A Single-Stage LED Driver Based on ZCDS Class-E Current-Driven Rectifier as a PFC for Street-Lighting Applications

This paper presents a light-emitting diode (LED) driver for street-lighting applications that uses a resonant rectifier as a power-factor corrector (PFC). The PFC semistage is based on a zero-current and zero-derivative-switching (ZCDS) Class-E current-driven rectifier, and the LED driver semistage is based on a zero-voltage-switching (ZVS) Class-D LLC resonant converter that is integrated into a single-stage topology. To increase the conduction angle of the bridge-rectifier diodes current and to decrease the current harmonics that are injected in the utility line, the ZCDS Class-E rectifier is placed between the bridge-rectifier and a dc-link capacitor. The ZCDS Class-E rectifieris driven by a high-frequency current source, which is obtained from a square-wave output voltage of the ZVS Class-D LLC resonant converter using a matching network. Additionally, the proposed converter has a soft-switching characteristic that reduces switching losses and switching noise. A prototype for a 150-W LED street light has been developed and tested to evaluate the performance of the proposed approach. The proposed LED driver had a high efficiency (>91%), a high PF (>0.99), and a low total harmonic distortion (THD i <; 8%) under variation of the utility-line input voltage from 180 to 250 V rms . These experimental results demonstrate the feasibility of the proposed LED scheme

Single-Stage Led Drivers Based On Integrated Bcm Boost And Llc Converters For Street Lighting

Electrical lighting has been an important technology to modern society. Given the increasing concerns about environmental and energy saving issues, light-emitting-diode (LED) has become the research focus due to the features of mercury elimination and high energy efficiency compared to conventional lamps. Performance aspects of LED lighting are related with LED driver, thus an appropriate converter should be designed to power up the LEDs with good input power factor and high efficiency. To achieve these elements, single-stage alternating current to direct current (AC-DC) converter with power factor correction (PFC) is proposed as LED driver for application in street lighting. In this topology, a pair of boost circuits which share a single inductor are combined as a PFC stage and then integrated with half-bridge LLC resonant converter. Three kinds of rectifier circuits are proposed for the secondary-side rectification; full-wave bridge rectifier, full-wave voltage doubler rectifier and dual half-wave rectifiers. All rectifier circuits have their own advantages and remove the requirement of center-tapped transformer in circuit design. The power switches are driven by a high-voltage resonant controller IC L6598 with nearly 0.5 duty cycle and a small dead time. All proposed LED drivers have been tested in the laboratory for supplying 12 high-power LEDs from ac input voltage of 240-V. From the comparison results, LED driver using full-wave voltage doubler rectifier has shown the best performances, followed by LED driver using full-wave bridge rectifier and then LED driver using dual half-wave rectifiers. The highest power factor measured is almost unity at 0.99, the lowest total harmonic distortion (THD) is 13.8%, the highest efficiency is 93.39% and the lowest bus voltage is 330-V. The power factor correction was successfully achieved and high conversion efficiency was obtained due to soft-switching characteristics of the LED driver. The voltage stress on bus capacitor is considerably reduced to 1.36 times of the input-peak-voltage. The dimming capability was also accomplished. Lastly, the minimization of storage capacitance was successful with an acceptable range of output current ripple for flicker-less LED lighting

Overview of Passive Light Emitting Diode Driver Circuits for Street Lighting

This paper describes the overview and comparison of various passive Light Emitting Diode (LED) driver circuits employed for street lighting applications. Passive LED driver circuits are constructed with diodes and capacitors without using any power electronic semiconductor switches which in turn eliminates the secondary supply unit for control circuits and controllers. Passive LED driver circuits are simple in construction, low cost, less maintenance and control free. 50 W LED driver circuit is identified for performance comparison and simulations are performed in matlab- simulink to get an overview of different passive LED driver circuits. The most predominant parameters such as efficiency and total harmonic distortion are compared to identify the suitiblity of the driver circuits for various applications

Multiple Output Power Supply using Toroidal Transformers for Medium Voltage Active Gate Drivers

When operating in high power applications, power devices dissipate tens or hundreds of watts of power in the form of heat. The ability of the power devices to withstand power and dissipation of heat across the power devices becomes a prominent requirement in designing the power converter. This challenge demands a power converter design to be more effective and consistent which factors in size, cost, weight, power density and reliability. This study aims to propose a gate driver isolated power supply design that can be used in medium voltage applications (e.g., up to 10 kV) while respecting the principle of scalability. A versatile design that facilitates addition of another power switch to the converter if needed, without having to alter too many power supply components while retaining the main structure, thus reducing system complexity and size. The proposed topology is a full-bridge converter with a single-turn primary side transformer, realized using a high voltage insulated hook-up wire as primary winding, while the secondary winding is wound around a toroidal core. This structure can supply several gate drivers simultaneously without replicating the primary side converter, but by simply adding a toroidal core with the secondary side converter which effectively reduces the size of the power supply. To satisfy magnetic and electric constraints, the proposed toroidal transformer needs to exhibit a very low primary to secondary coupling capacitance to avoid high common mode current, which leads to control signal distortion. For this, a multi-objective optimization design has been performed for the magnetic components of the topology. In this paper, a single input and three output power supply design is proposed for a 10 kV active gate driver

Multiple Output Power Supply using Toroidal Transformers for Medium Voltage Active Gate Drivers

When operating in high power applications, power devices dissipate tens or hundreds of watts of power in the form of heat. The ability of the power devices to withstand power and dissipation of heat across the power devices becomes a prominent requirement in designing the power converter. This challenge demands a power converter design to be more effective and consistent which factors in size, cost, weight, power density and reliability. This study aims to propose a gate driver isolated power supply design that can be used in medium voltage applications (e.g., up to 10 kV) while respecting the principle of scalability. A versatile design that facilitates addition of another power switch to the converter if needed, without having to alter too many power supply components while retaining the main structure, thus reducing system complexity and size. The proposed topology is a full-bridge converter with a single-turn primary side transformer, realized using a high voltage insulated hook-up wire as primary winding, while the secondary winding is wound around a toroidal core. This structure can supply several gate drivers simultaneously without replicating the primary side converter, but by simply adding a toroidal core with the secondary side converter which effectively reduces the size of the power supply. To satisfy magnetic and electric constraints, the proposed toroidal transformer needs to exhibit a very low primary to secondary coupling capacitance to avoid high common mode current, which leads to control signal distortion. For this, a multi-objective optimization design has been performed for the magnetic components of the topology. In this paper, a single input and three output power supply design is proposed for a 10 kV active gate driver

Overview of Passive Light Emitting Diode Driver Circuits for Street Lighting

This paper describes the overview and comparison of various passive Light Emitting Diode (LED) driver circuits employed for street lighting applications. Passive LED driver circuits are constructed with diodes and capacitors without using any power electronic semiconductor switches which in turn eliminates the secondary supply unit for control circuits and controllers. Passive LED driver circuits are simple in construction, low cost, less maintenance and control free. 50 W LED driver circuit is identified for performance comparison and simulations are performed in matlab- simulink to get an overview of different passive LED driver circuits. The most predominant parameters such as efficiency and total harmonic distortion are compared to identify the suitiblity of the driver circuits for various applications

A review and classification of LED ballasts

This paper presents a review on existing ballasts for light-emitting diodes (LED) with considerations to their compliance to regulations, technological challenges, and on meeting various application requirements. All existing LED ballasts, including those proposed in recent literature, have been appropriately classified and systematically organized for the discussion. The dissemination of this information and its understanding is helpful for future R&D pursuits in this area. © 2013 IEEE.published_or_final_versio

Novel Offline Switched Mode Power Supplies for Solid State Lighting Applications

In recent years, high brightness light emitting diodes (HBLEDs) have increasingly attracted the interest of both industrial manufacturers and academic research community. Among the several aspects that make LED technology so attractive, the most appreciated characteristics are related to their robustness, high efficiency, small size, easy dimming capability, long lifetime, very short switch-on/switch-off times and mercury free manufacturing. Even if all such qualities would seem to give to solid state lighting a clear advantage over all the other kinds of competing technologies, the issues deriving from the need of LED technology improvement, on one hand, and of the development of suitable electronic ballasts to properly drive such solid state light sources, on the other, have so far hindered the expected practical applications. The latter problem, in particular, is nowadays considered the main bottleneck in view of a widespread diffusion of solid state technology in the general lighting market, as a suitable replacement of the still dominant solutions, namely halogen and fluorescent lamps. In fact, if it is true that some aspects of the devices’ technology (e.g. temperature dependent performance, light quality, efficiency droop, high price per lumen, etc…) still need further improvements, it is now generally recognized that one of the key requirements, for a large scale spread of solid state lighting, is the optimization of the driver. In particular, the most important specifications for a LED lamp ballast are: high reliability and efficiency, high power factor, output current regulation, dimming capability, low cost and volume minimization (especially in domestic general lighting applications). From this standpoint, the main goal is, therefore, to find out simple switched mode power converter topologies, characterized by reduced component count and low current/voltage stresses, that avoid the use of short lifetime devices like electrolytic capacitors. Moreover, if compactness is a major issue, also soft switching capability becomes mandatory, in order to enable volume minimization of the reactive components by increasing the switching frequency in the range of the hundreds of kHz without significantly affecting converter’s efficiency. It is worth mentioning that, in order to optimize HBLED operation, also other matters, like the lamp thermal management concern, should be properly addressed in order to minimize the stress suffered by the light emitting devices and, consequently, the deterioration of the light quality and of the expected lamp lifetime. However, being this work focused on the issues related to the research of innovative driving solutions, the aforementioned thermal management problems, as also all the topics related to the improvement of solid state devices’ technology, will be left aside. The main goal of the work presented in this thesis is, indeed, to find out, analyze and optimize new suitable topologies, capable of matching the previously described specifications and also of successfully facing the many challenges dictated by the future of general lighting. First of all, a general overview of solid state lighting features, of the state of the art of lighting market and of the main LED driving issues will be provided. After this first introduction, the offline driving concern will be extensively discussed and different ways of approaching the problem, depending on the specific application considered, will be described. The first kind of approach investigated is based on the use of a simple structure relying on a single power conversion stage, capable of concurrently ensuring: compliance with the standards limiting the input current harmonics, regulation of the load current and also galvanic isolation. The constraints deriving from the need to fulfil the EN 61000-3-2 harmonics standard requirements, when using such kind of solution for low power (<15W) LED driving purposes, will be extensively discussed. A low cost, low component count, high switching frequency converter, based on the asymmetrical half bridge flyback topology, has been studied, developed and optimized. The simplicity and high compactness, characterizing this solution, make it a very good option for CFL and bulb replacement applications, in which volume minimization is mandatory in order to reach the goal of placing the whole driving circuitry in the standard E27 sockets. The analysis performed will be presented, together with the design procedure, the simulation outcomes and the different control and optimization techniques that were studied, implemented and tested on the converter's laboratory prototype. Another interesting approach, that will be considered, is based on the use of integrated topologies in which two different power conversion stages are merged by sharing the same power switch and control circuitry. In the resulting converter, power factor correction and LED current regulation are thus performed by two combined semi-stages in which both the input power and the output current have to be managed by the same shared switch. Compared with a conventional two-stages configuration, lower circuit complexity and cost, reduced component count and higher compactness can be achieved through integration, at cost of increased stress levels on the power switch and of losing a degree of freedom in converter design. Galvanic isolation can be provided or not depending on the topologies selected for integration. If non-isolated topologies are considered for both semi-stages, the user safety has to be guaranteed by assuring mechanical isolation throughout the LED lamp case. The issue, deriving from the need of smoothing the pulsating power absorbed from the line while avoiding the use of short lifetime electrolytic capacitors, will be addressed. A set of integrated topologies, used as HBLED lamp power supplies, will be investigated and a generalized analysis will be presented. Their input line voltage ripple attenuation capability will be examined and a general design procedure will be described. Moreover, a novel integrated solution, based on the use of a double buck converter, for an about 15W rated down-lighting application will be presented. The analysis performed, together with converter design and power factor correction concerns will be carefully discussed and the main outcomes of the tests performed at simulation level will be provided. The last kind of approach to be discussed is based on a multi-stage structure that results to be a suitable option for medium power applications, like street lighting, in which compactness is not a major concern. By adopting such kind of solution it is, indeed, possible to optimize converter’s behavior both on line and on load side, thereby guaranteeing both an effective power factor correction at the input and proper current regulation and dimming capability at the output. Galvanic isolation can be provided either by the input or the output stage, resulting in a standard two stage configuration, or by an additional intermediate isolated DC-DC stage (operating in open loop with a constant input/output voltage conversion ratio) that namely turns the AC/DC converter topology into a three stage configuration. The efficiency issue, deriving from the need of multiple energy processing along the path between the utility grid and the LED load, can be effectively addressed thanks to the high flexibility guaranteed by this structure that, relaxing the design constraint, allows to easily optimize each stage. A 150W nominal power rated ballast for street solid state lighting applications, based on the latter (three stage) topology, has been investigated. The analysis performed, the design procedure and the simulations outcomes will be carefully described, as well as the experimental results of the tests made on the implemented laboratory prototype

A simplified controller and detailed dynamics of constant off-time peak current control

A fast and reliable current control is often the base of power electronic converters. The traditional constant frequency peak control is unstable above 50 % duty ratio. In contrast, the constant off-time peak current control (COTCC) is unconditionally stable and fast, so it is worth analyzing it. Another feature of the COTCC is that one can combine a current control together with a current protection. The time dynamics show a zero-transient response, even when the inductor changes in a wide range. It can also be modeled as a special transfer function for all frequencies. The article shows also that it can be implemented in a simple analog circuit using a wide temperature range IC, such as the LM2903, which is compatible with PV conversion and automotive temperature range. Experiments are done using a 3 kW step-up converter. A drawback is still that the principle does not easily fit in usual digital controllers up to now

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