IEEE ISIE 2005, June 20-23, 2005, Dubrovnik, Croatia /05/$ IEEE 423

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1 IEEE ISIE 2005, June 20-23, 2005, Dubrovnik, Croatia Design of an Adaptive Electronic Starter for Fluorescent Lamps Chuan-Sheng Liu*, Liang-Rui Chen*, Neng-Yi Chu*, Jieh-La Jaw** *National Formosa University / Department of Aeronautical Engineering **Chienkuo Technology University / Department of Electronic Engineering Abstract A cost competitive circuit of a fluorescent lamp electronic starter that can provide a single-pulse ignition, adaptive preheating time, fast reset and lower voltage working ability is proposed in this paper. In order to analyze the proposed electronic starter, circuit topologies in each working state are derived. A prototype for 20W fluorescent lamps is also designed and implemented to access the performance. Experimental results show that features of a single-pulse ignition, adaptive preheating time, fast reset and lower voltage working ability can be achieved what we have predicted. Keyword: Fluorescent lamps, Electronic starter I. INTRODUCTION Although electronic ballasts have many benefits, such as high efficiency, high power factor, and low light fluctuation, the cost is rather high [1-5]. Therefore, in the present situation, the magnetic ballast in existing installation remains to be used. Fig. 1 shows that the standard topology of the fluorescent lamp, the magnetic ballast and the starter. starter is shortened for a constant time to make a current flow through the lamp filaments for preheating them to a temperature that they easily emit electrons. The starter is opened and then the energy stored in the magnetic ballast is converted into a high surge voltage that causes the breakdown of the lamp gas. If the temperature and the surge voltage are high enough, the fluorescent lamp will be lit up. After fluorescent lamp is lit up, the magnetic ballast would be used to maintain a stable current flowing through the fluorescent lamp to make sure of an unfaltering luminance. One type of the commonly used starters is the glow starter that usually enables a short circuit to preheat the lamp filaments within 1.5 seconds, and then the opening of the short circuit to breakdown the gas. However, the lamp is not always lit, the glow starter will continue to re-ignite. Then, there is a permanent flicker of the fluorescent lamp that is particularly bothersome. Furthermore, the fluorescent lamp and the starter will be damaged. In order to overcome these drawbacks, electronic starters were proposed in the last ten years [6,7]. The major difference between the electronic circuit of the fluorescent lamp starter and that of other applications is that higher reliability and lower cost for mass manufactured. A typical electronic starter consists of a rectifier, a voltage detector, a preheating timer and a fire circuit as shown in Fig. 2 [8,10]. Figure 2. The block diagram of a typical electronic starter Figure 1. The standard topology of the fluorescent lamp, the magnetic ballast and the starter The electrical property of the fluorescent lamp is similar to that of an avalanche zener diode with a low and negative resistance in the gas after breakdown. First, the The rectifier is to rectify the input AC voltage to be as a similar DC voltage to ensure the preheating timer and the fire circuit to work well. The rectifier could be implement by using either the half-wave rectifier [6-9] or the full-wave rectifier [10,11]. The half-wave rectifier with the advantage of the lower cost always accompany with the magnetic noise [6-9]. The working sequence of the typical electronic starter /05/$ IEEE 423

2 is briefly described as the followings. First, the rectified voltage is measured and detected by the voltage detector. If a high voltage is detected, the preheating timer will be triggered and start to count a preheating time T ph. In the process of the preheating time T ph, the fire circuit work as a short circuit to make a current flow through the lamp filaments to achieve the preheating process. After the preheating time T ph, the preheating timer sends a trigging signal to fire circuit to work as an open circuit. At the fire circuit opening moment, the energy stored in the magnetic ballast is converted into a high surge voltage that causes the breakdown of the lamp gas. Finally, the fluorescent lamp is lit up, and the fire circuit is kept in open circuit state. As shown in Fig. 3(a), the preheating timer constructed by a RC circuit is to reduce the cost [6,7,8,10,11]. The preheating time T ph is determined by the product value of the resistor R T1 and the capacitor C T. This RC circuit timer has a limitation that cannot restart quickly since the discharged speed of the capacitor C T is limited by the product value of the resistor R T2 and the capacitor C T. To solve this problem, a RC timer with a resent control circuit has been shown in Fig. 3(b). fluorescent lamp will be reduced effectively. In an underhearting state, the fluorescent lamp is difficult to be lit. That means an adaptive preheating time is necessary in an advanced electronic starter. In addition, simple circuit with lower cost must be kept in the advanced electronic starter for mass manufactured. To achieve the above-mentioned high quality with low cost requirement, a Reset Control with Voltage Pull up Circuit (RCVPC) constructed by only a resistor and a diode is proposed in this paper. Besides, this proposed RCVPC can adapt the preheating time according to the input AC power and work well in a lower AC power situation. II. SYSTEM DESCRIPTION Fig. 4 shows the block diagram of the proposed Adaptive Electronic Starter (AES) that is constructed by a rectifier, a voltage detector, a RCVPC and a fire circuit. Figure 4. The block diagram of the proposed AES (a) (b) Figure 3. (a) a typical RC timer; (b) a typical RC timer with a reset control circuit The quick restart feature is performed by the switch S which can be closed to instantly discharge the capacitor C T. However, the control circuit in this reset control circuit is too complex to reduce the cost [9]. The preheating time of a typical electronic starter is fixed, that results a serious problem the lamp filaments over-hearting in a high AC power situation and under-hearting in a low AC power situation. In an over-hearting state, the using life of a The rectifier provides a dc voltage from the AC power. The voltage detector is designed to detect the voltage on the fluorescent lamp for evaluating the power level and monitoring the light on status. When the voltage detector detects the enough power, the circuit processes the preheating status for an adaptive preheating time to suitably preheat the lamp filaments. The adaptive preheating time is accurately controlled by the preheating timer and adapted by input AC power. The detail circuit functions will be illustrated in the next section. After the preheating time, the fire circuit can generate a pulse signal with high surge voltage to ignite the fluorescent lamp. The fluorescent lamp is; therefore, lit up. When the input AC power is turned off, the voltage detector detects this situation and triggers the RCVPC. Next the preheating timer returns to the initial state for a quick reset function. Finally, the fluorescent lamp can be quickly restarted again if necessary. III. CIRCUIT ANALYSIS Considering the circuit whose cost and size are limited for the better commercial benefit, the proposed circuit of the electronic starter, shown as Fig. 5, is designed to be as simple as possible. This electronic starter not only maintains all of features on the typical function, but also creates an adaptive preheating time and a lower AC power working ability. 424

detector consists of resistors R2 and R7, diode D6 and capacitor C2, the preheating timer circuit is constructed by capacitor C1 and resistances R3, R5, R6, the fire circuit

When the power turned on, the fluorescent lamp, which may be viewed as an open circuit, is not lit up. The AC power directly applies to the two terminals CN1 and CN2 of the AES.

At this period of time, the MOSFET Q1 will be turned on and pass the preheating current through the lamp filaments.

The MOSFET Q1 maintains in the turn on status until the transistor Q2 turns on. During this period of time, it is called preheating status. The equivalent circuit is shown as Fig.

3 Figure 5. The circuit of the proposed adaptive electronic starter Corresponding to the block diagram of the proposed AES, the full-wave rectifier includes diodes D1, D2, D3, D4, the voltage detector consists of resistors R2 and R7, diode D6 and capacitor C2, the preheating timer circuit is constructed by capacitor C1 and resistances R3, R5, R6, the fire circuit consists of MOSFET Q1, transistor Q2 and resistor R1, as well as the component diode D5 and resistor R4 plays the RCVPC. When the power turned on, the fluorescent lamp, which may be viewed as an open circuit, is not lit up. The AC power directly applies to the two terminals CN1 and CN2 of the AES. In addition, it is also rectified by the rectifier and filtered by the resistor R2 and capacitor C2. At this period of time, the MOSFET Q1 will be turned on and pass the preheating current through the lamp filaments. This is because the gate of MOSFET Q1 obtains high voltage which larger than the threshold voltage of MOSFET Q1. The MOSFET Q1 maintains in the turn on status until the transistor Q2 turns on. During this period of time, it is called preheating status. The equivalent circuit is shown as Fig. 6(a). In Fig. 6(a), voltage VQ1 and VR4 correspond to the voltage on the MOSFET internal resistance and the resistor R4 when the preheating current flows through it. Both voltage VQ1 and VR4 can be viewed as the DC voltage with ripple. For the bright analysis, the ripple can be neglected, the voltage on the capacitor C2 can be written as: V R 7 C 0.7 V 2 Q V 1 R (1) 4 R2 R7 (a) (b) Figure 6. The equivalent circuit of the electronic starter working at the preheating status After that, the equivalent circuit for the preheating status can be shown in Fig. 6(b). In Fig. 6(b), the preheating time T ph can be written as: 425

T ph VC 2 R5 R6 ) C loge VC V 2 ( 1 ON (2) T R R (3) 3 4 discharge 5 C1 R3 R4 where V ON is the voltage of capacitor C1 that can turn on the transistor Q2.

The gate voltage of MOSFET Q1, equivalent to the collector voltage of transistor Q1, will be pulled down to around 0.2 Volt. Furthermore, the MOSFET Q1 will be turned off immediately.

(2), it is clear that the preheating time T ph can be changed by the voltage V C2, and the voltage V C2 is mainly controlled by voltage V R4 +V Q1.

4 T ph VC 2 R5 R6 ) C loge VC V 2 ( 1 ON (2) T R R (3) 3 4 discharge 5 C1 R3 R4 where V ON is the voltage of capacitor C1 that can turn on the transistor Q2. When the preheating status is complete, the base voltage of Q2 will rise to 0.7 Volt. The transistor Q2 will turn on. The gate voltage of MOSFET Q1, equivalent to the collector voltage of transistor Q1, will be pulled down to around 0.2 Volt. Furthermore, the MOSFET Q1 will be turned off immediately. At this time, the preheating current will be stopped. Finally, the magnetic ballast will release the very high voltage on the fluorescent lamp filaments for lighting on the lamp. From Equ. (2), it is clear that the preheating time T ph can be changed by the voltage V C2, and the voltage V C2 is mainly controlled by voltage V R4 +V Q1. Since the voltage V R4 +V Q1 is proportioned to the input AC power, the preheating time can be really enlarged in a lower input AC power situation to obtain a sufficient preheating effect. On the other hand, the preheating time is reduced in a higher input AC power situation to avoid overheating the lamp filament. Since the preheating time is a positive real vale, the voltage V C2 must be bigger than the voltage V ON. The V C2 voltage in the proposed circuit is added V R4 Volt. comparing with a typical electronic starter. That means the proposed RCVPC can effectively help an electronic starter work well in a lower AC power situation. After the preheating process, the fluorescent lamp enters the lighting up status. Its equivalent circuit is shown in Fig. 7. Both of the voltages on the capacitor C1 and C2 are kept on fully charged. Since R 4 <<R 3, then we have that T disch arg e 5 R4 C1 (4) Since resistor R4 is quit small (i.e., 2), the discharging time would be much shorter. Therefore, the proposed RCVPC can effectively speed up the reset speed of the electronic starter. Therefore a very fast restart performance can be achieved. Figure 8. The equivalent circuit at the power off status IV. EXPERIMENTAL RESULTS AND DISCUSSION The experimental results of the commercial electronic starter are shown in Fig. 9. In the Fig. 9, we can find that the preheating time is about 0.9 second. Furthermore, the fluorescent lamp voltage takes about 0.7 second to enter the steady state status. However, the commercial electronic starter cannot provide a single-pulse ignition. Moreover the more extra pulse ignition will deteriorate the Fluorescent lamp [8]. Figure 7. The equivalent circuit of the electronic starter in the light on status After the AC power is turned off, the lamp is off, as well. The voltage on C1 should be discharged quickly for the next restart. In the proposed RCVPC, a new discharge path is created to achieve the instant discharge from the capacitor C1 through the diode D5 and the resistor R4. Fig. 8 shows the equivalent circuit at the AC power off status. The voltage on capacitor C1 is discharged rapidly through the resistor R3 and R4. The discharging time constant T discharge is written as: Figure 9. The voltage on the lamp for the commercial electronic starter (500V/div, 400msec/div) The result of the AES proposed in this paper is shown in Fig. 10. Clearly, we obtain the signal-pulse ignition. The 426

5 preheating time is about 0.7 second, and the lamp can be immediately lit on after the signal-pulse ignition. Figure 10. The voltage on the lamp under the signal-pulse ignition on the positive ignition for the new proposed electronic starter (500V/div, 400msec/div) The instant restart of the proposed AES is achieved under 95V and shown in Fig. 11. The experimental results show that the proposed electronic can quickly reignite the fluorescent lamp with a single-pulse ignition as the theoretical prediction. Figure 12. The curve of the preheating time versus the input AC voltage V. CONCLUSION In this paper, a cost competitive circuit of an adaptive electronic starter for fluorescent lamps is proposed to provide a single-pulse ignition and fast reset feature. Only a resistor and a diode are used to implement the fast restart function and the instant re-ignition. This paper presents a new circuit topology for calculating the related parameters to obtain the above features. Finally, a prototype for 20W fluorescent lamps is designed and implemented successfully. The experimental evaluation of both single-pulse ignition and quick restart performance has been completed. A cost competitive circuit of an electronic starter with the powerful function is beneficial for the commercial purpose. ACKNOWLEDGMENT This work was sponsored by the National Science Council, Taiwan, R. O. C., Project number: NSC E CC3. Figure 11. The voltage on the lamp under the quick re-ignition for the new proposed electronic starter on the abnormal working voltage 95V (500V/div, 1sec/div) Finally, The curve of the preheating time versus the input AC voltage is shown in Fig. 12. It is clear that the preheating time of the proposed AES can adapt its preheating time according to the theoretical analysis of the input AC power. REFERENCES [1] S. T. S. Lee, H. S. H. Chung, and S.Y Hui, A novel electrode power profiler for dimmable ballasts using DC link voltage and switching frequency controls, IEEE Trans. Power Electronics, vol. 19, iss. 3, pp , May [2] T. F. Wu, Y. C. Wu, and Z. Y. Su, Design considerations for single-stage electronic ballast with dimming feature, IEEE Trans. Industrial Applications, vol. 37, iss. 5, pp , Setp [3] G. C. Hsieh and C. H. Lin, Harmonized strategy for breaking the striations in the fluorescent lamp, IEEE Trans. Industrial Electronics, vol. 48, iss. 2, pp , April [4] H. L. Cheng, C. S. Moo, and W. M. Chen, A novel single-stage high-power-factor electronic ballast with symmetrical topology, IEEE Trans. Industrial Electronics, vol. 50, iss. 4, pp , Aug

6 [5] C. S. Lin and C. L. Chen, A novel single-stage push-pull electronic ballast with high input power factor, IEEE Trans. Industrial Electronics, vol. 48, iss. 4, pp , Aug [6] K. I. Gyoten and N. Yoshikawa, Development of an electronic starter for fluorescent lamps, Journal of IES. pp , [7] S. Yeo, D. H. Lee, and S. B. Song, A simple electronic starter capable of end-of-life protection for fluorescent lamps, Proc. IEEE Applied Power Electronics Conference and Exposition (APEC), vol. 1, pp , March [8] Chen-Kuo Ku The Improved fast starter of the electronic fluorescent lamp Republic of China Patten: /06/01 [9] C. C. Lu The electronic starter of the fluorescent lamp Republic of China Patten: /11/11 [10] Chen-Kuo Ku Electronic starter for fluorescent lamps U.S.A. PattenUS /08/05 [11] B. Marco, Electronic starter circuit for fluorescent lamp, U.S.A. PattenUS , 1997/04/01 428

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