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This article presents a two-stage automotive LED driver architecture delivering independently regulated output currents to multiple LED strings. The system consists of a multiphase noninverting buck–boost front-end stage, which allows for a wide battery voltage range, followed by high-frequency immittance-network-based LCL-T resonant converters, which operate as current sources over wide output voltage ranges. The two-stage buck–boost + resonant (BB+resonant) architecture takes advantage of the buck and boost capability of both stages, and the flexibility in setting the intermediate bus voltage to minimize losses. Advantages of the BB+resonant architecture include the use of lower voltage rated devices and soft switching in the resonant stage, leading to reduced losses and size. Experimental results are provided for a prototype consisting of a 250-kHz two-phase front-end stage and 2-MHz LCL-T resonant stages delivering independently regulated 1 A currents to four LED strings with $N = 1$ $-$ 18 LEDs. The measured system efficiency is greater than 88% over wide input (8 $-$ 18 V) and output (3–50 V) voltage ranges, with a peak efficiency of 93%.

In this article, a single‐stage bridgeless LLC resonant converter with a constant frequency control method is proposed for a high‐brightness light‐emitting diode (LED) driver. LED strings require drivers with high power density and high efficiency. This article presents a novel LED driver circuit topology based on switch integration and the switching controlled capacitor (SCC) technique. By combining the merits of a totem‐pole bridgeless boost PFC unit and a high frequency SCC‐LLC half‐bridge resonant converter, the proposed topology can achieve high efficiency. Due to the SCC‐LLC circuit topology structure, constant frequency control of the LLC resonant converter is achieved by the regulation of the equivalent resonant capacitance. The proposed novel LED driver topology can automatically achieve soft‐switching characteristics and a high power factor. The operating principle of different operation modes and the characteristics of the proposed LED driver are analysed in detail. Finally, to demonstrate the feature of the proposed topology, a 100 W/70 V laboratory prototype is built. The satisfactory experimental results correspond with the theoretical analysis and parameter design.

Purpose The purpose of this study is to design a more flexible and larger range of the dimming circuit that achieves the independence of multiple LED strings drive and can time-multiplex the power circuit. Design/methodology/approach The state-space method is used to model the BUCK circuit working in Pseudo continuous conduction mode, analyze the frequency characteristics of the system transfer function and design the compensation network. Build a simulation platform on the Orcad PSPICE platform and verify the function of the designed circuit through the simulation results. Use Altium Designer 16 to draw the printed circuit board, complete the welding of various components and use the oscilloscope, direct current (DC) power supply and a signal generator to verify the circuit function. Findings A prototype of the proposed LED driver is fabricated and tested. The measurement results show that the switching frequency can be increased to 1 MHz, Power inductance is 2.2 µH, which is smaller than current research. The dimming ratio can be set from 10% to 100%. The proposed LED driver can output more than 48 W and achieve a peak conversion efficiency of 91%. Originality/value The proposed LED driver adopts pulse width modulation (PWM) dimming at a lower dimming ratio and adopts DC dimming at a larger dimming ratio to realize switching PWM dimming to analog dimming. The control strategy can be more precise and have a wide range of dimming.

High brightness LEDs have become a mainstream lighting technology due to their efficiency, life span, and environmental benefits. As such, the lighting industry values LED drivers with low cost, small form factor, and long life span. Additional specifications that define a high quality LED driver are high efficiency, high power factor, wide-range dimming, minimal flicker, and a galvanically isolated output. The flyback LED driver is a popular topology that satisfies all these specifications, but it requires a bulky and costly flyback transformer. In addition, its passive methods for cancelling AC power ripple require electrolytic capacitors, which have been known to have life span issues. This dissertation details the design, construction, and verification of a novel LED driver that satisfies all the specifications. In addition, it does not require a flyback transformer or electrolytic capacitors, thus marking an improvement over the flyback driver on size, cost, and life span.This dissertation presents an integrated circuit (IC) LED driver, which features a pair of generalized multilevel converters that are controlled via sigma-delta modulation. The first is a multilevel rectifier responsible for power factor correction (PFC) and dimming. The PFC rectifier employs a second order sigma-delta loop to precisely control the input current harmonics and amplitude. The second is a bidirectional multilevel inverter used to cancel AC power ripple from the DC bus. This ripple-cancellation module transfers energy to and from a storage capacitor. It uses a first order sigma-delta loop with a preprogrammed waveform to swing the storage capacitor voltage. The system also contains an output stage that powers the LEDs with DC and provides for galvanic isolation. The output stage consists of an H-bridge stack that connects to the output through a small toroid transformer.The IC LED driver was simulated and prototyped on an ABCD silicon test chip. Testing and verification indicates functional performance for all the modules in the LED driver. The driver exhibits moderate efficiency at half voltage. Although the part was only testable to half voltage, loss models predict that its efficiency would be much higher at full voltage. The driver also meets specifications on the line current harmonics and ripple cancellation.This dissertation introduces multilevel circuit techniques to the IC and LED research space. The prototype's functional performance indicates that integrated multilevel converters are a viable topology for lighting and other similar applications.

A flicker-free resonant LED driver with high power factor (PF) and passive current balancing is proposed and analysed in this paper. The proposed LED driver are composed a buck power factor correction (PFC) unit and a resonant dc-dc unit by sharing an active switch. Based on this topology, the low output current ripple can be achieved via small voltage ripple on bulk capacitor and fast voltage-mode control loop. By the charge balance for resonant capacitor, the output current of each LED string can be balanced. In a half line cycle, owing to the small voltage ripple on bulk capacitor of pre-stage output, the duty cycle of active switch is almost constant. Therefore, when the inductor current of buck PFC unit operates in discontinuous conduction mode, high PF can be realized. Moreover, as the resonance is existed between resonant capacitor and leakage inductor of transformer, the diodes in resonant dc-dc unit can achieve zero-current turn-off. Thus, the efficiency can be improved. Finally, an 82W LED driver prototype with three-output is built to verify the studied results.

This paper proposes a high-performance isolated single-ended primary inductor converter (SEPIC) that is integrated with a non-dissipative snubber for a light-emitting diode (LED) driver. The proposed LED driver employs the snubber circuit to minimize any switching overvoltage caused by parasitic leakage inductance of the high-frequency transformer in the isolated SEPIC converter. This paper also presents a detail theoretical analysis of the proposed LED driver including its operating modes and design calculation. The experimental results of the proposed LED driver at the rated power of 18 W shows that it has a high-power factor, low harmonics, employs non-electrolytic capacitors, low switching stress, high reliability and high efficiency.

This paper introduces a megahertz-frequency resonant dc–dc converter that inherently achieves a load-independent output current while maintaining high efficiency across a wide output voltage range. These properties make the proposed converter well-suited for automotive light-emitting diode (LED) driver applications, where a varying number of LEDs need to be driven with a constant current. The proposed converter achieves load-independent output current by utilizing an LCL -T resonant network, and achieves high efficiency using a comprehensive design optimization methodology. This LCL -T resonant converter is also capable of regulating its output current at any desired value by utilizing phase-shift control. The performance of the LCL -T resonant converter is theoretically and experimentally compared with an LC 3 L and an LCLC resonant converter. For the experimental comparison, prototypes LCL -T, LC 3 L , and LCLC resonant converters are designed to operate at 2 MHz and across an output voltage range of 3.3–49.5 V while supplying a constant 0.5 A output current to the LEDs. The LCL -T resonant converter prototype achieves a peak efficiency of 91.1%, which is 0.6% and 1.8% higher than the peak efficiency of the LC 3 L and the LCLC converter prototypes, respectively. Furthermore, the LCL -T converter prototype maintains 0.8% and 1.6% higher average efficiency over its 15:1 output voltage range relative to the LC 3 L and the LCLC converter prototypes, respectively.

With the increase in technological advancements and impetus to work for the reduction of electrical energy consumption among different types of consumers, there is a primary need to take into account all forms of energy efficiency improvement methods available for electric and electronic equipment been used. It has been noticed that in commercial lighting, in terms of efficiency light-lamps based on light-emitting diodes(LEDs) are far better as compared to those where traditional high pressure sodium (HPS) lamps which are still in use in major underdeveloped and developing areas worldwide in specifically street lighting. The LED have numerous advantages such as high luminous efficiency, life span and it has no mercury in its composition. Therefore, recently researchers of this area has been setting a goal to utilize LED as a good alternative to save electricity from major parts of this planet. In this paper simulation of LED driver circuit is presented to utilize the 12 V LED lighting strip which has been used in Indian hawkers/small shopkeepers since a long time.

This paper proposes an efficient LED lamp converter circuit incorporating dimming feature and multiple lamp independent control. The converter consists of a half-bridge resonant converter in series...

International audience; The efficiency of electrical energy has become the most important elements in the part of electrical and electronic systems partially in the lighting systems, for this reason the light-emitting diode (LED) lamps are widely used in recent years. Nevertheless, LED is a non-linear load which causes a very high harmonic current, and a low power factor PF, thus a poor power quality. Research is focused on reducing current harmonics and improving the power factor (PF) has intensified. In this paper, a comparative study between Passive Power Factor Corrector (PPFC) with different topologies and Active Power Factor Corrector (APFC). These types were modeled using the LTspice software and the input power factor (PF) and total harmonic distortion (THD) of each type is determined and analyzed.

A buck-boost AC-DC light-emitting diode (LED) driver for a lamp with a visible light communication (VLC) module is proposed in this paper. In the proposed LED driver, a buck-boost power factor corr...

An efficient ripple-free light-emitting diode (LED) driver circuit is proposed with zero-voltage switching (ZVS) and dimming control. The proposed driver circuit utilizes a full-bridge configuratio...

LED lighting market share shows an ever increasing trend. This is driven by some of the LED advantages, such as higher efficiency, wide range of colors, and longer lifetime. LED is a DC device, and to power it from AC supply, like in household or street lightings, a driver is required to convert AC to DC supply. In addition, LED driver is preferred to operate in constant current mode in order to avoid LED thermal runaway. Also the driver has to have high efficiency, low THD (total harmonic distortion), and comply with electromagnetic emission limits. In this paper, a prototype of primary-side-regulated AC-DC flyback LED driver has been implemented. It has a constant output current of 0.990A 0.012A across the output voltage 15.59V – 42.80V. Measurement results show that the achieved efficiency is up to 88.55%, current harmonics comply with IEC 61000-3-2, and conducted emission levels comply with CISPR 15.

In this chapter, a survey of LED driver circuits is presented. The driver circuit is a crucial component in the LED light system. It provides the correct voltage and current values for the best brightness and long life. Furthermore, the driver circuits contribute to obtaining high efficiency and reliability light system. Several lighting applications need different driver topologies that meet the use requirement and the energy sources available. In actual applications, passive and active circuits are implemented to satisfy the LED driver electrical requirements and cost-effective demands. The LED driver circuits investigation evaluate the issues and the solutions in the LED lighting systems connected to a DC source such as a battery or AC line. The AC line connection requisites such as the power factor correction and the harmonic distortion are dealt with both the driver topology and control optimization. Also, the volume reduction need is examined in the circuitry choice. Moreover, the different topologies of the power converters isolated and not isolated used in the driver circuits based on both the power request and supply source are described and critically evaluated.

The main contribution of this paper is to show a new AC/DC converter based on the rearrangement of the flyback converter. The proposed circuit only manages part of the energy and the rest is delivered directly from the source to the load. Therefore, with the new topology, the efficiency is increased, and the stress of the components is reduced. The rearrangement consist of the secondary of the flyback is placed in parallel with the load, and this arrangement is connected in series with the primary side and the rectified voltage source. The re-arranged flyback is only a reductive topology and with no magnetic isolation. It was studied as a power supply for LEDs. A low frequency averaged analysis (LFAA) was used to determine the behavior of the proposed circuit and an equivalent circuit much easier to analyze was obtained. To validate the theoretical analysis, a design methodology was developed for the re-arranged flyback converter. The designed circuit was implemented in a 10 W prototype. Experimental results showed that the converter has a THDi = 21.7% and a PF = 0.9686.

In this paper, an LLC light-emitting diode (LLC LED) driver based on the current-sharing capacitor is presented. In the proposed LED driver, the LLC resonant converter is used to step down the high input voltage, to provide galvanic isolation, to offer a constant current for LEDs. Moreover, the current-sharing capacitor connected to the central-tapped point of the secondary-side winding is used to balance the currents in two LED strings. By doing so, the voltage stress on this capacitor is quite low. Above all, the equivalent forward voltages of the two LED strings are generally influenced by the temperature and the LED current, and this does not affect the current-sharing performance, as will be demonstrated by experiment on the difference in number of LEDs between the two LED strings. In addition, only the current in one LED string is sensed and controlled by negative feedback control, while the current in the other LED string is determined by the current-sharing capacitor. Moreover, this makes the current control so easy. Afterwards, the basic operating principles and analyses are given, particularly for how to derive the effective resistive load from the LED string. Eventually, some experimental results are provided to validate the effectiveness of the proposed LED driver.

In this paper output voltage modulated half-bridge series resonant converter (HBSRC) for LED driver application is proposed. In this converter HBSRC is cascaded with a buck-boost converter (BBC). The sum of output voltages of buck-boost converter and HBSRC drives the LED load. The LED current is controlled by regulating the buck-boost converter output voltage. Thus the HBSRC is working at firm frequency and duty ratio to achieve Zero voltage switching (ZVS) operation for input voltage variations. In this arrangement the BBC handles only fraction of the LED power, which doesn’t influence the overall efficiency of the converter much. The analysis of the proposed concept and a 26 Watt LED driver simulation results are presented.

In this paper, a stacked half bridge converter with automatic current balance and soft-switching is proposed. Here, an LED driver is taken as an example to analyze. Based on the ampere-second balance principle, the proposed LED driver can realize automatic current balance. The proposed converter adopts a small inductor to form a resonant tank, which achieves zero current switching (ZCS) in the discontinuous operation mode (DCM) and zero voltage switching (ZVS) in the continuous operation mode (CCM). By using frequency doubling technology, switching losses are reduced by half under the same hardware conditions. A 15.8W experimental prototype with 100V input voltage and 25V output voltage is established in the laboratory, verifying the feasibility of the stacked half bridge converter.

A LED (Light Emitting Diode) driver operating under a DC input voltage and driving a series of high power LEDs, is presented in this paper. Different topologies of LED driver feeding a constant current into a LED load and their operation principles are analyzed and discussed in detail. Then, a laboratory prototypes of constant-current LED drivers based on DC-DC buck converter with full dimming capability is designed, implemented, and tested. Experimental results show good agreement with simulation results.

Highly efficient passive Light Emitting Diode (LED) driver configurations are studied and examined in this paper. The technology based on the LED becomes a promising lighting technology to exchange inefficient energy lamps. For outdoor applications, the LED drivers based on passive elements are appropriate in extreme weather conditions. A comparison of LED driver configurations is presented. Each LED driver configuration is validated through simulation, and their waveform characteristics are examined and analyzed.

Due to the use of electrolytic capacitor, the life span and operating temperature range of traditional light emitting diode (LED) drivers are limited. In order to solve these problems, many researchers focus on electrolytic capacitor-less design. In this paper, a new electrolytic capacitor-less LED driver with power factor correction (PFC) function is proposed. By using a coupled inductor, a single-stage topology with optimized energy-flow-path and higher efficiency is proposed. With this new topology, electrolytic capacitor can be replaced by film capacitor with lower capacitance value and longer lifetime so that the life span of the LED driver can be prolonged. Simulation results are presented to verify the proposed design.

The trend of utilizing light emitting diodes (LEDs) in some applications has attracted the attention of many researchers, to study its applications. This article investigates the performance analysis of the dc–dc converter systems based on analog and digital controllers for a low voltage dc–dc buck converter, to drive strings of LEDs at different conditions, to judge system’s robust performances. This converter comprises of a single controller, working with a voltage control feedback system, in a continuous conduction mode. The analog and digital type-3 controllers are designed for the said system while using standard frequency response techniques. Simulations are shown to validate the design and the response of these controllers under various dynamic load conditions.

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

This paper presents the implementation of a two-stage light-emitting diode (LED) driver based on commercial integrated circuits (IC). The presented LED driver circuit topology, which is designed to drive a 150 W LED module, consists of two stages: AC-DC power factor correction (PFC) stage and DC/DC power converter stage. The implementation of the PFC stage uses IC NCP1608, which uses the critical conduction mode to guarantee a unity input power factor with a wide range of input voltages. The DC/DC power converter with soft-switching characteristics for the entire load range uses IC FLS2100XS. Furthermore, the design of an electromagnetic interference (EMI) filter for the LED driver and the dimming control circuit are discussed in detail. The hardware prototype, an LED lighting system, with a rated power of 150 W/32 V from a nominal 220 V/50 Hz AC voltage supply was tested to show the effectiveness of the design. The presented LED driver was tested for street lighting, and the experimental results show that the power factor (PF) was higher than 0.97, the total harmonics distortion (THD) was lower than 7%, and the efficiency was 91.7% at full load. The results prove that the performance of the presented LED driver complies with the standards: IEC61000-3-2 and CIRSP 15:2009.

This paper proposes a dual-frequency series resonant converter based LED driver which can drive two LED loads with independent control. In this converter one leg of the full bridge inverter operated at high frequency (HF) and the other leg of the inverter is operated at low frequency (LF). Two series resonant converters are connected across output of full-bridge inverter, which are tuned for HF and LF. The output voltages of LED loads are regulated independently by controlling duty cycle of respective legs of full-bridge inverter. To validate the proposed concept a 60 W (20W LF and 40 HF) LED driver is simulated in PSPICE and results are presented.

This paper presents a 7.7-mm2 on-chip LED driver based on a DC/DC resonant hybrid-switched capacitor converter operating in the MHz range with and without output capacitor. The converter operation allows continuously dimming the LED while keeping control on both peak and average current. Also, it features no flickering even in the absence of output capacitor and for light dimmed down to 10% of the nominal value. The capacitors and switches of the LED driver are integrated on a single IC die fabricated in a low-cost 5 V 0.18-μm bulk CMOS technology. This LED driver uses a small (0.7 mm2) inductor of 100 nH, which is 10 times smaller value than prior art integrated inductive LED drivers, still showing a competitive peak efficiency of 93% and achieving a power density of 0.26 W/mm2 (0.34 W/mm3).

This paper proposes a novel single-stage light-emitting diode (LED) driver with interleaved power-factor corrections (PFC) suitable for energy-saving streetlight applications. The presented circuit...

In order to reduce the size and cost of a medium-power light-emitting diode (LED) driver, a novel single-stage LED driver integrating a boost converter with a half-bridge LLC resonant converter has been proposed. This topology is composed of a boost power factor correction circuit operating in a discontinuous conduction mode and an isolated LLC circuit unit with soft-switching characteristics. The proposed LED driver only adopted two switch components, thus benefiting from control simple and without employing an extra switch driver and a control circuit. The operating principle and characteristics of the proposed LED driver are analyzed in detail. In addition, experimental results of a laboratory prototype for supplying a 100-W/70-V LED lighting systems from 220-V/50-Hz ac line voltage are presented to verify well the correctness of the theoretical analysis and parameters’ design.

Light emitting diodes (LEDs) are current driven devices. So, it is essential to maintain the stability of LED voltage and current. Variation of temperature may cause of instabilities and bifurcations in the LED driver. Driving LEDs from an offline power source faces design challenges like it have to maintain low harmonics in input current, to achieve high power factor, high efficiency and to maintain constant LED current and to ensure long lifetime. This paper proposes the technique of harmonics reduction by using parametric optimization of Single ended primary inductor converter (SEPIC) based LED driver. Without optimization of SEPIC parameters input energy will not be properly transferred to the load and this un-transferred energy will be transmitted to the source. Consequently, the quality of input current will be hampered i.e. harmonics will contaminate the input current. Focussing this, the paper has presented the design of a non-isolated integrated-stage single-switch constant current LED driver operating in discontinuous conduction mode (DCM) in SEPIC incorporating the design of control circuit with soft start mechanism. This LED driver has achieved a good efficiency (90.6%) and high-power factor (0.98) with reduced harmonics (3.35%). System stability has been determined and simulation studies are performed to confirm the validity of the LED driver circuit. A laboratory prototype is built to verify the functionality and performance of the proposed LED driver.

The reliability of a LED luminaire depends on the reliability of each of its subsystems. Experience suggests that, of these subsystems, it is the LED driver that tends to fail earliest. Any LED driver has an electrolytic capacitor to limit the ripple current, which helps the luminaire to function appropriately. This paper describes the effects on ripple current of changes in the capacitance and thus on LED luminaire performance. A capacitor bank is developed containing electrolytic capacitor combinations to obtain 27 capacitance values in the range 0.017 to 1570 µF. Two commercially available LED downlighter luminaires of the same model and manufacturer were used for this study. The ripple current and lumen output values are observed after connecting each capacitance from the bank, and the percentage flicker is calculated. LED light output shows visible flicker for low capacitances up to 0.1 µF with percentage flicker above 100%, while percentage flicker for capacitors up to 100 µF is more than 50%. For capacitance values of 220 µF and more, the percentage flicker is less than 50%. For the LED driver the capacitor decides the amount of ripple in the output current, so this work helps in formulating metrics for determining the service life of LED luminaires.

In this paper, a Double Frequency Buck Driver (DFBD) using SiC diodes for LED lighting systems is presented. This topology enhances the efficiency of the Double Frequency Buck Converter (DFBC) by minimizing the switching losses in power diode. The design procedure, mathematical equations and efficiency calculations of the DFBD are discussed. A prototype of the Conventional Buck Converter (CBC) with Si and SiC diode, DFBC with SiC diode and Si diode is implemented for 10W LED in hardware. Experimental results are presented for the four different topologies to imply that the efficiency of the system increases with SiC diodes. In addition, the cost analysis and energy savings for a multi-storeyed official building are estimated for the DFBC with SiC topology and validated with the other topologies.

LED is a promising new generation of green lighting with the advantages of high efficiency, good optical performance, long lifetime and environmental friendliness. A pulsating current can be used to drive LEDs. However, current with a high peak-to-average ratio is unfavorable for LEDs. A novel control scheme for the ac-dc critical conduction mode (CRM) flyback LED driver is proposed in this paper. By using the input voltage, output voltage and average output current to control the turn-on time of the switch, the peak-to-average ratio of the output current can be reduced. The operation principle is analyzed and an implementation circuit is put forward. Experimental results show the effectiveness of the proposed scheme.

A dimmable LED driver along with an extendable series structure and interleaved capacitive current sharing is presented herein, the LED connection of which is changed from the traditional series structure to the proposed parallel structure. The number of LED strings can be extended. As the number of LED strings is increased, the output voltage of this LED driver and the voltage stress on the main switch are ideally not influenced. Moreover, only one current sensor is needed to achieve current control and dimming. In this paper, the basic operating principle of the proposed LED driver is described and analyzed. Finally, the effectiveness of this LED driver is demonstrated by experiment based on the field-programmable gate array (FPGA).

This study indicates a converter based on change condenser to drive a high power light emitting diodes LEDs. Unlike standard steady current DC drivers, change condenser provides the current pulse. The recommended approach varies from the classical switch capacitor as it utilizes a little inductor to improve the swapping performance of the converter. The impact of condensers on the chosen regulator is demonstrated and examined based on the charging control analysis. A 3 W, 220 V experimental prototypes has been implemented when the outcomes are reported and explained in order to show that the proposed converter is practically feasible and can be used as LED driver.