LED Drive Technology Based on CFL Ballast Topology

Transcription

1 Volume 53, Number 3, 0 35 Drive Technology Based on CFL Ballast Topology Petre-Dorel TEODOSESCU, Mircea BOJAN, Ioana-Cornelia VESE and Richard Marschalko Abstract: This research paper presents a practical approach in terms of using the technology found in CFL lighting devices for controlling the new types of high power light emitting diodes, (). Advantages, like good reliability and cost efficiency of the electronic ballasts found in CFL, which can be used in future based lighting devices are representing a very good prospect for research but also good opportunity in terms of high mass implementation. This unified technology will be presented in this paper by means of practical measurements and Orcad/PSpice simulations. Key words: compact fluorescent lamp, light emitting diode, half bridge inverter, resonant tank. INTRODUCTION For decades the incandescent bulb has been the first option in artificial lighting. The global energy demand has exponentially increased, and, as a result, the necessity of founding new, more efficient lighting devices has occurred. For the last 0 years, this option was the CFL, not so well recognized by the consumers like a good overall incandescent lamp replacement most because of the cost and poor light quality for the cheap models [],[]. Nowadays, the incandescent bulb is rejected from the markets by government s decisions, so for now the CFL represent the only economical Manuscript received April 9, 0. This paper was supported by the project "Doctoral studies in engineering sciences for developing the knowledge based society-sidoc contract no. POSDRU/88/.5/S/60078 project co-funded from European Social Fund through Sectorial Operational Program Human Resources Fig.. Electronic schematics of a classic CFL. option for Edison type, artificial lighting lamps. In the last years a new trend has energized the artificial lighting industry and that is the light emitting diode,. According to [3],[4],[5] these diodes could represent a breakthrough in terms of low energy consumption, long expected lifetime, good light spectrum, small size, a.s.o.. STATE OF THE ART IN CFL AND LIGHTING DEVICES The most common CFL technology is composed by an electronic ballast and a fluorescent tube mounted in an Edison type enclosure. In this paper we will be focused on the electronic ballast, where we try to analyze the great potential of this part. Most common ballast topology found in CFL is the self-oscillating, half-bridge inverter. The accurate electronic schematics of a real market CFL is presented in Fig.. 0 Mediamira Science Publisher. All rights reserved.

2 36 ACTA ELECTROTEHNICA The investigation of the working principle of the whole ballast is not an objective of this paper. We will be focused on modeling the schematics so that we are able to carry out the analytical analyze of the behavior of the system when the load is composed by a fluorescent tube. According to [6], [7] the electrical behavior of a fluorescent tube under high frequency and voltage is like a pure resistor. The value of the fluorescent tube for an W CFL is around kω. In the last few years one of most dynamic industries is the light emitting diode,, market. This is because of the great potential of this type of lighting device. Two of the most important advantages for the lighting systems are the luminance efficiency associated with a long expected working lifetime. With a view to transform the light emitting diode into an incandescent lamp replacement device we need to take into account its working principle and the right control system, [8]. In the Fig. we can see that the forward voltage of a regular is decreasing with the junction temperature. This means that the intensity of the output light could change with temperature. Unfortunately, the operation of the s in the lighting devices is normally associated with high temperature variations. This negative effect could be prevented if the drive circuit is not controlling the forward voltage of the but the passing trough. This aspect is worldwide accepted. As a result, the control system of a must be a constant drive. In the drive industry there are a few of constant drive technologies, based on controlling the with the help of a sense resistor. To obtain a constant drive, the circuit, which most of the time is a PWM controlled device, is sensing the voltage drop on the sense resistor. If this voltage is kept to a constant value, this means that we have a constant through the. This could be represented like in Fig. 4. Fig. 4. General constant control for lighting devices. The value of the sense resistor, could establish the value of the passing through the. The most common drive topologies used by the -drive industry are the classical buck (Fig.4), boost, buck-boost or flyback. In this paper we will be focused on a new, different way of establishing a constant through the, with the help of a quasi-resonant converter. 3. CFL AND UNIFIED TECHNOLOGY Fig.. forward voltage drop with the junction temperature. The electric representation of a [9],[0] could be done like in Fig. 3, where it could be presented as a voltage source mounted in series with a resistor and a diode, but also like a Zener diode. Fig. 3. Possible equivalent model. According to our proposed system, the CFL ballast will have as a load not the equivalent resistance of a fluorescent tube but the electrical representation of a, connected via a simple, high frequency, singlephase, bridge rectifier. As a result, the actual CFL ballast becomes a driver without any changes in the electronic schematics. The old self-commutated inverter operates now as a parallel connected, quasiresonant dc-to-dc converter. These presumptions will be analyzed by means of Orcad/Pspice simulations and practical measurement. This investigation is necessary because the transient behavior of the circuit becomes now more complex as in the case of the CFL and because it is very important to prove that we achieve the necessary constant operation mode for the. Fig. 5 presents the proposed electronic schematics were the resistance of the fluorescent tube is replaced by the high frequency, full bridge rectifier associated with one of the two equivalent representations of a. In order to analyze the constant behavior of the system we need to simplify the electronic schematics to a level where we can apply the analytical

3 Volume 53, Number 3, 0 37 relations. According to Fig.6 the input alternative voltage supply, the low frequency rectifier and the low pass LC filter will be modeled as a simple continuous voltage supply. Fig. 5. Electronic schematics of a controlled by CFL ballast. Fig. 8. Model of the high frequency rectifier bridge and the load. Fig. 6. Model of the CFL input schematics. The self-oscillating inverter will be considered like a half-bridge, fixed frequency controlled inverter, as presented in Fig.7. Fig. 9. Equivalent schematics of a controlled by CFL ballast. Fig. 7. Modeling of the inverter and DC voltage divider. In Fig. 8 the high frequency, full bridge rectifier and the Zener diode representing the are replaced by two Zener diodes. After the above simplification, the resulted circuit is presented in Fig.9. This shows an inverter supplied from a double, bipolar intermediate DC link, a resonant tank (L, C) and the reversed Zener as load. According to Figure 0, the inverter generates at his output a rectangular bipolar alternative voltage. Fig. 0. Ideal waveform of a the inverter output voltage. We observe that we have uc () t U ( U - Zener diode voltage). The differential equation that describes the operation mode of the circuit from Fig. 9 is:

4 38 ACTA ELECTROTEHNICA D45 N6650 D46 N6650 FREQ = 50 VAMPL = 3V VOFF = 0 D36 V D37 R58 D35 D38 C35.8u L3 5.7mH D39 C30 n D4 R30 470k R3 470k R3 350 L6 8uH R34 C36 47n U Qmje3003 L4 80uH C.n L.44mH D47 N6650 D48 N6650 D49 DN474 D50 DN474 D5 DN474 D40 C3.n DIAC D4 R L5 8uH Qmje3003 R35 C33 47n 0 K K K_Linear COUPLING = 0.9 Fig.. Orcad/PSpice model for the proposed circuit Input rectified and filtered DC voltage ms 0ms 40ms 60ms V(C35:) 40 DC voltage across condenser C3 from Fig.5. DC voltage across condenser C4 from Fig ms 0ms 40ms 60ms V(C36:,C36:) V(C33:,C33:) 40 0 Input voltage ms 0.05ms 0.0ms V(D45:A,L4:) Experimental results PSpice Simulation results Fig.. Input circuit behavior.

5 Volume 53, Number 3, 0 39 () ( ) ( ) dis t L i t d t d( t) C () C If the Zener diode is not conductive, the circuit is a resonant one. When appears the break-down of the Zener diode, from () we can write: U ( ) () u C U di S t () d() t L L Where, u ( C) is the change of the forward voltage with junction temperature (Fig ). We can admit that: u ( temp) U. Then, supposing that the inductivity of the coil L is high enough, from (), we obtain the constant average behavior of the circuit. Due to the high self-oscillating frequency of the circuit, the contribution of the resonant timeintervals is negligible from the point of view of the general operation of the investigated. The conclusions of this analyze are well confirmed by the simulations with the help of a Orcad/PSpice model and by the experiments on a test bench. 4. PRACTICAL AND SIMULATED RESULTS FOR THE PROPOSED CIRCUIT In order to support the presented information we developed an Orcad/PSpice model for the circuit from Fig. 5. The model is presented in Fig.. The experimental model has the exact electronic schematics from Fig. 5. The functioning behavior of this model along with the simulation model will be compared in this chapter. Fig. presents the behavior of the input circuit, intermediate DC voltage divider and the output voltage of the inverter. The experimental results confirm the simulations of the investigated driver. We can conclude with out of doubt that the two models are acting the same. inductor L 0A condenser C ms 0.05ms 0.050ms -I(L) I(C) inductor L 0A Not rectified Output ( ) ms 0.05ms 0.050ms -I(L) I() condenser C 0A Not rectified Output ( ) ms 0.05ms 0.050ms I() I(C) Experimental results PSpice Simulation results Fig. 3. Waveforms of the resonant tank and output s.

6 40 ACTA ELECTROTEHNICA Output ( ) Output voltage ( voltage) Experimental results 00mA SEL>> -00mA 5 38V 5V 3V -I(D49) 0.000ms 0.05ms 0.050ms V(D49:,D5:) PSpice Simulation results Fig. 3 presents the behavior of the resonant tank and of the output load. Fig. 4 indicates the and voltage after the high frequency rectifier. At this point in our research we consider unnecessarily to use an output condenser filter. From Fig. 3 we can conclude that the functioning cycle could be divided into two periods. First period would be characterized by the fact that the is 0 and because of this, the circuit is working under resonant principle. After that, when the is different form 0, the operation of the circuit is based on the voltage source behavior of the reversed Zener diode (). Now, the circuit is not working under resonant characteristics. It is acting like a source and the is fed by the resonant tank inductor. The resonant behavior will occur again when the will be CONCLUSIONS AND OUTLOOK In this paper it was presented a new possibility of controlling the s with the help of CFL electronic ballast. All this has been proved by means of analytical investigation of the physical phenomenon, practical measurements and Orcad/PSpice simulations. The possibility of using the exact CFL electronic ballast and adding just a high frequency rectifier in order to control a could be the way to the near future artificial light devices. The apart performances of the CFL electronic ballast and the s when brought together could lead to a high-performance, low cost, low energy consumption lighting bulb. ACKNOWGMENT This paper was supported by the project "Doctoral studies in engineering sciences for developing the knowledge based society-sidoc contract no. POSDRU/88/.5/S/60078 project co-funded from European Social Fund through Sectorial Operational Program Human Resources Fig. 4. Waveforms of (reversed zener diode) and voltage. BIBLIOGRAPHY. A. Houri, P. Khoury, Financial and energy impacts of compact fluorescent light bulbs in a rural setting, Elsevier Energy and Buildings 4, p658 p666, 00.. T. Welz, R. Hischier, L.M. Hilty, Environmental impacts of lighting technologies Life cycle assessment and sensitivity analysis, Elsevier Environmental Impact Assessment Review 3, , 0 3. P. Bertoldi, Residential Lighting Consumption and Saving Potential in the Enlarged EU, European Commission DG JRC, Paris, 6 February K. den Daas, Philips: Lighting:Building the future, New York, March 5, N. Khan, N. Abas, Comparative study of energy saving light sources, Renewable and Sustainable Energy Reviews 5, , M. Cervi, A.R Seidel, F.E. Bisogno, Fluorescent Lamp Model Based on the Equivalent Resistance Variation 00, 37th IAS Annual Meeting vol., E.D. Edward, Negative incremental impedance of fluorescent lamps California Institute of Technology, L. Yu, J. Yang, The Topologies of White Lamps' Power Drivers, 3rd International Conference on Power Electronics Systems and Applications, E. Mineiro Sá Jr., C.S. Postiglione, F.L.M. Antunes, A.J. Perin, Low Cost ZVS PFC Driver for Power s, IEEE, Chao-Lung Kuo, Tsorng-Juu Liang, Kai-Hui Chen, Jiann-Fuh Che, Design and Implementation of High FrequencyAC- Driver with Digital Dimming, IEEE, 00 Petre-Dorel TEODOSESCU Mircea BOJAN Dr. Ioana-Cornelia VESE Prof. Richard MARSCHALKO Technical University of Cluj Napoca Department of Electrical Engineering Cluj-Napoca Memorandumului Street, No.8, Romania Tel.: Fax.: Petre-Dorel TEODOSESCU, (98), graduated in electrical engineering (007), PHD student since 009, 5 months Research Fellowship in optoelectronics al University of Liverpool (00-0), scientific paper in Romania, book chapters. Field of interest Electronics, optoelectronics and power electronics. Petre.Teodosescu@edr.utcluj.ro

7 Volume 53, Number 3, 0 4 Mircea BOJAN, (977), graduated in electrical engineering (000), and advanced studies in automation of electrical drives with energy performances (00). At the moment is teaching assistant, (004), at the Technical University of Cluj, Romania, book, 8 scientific papers in Romania, abroad, 4 R&D projects in the domain of electronics and power electronics. Field of interest: Line-friendly PWM AC-to DC converters, Power Factor Control, and line-conditioning strategies. Mircea.Bojan@edr.utcluj.ro Ioana-Cornelia VESE received the Dipl.-Ing degree in Electrical Engineering in 003 and the Ph.D degree in 00 from the Technical University of Cluj-Napoca, Cluj-Napoca, Romania, where she is ly working as Assistant Lecturer with the Department of Electric Machines and Drives. Her research interests include design and control strategies of electric motors, multiphysics computer-aided analysis by finite elements and linear tubular electric actuators. She is author and co-author of 8 published scientific papers in refereed technical journals and international conference and symposium proceedings. ioana.vese@edr.utcluj.ro Dr. Richard MARSCHALKO (95), graduated in electromechanical engineering (976), doctoral degree (989) Alexander von Humboldt scholarship (99-99, 996, 999). At the moment is with the Technical University Cluj, Romania, professor (998), 8 books, 58 scientific papers in Romania, 8 abroad, 3 romanian national patents, 3 R&D projects in the domain of electrical drives, power electronics and electronics. PhD supervisor. richard.marschalko@edr.utcluj.ro.