas de iluminação modernos baseados em LEDs, substitui-se os balastros convencionais por LED drivers. Quando a eficiência é importante, como no caso da iluminação pública, O LED driver têm de ser concebido de forma a ser o mais robusto e eficiente possível. Soluções recorrentes usam a fontes de alimentação comutadas, capazes de suportar o escurecimento adaptativo do fluxo luminoso. Um dos problemas principais no projeto destes drivers é o facto de a sua eficiência diminuir para níveis de regulação mais baixos. Isto é de extrema importância para a iluminação pública, pois na maioria dos casos durante a noite, as luminárias estão num nível de iluminação de baixo. Assim, com a finalidade de promover uma melhor economia de energia, a eficiência do driver deve ser elevada para ambas as condições de iluminação. Drivers comercialmente disponíveis, exibem eficácias na gama de 90% com elevado fluxo luminoso, e apenas 40% a 60% na condição de baixo fluxo luminoso. No âmbito desta dissertação de mestrado foi investigado o problema do projeto de driver LED visando a maior uniformidade possível da curva de eficiência, sob diferentes condições de carga e de fluxo luminoso. A abordagem escolhida foi baseada no conversor flyback quasi-ressonante, apoiado por um bloco de correção de fator de potência ativa. O driver projetado suporta configuração e monitorização remota, bem como de integração de sensores. Os resultados alcançados mostram que este driver atinge um pico de eficiência de 93% na condição de carga máxima e máximo fluxo luminoso. A eficiência em condições de baixo fluxo luminoso é superior a 75%

Multiple-output DC–DC converters: applications and solutions

Multiple-output DC–DC converters are essential in a multitude of applications where different DC output voltages are required. The interest and importance of this type of multiport configuration is also reflected in that many electronics manufacturers currently develop integrated solutions. Traditionally, the different output voltages required are obtained by means of a transformer with several windings, which are in addition to providing electrical isolation. However, the current trend in the development of multiple-output DC–DC converters follows general aspects, such as low losses, high-power density, and high efficiency, as well as the development of new architectures and control strategies. Certainly, simple structures with a reduced number of components and power switches will be one of the new trends, especially to reduce the size. In this sense, the incorporation of devices with a Wide Band Gap (WBG), particularly Gallium Nitride (GaN) and Silicon Carbide (SiC), will establish future trends, advantages, and disadvantages in the development and applications of multiple-output DC–DC converters. In this paper, we present a review of the most important topics related to multiple-output DC–DC converters based on their main topologies and configurations, applications, solutions, and trends. A wide variety of configurations and topologies of multiple-output DC–DC converters are shown (more than 30), isolated and non-isolated, single and multiple switches, and based on soft and hard switching techniques, which are used in many different applications and solutions.info:eu-repo/semantics/publishedVersio

Light-emitting diode driver for lighting application using field programmable gate array

Light-emitting diode (LED) is the most popular lighting source since the early 21st century. Its advantages include high efficiency, long lifetime and environmental friendliness makes it attractive in lighting application. This leads to the development of high energy efficient LED drivers. Despite the advantages, driving LEDs at high output ripple and without current regulation can degrade LEDs’ performance. Furthermore, energy consumption of the controller on LED driver contributes to energy loss. Moreover, prototyping a full custom application specific integrated circuit (ASIC) is time consuming and not reprogrammable. The main objective of this research is to design an LED driver for lighting application using field programmable gate array (FPGA), and to analyse the performance. Simulation model was developed and simulated in LTSpice IV software. The LED driver controller was developed using Altera DE0-Nano FPGA Board with Quartus II software using Verilog hardware description language. The power stage schematic and printed circuit board layout were designed using Cadsoft EAGLE software. The LED driver performance was assessed in term of energy efficiency and output ripple. In energy efficiency experiment, rheostat was used as load. The result shows that the simulation model and the hardware prototype achieved energy efficiency of 93.36% and 93.19% respectively. In output ripple experiment, the result shows that the maximum output ripple of the simulation model is 0.046% while the hardware prototype is 0.06%. High-brightness white LEDs was also used as load in assessing the LED driver energy efficiency. The result shows that the hardware prototype achieved energy efficiency of 93.18% and has a maximum output ripple of 0.054% when high-brightness white LEDs are used as load

Perancangan Filter EMI Pasif dalam Rangka Mitigasi Conducted emission pada Lampu LED

Light-emitting diode (LED) lamps become popular in a variety of applications, due to low power usage, high efficiency, and low maintenance. Another advantage of LEDs is that they are durable and environmentally friendly because they contain less toxic substance composition compared to other types of lamps. To achieve high efficiency in energy transfer to the LED power supply, a switching mode power supply (SMPS) is applied. SMPS was implemented with pulse width modulation (PWM) which operates at a constant frequency, producing significant emissions in several frequencies through conducted and radiated mechanisms. These emissions are called electromagnetic interference (EMI). As a result, many LED lamps have the potential to fail to meet the electromagnetic compatibility (EMC) standard. In this research, the design and implementation of passive EMI filters were carried out to reduce the conducted emission of LED lights on the market. Passive EMI filters are LC low pass filters (LPF). Before the LED lights were applied to the EMI passive filter, conducted emissions were measured to exceed CISPR 22 class B regulatory standards, which reached 82.5 dBµV. When the passive EMI filter was implemented, the LED lights occur conducted emission reduction in the frequency range 150kHz - 1.5MHz with an average value of 36.96 dBµV and a maximum reduction value of 34.7 dBµV.Lampu light emitting diode (LED) populer digunakan dalam berbagai macam aplikasi, karena penggunaan daya yang rendah, efisiensi yang tinggi dan perawatan yang rendah. Keuntungan LED lainnya adalah awet dan ramah lingkungan karena lebih sedikit mengandung komposisi zat beracun jika dibandingkan dengan jenis lampu lain. Untuk mencapai efisiensi yang tinggi dalam transfer energi pada catu daya LED, diterapkan topologi switched mode power supply (SMPS). SMPS diimplementasikan dengan pulse width modulation (PWM) yang beroperasi pada frekuensi konstan, menghasilkan emisi yang signifikan disejumlah frekuensi melalui mekanisme conducted dan radiated, emisi ini dinamakan electromagnetic interference (EMI). Sebagai akibatnya, banyak lampu LED berpotensi tidak bisa memenuhi standar electromagnetic compatibility (EMC). Pada penelitian ini dilakukan perancangan dan implementasi filter EMI pasif untuk meredam conducted emission pada lampu LED yang ada dipasaran. Filter EMI pasif berupa low pass filter (LPF).  Sebelum lampu LED diterapkan filter pasif EMI, conducted emission yang terukur melebihi standar regulasi CISPR 22 class B, nilai emisi tertinggi mencapai 82,5 dBµV pada frekuensi 299,25 kHz atau melebihi standar CISPR sebesar 30,9 dBµV. Saat filter pasif EMI dipasang lampu LED terjadi reduksi conducted emission pada rentang frekuensi 150kHz – 1,65MHz dengan nilai rata–rata sebesar 23,3 dBµV dan nilai reduksi maksimal sebesar 34,7 dBµV

Printed Electronics Power Supply for IoT Systems

CeNTI - Center for Nanotechnology and Smart Materials is an institute of R&D located in Famalicão. The main goal of the institute is to promote activities of research, Technological Development, Innovation and Engineering with special focus in smart materials and systems. The Internet Of Things is the concept by which multiple devices, are connected and performing activities with each other, such as communication and processing, without human interference. The development of multiple technologies such Artificial Intelligence, Machine Learning, Smart homes, smart devices has accelerated the convergence of all into networks. These networks at the edge of the system possess devices that are meant to make the connection between cyber environments and physical ones. This type of devices are often referred to as Edge devices. Devices like these are most often low power devices used to sense aspects of the physical system and their dimension might be a defining factor to decide if such system is adequate to its function. In sensors the most common forms of power supplies are batteries, mains electricity with a transformer for voltage division and isolation or a combination of both. With the increasing need for miniaturization and technological means to achieve it, the investigation of novel forms becomes more and more relevant. The main objective of this thesis is to investigate the use of printed electronics and in particular printed inductors, to attain an efficient and safe power supply adequate for human handling while aiming to reduce the final volume of the system. The approach intents to use the traditional Transformerless Power Supply circuit configuration using capacitors to drop the mains voltage. Such goal is to prevent undesired power expenditure caused by the introduction of resistances. Besides the voltage drop and rectification the other major concern of the system is the safety of the human operator that may touch the device. Voltage dropping and rectification of grid power is an extremely dangerous circuit configuration due to different ground references and creates an electrocution hazard to both living beings and devices connected to it. The way to circumvent the danger is to introduce galvanic isolation. The system proposed in this project physically separates the output of the system from the input with energy being transferred magnetically. For that purpose, printed inductors are stacked to achieve a planar air-core transformer. The system aims contributes to the continued minimizing of Edge devices that will become progressively more present in everyday life.In recent times, connected devices are becoming increasingly more common. Such devices usually referred to as IoT (Internet of Things), are converging to ever small builds. This document aims to deepen the progress in the field of miniaturization of such devices. To achieve this goal a power supply is designed. The project intents to offer an alternative to common power supplies by making use of printed inductors. Such components intent to replace the traditional transformer by suppling a reduced volume alternative. An investigation into these inductors is conducted and an implementation of its use is presented. The investigation led to conclude that the inductors may be used to provide isolation but further improvements into the fabrication process are required. Due to the current fabrication process involving impure silver as the conductor the resulting coils have a resistance excessively high. This creates difficulties in magnetic field creation as well as introducing a great level of losses. To solve this problem the presented implementation uses high frequency switching to allows for better results in the receiver side of the system

Large step down voltage converters for desalination

One percent of the world's drinking water is currently desalinated, and this will have to increase to 14% by 2025. Desalination is energy intensive, having significant commercial and ecological implications. One of the most promising methods of desalination is capacitive deionisation which only uses 1kWh/m3 but requires a voltage of less than 1.8V at currents of up to 1000A This thesis produced hardware capable of creating 550A at a voltage of 1.8V, giving over a 1kW power rating, with an input voltage of 340V dc. The converter designed was a bidirectional asymmetrical half-bridge flyback converter allowing for isolation at these high step down ratios. The converter was used to charge a bank of 17,000F supercapacitors from 0V to 1.8V, with an initial charging step down ratio in excess of 340:1 falling to 190:1 as the load charged. A novel Asymmetrical Half-Bridge Coupled-Inductor Buck converter is presented as the ideal solution for large step-down ratios with analysis comparing the ability to efficiently step down a voltage with other common converters, the buck and flyback converters. A comparison between a single-ended coupled-inductor buck converter employing a buck-boost voltage clamp and the novel asymmetrical half-bridge coupled-inductor buck converter circuit shows that the asymmetrical half-bridge converter is a more efficient circuit as leakage energy is recovered; the switch voltages are clamped to within the dc voltage rating of the bridge and the control strategy is simple. Passive and active snubbers are reviewed for efficiency, switch ratings and management of the effects of leakage inductance and compared against the novel designs presented. In the desalination application isolation is required so the flyback circuit is used. An isolated three switch bidirectional converter is constructed using silicon carbide MOSFETs and diodes switching at 40kHz. The converter uses novel current measuring techniques, an on-board microprocessor and closed loop control designed into the final DC-DC converter.One percent of the world's drinking water is currently desalinated, and this will have to increase to 14% by 2025. Desalination is energy intensive, having significant commercial and ecological implications. One of the most promising methods of desalination is capacitive deionisation which only uses 1kWh/m3 but requires a voltage of less than 1.8V at currents of up to 1000A This thesis produced hardware capable of creating 550A at a voltage of 1.8V, giving over a 1kW power rating, with an input voltage of 340V dc. The converter designed was a bidirectional asymmetrical half-bridge flyback converter allowing for isolation at these high step down ratios. The converter was used to charge a bank of 17,000F supercapacitors from 0V to 1.8V, with an initial charging step down ratio in excess of 340:1 falling to 190:1 as the load charged. A novel Asymmetrical Half-Bridge Coupled-Inductor Buck converter is presented as the ideal solution for large step-down ratios with analysis comparing the ability to efficiently step down a voltage with other common converters, the buck and flyback converters. A comparison between a single-ended coupled-inductor buck converter employing a buck-boost voltage clamp and the novel asymmetrical half-bridge coupled-inductor buck converter circuit shows that the asymmetrical half-bridge converter is a more efficient circuit as leakage energy is recovered; the switch voltages are clamped to within the dc voltage rating of the bridge and the control strategy is simple. Passive and active snubbers are reviewed for efficiency, switch ratings and management of the effects of leakage inductance and compared against the novel designs presented. In the desalination application isolation is required so the flyback circuit is used. An isolated three switch bidirectional converter is constructed using silicon carbide MOSFETs and diodes switching at 40kHz. The converter uses novel current measuring techniques, an on-board microprocessor and closed loop control designed into the final DC-DC converter