DC–DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc–dc converters, this paper aims to comprehensively review and classify various step-up dc–dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques.

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Step-Up DC–DC Converters: A Comprehensive Review of Voltage-Boosting Techniques, Topologies, and Applications

Based on a survey on over 1400 commercial LED drivers and a literature review, a range of LED driver topologies are classified according to their applications, power ratings, performance and their energy storage and regulatory requirements. Both passive and active LED drivers are included in the review and their advantages and disadvantages are discussed. This paper also presents an overall view on the technical and cost aspects of the LED technology, which is useful to both researchers and engineers in the lighting industry. Some general guidelines for selecting driver topologies are included to aid design engineers to make appropriate choices.

A Survey, Classification, and Critical Review of Light-Emitting Diode Drivers

Proportional-integral (PI) and sliding mode controls are combined to regulate a fourth-order Cuk converter in a continuous conduction mode. A closed-loop system is obtained with the aid of the equivalent control method. Based on the Routh-Hurwitz stability criterion and root locus, the appropriate PI gains are obtained and a stable and robust system suitable for large signal variations is achieved. The minimum or nonminimum phase behavior of the closed-loop system and the transients of the closed- loop system under step variations of various circuit parameters are analyzed. Under a wide range of operating points, the Cuk converter under the proposed controller has a load voltage tracking accuracy within ±0.05 V with a moderate maximum switching frequency of not greater than 100 KHz. The merits and demerits of the proposed controller are compared with some other controllers.

PI and Sliding Mode Control of a Cuk Converter

A novel, accurate, compact, and power-efficient lithium-ion (Li-Ion) battery charger designed to yield maximum capacity, cycle life, and therefore runtime is presented and experimentally verified. The proposed charger uses a diode to smoothly (i.e., continuously) transition between two high-gain linear feedback loops and control a single power MOS device, automatically charging the battery with constant current and then constant voltage. An adaptive power-efficient charging scheme in the form of a cascaded switching regulator supply ensures the voltage across the charging power-intensive pMOS remains low, thereby reducing its power losses and yielding up to 27% better overall power efficiency. An 83% power-efficient printed circuit board prototype was built and used to charge several Li-Ion batteries to within plusmn0.43% of their optimum full-charge voltage and therefore within a negligibly small fraction of their full capacity

Accurate, Compact, and Power-Efficient Li-Ion Battery Charger Circuit

LEDs must be externally driven by power sources to emit light. One problem associated with driving LEDs is its inherent nonlinear relation between the emission intensity and the forward current. Thus, the light output obtained from an LED is strongly dependent on the actual current waveforms employed to drive it. It is found that driving an LED with dc produces light output that surpasses all other techniques including the commonly used pulse-width modulation (PWM) technique. On the other hand, for dimming function, it is found that the PWM technique offers greater dimming flexibility in comparison to dc technique. In this paper, a generalized methodology for driving LEDs inheriting the features of both of these techniques is proposed. It employs a pulsating current switching between two discrete current levels, where the current levels and their durations can be concurrently varied for a more precise mapping of the driving conditions to the light output. The existing dc and PWM techniques can be viewed alternatively as being special cases of this more general approach.

On Driving Techniques for LEDs: Toward a Generalized Methodology

In recent years, light emitting diodes (LEDs) have become a viable alternative to conventional light sources. The LEDs are now approaching performance levels that make them attractive for use in several illumination applications. One of the main advantages of LEDs is their very long life that it is also related directly with the maintenance of the LED current, preventing the device overheating. To contribute with the advantages of the LEDs, the same ones need efficient drivers with optimized control circuitry. The main focus of this paper is to improve the LED driver characteristics using microcontrolled Cuk converter, therefore, greater durability and efficiency can be achieved and working for different nominal values of voltage, from an universal input voltage or battery. Mathematical analysis and experimental results are presented to the drive of an LED lamp of 11 W built with 10 power LEDs Creereg XLampreg XR-C.

A proposal of Led Lamp Driver for universal input using Cuk converter

Light emitting diodes (LEDs) have many features that make them attractive for use in an increasing number of applications. Particularly in lighting, the small size of LEDs compared to fluorescent and incandescent bulbs is a prominent advantage. This paper presents two topologies based on the buck converter, which have higher step-down characteristic than that of the original converter. The quadratic buck converter is studied and used to drive series-connected LEDs. Improved characteristics if compared with the traditional converter include the continuous current maintained through the LEDS and the possibility of driving several types of LED arrays. The study is then extended to the cubic buck converter, as a novel arrangement to obtain the mentioned step-down characteristic is introduced in this work. The use of such converter allows obtaining lower output voltages than those resulting from the quadratic buck converter. Experimental prototypes of the converters are implemented and fully tested. It must be also mentioned that a PIC microcontroller is used to control the current through the LED array, what provides robustness and flexibility in the adjust of the control algorithm without the need of hardware modification.

Non-isolated DC-DC converters with wide conversion range used to drive high-brightness LEDs

This paper presents a new proposal for driving LED lamps through the use of a micro controlled quadratic buck DC/DC converter The main focus is to improve the LED driver's characteristics using the microcontroller PIC16F873A, thus achieving greater durability and efficiency Mathematical analyses and experimental results are presented in this paper

Microcontroller-based quadratic buck converter used as led lamp driver

This paper presents a new topology of soft-switching two-switch forward converter associated to a quadratic boost converter, which provides large voltage step-up (from 12 V/sub dc/ to 80 V/sub dc/). The combination of the stages results in a switched-mode power supply (SMPS), whose output voltages are +200 V/sub dc/ and -200 V/sub dc/. The operation of both converters is analyzed, as some results concerning the proposed SMPS are presented.

Proposal of a switched mode power supply employing a quadratic boost converter and a new topology of soft-switched two-switch forward converter

An effective microcontrolled battery charger circuit that monitors the charging process avoiding the battery damage by overcharge is described, where a PWM forward topology with power factor correction is employed in order to provide DC/DC conversion. Depending on the battery charge state, which is determined by microcontroller PIC 16F873, the charging process is modified. In this way, fast charging does not have negative effects on the effective capacity of the battery and on battery cycle-life.

A.E. Demian

Papers

A proposal of Led Lamp Driver for universal input using Cuk converter

Non-isolated DC-DC converters with wide conversion range used to drive high-brightness LEDs

Microcontroller-based quadratic buck converter used as led lamp driver

Proposal of a switched mode power supply employing a quadratic boost converter and a new topology of soft-switched two-switch forward converter

A novel microprocessor-based battery charger circuit with power factor correction