J.B. Vieira

An improved boost PWM soft-single-switched converter with low voltage and current stresses

This paper presents an improved regenerative soft turn-on and turn-off snubber applied to a boost pulsewidth-modulated (PWM) converter. The boost soft-single-switched converter proposed, which has only a single active switch, is able to operate with soft switching in a PWM way without high voltage and current stresses. This is achieved by using an auxiliary inductor, which is magnetically coupled with the main inductor of the converter. In order to illustrate the operating principle of this new converter, a detailed study, including simulations as well as experimental results, is carried out. The validity of this new converter is guaranteed by the obtained results.

A State Equation Model of a Single-Phase Grid-Connected Inverter Using a Droop Control Scheme With Extra Phase Shift Control Action

This paper presents a state equation model of a single-phase pulsewidth modulation inverter connected to the grid, using frequency-active power and voltage-reactive power droops, including an extra phase shift loop. The influence of the control parameters on the systems behavior can be studied using the proposed state equation model, which was obtained from the small-signal analysis. The models results are compared with numerical simulations of the nonlinear system to verify their accuracy. Comparisons are also made with experimental data reported in the literature.

An electronic ballast with high power factor and low voltage stress

This paper presents a new configuration for an electronic ballast with high power factor for fluorescent lamps. The proposed ballast consists of the integration of a buck-boost converter, used as an input stage to correct the power factor and regulate the voltage on a dc bus, and a resonant half-bridge inverter to drive the lamp. The buck-boost converter operates at a constant frequency and constant duty cycle in a discontinuous conduction mode during all input cycles.

An optimum ZVS-PWM DC-to-DC converter family: analysis, simulation and experimental results

The authors consider a family of DC-to-DC power converters using the lossless commutation pulse-width-modulation (PWM) source feeding resonant disconnecting circuit cell with resonant cycle interruption (LC-PWM-SF-RDC) to overcome the problems present in quasi-resonant converters (QRCs) and QRCs-PWM. The most important property of this family of devices is the ability to regulate output power and voltage by PWM, with constant operating frequency, without load limitation, and without sacrificing the lossless commutation. The authors present the operating principle and design-oriented analysis, output characteristics, relevant equations, and simulation results. These procedures are validated by a prototype laboratory implementation.<<ETX>>

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

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.

Stand-alone photovoltaic energy storage system with maximum power point tracking

This digests deals with the study of a stand-alone photovoltaic system, which is able to extract the maximum power from photovoltaic array for all solar intensity conditions and to provide output voltage regulation. The proposed system consists of a DC-DC converter in combination with battery energy storage in a simple structure. Operating principle and control strategy are described. Digital simulation is included, supporting the validity of the concept.

A buck quadratic PWM soft-switching converter using a single active switch

High-switching frequency associated with soft commutation techniques is a trend in switching converters. Following this trend, a buck pulsewidth modulation (PWM) converter is presented. The DC voltage conversion ratio of this converter has a quadratic dependence on duty cycle, providing a large stepdown. This new buck quadratic PWM soft-single-switched converter, having only a single active switch, provides a high efficient operating condition for a wide load range at high-switching frequency. In order to illustrate the operating principle of this new converter, a detailed study including theoretical analysis, relevant equations and simulation, and experimental results is carried out.

A boost PWM soft-single-switched converter with low voltage and current stresses

This paper is an improved version of a previous study that described a boost pulse-width-modulated (PWM) soft-single-switched power converter, which, having only a single active switch, is able to operate with soft switching in a PWM way without high voltage and current stresses. In addition, such a power converter can work at high-switching frequencies for a wide load range. In order to illustrate the operating principles of this power converter, a detailed study, including simulations and experimental tests, is carried out. The validity of this power converter is guaranteed by the obtained results.

Proposal of a Soft-Switching Single-Phase Three-Level Rectifier

This paper is concerned with the study of a single-phase boost-type three-level rectifier. The converter is supposed to present high input power factor, low current harmonics, low total harmonic distortion, and simple control scheme. In order to minimize switching losses, a passive nondissipative snubber is associated with the aforementioned converter. The theoretical analysis, design procedure, and analytical results regarding a 1.2-kW prototype are presented to validate the proposal.

A boost converter associated with a new nondissipative snubber

This paper presents a boost converter with a nondissipative snubber which provides a soft switching converter operation. This approach allows the main switch to work in a ZVS way and the auxiliary switch to work in a ZCS way. The nondissipative snubber is composed by two capacitors (resonant capacitors), one inductor (resonant inductor), one switch (auxiliary switch) and two diodes, one in series with the main switch and the other in series with the auxiliary switch. The complete operating principle, relevant equations, simulation results and experimental results are presented.