N. B. Chagas

Single-stage high-power-factor dimmable lighting system for electrodeless fluorescent lamp

The use of the electrodeless fluorescent lamps has been increasing, because of their features such as lifetime and lumen efficiency, when compared to conventional fluorescent and high pressure sodium lamps. The single-stage high-power-factor electronic ballast for electrodeless fluorescent lamp with dimming feature is presented on this paper. It is obtained by integrating a SEPIC converter with a Half-Bridge asymmetric LCC resonant inverter, which can effectively regulate the lamp power. Experimental results are shown, in order to validate the proposed idea. The implemented topology presented a power factor of about 0.995, a total current harmonic distortion of 9.61% and an efficiency of 86%.

High power factor dimmable lighting system for electrodeless fluorescent lamp

The use of the fluorescent lamps without electrodes (electrodeless) has been increasing, because of their features such as lifetime and lumen efficiency, when compared to conventional fluorescent and high pressure sodium (HPS) lamps. This paper presents a luminous flux variation strategy using a Single Ended Primary Inductance Converter (SEPIC), which also provides high power factor correction, to feed electrodeless fluorescent lamps. Since the load is variable a digital compensation is used to meet the control of the specified output voltage in the project, once the dimming characteristic is achieved by varying the SEPIC output voltage. A microcontroller is used in order to allow a suitable control for the converter since it presents features that make possible to obtain dimming capability. The lumens information can be done through wireless system.

Dimmable high power factor single-stage electronic ballast for electrodeless fluorescent lamps

Dimmable high-power-factor electronic ballast is proposed in this paper. The electronic ballast is intended to feed a 100 W electrodeless fluorescent lamp (EFL) at 250 kHz. The proposed topology consists of a buck-boost converter, as power factor correction (PFC) stage, associated with a resonant halfbridge inverter, used as lamp power control (PC) stage. In this work, the integration of both stages is proposed in order to reduce the number of active switches, as well as to simplify the required driving and control circuitry for this application. The dimming system is employed by the shared switch duty ratio control, the power variation oscillated from 100W to 44W. The implemented topology achieved a high power factor (PF), varying between 0.992 and 0.979, the line current total harmonic distortion (THD) varied from 10.016% to 6.78%, while the measured efficiency was around 80%.

Electrodeless fluorescent lamps model operated at high frequency

This paper presents an induction electrodeless fluorescent lamp model for simulation, which employs electric equivalents variables inductor and resistance. Because of the lamp negative impedance feature, it is necessary an electrical equivalent model to perform the lamp behavior in simulations. The induction lamp may be represented by an equivalent inductor in parallel with an equivalent resistance. In this paper the resistance uses exponential and the inductance polynomial fitting. The model was implemented in OrCAD/PSpice. Simulation results and experimental data are presented to verify the model feasibility and accuracy.

Cost comparison between energy consumption and lifetime depreciation for different compact fluorescent lamps starting scenarios

This paper presents an analysis of the benefit-cost ratio of turning off or not a fluorescent lamp in small time intervals, based on the relation between energy consumption and lamp lifetime depreciation. Thus, this paper analyzes compact fluorescent lamp ignition characteristics considering factors such as: electrical performance, lifetime depreciation, power consumption and the relationship between electrical energy cost and lamp lifetime reduction by switching it on/off. The experimental results show the equivalence between the lamp lifetime depreciation and electrical energy cost to keep it on when it is activated for a certain cycled time period.

Analysis and design of a high-power-factor single-stage buck-boost half-bridge electronic ballast for electrodeless fluorescent lamps

In this paper a methodological study of an electronic ballast including design and development issues is presented. The ballast is intended to feed a 100 W electrodeless fluorescent lamp at 250 kHz. The proposed topology consists of a buck-boost converter, as power factor correction (PFC) stage, integrated with a resonant half-bridge inverter, used as lamp power control (PC) stage. The integration of both stages is proposed, in this work, in order to reduce the number of active switches, as well as to simplify the required driving and control circuitry for this application. The implemented topology achieved a high power factor (0.994) and a line current total harmonic distortion (THD) of 8.016%, while the measured efficiency was 85%.

Lighting systems energy efficiency based on different human visual conditions

This paper presents a lighting design analysis in scotopic and photopic conditions of different lamps types. The efficient lighting system concept is usually associated with high performance electronic circuits. However, researches related to the human eye physiology indicate that this efficiency gain can be achieved only by changing the lamp type to be used in each visual condition. Analysis suggests that changing the light spectrum incident on the eye, so that it excites most effectively the photoreceptor cells, light levels can be reduced without compromising the visual performance. On this basis, this paper presents a study comparing the power required, the lighting system investment cost, and the energy consumed cost over 10 years. Therefore, lighting systems based on high pressure sodium lamps, fluorescent lamps, metal halide lamp, and lighting emitting diodes are compared. The final results show that the most efficient lighting system for photopic conditions is based on high pressure sodium lamps. However, under scotopic conditions the best efficiency is obtained with the use of metal halide lamps.

Analysis of losses in the core of an electrodeless fluorescent lamp

An investigation of magnetic core losses of an electrodeless fluorescent lamp is presented in this paper. These losses can be divided into two different kinds: static, which is related to hysteresis effects, and dynamical, associated to parasitic effects. Experimental results (at 25° C) demonstrate that the total losses, in nominal condition point, are approximately 3.18 W, what represent 3.18% of the power supplied to the lamp. In this same point, the static losses are approximately 1.31 W and the dynamic losses about 1.87 W. Based on this, the static losses represent about 41% of total loss related to the magnetic core while dynamical losses represents 59% of total loss.

Comparison between integrated and non-integrated SEPIC half-bridge electronic ballasts for electrodeless fluorescent lamp applications

A comparison between integrated and non-integrated topologies to feed a 100 W electrodeless fluorescent lamp (EFL) at 250 kHz is presented in this paper. The analysis considers efficiency, power factor (PF) and line current total harmonic distortion (THD) of the electronic ballast. A dimming feature is provided to investigate the system behavior when the lamp power decreases. The proposed topologies are composed of a Single-Ended Primary Inductance Converter (SEPIC), used as power factor correction (PFC) stage and a resonant half-bridge inverter, used as lamp power control (PC) stage. The integration is made between the PFC and PC stages. This process is usually employed in order to reduce the number of active switches, as well as to simplify the required driving and control circuitry. For the non-integrated topology two different frequencies were used in the PFC stage, 40 kHz and 250 kHz. The implemented topologies attained very high PF, greater than 0.98 for all ballasts, and low line current total harmonic distortion (maximum 15.56% at rated power), without using electromagnetic interference (EMI) filter. The measured efficiency varied from 85% to 92% at nominal lamp power.

Model for electrical characteristics of Electrodeless Fluorescent Lamps

This paper presents an electric equivalent model of the Induction Electrodeless Fluorescent Lamps (IEFL). The model is based on resistances and reactances and takes into account the real and reactive lamp power. One of the most important features of the proposed methodology is the concern regarding core losses and lamp reactive characteristics. In order to obtain and validate the IEFL model, a series-parallel resonant half-bridge inverter is used as the ballast power stage. Lamp discharge and coils are modeled as resistances and reactances depending on the lamp power. Simulations employing the proposed model are presented in this paper and they are in agreement with experimental results.