Three-Phase PWM Power Conversion The Route to Ultra High Power Density and Efficiency

Transcription

1 Three-Phase PWM Power onverson The Rote to Ultra Hgh Power Densty and Effcency J. W. Kolar, J. Mnböck, and M. amann Swss Federal Insttte of Technology (ETH) Zrch Power Electronc Systems aboratory ETH Zentrm / ET H22 Physkstr. 3, H-892 Zrch/Swtzerland kolar@lem.ee.ethz.ch Abstract. A revew of three-phase PWM converter topologes whch do show a low complexty / hgh relablty and hgh effcency and power densty and are therefore of man nterest for a ftre ndstral applcaton s presented. A three-swtch/level boost-type PWM rectfer (VIENNA Rectfer), a bck+boost-type PWM rectfer wth wde otpt voltage range and the A/A Sparse Matrx onverter concept are dscssed n detal and topcs to be treated n the corse of frther research are dentfed. Fnally, t s shown how the aspects beng relevant for the realzaton of hghly compact converter systems cold be ntegrated nto edcaton n the feld.. Introdcton De to gdelnes, recommendatons and reglatons concernng a lmtaton of the harmonc nflence of power electronc systems on the mans and based on the reqrement of operaton n a wde npt voltage range nmeros three-phase PWM converter topologes wth low effects on the mans have been proposed []. After the clarfcaton of the basc operatng behavor and the optmzaton of the modlaton and control scheme of each converter topology crrent research s amng for an ncrease of the power densty and effcency nder applcaton of novel power semcondctor technologes and materals (S), and novel nterconnecton and coolng concepts. There, the focs s on topologes whch do show a low complexty and/or hgh relablty, a low stress on the power semcondctors and a low volme of the passve power components. Therefore, n ths paper a revew of three-phase PWM converter topologes whch are of man nterest for a ftre ndstral applcaton,.e. the VIENNA Rectfer (cf. Secton 2), the three-phase bck+boost rectfer (cf. Secton 3) and the Sparse Matrx onverter (cf. Secton 4) wll be gven and topcs for frther research wll be dentfed. For the realzaton of ltra-compact power electronc systems a well fonded knowledge n crct theory and control engneerng and a sond nderstandng of the bascs of the thermal and electromagnetc behavor s a strct reqrement. Therefore, n conclson t s dscssed brefly how these areas cold be ntegrated nto modern edcaton n order to ensre a frther dynamc development of the feld. 2. Three-Swtch/evel oost-type PWM Rectfer An ndrectonal three-phase PWM rectfer system wth ohmc fndamental mans behavor and controlled otpt voltage can be realzed n the form of a star-connecton of sngle-phase A/D converters (Y-Rectfer, cf. Fg.) or, as proposed n [2] n the form of the VIENNA Rectfer (cf. Fg.). As compared to a conventonal bdrectonal (two-level) PWM A/D converter (cf. Fg.2) both crct topologes do show a three-level characterstc of the brdge legs and accordngly a sgnfcantly lower voltage stress on the power semcondctors. Frthermore, for gven rms vale of the rpple of the npt crrent and gven swtchng freqency the three-level characterstc does allow a redcton of the ndctance of the npt ndctors resltng n a hgh system power densty. Fg.: Realzaton of a threephase ndrectonal boosttype PWM rectfer system by star-connecton of sngle-phase PWM rectfer systems or n the form of the VIENNA Rectfer. The man advantage of the system shown n Fg. as compared to Fg. s a sngle otpt voltage beng common to all brdge legs. Ths does allow to mnmze the realzaton effort n case a mans voltage hold-p or a hgh-freqency solaton of the otpt voltage has to be provded. Accordngly, the system s appled n the ndstry n hgh-power telecommncatons power spply modles, process technology power spples and A drves wthot reqrement of feedng brakng energy back nto the mans. Fg.2: Strctre of the power crct of a conventonal voltage D lnk PWM converter (shown for applcaton as PWM rectfer). Frther topologes for the realzaton of a brdge leg of the VIENNA Rectfer are shown n Fg.3. As Fg.3 clearly shows, the voltage formaton, at the npt of a phase leg s not only dependent on the swtchng state of the power transstor S bt also on the sgn of correspondng phase crrent N,. The space vectors of the phase voltages U, whch can be formed for N,R >, N,S, N,T < are depcted n Fg.4.

2 Fg.3: rdge leg topologes of the VIENNA Rectfer alternatve to Fg.. As for the realzaton shown n Fg., for (cf. [3]) the voltage stress on all power semcondctors s defned by half the otpt voltage. For and (c) the blockng voltage of the dodes D F+, D F s determned by the total otpt voltage; accordngly a seres connecton of two dodes wth lower blockng capablty and/or lower reverse recovery tme shold be employed. Fg.4: Space vectors of the VIENNA Rectfer avalable for the formaton of the npt voltage. As for conventonal three-level PWM converters the redndant swtchng states (cf. e.g. U,() and U,() n Fg.4) do allow a balancng of the partal otpt voltages + and. Wth respect to a contnaton of the operaton n the case of a falre of a mans phase the npt crrent control does refer to phase qanttes nstead of employng space vector calcls as known from the control of three-phase A machnes. The cascaded control strctre,.e. the oter otpt voltage control loop and the nderlyng mans crrent control, s shown n Fg.5. mltpler-free phase crrent control [4] whch n contrast to conventonal average crrent mode control does not rely on a precontrol of the mans voltage. A fll tlzaton of the otpt voltage for npt crrent control s acheved by extendng the measred actal phase crrents N, by a tranglar-shaped zero-seqence sgnal,m wth three tmes the mans freqency. The balancng of the partal otpt voltages s realzed by shftng the modlatng sgnals by a postve or negatve offset. As a postve and a negatve tranglar carrer sgnal, D+ and D s employed, the dependency of the voltage formaton on the sgn of the phase crrents can be consdered by an AND gate combnng the swtchng sgnals s +, and s, n each phase. The practcal realzaton of a wde npt voltage range (U N,l-l =32 53V rms ) 2.5kW / 8V D otpt VIENNA Rectfer employng oolmos power transstors and operatng at f P =38kHz n a brdge leg topology accordng to Fg.3 s depcted n Fg.6. There, n each phase the dode D F+ s replaced by a thyrstor whch does short-crct the correspondng pre-chargng resstor after startp. The nt shows a heght of 2-U; n combnaton wth a footprnt of 25x6mm 2 ths reslts n a power densty of ρ=3.5kw/dm 3. Fg.6: Prototype of the VIENNA Rectfer. The control board s shown n front of the power crct, the axlary power spply s shown on the left hand sde. For the otpt voltage control and system management (start-p, falre handlng etc.) a low-cost mcrocontroller s employed. Fnctons reqrng a hgh bandwdth, e.g. the phase crrent control are realzed n analog technqe. Reslts of an expermental analyss of the prototype shown n Fg.6 are depcted n Fg.7 and Fg.8. N,R ' N,R D+ N,R N,R,m D - s R s R Fg.5: ontrol of the otpt voltage of the VIENNA Rectfer wth nderlyng mans phase crrent control [4]. The otpt voltage controller F(s) shows a non-lnear gan n dependency on the control error and does defne the reference vale * of the crrent chargng the otpt capactors and/or the reference vale p* of the npt power, where a load crrent precontrol s consdered. Under consderaton of the actal mans voltage condton p* s translated nto a condctance reference vale g* to be represented at the npt of each phase. y lmtaton of g* the phase crrents are lmted n ampltde accordng to the dmensonng of the system, the condctance g* lm does drectly defne the ampltde Î D of the tranglar carrer sgnal D of the Fg.7: Tme behavor of a mans phase voltage N,R (V/dv) and of the correspondng npt crrent N,R (5A/dv) recorded n peak detecton and hgh resolton mode and modlatng npt crrent N,R (cf. Fg.5), tranglar carrer sgnals D+ and D and swtchng sgnal s R of phase R (nstantaneos and local average vale). Operatng parameters: U N,l-l =4V rms, U O =675V, P O =5.kW. The mans phase crrents are controlled proportonal to the correspondng phase voltages, accordngly the dstorton of the mans crrent of THD I 4% s manly cased by low-freqency harmoncs of the mans voltage whch shows a total harmonc dstorton of THD V =2.7%. One has to pont ot the hgh system effcency of η 98% at rated mans voltage. For hgh-freqency solaton of the rectfer otpt voltage ths does allow to acheve an overall effcency of η g 93% despte the two-stage energy

3 converson. In contrast, sngle-stage PWM rectfer systems wth ntegrated hgh freqency solaton [5] are characterzed by an effcency of η g 9% de to the reqred hgher blockng capablty of the power semcondctors and/or the hgher trn-of voltage casng sgnfcantly hgher swtchng losses. THD I 24% 2% 6% 2% 8% 4% η, λ % 99% 98% 97% 96% 95% % 94% THD I η λ P O / W P / W oolmos Freewheelng dodes Mans SRs / dodes Inpt chokes Otpt capactors Axlary power Addtonal power 32V 4V 48V Fg.8: Dependency of the THD I of the npt crrent, of the power factor λ and of the effcency η on the otpt power and npt voltage. Fg.9: osses of the power components for dfferent lne-tolne npt voltages. The dstrbton of the losses to the power components gven for dfferent npt voltages s shown n Fg.9. At low npt voltages the loss balance s domnated by the condcton losses of the power transstors whch cold be lowered by connectng two devces n parallel. redcton of the volme of the npt ndctors wold be overcompensated by the ncrease of the heat snk volme beng reqred for remanng a gven power semcondctors jncton temperatre at hgher losses. A hgher converter power densty cold be acheved by employng S Schottky dodes as free-wheelng dodes. Ths however wold reqre a low ndctance wrng of the power semcondctors other than a P board n order to allow a fll tlzaton of the hgh swtchng speed. There, also the d M /dtmmnty of the solated gate drve crcts wold have to be consdered n detal. Accordng to Fg. for the combnaton of a oolmos power transstor and a S Schottky Dode n a boost converter topology a rate of change of the common mode voltage of d M /dt >4kV/µs does occr. Therefore, commercally avalable optcally solated gate drve crcts whch are typcally specfed for d M /dt <5kV/µs cold only be employed n combnaton wth a common-mode flter (cf. Fg.(c)). In case an solaton of the otpt voltage has to be provded, for realzng a rectfer system wth hgh power densty alternatvely to the VIENNA Rectfer a three-level Y-Rectfer (cf. Fg.) whch p to now has not been analyzed n the lteratre shold be consdered. There, for operaton n the Eropean 4V rms (lne-tolne) mans 3V power semcondctor technology cold be employed for the free-wheelng dodes and the power transstors. As compared to the VIENNA Rectfer the system does allow a redcton of the ndctance of the npt ndctors by a factor of 5(!) de to the lower transstor trn-off voltage and/or low swtchng losses and de to the larger nmber of swtchng states avalable for the npt voltage formaton. On the other hand the system shows hgher condcton losses than the VIENNA Rectfer de to hgher nmber of power semcondctors lyng n the crrent path. -p S -p S - S - S S S Fg.: Three- evel Y-Rectfer (cf. also Fg.). F M R Photocopler ogc Drve D D The hgh redndancy of swtchng states concernng the npt voltage formaton (cf. Fg.2) does allow a balancng of the partal otpt voltages as well as an eqal dstrbton of the total otpt power to the phase systems. A detaled comparatve evalaton of the three-level Y-Rectfer and the VIENNA Rectfer wll be pblshed by the athors n the near ftre. α α2 β 2 3 (c) Fg.: Swtchng behavor of a oolmos power transstor (Infneon, SPW47N62) n combnaton wth two S freewheelng dodes SD6S6 connected n parallel for applcaton n a boost converter topology. Shown are transstor voltage S (V/dv), transstor crrent S (2A/dv) and the transstor swtchng power loss p S (kw/dv) for trn-on and trn-off. Frthermore shown: common mode flterng for lowerng the d M /dt occrrng across the photocopler. It has to be ponted ot that an ncrease of the swtchng freqency wold not reslt n a lower overall converter volme as the α β β 6 γ α 6 γ 6 γ 2 δ γ 3 γ 4 γ 5 β 5 α 5 β 3 β 4 α 4 Fg.2: Inpt voltage space vectors of the three-level Y-Rectfer n comparson to the VIENNA Rectfer (α and δ). The redndancy r of swtchng state δ s r δ =, for the vectors β and γ we have r β =2 and/or r γ =6.

4 A frther possblty of ncreasng the power densty of boost-type PWM rectfer systems s gven by the mnmzaton of the volme of the mans sde flter attenatng condcted EMI emssons. There, t s mportant to pont ot that the realzaton of the npt ndctors on a three-lmb magnetc core does not show a common-mode (zero-seqence) mpedance n case the stray ndctance of the phase wndngs and the yoke flx s neglected (cf. Fg.3). Therefore, a three-phase realzaton s of no drect advantage as compared to employng ndvdal ndctors n each phase. U V W U2 V2 W2 3 3 R S T 2 In contrast the applcaton of zero -rpple technqes whch for the sake of clearness are shown n Fg.4 and Fg.5 for a D/D boost converter does allow a sgnfcant redcton of the EMI flter volme and losses. There, by arrangng a secondary wndng s on the npt ndctor p of the PWM rectfer and by realzng a defned magnetc coplng of both wndngs wth the help of an = = axlary ndctor σs (cf. Fgs.4(c) and 5(c)) a two-stage flter can be realzed (cf. eqvalent crcts Fgs.4 and 5). There, only p s carryng the load crrent. The crrent n s (and/or σs ) does not show a D component, the rms vale of s Fg.3: Realzaton of a three-phase ndctor employng a threelmb magnetc core and common-mode eqvalent crct. Fg.4: Zero -rpple npt flter of a D/ D boost converter as proposed n [6]. As zero -rpple condton we have s =M. Ths s dentcal to conventonal zero rpple flterng accordng to Fg.4. The advantage of the approach shown as compared to Fg.4 s a lower nmber of trns N s ; however, the crrent n p does show a swtchng freqency rpple. Fg.5: onventonal zero -rpple npt flter [7] shown for a D/D boost converter. As zero-rpple condton we have s =M. As compared to the realzaton depcted n Fg.3 the flter reqres a hgher nmber of trns s, however no swtchng freqency rpple s present n the crrent carred by the npt ndctor p. only determned by the rpple of the npt ndctor wthot flter. Therefore, at very low overall volme a flter attenaton n the range of 6 8d can be acheved. A detaled analyss of the applcaton of zero -rpple technqes n three-phase boost-type PWM rectfer systems wll be the topc of a paper to be pblshed n near ftre. 3. Three-Phase ck+oost-type PWM Rectfer The fncton of a boost-type PWM rectfer system n prncple s dependent on a D otpt voltage level beng hgher than the ampltde of the mans lne-to-lne voltage. Therefore, n case the otpt voltage shold be vared n a wde range a bck-derved system and/or a combnaton of a bck-type and a boost-type converter topology has to be employed. U, F F F, N, S =R S T F, N N N, In [8] startng from a phase modlar topology (cf. Fg.6) a ndrectonal bck+boost PWM rectfer system (cf. Fg.6) has been proposed where analogos to the VIENNA Rectfer only a sngle power transstor s employed per phase for shapng the npt crrent. y ntegraton of a D/D boost converter stage nto the converter otpt a snsodal shape of the mans crrent can be mantaned also n the case of a phase loss. Therefore, the system cold be employed for feedng the varable D voltage lnk of sqare-wave nverter drves for HVA applcatons as well as for the realzaton of the npt stage of wde npt voltage range hghpower telecommncatons power spply modles. There, the hgh freqency solaton of the otpt voltage advantageosly cold be realzed as known from sngle-phase PWM rectfer systems wth snsodal npt crrent and typ V D otpt. Frther advantages as compared to boost-type systems are the possblty of a drect pre-chargng of the otpt voltage at start-p and/or of an overcrrent lmtaton n the case of an otpt voltage short crct condton. For the trn-on state of the power transstor S the fncton of a brdge leg of the crct shown n Fg.6 s eqvalent to the brdge leg of a conventonal dode brdge (cf. Fg.7). Accordngly, the crrent beng mpressed by the bck+boost ndctor can be dstrbted to the mans phases by proper PWM where after lowpass flterng a snsodal shape of the mans crrent does D F S D + I U Fg.6: Modlar three-phase bck+boost rectfer and drect three-phase realzaton accordng to [8].

5 , N, 3 F Û,, U * g * * * lm+ * + * + * p lm f c kpi, kii /x m peak scale to + detecton I max max P lm p * k PU, k IU + U * max PWM max U * δ j δ N Fg.2: Strctre of the control of a threephase bck+boost rectfer garanteeng nty power factor operaton also nder heavly nbalanced mans condton and/or for loss of a mans phase. For the sake of clearness the actve dampng of the npt flter s not shown. reslt. Therefore, for proper dmensonng of the flter capactors the system shows a power factor of λ.. U, S = on U, esdes the swtchng states of the power transstors also the npt voltage condton does take nflence on the formaton of the npt phase crrents U,. The npt crrent space vectors beng avalable for N,R >, N,R > N,S > N,T are depcted n Fg.8. The redndancy of swtchng states concernng the resltng npt crrent condton can be employed for an optmzaton of the system behavor. U,() = U,() = U,() = U,() δ () U,() I U,() π/3 π/6 U,() * U,() U ϕ U δ () U,() U,() R π/6 As shown n [9] for remanng always the power transstor of the phase showng the lowest absolte nstantaneos vale n the onstate (cf. Fg.9) a mnmm rms vale of the npt flter capactor voltage rpple and of the bck+boost ndctor crrent rpple s acheved for gven swtchng losses. N, U N N,R N,S N,T N,ST N,TR N,RS π S,clamped The strctre of the rectfer control [] s shown n Fg.2. Analogos to Fg.5 the control s related to phase qanttes. Agan, an npt condctance reference vale g* beng essentally constant over a mans perod s determned whch does provde the bass for 2π ϕ U Fg.7: For the trn-on state of the power transstor S the fncton of a brdge leg s eqvalent to the brdge leg of a conventonal dode brdge. Fg. 8: Space vectors avalable for the formaton of the npt phase crrents for N,R >, N,R > N,S > N,T. Fg.9: Optmm control of the bck+ boost rectfer. The brdge leg wth the lowest absolte vale of the correspondng phase voltage s clamped n the trnon state. the calclaton of the reference vale * of the crrent n the bck+boost ndctor where the actal mans voltage condton s consdered. For asymmetrc mans and/or loss of a phase,.e. twophase operaton, the maxmm otpt voltage ū max of the bck-stage s n ntervals of a mans perod lower than the otpt voltage reference vale U O *. The desred otpt voltage therefore only can be acheved by actvatng the boost stage (cf. Fg.2). 4V V 4V 2A F,R F,T F,S N,R A N,T N,S. not actve actve not actve δ Act,.5 δ δ FW δ= δ ms 2ms 2ms Act,2 ms Fg.2: Smlaton of the statonary operatng behavor of the bck+boost rectfer for symmetrc mans and falre of mans phase T. δ denotes the relatve trn-on tme of the boost stage power transstor, δ Act, δ Act2 and δ FW do denote the relatve on-tme of the bck-stage crrent-formng states and of the free-wheelng state. Reslts of an expermental analyss of the rectfer prototype (cf. Fg.22) are shown n Fg.23 and Fg.24. For the falre of a mans phase (loss of phase T) the D lnk crrent assmes the shape shown n Fg.2 whch s characterzed by a plsaton wth twce the mans freqency and the system contnes to draw a snsodal crrent lyng n phase wth the remanng mans lne-to-lne voltage. Fg.22: Prototype of the bck+boost rectfer system realzed n IGT technology (swtchng freqency f P = 23.4kHz) and desgned for wde npt voltage range U N,l-l = 28 48V rms and 6kW/ 4V D otpt. Overall dmensons: 34x6x2cm 3 correspondng to a power densty of ρ=.92kw/dm 3. The system control s realzed by a dgtal sgnal processor (not shown). For an npt power of P O 2kW the rectfer system shows a power factor of PF=λ.98. For hgh npt voltage and/or low otpt

6 A-A onverter F,R F,T N,S N,T D nk Energy Storage No D nk Energy Storage Matrx onverter F,S N,R VSR/VSI SR/SI onventonal (Drect) Indrect Sparse Very Sparse Inv. nk Ultra Sparse Fg.23: Expermental analyss of the rectfer operatng behavor for loss and reconnecton of mans phase T. Shown are the npt flter capactor voltage F, (25V/dv), the otpt voltage O (V/dv) and the mans phase crrents N, and the D lnk crrent (5A/dv). Operatng condton: 33V rms lne-to-lne npt, 2.2kW/4V D otpt. Fg.25: lassfcaton of A-A converter topologes. whch s not avalable for M and whch does allow to mplement a commtaton strategy of low complexty n order to ensre contnty of the load crrent and/or to avod a short crct of a lne-to-lne npt voltage. Effcency η /.96 U N,ll = 45 V Power Factor PF / V V 33 V Otpt Power P / kw V U N,ll = 45 V Otpt Power P / kw Fg.24: Dependency of the effcency η and of the power factor PF(=λ) of the system shown n Fg.22 on the otpt power and on the npt voltage (U O =4V). a b c A Fg.26: Strctre of the power crct of the conventonal matrx converter (M) employng 8 npolar trn-off power semcondctors and 8 dodes. power the npt crrent does show a relatvely hgh share of the npt flter capactor crrent, accordngly lower vales of the power factor do occr. For P O >kw,.e. for an otpt power beng hgher than 2% of the rated power and for rated npt voltage U N,l-l =4V rms the effcency s close to η=96%. For low npt voltage de to relatvely hgh condcton losses of the power transstors and de to hgh ohmc losses n the bck+boost ndctor wndng a relatvely low effcency does reslt. Therefore, by employng hgh swtchng speed and/or ltra fast recovery power semcondctors only the effcency at hgh npt voltages (and/or hgh power semcondctor swtchng voltage) cold be mproved. In smmary, for the realzaton of a PWM rectfer system wth hgh effcency and wde npt voltage range and low otpt voltage or wde otpt voltage range the system depcted n Fg.6 shold be comparatvely evalated concernng losses and volme aganst a combnaton of a VIENNA Rectfer and a nonsolated D/D bck converter where the VIENNA Rectfer otpt voltage shold be vared n dependency of the mans voltage n order to mnmze the power transstor losses. 4. Three-Phase Sparse Matrx A-A onverter For the converson of the three-phase mans voltage nto a threephase voltage systems of defneable freqency and ampltde a combnaton of a voltage D lnk or crrent D lnk PWM rectfer and PWM nverter or a matrx converter topology cold be employed (cf. Fg.25). onventonal matrx converters (M, cf. Fg.26) do employ a large nmber of trn-off power semcondctors and are characterzed by a complex mlt-stage commtaton strategy. In contrast, Sparse Matrx onverters (SM) as proposed n [] (cf. Fg.27) do show a sgnfcantly lower realzaton effort and frthermore do provde a degree of freedom for control The advantages of a Sparse Matrx onverter as compared to a conventonal D voltage lnk A-A converter topology are mmedately obvos from Fg.28. In case the D lnk voltage s mpressed by a D lnk capactor swtchng losses do occr for the rectfer as well as for the nverter stage. In contrast, for the p a b c a b c s apa a s bnb s cnc n s pa s p s p Fg.27: Topology of the Sparse Matrx onverter (SM, []) and of the Ultra Sparse Matrx onverter (USM, []). The USM s lmted to ndrectonal power flow,.e. rectfer operaton. SM swtchng losses only do occr for the npt or for the otpt stage. Therefore, the man advantage of a SM as compared to a conventonal D lnk converter topology s not a lower volme of the passve power components (as also for the SM for defnng the npt flter characterstc ndependent from the nner mans mpedance npt ndctors have to be provded) bt a potentally A A A

7 hgher effcency of the energy converson at hgh swtchng freqency. As a dsadvantage of the SM (and of the M) one has to accept a relatvely low maxmm ampltde of the otpt voltage. U U U U U U U2 U2 U2 (c) Fg.28: D-D eqvalent crct of a three-phase A-A converter wth D voltage lnk and of a SM. The flter capactor of the SM cold also be employed as a D lnk capactor (wth low energy storage capablty). Frthermore shown: fnctonal eqvalent crct (c) of. sapa sbnb scnc spa sp sp ab A - ac - A sapa sbnb scnc spa sp sp ab A - - ac A ab -3 ba tµ = 2 TP TP τab τac τab τac cb ca +3 ac bc a b c -6 ab ba tµ = 2 TP TP τab τbc τab τbc cb ac bc ca +6 Fg.3: Modlaton of the SM for generatng an otpt voltage of hgh ampltde and for low otpt voltage. the D lnk voltage ths does reslt n a redcton of the otpt stage swtchng losses. A comparatve evalaton of both modlaton schemes concernng swtchng losses and the resltng rms vale of the otpt crrent and npt capactor voltage rpple s the topc of crrent research and wll be pblshed by the athors n near ftre. Reslts of a dgtal smlaton and of an expermental analyss of the SM as derved from a kw prototype (cf. Fg.3) for modlaton accordng to Fg.3 are compled n Fg.32. b c a Fg.3:Protoype of a kw SM. The system control (not shown) s realzed by a DSP n combnaton wth programmable logc devces. The overall dmensons of the system ncldng the npt flter are 24x2x8.5cm 3 resltng n a power densty of ρ=2.5kw/dm 3. τ(), ab τab τac τ(), ab t µ = τ(), ab τ(), ac τ(), ac τ(), ac T P 2 τ(), ab τ(), ab t µ = Fg.29: ommtaton strateges of a SM shown at the example of typcal swtchng state seqences occrrng wthn a plse half nterval. ommtaton of the npt stage at zero D lnk crrent = [2] and commtaton ntated by the npt stage. ommtaton strateges of the SM are shown n Fg.29. In case the otpt stage s swtched nto the free-wheelng state n advance to the npt stage commtaton the change of the swtchng state of the npt stage s at zero crrent, =. Therefore, (deally) no swtchng losses do occr (cf. Fg.29, the dead tme between trn-off of S bnb and trn-on of S cnc whch has to be consdered for a practcal applcaton s not shown). Alternatvely, for postve D lnk crrent the otpt stage cold be forced nto free-wheelng operaton also by trnng off a power transstor of the npt stage (cf. Fg.29). In case the swtchng state of the otpt stage s not changed, the npt stage frthermore takes over the swtchng losses for applyng the sbseqent mans lne-to-lne voltage to the D lnk and/or to the load. Ths allows to balance the thermal stress on the semcondctors of the SM npt and otpt stage. A frther degree of freedom of the modlaton of the SM s obvos from Fg.3. For the formaton of an otpt voltage of hgh ampltde n each plse half perod the lne-to-lne mans voltages showng the hghest and the second-hghest nstantaneos vale are employed (cf. Fg.3). In case an otpt voltage wth low ampltde has to be generated the lowest postve and the second hghest postve lne-to-lne voltage are appled to the D lnk (cf. Fg.3). As the swtchng losses of the otpt stage are n a frst approxmaton proportonal to the trn-off,.e. to τ(), FW τ(), ac τ(), ac T P 2 A, A A 5ms ms 5ms ms A ; A A (c) j=a =a b c Fg.32: Dgtal smlaton, and expermental verfcaton (c),(d) of the operatng behavor of a SM. Operatng condton: U,l-l =4V rms, f =5Hz, U 2 = 95V, f 2 =Hz, P=2kW, swtchng freqency f P =5.6kHz, ohmc mans behavor, phase dsplacement of otpt crrent and otpt voltage fndamental Ф 2. Accordng to Fg.33 [3] for a fll thermal tlzaton of the power semcondctors (jncton temperatre T j =2 for a heat snk temperatre of T H =75, U,l-l =4V rms ) of a kw SM realzed n 2V IGT technology and a swtchng freqency of f P =2kHz a very hgh overall effcency of η 95% cold be acheved (operatng condtons: formaton of the maxmm otpt voltage U 2,l-l = 3/2 U,l-l, modlaton accordng to Fg.3, j=a j N, j (d)

8 Î 2,max ξ [A] [%] η=.9 η= Max. rrent Ampl f P [khz] Rato ξ Sw.-/Total osses of lmtng Valve [%] 5 Rato ξ Sw.-/Total osses of entre onverter [%] onst.effcency η Fg.33: Maxmm admssble otpt crrent ampltde of a SM realzed n IGT technology n dependency on the plse freqency. Modlaton as shown n Fg.3. Frthermore shown: effcency η and rato ξ of swtchng and total losses. For detals see [3]. feedng of a permanent magnet synchronos machne,.e. phase dsplacement of otpt crrent and otpt voltage fndamental Ф 2 ). In the corse of frther research a realzaton of the SM n S-technology has to be consdered whch does allow operaton at hgh ambent temperatre as present, e.g., for the motorntegrated converter systems and facltates swtchng freqences n the range of f P =..2kHz mnmzng the npt flter volme. However, the matrx converter concept bascally mght replace conventonal D lnk nverter drves n ftre only n areas where motor and nverter are developed by a sngle manfactrer for specfc applcatons. 5. onclsons For the realzaton of ltra-compact and/or hgh-freqency and hgh effcency three-phase PWM converter system besdes novel crct topologes and modlaton and control schemes as dscssed n ths paper, novel low-ndctance nterconnecton technologes, novel concepts of magnetc and electromagnetc components, and novel concepts for packagng and coolng have to be developed. There, electromagnetc and thermal smlaton wll be of ncreasng mportance for the converter desgn. Frthermore, dgtal smlaton wll be employed more and more also n parallel wth the expermental analyss of converter systems as for hghly ntegrated realzatons crrents and voltages n general cold not be acqred drectly. Ths fact also shold be consdered by the development of novel ndrect measrement technqes, e.g. for determnng the crrent n a condctor and/or power semcondctor from a near-feld measrement. Fg.34: Interactve Power Electroncs Semnar (PES) on fndamentals of power electroncs. PES s nder frther development at the ETH Zrch and s avalable at no costs at esdes technologcal aspects the edcaton of ftre engneers s of paramont mportance for ensrng a frther contnos and dynamc development of the feld. There, n order to acheve a hgh effcency of the learnng process new meda and nformaton technology, e.g. n the form of nteractve web-based smlaton (cf. Fg.34) shold be employed. Frthermore, dgtal smlaton Fg.35: Electromagnetc smlaton of the magnetc core of a seres /parallel resonant converter and thermal smlaton of a mlt-chp power modle as performed by stdents n the 4 th semester on electrcal engneerng at the ETH Zrch. shold not be sed only for crct- and control-orented smlaton bt also be sed for showng the thermal and electromagnetc desgn of power electronc systems (cf. Fg.35). Fnally, for the edcaton of ftre engneers laboratory corses based on ndstry related hardware (cf. Fg.36) are a strct reqrement. Sch corses shold clearly show all parastc effects whch mght occr n ndstral systems and shold pont ot the mportance of a practcal verfcaton of all theoretcal reslts n the feld of power electroncs. 6. References Fg.36: Hghly versatle laboratory setp for teachng bascs of power electroncs developed at the ETH Zrch. The system does allow to analyze all basc sngle- and three-phase PWM A/ D converters as well as solated and nonsolated D/D converter topologes. [] Kolar, J.W., and Ertl, H.: Stats of the Technqes of Three-Phase Rectfer Systems wth ow Effects on the Mans. Proceedngs of the 2 st IEEE Internatonal Telecommncatons Energy onference, openhagen, Jne 6-9, paper No. 4- (999). [2] Kolar, J.W., and Zach, F..: A Novel Three-Phase Three-Swtch Three-evel Unty Power Factor Rectfer. Proceedngs of the 28 th Internatonal Power onverson onference, Nremberg, Jne 28-3, pp (994). [3] Zhao, Y.,, Y., and po, T.A.: Forced ommtated Three-evel oost Type Rectfer. Record of the 28 th IEEE Indstry Applcatons Socety Annal Meetng, Toronto, Oct. 2-8, Vol. II, pp (993). [4] Mnböck, J., Stögerer, F., and Kolar J.W.: A Novel oncept for Mans Voltage Proportonal Inpt rrent Shapng of a VIENNA Rectfer Elmnatng ontroller Mltplers. Proceedngs of the 6 th IEEE Appled Power Electroncs onf., Anahem, March 4-8, Vol., pp (2). [5] Kolar, J.W., Drofenk, U., and Zach, F..: VIENNA Rectfer II A Novel Sngle-Stage Hgh- Freqency Isolated Three-Phase PWM Rectfer System. IEEE Transactons on Indstral Electroncs, Vol. 46, No. 4, pp. -8 (999). [6] Schtten, M.J., Stegerwald, R.., and Sabate, J.A.: Rpple rrent ancellaton rct. Proceedngs of the 8 th IEEE Appled Power Electroncs onference, Mam, Feb. 9-3, Vol., pp (23). [7] Kolar, J.W., and Zach, F..: Novel Aspects of an Applcaton of Zero-Rpple Technqes to asc onverter Topologes. Proceedngs of the IEEE Power Electroncs Specalsts onference, St. os (MI), USA, Jne (997). [8] amann, M., Drofenk, U., and Kolar, J.W.: A New Wde Inpt Voltage Range Three-Phase Unty Power Factor Rectfer Formed by Integraton of a Three-Swtch ck-derved Front-End and a D/D oost onverter Otpt Stage. Proceedngs of the 22 nd IEEE Internatonal Telecommncatons Energy onference, Phoenx, Sept. -4, pp (2). [9] amann, M., and Kolar, J.W.: omparatve Evalaton of Modlaton Methods for a Three- Phase / Swtch ck Power Factor orrector oncernng the Inpt apactor Voltage Rpple. Proceedngs of the 32 nd IEEE Power Electroncs Specalsts onference, Vancover, Jne 7-2, Vol. 3, pp (2). [] amann, M., and Kolar, J.W.: A 5kW Three-Phase ck+oost Telecommncatons Power Spply Modle Inpt Stage Mantanng Unty Power Factor Under Falre of a Mans Phase. To be pblshed at the Internatonal Power onverson onference, Nremberg, May 2-22 (23). [] Kolar J.W., amann M., Schafmester F., and Ertl H.: Novel Three-Phase A-D-A Sparse Matrx onverter. Proceedngs of the 7th Annal IEEE Appled Power Electroncs onference and Exposton, Dallas (TX), USA, March - 4, Vol. 2, pp (22). [2] We,., and po, T.A.: A Novel Matrx onverter Topology wth Smple ommtaton. Record of the IEEE Indstry Applcatons Socety Annal Meetng, hcago, Sept. 3 Oct. 4, Vol. 3, pp (2). [3] Schafmester, F., Herold, S., and Kolar, J.W.: Evalaton of 2V-S-IGTs and 3V-S- JFETs for Applcaton n Three-Phase Very Sparse Matrx A-A onverter Systems. Proceedngs of the 8th IEEE Appled Power Electroncs onference, Mam each (F), USA, Feb. 9-3, Vol., pp (23).