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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
MULTIFREQUENCY ELECTRONIC MULTIFREQUENCY ELECTRONIC
BALLAST FOR T5 FLUORESCENT LAMPS BALLAST FOR T5 FLUORESCENT LAMPS
WITH VOLTAGE-PREHEATINGWITH VOLTAGE-PREHEATING
Authors: Anderson Soares Fernado S. dos Reis
Marcelo Toss Reinaldo
Tonkoski
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
Multifrequency Electronic Ballast for T5 Fluorescent lamps with Voltage-Preheating
1.Introduction2.T5 fluorescent lamps, characteristics3.Proposed topology4.Design procedure5.Simulation results6.Experimental results7.Rapid cycle test for T5 fluorescent lamps8.Discussion9.Conclusion10.References
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
1.INTRODUCTION
In the last years, it have had an evolution in use of the more efficient illuminating systems, as example: to substitute fluorescent lamps by incandescent lamps, the use of electronic ballast in place of magnetic ballast, the use of more efficient fixtures and lamps.
Hanover Fair in 1995, great European manufacturers had presented the T5 a new fluorescent lamp with less diameter, shorter, more efficient and developed for to be successor of T8 [1].
This work presents analysis, development of an electronic ballast with voltage preheating for one 28W/T5 fluorescent lamp and rapid cycle test to determine the rated lifetime of lamp with the proposed electronic ballast.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
2. T5 FLUORESCENT LAMPS – Characteristics
• Less diameter 16mm (T5) to 26mm (T8), 40%;
• Less lengths 1149mm(28W) to 1200mm(32W);
• Lamp efficacy up to 104 lm/W (10% compared T8);
• Maximum light output at 35 °C (25 °C T8);
• Low mercury dose;
• Constant lumen level during lamp life (92% at 10.000 hours);
• High frequency operation (no flicker);
• More expensive (approximately 2.5 x T8);4
T5 T8 T10 T12
Fig. 01 – Fluorescent lamps, evolution.
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
2. T5 FLUORESCENT LAMPS– Characteristics
For a long lifetime and a stable light output, the electronic ballast should fulfill the strict requirements for preheating and steady state operation, as following [2]:
Preheating Operation• The filament should be first heated to an optimum temperature (about
1000K). • During filament preheating, the voltage across the lamp should be kept as
low as possible. • Only after the filament’s optimum temperature is reached, the voltage of the
lamp should rise to the ignition level.
Steady State Operation• Once the lamp is ignited, the ballast should behave as a current source to
ensure stable operation. • The crest factor of the lamp’s current should not exceed 1.7.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
3. PROPOSED TOPOLOGY
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Selection of a preheating method depends on the types of filaments and on time available for ignition lamps [3]. Two fundamentally different drivers could be used for filament preheating [2][3]: a current source or a voltage source.
A.Current Source Filament Preheating
C p
L
Lam
p
S 2
C s
S 1
D r ive
E +
-
Disadvantages:
• The filaments are placed inside the LC resonant filter, resulting in excessive lamp voltage during preheating and excessive filament current during runtime [2].
• After lamp ignition, the filament power consumes about 0,5W for each filament.
Advantages:• Simple configuration;• High Efficiency.Fig. 02 – Circuit diagram of a conventional
series-resonant parallel load electronic ballast.
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
Fig. 03 – Topology of proposed ballast based on a voltage source filament.
L 1
L A
M P
S 2
C 2
C 1
S 1
D R IV E
E +
-
L 2 :1
L 2 :3
L 2 :2
C 3
S 3
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3. PROPOSED TOPOLOGY
B.Voltage Source Filament Preheating
An alternative approach for eliminate the disadvantage of this topology, Fig. 03 presents an alternative method to achieve a voltage filament preheating.
Advantages:• The two resonant filters provide sufficient decoupling between the preheating and the steady state operation, so that each may be designed for optimum performance.• The lamp may be started up without the adverse effects on the lamp lifetime. • The filaments power is eliminated after the preheating time, increasing system efficiency.
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
Fig. 04 – Topology of proposed ballast.
Fig. 05 – Warm up, start up and steady state frequency range.
L A
MP
Drive
L 1
S 2
C 2
C 1
S 1
E +
-
L 2 :1
L 2 :3
L 2 :2
C 3
S 3
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3. PROPOSED TOPOLOGY
The drive works in two different frequencies (fPH and fRUN). During preheating operation, the secondary windings (L2:2; L2:3) supply the filaments and the LC series C parallel filter keeps the low voltage across the lamp. After this period the frequency changes to the RUN frequency and a high voltage is applied to capacitor C2 providing the necessary voltage for lamp ignition.
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
5.SIMULATION RESULTSSome simulations were carried out in order to verify the behavior of the
proposed ballast under preheating, startup and steady state operation.
Fig. 06 – Simulation circuit, Orcad Software.0
0
U5 3m1 2
RFx15
E
400Vdc
R3
0.1
L2
2.4m 3.2u RLAMP
996
S1IRF830
D2
LS
4.41mH
1 2
V2G2
TD = 5.25u
TF = 1uPW = 5.25uPER = 12.5u
V1 = 15
TR = 1u
V2 = -15
U1
3.2m
1
2
R40.1
V2G1
TD = 5.25u
TF = 1uPW = 5.25uPER = 12.5u
V1 = -15
TR = 1u
V2 = 15
U3 3m
1 2
RP
9960
V1G1
TD = 11.5u
TF = 1uPW = 11.5uPER = 25u
V1 = -15
TR = 1u
V2 = 15
CS
100n
R20.1
CP
3.99n
S2
IRF830
C326.4n
U2
3.2m
1
2
V1G2
TD = 11.5u
TF = 1uPW = 11.5uPER = 25u
V1 = 15
TR = 1u
V2 = -15
R50.1
U4 3m
1
2
U6 3m
1
2
U7 3m
1
2
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
Time
2.0ms 2.5ms 3.0ms 3.5ms 4.0msV(L2:3)
-20V
-10V
0V
10V
20V
Time
2.0ms 2.5ms 3.0ms 3.5ms 4.0msV(LS:2)
-2.0KV
0V
2.0KV
Filament Voltage
VRMS= 7,6V
Ignition lamp voltage
VPICO= 1800V
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5.SIMULATION RESULTS
Preheating Startup Steady state
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
6. EXPERIMENTAL RESULTS
Fig. 08 – Prototype circuit of the proposed electronic ballast.
175138.1
1
CRfPH
Preheating Frequency
2175138.1
1
CCRfRUN
Run Frequency
( 06 ) ( 07 )
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
EMI Filter
Switch Inductor Preheating
Drive CI
DriveSwitch
Boost CI
BoostInductor
Boost Switch
StartupInductor
12Fig. 09 – Prototype board of the proposed electronic ballast.
6. EXPERIMENTAL RESULTS
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
Filament (CH2) and lamp Voltage (CH1)
1) VL: 500 Volt 500 ms 2) VF: 10 Volt 500 ms
1) VL: 100 Volt 10 us 2) VF: 5 Volt 10 us
Measured: Lamp voltage VLAMP= 55VRMS
Specified: Maximum lamp voltage= 240VRMS
Measured: Filament voltage VRF= 7,5VRMS
Specified: Minimum= 6,0V e Maximum= 7,9VRMS
Measured:Lamp voltage during start up VLAMP= 2,04 kVPICO
Specified:Minimum lamp voltage VLAMP= 750VPICO
Preheating time 2s
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6. EXPERIMENTAL RESULTS
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
Lamp voltage vs. lamp current
ILAMP = 0,175A (nominal value ILAMP = 0,170A)
VLAMP = 178V (nominal value VLAMP = 167V)
1) VL: 100 Volt 5 us 2) IL: 200 mA 5 us
Table I
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6. EXPERIMENTAL RESULTS
* Electrical measurements 28W/T5 with Power Analysis System Xitron 2572R .
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
7. RAPID CYCLE TEST FOR T5 FLUORESCENT LAMPS
To determinate the rated average lifetime of fluorescent lamps, the Illuminating Engineering Society of North America (IESNA) specifies a test method using a large sample of lamps.
This method consists of burning cycles, at which the lamps remain ON during 3 hours and OFF during 20 minutes. This method may take up to 3 years to get results for a specific lamp and ballast.
Recently, rapid cycle methods, intended to reduce this testing time have been published [6].
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
Fluorescent lamp lifetime is determined by the loss of the electron-emitting coating on the electrodes. Electrode temperature directly affects the evaporation and erosion of the emitting material, therefore affecting the lamp lifetime. Since electrode temperature is hard to measure directly, electrode resistance may be used as a related parameter [4] and [7].
A method proposed in [6] establishes the OFF time for rapid cycle test for T8 and compact fluorescent lamps, based in the measurement of the electrode resistance change after power extinguishes in the lamp.
The same analysis will be applied in this work to define the appropriate OFF time for rapid cycle test for T5 fluorescent lamp.
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7. RAPID CYCLE TEST FOR T5 FLUORESCENT LAMPS
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
From three of the major lamp manufacturers, two 28W/T5 fluorescent lamps were randomly selected and measured from each manufacturer. The results obtained for the three lamp companies were basically the same.
These results demonstrate that, for any rapid test cycles, if the lamp OFF time is less than 5 minutes, the electrode does not cool completely.
This reduces the damage to the electrode during lamp starting, and will probably result in overestimation of the rated average lifetime [6].
Fig. 12 – “A” Manufacturer lamp resistance (%) versus time (min).
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7. RAPID CYCLE TEST FOR T5 FLUORESCENT LAMPS
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
8. DISCUSSION
To verify the compatibility between proposed electronic ballast and T5 lamp, two cycle tests were made with three different ballasts:
Cycle tests:• Cycle time used by ballast manufacturer (30s ON and 30s OFF);• Cycle time found on the cooled filament (30s ON and 5min OFF); Electronic ballasts:• Electronic ballast with voltage preheat, as proposed;• Electronic ballast without preheating;• Commercial electronic ballast found in Brazilian market, without preheating.
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Table II
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
The first rapid cycle test was conclude after 40 days. The rapid cycle test used by ballast manufacturer determines a minimum number of cycles until the lamp failure.
As an example, in the most common commercial application the lamp is turned ON and OFF two times in 12 hours, so the minimum expected number of cycle within this period is 3300. Therefore, only the electronic ballast proposed should be approved.
The second rapid cycle test was concluded after 70 days. The lamp manufacturer specifies a lifetime 20000 cycles to rapid cycle test with 30s ON and 4.5 min. OFF. In this situation, only the electronic ballast proposed should be approved.
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8. DISCUSSION
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
9. CONCLUSION
The proposed multifrequency electronic ballast topology provides a highly controlled preheating process. The filaments are fed by a voltage source with tight tolerance, while the lamp voltage during the preheating period is very low.
The circuit was analyzed, simulated and experimentally tested, and the results support the validity of the model developed in this paper.
The filaments’ power is eliminated after the preheating time, increasing system efficiency.
The rapid cycle test point out the importance of the preheating circuit in the T5 lamp lifetime. Therefore, the electronic ballast proposed is an excellent choice for T5 fluorescent lamps.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
9. CONCLUSION
In November 2004 was published in DIÁRIO DA UNIÃO, number 217, part 188, references to Brazilian electronic ballast standards NBR14417 and NBR14418, specifies to T5 fluorescent lamp.
Electronic ballast for T5 fluorescent lamp without preheating, instant start type, can’t be manufacture, import or market.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICAPrograma de Pós-Graduação em Engenharia Elétrica
10. REFERENCES
[1] “Ultra-Slim Design With Extraordinary Light Output, SILHOUETTE T5”, Philips Lighting Company, September 2001. [2] Ben-Yaakov, S.; Shvartsas, M.; Ivensky, G., “HF Multiresonant Electronic Ballast for Fluorescent Lamps with Constant Filament Preheat Voltage”, IEEE Transactions on Power Electronics, 2000.[3] T.-F. Wu; C.-C. Chen; J.-N. Wu, “An Electronic Ballast with Inductively Coupled Preheating Circuits,” IEEE Transactions on Power Electronics, 2001.[4] Chin S. Moo; Tsai F. Lin; Hung L. Cheng; Ming J. Soong, “Electronic Ballast for Programmed Rapid-Start Fluorescent Lamps,” IEEE Transactions on Power Electronics, 2001.[5] Do Prado, N. R.; Seidel, R.A.; Bisogno, E. F.; Costa, D. A. M., “Self-Oscillating Electronic Ballast Design”, IV Conferência de Aplicações Industriais – Induscon2000, Porto Alegre, Rio Grande do Sul, Novembro 2000.[6] Davis, R.; Yufen, J.; Weihong, C., “Rapid-cycle testing for fluorescent lamps: What do the results mean?”, Annual Conference of the Illuminating Engineering Society of North America, 1996.[7] Klien D., “A New Concept for Fluorescent Lamp Ballasts,” IEEE Transactions on Power Electronics, 2000.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SULPONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL