Essays /

13 High Efficiency And High Power Essay

Essay preview

High efficiency and high power factor single-stage
balanced forward-flyback converter
Yoon Choi, Moon-Hwan Keum, and Sang-Kyoo Han†

Jeong-il Kang

Power Electronics System Laboratory, POESLA
Kookmin University
Seoul, 136-702, Republic of Korea
E-mail : †[email protected]

Visual Display, R&D Team
Samsung Electronics. Co. Ltd.
Suwon, Republic of Korea
E-mail : [email protected]

Abstract— In this paper, a high efficiency and high power
factor single-stage balanced forward-flyback converter merging a foward and flyback converter topologies is proposed. The
conventional AC/DC flyback converter can achieve a good power factor but it has a high offset current through the transformer magnetizing inductor, which results in a large core loss and low power conversion efficiency. And, the conventional forward

converter can achieve the good power conversion efficiency with the aid of the low core loss but the input current dead zone near zero cross AC input voltage deteriorates the power factor. On the other hand, since the proposed converter can operate as the

forward and flyback converters during switch on and off periods, respectively, it cannot only perform the power transfer during an entire switching period but also achieve the high power factor due to the flyback operation. Moreover, since the current

balanced capacitor can minimize the offset current through the transformer magnetizing inductor regardless of the AC input
voltage, the core loss and volume of the transformer can be
minimized. Therefore, the proposed converter features a high efficiency and high power factor. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a prototype of 24W LED driver are presented.

between AC input and DC output. Even though the two-stage
configuration can provide the high power factor, good output regulation and excellent ripple voltage, it has several
significant disadvantages such as a large system size, high cost of production and low energy conversion efficiency [8].
Therefore, it is common that the two-stage driver is mainly
used for high power applications and single-stage driver is
adopted as a low power LED driver [9, 10].

(a) Single-stage flyback converter

Keywords—single stage; forward-flyback; LED driver;



Recently, light-emitting diodes (LEDs) have become one of
the most promising candidates for displays and lighting
applications, because LEDs have several favorable advantages such as a high efficiency, long life time and echo-friendliness. Therefore, traditional lighting devices such as a light bulb and fluorescent lamp tend to be replaced by LEDs [1, 2]. To drive LEDs, two types of drivers are generally used, that are a linear and switch-mode regulators [3]. Although the linear driver

features a simple circuit configuration, fast transient response and accurate current regulation, it has fatal drawbacks such as a low efficiency and serious heat generation. Therefore, the
switch-mode driver is widely used in LED applications due to its high efficiency and high power density [4, 5].
Meanwhile, since drivers for LED lightings have been
composed of two power conversion stages (ie. a power factor
corrector and isolated DC/DC converter) [6]. The first stage provides a near unity power factor and low total harmonic
distortion (THD) over an entire range of universal inputvoltage (90-270 Vrms) and the second DC/DC stage is used to provide a tight output regulation and galvanic isolation

978-1-4799-0224-8/13/$31.00 ©2014 IEEE

(b) Single-stage forward converter
Fig. 1. Conventional single-stage PFC converter circuits

Fig.1 shows conventional single-stage PFC (power factor
correction) LED drivers, which are well known as most costeffective solutions. Fig. 2 shows their transformer magnetizing inductor currents. As shown in this figure, the magnetizing
inductor offset current of flyback converter is larger than that of forward converter as followings
< iLM , flyback >=
< iLM , forward >= (1 +


n(1 - D )

N P 2 LM





Read more


-0224 -1 -121 -13 -1334 -169 -2007 -2013 -2058 -270 -29 -353 -362 -4799 -65 -702 -759 -8 /13 /lm 0.336 0.57 0.996 1 1.8 10 100uh 100v/div 11 116 12 13 1330 136 14 15 167 1a/div 2 2.36 2001 2006 2008 2009 200v/div 2010 2011 2014 2054 23 24w 26 264 264vrms 27 2a/div 2ea 2ms/div 2ts 3 31.00 348 357 4 42v 42v/0.57a 5 560 57 5us/div 6 60 7 735 754 8 8.07 82 822 823 824 825 826 827 88.71 9 90 90vrms 91.21 95 978 abovement abstract ac ac/dc accord accur achiev acknowledg across ad adopt advantag agenc aid along also although alway among analysi analyz annual apec2010 appli applic apr assum aug averag b balanc base basic batarseh bcm becom begin better block bo bong boundari bridgeless buck bulb byungcho c caid calcul candid cannot capacitor care case cb cd center charg chem chem-lin chen cheng cheol chiu choi chungyi chyi circuit clamp co combin common compar comparison compos conclus conduct confer configur confirm connect consid consist constant continu control conveni convent convers convert core correct corrector correspond cost costeffect cross current cycl d d1 d2 d3 dc dc-dc dc/dc dead decreas densiti depend design detail deterior determin develop devic diagram dimmabl diod disadvantag discharg discuss display distort divis [email protected] drawback drive driver ds dts due duti dvcb dvin dvo e e-mail earlier ecce2011 echo echo-friendli effici electrom electron emit employ energi enough entir epe epe-pemc equal equat especi even exact excel except expect experiment express f factor fast fatal favor featur feb fig fig.1 figur filter first flow fluoresc flyback follow forward forward-flyback forward-flyback-mix forwardflyback foward freewheel friendli futur galvan general generat give good guang h h0301 han hand harmon heat high high-effici higher howev hu hua hua-min huai huang huang-jen hwan ic ict id3 ideal ie ieee ii iid3 iii iin il ilm ilo implement increas induct inductor industri inform input inputvoltag insert introduct io ip isec isec/n isol itrc iv j jang jen jeong jeong-il [email protected] jin jin-bong jovanov jun jun-t june k kang keum key keyword kim kipe known kookmin korea kusuhara kwan kyoo l laboratori lamp larg larger lc led life light light-emit lim lin linear lm lo load long loss low low-pow lower ltd m m1 magnet mail main make maximum may meanwhil measur mention merg method mh might milan min ming ming-shian minim minimum ministri mix mode modul moment moon moon-hwan moreov mou msip much must n nakagawa nation nc nductanc near ninomiya nipa nov novel np ns nv nvo observ obtain offset one oper origin output p paper paramet peak pemc perform period perspect pesc pfc plan po poesla possibl power power-factor-correct pp present primari primarili principl problem proceed product program promis promot propos prototyp prove provid puls quantiti r rang ratio rato reach reason recent rectifi reduc refer reflect regardless regul releas repeat replac repres republ research respect respons result rippl ruan rule rustom samsung sang sang-kyoo sb scienc second secondari seen seoul sept serial serious sever shann shann-chyi shen shian shih shih-jen shin show shown side signific similar simpl sinc singl single-stag single-switch sinusoid size slope small smaller sn03a solut solv somewhat sourc southeastcon specif stage steadyst step step-down store stress subsequ suit sum superior supervis support suwon switch switch-mod swith symbol system t0 t1 t1-t0 t2 t2-t1 tabl tamotsu tcpdf team technolog tend term test thd theoret therefor though three thus tight time ting topolog total tradit tran transfer transform transient ts turn turn-on two two-stag type uf5404 uniti univers use v valid valu various vcb vcb-vo vd vds verifi versa via vice vin vin/lm vin/n vin/nvo visual vo vol vol.2 volt volt-second voltag volum vrms vsec vv w waveform wei well wide without wonseok woo word xiaojian xiaoyun xin xin-bo xu yan yang yang-guang yonghan yoon yoshito young yu yu-kang yungtaek zero zone zvs ~264vrms ~t1 ~t2 ái æn çç è ñ öv ø