Electrónica

In this paper a single-switch power supply based on the shunt class E amplifier is presented. A simple and easy method to analyze the complete system is proposed and one way to provide compensation to parameter's variation of the ozone generator and to reduce the size of the resonant inductor is proposed and studied too. The selected topology offers a low-cost and high-power density source that efficiently supplied the system. Experimental results are congruent with the specifications and a high ozone concentration is obtained.

In order to determine the stability of electronic ballasts, it is necessary to use a small-signal model. Various techniques has been proposed to obtain a small signal model; these techniques are complex and require multiple measurements. In this paper, a simple methodology to obtain small-signal model using only a simple test is presented. The parameter of the model are obtained through step response and experimental results validate the procedure.

A ZVT DC-DC converter with stray components integration is presented in this paper. The transformer leakage inductance and the MOSFET output capacitance are used to achieve the ZVT operation of the converter resulting in a high-frequency compact power converter. The circuit operation, the idealized waveforms and the methodology used to calculate the components are explained together with experimental results obtained with a 250 W prototype.

This article presents the development of a model for SiC power diodes based on the physics of the semiconductor. The model is able to simulate the behavior of the dynamics of the charges in the N-region based on the stored charge inside the SiC power diode, depending on the working regime of the device (turn-on, on-state, and turn-off). The optimal individual calculation of the ambipolar diffusion length for every phase of commutation allows for solving the ambipolar diffusion equation (ADE) using a very simple approach. By means of this methodology development a set of differential equations that models the main physical phenomena associated with the semiconductor power device are obtained. The model is developed in Pspice with acceptable simulation times and without convergence problems during its implementation.

In this paper, a single-stage high-power-factor high-efficiency electronic ballast for compact fluorescent lamps is presented. The proposed topology uses two voltage sources connected in series to feed the inverter ballasting the lamp, one of them consists in the rectified line voltage and the other in a dc-dc converter operating in discontinuous conduction mode. In this way, the converter processes a lower energy than the nominal power of the lamp. The proposed topology presents simplicity, high-power-factor, low current crest factor, and high efficiency.

The main function of the on-load tap changing (OLTC) regulators consists of maintaining a constant voltage in order to feed critical loads despite the load changes or voltage changes in the ac mains. The traditional regulators are still used nowadays, but present several disadvantages, like a slow response, which reaches from 100 ms to several seconds. These drawbacks can be overcome if the OLTC regulators would have shorter response time, commuting several times every cycle of the mains. There are two basic topologies for fast OLTC regulators, the first one consists of several taps and uses hard switching. The second one consists of two main switches commuting at high frequency, using softswitching in order to reduce the power losses. The present topology is of the second type. This paper presents a mathematical model of the power stage of the proposed regulator. The model includes the parasitic resistances and the leakage inductances in order to obtain a better comprehension of the regulator operation. A parametric analysis has been done in order to observe the influence of the parasitic elements in the performance of the main parameters of the topology. The model is verified by experimental results obtained using a 500 W prototype.

This paper presents a driver for a HID lamp based on the application of a high frequency current square waveform through the lamp with the goal of avoiding acoustic resonances. The proposed ballast is fed from a 12V dc input voltage and is intended to be used in systems supplied from non-conventional sources, such as back-up batteries, photovoltaic generators and automotive applications. In order to initiate the discharge in the lamp an especially designed igniter supplied from the 12V dc voltage is used to apply high voltage ignition peaks to the lamp. Experimental results obtained from a laboratory prototype for a 70W Metal Halide lamp supplied at 30kHz are also shown to evaluate the possibilities of the proposed topology.

In this paper a novel class E amplifier with two current sources used to implement high-power-factor electronic ballast for fluorescent lamps is presented and evaluated. The circuit is based on the class E amplifier with two current sources, one of them implemented using the main input voltage and the other by means of a bulk capacitor charged from the resonant tank of the class E amplifier. This topology presents a high power factor and low current crest factor and only uses one switch with zero voltage switching. Design guidelines are presented and a 300 kHz electronic ballast fo r a 32 W compact fluorescent lamp was designed and tested.

In this paper, a simple and effective method to obtain the small signal model of discharge lamps by means of step response is presented. The lamp parameters measurement is improved by means of a circuit based on passive elements. This study describes the conditions that must fulfill the parameters extraction, as well as the additional information that provides the step response test. The stability analysis, simulation and experimental results of the lamp-ballast set together with a buckboost converter are presented.

Acoustic resonance phenomenon has bee n the main problem for ti,e develo p ment of dectronic ballast for high intensity discharge lamps opernting at high frequency (Fs > 20 kHz). One of the proposals to solve this problem is the appUcation of the frequency modulation.

Analysis and design of a dimming control based on the Discrete Sliding Mode Control (DSMC) strategy for electronic ballasts (without resonant tank) is presented. To avoid the acoustic resonance phenomenon, the proposed scheme feeds the lamp with low frequency square waves, and then to stabilize the lamp current a dc-dc converter with a closed loop control stage is included. For this purpose a Buck converter with DSMC control is used. A fast response and good reference pursuit is obtained, avoiding the lamp turn off or the lamp destruction when the dimming control is implemented. A reduction in electronic elements is achieved and the reliability of the overall system is incremented with the DSMC compared to the analog Sliding Mode control strategy. The analysis includes those conditions related to the existence of a sliding surface and the stability conditions. The simulations are made with a nonlinear dynamic lamp model. Analysis, simulation and experimental results of the proposed electronic ballast and the control stage are presented.

A b stra c t-In this paper it is presented a new integrated power conditioner topology proposed for a fuel cell based on power supply system. The proposed converter combines the conventional ZVS active clamp full bridge boost converter structure with the sinusoidal pulse width modulation technique to guarantee a sinusoidal output voltage. Particularly, the proposed fuel cell power conditioner is intended for stand-alone ac power generation and low voltage fuel cell input. The main characteristic of the proposed topology is the use of fewer components when compared to the conventional two-stage power conditioners approach reducing the cost. In addition, the total efficiency is increased by reducing the power processing stages. Therefore, it is expected that the proposed integrated power conditioner topology could be effectively utilized for fuel cells applications. It is also presented a compressive analysis of the main characteristics of the fuel cell which will determine the design parameters for the power conditioner. In order to validate the proposed approach, simulation and experimental results are provided for a 100 W integrated power conditioner prototype with 120 V ac output voltage and 26V dc input voltage.

In this paper, a simple and effective method to obtain the small signal model of discharge lamps by means of step response is presented. The lamp parameters measurement is improved by means of a circuit based on passive elements. This study describes the conditions that must fulfill the parameters extraction, as well as the additional information that provides the step response test. With this technique, the polar graphs of a 70W metal halide lamp obtained with step response are compared with those obtained by means of a point to point disturbances injection method. The stability analysis, simulation and experimental results of the lampballast set together with a buck-boost converter are presented

A complete LC and LCC Resonant Tanks analysis for its application in the starting and stabilization of Metal-Halide Lamps is presented in this paper. The operation with a single frequency for the starting and steady-state phases, the maximum gain voltage during prestarting phase, the possibility to achieve soft switching in the switches during the starting and steady-state lamp operation and the resonant tank design limitations for these conditions are considered in the analysis. Experimental prototypes were built to verify the analysis and the results are included.