RECHARGEABLE batteries are extensively applied in

Transcription

1 105 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 45, NO. 3, MAY/JUNE 009 Implementatin and Analysis f an Imprved Series-Laded Resnant DC DC Cnverter Operating Abve Resnance fr Battery Chargers Ying-Chun Chuang, Yu-Lung Ke, Senir Member, IEEE, Hung-Shiang Chuang, and Hung-Kun Chen Abstract The well-established advantages f resnant cnverters, including simplicity f circuit cnfiguratin, ease f the cntrl scheme, lw switching lsses, and lw electrmagnetic interference, amng thers, have led t their attracting mre interest. This wrk develps a highly efficient battery charger with an imprved series-laded resnant cnverter fr renewable energy applicatins t imprve the perfrmance f traditinal switching-mde charger circuits. The switching frequency f the imprved series-laded resnant battery charger was at cntinuus cnductin mde. Circuit peratin mdes are determined frm the cnductin prfiles. Operating equatins and perating thery are als develped. This study utilizes the fundamental wave apprximatin and a battery equivalent circuit t simplify the circuit analyses. The mean charging efficiency f the prpsed tplgy is as high as 87.5%. Index Terms Battery charger, series-laded resnant cnverter. I. INTRODUCTION RECHARGEABLE batteries are extensively applied in varius applicatins such as cellular phnes, laptp cmputers, uninterruptible pwer supplies, electrical vehicles, renewable energy strage systems, and thers 1 4. Such equipment cntinuusly cnsumes electrical energy, and they require a charging circuit in a rechargeable battery 5 9. Fr several years, mst battery chargers available n the market were f linear-mde cnverters, in which an active pwer element regulates the utput vltage. A linear-mde cnverter with an active pwer element is generally used as a variable resistance t dissipate unwanted r excess vltage Such an arrangement results in the dissipatin f large amunts Paper ICPSD-08-8, presented at the 008 IEEE/IAS Industrial and Cmmercial Pwer Systems Technical Cnference, Clearwater Beach, FL, May 4 8, and apprved fr publicatin in the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Industrial and Cmmercial Pwer Systems Cmmittee f the IEEE Industry Applicatins Sciety. Manuscript submitted fr review May 10, 008 and released fr publicatin December 4, 008. Current versin published May 0, 009. Y.-C. Chuang is with Department f Electrical Engineering, Kun Shan University, Tainan 71003, Taiwan ( chuang@mail.ksu.edu.tw). Y.-L. Ke is with Department f Electrical Engineering and the Institute f Electrical Engineering, Kun Shan University, Tainan 71003, Taiwan ( yulungke@ms5.hinet.net). H.-S. Chuang is with Department f Electrical Engineering, Ka Yuan University, Kahsiung 81, Taiwan ( c347901@ms5.hinet.net). H.-K. Chen is with Department f Electrical Engineering, Sunnwealth Electric Machine Industry Cmpany, Kahsiung 80, Taiwan ( a @yah.cm.tw). Clr versins f ne r mre f the figures in this paper are available nline at Digital Object Identifier /TIA f pwer in the active pwer element, ptentially reducing the charging efficiency t as lw as 50%. The basic requirements f battery charger circuits are smallness and high efficiency. Their lw efficiency has therefre prevented linear-mde cnverters frm being applied t battery chargers, and since the early 1970s, the uptake f switch-mde pwer cnverters have been increasing. Unlike linear-mde cnverters, switch-mde pwer cnverters use active pwer switches t perate in either the saturatin regin r the cutff regin. Since either regin will lead t a lw switching vltage r a lw switching current, pwer can be cnverted with higher efficiency using a switchmde pwer cnverter as a battery charger circuit Accrdingly, switch-mde battery chargers with efficiencies f greater than 70% can be easily designed at lw cst and with relatively small size and light weight. In all switch-mde pwer cnverters, the cntrllable switches are perated in a switch mde in which they turn n and ff the entire charging current during each switching perid. Hence, the cntrllable switches are subjected t high switching stresses and high switching pwer lsses that increase linearly with the switching frequency f the battery chargers. Anther significant shrtcming f the switch-mde peratin is the electrmagnetic interference (EMI) that is generated by the large di/dt and dv/dt that are assciated with a switch-mde peratin. Unlike switch-mde cnverters, the cmbinatin f prper cnverter tplgies and switching strategies can slve the prblems f switching stresses, switching pwer lsses, and EMI, by turning n and ff each f the cnverter switches when either the switch vltage r the switch current is zer. A new class f dc dc pwer cnverters was then intrduced in the late 1980s. This grup f tplgies is knwn as sft-switching resnant cnverters. The ptential advantage f the sft-switching resnant cnverters ver linear-mde and switch-mde cnverters is the reduced switching pwer lsses and, cnsequently, higher pwer density, with maintained high efficiency. Additinally, the higher switching frequency causes such cnverters t exhibit shrter transient respnses The literature describes numerus sft-switching techniques t imprve the charging behavir f resnant dc dc cnverters, amng which, the class-d half-bridge series-laded resnant cnverter designed fr battery chargers is the simplest and has varius advantages. One f the main advantages f class-d halfbridge series-resnant cnverters is the lw vltage acrss the active pwer switches, which equals half f the input supply vltage 6. This makes them suitable fr high input /$ IEEE Authrized licensed use limited t: Ka Yuan University. Dwnladed n May 30, 009 at 1:5 frm IEEE Xplre. Restrictins apply.

2 CHUANG et al.: IMPLEMENTATION AND ANALYSIS OF CONVERTER OPERATING ABOVE RESONANCE 1053 Fig. 1. Blck diagram f dc dc resnant cnverter fr battery chargers. vltage applicatins. Furthermre, lw-vltage active pwer switches can be used. Mrever, class-d half-bridge seriesresnant cnverters can perate safely at n lad because n current flws thrugh the resnant circuit. Frm a circuit standpint, a dc dc resnant cnverter fr battery chargers can be described in terms f three majr circuit blcks, as shwn in Fig. 1. They are the dc ac input inversin circuit, the resnant energy buffer tank circuit, and the ac dc utput rectifying circuit. The dc ac inversin is usually achieved using varius switching netwrk tplgies. The resnant tank, which acts as an energy buffer between the input and the utput, is typically synthesized using a lssless frequency-selective netwrk. The purpse f this netwrk is t regulate the energy flw frm the surce t the lad. Finally, ac dc cnversin is achieved by incrprating rectifier circuits at the utput sectin f the cnverter. Hwever, the utput vltage V f the class-d halfbridge series-laded resnant cnverter cannt exceed half f the input vltage V s /:V (V s /). In the attempts t vercme this shrtcming, many effrts have been made t design a system with fewer cmpnents and supprt a high utput vltage tplgy fr the battery charger, s as t prvide a cmpetitive characteristic in the cnsumer market. This paper presents a relatively simpler charger tplgy fr the chargeable batteries based n the imprved class-d half-bridge series-resnant cnverter, which is the mst ecnmical circuit tplgy that is frequently emplyed t drive pwer electrnic equipment. In the prpsed apprach, a resnant netwrk with a vltage-dubler rectifier is interpsed between the ac utput stage and the chargeable battery. Based n the prpsed class-d half-bridge series-resnant cnverter, the battery charger can prvide high charging current, lw switching lsses, and high efficiency. The utline f this paper is listed as fllws. Sectin II describes the presented class-d half-bridge series-laded resnant cnverter with a vltage-dubler rectifier fr a battery charger. Sectin III illustrates the perating characteristics f the presented class-d half-bridge series-laded resnant cnverter with a vltage-dubler rectifier fr a battery charger. The experimental results are shwn in Sectin IV. The mst favrable advantages are summarized in Sectin V. II. CIRCUIT DESCRIPTION Fig. shws in detail the circuit f the class-d half-bridge series-laded resnant cnverter with a vltage-dubler rectifier fr a battery charger. It has tw bidirectinal pwer switches M 1 and M, a series-resnant circuit, and a current-driven highfrequency vltage-dubler rectifier. The tw capacitrs C 1 and C n the input are large and split the vltage f the surce. Each bidirectinal pwer switch has an active pwer switch and an antiparallel dide. The active pwer switches are driven Fig.. Imprved series-laded resnant cnverter with a vltage-dubler rectifier fr battery chargers. Fig. 3. Idealized vltage and current wavefrms. by nnverlapping rectangular-wave trigger signals v GS1 and v GS with dead time. The bidirectinal switches M 1 and M are alternatively turned n and ff, with a duty rati f 50% r slightly less. The dead time is the perid in which bth switching devices are ff. The basic functin f the class-d half-bridge series-laded resnant cnverter is t use the pwer switches t generate a square-wave vltage fr v a.fig.3shws the idealized vltage and current wavefrms in the class-d halfbridge series-laded resnant cnverter with a vltage-dubler Authrized licensed use limited t: Ka Yuan University. Dwnladed n May 30, 009 at 1:5 frm IEEE Xplre. Restrictins apply.

3 1054 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 45, NO. 3, MAY/JUNE 009 Fig. 4. Equivalent circuit f Mde I. Fig. 5. Equivalent circuit f Mde II. rectifier fr a switching frequency f s that exceeds the resnant frequency f. Operatin abve resnance is preferred because the pwer switches turn n at zer current and zer vltage; thus, the freewheeling dides d nt need t have very fast reverse-recvery characteristics. Therefre, nly tw dides are required instead f a bridge rectifier as shwn in Fig.. During the psitive half-cycle f the resnant tank current, the pwer is supplied t the battery thrugh dide D r1.during the negative half-cycle f the resnant tank current, the pwer is supplied t the battery thrugh dide D r, increasing the efficiency abve that f a traditinal bridge rectifier. The class-d half-bridge series-laded resnant cnverter with a vltage-dubler rectifier fr battery chargers is analyzed based n the fllwing assumptins. 1) The switching elements f the cnverter are ideal, such that the decline in frward vltage in the ON-state resistance f the switch is negligible. ) The equivalent series resistance f the capacitance and stray capacitances is negligible. 3) The characteristics f passive cmpnents are assumed t be linear, time invariant, and frequency independent. 4) The filter capacitr C at the utput terminal is usually very large, and therefre, the utput vltage acrss the capacitr can be treated as a dc vltage in each switching cycle. 5) The lad quality factr f the imprved class-d halfbridge series-laded resnant cnverter is sufficiently high that the resnant current i Lr is sinusidal. The steady-state peratin f the imprved series-lad resnant charging circuit in ne switching perid includes fur mdes. A. Mde I: (Between ω t 0 and ω t 1 ) The peridic switching f the resnant energy tank vltage between +V s / and V s / generates a square-wave vltage acrss the input terminal. Since the utput vltage is assumed t be a cnstant V, the input vltage t the vltage-dubler rectifier v b is V / when i Lr is psitive and is V / when i Lr is negative. Hence, Fig. 4 shws the equivalent circuit f the class-d half-bridge series-laded resnant cnverter with a vltage-dubler rectifier fr the battery charger circuit in Fig.. Befre ω t 0, the freewheeling dide D 1 is turned n and cnducts a current that equals the resnant tank current i Lr ;the active pwer switch S 1 is excited. At the instant ω t 0, the resnant tank current i Lr reverses and naturally cmmutates frm dide D 1 t the pwer switch S 1.In this mde, the pwer switches turn n naturally at zer vltage and at zer current. Accrdingly, the active pwer switch is negative after turn-n and psitive befre turn-ff. The initial cnditin f the capacitr C r is V c. Then, the instantaneus resnant inductr current and the vltage acrss C r can be evaluated, where the angular resnance frequency ω =πf = 1/ LrCr and the characteristic impedance Z = Lr/Cr, respectively, i Lr (t) = 1 Z V c V sin ω t (1) cs ω t. () V c V V cr (t) = V s V The current in the switches is turned n at zer vltage and zer current t eliminate turn-n lsses, but the switches are turned ff at nnzer current; therefre, turn-ff lsses may exit. Frtunately, small capacitrs can be placed acrss the switches t act as snubbers t eliminate turn-ff lsses. B. Mde II: (Between ω t 1 and ω t ) At ω t 1, befre the half-cycle f the current i Lr scillatin ends, the switch S 1 is frced t turn ff, frcing the psitive current t flw thrugh the bttm freewheeling dide D. Fig. 5 shws the equivalent circuit. The negative dc vltage applied acrss the resnant tank causes the current that flws thrugh the dide t g quickly t zer at ω t. During this interval, the inductr current i Lr is expressed as fllws, where I L1 is the initial current in the inductr i Lr : i Lr (t) = 1 Z V V c1 sin ω (t t 0 ) + i L1 cs ω (t t 0 ) I L1 = i Lr (t 1 )= 1 Z V c V sin β. (3) The vltage v cr acrss the resnant capacitr C r is given by (4), where V c1 is the initial vltage acrss the capacitr C r V cr (t) =V c1 + V V c1 1 cs ω (t t 0 ) + I L1 ω sin ω (t t 0 ) V c1 = V cr (t 1 )= V s V V c V cs β. (4) C. Mde III: (Between ω t and ω t 3 ) Befre ω t, the trigger signal v gs excites the active pwer switch S. When the inductr current i Lr changes directin, the freewheeling dide D is turned ff, and the active pwer switch S is turned n. Fig. 6 shws the equivalent circuit. Authrized licensed use limited t: Ka Yuan University. Dwnladed n May 30, 009 at 1:5 frm IEEE Xplre. Restrictins apply.

4 CHUANG et al.: IMPLEMENTATION AND ANALYSIS OF CONVERTER OPERATING ABOVE RESONANCE 1055 Fig. 6. Equivalent circuit f Mde III. Fig. 8. Simplified equivalent circuit f imprved class-d half-bridge seriesladed resnant cnverter. Equatin (8) gives the vltage v cr f the capacitr v cr (t) = V s + V V c3 + V cs ω (t t 3 ) + I L3 Z sin ω (t t 3 ). (8) Fig. 7. Equivalent circuit f Mde IV. Mde III begins at ω t, when the dide D is pen circuited as shwn in Fig. 6, prducing a resnant stage between inductr L r and capacitr C r. The zer-vltage turn-n f the active pwer switch S is achieved because the current has already flwed thrugh the freewheeling dide D befre the lwer switch S is turned n. The inductr L r and capacitr C r resnate. Then, the inductr current i Lr and the capacitr vltage v cr f the resnant circuit are as given by (5) and (6), where V c is the initial vltage acrss the resnant capacitr C r i Lr (t) = 1 Z V c + V v cr (t) = + V sin ω (t t ) (5) V c + V V c = v cr (t ) = v c1 + V V c1 (1 cs ω α) cs ω (t t ) + I L1 sin ω α. (6) ω At the instant ω t 3, the active pwer switch S is turned ff, and Mde III ends. D. Mde IV: (Between ω t 3 and ω t 4 ) A turn-ff trigger signal is applied t the gate f the active pwer switch S. Then, the inductr current naturally cmmutates frm the active pwer switch S t the freewheeling dide D 1. Fig. 7 shws the equivalent circuit. Applying Kirchhff s law t Fig. 7 yields the inductr current i Lr as given by (7), where the initial current I L3 in the inductr L r is given by (5) at t = t 3 i Lr (t) = 1 Z V c3 + V sin ω (t t 3 ) + I L3 cs ω (t t 3 ). (7) Then, the initial inductr current can be written as fllws: I L3 = i Lr (t 3 )= 1 Z V c + V sin ω (t 3 t ). Equatin (6) yields the initial value V c3 in the previus mde t yield the fllwing: V c3 = V cr (t 3 ) = + V V c + V cs ω (t 3 t ). When the driving signal V gs1 again excites the active pwer switch S 1, this mde ends, and the peratin returns t mde I in the subsequent cycle. Rather than using a bridge rectifier fr the utput stage, tw dides, as shwn in Fig., can be used. This circuit cnfiguratin is knwn as a vltage-dubler rectifier. During the psitive half-cycle f the inductr current, the pwer is supplied t the battery thrugh dide D R1. During the negative halfcycle f the inductr current, the pwer is supplied t the battery thrugh dide D R. III. OPERATING CHARACTERISTICS Fig. shws the imprved class-d half-bridge series-laded resnant cnverter with a vltage-dubler rectifier fr battery chargers. The switching frequency f the active pwer switches is assumed t exceed the resnant frequency such that the resnant current is cntinuus. Given a large capacitive filter at the utput terminal, the utput vltage may be assumed t be cnstant. The charger circuit in Fig. can be simplified t the schematic circuit shwn in Fig. 8 t facilitate the analysis f the peratin f the class-d half-bridge series-laded resnant cnverter with a vltage-dubler rectifier. Since the utput vltage is assumed t be a cnstant V, then the input vltage t the vltage-dubler rectifier v b is V / when i Lr is psitive and is V / when i Lr is negative. The imprved class-d half-bridge series-laded resnant cnverter with a vltage-dubler rectifier fr battery chargers is analyzed based n the fundamental frequency f the Furier series f the vltages and currents. Then, the utput vltage v b f the vltage-dubler rectifier is given by a Furier series which is given by v b (t) = n=1,3,5,... V nπ sin(nωt). (9) Authrized licensed use limited t: Ka Yuan University. Dwnladed n May 30, 009 at 1:5 frm IEEE Xplre. Restrictins apply.

5 1056 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 45, NO. 3, MAY/JUNE 009 Fig. 9. Equivalent ac circuit f imprved class-d half-bridge series-laded resnant cnverter fr battery chargers. Equatin (10) gives the fundamental cmpnent f vltage v b v b1 = V sin(ωt). (10) π The currents at the utput f the vltage-dubler rectifier i DR1 and i DR are the full-wave rectified frms f the inductr current i Lr. Hence, the average f the rectified inductr current i Lr equals the utput charging current I. If the inductr current i Lr is apprximated as a sine wave f amplitude I LM1, then the average value f charging current I is given by I = L LM1. (11) π The utput resistance in this equivalent circuit is determined frm the rati f vltage t current at the vltage-dubler rectifier. The fllwing thus defines resistance: R e = V b1 = 4 I LM1 π V. (1) I The relatinship between the input and utput is apprximated by an ac circuit analysis using the fundamental frequencies f the vltage and current equatins. Fig. 9 shws the equivalent ac circuit. T achieve resnant peratin, the resnant circuit must be underdamped. That is, Lr R e. (13) C r The input part f the imprved class-d half-bridge seriesladed resnant cnverter fr battery chargers has a dc input vltage surce V s and a set f bidirectinal pwer switches. The active pwer switches are cntrlled t generate a square-wave vltage v a. Since a resnant circuit frces a sinusidal current, nly the pwer f the fundamental cmpnent is transferred frm the input surce t the resnant circuit. Therefre, nly the fundamental cmpnent f this cnverter needs be cnsidered. The fllwing defines a vltage transfer functin f this imprved cnverter: V V s = 1 1+( XL X C R e ). (14) The reactance X L and X C depend n the switching frequency. Accrdingly, the utput vltage can be regulated by changing the switching frequency f the cnverter. The nrmalized utput vltage V /V s is pltted as a functin f f s /f at varius laded quality factrs Q (Fig. 10). The utput vltage is Fig. 10. Nrmalized utput vltage at varius switching frequencies. maximal at the resnant frequency f. This figure indicates that the imprved half-bridge series-laded resnant cnverter has an utput f twice the peak value f the traditinal half-bridge series-laded resnant cnverter. The energy that flws int the battery during the interval ω t 0 ω t ω t 1 is given by W 1 = t 1 = V ω 1 Z V B i Lr(t) dt V c V (1 cs β). (15) The fllwing term is defined: A 1 Z V c V (1 cs β). (16) The energy that flws int the battery during the interval ω t 1 ω t ω t is given by W = t t 1 0 = V V i Lr(t ) dt t t 1 0 { 1 Z V S V V c1 sin ω t } + I L1 cs ω t dt = V { 1 V S ω Z V } V c1 (1 cs α)+i L1 sin α. (17) Substituting (3) and (4) int the afrementined equatin yields W = V { V S + 1 ( ω Z Z V c V 1 ( Z V c V + 1 Z V c V ) (1 cs β) ) (1 cs α) sin β sin α }. (18) Authrized licensed use limited t: Ka Yuan University. Dwnladed n May 30, 009 at 1:5 frm IEEE Xplre. Restrictins apply.

6 CHUANG et al.: IMPLEMENTATION AND ANALYSIS OF CONVERTER OPERATING ABOVE RESONANCE 1057 The fllwing term is defined: { B Z + A 1 Z ( V c V + 1 ( Z V c V ) (1 cs α) ) sin β sin α }. (19) Hence, the ttal energy that flws int the battery during the interval ω t 0 ω t ω t is determined by W = W 1 + W = V (A + B). (0) ω The energy frm the input dc surce during the interval ω t 0 ω t ω t 1 is given by Fig. 11. Trigger signals f pwer switches. W S1 = V S t 1 0 i Lr (t) dt = V S ω A. (1) The energy frm the input dc surce during the interval ω t 1 ω t ω t is given by Fig. 1. Vltage and current wavefrms f active pwer switch S 1. W S = V S t t 1 0 i Lr (t ) dt = V S ω B. () Accrdingly, the energy that is generated by the input dc surce is given by W S = W S1 + W S = V S (A B). (3) ω Fr a lssless system, these tw energies are equal in the steady state. Therefre, (4) gives the utput vltage A B V = V S A + B. (4) The mst imprtant advantage f the imprved series-laded resnant cnverter is that the maximum utput vltage V in Fig. can apprach the input dc surce vltage V S, unlike in a traditinal series-laded resnant cnverter where V can nly apprach 0.5V S. Restated, the imprved series-laded resnant cnverter must switch nly half as much current fr the same V S and utput pwer. This advantage makes the imprved series-laded resnant cnverter the preferred cnfiguratin fr rapidly charging battery applicatins. IV. EXPERIMENTAL RESULTS The input f the prpsed imprved series-laded resnant cnverter was cnnected t a system that cmprised a dc surce with an utput vltage f 0 V. A prttype f the battery charger with imprved series-laded resnant tplgy was established in a labratry t verify the functinal peratins. The develped charger circuit is applied t a 1-V 48-Ah lead-acid battery. The cnditins f the experiment were as fllws: switching frequency f s =4kHz, resnant frequency f r = khz, charging current I =8 A, charging vltage V BA =15 V, and the pen-circuit vltage f battery V c = Fig. 13. Fig. 14. Resnant vltage and current wavefrms. Input and utput vltage wavefrms f resnant tank. 11 V. Under these perating cnditins, the tw parameters f the imprved series-laded resnant cnverter are as fllws: C r =3. μf L r =16μH. The wavefrms were measured using a digital multimeter. Fig. 11 shws the wavefrms f the trigger signals V GS1 and V GS. Fig. 1 shws the vltage and current wavefrms f the active pwer switch S 1. Fig. 13 shws the wavefrms f the resnant vltage v cr and the resnant current i Lr.Fig.14shws the input and utput vltage wavefrms f the resnant tank terminals. Fig. 15 shws the vltage and current wavefrms f the vltage-dubler rectifier dide D R1.Fig.16shwsthe vltage variatin curve f the battery. The terminal vltage f the battery rises frm 10.5 t 15.5 V in 500 min. Figs. 17 and 18 shw the charging current and the charging efficiency, Authrized licensed use limited t: Ka Yuan University. Dwnladed n May 30, 009 at 1:5 frm IEEE Xplre. Restrictins apply.

7 1058 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 45, NO. 3, MAY/JUNE 009 presented the use f a battery charger with an imprved seriesladed resnant tplgy in the charging test f a lead-acid battery charger t demnstrate the effectiveness f the develped apprach. The circuit efficiency f the verall charging prcess exceeds 83%. Accrdingly, the charging efficiency can be imprved using an imprved series-laded resnant cnverter with vltage-dubler rectifier tplgy. Favrable perfrmance is btained at lwer cst and with fewer cmpnents. Fig. 15. Vltage and current wavefrms f vltage-dubler rectifier dide D R1. Fig. 16. Fig. 17. Fig. 18. Battery vltage during charging perid. Charging current during charging perid. Charging efficiency during charging perid. respectively. The charging current I declines as the vltage V f the battery increases. The charging current takes 330 min t fall belw 6.8 A. The minimal and maximal efficiencies f the battery charging circuit are abut 83% and 95%, respectively, and the mean charging efficiency f the charger is 87.5%. V. C ONCLUSION This wrk has designed an imprved series-laded resnant cnverter with a vltage-dubler rectifier fr battery chargers. The circuit structure is simpler and cheaper than ther cntrl mechanisms which require many cmpnents. This paper has REFERENCES 1 J. P. Nelsn and W. D. Blin, Basics and advances in battery systems, IEEE Trans. Ind. Appl., vl. 31, n., pp , Mar./Apr C. W. Seitz, Industrial battery technlgies and markets, IEEE Aersp. Electrn. Syst. Mag., vl. 9, n. 5, pp , May J. Ripley, M. T. Ansari, and J. Dehn, Battery chargers and batteries fr DC and AC back-up pwer systems, in Prc. IEEE Ind. Appl. Sc. 48th Annu. Petrleum Chem. Ind. Cnf., Sep. 001, pp A. Affanni, A. Bellini, G. Franceschini, P. Guglielmi, and C. Tassni, Battery chice and management fr new-generatin electric vehicles, IEEE Trans. Ind. Electrn., vl. 5, n. 5, pp , Oct K. Kutluay, Y. Cadirci, Y. S. Ozkazanc, and I. Cadirc, A new nline state-f-charge estimatin and mnitring system fr sealed lead-acid batteries in telecmmunicatin pwer supplies, IEEE Trans. Ind. Electrn., vl. 5, n. 5, pp , Oct H. M. H. Abe, H. Sakamt, and K. Harada, A nncntact charger using a resnant cnverter with parallel capacitr f the secndary cil, IEEE Trans. Ind. Appl., vl. 36, n., pp , Mar./Apr J. Martynaitis, Discussin f micrprcessr-cntrlled new class f ptimal battery chargers fr phtvltaic applicatins, IEEE Trans. Energy Cnvers., vl., n., pp , Jun J. Lee, S. J, S. Chi, and S. B. Han, A 10-kW SOFC lw-vltage battery hybrid pwer cnditining system fr residential use, IEEE Trans. Energy Cnvers., vl. 1, n., pp , Jun F. Valenciaga and P. F. Pulestn, Supervisr cntrl fr a stand-alne hybrid generatin system using wind and phtvltaic energy, IEEE Trans. Energy Cnvers., vl. 0, n., pp , Jun G. Patunakis, Y. W. Li, and K. L. Shepard, A fully integrated n-chip DC DC cnversin and pwer management system, IEEE J. Slid-State Circuits, vl. 39, n. 3, pp , Mar M. Calvic, Linear regulatr design fr a lad and frequency cntrl, IEEE Trans. Pwer App. Syst., vl. PAS-91, n. 6, pp , Nv P. H. Chu, C. Park, J. Park, K. Pham, and J. Liu, B#: A battery emulatr and pwer prfiling instrument, in Prc. Int. Symp. Lw Pwer Electrn. Des., Aug. 003, pp A. Asteriadis, T. Lapuls, S. Sisksl, and M. Bafleur, A lw quiescentcurrent, lw supply-vltage linear regulatr, in Prc. 1st IEEE Instrum. Meas. Technl. Cnf., May 004, pp F. C. Yang, C. C. Chen, J. J. Chen, Y. S. Hwang, and W. T. Lee, Hysteresis-current-cntrlled buck cnverter suitable fr Li-In battery charger, in Prc. Int. Cnf. Cmmun., Circuits Syst., Jun. 006, vl. 4, pp T. J. Liang, T. Wen, K. C. Tseng, and J. F. Chen, Implementatin f a regenerative pulse charger using hybrid buck bst cnverter, in Prc. 4th IEEE Int. Cnf. Pwer Electrn. Drive Syst., Oct. 001, pp M. Milanvic, A. Rskaric, and M. Auda, Battery charger based n duble-buck and bst cnverter, in Prc. IEEE Int. Symp. Ind. Electrn., Jul. 1999, pp S. Y. Tseng, J. S. Ku, S. W. Wang, and C. T. Hsieh, Buck bst cmbined with active clamp flyback cnverter fr pv pwer system, in Prc. IEEE Pwer Electrn. Spec. Cnf., Jun. 007, pp S. V. Araúj, R. P. Trric-Bascpé, F. L. M. Antunes, and E. Mineir Sá, Stand-alne phtvltaic system using an UPS inverter and a micrcntrlled battery charger based n a bst cnverter with a 3 state-cmmutatin cell, in Prc. 3nd Annu. Cnf. IEEE Ind. Electrn. Sc., Nv. 006, pp B. P. McGrath, D. G. Hlmes, P. J. McGldrick, and A. D. McIver, Design f a sft-switched 6-kW battery charger fr tractin applicatins, IEEE Trans. Pwer Electrn., vl., n. 4, pp , Jul R. Ayyanar and N. Mhan, A nvel full-bridge DC DC cnverter fr battery charging using secndary-side cntrl cmbines sft switching ver the full lad range and lw magnetics requirement, IEEE Trans. Ind. Appl., vl. 37, n., pp , Mar./Apr Authrized licensed use limited t: Ka Yuan University. Dwnladed n May 30, 009 at 1:5 frm IEEE Xplre. Restrictins apply.

8 CHUANG et al.: IMPLEMENTATION AND ANALYSIS OF CONVERTER OPERATING ABOVE RESONANCE Y. C. Chuang and Y. L. Ke, A nvel high-efficiency battery charger with a buck zer-vltage-switching resnant cnverter, IEEE Trans. Energy Cnvers., vl., n. 4, pp , Dec R. J. King and T. A. Stuart, A nrmalized mdel fr the half-bridge series resnant cnverters, IEEE Trans. Aersp. Electrn. Syst., vl. AES-17, n., pp , Mar K. W. Sek and B. H. Kwn, A nvel single-stage half-bridge AC DC cnverter with high pwer factr, IEEE Trans. Ind. Electrn., vl. 48, n. 6, pp , Dec F. S. Hamdad and A. K. S. Bhat, Three-phase single-stage AC/DC bst integrated series resnant cnverter, IEEE Trans. Aersp. Electrn. Syst., vl. 40, n. 4, pp , Oct C. Q. Lee and K. Siri, Analysis and design f series resnant cnverter by state-plane diagram, IEEE Trans. Aersp. Electrn. Syst., vl. AES-, n. 6, pp , Nv S. J. Chiang, C. M. Liaw, J. H. Ouyang, and C. C. Chiang, Multimdule parallel series-laded resnant cnverters, IEEE Trans. Aersp. Electrn. Syst., vl. 31, n. 1, pp , Jan Ying-Chun Chuang received the B.S. degree in electrical engineering frm the Natinal Taiwan University f Science and Technlgy, Taipei, Taiwan, in 1988, the M.S. degree in electrical engineering frm Natinal Cheng Kung University, Tainan, Taiwan, in 1990, and the Ph.D. degree in electrical engineering frm Natinal Sun Yat-Sen University, Kahsiung, Taiwan, in Since August 1990, he has been with the Department f Electrical Engineering, Kun Shan University, Tainan, where he is currently an Assciate Prfessr. His research interests include pwer electrnics and pwer systems. Hung-Shiang Chuang was brn in Kahsiung, Taiwan, in He received the B.S., M.S., and Ph.D. degrees in mechanical engineering frm Natinal Chen-Kung University, Tainan, Taiwan, in 1987, 1989, and 001, respectively. He is currently an Assciate Prfessr with the Department f Electrical Engineering, Ka Yuan University, Kahsiung, Taiwan. His research interests include mtr cntrl, drive technlgies, and autmatic ptic inspectin. Hung-Kun Chen was brn in Kahsiung, Taiwan, in 198. He received the B.S. degree in electrnic engineering frm Ka Yuan University, Kahsiung, in 005, and the M.S. degree frm Kun Shan University, Tainan, Taiwan, in 007. Since 007, he has been an Electrical Engineer with the Department f Electrical Engineering, Sunnwealth Electric Machine Industry Cmpany, Kahsiung. His research interests are in battery chargers and switching pwer supplies. Yu-Lung Ke (M 98 SM 06) was brn in Kahsiung City, Taiwan, n July 13, He received the B.S. degree in cntrl engineering frm the Natinal Chia Tung University, Hsinchu, Taiwan, in 1988, the M.S. degree in electrical engineering frm the Natinal Taiwan University, Taipei, Taiwan, in 1991, and the Ph.D. degree in electrical engineering frm the Natinal Sun Yat-Sen University, Kahsiung, Taiwan, in 001. Since August 1991, he has been with the Department f Electrical Engineering, Kun Shan University, Tainan, Taiwan, where he is currently a Full Prfessr in the Department and the Institute f Electrical Engineering. He served as a Reviewer fr the Institutin f Engineering and Technlgy (IET) Pwer Electrnics, theiet Generatin, Transmissin and Distributin, the Prceedings f Institute f Electrical Engineers n Generatin, Transmissin and Distributin, the Internatinal Jurnal f Electrical Pwer and Energy Systems,andtheInternatinal Jurnal f Pwer and Energy Systems. His research interests include pwer systems, energy technlgy, cntrl engineering, and pwer electrnics. Dr. Ke is a Registered Prfessinal Engineer in Taiwan. Since 00, he has served as a Reviewer fr the IEEE TRANSACTIONS ON POWER ELECTRONICS, IEEE TRANSACTIONS ON POWER SYSTEMS, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, and IEEE TRANSACTIONS ON POWER DELIVERY. Hewas als a Reviewer fr the 009 IEEE Energy Cnversin Cngress and Expsitin and the 39th IEEE Pwer Electrnics Specialists Cnference. Authrized licensed use limited t: Ka Yuan University. Dwnladed n May 30, 009 at 1:5 frm IEEE Xplre. Restrictins apply.