Lamp Current Crest Factor Research Articles

A Generalized Dynamic Conductance Model for High Intensity Discharge Lamps and its Prospective Application to Design Dimmable Electronic Ballast

A generalized model for high intensity discharge (HID) lamp is developed based on the Francis-Damelincourt dynamic conductance model of electric discharge by replacing the model constants A, B, C, D with four experimentally determined coefficient functions of rated lamp power and root mean square supply voltage. Experimental validation of this model is done, which shows a maximum deviation of about 5 %. Moreover, sensitivity analysis for the model coefficients is also performed, results of which conform to the physical behaviour of high pressure sodium (HPS) and metal halide (MH) lamps. This model is capable to simulate electrical characteristics of HPS and MH lamps of wide range of commercially available rated power (70–400) W fed by a wide range of supply voltage (180–250) V, 50 Hz. As a prospective application, the model is applied to design dimmable low frequency square wave electronic ballast for HID lamps. A design algorithm is proposed for this purpose. Performance analysis of the designed ballast is conducted in Matlab-Simulink environment, which shows fairly good performance of the circuit in terms of dimming accuracy (maximum deviation 2.64 %), lamp power factor (≥ 0.993), and lamp current crest factor (equal to 1.0). The model can also be utilized for designing electronic ballasts of other topologies.

A design methodology for acoustic resonance-free, high-frequency, dimmable electronic ballast for high-pressure sodium-vapour lamps

This paper presents a methodology to design acoustic resonance-free, high-frequency, dimmable electronic ballasts for high-pressure sodium vapour (HPSV) lamps having a range of rated wattage (70–400 W). After estimation of the ‘quiet window’ of an HPSV lamp, the proposed iterative algorithm is able to determine the acoustic resonance-free driving frequencies of a design ballast corresponding to 50%–100% power level. On the other hand, a developed wattage and voltage independent HPSV lamp model facilitates finding the required electrical characteristics of HPSV lamps without performing laboratory experimentation. Using the estimated driving frequencies of a design ballast and the synthesized electrical characteristics of the lamp, the design circuit parameters of an electronic ballast are determined. Performance evaluation of the designed ballasts, carried out on the Matlab–Simulink platform, indicates several important attributes, viz. higher power control accuracy (deviation ≤3.69%), near-unity lamp power factor (≥0.98), lower lamp current crest factor (<1.7) and lower lamp current total harmonic distortion (≤12.63%). Results establish the effectiveness of the proposed design methodology to design lightweight and compact electronic ballasts for HPSV lamps with less effort than conventional design practice.

High‐power‐factor electronic ballast zero voltage switching and low d v/ d t with combination of charge pump and valley fill based on class DE

In this study, for application of 36 W/220 Vrms/50 Hz fluorescent lamp, a high performance of high-power-factor and low line input current harmonics of electronic ballast is proposed. The proposed ballast has a structure based on a combination of charged pump and valley fill circuit. By adding paralleled capacitors to each power switch and setting the circuit parameters, operation modes of the inverter can be modified from single-stage conventional class D to a class DE. Consequently, duty ratio can be reduced by up to 25% so that the voltage stress at power switch is lower when compared with the conventional class D inverter. Furthermore, switching power loss and dv/dt can also be reduced because of zero voltage switching condition. Details of design and circuit operation are described. The experimental results of prototype circuit, operated around 50 kHz of switching frequency at full power output, show that the proposed ballast has 94.48% of efficiency, 4.30% of THDi, 0.996 of input power factor and 1.38 of lamp current crest factor.

A Single-Switch Valley-Fill Power-Factor-Corrected Electronic Ballast for Compact Fluorescent Lightings With Improved Lamp Current Crest Factor

Although compact fluorescent lamps (CFLs) have been on the market for a long time, many of them do not achieve the same power factor as the incandescent lamps do, which presents a significant problem for the utility with the current widespread use of CFLs for household lightings. A simple single-switch electronic ballast with passive valley-fill power factor correction is proposed in this paper for CFL application. The proposed single-switch ballast circuit is able to achieve zero current switching to maximize the circuit efficiency. A simple feedback circuit with duty ratio control is also proposed to improve the high lamp current crest factor caused by the valley-fill circuit. Detailed descriptions and analysis of the circuit operating principles are provided in this paper. Simulation and experimental results are given on a 13-W CFL tube from Osram Sylvania to highlight the merits of the proposed work.

A Dimming Module for Controlling Power Supplying to a Fluorescent Lamp Ballasted by a Nondimmable Electronic Ballast

A dimming module for controlling the power supplying to a fluorescent lamp ballasted by a nondimmable electronic ballast is proposed. It is physically connected across the lamp tube to perform the dimming operation. The methodology is based on diverting the current supplying to the lamp tube to adjust the lamp power. The current diverted is in phase quadrature with the lamp voltage. The power stage of the module consists of a series-resonant inverter operated as a reactive-power controller. On dimming the lamp, it will increase the filament voltage for maintaining good thermionic emission of electrons from the filament. More importantly, it enables dimming function without detriment to the input-power quality of the ballast and lamp-current crest factor. The operating principle, control of the module, and the design procedure are described in this paper. An experimental prototype for dimming a 28 W T5 lamp has been built. The module is applied to one of the two lamps that are both ballasted by a commercial-electronic ballast for dual lamps. Experimental results show that the proposed module can adjust the power supplying to the lamp with the dimming module from 100% to 30% of the full power. A comprehensive study into the electrical characteristics of the ballast, lamp operational characteristics, and system efficiency at different dimmed conditions will be presented.

Single-Stage Electronic Ballast Using Class-DE Low-${d} \upsilon/{d}t$ Current-Source-Driven Rectifier for Power-Factor Correction

A single-stage high-power-factor electronic ballast with a Class-DE low- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> v/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dt</i> rectifier as a power-factor corrector is proposed in this paper. The power-factor corrector is achieved by using a bridge rectifier that acts as the Class-DE low- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> v/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dt</i> rectifier. The Class-DE low- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> v/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dt</i> rectifier is driven by a high-frequency current source, which is obtained from the square-wave output voltage of the Class-D parallel resonant inverter through an <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -series circuit. By using this topology, the conduction angle of the bridge rectifier diode current is increased, and a low line-current harmonic is obtained. A prototype ballast is implemented to drive a 36-W fluorescent lamp. The switching frequency is fixed at about 84 kHz. Experimental results verify the theoretical analysis. The designed electronic ballast has a power factor of 0.99, a total harmonic distortion of 1.3%, a lamp current crest factor of 1.42, and 90% efficiency at full power.

A simple PWM method for improving lamp current crest factor of valley‐filled electronic ballast

AbstractIn this paper, a PWM method to improve the lamp current crest factor (CCF) of the valley‐filled electronic ballast (VFEB) is presented. The VFEB has merits of high power factor, simple structure, and low cost. However, it results in an excessive CCF, which will shorten the lifetime of low‐pressure discharge lamp. The proposed method controls switching duty ratio by feeding forward the dc‐link voltage waveform of VFEB. It decreased the duty ratio with rising of dc‐link voltage. Therefore, the proposed method could restrain the lamp peak current and improve the lamp CCF. The control block diagram and basic theory are introduced to improve the CCF. The computer simulations verify the proposed method and derive a minimum lamp CCF. The experimental results demonstrate that the lamp CCF was reduced from 1.9 to 1.58, the ac line power factor is 96%, and the input current THD is 29.3%. The fixed switching frequency operation gains a satisfactory power quality. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Single-stage electronic ballast with class-E rectifier as power-factor corrector

A single-stage high-power-factor electronic ballast with a Class-E rectifier as a power-factor corrector is proposed. A Class-E rectifier is inserted between the front-end bridge rectifier and the bulk filter capacitor to increase the conduction angle of the bridge-rectifier diode current for obtaining low line-current harmonics. The Class-E rectifier is driven by a high-frequency sinusoidal current source, which is obtained from the square-wave output voltage of the Class-D inverter through an LC series resonant circuit. A high-frequency transformer is used for impedance matching. The experimental results for a 32-W prototype ballast are given. The switching frequency was 61.3 kHz. At full power, the power factor was 0.992 and the total ballast efficiency was 88.3%. The lamp-current crest factor was about 1.36. The simulated and experimental results were in very good agreement.

Reator eletrônico auto-oscilante "valley-fill" com correção do fator de crista utilizando modulação em freqüência

Neste artigo, apresenta-se um reator eletrônico auto-oscilante empregando o filtro valley-fill modificado como método de correção do fator de potência, de modo a atender a norma IEC 61000-3-2 Classe C. Para solucionar o problema do alto fator de crista da corrente na lâmpada fluorescente inerente ao filtro "valley-fill", emprega-se um sistema de modulação em freqüência. Um circuito simples e de baixo custo mantém o fator de crista abaixo do limite de 1,7. São utilizadas as características de ganho do filtro ressonante aliadas à possibilidade de controlar a freqüência do circuito de comando auto-oscilante a partir da característica da tensão de barramento do reator.

A New Mathematical Tool to Meet IEC 61000–3–2

From January 2001 all lighting products on the European market had to be IEC 61000-3-2 compliant. The IEC 61000-3-2 standard sets limits on the 3rd and 5th harmonic input current as well as the conduction angles. Low power lighting products were not initially compliant to the new standard because the value of the DC bus capacitor was too high. Choosing a very low capacitor value is not advisable as it increases the lamp current crest factor and reduces the life of the product. Therefore, selection of the capacitor value is a trade off between the lamp current crest factor and the level of input current distortion. This paper presents two simple mathematical tools to determine the capacitor value to meet the IEC 61000-3-2 specifications and to predict the performance of the CFL lamp for a given input voltage and lamp power. Based on mathematical modeling, two mathematical tools have been developed. The first mathematical tool determines the maximum capacitor value that satisfies IEC 61000-3-2 requirement for low power lighting products. Based on the capacitor value selected by the first mathematical tool, the second mathematical tool determines the magnitudes of the third and fifth harmonic in the input current, conduction angles, power factor, THD and a DC bus crest factor. The two mathematical tools proposed in this paper are the simplest and cheapest ways to meet the IEC 61000-3-2 standard and predict the performance of the lamp. More important the proposed tool can be widely used for all low power lighting products in the countries where IEC 61000-3-2 has not yet been introduced. By using the proposed method the cost of an electronic ballast is reduced and the power quality significantly improved. By reducing the capacitor value, the lamp current crest factor is slightly increased but it is still acceptable for CFLs. Results obtained from the proposed mathematical tools have been validated with experimental results for 9, 15 and 23 W lamps.

Improving crest factor of electronic ballast-fed fluorescent lamp current using pulse frequency modulation

In case where electronic ballast employing a valley-fill passive power-factor correction (PFC) circuit is used for feeding fluorescent tamps, a new method to reduce crest factor of the lamp current is studied in this paper. It is known that a 50% valley-fill passive PFC provided for high input power factor results in undesirable value of crest factor of the fluorescent lamp current, In order to reduce crest factor to a lower value, a pulse frequency modulation technique based on the waveform of the DC-link voltage which is predetermined by the passive PFC circuit is taken into the switching control action of the electronic ballast. An equation-based analysis between the crest factor of lamp current and the effect of varying the inverter switching frequency is comprehensively performed. Several simulation and experiment results illustrate the Effectiveness of the proposed control scheme.

Analysis and experimental results of a single-stage high-power-factor electronic ballast based on flyback converter

A new single-stage high-power-factor electronic ballast based on a flyback converter is presented in this paper. The ballast is able to supply a fluorescent lamp assuring a high-input power factor for the utility line. Other features are lamp power regulation against line voltage variations and low lamp current crest factor, both assuring long lamp life. The ballast is analyzed at steady-state operation, and design equations and characteristics are obtained. Also, a procedure for the ballast design is presented. Finally, simulation and experimental results from a laboratory prototype are shown.

A study on discharge lamp current waveforms in constant wattage ballast systems.

This paper is concerned with the experimental investigation of the effects of the performance characteristics of the choke type constant wattage ballast on the lamp current waveforms or the values of the lamp current crest factor. The re-ignition phenomenon of the discharge lamp under AC operation is represented by an incomplete switch which consistes of a switch and an effective resistances in both the abnormal glow and the arc discharge regions. The high peaky lamp current is attributed to the transient phenomenon of the lamp operating circuit when the discharge lamp re-ignites. The effects of several ballast circuit elements, such as the magnitudes of both the capacitance and the series linear reactor, the magnetic characteristic and the geometry of the saturable auto-transformer, on the lamp current crest factor are experimentally investigated.

Design method and electrical characteristics of choke type constant wattage ballasts for discharge lamps

The designs and the performances of the chock type constant wattage ballasts are discussed. The fundamental quantities for design, such as the reactance values of the linear chock coil and turns ratio of the saturable auto-transformer related to as function of the auto-transformer secondary voltages under normal operation and variable K, which are indicated by ratios of the magnetizing current of the auto-transformer referred to the secondary to the rated lamp current, besides the line and lamp ratings. It is then carried forward according with the particular specification to design the linear choke coil and the saturable auto-transformer in terms of window and core cross sectional areas, core and copper volumes and others, and then, the electrical characteristics, such as the lamp wattage regulation, the lamp current crest factor, and the ballast losses, are investigated from various points of view, such as variable K, the secondary voltage and the flux density of the auto-transformer under normal operation, coefficient of specific voltage, and others.