Dimmable electronic ballasts by variable power density modulation technique

Dimming can be accomplished commonly by switching frequency and pulse density modulation techniques and a variable inductor. In this study, a variable power density modulation (VPDM) control technique is proposed for dimming applications. A fluorescent lamp is operated in several states to meet the desired lamp power in a modulation period. The proposed technique has the same advantages of magnetic dimming topologies have. In addition, a unique and flexible control technique can be achieved. A prototype dimmable electronic ballast is built and experiments related to it have been conducted. As a result, a 36WT8 fluorescent lamp can be driven for a desired lamp power from several alternatives without modulating the switching frequency.     

Group-Asymmetrical PWM Control for Dimmable Fluorescent Lamp Ballast Without Striation and Thermostat Effect

In this paper a group-asymmetrical pulsewidth modulation (GAPWM) by signal process is explored to modulate the lamp current comprising even and odd harmonics, which can then eliminate striation and thermostat effects in a fluorescent lamp. Using GAPWM control, a hiding dc, like an electron cloud inside the lamp, disappears and good rejection to the thermostat effect is achieved since the average lamp current is null in the whole group period. The proposed ballast can actually operate in continuous-conduction mode to keep zero-voltage switching achieving a high power efficiency up to 90%. High lighting efficiency 20% more than that of the traditional ballast is also achieved. The fluorescent lamp is capable of obtaining wide dimmer range between 100% and 0% of the full luminance.      

Improving crest factor of electronic ballast-fed fluorescent lampcurrent 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     

Development of a distributive control scheme for fluorescent lighting based on LonWorks technology

In this paper, a new distributive control system for indoor fluorescent lighting based on LonWorks technology is presented. The system features the following elements: microprocessor-controlled fluorescent lamp electronic ballast, communication system using the power line as communication media, and control software for Windows 95 environment. The electronic ballast has been especially designed to be operated under the proposed distributive control system. Thus, it features high-input power factor, high-frequency lamp supply, lamp power regulation against line voltage variations, dimming capability, and lamp failure detection. With this scheme, a low-cost distributive control system for lighting applications has been achieved, allowing energy and maintenance savings and increase in the reliability of the fluorescent lighting systems.     

工程实践背景下的荧光灯电路实验

为使学生更深刻理解荧光灯电路实验的基础性和可扩展性,针对常规荧光灯实验的内容和要求相对简单,仅限于复现荧光灯的工作原理及如何提高功率因数,缺少对实际工程问题的深入探索,设计了荧光灯电路综合研究实验。从电子镇流器产生谐波、供电电源波形畸变、不受控制的谐波存在危害等工程实际问题切入,引导学生认识供电系统谐波的问题,掌握周期性非正弦电压信号的分析方法。几年的教学实践结果表明,本实验的开设可以培养学生养成研究的习惯,激发学生深入探究理论知识与实际工程实践之间的差异、自主学习相关知识的兴趣。     

Remote identification of liquids in a dielectric container using millimeter waves. 1. Principal possibility

Thepossibility of applying short-range radiolocation in millimeter wave range for problem of remote identification of flammable and hazardous liquids, enclosed in dielectric containers is demonstrated for the first time. Developed measurement setup allows indoor investigations; and the level of emitted power of utilized devices is insignificantly higher than background noise level, or, equivalently, thermal radiation. The described radiometric measurement setup enables discriminating liquids having different physical and chemical properties, in particular discriminate between water and gasoline containers. Applying additional illumination, which increases the contrast of the object under test, is one of one of the features of developed design. Various noise sources were investigated to be used as additional illumination. It was shown that in case of short-range radiolocation, energy-efficient fluorescent lamp is the most affordable choice of radiometric illumination. Such lamp not only ensures sufficient noise level in the operating frequency domain, but also has in-built modulation device that allows using modulation regime of the receiver and enables higher sensitivity.     

A Semi-Theoretical Fluorescent Lamp Model for Time-Domain Transient and Steady-State Simulations

Low-pressure discharge lamps obey a set of physical laws that are different from those of high-pressure discharge lamps. In this paper, these differences are addressed. Based on a recently developed HID lamp model frame, a semi-theoretical fluorescent lamp model that can be determined by genetic algorithms and simple electrical measurements is presented. This model does not require any lamp data from lamp manufacturers. Its parameters can be determined from electrical voltage and current measurements of the lamps under AC operation at mains frequency. With the same set of parameters, the model can predict the lamp terminal characteristics accurately under low, medium and high frequency operations. Good simulation results were achieved when the lamp power was reduced to 60% of rated power and when the lamp was operated under step-up and step-down transient processes. Simulation results for different sizes of tubular and compact fluorescent lamps agree well with their experimental results. Particularly, the differences between simulation results and experimental results under rated power are less than 10%. Hence, the proposed model shows a good degree of accuracy: 1) for different types of fluorescent lamps; 2) at different operating frequencies; 3) under different dimming levels; and 4) during step-up and step-down transient processes.     

TRIAC dimmable ballast with power equalization

A two-stage, two-wire TRIAC dimmable electronic ballast for fluorescent lamps is presented in this paper. It is constructed by using a flyback converter as the input power factor corrector to supply a half-bridge series-resonant parallel-loaded inverter to ballast the lamp. The flyback converter is operated in discontinuous conduction mode so that the filtered input current profile is the same as the TRIAC-controlled voltage waveform. The switches in the inverter are switched at a constant frequency slightly higher than the resonant frequency of the resonant tank. Based on the constant average input current characteristics of the inverter, the dimming operation is simply achieved by pulsewidth modulation control of the magnitude of the flyback converter output voltage. No synchronization network is required between the input and output stages. In addition, a linear power equalization scheme is developed so that the dc-link voltage (and hence the lamp power) is in a linear relationship with the firing angle of the TRIAC. The average output voltage of the dimmer controls the equalized flyback converter output voltage. Modeling, analysis, and design of the ballast will be described. A prototype was implemented to verify the experimental measurements with the theoretical predictions.     

Analysis and experimental results of a single-stagehigh-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     

Comparative Analysis and Experiments of Resonant Tanks for Magnetically Controlled Electronic Ballasts

This paper presents a comparative analysis and experiments of resonant tanks for magnetically controlled electronic ballasts, focusing on their behavior and performance when driving hot cathode fluorescent lamps. Four different resonant tanks are analyzed: LC, LCC, capacitive impedance inverter, and CLL. The analysis is performed using a 36-W fluorescent lamp, which has been previously tested and modeled experimentally. The lamp model is used to derive the dimming characteristics of the different resonant tanks when using the resonant inductance as a control parameter. Analysis and experiments showed that instabilities appear when the lamp power is decreased below a minimum value, which effectively limits the dimming range of the ballast. Nevertheless, the proposed control method can be used to control lamp power in an adequate range provided that the resonant tank should be selected and designed properly.      

High frequency electronic ballast provides line frequency lampcurrent

Most electronic ballasts for fluorescent lamps provide a sinusoidal lamp current at the switching frequency. The high-frequency current flowing through the lamp can generate significant radiated noise, which is unacceptable in noise-sensitive applications, such as fluorescent lights in airplanes. Using shielded enclosures for the lamps may solve the problem, but it is expensive. A discontinuous conduction mode (DCM) electronic ballast topology is presented which drives the lamp with line frequency current, just like a magnetic ballast. However, compared to a magnetic ballast, its weight is substantially reduced due to operation at 40 kHz switching frequency. The topology also ensures unity power factor at the input and stable lamp operation at the output     

A high-power-factor electronic ballast using a flyback push-pullintegrated converter

This paper describes a high-power-factor electronic ballast for fluorescent lamps. The converter offers a high power factor and a high-frequency supply to the lamp using a single switch. In spite of its simplicity, an excellent performance concerning load and supply is achieved, ensuring a sinusoidal and in-phase supply current. High power factor is achieved by using a flyback converter operating in discontinuous conduction mode. Operating principle, design equations, component stress, and efficiency are presented. Experimental results have been obtained for one 40-W fluorescent lamp operating at 50-kHz switching frequency and 220-V line voltage     

基于单片机的新型节能日光灯系统的设计

针对目前普通日光灯因不能调节光强而造成的能源浪费问题,设计了一种基于单片机的新型节能日光灯系统,该系统主要分为3个部分,首先采集外界光强信息并将数据传至单片机;随后单片机根据输入量的不同调整输出的PWM波;最后日光灯控制电路通过PWM波的控制,调节日光灯两端的电压,控制日光灯输出的光强,使日光灯随外界光强的变化而自动调整照射光强。经过不同外界环境的实验调试,在满足使用者的用光要求的前提下,日光灯工作稳定,功率明显降低,适宜推广使用。     

基于IR2166的色选机1.7米光源灯管镇流器设计

介绍IR2166镇流器控制器特点;根据色选机对荧光灯光源的要求,依据1.7米55W灯管的参数,详细阐述基于IR2166完成集有源功率因数(PFC)、驱动控制及完善保护于一体的达到色选机光源要求的1.7米荧光灯管镇流器设计。     

带功率因数校正的LED日光灯驱动电源

文中提出了一种带功率因数校正的LED日光灯驱动电源,该电源具有电路简单、可靠的优点,实测数据表明,在较宽电压范围内,驱动电源工作稳定,其具有较高功率因数.     

Charge pump power-factor-correction dimming electronic ballast

A voltage-source charge pump power-factor correction (CPPFC) continuous dimming electronic ballast is proposed in this paper. The basic charge pump PFC principle is presented, and its unity power factor condition is then reviewed. Constant lamp power control and crest factor correction technique in dimming mode operation are then discussed. A continuous dimming controller with average lamp current control and duty-cycle modulation is developed so that the lamp is able to operate in constant power and low crest factor from 20% to 100% dimming level. The developed dimming electronic ballast has features of higher than 0.99 power factor, low crest factor, and low-DC-bus voltage     

A single-stage electronic ballast with high power factor

A single stage electronic ballast with high power factor (HPF) is proposed in this letter. The single-phase boost-type rectifier provides HPF. A saturable transformer constituting the self-oscillating drive limits the lamp current and dominates the switching frequency of the ballast. Experimental results obtained on a 40 W fluorescent lamp are discussed     

New charge pump power-factor-correction electronic ballast with awide range of line input voltage

A new charge pump power-factor-correction (CPPFC) electronic ballast with a wide range of line input voltage is proposed in this paper. Circuit derivation and DC-bus voltage stress at start-up mode are discussed. The average lamp current control with switching frequency modulation is developed to achieve constant lamp power operation and low-crest factor. The proposed CPPFC electronic ballast is analyzed, implemented, and evaluated. It features continuous line input current, low total harmonic distortion (THD), constant lamp power operation, low-crest factor, and less switching current stress with low-DC-bus voltage stress for the line voltages from 180 to 265 V     

荧光灯自动调光系统的研究

在图书馆、博物馆等大型场所,恒亮度的照明系统具有非常广泛的应用前景.利用光敏电阻作为光强采集元件,建立了一种能够根据外界光强自动调节灯功率的照明系统,并介绍了自动调光电路的系统框图,包括光敏电阻测试电路、调光电路等.主要针对光敏电阻的Pspice模型、荧光灯模型和调光理论进行了理论分析.仿真结果表明了上述理论的正确性,该系统能够保证室内的恒亮度控制.     

Single-stage line-coupled half-bridge ballast with unity power factor and ripple-free input current using a coupled inductor

A single-stage line-coupled half-bridge ballast with unity power factor and ripple-free input current using a coupled inductor is proposed. The proposed power-factor-correction circuit can achieve unity power factor and ripple-free input current using a coupled inductor. A saturable transformer constituting the self-oscillating drive limits the lamp current and dominates the switching frequency of the ballast. The proposed ballast has high energy efficiency, low cost, and high reliability compared to the conventional high-power-factor electronic ballasts. Experimental results obtained on a 30-W fluorescent lamp is discussed.