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Proiect cofinanţat din Fondul Social European prin Programul Operaţional Sectorial pentru Dezvoltarea Resurselor Umane 2007 –
2013
Axa prioritară 1: "Educaţia şi formarea profesională în sprijinul creşterii economice şi dezvoltării societăţii bazate pe cunoaştere"
Domeniul major de intervenţie 1.5: "Programe doctorale şi post-doctorale în sprijinul cercetării"
Titlul proiectului: "Studii doctorale în ştiinţe inginereşti în scopul dezvoltării societăţii bazate pe cunoaştere - SIDOC"
Cod contract: POSDRU/88/1.5/S/60078
Beneficiar: Universitatea Tehnică din Cluj-Napoca
Faculty of Electrical Engineering Ing. Teodosescu Petre Dorel
PHD THESIS
-Summary-
RESEARCH CONCERNING THE DEVELOPMENT OF
ELECTRONIC BALLAST WITH POWER FACTOR
CORRECTION
Scientific Advisor,
Prof. Dr. Ing. Richard MARSCHALKO
2012
1
Phd Thesis Contents
1.Introduction ...............................................................................................................................................................................................2
2. Current status in control circuits and electronic control of lighting systems ............................................................................................2
2.1. Present status in fluorescent lighting systems ....................................................................................... Error! Bookmark not defined.
2.2. Artificial lighting with light emitting diode (LED .................................................................................................................................2
2.3. The problem of power factor lighting with CFL and LED lighting systems ..........................................................................................2
2.4. Preliminary conclusions and research lines............................................................................................................................................3
3.Studies and research on the development of compact fluorescent lighting systems...................................................................................3
3.1. Investigation by mathematical modeling, simulation and performance testing of the compact fluorescent lamps (CFL) on the market3
3.2. Power factor correction and input current shape using passive filters................................................... Error! Bookmark not defined.
3.3. Active power factor correction methods for CFL lamps .......................................................................................................................3
3.4. General conclusions regarding the proposed solutions for the correction of the power factor for compact fluorescent lamps ..............4
4. Theoretical and experimental research on new power supply and control circuits for LED lighting systems...........................................5
4.1. LC and LLC resonant converters ...........................................................................................................................................................5
4.2.The reconfiguration of an electronic ballast into a resonant converter....................................................................................................5
4.3. Implementation and testing of a LED lighting device using self-oscillating resonant converters ..........................................................5
5. General conclusions..................................................................................................................................................................................5
List of contributions.................................................................................................................................................................................. 155
1. Introduction
Modern lighting systems are based on the transformation of electrical energy into light energy. In the artificial lighting devices
field of research, the objectives are the continuous improvement of their performance, such as the light efficiency W/lm as well as the
reliability, life service, cost of implementation, complexity, quality of the generated light, flexibility in the use for different applications,
reduced size and weight, wide range of working temperatures, power factor, total harmonic distortion factor, electromagnetic
compatibility criteria and EMI.
Electronic lamps with Edison base, CFL and LED, are considered low power loads, therefore the issues regarding the power
factor could be easily overlooked by the user, manufacturer or electricity distributor, especially in the case of a lack of clear regulations.
If the negative effects brought about by an electronic lamp with poor power factor are negligible, when analyzing the global effects of a
large number of such devices, the analysis and correction of power factor is appropriate and necessary.
Thus, the research in this thesis will be mainly oriented towards the power factor correction for the electronically controlled
lighting systems and new solutions that can be , directly implemented are being investigated.
Additionally, the high power light emitting diodes (LED) is one of the fastest growing segments of worldwide research. The
research pathways pursued in this thesis are based on solutions to improve power supply unit through a CFL-LED unified technology
that is relatively simple, cheap and easy to implement on a large scale.
2. Present status in control circuits and electronic control of lighting systems
The second chapter of the thesis presents the current state of the technology, special features, advantages and disadvantages of
the electronic lighting system with CFL and LED. Following analysis, the appropriate research pathways are being outlined, namely, the
power factor correction for lighting systems and the development of new LED electronic control circuit based on CFL-LED common
technology, that can be implemented with lower investment and is distinguished by a lower complexity than the current solutions.
2.1 Present status in fluorescent lighting systems
This section refers especially to the artificial lighting devices that are intended to be the most appropriate solution to replace
the existing incandescent lamps with Edison type socket, namely the compact fluorescent lamps. Regarding these lighting devices, we
will highlight some ideas about the technology as well as the operating principles. The CFL shape and size are similar to those of the
incandescent lamps in order to be compatible with the existing fixtures. Furthermore, some real models of electronic circuits found in
such lamps are being described. This lighting device, especially the electronic ballast in the structure, is the main element in the research
to be conducted in this thesis.
Following the practical analysis of a number of ballasts used in compact fluorescent lamps, manufactured by well-known
companies, it can be concluded that the operating principles and circuits are relatively similar. All these are based on self-oscillating halfbridge inverter topology with discrete electronic components.
2.2. Artificial lighting with light emitting diode (LED)
This chapter analyzes the principle of artificial lighting using light emitting diodes (LED). The thesis outlines the operating
principles of these types of diodes as well as the electronic command and control topologies. The circuits mainly operate on classic
Buck, Boost or Flyback converters.
These classical topologies LED control circuits also have some disadvantages such as:
1. High complexity
2. The use of a specialized integrated circuit increases the production cost
3. The closed loop operation increases the number of components used
Thus, in this thesis, we shall try to eliminate or at least minimize these disadvantages by designing, simulating and
experimenting with new circuits for constant current control of LEDs.
2
2.3. The problem of power factor lighting with CFL and LED lighting systems
The CFL and LED lighting devices are considered to be low power loads, often below 30W. This makes the electronic
lighting systems not to be severely and very explicitly regulated in terms of power factor and harmonic levels. In this context, this
chapter, very briefly restates the power factor issue in general and illustrates the main passive and active solutions for power factor
correction, that could be possibly applied for these types of nonlinear loads.
2.4. Preliminary conclusions and research lines
The CFL and LED lighting systems appear to be the future solution for energy consumption efficiency at the expense of the
traditional solution, that is the incandescent lamp. The two features have clear advantages, for instance low power consumption and long
life, but also present certain difficulties in obtaining a low implementation cost; moreover, the power grid behavior can no longer be
ignored, but must be reviewed and the best solutions to implement circuits for power factor correction need to be found.
3. Studies and research on the development of compact fluorescent lighting systems
The third chapter of the thesis deals with the mathematical model of the ideal electronic ballast, followed by the modeling,
simulation and testing of practical circuits meant to correct the poor power factor of the CFLs. Both passive and active methods are
being investigated, and finally a comparative study is being conducted, based upon the results obtained in the case of each proposed
solution.
3.1. Investigation by mathematical modeling, simulation and performance testing of the compact fluorescent lamps (CFL) on the
market
Four circuits found in the CFL lamps are being analyzed, and the general conclusion, very important in the background of this
research, would be that the inverter topology is the same for each of the models, as this solution represents the ideal compromise between
cost production, efficiency and satisfactory working life. Accordingly, the research on improving the power factor of CFLs should be
made in such manner that the mature part of the circuit to be affected as little as possible.
The ideal mathematical model for a CFL ballast is being introduced; this development is appropriate for the foundation of a
systemic analysis, by comparison with the products found on the market and for the recognition of the advancement directions of CFL,
like the improvement of the power factor and the input current shape.
3.2. Power factor correction and input current shape using passive filters
The application of passive power factor correction methods (Fig. 1) through passive filters is possible, with certain advantages
such as low implementation cost, reduced complexity and reduced number of electronic components. The analysis performed also
highlights some disadvantages, for instance high crest factor for the current through the fluorescent tube, more electrolytic capacitors
compared with the original circuit and a slightly higher production price. The major advantage of this method is the small size of
electronic circuits necessary and the practically perfect compatibility with the Edison type enclosure.
a)
b)
c)
Fig. 1 Valley-Fill implementation results; a) Electronic schematics for the 3 models;
b) Input current (yellow) and voltage (blue); Fourier analyses of the input current (green); c) Tube current ripple.
3
3.3. Active power factor correction methods for CFL lamps
The main purpose of this chapter is to improve the performance of the compact fluorescent lamps, in terms of AC mains
behavior, without significantly influencing the good performance already achieved, such as the reliability, performance or production
cost.
In addition, this chapter depicts three possible solutions for active power factor correction through the implementation of preconverters with IC Boost PFC, simple Boost and simple Buck-Boost (Fig.2) topologies and the results are very suggestively represented
in Table 1.
Input voltage (blue) and current (yellow)
Input current (yellow) and FFT (green)
Tube voltage (blue) and current (yellow)
Fig. 2. The schematics and the results of the Buck-boost PFC pre-converter implementation on a CFL electronic ballast.
3.4. General conclusions regarding the proposed solutions for the correction of the power factor for compact fluorescent lamps
No.
1
2
3
4
5
Table 1 illustrates the overall results using the proposed solutions to correct the power factor for CFL:
PFC
Fitting
Circuit
Input
Input
Tube
Tube
Power THD
Tube
Voltage Current Voltage Current factor
current Circuit Edison
enclosure
Crest
Factor
V
A
V
mA
%
Original
Circuit
220V
54mA
78
140
0.6
79.4%
1.5
(Experimental
+ Simulation
Results)
Valley fill 1
(Experimental 220V
45mA
70
129
0.87
30.56% 1.76
Passive
Easy
+ Simulation
Filter
Results)
Valley fill 2
(Experimental 220V
48mA
74
129
0.90
22.86% 1.8
Passive
Easy
+ Simulation
Filter
Results)
Valley fill 3
(Experimental 220V
50mA
74.4
134
0.82
46.53% 1.66
Passive
Easy
+ Simulation
Filter
Results)
Boost ASIC
Active
PFC
control
preconverter
77V
156mA
77.3
134
0.97
8.46%
1.23
Closed Not easy
(Experimental
loop
+ Simulation
Results)
4
Total
Electric
Efficiency
Cost
Euro
91.9%
-
91.2%
0.23
90.3%
0.23
90.5%
0.06
86.58%
4.76
6
7
Boost
PFC
preconverter
(Simulation
results)
Buck-Boost
PFC
preconverter
(Experimental
+ Simulation
Results)
77V
155mA
74.5
131
0.96
10.93%
1.25
220V
52.5mA
77.3
127
0.99
2.18%
1.43
Active
control
OpenLoop
Active
control
OpenLoop
Easy
81.8%
2.09
Easy
84.9%
2.09
Table 1. Overall results obtained with passive and active power factor correction methods
Due to the fact that the output voltage in the Boost topology is significantly higher than the input voltage, the best PFC
solution for the most common configuration of CFL ballast is the Buck-Boost PFC. This is mainly because this solution appears to be the
best compromise between the ability to correct the power factor, THD, implementation cost, crest factor, complexity and efficiency.
4. Theoretical and experimental research on new power supply and control circuits for LED lighting systems
In the fourth chapter a study on the possible reconfiguration of an electronic CFL ballast, for controlling LED with constant
current is being presented. A mathematical model is being developed, followed later by the modeling and Orcad / PSpice simulation of
the proposed solution. Finally, two LED lamps, 4W, 8W respectively, are being implemented, where the constant current control is
achieved through an reconfigured CFL ballast as a LC parallel resonant, half-bridge converter.
4.1. LC and LLC resonant converters
This chapter presents the summary and general characteristics of the LLC and LC resonant converters. These converters have
not been considered as a possible option in converters for electronic lighting systems up until it was shown that they can have a very high
efficiency even in comparison with acknowledged circuits.
4.2. The reconfiguration of an electronic ballast into a resonant converter
In this section we present, by means of analytical and Orcad/ Pspice modeling, the operating principle of the series and
parallel LC resonant converters. Following the theoretical analysis, two real models of resonant converters are being introduced, made
from reconfiguring an electronic ballast, initially used in the CFL lighting devices. The proposed models (Fig. 3) consist of, quasiresonant half-bridge CFL inverter topology, completed with a high frequency rectifier circuit and the load composed of the electrical
equivalent circuit of an LED. These assumptions will be analyzed by mathematical modeling and simulation using Orcad / PSpice.
Fig. 3. The schematics of the reconfigured CFL electronic ballast to work as a constant current LED drive
4.3. Implementation and testing of a LED lighting device using self-oscillating resonant converters
Finally, we present the practical implementation of a LED control circuit using an electronic ballast in self-oscillating halfbridge configuration found in the CFL, (Fig.4). Thus, we present two LED lamps, 4W and 8W. The 4W lamp is made with the electronic
ballast found in Philips Genie 11W CFL lamps, redesigned to control a 12V LED BRIDGELUX. The 8W lamp will be implemented
using the same ballast, but this time the load will be represented by 3, 12V LED BRIDGELUX in series.
5
Fig. 4.Waveforms of the current (yellow) and voltage (blue) at the LED level for the two 4W and 8W LED lamps.
5. General conclusions
The thesis introduces practical solutions needed to solve current problems of the Edison type electronic lighting. Thus, in this
paper several methods for power factor correction are being proposed, and the analysis of these is conducted by means of both simulation
and practical implementation. Furthermore, new constant current control circuits for LED are being developed, while the solutions are
primarily demonstrated analytically and then implemented in practice.
List of contributions
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Study on the technology of the electronic ballasts found in the compact fluorescent lamps.
Implementation of Orcad / PSpice models for two electronic ballasts found in the compact fluorescent lamps.
Experimental analysis of the working principle for the four models of CFL by identifying the input parameters and
behavior towards the public grid.
Harmonic analysis in Orcad / PSpice input current for two models of electronic ballasts.
Practical implementation and Orcad / PSpice simulations of the Valley Fill passive filters for power factor correction
applied on the self oscillation CFL electronic ballast.
Practical implementation and Orcad / PSpice simulations for an self-oscillating electronic ballast with active power
factor correction by the implementation of a boost pre-converter. The pre-converter is operating in closed loop and was
built around a specialized integrated circuit (L6562) for PFC function.
Analysis by Orcad / PSpice simulations for the PFC boost pre-converter with simple open-loop control.
Practical analysis and Orcad / PSpice simulations of the power factor correction circuit in buck-boost configuration for
the CFL electronic ballast.
Comparative analysis of the active power factor correction methods for the CFL ballasts with self oscillation control.
Technologies used were: boost topology with specialized integrated circuit, open-loop boost and buck-boost topologies
with simple 555 circuit controls.
The ideal electronic ballast modeling to allow a more detailed analysis of the operation principle.
Reconfiguring of the CFL self oscillation electronic ballast to function as a resonant converter.
Building the Bode diagrams for the parallel and series LC resonant tanks based on the components found in the CFL
electronic ballast.
Transient analysis of electronic ballast found in the CFL and reconfigured to work as constant current source for the light
emitting diodes (LED).
Analysis by Orcad / PSpice simulations of the reconfigured electronic ballasts circuits to control the LEDs.
Comparative analytical and Orcad / PSpice simulations for the real and ideal electronic ballasts models, reconfigured
for controlling LEDs.
Practical implementation of two original LED control circuits (4W and 8W) obtained by reconfiguring a electronic
ballast found in the CFL.
6