PONTIFÍCIA UNIVERSIDADE CATÓLICA
DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICA
Programa de Pós-Graduação em Engenharia Elétrica
MULTIFREQUENCY ELECTRONIC BALLAST
FOR T5 FLUORESCENT LAMPS
WITH VOLTAGE-PREHEATING
Authors: Anderson Soares
Fernado S. dos Reis
Marcelo Toss
Reinaldo
Tonkoski
PONTIFÍCIA UNIVERSIDADE CATÓLICA
DO RIO GRANDE DO SUL
DEPARTAMENTO DE ENGENHARIA ELÉTRICA
Programa de Pós-Graduação em Engenharia Elétrica
Multifrequency Electronic Ballast for T5 Fluorescent lamps with
Voltage-Preheating
1.Introduction
2.T5 fluorescent lamps, characteristics
3.Proposed topology
4.Design procedure
5.Simulation results
6.Experimental results
7.Rapid cycle test for T5 fluorescent lamps
8.Discussion
9.Conclusion
10.References
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PONTIFÍCIA UNIVERSIDADE CATÓLICA
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DEPARTAMENTO DE ENGENHARIA ELÉTRICA
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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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2. T5 FLUORESCENT LAMPS – Characteristics
T5
T8
T10
T12
• 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;
Fig. 01 – Fluorescent lamps, evolution.
• Constant lumen level during lamp life (92% at 10.000 hours);
• High frequency operation (no flicker);
• More expensive (approximately 2.5 x T8);
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DEPARTAMENTO DE ENGENHARIA ELÉTRICA
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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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3.
PROPOSED TOPOLOGY
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
Disadvantages:
• The filaments are placed inside the LC
resonant filter, resulting in excessive lamp
voltage during preheating and excessive
filament current during runtime [2].
S1
+
Cs
-
L
Drive
S2
Lamp
E
Fig. 02 – Circuit diagram of a conventional
series-resonant parallel load electronic ballast.
Cp
• After lamp ignition, the filament power
consumes about 0,5W for each filament.
Advantages:
• Simple configuration;
• High Efficiency.
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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.
S1
L2:3
C1
+
-
DRIVE
L1
C3
L2:1
C2
LAMP
E
S2
S3
L2:2
Fig. 03 – Topology of proposed ballast based on a voltage source filament.
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.
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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.
S1
L2:3
C1
+
-
Drive
L1
C3
L2:1
C2
L AMP
E
S2
S3
Fig. 05 – Warm up, start up and steady state frequency range.
L2:2
Fig. 04 – Topology of proposed ballast.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA
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5. SIMULATION RESULTS
Some simulations were carried out in order to verify the behavior of the
proposed ballast under preheating, startup and steady state operation.
U5 3m
1
21
V1G1
V1 = -15
V2 = 15
TD = 11.5u
TR = 1u
TF = 1u
PW = 11.5u
PER = 25u
S1
IRF830
U6 3m
2
V2G1
V1 = -15
V2 = 15
TD = 5.25u
TR = 1u
TF = 1u
PW = 5.25u
PER = 12.5u
D2
R4
0.1
CS
R3
LS
1
2
1
0.1
100n
C3
26.4n
U1
E
U3 3m
400Vdc
1
2
R2
0.1
S2
21
1
4.41mH
IRF830
3.2m
U2
2
3.2m
L2
CP
U4 3m
V1G2
V1 = 15
V2 = -15
TD = 11.5u
TR = 1u
TF = 1u
PW = 11.5u
PER = 25u
2
2.4m
V2G2
V1 = 15
V2 = -15
TD = 5.25u
TR = 1u
TF = 1u
PW = 5.25u
PER = 12.5u
3.2u
3.99n
RFx
15
R5
0.1
RP
RLAMP
9960
996
1
0
U7 3m
2
0
Fig. 06 – Simulation circuit, Orcad Software.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA
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DEPARTAMENTO DE ENGENHARIA ELÉTRICA
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5. SIMULATION RESULTS
20V
Preheating
Startup
Steady state
Filament Voltage
10V
VRMS= 7,6V
0V
-10V
-20V
2.0ms
V(L2:3)
2.0KV
2.5ms
3.0ms
3.5ms
4.0ms
Time
Ignition lamp voltage
VPICO= 1800V
0V
-2.0KV
2.0ms
V(LS:2)
2.5ms
3.0ms
Time
3.5ms
4.0ms
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6.
EXPERIMENTAL RESULTS
Preheating Frequency
f PH 
1
1.38R1  75C1
Run Frequency
( 06 )
f RUN 
1
1.38R1  75C1  C2 
Fig. 08 – Prototype circuit of the proposed electronic ballast.
( 07 )
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6.
EXPERIMENTAL RESULTS
EMI Filter
Boost Switch
Boost
CI
Drive
Switch
Boost
Inductor
Drive
CI
Fig. 09 – Prototype board of the proposed electronic ballast.
Startup
Inductor
Switch
Inductor
Preheating
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6.
EXPERIMENTAL RESULTS
Filament (CH2) and lamp Voltage (CH1)
 
Measured:
Lamp voltage during start up VLAMP= 2,04 kVPICO
Specified:
Minimum lamp voltage VLAMP= 750VPICO
 
 
Preheating time 2s
1 ) V L:
2 ) V F:
 
50 0 V o lt 5 00 ms
1 0 V o lt 50 0 ms
Measured: Lamp voltage VLAMP= 55VRMS
Specified: Maximum lamp voltage= 240VRMS
 
Measured: Filament voltage VRF= 7,5VRMS
Specified: Minimum= 6,0V e Maximum= 7,9VRMS
 
1 ) V L:
2 ) V F:
10 0 V o lt 1 0 u s
5 Vo l t 1 0 u s
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6.
EXPERIMENTAL RESULTS
Lamp voltage vs. lamp current
ILAMP = 0,175A (nominal value ILAMP = 0,170A)
VLAMP = 178V (nominal value VLAMP = 167V)
  
 
1 ) V L: 10 0 V o lt 5 us
2 ) IL: 20 0 mA 5 u s
Table I
* Electrical measurements 28W/T5 with Power Analysis System Xitron 2572R .
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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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7.
RAPID CYCLE TEST FOR T5 FLUORESCENT LAMPS
Fluorescent lamp lifetime is determined by the loss of the electronemitting 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
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.
Fig. 12 – “A” Manufacturer lamp resistance (%)
versus time (min).
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].
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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.
Table II
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8.
DISCUSSION
 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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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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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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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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