Linear PFC regulator for LED lighting with the multi-level structure and low voltage MOSFETs.

Transcription

1 Linear PFC regulaor for lighing wih he muli-level srucure and low volage MOSFETs. Yuichi Noge Nagaoka Universiy of Technology Niigaa, Japan Jun-ichi Ioh Nagaoka Universiy of Technology Niigaa, Japan Absrac This paper proposes a linear PFC regulaor for lighing applicaions. The proposed circui is small in size because he circui srucure consiss of only semiconducors and resisors wihou any reacors and elecrolyic capaciors. The curren bypass circui which is conneced in parallel o he sring consiss of single MOSFET, wo zener diodes and wo resisors. The MOSFET is operaed in an acive sae by a selfbias circui. Thus, an exernal conroller and high volage gae drivers are no required. The proposed circui is experimenally validaed by using a 5 W prooype. From he experimenal resuls, he THD of inpu curren is 5.% and he power facor is.999. In addiion, he simulaion loss analysis demonsraes an efficiency of 9.6% for a 5. W prooype. I. INTRODUCTION lighing marke has grown rapidly due o he advanage of exended life-ime and improved luminance, wih he significan improvemen in he manufacuring process of s [][]. In he convenional AC driver, a converer is composed of a power facor correcion (PFC) recifier and a DC-DC converer. The convenional converer requires elecrolyic capaciors in he DC link, however, i is well known ha he life-ime of elecrolyic capacior is shorer han ha of. The converer wih disconinuous curren mode (DCM) operaion ha uses no elecrolyic capacior has been proposed o exend he life-ime of a converer [3-5]. However, he swiching and conducion losses of he semiconducor swich are increased due o he large peak curren. In addiion, he conduced EMI occurs in he inpu lines because of he swiched mode power supply (SMPS). Therefore, SMPS requires a bulky EMC filer o suppress elecromagneic noise. On he oher hand, a diode-clamped linear muli-level amplifier is proposed o obviae he need for passive EMI filers and improve efficiency in he AC moor drive [6]. The linear muli-level concep is possibly applied for an AC driver as a linear PFC regulaor [7-9]. These circuis are consruced from only semiconducors wihou any passive componens. However, high volage raing operaional amplifiers and MOSFETs are required. Hence, he losses will be increased due o he large quiescen curren of he operaional amplifiers and he high on-resisance of he MOSFETs. In his paper, a linear PFC regulaor for lighing wih he muli-level curren bypass circui is proposed. The proposed circui can be operaed by a self-bias circui wihou any exernal conrollers. In addiion, he volage raing of he MOSFETs can be reduced o V in_max /(n+) (n: Number of he series curren bypass circuis). Thus, he loss of he MOSFETs can be reduced. II. PROPOSED CIRCUIT Fig. shows he equivalen circui diagram. The recified inpu volage is applied o he srings. The curren bypass swiches S ~S 4 are conneced in parallel o he sring. The off sae volage of he swiches is clamped o he forward volage of parallel conneced s. The number of he required swiches is differen in each of he sring, which is depending on he on volage of he sring curren. Fig. shows he inpu curren waveforms of he AC side and he srings. The curren ampliude of he each sring is limied o consan value. Firsly, in he case ha he inpu volage V in is increased from he zero poin, all of he swiches are urned on. Then, he swiches S ~S 4 are urned off accordingly which is subjeced o inpu volage. As a resul, he inpu curren is increased in proporional o he inpu volage. Fig 3 shows loss reducion sraegy of curren regulaor by using muliple operaing poins. When he inpu volage is changing, he curren bypass swiches S ~S 4 will be operaed o vary he forward volage of he sring. Fig 4 shows he circui diagram of he firs sring in he case of 5 and srings. The curren bypass circui consiss of a single MOSFET, wo zener diodes and a single resisor. The operaion is as follows.

2 Table. Comparison of driver circuis. Proposed circui Sep-down Single swich (5 and srings) chopper (4) converer (4) Sequenial linear (8)(9) Inpu curren Sinusoidal Low power facor Sinusoidal Sinusoidal Lighing flicker Large Small Large Large Elemen deciding Elecrolyic life ime limi capacior Efficiency [%] 88.3, 9.6 > Reacor volume - Large Small - Capacior volume - Large Small - EMI filer - Required Required - Inpu power facor.995,.999.7~.8.98 >.95 Figure : Curren waveforms of he AC inpu and he srings. Figure : Equivalen circui diagram of he proposed driver in he case of 5 srings., The gae-source volage V gs of he MOSFETs is biased by ZD bias and R bias. The sauraion volage of he curren regulaor V on is lower han V ZDbias (6.8V > 3.V yp.). Therefore, S ~S 9 are urned on., The inpu volage V in becomes higher han he forward volage V F, so he s of V F are urned on. 3, V in - V F is applied o he drain-source of S (V ds ). In his area, S is operaed in an acive sae. 4, If V in becomes higher han V F + V F, S is compleely urned off due o he negaive bias of V gs. 5, The operaion of ~4 is repeaed unil V in reaches he maximum value. As a resul, he sring is operaed as a consan curren and variable volage. Table shows he circui parameers of he proposed circui a 5 and srings. Fig. 5 shows he equivalen circui diagram of MOSFET gae driver. The frequency response of a gae drive circui can be decided by a ime consan of a bias resisor R bias and inpu gae capaciances C iss. The cuoff frequency f cuoff of he gae driver is obained by (). Figure 3. Loss reducion of curren regulaor by using muliple operaing poins. fcu _ off = Rgae...() Rbias + nciss n where n is a number of series bypass MOSFETs. The frequency response should be deermined o be higher han wice of inpu power supply frequency. For example, by using he parameers in he Table (a), f cuoff becomes 7 khz. III. LOSS ANALYSIS A. Simulaion based analysis The loss analysis of he proposed circui is now discussed, which is carried ou using a PSPICE circui simulaor (Tina, Texas Insrumens). The losses are dominaed by he conducion loss of he curren source and he swiching loss of he MOSFETs. The swiching losses of he MOSFETs are varied wih he dv/d rae of V in. The loss analysis shows an efficiency of 9.6 % a srings including he diode recifier.

3 (a) 5 srings. (PMOS) (b) srings. (NMOS) Figure. 4. Circui diagram of he firs sring. Table. Circui parameers for simulaion and experimen. (a) 5 srings. LUW_JNSH.EC (OSRAM) V F=3.V, I F= ma, 36-series FET No. No. No. 3 MOSFET ZD gae, ZD bias R bias, R gae 5LPSS (ON semiconducor) V ds=-5 V, R on=8 Ω, C iss=7.4 pf V z=6.8 V MΩ.. No. 4 Zener diode Resisors Curren regulaor Diode bridge V in MOSFET ZD gae, ZD bias R bias, R gae NSI45TG (ON semiconducor) I sr= ma, V on=3.5 V DF8SA (Vishay) AC V, 5 Hz (b) srings. LUW_JNSH.EC (OSRAM) V F=3.V, I F= ma, 4-series SSM3K5F (Toshiba) V ds=3 V, R on=4 Ω, C iss=7.8 pf V z=6.8 V MΩ Sring number (a) 5 srings Curren source R shun Curren regulaor 6.5 Ω LM86-ADJ (Texas Insrumens) I sr= ma, V on=3. V Figure 5. Equivalen circui of gae driver. B. Calculaion based analysis Fig. 7 shows he semiconducor loss of he firs sring. The haching areas indicae he losses of he swiches and he curren regulaor. Fig. 8 shows an example of he loss (b) srings Figure 6. Loss disribuion of each sring. waveforms of he curren bypass MOSFETs and curren regulaive diode (CRD). During o, S is operaed in acive region. The ime period of he acive region is given by ().

4 T Inpu volage 5V/div T a V in_max T T 5 T T a x= VFx...() = sin ω V in _ max (a) 5 srings where ω is a angular frequency of he inpu volage, V in_max is a peak inpu volage, V fx is a forward volage of he s shown in Fig. 4. The acive region loss of he MOSFETs are expressed as (3) n a+ Pswa = 4 f _ max sin ( + ) _ V Isr Vin ω d a linear a VFx (3) in a x= where f Vin is a frequency of he inpu volage, he firs erm shows he inegraed value of he inpu volage, he second erm shows he oal volage of s. The conducion loss of he MOSFETs are expressed as (4). V F9 V F8 V F7 V F6 V F5 V F4 V F3 V F V F V F P Regulaor P sw9 P sw8 P sw7 P sw6 P sw4 P sw3 P sw P sw Pswa = 4 f ( ) _ cond V RonIsr n in + a...(4) The acive region loss of he curren regulaor is expressed as (5) n n+ Pcs _ linear = 4 fv Isr Vin d n+ n+ VFx in _ max sinω ( ) (5) n+ x = The conducion loss of he curren regulaor is expressed as (6). Pcs _ cond = 4 fv I srvon( n ) in +...(6) Fig. 9 shows he loss comparison resuls of he firs sring by comparing beween he calculaion and simulaion. The calculaed loss is slighly higher han ha of simulaion. The reason is ha forward curren of he is flowed a he peak of V ds of he MOSFET in simulaion. Thus, he curren is P sw5 (b) srings Figure 7. Semiconducor losses. Sring curren No. Forward volage of (V Fx ) and CRD Power loss of MOSFET T T P s V F ma/div V/div.W/div Time [ms] Figure 8: Simulaion waveforms. divided ino a MOSFET and a. Therefore, he drain curren of he MOSFET is decreased. Fig. shows he loss comparison beween he 5 sring ype and he sring ype. The acive region loss can be decreased by increasing he number of bypass circuis. When he number of bypass circuis increased o 9, he acive region loss is 46% decreased. IV. EXPERIMENTAL RESULTS Table 3 shows he specificaion of he proposed circui and he sample produc of sep-down chopper circui. V F P s4 V CRD Figure 9. Loss disribuion of he firs sring. (5 srings)

5 4 6 8 Figure. Swich loss comparison of sring No.. Table 3. Specificaion of 5 srings prooype and sample produc. Proposed circui Sep-down chopper (5 srings) (Sample produc) Inpu power [W] 7.8 W. W (a) Inpu volage and curren Luminous flux [lm] 75 8 Luminous efficiency [lm/w] Power facor (a) 5 srings. (b) srings. Figure. Prooype of experimen. Fig. shows a prooype. The proposed circui can be mouned on a single sided PCB wih no holes. The circui parameers are as same as shown in Table. Fig. shows he inpu curren and he sring curren waveforms obained by using he 5 srings ype. The inpu acive power is 7.8 W. Good sinusoidal waveform is achieved in he inpu curren. The inpu curren THD and he power facor are 9.8% and.995, respecively. Fig. 3 shows he inpu volage and curren waveforms obained by using sep-down chopper circui. The inpu curren waveform is disored by capacior inpu diode recifier. (b) Sring curren Figure. Experimenal waveforms of he proposed circui. Fig. 4 shows conducion noise in he proposed circui and he sep-don chopper circui. Red line is he limi of CISPR Conducion noise in he sep-down chopper circui is aenuaed o -9 db lower han he limied line. On he oher hand, conducion noise in he proposed circui is almos as same as he background noise. Therefore, he conducion noise can be reduced by using he proposed circui. Fig. 5 shows he volume of each componen ha be composed of he passive componens, semiconducors and noise filers. The componen volume of he proposed circui is 83% smaller han he sample produc. Fig. 6 shows he inpu curren and he sring curren waveforms obained by using he srings ype. The inpu

6 Figure 3. Experimenal waveforms of he sep-down chopper circui. Figure 6. Experimenal waveforms. ( srings) (a) Proposed circui (5-srings) (b) Sep-down chopper circui Figure 4. Conduced emission specrum. Figure 7. Experimenal resuls of sring curren Figure 5. Volume of circui componen. acive power is 5 W. The inpu curren disorion becomes lower han he 5 srings ype. The inpu curren THD and he power facor are 5.% and.999, respecively. Fig. 7 shows he curren waveforms of he srings. A conducion ime of each sring is conrolled by he number of curren bypass circuis. In addiion, he sring curren is limied a ma by he curren regulaor. Fig. 8 shows he drain-source volage waveforms of he firs sring MOSFETs. In he ransien of V ds, he MOSFET is operaed in sauraion region. Then, in he consan V ds area, i is operaed in acive region. In addiion, he maximum V ds is limied by V F of he parallel conneced s. Therefore, low volage raing (3 V) MOSFETs can be used o achieve high efficiency. Fig. 9 shows he inpu curren harmonics from he experimenal resuls. I can be confirmed ha he low order harmonic componens in he inpu curren are lowered by increasing he number of he curren bypass circui.

7 V. CONCLUSIONS This paper proposed a linear PFC regulaor for lighing wih a new muli-level curren bypass circui. Feaures of he proposed circui are he implemenaion of low volage of MOSFETs, no elecrolyic capaciors are required and a simple gae bias circui wihou any exernal conrollers. The experimenal resuls have confirmed he validiy of he proposed circui srucure. Figure 8: Experimenal resuls of V ds and V on.. REFERENCES [] Bessho Makoo, Shimizu Keiichi : Trends in Lighing and Toshiba s approach, Toshiba review, Vol. 65, No. 7 pp. -7 () [] M. S. Shur and A. Zukauskas, Solid-sae lighing: Toward superior illuminaion, Proceedings of he IEEE, Vol. 93, No., pp , Oc. 5. [3] H. Broeck, G. Sauerlander, and M. Vend, Power driver opologies and conrol schemes for s, IEEE Applied Power Elecronics Conference and Exposiion (APEC), pp , 7. [4] Takashi Kunimasu, Keia Kawabe, Toshifumi Ishida : Developmen of Driver IPD for Lighing, Panasonic Technical Jorunal, Vol. 58, No., pp. 8-3 () [5] B. Wang, X. Ruan, K.Yao, and M.Xu A Mehod of Reducing he Peak-o-Average Raio of Curren for Elecrolyic Capacior-Less AC DC Drivers, IEEE Transacions on Power Elecronics, vol. 5, no. 3, pp. 59 6, Mar.. [6] Hideaki Fujia, A High-Efficiency Diode-Clamped Linear Amplifier, The ransacions of he Insiue of Elecrical Engineers of Japan. D A publicaion of Indusry Applicaions Sociey, Vol. 7, No. pp. 9-6 (7) [7] R. Dayal, K. Modepalli, L. Parsa A direc AC driver wih high power facor wihou he use of passive componens, IEEE Energy Conversion Congress and Exposiion (ECCE), pp ,. [8] Sequenial Linear Driver CL88, Superex inc., DSFP- CL88,, Available: hp:// [9] S. Lynch, B. Choy, K. C, MULTIPLE STAGE SEQUENTIAL CURRENT REGULATOR, Inernaional Paen, WO /4495 A, 8 Oc Figure 9. Inpu curren harmonics.