The Current Injection Method for AC Plasma Display ... - IEEE Xplore
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 51, NO. 3, JUNE 2004
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The Current Injection Method for AC Plasma Display Panel (PDP) Sustainer Jun-Young Lee, Jin-Sung Kim, Nam-Sung Jung, and Bo-Hyung Cho, Senior Member, IEEE
Abstract—A new concept of energy recovery for a plasma display panel (PDP) is proposed. Different from conventional LC resonant sustaining drivers, the current built up before inverting the polarity of the panel electrodes is utilized to change the panel polarity together with energy previously charged in panel capacitance. This operation provides zero-voltage switching of switches and reduction of electromagnetic interference by rejecting the surge current when the sustain switches are turned on. The buildup current helps to reduce the transition time of the panel polarity and may produce more stable light waveforms. This method is suitable for a PDP sustaining driver requiring stable light emission characteristic while it maintains low circuit loss like the series-resonant-type energy recovery circuit which is known to be a very effective method. Index Terms—Energy recovery, plasma display panel (PDP), resonance.
Fig. 1. Simplified PDP structure with three electrodes.
I. INTRODUCTION
T
HE plasma display panel (PDP) has an advantages over other flat panel displays including wide view angle, large screen, high brightness, and thinness. Thanks to the attractive merits, the PDP is expected to be a promising candidate in the display market [1]. Fig. 1 shows the simplified PDP structure with three electrodes. It consists of two glass plates with chemically stable rare gases filled between them. The scanning and sustaining electrodes are built on the front glass, which is coated with a dielectric layer and the addressing electrode is on the rear glass. A desired color light can be obtained by exciting the phosphors on the addressing electrode to emit visible light with the ultraviolet photons generated by gas discharge [2]. The operation of a PDP is divided into three periods of setup, addressing, and sustaining periods. During the setup period, all of the PDP cells are erased and prepared to carry out addressing by forming adequate wall charges. After that, selective write discharges to form an image are ignited by applying data and scanning pulses to the addressing and scanning electrodes, respectively [3]. Since addressing discharge itself emits an insufficient visible light, high-voltage ac square pulses are continuously applied between sustaining and scanning electrodes for strong light emission of selective cells. The high-voltage pulses can be generated using a simple full-bridge driver, as
Manuscript received April 16, 2002; revised July 18, 2003. Abstract published on the Internet January 14, 2004. J.-Y. Lee, J.-S. Kim, and N.-S. Jung are with the PDP Circuit Development 1 Team, PDP Division, Samsung SDI Company Ltd., Chonan City 330-300, Korea (e-mail: [email protected]; [email protected]). B.-H. Cho is with the Power Electronics Laboratory, School of Electrical Engineering, Seoul National University, Seoul 151-742, Korea (e-mail: bhcho@ snu.ac.kr). Digital Object Identifier 10.1109/TIE.2004.825359
Fig. 2.
Basic full-bridge sustaining driver and its sustain waveform.
shown in Fig. 2, and most of the PDP power is consumed during this sustaining period. Since a dielectric layer is encrusted on sustaining and scanning electrodes, capacitance between two electrodes exits inherently. When a sustaining pulse is applied is dissipated in to electrodes, an amount of energy switches and parasitic resistances of wire during charging and is panel capacitance and is discharging transients, where sustain voltage. If an average frequency of sustaining pulse is , [4]. Without proper then the total dissipated power is methods to recover the energy, a large amount of surge current causes electromagnetic interference (EMI) and the heating problem of switching devices. To solve the problems, Webber et al. suggest an energy recovery circuit (ERC) using the series LC resonant concept [5]. It features high efficiency and good circuit flexibility to cope with various driving methods, which leads many PDP makers such as Samsung, LG, Matsushita, and FHP to adopt this circuit. Ohba et al. have reduced this circuit supporting parallel LC resonance, adopted by NEC [4]. Several researchers have studied various circuit types to improve
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Fig. 3. LC resonant-type PDP driving circuit. (a) Series resonant type. (b) Parallel resonant type.
Fig. 4.
Equivalent circuits during LC resonance and the panel voltage waveforms. (a) Series resonant type. (b) Parallel resonant type.
performance and reduce circuit volumes [4], [7]. However, due to the considerable circulating current, efficiency and flexibility are not good compared with conventional PDP drivers, which makes it difficult to produce them on a commercial scale. In this paper, new concept of energy recovery using current injection method (CIM) is proposed. Before inverting the polarity of the panel electrodes, the inductor current is built up and it is used to invert the panel polarity together with energy previously charged in panel capacitance. This operation helps to achieve the zero-voltage switching of switches and reduce the EMI by rejecting the surge current. In addition, it helps to reduce the transition time of the panel polarity, which may produce more stable light waveforms. By reducing the circulating current, good circuit efficiency can be obtained in the prototype driver for a 42-in PDP.
II. PRIOR APPROACHES Fig. 3 shows the prior approaches suggested by Webber and Ohba using series or parallel LC resonance. Their equivalent circuits during the LC resonant period and the panel voltage waveforms are shown in Fig. 4. The sustain voltages go up or ramp down to some voltage level in a resonant manner and sustain switches are turned on to hold a sustain voltage. At that moment, a large surge current occurs. In this figure, means the parasitic resistance including on-resistances of means the diode forward drop. Based on switches and this figure, the panel voltage can be obtained as follows: series resonant type
(1)
LEE et al.: CURRENT INJECTION METHOD FOR AC PLASMA PANEL DISPLAY (PDP) SUSTAINER
Fig. 5.
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PDP driver circuit to adopt the new method.
parallel resonant type
III. MODE ANALYSIS (2)
where
and . If and can be ignored, (1) and (2) are simply rewritten as series resonant type (3) parallel resonant type
Fig. 5 is the PDP driver circuit to adopt the CIM. This circuit is similar to a series resonant type circuit except that the energy storage capacitors are connected in series between and ground. However, the operation is different from the simple LC resonant method. Fig. 6 shows the key waveforms of the proposed method, divided by eight modes, and their operational mode diagrams are as shown in Fig. 7. It is assumed that beand are on and fore the start of mode 1, the switches . In addition, recovery capacitors of , , , are charged to half of the sustain voltage. Because the and operation of the two half cycles is symmetric, mode analysis is performed about the first half cycle. A. Mode 1
(4) . The peak values of the two equations where occur at and can be obtained as follows: series resonant type
Referring to Fig. 7, once the switch of the Y electrode is turned on, there forms a current path including , , , and in sequence. On the other hand, when the switch of the X elec, , trode is turned on, there forms a current path including , and in sequence. Accordingly, and flowing to and linearly increase with the slope of to store the magnetic energy in the inductors. The currents are expressed as
(5) parallel resonant type
(7) B. Mode 2
(6) It says that increase of the parasitic resistance causes the recovery efficiency to be degraded. Naturally, it is necessary to reduce the parasitic resistance by designing the circuit board optimally as well as choosing switching devices with small on-resistance and low on-drop voltage to minimize the hard-switching stress and improve the recovery performance. However, since it is impossible to get rid of the parasitic components completely, EMI and switching stress caused by the surge current are inevitable. It shows the limitations of the simple LC resonant method. On the other hand, reduction of the inductor value produces similar results and, thus, using a too small value of is not desirable in the aspects of driving loss and EMI.
When and are turned off, the currents built up during , and in sequence. mode 1 flow through , , , , A resonant current caused by the panel capacitance flows and of the panel capacitor is inverted in the terminal voltage to . That is, the Y electrode voltage polarity from at the Y electrode rises from ground to the sustain voltage and the X electrode voltage at the X electrode falls from the sustain voltage to ground. In this mode, the equivalent circuit , , and are written as is Fig. 8. From this circuit
(8) (9) where
and
.
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Fig. 6. Key waveforms of the proposed method.
C. Mode 3
IV. DESIGN CONSIDERATIONS
After inverting the polarity of the panel capacitance, the body are turned on. Accordingly, the current diodes of and starts to flow through , , , , and the body diode of . flows through , , , , and the body diode Similarly, are turned on to hold the panel of . Afterwards, when and electrode voltage as the sustain voltage and ground, zero-voltage switching is accomplished, which removes the switching loss and and are ramped down surge current. During this mode, . This can be expressed as to zero with the slope of
A. Relationship of Transition Time Buildup Time
, Inductor , and
The transition time is defined as the time during which the panel electrode voltage is changed between the sustain is the time during voltage and ground. The buildup time which the inductor current is built up prior to the inversion of the panel polarity. It is depicted in Fig. 9. By replacing with , (9) becomes (11)
(10) D. Mode 4
From this equation, the transition time can be found as
After and are completely reset, and are turned off. Switching losses do not occur since switch currents do not and are maintained at the sustain remain. During mode 4, voltage and ground. E. Mode 5–8 The remaining half cycle operation is similar to the previous analysis. It is noted that, during mode 2, the recovery capacitor delivers sufficient energy to the inductor so that regardless of the circuit loss, the voltages at sustaining (Y) and scanning (X) electrodes can go up to the sustain voltage or ramp down to the ground level completely with the aid of this delivered energy. Moreover, the remaining energy of inductors can be used for zero-voltage switching of switches after inverting the panel polarity.
(12) . The transition time becomes where reduced as the buildup time becomes increased with a fixed value of . It provides another design factor besides the inductor value. B. Power Losses Until now, many PDP driving circuits have been developed, but they suffer from low efficiency compared with series and parallel resonant types. Circuit efficiency is an important factor to determine whether the newly developed method is usable or not. This section shows power loss equations of the proposed
LEE et al.: CURRENT INJECTION METHOD FOR AC PLASMA PANEL DISPLAY (PDP) SUSTAINER
Fig. 7.
Operational mode diagrams.
Fig. 8.
Equivalent circuit for the proposed method during mode 2.
method to predict the circuit consumption and investigate the trend of power consumption according to circuit parameters. Furthermore, they are used for suggesting a design guideline. Based on the mode analysis and Fig. 9, the power dissipated in diodes and switches averaged over a switching period can be written as follows:
(13)
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Fig. 9. Current waveforms of energy recovery and sustain circuits.
(14)
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Fig. 10.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 51, NO. 3, JUNE 2004
Calculated power losses under T and L variations at V = 165 V when panel discharge is removed.
(15) where and are on-resistances of energy recovery and sustain MOSFETs, respectively. In addition, since , , , and cannot the clamping currents through be ignored, the power loss caused by this current expressed as (16) should be considered
(16)
Fig. 11.
42-in test PDP set for the proposed method.
where is the output capacitance of the energy recovery switches and
TABLE I KEY COMPONENTS FOR PROTOTYPE DRIVER
(17) Since the power dissipation caused by a large amount of surge current of sustain switches can be removed by using this method, most of the circuit losses are conduction loss. Different from simple LC resonant methods, it has some circulating current due to the current built up before inverting the panel polarity and this current may contribute to degrade the circuit efficiency. Using (13)–(17), the power losses under the buildup time and inductor value variations can be calculated with parameters used in prototype PDP driver, which is
shown in Fig. 10. The power loss goes up as the buildup times and inductor values are varied so that the circulating current
LEE et al.: CURRENT INJECTION METHOD FOR AC PLASMA PANEL DISPLAY (PDP) SUSTAINER
Fig. 12.
Currents drawn from the sustain power supply at V = 165 V with buildup time and resonant inductor variations.
Fig. 13.
Sustain voltage and inductor current waveforms at L = 0:42 H, T = 150 ns, and V = 165 V. (a) Y electrode. (b) X electrode.
increases. Therefore, it is not desirable to choose an excessively large buildup time or small inductor value. V. DESIGN To validate the proposed method, a prototype PDP driver circuit has been designed for 42-in PDP panels with the following specifications: • sustain voltage: V; kHz; • switching frequency: ns; • transition time: about nF; • panel capacitance:
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lines, • scan method: single scan (scan line lines). address line The test set is as shown in Fig. 11. The PDP driver is divided into two board of X and Y boards to reduce the parasitic impedance between board outputs and panel electrodes. Scan boards are located at between Y board and Y electrode. The logic board to generate switching signals and perform various algorithms is at the right side of Y board. Supplying power is carried out by switched-mode power supply (SMPS) at the left side of X board. Table I shows the circuit components of sustain and energy recovery circuits. Fig. 12 is the interaction plot that shows
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Fig. 14.
Sustain voltage and light waveforms with panel discharge at V = 165 V. (a) CIM. (b) Series resonant method.
Fig. 15.
Power consumption of PDP set with and without panel discharge at V = 165 V.
the currents supplied by the sustain power supply with buildup and resonant inductor variations when the panel distime charge is removed to observe the circuit loss itself. The power loss is measured under five test image patterns such as full white, full red, full green, full blue, and nine white square images. The full white image pattern has the largest discharge current of about 150 A in the 42-in panel, but its sustain pulse number is smallest among other patterns. It is about 400 pulses. Meanwhile, the nine white square pattern has the smallest discharge current, but about 2000 pulses are applied to the panel to obtain a peak brightness. The interaction plot shows that when and are selected as 0.42 H and 150 ns, the circuit power loss can be minimized. Using the selected values, the transition time can be obtained as 500 ns from (12).
VI. EXPERIMENTAL RESULTS Fig. 13 shows the sustain voltage and inductor current waveforms. Before the panel polarity is inverted, the inductor currents are built up to about 35 A and they are recovered to the capacitors after changing the panel polarity. The clamping currents caused by parasitic capacitance of energy recovery switches are also shown in this figure. The measured waveforms in box shows that soft switching can be accomplished. Fig. 14 is the voltage waveforms of the panel electrodes accompanied by light waveforms when panel discharge for emitting light happens. As can be seen in this figure, the start voltage of the panel discharge is higher than series resonant type and more stable light waveform can be obtained especially at the nine white square image pattern. Fig. 15 is the power loss comparison plot. It shows that
LEE et al.: CURRENT INJECTION METHOD FOR AC PLASMA PANEL DISPLAY (PDP) SUSTAINER
Fig. 16.
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EMI radiation comparisons between two methods. (a) CIM. (b) Series resonant method.
the power loss is similar to that of series resonant type energy recovery circuit. It is desirable characteristic since this type has been known to be very effective method. The test result of EMI radiation at full white image pattern is as shown in Fig. 16. The newly developed method shows a lower EMI level at the 100 MHz–200-MHz band due to the reduction of surge current when the sustain switches conduct. VII. CONCLUSION In this paper, a new concept of energy recovery using current injection method (CIM) was proposed and verified with a 42 in PDP panel. Experimental results show that with the help of the buildup inductor current just prior to inverting the panel polarity, zero-voltage switching of switches can be achieved regardless of the parasitic resistance and it reduces the EMI caused by the surge current. The prototype driver circuit improves the light waveform uniformity and sustain voltage waveform while it has a desirable characteristic that power loss does not fall behind that of the series resonant method. Therefore, the proposed sustainer is expected to be suitable for a PDP sustaining driver requiring stable discharge characteristics. This concept can be applied to a parallel resonant driver and address recovery circuit as well as a series resonant driver. REFERENCES [1] A. Sobel, “Plasma displays,” IEEE Trans. Plasma Sci., vol. 19, pp. 1032–1047, Dec. 1991.
[2] H. Hirakawa, T. Katayama, S. Juroki, H. Nakahara, T. Nanto, K. Yoshikawa, A. Otsuka, and M. Wakitani, “Cell structure and driving method of a 25-in (64 cm) diagonal high-resolution color ac plasma display,” in Proc. Symp. Society for Information Display, vol. 29, 1998, pp. 279–282. [3] L. F. Webber, “Plasma display device challenges,” in Proc. Asia Display’98, 1998, pp. 15–27. [4] S. Y. Lin, C. L. Chen, and K. Lee, “Novel regenerative sustain driver for plasma display panel,” in Proc. IEEE PESC’98, Fukuoka, Japan, 1998, pp. 1739–1743. [5] L. F. Webber and K. W. Warren, “Power efficient sustain drivers and address drivers for plasma panel,” U.S. Patent 4 866 349, Sept. 1989. [6] M. Ohba and Y. Sano, “Energy recovery driver for a dot matrix AC plasma panel with a parallel resonant circuit allowing power reduction,” U.S. Patent 5 670 974, Sept. 1997. [7] H. B. Hsu, C. L. Chen, S. Y. Lin, and K. M. Lee, “Representative power electronics driver for plasma panel in sustain mode operation,” IEEE Trans. Ind. Electron., vol. 47, pp. 1118–1125, Oct. 2000.
Jun-Young Lee was born in Seoul, Korea, in 1970. He received the B.S. degree from Korea University, Seoul, Korea, in 1993, and the M.S. and Ph.D. degrees from Korea Advanced Institute of Science and Technology (KAIST), Taejon, Korea, in 1996 and 2001, respectively, all in electrical engineering. He is currently a Manager with the PDP Division, Samsung SDI Company Ltd., Chonan City, Korea. His research interests are in the area of power electronics, including ac/dc PFC converter topology design, converter modeling, soft-switching techniques, display driving circuits, PDP driving systems, and address energy recovery technology. Dr. Lee is a Member of the Korea Institute of Electrical Engineering (KIEE) and Korea Institute of Power Electronics (KIPE).
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Jin-Sung Kim was born in Seoul, Korea, in 1972. He received the B.S. and M.S. degrees from Seoul National University, Seoul, Korea, in 1996 and 1998, respectively. He is currently a Manager with the PDP Division, Samsung SDI Company Ltd., Chonan City, Korea, in charge of driver circuit development for PDPs. His research interests include display driving circuits, PDP driving methods, and address energy recovery circuits.
Nam-Sung Jung was born in Seoul, Korea, in 1962. He received the B.S. degree from Hanyang University, Seoul, Korea, in 1985, and the M.S. and Ph.D. degrees from Korea Advanced Institute of Science and Technology (KAIST), Taejon, Korea, in 1990 and 1999, respectively, all in electrical engineering. He is currently a General Manager with the PDP Division, Samsung SDI Company Ltd., Chonan City, Korea. His research interests are in the area of power electronics, including inverter and converter topology design, modeling, and soft-switching techniques in PDPs. Dr. Jung is a Member of the Korean Information Display Society (KIDS) and Korea Institute of Power Electronics (KIPE).
Bo-Hyung Cho (M’89–SM’95) received the B.S. and M.E. degrees from the California Institute of Technology, Pasadena, and the Ph.D. degree from Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, all in electrical engineering. Prior to his research at Virginia Tech, he worked for two years as a Member of Technical Staff, Power Conversion Electronics Department, TRW Defense and Space System Group, where he was involved in the design and analysis of spacecraft power processing equipment. From 1982 to 1995, he was a Professor in the Department of Electrical Engineering, Virginia Tech. In 1995, he joined the School of Electrical Engineering, Seoul National University, Seoul, Korea, where he is currently a Professor. His main research interests include power electronics, modeling, analysis, and control of spacecraft power processing equipment, power systems for space stations and space platforms, and distributed power systems. Dr. Cho received the 1989 Presidential Young Investigator Award from the National Science Foundation. He is a member of Tau Beta Pi.
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The Current Injection Method for AC Plasma Display Panel (PDP) Sustainer Jun-Young Lee, Jin-Sung Kim, Nam-Sung Jung, and Bo-Hyung Cho, Senior Member, IEEE
Abstract—A new concept of energy recovery for a plasma display panel (PDP) is proposed. Different from conventional LC resonant sustaining drivers, the current built up before inverting the polarity of the panel electrodes is utilized to change the panel polarity together with energy previously charged in panel capacitance. This operation provides zero-voltage switching of switches and reduction of electromagnetic interference by rejecting the surge current when the sustain switches are turned on. The buildup current helps to reduce the transition time of the panel polarity and may produce more stable light waveforms. This method is suitable for a PDP sustaining driver requiring stable light emission characteristic while it maintains low circuit loss like the series-resonant-type energy recovery circuit which is known to be a very effective method. Index Terms—Energy recovery, plasma display panel (PDP), resonance.
Fig. 1. Simplified PDP structure with three electrodes.
I. INTRODUCTION
T
HE plasma display panel (PDP) has an advantages over other flat panel displays including wide view angle, large screen, high brightness, and thinness. Thanks to the attractive merits, the PDP is expected to be a promising candidate in the display market [1]. Fig. 1 shows the simplified PDP structure with three electrodes. It consists of two glass plates with chemically stable rare gases filled between them. The scanning and sustaining electrodes are built on the front glass, which is coated with a dielectric layer and the addressing electrode is on the rear glass. A desired color light can be obtained by exciting the phosphors on the addressing electrode to emit visible light with the ultraviolet photons generated by gas discharge [2]. The operation of a PDP is divided into three periods of setup, addressing, and sustaining periods. During the setup period, all of the PDP cells are erased and prepared to carry out addressing by forming adequate wall charges. After that, selective write discharges to form an image are ignited by applying data and scanning pulses to the addressing and scanning electrodes, respectively [3]. Since addressing discharge itself emits an insufficient visible light, high-voltage ac square pulses are continuously applied between sustaining and scanning electrodes for strong light emission of selective cells. The high-voltage pulses can be generated using a simple full-bridge driver, as
Manuscript received April 16, 2002; revised July 18, 2003. Abstract published on the Internet January 14, 2004. J.-Y. Lee, J.-S. Kim, and N.-S. Jung are with the PDP Circuit Development 1 Team, PDP Division, Samsung SDI Company Ltd., Chonan City 330-300, Korea (e-mail: [email protected]; [email protected]). B.-H. Cho is with the Power Electronics Laboratory, School of Electrical Engineering, Seoul National University, Seoul 151-742, Korea (e-mail: bhcho@ snu.ac.kr). Digital Object Identifier 10.1109/TIE.2004.825359
Fig. 2.
Basic full-bridge sustaining driver and its sustain waveform.
shown in Fig. 2, and most of the PDP power is consumed during this sustaining period. Since a dielectric layer is encrusted on sustaining and scanning electrodes, capacitance between two electrodes exits inherently. When a sustaining pulse is applied is dissipated in to electrodes, an amount of energy switches and parasitic resistances of wire during charging and is panel capacitance and is discharging transients, where sustain voltage. If an average frequency of sustaining pulse is , [4]. Without proper then the total dissipated power is methods to recover the energy, a large amount of surge current causes electromagnetic interference (EMI) and the heating problem of switching devices. To solve the problems, Webber et al. suggest an energy recovery circuit (ERC) using the series LC resonant concept [5]. It features high efficiency and good circuit flexibility to cope with various driving methods, which leads many PDP makers such as Samsung, LG, Matsushita, and FHP to adopt this circuit. Ohba et al. have reduced this circuit supporting parallel LC resonance, adopted by NEC [4]. Several researchers have studied various circuit types to improve
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Fig. 3. LC resonant-type PDP driving circuit. (a) Series resonant type. (b) Parallel resonant type.
Fig. 4.
Equivalent circuits during LC resonance and the panel voltage waveforms. (a) Series resonant type. (b) Parallel resonant type.
performance and reduce circuit volumes [4], [7]. However, due to the considerable circulating current, efficiency and flexibility are not good compared with conventional PDP drivers, which makes it difficult to produce them on a commercial scale. In this paper, new concept of energy recovery using current injection method (CIM) is proposed. Before inverting the polarity of the panel electrodes, the inductor current is built up and it is used to invert the panel polarity together with energy previously charged in panel capacitance. This operation helps to achieve the zero-voltage switching of switches and reduce the EMI by rejecting the surge current. In addition, it helps to reduce the transition time of the panel polarity, which may produce more stable light waveforms. By reducing the circulating current, good circuit efficiency can be obtained in the prototype driver for a 42-in PDP.
II. PRIOR APPROACHES Fig. 3 shows the prior approaches suggested by Webber and Ohba using series or parallel LC resonance. Their equivalent circuits during the LC resonant period and the panel voltage waveforms are shown in Fig. 4. The sustain voltages go up or ramp down to some voltage level in a resonant manner and sustain switches are turned on to hold a sustain voltage. At that moment, a large surge current occurs. In this figure, means the parasitic resistance including on-resistances of means the diode forward drop. Based on switches and this figure, the panel voltage can be obtained as follows: series resonant type
(1)
LEE et al.: CURRENT INJECTION METHOD FOR AC PLASMA PANEL DISPLAY (PDP) SUSTAINER
Fig. 5.
617
PDP driver circuit to adopt the new method.
parallel resonant type
III. MODE ANALYSIS (2)
where
and . If and can be ignored, (1) and (2) are simply rewritten as series resonant type (3) parallel resonant type
Fig. 5 is the PDP driver circuit to adopt the CIM. This circuit is similar to a series resonant type circuit except that the energy storage capacitors are connected in series between and ground. However, the operation is different from the simple LC resonant method. Fig. 6 shows the key waveforms of the proposed method, divided by eight modes, and their operational mode diagrams are as shown in Fig. 7. It is assumed that beand are on and fore the start of mode 1, the switches . In addition, recovery capacitors of , , , are charged to half of the sustain voltage. Because the and operation of the two half cycles is symmetric, mode analysis is performed about the first half cycle. A. Mode 1
(4) . The peak values of the two equations where occur at and can be obtained as follows: series resonant type
Referring to Fig. 7, once the switch of the Y electrode is turned on, there forms a current path including , , , and in sequence. On the other hand, when the switch of the X elec, , trode is turned on, there forms a current path including , and in sequence. Accordingly, and flowing to and linearly increase with the slope of to store the magnetic energy in the inductors. The currents are expressed as
(5) parallel resonant type
(7) B. Mode 2
(6) It says that increase of the parasitic resistance causes the recovery efficiency to be degraded. Naturally, it is necessary to reduce the parasitic resistance by designing the circuit board optimally as well as choosing switching devices with small on-resistance and low on-drop voltage to minimize the hard-switching stress and improve the recovery performance. However, since it is impossible to get rid of the parasitic components completely, EMI and switching stress caused by the surge current are inevitable. It shows the limitations of the simple LC resonant method. On the other hand, reduction of the inductor value produces similar results and, thus, using a too small value of is not desirable in the aspects of driving loss and EMI.
When and are turned off, the currents built up during , and in sequence. mode 1 flow through , , , , A resonant current caused by the panel capacitance flows and of the panel capacitor is inverted in the terminal voltage to . That is, the Y electrode voltage polarity from at the Y electrode rises from ground to the sustain voltage and the X electrode voltage at the X electrode falls from the sustain voltage to ground. In this mode, the equivalent circuit , , and are written as is Fig. 8. From this circuit
(8) (9) where
and
.
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Fig. 6. Key waveforms of the proposed method.
C. Mode 3
IV. DESIGN CONSIDERATIONS
After inverting the polarity of the panel capacitance, the body are turned on. Accordingly, the current diodes of and starts to flow through , , , , and the body diode of . flows through , , , , and the body diode Similarly, are turned on to hold the panel of . Afterwards, when and electrode voltage as the sustain voltage and ground, zero-voltage switching is accomplished, which removes the switching loss and and are ramped down surge current. During this mode, . This can be expressed as to zero with the slope of
A. Relationship of Transition Time Buildup Time
, Inductor , and
The transition time is defined as the time during which the panel electrode voltage is changed between the sustain is the time during voltage and ground. The buildup time which the inductor current is built up prior to the inversion of the panel polarity. It is depicted in Fig. 9. By replacing with , (9) becomes (11)
(10) D. Mode 4
From this equation, the transition time can be found as
After and are completely reset, and are turned off. Switching losses do not occur since switch currents do not and are maintained at the sustain remain. During mode 4, voltage and ground. E. Mode 5–8 The remaining half cycle operation is similar to the previous analysis. It is noted that, during mode 2, the recovery capacitor delivers sufficient energy to the inductor so that regardless of the circuit loss, the voltages at sustaining (Y) and scanning (X) electrodes can go up to the sustain voltage or ramp down to the ground level completely with the aid of this delivered energy. Moreover, the remaining energy of inductors can be used for zero-voltage switching of switches after inverting the panel polarity.
(12) . The transition time becomes where reduced as the buildup time becomes increased with a fixed value of . It provides another design factor besides the inductor value. B. Power Losses Until now, many PDP driving circuits have been developed, but they suffer from low efficiency compared with series and parallel resonant types. Circuit efficiency is an important factor to determine whether the newly developed method is usable or not. This section shows power loss equations of the proposed
LEE et al.: CURRENT INJECTION METHOD FOR AC PLASMA PANEL DISPLAY (PDP) SUSTAINER
Fig. 7.
Operational mode diagrams.
Fig. 8.
Equivalent circuit for the proposed method during mode 2.
method to predict the circuit consumption and investigate the trend of power consumption according to circuit parameters. Furthermore, they are used for suggesting a design guideline. Based on the mode analysis and Fig. 9, the power dissipated in diodes and switches averaged over a switching period can be written as follows:
(13)
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Fig. 9. Current waveforms of energy recovery and sustain circuits.
(14)
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Fig. 10.
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Calculated power losses under T and L variations at V = 165 V when panel discharge is removed.
(15) where and are on-resistances of energy recovery and sustain MOSFETs, respectively. In addition, since , , , and cannot the clamping currents through be ignored, the power loss caused by this current expressed as (16) should be considered
(16)
Fig. 11.
42-in test PDP set for the proposed method.
where is the output capacitance of the energy recovery switches and
TABLE I KEY COMPONENTS FOR PROTOTYPE DRIVER
(17) Since the power dissipation caused by a large amount of surge current of sustain switches can be removed by using this method, most of the circuit losses are conduction loss. Different from simple LC resonant methods, it has some circulating current due to the current built up before inverting the panel polarity and this current may contribute to degrade the circuit efficiency. Using (13)–(17), the power losses under the buildup time and inductor value variations can be calculated with parameters used in prototype PDP driver, which is
shown in Fig. 10. The power loss goes up as the buildup times and inductor values are varied so that the circulating current
LEE et al.: CURRENT INJECTION METHOD FOR AC PLASMA PANEL DISPLAY (PDP) SUSTAINER
Fig. 12.
Currents drawn from the sustain power supply at V = 165 V with buildup time and resonant inductor variations.
Fig. 13.
Sustain voltage and inductor current waveforms at L = 0:42 H, T = 150 ns, and V = 165 V. (a) Y electrode. (b) X electrode.
increases. Therefore, it is not desirable to choose an excessively large buildup time or small inductor value. V. DESIGN To validate the proposed method, a prototype PDP driver circuit has been designed for 42-in PDP panels with the following specifications: • sustain voltage: V; kHz; • switching frequency: ns; • transition time: about nF; • panel capacitance:
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lines, • scan method: single scan (scan line lines). address line The test set is as shown in Fig. 11. The PDP driver is divided into two board of X and Y boards to reduce the parasitic impedance between board outputs and panel electrodes. Scan boards are located at between Y board and Y electrode. The logic board to generate switching signals and perform various algorithms is at the right side of Y board. Supplying power is carried out by switched-mode power supply (SMPS) at the left side of X board. Table I shows the circuit components of sustain and energy recovery circuits. Fig. 12 is the interaction plot that shows
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Fig. 14.
Sustain voltage and light waveforms with panel discharge at V = 165 V. (a) CIM. (b) Series resonant method.
Fig. 15.
Power consumption of PDP set with and without panel discharge at V = 165 V.
the currents supplied by the sustain power supply with buildup and resonant inductor variations when the panel distime charge is removed to observe the circuit loss itself. The power loss is measured under five test image patterns such as full white, full red, full green, full blue, and nine white square images. The full white image pattern has the largest discharge current of about 150 A in the 42-in panel, but its sustain pulse number is smallest among other patterns. It is about 400 pulses. Meanwhile, the nine white square pattern has the smallest discharge current, but about 2000 pulses are applied to the panel to obtain a peak brightness. The interaction plot shows that when and are selected as 0.42 H and 150 ns, the circuit power loss can be minimized. Using the selected values, the transition time can be obtained as 500 ns from (12).
VI. EXPERIMENTAL RESULTS Fig. 13 shows the sustain voltage and inductor current waveforms. Before the panel polarity is inverted, the inductor currents are built up to about 35 A and they are recovered to the capacitors after changing the panel polarity. The clamping currents caused by parasitic capacitance of energy recovery switches are also shown in this figure. The measured waveforms in box shows that soft switching can be accomplished. Fig. 14 is the voltage waveforms of the panel electrodes accompanied by light waveforms when panel discharge for emitting light happens. As can be seen in this figure, the start voltage of the panel discharge is higher than series resonant type and more stable light waveform can be obtained especially at the nine white square image pattern. Fig. 15 is the power loss comparison plot. It shows that
LEE et al.: CURRENT INJECTION METHOD FOR AC PLASMA PANEL DISPLAY (PDP) SUSTAINER
Fig. 16.
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EMI radiation comparisons between two methods. (a) CIM. (b) Series resonant method.
the power loss is similar to that of series resonant type energy recovery circuit. It is desirable characteristic since this type has been known to be very effective method. The test result of EMI radiation at full white image pattern is as shown in Fig. 16. The newly developed method shows a lower EMI level at the 100 MHz–200-MHz band due to the reduction of surge current when the sustain switches conduct. VII. CONCLUSION In this paper, a new concept of energy recovery using current injection method (CIM) was proposed and verified with a 42 in PDP panel. Experimental results show that with the help of the buildup inductor current just prior to inverting the panel polarity, zero-voltage switching of switches can be achieved regardless of the parasitic resistance and it reduces the EMI caused by the surge current. The prototype driver circuit improves the light waveform uniformity and sustain voltage waveform while it has a desirable characteristic that power loss does not fall behind that of the series resonant method. Therefore, the proposed sustainer is expected to be suitable for a PDP sustaining driver requiring stable discharge characteristics. This concept can be applied to a parallel resonant driver and address recovery circuit as well as a series resonant driver. REFERENCES [1] A. Sobel, “Plasma displays,” IEEE Trans. Plasma Sci., vol. 19, pp. 1032–1047, Dec. 1991.
[2] H. Hirakawa, T. Katayama, S. Juroki, H. Nakahara, T. Nanto, K. Yoshikawa, A. Otsuka, and M. Wakitani, “Cell structure and driving method of a 25-in (64 cm) diagonal high-resolution color ac plasma display,” in Proc. Symp. Society for Information Display, vol. 29, 1998, pp. 279–282. [3] L. F. Webber, “Plasma display device challenges,” in Proc. Asia Display’98, 1998, pp. 15–27. [4] S. Y. Lin, C. L. Chen, and K. Lee, “Novel regenerative sustain driver for plasma display panel,” in Proc. IEEE PESC’98, Fukuoka, Japan, 1998, pp. 1739–1743. [5] L. F. Webber and K. W. Warren, “Power efficient sustain drivers and address drivers for plasma panel,” U.S. Patent 4 866 349, Sept. 1989. [6] M. Ohba and Y. Sano, “Energy recovery driver for a dot matrix AC plasma panel with a parallel resonant circuit allowing power reduction,” U.S. Patent 5 670 974, Sept. 1997. [7] H. B. Hsu, C. L. Chen, S. Y. Lin, and K. M. Lee, “Representative power electronics driver for plasma panel in sustain mode operation,” IEEE Trans. Ind. Electron., vol. 47, pp. 1118–1125, Oct. 2000.
Jun-Young Lee was born in Seoul, Korea, in 1970. He received the B.S. degree from Korea University, Seoul, Korea, in 1993, and the M.S. and Ph.D. degrees from Korea Advanced Institute of Science and Technology (KAIST), Taejon, Korea, in 1996 and 2001, respectively, all in electrical engineering. He is currently a Manager with the PDP Division, Samsung SDI Company Ltd., Chonan City, Korea. His research interests are in the area of power electronics, including ac/dc PFC converter topology design, converter modeling, soft-switching techniques, display driving circuits, PDP driving systems, and address energy recovery technology. Dr. Lee is a Member of the Korea Institute of Electrical Engineering (KIEE) and Korea Institute of Power Electronics (KIPE).
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Jin-Sung Kim was born in Seoul, Korea, in 1972. He received the B.S. and M.S. degrees from Seoul National University, Seoul, Korea, in 1996 and 1998, respectively. He is currently a Manager with the PDP Division, Samsung SDI Company Ltd., Chonan City, Korea, in charge of driver circuit development for PDPs. His research interests include display driving circuits, PDP driving methods, and address energy recovery circuits.
Nam-Sung Jung was born in Seoul, Korea, in 1962. He received the B.S. degree from Hanyang University, Seoul, Korea, in 1985, and the M.S. and Ph.D. degrees from Korea Advanced Institute of Science and Technology (KAIST), Taejon, Korea, in 1990 and 1999, respectively, all in electrical engineering. He is currently a General Manager with the PDP Division, Samsung SDI Company Ltd., Chonan City, Korea. His research interests are in the area of power electronics, including inverter and converter topology design, modeling, and soft-switching techniques in PDPs. Dr. Jung is a Member of the Korean Information Display Society (KIDS) and Korea Institute of Power Electronics (KIPE).
Bo-Hyung Cho (M’89–SM’95) received the B.S. and M.E. degrees from the California Institute of Technology, Pasadena, and the Ph.D. degree from Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, all in electrical engineering. Prior to his research at Virginia Tech, he worked for two years as a Member of Technical Staff, Power Conversion Electronics Department, TRW Defense and Space System Group, where he was involved in the design and analysis of spacecraft power processing equipment. From 1982 to 1995, he was a Professor in the Department of Electrical Engineering, Virginia Tech. In 1995, he joined the School of Electrical Engineering, Seoul National University, Seoul, Korea, where he is currently a Professor. His main research interests include power electronics, modeling, analysis, and control of spacecraft power processing equipment, power systems for space stations and space platforms, and distributed power systems. Dr. Cho received the 1989 Presidential Young Investigator Award from the National Science Foundation. He is a member of Tau Beta Pi.
