Power Density and Efficiency Optimization of Resonant and Phase-Shift Telecom DC-DC Converters

Transcription

1 Power Density nd Effiieny Optimiztion of Resonnt nd PhseShift Teleom DCDC Converters U. Bdstuener, J. Biel nd J. W. Kolr Power Eletroni Systems Lortory, ETH Zurih ETHZentrum, ETL H12, Physikstrsse 3 CH892 Zurih, Switzerlnd Emil: dstuener@lem.ee.ethz.h This mteril is posted here with permission of the IEEE. Suh permission of the IEEE does not in ny wy imply IEEE endorsement of ny of ETH Zürih s produts or servies. Internl or personl use of this mteril is permitted. However, permission to reprint/repulish this mteril for dvertising or promotionl purposes or for reting new olletive works for resle or redistriution must e otined from the IEEE y writing to puspermission@ieee.org. By hoosing to view this doument you gree to ll provisions of the opyright lws proteting it.

2 Power Density nd Effiieny Optimiztion of Resonnt nd PhseShift Teleom DCDC Converters U. Bdstuener, J. Biel nd J. W. Kolr Power Eletroni Systems Lortory, ETH Zurih ETHZentrum, ETL H12, Physikstrsse 3 CH892 Zurih, Switzerlnd Emil: dstuener@lem.ee.ethz.h Astrt Power density nd effiieny re one of the mjor driving fores in the development of new power supplies for teleommunition nd informtion industry. The phseshift PWM nd the seriesprllel resonnt DCDC onverter re promising topologies tht n meet these demnds t high power rtes. Bsed on onventionl riteri suh s the numer of semiondutors/pssive omponents or voltge/urrent stress it is not possile to identify the topology tht offers higher power density or effiieny. Therefore, n optimiztion proedure hs een developed, whih lultes the optiml onverter prmeters (e.g. swithing frequeny or trnsformer design) with respet to the mximl power density nd/or effiieny. This proedure is sed on detiled nlytil models for the onverter, semiondutor losses, HF losses in the mgneti omponents s well therml nd geometril models of the trnsformer. With the proedure 5 kw seriesprllel resonnt onverter nd phse shift onverter with pitive output nd with urrent douler hve een optimized. With the lulted prmeters resonnt onverter prototype hs een onstruted nd experimentl results re presented. I. INTRODUCTION Over the lst dedes, mjor effort in the informtion nd teleommunition industry hs een inresing the power density of the deployed power supplies in order to meet the design requirements onerning mximum weight, limited spe nd prodution osts [1]. The inresing density hs een minly enled y the ontinuous development of high performne swithing devies whih llow higher swithing frequeny t reltively low swithing losses, wht leds to redued volume of the pssive omponents. Besides the power density, system effiieny is mjor driving fore due to the ontinul inrese of energy onsumption nd osts. Therefore, the development fouses now on high effiieny power supplies, whih enle ost nd ooling effort redution. Swith mode power supplies pplied in teleommunition systems nd dt enters typilly onsist of n ACDC retifier with power ftor orretion (PFC) s input stge nd Tle I: Typil speifitions of IT DCDC onverter. Input voltge V IN 4 V Output voltge V OUT V Output power P OUT 5 kw Output ripple voltge V ripple 3 mv pp Mx. mient temperture T m 45 C Retifier 4 MOSFETs Gte Drives Digitl Control Bord Fn Series Cpitor C s Trnsformer with Integrted Series Indutne L s Prototype: Height: 1 U = 1.75 in 44 mm, volume:.49 liter, power density: 167 W/in 3 = 1.2 kw/liter VIN C IN s11 A IP s12 B s21 s 22 C S VAB L S NP N S C P NS C P ) LCfilter L OUT COUT COUT ) Cfilter Shemti: ) LCfilter nd ) pitive filter s output stge Figure 1: Prototype nd shemti of seriesprllel resonnt DCDC onverter, 5 kw, 4 V/ V. DCDC onverter s output stge, whih steps the DC link voltge down to the required output voltge of 48 V to 54 V. There, usully trnsformers, enling lrge voltge trnsfer rtio, re pplied for glvni isoltion (e.g. [2],[3]). The typil speifitions for IT DCDC onverters re given in tle I. In the literture severl topologies for the retifier nd DCDC onverter hve een proposed (e.g. [4][11]). A omprison of these topologies sed on riteri like stress of the semiondutors, numer of swithes or IS N S NS IS IR1 IR2 IR1 IR2 IOUT IOUT VOUT V OUT /8/$ IEEE 311

3 ZVS/ZCS ondition only llows to redue the numer of topologies to few promising ones. For more detiled omprison identifying the most suitle topology, n optimiztion of eh topology with respet to the onsidered omprison riteri, power density nd effiieny, is required. Therefore, omprison of different DCDC onverters topologies sed on n optimiztion proedure with omprehensive nlytil models is presented in this pper. The most suitle topologies for high power teleom onverters re the seriesprllel resonnt onverter (shemti nd the onstruted hrdwre sed on the optimiztion proedure re shown in Fig. 1) nd the phseshift PWM onverter (f. Fig. 2), whih oth llow softswithing. For these two onverters different output stges (LCfilter, Cfilter with mid point onnetion nd urrent douler) re possile nd hve een investigted [12]. A short survey on pplile topologies nd n evlution, sed on the mentioned riteri with respet to the hievle power density nd effiieny, is given in in Setion II. There, lso the opertion of the phseshift nd the seriesprllel resonnt onverter inluding the digitl ontrol using stte mhine is shortly explined. For the topology omprison omprehensive optimiztion proedure is required, whih is presented in Setion III with the orresponding different nlytil models for the onverters suh s the HF trnsformer losses nd the temperture distriution. With the presented optimiztion proedure the two topologies hve een optimized, one for power density nd one for mximum effiieny. The orresponding results of the optimiztion nd omprison of oth onverter topologies re disussed in Setion IV. In the sme setion vlidtion of the resulting optimized prmeters sed on iruit simultion is given. For vlidting the results prototype nd mesurement results of n optimized seriesprllel resonnt onverter re presented in Setion V. There, lso the design of phseshift onverter with urrent douler nd the omprison etween opper nd luminum het sinks is given. II. CONVERTER TOPOLOGIES FOR IT APPLICATIONS In the re of low power onverters often flyk nd single swith forwrd onverters re pplied. These topologies re not suitle if high output power with high effiieny is required. Enhned nd/or other topologies proposed for teleom supplies re, for exmple, the doule interleved forwrd onverter [4], [13], the symmetril hlf ridge [5] nd multiresonnt topologies [7]. However, these topologies do not fit the requirements onerning effiieny nd high power density in the sme wy s full ridge topologies, operting with soft swithing, due to the mount of semiondutors nd pssive omponents nd/or the utiliztion of the duty yle in hlf rides whih results in lrger trnsformers. In ddition, the swithing nd ondution losses in symmetril hlf ridges inrese nd the effiieny dereses due to the symmetril urrent wveforms t high input voltges [6]. As lredy mentioned in setion I, the seriesprllel resonnt (f. Fig. 1 ottom) nd the phseshift PWM fullridge DCDC onverter (f. Fig. 2) re well pplile for the onsidered teleom pplition. Both onverters opertes VIN C IN s11 s 12 A s 21 I P B s22 L σ N P ) Current douler N S NS 2N S C OUT ) Cfilter Figure 2: Shemti of phseshift DCDC onverter with ) urrent douler or ) entertpped trnsformer with LCfilter. with softswithing nd enle high effiieny t higher output power levels. In ddition, fullridge onverters etter utilize the trnsformer due to the ipolr flux swing. Therefore, smller trnsformer size nd weight n e hieved. A. PhseShift PWM DCDC Converter When operting onventionl PWM full ridge t high power nd high frequeny, the onverter performne will e redued y the swithing losses due to the iruit prsitis. A speillyoperting mode of the PWM full ridge, llows ll swithing devies (f. Fig. 2) to operte under zero voltge (ZVS) ondition (e.g. in [2], [11]). There, the prsitis of the iruit re dvntgeously used to hieve the softswithing ondition. In Fig. 2 two possile output stges re shown: mid point onnetion with Cfilter (CTC) nd the urrent douler (). Both topologies enle ompt onstrution with high effiieny nd will e onsidered in the optimiztion. In Fig. 3 the ontrol sheme nd the priniple voltge/urrent wveforms of the phseshifted PWM onverter re given. There, the power flow is ontrolled y the phseshift etween the two legs, whih lso determines the duty yle of the onverter. The swithing of ll four IGBTs/MOSFETs is performed under ZVS ondition y using the energy stored in the lekge indutne (L σ, f. Fig. 2), in order to hrge/dishrge the prsiti output pitnes of oth swithes in the swithing leg. Further detils n e found in literture mentioned ove. B. SeriesPrllel Resonnt DCDC Converter The seriesprllel resonnt onverter is omintion of series nd prllel resonnt DCDC onverter, s shown in Fig. 1. With proper hoie of the resonnt tnk omponents vlues (C S, L S nd C P ), the seriesprllel resonnt onverter omines the dvntges of the series resonnt onverter: Series pitor C S loks the DC voltge, thus voiding the trnsformers sturtion The prtil lod effiieny is high due to the derese in devie urrents with derese in lod nd the dvntges of the prllel resonnt onverter: Controlled opertion t light lod L S1 C OUT V OUT LS2 I OUT I OUT VOUT 312

4 Tle II: Constrints used for the optimiztion proedure (CSP I = Cooling System Performne Index f. [17]). s 11 s 21 s 12 s 22 V IN s11 s12 I P A B s21 s 22 Leg A Leg B s11 s21 s12 s22 I P s11 s21 s12 s22 I P s11 s21 s 12 s 22 I P t t t Mx. Width 1 U = 1.75 in 44 mm Core Mteril N87 (EPCOS, T mx 115 C) MOSFETs APT5M75 (Mirosemi, former APT) Retifier Diodes APT1S2 (Mirosemi, former APT) Cpitors C S nd C P 3.9 nf, 8 V, COG (NOVACAP) CSP I 23 Mx. Juntion Temp. T j,mx 14 C SPR V IN CTC Figure 3: Swithing sttes nd urrent wveforms for phseshift onverter with pitive output filter nd urrent douler s well s for the seriesprllel resonnt DCDC onverter with pitive output filter. while most of the disdvntges of the two onverters re eliminted (e.g. [6], [9], [14]. Furthermore, the onverter is nturlly short iruit proof. For ompt design, entertpped trnsformer with retifier s output stge results in lower volume if high output urrents re required. As presented in [8], the pitive output filter (f. Fig. 1 ) results in smller volume thn the LCfilter for high output urrents. Therefore, the LCfilter is not onsidered in the following. As the phseshifted onverter, the seriesprllel resonnt onverter provides soft swithing of ll 4 swithes. By ontrolling the zerorossing of the resonnt urrent I P it is possile to hieve zerovoltge swithing in one leg nd zerourrent swithing (ZCS) in the other one. The opertion priniple of the swithes is similr to the phseshifted onverter s shown in Fig. 3. Due to the filtering tion of the resonnt iruit the primry urrent I P is pproximtely sinusoidl, whih hs the enefit of etter EMI performne. As it n e seen in the shemtis (Fig. 1) nd Fig. 2) nd the ontrol sheme (f. Fig. 3), the phseshift nd the resonnt onverter re very similr nd show lmost the sme performne nd similr effiieny (e.g. [3]). Thus, onventionl riteri re not suffiient to identify the most suitle espeilly in respet to miniml volume, lowest ost or highest effiieny. By mens of optimizing the three onverter topologies for one or even more riteri like power density nd/or effiieny sed on detiled models, profound omprison sed on the optimiztion is possile. This optimiztion proedure nd the ssoited models desried in the following setion. V IN III. OPTIMIZATION PROCEDURE For the omprison of the different topologies, the omponent vlues must e hosen, so tht the power density nd/or the effiieny eomes mximl. Sine the volume of the single omponents, whih re minly limited y the respetive mximum opertion temperture, interdependent to some extent on eh other, the optimiztion of the overll volume is quite diffiult tsk with mny degrees of freedom. Therefore, n utomti optimiztion proedure is pplied for determining the optiml omponent vlues of the teleom supply. The optimiztion proedure is minly sed on 4 models: An nlytil onverter model, sed on the extended fundmentl nlysis (seriesprllel resonnt onverter, [8], [15]) nd/or time domin nlysis (phseshift onverter, [16]), respetively Equtions for the semiondutor swithing nd ondution losses, sed on mesurements Model for the volumes of the resonnt tnk pitors, inluding dieletri losses A model of the losses nd the temperture distriution in the trnsformer with integrted series indutne for optimizing the trnsformer geometry. In the following the optimiztion proedure will e explined riefly. There, lso referenes where the models re explined in detil re listed. The strting point of the proedure is the initiliztion of the design prmeters like input voltge, output power, temperture limits nd mteril hrteristis s presented prtilly in tle I nd tle II. These prmeters s well s strting vlues like C S, C P, L S, L Out1,2 nd the numer of turns of the trnsformer (N P nd N S ) must e speified y the user. With the vlues for the mgneti omponents nd the turns numer the model for the mgneti omponents is prmeterized. There, relutne model of the trnsformer with integrted indutne in omintion with the nlytil onverter model, whih desries the opertion of the onverter nd the flux distriution in the ore is used in se of the resonnt onverter [8], [15]. The models for the phseshift onverters re sed on nlytil expression for the flux distriution nd the optiml winding geometry [18]. With the frequeny, duty yle, urrents nd voltges resulting from the nlytil onverter model [8], [15], the vlue nd volumes of resonnt tnk pitors s well s the swithing nd ondution losses in the MOSFETs nd retifier diodes re determined, sed on the models presented in [8]. These losses, the mient temperture nd the mximum juntion tempertures of the semiondutor devies re used for lu 313

5 lting the volume of the semiondutor het sink inluding the fn sed on the CSP I (Cooling System Performne Index) [17]: CSPI [ ] W 1 Kdm = [ 3 R K ] (1) th,s W V olcs [liter] with the therml resistne R th,s of the het sink nd the volume of the het sink inluding fn V ol CS. The volume nd the shpe of the trnsformer/indutor ore nd the two windings is determined in seond, inner optimiztion proedure, sed on trnsformer model s presented in [8], [15]. There, the volume of the trnsformer/indutor is minimized while keeping the tempertures elow the llowed limits. The temperture distriution in the ore/winding is lulted with therml model nd the ore nd the winding losses (inluding HFlosses). The resulting minimized trnsformer/indutor volume re pssed to the glol optimiztion lgorithm together with the volumes of the het sink nd pitors. Bsed on the result the free prmeter vlues re systemtilly vried until miniml system volume nd/or mximl effiieny is otined. More detiled informtion out the optimiztion nd the orresponding models n e found in [1], [8], [12], [15] IV. OPTIMIZATION AND SIMULATION RESULTS Bsed on the optimiztion proedure presented in the preeding setion the three onsidered topologies phse shift with pitive output filter nd urrent douler s well s the resonnt onverter with pitive output filter hve een optimized for the dt given in tle I nd II. The resulting operting prmeters re presented in tle III. The highest power density is hieved with the seriesprllel resonnt onverter: 19.1 kw/ltr. (313 W/in 3 ) if only the net omponent volumes, the PCBs nd housings re onsidered. The finl system volume strongly depends on the 3D design of the onverter. For the prototype shown in Fig. 1 the power density resulting of the optimiztion ws 15 kw/ltr., whih is lower thn the results presented here sine other omponents hve een used during the optimiztion of this onverter. The finl ssemled onverter hd 1 kw/ltr. (164 W/in 3 ), wht results in sling ftor of 2/3 etween lulted nd finl power density. The phseshift onverters hieve power densities of 14.7 kw/ltr. (with urrent douler) nd 11.7 kw/ltr. (with pitive output filter). If the sling ftor is ssumed s for the ssemled resonnt prototype, the totl system power density of the presented resonnt onverter is 12.7 kw/ltr. (28 W/in 3 ), for the phseshift onverter with urrent douler 7.8 kw/ltr.(128 W/in 3 ) nd with pitive output filter 1 kw/ltr. (164 W/in 3 ). At the opertion point, optimized for mximum power density, the effiieny of the resonnt onverter is 96.2 %, for the phse shift onverter with urrent douler 94.8 % nd with pitive output 95. % respetively. However, n optimum effiieny results in different swithing frequenies for ll three onverters, s shown in Fig. 4. For the resonnt onverter the effiieny inreses to 96.3 % with n inresed swithing frequeny ( 22 khz), euse there, the losses of the trnsformer re lower. The phseshift onverter hieves the mximum effiieny when operting with 1 khz minly driven y the deresing losses of the semiondutors whih drstilly inrese ove 3 khz. A similr ehvior shows the phse shift onverter with the pitive output filter. There, the losses eomes minimum t the lowest onsidered frequeny of 25 khz. However, with the inresing effiieny of the phse shift onverter t lower swithing frequenies the volume of the mgneti omponents(trnsformer nd indutor) inreses signifintly, whih results in muh smller power density s shown in Fig. 4. The dimensions of the ferrite ores (EPCOS N87) re lso inluded in tle III nd illustrted in Fig. 5. In the optimiztion of the mgneti devies nd foil windings, where only one turn per lyer is relized, hve een ssumed. Moreover, the integrtion of the required series/lekge indutne for the three onverters in the trnsformer is onsidered in the Tle III: Resulting opertion point nd speifitions of the optimized 5 kw teleom supplies. There, the losses in the two indutors of the re W, the AC flux density is 77 mt nd the geometry f. Fig. 5 is: =1 mm =21 mm =7 mm d=12. (In rkets: simulted vlues inluding more prsiti elements thn onsidered in the nlyti model if differing from the lulted results.) Phse Shift Resonnt CTC SPRC Power Density 11.7 kw/ltr kw/ltr kw/ltr. Operting Point Frequeny 2 khz 1 khz 135(13) khz Duty Cyle.81(.86).82(.88).78(.83) Effiieny 94.8 % 95. % 96.2 % Trnsformer Pri. Wind. Losses 6. W 13. W 5.7 W Se. Wind. Losses 1. W 11.6 W 15.3 W Core Losses 13.8 W 23.7 W 23.5 W Turns Rtio 11:4 11:2:2 14:2:2 Winding Temp. 125 C 124 C 125 C Core Temp. 17 C 115 C 115 C Flux Density 175 mt 24 mt 3 mt Geometry (f. Fig.5) Mid Leg 13. mm 15. mm 14. mm Height 19.3 mm 21. mm 12.2 mm Window Width 9.4 mm 7. mm 7. mm Window Height d 15.1 mm 29.4 mm 31. mm Lekge Leg e 7.4 mm 1.6 mm MOSFETs (f. Fig. 6) Turnoff urrent 21. A 17.3 A A I off,a (21.2 A) (17.7 A) ( A) Turnoff urrent 21.9 A 32.5 A 15.6 A I off,b (22.2 A) (31.9 A) (15.4 A) P V,swithing 31.2 W 17.8 W <5 W P V,ondution 93.7 W 96.8 W 64. W L nd C Ser. Ind. L S 2 µh 12.4 µh 26.5µH Out. Ind. L OUT 6.7 µh Ser. Cp. C S 98.5 nf Pr. Cp. C P 26. nf Out. Cp. C OUT 11 µf 438µF 254µF 314

6 Power density [kw/ltr.] CTC SPRC Frequeny f [khz] Effiieny [%] SPRC CTC Frequeny f [khz] Figure 4: Power density nd effiieny of the seriesprllel resonnt onverter with pitive output (SPRC), phseshift onverter with urrent douler () nd pitive output (CTC) in dependeny of the swithing frequeny. optimiztion. There, lso the flux distriution/sturtion nd HFlosses s skin nd proximityeffet losses re onsidered. This results, e.g. in n optiml foil thikness of 65 µm for the primry winding nd 15 µm for the seondry winding. d L S1 d /2 SPRC L S2 /2 d d /2 e d Distriuted Air Gps e CTC Figure 5: Dimensions of the trnsformer ores nd the indutors (for the ) resulting from the optimiztion proedure for the seriesprllel resonnt onverter with pitive output (SPRC), phseshift onverter with urrent douler () nd pitive output (CTC). A. Simultion Results With the system prmeters resulting from the optimiztion proedure (f. tle III) simultion models of the onverters hve een developed in Simplorer (Ansoft). The hrteristi simulted wveforms re shown in Fig. 6. The orresponding vlues resulting from the simultion re given in rkets in tle III, where good orrespondene etween nlytil model nd simultion n e seen. The slight differenes re used y the ft, tht in the simultion more prsiti elements re onsidered. Bsed on the simultion results, whih onfirm the nlytil optimiztion, prototypes of the onverters n e designed. Some detils of these prototypes will e presented in the following setion. V. PROTOTYPES AND MEASUREMENT RESULTS Bsed on the optimiztion results prototype of the seriesprllel resonnt onverter hs een onstruted (f. Fig. 1 nd 7). CTC SPRC I Off,B I 4 Off,A I Off,B Vse V se I Off,A 1.I P I Off,B 4 IOff,A V CP 1.I P 1.I P Time t in [µse] Figure 6: Simulted urves of, I P, V se nd V Cp (f. Fig. 1) nd Fig. 2) for the three presented onverter with the prmeters resulting from the optimiztion proedure. This 5 kw prototype hs volume of.49 ltr., resulting in power density of 167 W/in 3 (1.2 kw/ltr.). With the new omponents utilized in the presented optimiztion this power density ould e inresed to pproximtely 12 kw/ltr. Besides the optimiztion of the semiondutor het sink, the integrtion of the series indutne L S nd the ooling of the mgneti omponent is very importnt. The tehnil reliztion of this trnsformer is illustrted in Fig. 8. The lekge indutne is generted in the top leg y the insertion of distriuted ir gps. Sine the Hfield would result in eddyurrents in the het trnsfer omponent (HTC) of the primry winding/lekge leg, slots re milled into the HTC in the re over the ir gps. Sine the primry winding is enlosing the lekge flux pth the rdited Hfield is reltively low with this design. Output Connetors Trnsformer Output Voltge/Current Mesurement Bord Output Cpitne C OUT = 5µF Prllel Cpitne C P = 12nF Retifier Diodes Isolted Figure 7: Bk view of the resonnt DCDC onverter prototype. 315

7 Trnsformer Tle IV: Comprison of het sink mterils: luminum. opper nd Primry Winding Copper design Aluminum design Het sink / HTC only 177 m m 3 Totl volume (quder) 499 m m 3 Power density 1 kw/ltr kw/ltr. Air Gps Core N87 Retifier Diodes Het Trnsfer Component (HTC) Seundry Winding Figure 8: Setionl drwing of the trnsformer of the resonnt onverter with integrted series indutne. Trnsformers Totl Design SeriesPrllel Resonnt DCDC Converter In Fig. 9 first mesurement results for the resonnt onverter re shown. There, nerly sinusoidl wveform of the resonnt urrent t the lredy mximum designted input voltge of 4 V nd the output power of 1.25 kw ould e seen. voltge [V] I P time t [μs] Figure 9: Mesurement results of the resonnt onverter prototype (f. Fig. 1)) V IN = 4 V, I IN = 3.4 A, V = 44.3 V, I = 28.2 A, P O = 1.25 kw. A. Copper vs. Aluminum s Mterils In order to otin the upper limit of the power density, opper hs een ssumed for the het sink nd the ooling system of the trnsformer during the optimiztion. Due to inresing rw mteril pries the question rises, wht is the limit for the power density if luminum (λ Al = 23 W /m K) would e used insted of opper (λ Cu = 39 W /m K). For determining the impt of the mteril esides the prototype sed on opper lso prototype with luminum hs een designed y numeril CFD simultion (ICEPACK). There the temperture distriution hs een kept onstnt. The different therml ondutivity hs strong influene to the optiml thikness of the fins nd the rtio in respet to the ir urrent I P [A] MOSFETs Fn Het Trnsfer Component (HTC) Core with Distriuted Gps (Lekge Indutne) Figure 1: Het sink omponents for the seriesprllel resonnt onverter, designed for luminum. spes [17]. By optimizing the design of the fins, the impt of the hlved therml ondutivity n e lerly redued. The resulting volumes re presented in tle IV. The volume of the pure het sink omponents (het trnsfer omponents (HTC), het sink for diodes, MOSFETs nd trnsformer f. Fig. 1) inreses y 9 % if opper is repled y luminum. However, the totl design volume inreses only y 3.8 %, sine. Consequently. the power density dereses y the sme ftor to 9.65 kw/ltr. Therefore, with proper design of the irool het sink the overll volume is only slightly influened y the het sink mteril. B. Integrted Mgnetis for the Current Douler The optiml volume of the urrent douler trnsformer inluding ore, het trnsfer omponent (HTC), windings nd het sink, is pproximtely 9 m 3. Together with the two output indutors, the totl volume of the mgneti omponents is pproximtely 23 m 3 when using very ompt ommerilly ville indutors nd not onsidering the spe needed for onneting nd mounting. By integrting the output indutors on the sme ore/winding s the trnsformer s presented e.g. in [19], [2] the power density n e further inresed. With stndrd E65/32/27 ferrite ore from EPCOS the volume dereses y 6.5 % to 215 m 3. With ustom ore redution of 12 % for the volume nd lso redution of the losses in the mgneti devies ould e hieved. In Fig. 11 design of the phseshift onverter with urrent douler sed on luminum is shown. There, power density of pproximtely 9.75 kw/ltr. ould e hieved. This vlue is higher thn the predited vlue of 7.8 kw/ltr. due to the integrted mgnetis nd ove 316

8 Trnsformer MOSFETs Gte Drives Primry nd Seundry Windings Retifier Diodes Digitl Control Bord Figure 11: Design of phse shift onverter with urrent douler nd integrted mgnetis. s re mde of luminum. ll due to the more ompt design ompred to the resonnt onverter, so tht the sling ftor of 2/3 is inresed. VI. CONCLUSION In this pper, n optimiztion proedure is used for mximizing the power density nd the effiieny of phseshift DCDC onverter with pitive output filter (CTC) nd with urrent douler () s well s seriesprllel resonnt with pitive output filter in order to identify the most suitle topology for 5 kw teleom pplitions. The nlytil models of the optimiztion proedure inlude eletril models for the onverter, models of the HF losses in the mgneti omponents, therml models for the trnsformer nd volume models for the het sinks/resonnt pitors. There, mximl 12 kw/ltr.,196 W/in 3 (19 kw/ltr. pure omponent volume) re otined for the seriesprllel resonnt onverter (SPR). The optiml operting frequeny with respet to the power density is pproximtely 135 khz. For the phse shift onverter 1 kw/ltr. (164 W/in 3 ) result for pitive output filter (CTC) nd 7.8 kw/ltr. (128 W/in 3 ) for urrent douler (). Agin, the optiml operting frequenies re reltively low pproximtely 1 khz for the CTC nd 2 khz for the. There, the effiienies re 96.2 % for the SPR, 95 % for the CTC nd 94.8 % for the. These vlues slightly improve (.8%) if the onverter is optimized for effiieny, ut there the power density dereses signifintly. By using integrted mgnetis for the volume redution of 12 % for the mgneti omponents is possile. In se luminum is used insted of opper for the het sink nd the ooling system of the trnsformer the system volume inreses y pproximtely 4 %. For vlidting the nlytil models used in the optimiztion 5 kw seriesprllel resonnt DCDC onverter hs een onstruted nd detiled simultions hve een performed. REFERENCES [1] J. W. Kolr, U. Drofenik, J. Biel, M. L. Heldwein, H. 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