Experimental Verification of Conduction Noise of Three-level V-connection Rectifier-Inverter System

Transcription

1 Expeimenal Veificaion of Conducion Noie of Thee-level V-connecion Recifie-Invee Syem Jun-ichi Ioh, Huynh Dang Minh, Daiuke Sao Depamen of Elecical, Eleconic and Infomaion Engineeing Nagaoka Univeiy of Technology Nagaoka, Japan Abac Thi pape dicue he conducion noie educion poibiliy of a anfome-le hee-level V- connecion ecifie-invee yem. Thi cicui i ued fo he main cicui in an Unineupible Powe Supply (UPS) yem. The efficiency of hi cicui i highe han ha of he convenional hee-phae ecifie-invee cicui due o no iolaed anfome in oupu ide. In hi pape, o veify he conducion noie of he V-connecion yem, a heoeical analyi abou he common-mode cuen which baed on he common-mode equivalen cicui, i dicued. Baed on hi, he compaion of he conducion noie beween he hee-level V- connecion Back To Back (BTB) yem and he convenional hee-level hee-phae connecion BTB yem i aumed. In addiion, he conducion noie of wo yem ae meaued and compaed in ode o confim he aumpion. A a eul, i i confimed ha he conducion noie which i geneaed fom he hee-level V-connecion ecifie-invee cicui i highe han ha of he convenional hee-phae ecifie-invee cicui. Keywod Mulilevel convee, V-connecion ecifieinvee, conduced emiion, leakage cuen I. INTRODUCTION In ecen yea, due o he apid developmen of he infomaion ociey, he demand of Online Unineupible Powe Supply (UPS) ha been inceaing. UPS which enue he abiliy of he powe upply and avoid daa lo due o powe failue, ha been applied in many eve yem all ove he wold [-2]. Howeve, in hi kind of yem, he iolaion anfome i equied a he oupu ide, which accoun fo abou 4% of he UPS oal weigh. Fuhemoe, he uiliy of he iolaion anfome inceae he ize of UPS. In addiion, he iolaion anfome caue he conan lo which lowe he powe conveion efficiency [3]. In ode o olve above poblem, many mehod ha been popoed [2-4]. One of hoe i he concep of he anfomele wo-level V-connecion BTB yem [3-4]. In hi yem, by gounding he common phae, i i poible o emove he iolaion anfome. A a eul, high efficiency and miniauizaion of UPS can be achieved. Howeve, he DC link volage in he V-connecion BTB yem become wo ime highe han ha in he hee-phae connecion BTB yem. A a eul, high volage wiching device ae equied. In ode o olve hi poblem, he hee-level V-connecion BTB yem ha been popoed [3]. Compaed wih he wo-level yem, he numbe of he wiching device i inceaed. Howeve, due o he chaaceiic of he muli-level cicui, he volage applied aco he wiching device become /(n) ime of he DC link volage. Hee, n i he numbe of level of he cicui. Theefoe, low volage aing device can be applied. On he ohe hand, i i confimed ha he efficiency of he hee-level V-connecion BTB yem can be impoved by 7.9% compaed wih he hee-phae connecion BTB yem [4]. Howeve, becaue of he main cicui of UPS, he evaluaion of he conducion noie which i geneaed by he hee-level V-connecion BTB yem i neceay. Hence, he meauemen and compaion of he conducion noie beween he hee-level V-connecion BTB yem and he convenional hee-level hee-phae connecion BTB yem mu be conduced. In hi cae, he conducion noie i evaluaed by he conduced emiion which anmi in he powe line. Theefoe, baed on Sandad CISPR 22, he conduced emiion in fequencie fom 5 khz o 3 MHz i meaued and evaluaed. The V-connecion BTB yem ha many advanage in em of he efficiency impovemen and ize educion. Howeve, i eem ha he conduced emiion of he V- connecion hee-level invee ha no been epoed in pa wok. Epecially, he behavio of he neual poin volage of he V-connecion hee-level invee ha no been dicued compaed wih hee-phae hee-level invee. In addiion, he convenional mehod o evaluae he conduced emiion of he powe convee yem i meauing he conduced emiion and epoducing i by imulaion [5-8]. In hi mehod, he imulaion eul can epoduce he expeimenal eul faily exacly in he imple yem. Howeve, i doe no claify he eaon of he geneaion of he common-mode volage. Theefoe, he mechanim of he geneaion of he commonmode volage i no clea. Hence, i caue difficulie in finding ou he mehod o educe he conduced emiion of he yem by uppeing he common-mode volage. In hi pape, in ode o eveal he behavio of he conduced emiion of he V-connecion hee-level BTB yem, a heoeical analyi abou he common-mode cuen which baed on he common-mode equivalen cicui, i dicued compaed wih he hee-phae hee-level BTB yem. The neual poin poenial vaiaion of boh yem i inveigaed and fomulaed in ode o claify he geneaion of he common-mode volage. Noe ha he common-mode volage i he ouce of he common-mode cuen in he yem. Moeove, he common-mode cuen dominae he conduced emiion. Hence, baed on hi analyi, he compaion eul of he conduced emiion beween he heephae connecion BTB yem and he V-connecion BTB

2 yem can be aumed. Afe ha, he expeimenal eul of he common mode leakage cuen and he conduced emiion in wo yem ae demonaed. Due o he meauemen eul, he aumpion abou he compaion eul of he conduced emiion beween wo yem i confimed. II. MAIN CIRCUIT CONFIGURATION AND CONTROL STRATEGY Fig. how he cicui diagam of a hee-level heephae connecion BTB yem, and a hee-level V-connecion BTB yem, epecively. In ode o obain he ame oupu volage, he DC volage of he hee-level V-connecion BTB yem i e o wo ime highe han ha of he hee-phae connecion BTB yem. Theefoe, in he hee-level V- connecion BTB yem, high volage wiching device ae equied. Howeve, in hi pape, he ame volage aing wiching device ae applied in boh yem in em of he compaion of he conduced emiion pefomance depending on he cicui opology. In addiion, he ame wiching fequency i applied egadle of he connecion mehod. Fig. 2 how he conol block diagam of he ecifie uni in hee-level V-connecion BTB yem. The ecifie uni i conolled by he Auomaic Cuen Regulao (ACR) and he Auomaic Volage Regulao (AVR) o obain he inuoidal inpu cuen and o egulae he DC link volage. In ode o obain he high inpu powe faco, he phae efeence of he cuen command value of he ACR ae calculaed fom he inpu volage phae. On he ohe hand, he invee uni i conolled by open-loop, and he modulaion cheme i unipola PWM modulaion, which ha he caie change beween and a poiive peak, while he efeence i alway poiive [3]. In he hee-phae connecion BTB yem, he conol aegy of he ecifie uni i he ame a he V- connecion BTB yem. Howeve, he cuen command value of he S phae i deived fom he cuen command value of R phae and T phae by (). * * * i ( i i )... () whee i *, i *, i * ae he inpu cuen command. When caying ou he expeimen, in ode o change fom he hee-phae connecion BTB yem o V-connecion BTB yem, he PWM ignal which conol he ON / OFF ae of he wich of S phae and V phae module in he hee-phae connecion BTB yem, will be e o OFF ae. III. EVALUATION SYSTEMS A. Configuaion of evaluaion yem Fig. 3 how yem configuaion o evaluae he conduced emiion and he place o obeve he commonmode leakage cuen. Thee yem ae buil fo imulaing he cicui of he UPS. Theefoe, hee ae wo file a he inpu and oupu o eain he EMI noie which i geneaed fom he wiching of he main cicui. In addiion, an oupu Low-pa File (LPF) i pu in ode o obain he inuoidal wavefom. The leakage inducance of he oupu anfome i ued a he file L in he LPF. Fig. 3(b) how he V-connecion BTB yem. I alo ha wo file a he inpu and oupu, and a LPF a he oupu. Howeve, in he V-connecion yem, an induco v v v i i i Edc/2 Edc/2 (a)thee-level hee-phae-connecion BTB yem v v v i i i Edc/2 Edc/2 iu iu iv iv iw iw vu vv vw vu vv vw (b)thee-level V-connecion BTB yem Fig.. Main cicui configuaion, which ha he PWM ecifie uni a he inpu and he PWM invee uni a he oupu (BTB yem) E dcef - E dcde AVR I * _ef x I - _ef I pu I * _ef x - I _ef I pu in ACR ACR x q in E dcae an v α,v β Edcde 3Φ/αβ Fig.2. Conol block diagam fo hee-level V-connecion ecifie-invee. I coni of AVR (o conol he DC link volage) and ACR (o conol he inpu cuen) which ha a ame inducance of he leakage inducance of he anfome in he hee-phae connecion BTB yem i needed a he file L. Noe ha i CM_heaink i he leakage cuen fom he hea ink, i CM_oupu i he leakage cuen of he oupu file, i CM_inpu i he leakage cuen of he inpu file, and i CM_ i he leakage cuen which flow ino Line Impedance Sabilizaion Newok (). In addiion, i i impoan o achieve he ame ay capaciance beween he hea ink and wiching device egadle of he connecion mehod. Theefoe, when changing he connecion mehod fom hee-phae connecion o V-connecion, he common phae (S phae and V phae) i conneced o he neual poin of elecolyic capacio, and wiching device of he common phae (S phae and V phae) ae alway uned off. Fig. 4 how he cicui configuaion of he file. The file ha hee pa: X capacio, Common Mode Choke (CMC) and Y capacio. The X capacio i ued o uppe he Diffeenial Mode (DM) cuen, while CMC and Y capacio i ued o uppe he Common Mode (CM) cuen. In addiion, he deign of file i baed on Ref.[2]. Hee, he X capacio capaciy i deigned baed on x v ef v ef v v

3 an allowable lead angle of cuen φ becaue i educe he powe faco a he ligh load [2]. In addiion, he Y capacio capaciy i deigned baed on he accepable leakage cuen [2]. B. Common-Mode equivalen cicui Fig. 5 how he equivalen cicui fo he common-mode volage and cuen of boh yem. Noe ha he polaiy of he ecifie common-mode volage v ec i oppoie o ha of he invee common-mode volage v inv []. Nex, L L and R L ae he CM inducance and eiance value of he boo eaco on he inpu ide of he hee-phae connecion invee, while L L2 and R L2 ae he CM inducance and eiance value of he V-connecion invee. Noe ha hee i unbalance beween he value of L L, R L and L L2, R L2. I i becaue in he hee-phae connecion BTB yem, hee ae hee boo eaco on he inpu, while hee ae ju wo boo eaco in he V-connecion BTB yem. In addiion, R load and L load ae he CM inducance and eiance value of he RL load. Hee, i can be conideed a he paallel cicui of L, C and R. In addiion, he volage which appea aco R i he conduced emiion volage. Fuhemoe, C GH, and C GH3 ae he paaiic capaciance beween he IGBT module and he hea ink [8]. They ae meaued beween hee oupu eminal of he IGBT module and he hea ink. Moeove, L, R ae he inducance and eiance of he inpu CMC, while L 2, R 2 ae he inducance and eiance value of he oupu CMC. Finally, L GH, L GF, L GF2 ae he ay inducance of he gounded line, while C GL, C GTan ae he ay capaciance of he load and he iolaion anfome. Fom Fig. 5, i can be known ha hee ae many CM cuen loop which flow aound in he yem. Howeve, fo impliciy, only he CM cuen which flow hough he ae conideed, becaue he volage of hi eiance i ued o analyze he conduced emiion of he yem. Theefoe, hee ae hee CM leakage cuen which ae conideed in hi cae: Loop : Geneaed fom invee file L ay capaciance of anfome C an (o no in V- connecion) // file // Load file gounded line inpu file // ecifie invee Loop 2 : Geneaed fom ecifie Boo eaco inpu file // Hea ink gounded line Say capaciance beween IGBT module and hea ink // 2C GH3 // C GH ecifie Loop 3 : Geneaed fom invee Say capaciance beween IGBT module and hea ink Hea ink gounded line inpu file // Boo eaco ecifie invee Fom 3 loop above, i can be conideed ha he inpu file play an impoan ole in bypaing he CM cuen which flow ou he powe upply, while he oupu file only bypae he CM cuen which flow o he load. In addiion, i can be known ha he ay capacio of he IGBT module C GH,, C GH3 and he ay inducance of he gounded line of hea ink L GH play an impoan ole in he geneaion of many CM leakage cuen. I i becaue if no G icm_ file Boo eaco icm_inpu Recifie Hea ink Invee Tanfome File C icm_heaink file icm_oupu (a)thee-level hee-phae-connecion BTB yem G icm_ file icm_inpu Boo eaco Recifie Hea ink Invee icm_heaink File L File C file icm_oupu (b)thee-level V-connecion BTB yem Fig.3. Cicui diagam when meauing conduced emiion, which ue common main cicui fo boh yem C X CMC Fig.4. file C Y gounding he hea ink, hee i only one loop of he CM leakage cuen which exi in he CM equivalen cicui. Compaed Fig. 5(a) o Fig. 5(b), i can be een ha hee i unbalance beween hee-phae connecion BTB yem and V- connecion BTB yem: in he hee-phae BTB connecion yem, hee i a ay capacio of iolaion anfome C GTan on he oupu ide while hee i no a imila componen in he V-connecion BTB yem. Howeve, hi unbalance i negligible becaue he impedance of C GTan i alway much lage han he impedance of he oupu file conneced in paallel o he load. IV. NEUTRAL POINT POTENTIAL VARIATION Fom he CM equivalen cicui, i can be conideed ha he CM volage cuen pah and ay componen ae imila in boh yem. Theefoe, he diffeence in he magniude of he CM leakage cuen beween wo yem will be caued by he diffeence in he magniude of he CM volage ouce v ec and v inv. Noe ha v ec i he CM volage beween he neual poin of he powe upply and he neual poin, while v inv i he CM volage beween he neual poin of he load and he neual poin. Baed on hi, he analyi of he neual poin poenial vaiaion in boh yem i neceay. Becaue of he ymmeic of he BTB yem, only he analyi of he geneaion of v inv i needed fo dicuion. The analyi of he geneaion of v ec i imila. Only wo of he fou wiche of one phae ae uned on, and connec he oupu eminal o one of hee wiching ae: Poiive (oupu volage = E dc /2), Zeo (oupu volage = ), Negaive (oupu volage = -E dc /2). Uing wiching funcion S u, S v, S w o epeen he wiching ae of each phae U, V, W. In hi cae, S u, S v, S w can only have one of hee value {,, } a any ime. Hee, he wiching ae vaiable S u, S v, S w = when he oupu eminal of he coeponding phae i conneced o wiching ae Poiive; S u, S v, S w = when conneced o wiching ae Zeo and S u, S v, S w Load Load

4 L C file L R L C R C Main cicui v ec Neual poin v inv L file file L 2 R 2 L load /3 R load /3 R C Y /3 L GF C GH C GH3 C GH3 C GH C Y2 /3 L GF2 C GL L GH Loop Loop 2 Loop 3 L C file L R L C2 R C2 (a). Thee-phae connecion BTB yem Main cicui Neual poin v ec v inv L file file L 2 R 2 L load /3 R load /3 R C Y /3 L GF C GH C GH3 C GH3 C GH C Y2 /3 L GF2 C GL L GH Loop Loop 2 Loop 3 (b). V-connecion BTB yem Fig.5. Common-mode equivalen cicui in boh yem, he leakage inducance of he iolaion anfome in he hee-phae connecion i eplaced by file L in he V-connecion = when conneced o wiching ae Negaive. Thu, he neual poin poenial vaiaion v nout_mp of he hee-phae connecion can be caculaed by v nout _ MP E dc_ heecon ( S u S S )....(2) 6 whee E dc_heecon i he DC link volage of he hee phae connecion invee. Similaly, in he V-connecion invee, i can be conideed ha he wiching ae vaiable of V phae i alway equal zeo i.e. S v =, and he DC link volage E dc_vcon = 2E dc_heecon. Hence, (2) can be ewien a v nout _ MP E dc_ Vcon ( S u w v w S )...(3) 6 Baed on (2), i can be conideed ha in he hee-phae connecion invee, he maximum value of he neual poin poenial vaiaion v nout_mp = E dc_heecon /2 when he wiching ae of all hee phae i Poiive. In addiion, baed on (3), in he V-connecion invee, i can be conideed ha he maximum value of he neual poin poenial vaiaion v nout_mp = E dc_vcon /3 when he wiching ae of all wo phae i Poiive. Becaue he DC link volage of he V-connecion invee i wo ime highe han ha of he hee-phae connecion invee E dc_vcon = 2E dc_heecon, i can be concluded ha he maximum value of he neual poin poenial vaiaion v nout_mp of he V-connecion invee i highe han ha of he hee-phae connecion invee. On he ohe hand, he CM volage ouce v ec and v inv dominae he magniude of he CM cuen of each yem. Theefoe, i can be aumed ha he magniude of he CM cuen in he V-connecion BTB yem i highe han ha in he hee-phae BTB connecion yem. Moeove, he CM cuen dominae he geneaion of he conduced emiion. Baed on hi, i can alo be aumed ha he conduced emiion of he V-connecion BTB yem i highe han ha of he hee-phae connecion BTB yem. Table how he oupu volage ae of he neual poin poenial vaiaion v nout_mp of he hee-phae connecion invee. Fom able, i can be confimed ha hee ae even oupu volage ae in he hee-connecion invee. Table 2 how he oupu volage ae of he neual poin poenial vaiaion v nout_mp of he V-connecion invee. Fom able 2, i can be confimed ha he numbe of he oupu volage ae of he V-connecion invee i le han ha of he hee-phae connecion invee. Noe ha in able, he DC link volage of he hee phae connecion invee E dc_heecon = E dc, while in able 2, he DC link volage of he V-connecion invee E dc_vcon = 2E dc. Fig. 6 how he diibuion of he oupu volage ae of he neual poin poenial vaiaion v nout_mp wih epone o he oupu volage veco in boh yem. Noe ha hee i an individual mak which i ued o epeen fo each oupu volage ae. Compaing Fig. 6(a) o Fig. 6(b), i can be confimed ha he numbe of he wiching ae of he heephae connecion invee i moe han ha of he V-connecion invee. Baed on hi, i can be concluded ha he degee of

5 Table.Oupu volage ae of he neual poin poenial vaiaion v nout_mp of he hee-phae connecion invee. In hi cae, he DC link volage E dc_heecon = E dc U phae V phae W phae v nout_mp E dc /2 E dc /6 E dc /3 -E dc /2 -E dc /3 -E dc /6 Table 2.Oupu volage ae of he neual poin poenial vaiaion v nout_mp of he V-connecion invee. In hi cae, he DC link volage E dc_vcon = 2E dc U phae V phae W phae v nout_mp 2E dc /3 E dc /3-2E dc /3 -E dc /3 feedom of wiching in he hee-phae connecion invee i highe han ha of he V-connecion invee. V. EXPERIMENTAL RESULTS Table 3 how he expeimenal condiion. When meauing he conduced emiion, a combinaion beween a pecum analyze R33A (Advane Copoaion) and a i applied, and he noie meauemen i caied ou in a hielded oom. Fig. 7 how he meauemen eul of he neual poin poenial vaiaion. Fom Fig. 9, i can be confimed ha he neual poin poenial vaiaion of he V-connecion BTB yem i highe han ha of he hee-phae connecion BTB yem. Fig. 8 how he hamonic analyi eul of he CM leakage cuen of boh yem. Fom Fig. 8, i can be confimed ha he CM leakage cuen fom hea ink, he CM leakage cuen of inpu and oupu file of he heephae connecion BTB yem i lowe han hoe of he V- connecion BTB yem. I i becaue ha he neual poin poenial vaiaion of he V-connecion BTB yem i highe han ha of he hee-phae connecion BTB yem. The neual poin poenial vaiaion dominae he magniude of he CM volage. Hence, he CM volage ouce of he V- connecion BTB yem alo become highe han ha of he hee-phae connecion BTB yem. In addiion, he leakage cuen which flow ino i CM_ i he malle among he CM leakage cuen. Fom hi, he effec of bypaing he CM leakage cuen of he inpu file i confimed. Moeove, i can be known ha he CM leakage cuen of he hea ink i dominan in boh yem. I i becaue hi CM leakage cuen i geneaed fom he eonance of he ay capaciance of he IGBT module C GH,, C GH3 and he ay inducance of he gounded line of hea ink L GH. Fom Fig. 5, i can be een ha he CM leakage cuen of he hea ink ha a ynheic CM volage ouce v ec v inv. Theefoe, i become a dominan CM leakage cuen. Fig. 9 how he meauemen eul of he conduced emiion of boh yem. Fom Fig. 9, in all fequencie fom 5 khz o 3 MHz, i i confimed ha he conduced V3 Vwu V2 V6 V8 Vv Vw V5 V2 V V2 V8 V9 V5 b V24 V27 V2 V23 V V4 V7 V8 V V26 V4 V9 V3 V7 V22 V6 V25 (a). Thee-phae connecion invee V7 V9 V6 V4 Vwv b V5 Vvw V V3 V2 Vu a Vuv a E dc/2 E dc/3 E dc/6 -E dc/6 -E dc/3 -E dc/2 2E dc/3 E dc/3 -E dc/3-2e dc/3 (b). V-connecion invee Fig.6. Diibuion of he oupu volage ae of he neual poin poenial vaiaion in boh yem emiion of he V-connecion BTB yem i highe han ha of he hee-phae connecion BTB yem. In addiion, fom Fig. 9(a), in he hee-phae connecion BTB yem, hee ae he peak a 55 khz,.6 MHz and 5 MHz. Compaed wih Fig. 8(a), hee peak of he conduced emiion almo mached wih he peak fequencie of he CM leakage cuen meauemen eul. Moeove, in he fequencie below MHz, he endency of he leakage cuen wavefom, epecially he wavefom of he leakage cuen which flow ino i CM_, mach wih he conduced emiion meauemen eul. In he fequencie fom MHz o 3 MHz, he conduced emiion fom gae dive powe upplie become conideable [9], []. Theefoe, in he fequencie fom MHz o 3 MHz, he endency of he conduced emiion become diffeen fom he endency of he CM leakage cuen. Fom hee analye above, i can be concluded ha he CM leakage cuen dominae he geneaion of he conduced emiion, epecially in he fequencie below MHz. In he V-connecion BTB yem, i can alo be confimed ha he CM leakage cuen dominae he geneaion of he conduced emiion, in imila. VI. CONCLUSION In hi pape, he neual poin poenial vaiaion of he hee-level hee-phae connecion BTB yem and he heelevel V-connecion BTB yem wa dicued. A a eul, i i confimed ha he neual poin poenial vaiaion of he V- connecion BTB yem i highe han ha of he hee-phae connecion BTB yem. I caue he CM leakage cuen of he V-connecion BTB yem become highe. Hence, i can be concluded ha ince highe neual poin poenial vaiaion,

6 AC Volage (line -o-line) DC-link volage AC Volage (line -oline) & phae cuen powe Powe upply fequency fequency Swiching fequency Load IGBT module Table 3. Expeimenal condiion V-connecion Thee-phae 6 V 2 V 45 V, 6.4 A.6 kw 5 Hz 6 Hz 6 khz RL load (3 Ω, 5 mh) SK5MLI66T (Semikon) Neual poin poenial vaiaion V MP_nOUT [V] (a). Thee-phae connecion invee Neual poin poenial vaiaion V MP_nOUT [V] 3 V [V/div] 5[m/div] [V/div] 5[m/div] (b). V-connecion invee Fig.7. Neual poin poenial vaiaion, i can be confimed ha he neual poin poenial vaiaion of he V-connecion BTB yem i highe han ha of he hee-phae connecion BTB yem he conduced emiion of he V-connecion BTB yem become highe han ha of he hee-phae connecion BTB yem. In he fuue, in ode o educe he conduced emiion of he V-connecion BTB yem, he wiching paen will be analyzed. Baed on hi, a new conol mehod which can educe he conduced emiion by uppeing he commonmode volage in he V-connecion BTB yem will be deived. REFERENCES [] E. Demikulu, e al., Volage Conol of A Fou-Leg Invee Baed Thee-Phae UPS by Mean of Saionay Fame Reonan File Bank, IEMDC 27, pp (27) [2] J. G. Tacy and H. E. Pfize, Achieving High Efficiency in a Double Conveion Tanfomele UPS, IECON 25, pp (25) [3] A. Sao, e al., An Inveigaion of Caie Compaion Mehod fo V- connecion and hee-level V-connecion Powe Convee, SPC-93, IEA-2, MD-25, p.6-66 (2) (in Japanee) [4] A. Sao, e al., Opeaing Chaaceiic of hee-level V-connecion PWM Recifie-Invee, IEEJ annual meeing, 4-78 (2) (in Japanee). [5] S. Nagai, e al., Two-Swich Auxiliay Reonan DC Link Snubbe- Aied Thee-Phae V-Connecion ZVS-PWM Invee wih Two Quadan ZVS-PWM Choppe, PESC 24, pp (24) Leakage cuen [dbma] Leakage cuen [dbma] Conduced emiion [dbmv] 7 3 file Heaink 55 khz.8 MHz.6 MHz 5 MHz 9 MHz file cuen Fequency [MHz] (a) Thee-level hee-phae-connecion BTB yem 7 file 3 Heaink.4 MHz 2. MHz 6.7 MHz 9.5 MHz file Fequency [MHz] 6 (b) Thee-level V-connecion BTB yem Fig.8. Hamonic analyi of CM leakage cuen Thee-phae connecion V-connecion 55 khz.4 MHz.6 MHz 5 MHz 6.7 MHz Fequency [MHz] Fig.9. Meauemen eul of conduced emiion in boh yem, conduced emiion of he V-connecion i highe han ha of he hee-phae connecion in all fequencie [6] S. Omaa and T. Shimizu, Sudy on an Accuae Calculaion of he Conduced EMI Noie of he Powe Convee, 24 Inenaional Powe Eleconic Confeence, No. 2P4-8, pp [7] H. Bihnoi, e al., Analyi of EMI Teminal Modeling of Swiched Powe Convee, IEEE Tan. Powe Eleconic, Vol.27, No.9, pp (22) [8] H. Akagi and T. Shimizu, Aenuaion of Conduced EMI Emiion Fom an Invee-Diven Moo, IEEE Tan. on Powe Eleconic, Vol.23, No., pp (28) [9] F. Coa, e al., Influence of he dive cicui in he geneaion and anmiion of EMI in a powe convee: effec on i elecomagneic ucepibiliy, Euopean Powe Eleconic Jounal, Vol. 5, No., pp (995) [] H. Zhu, e al., Analyi of Conduced EMI Emiion fom PWM Invee Baed on Empiical Model and Compaaive Expeimen, PESC 99, vol.2, pp (999) [] S. Ogaawaa and H. Akagi, Suppeion of common-mode volage in a PWM ecifie/invee yem, Thiy-Sixh IAS Annual Meeing Confeence Recod of he 2 IEEE, Vol.3, p (2) [2] T. Aaki, el al., Expeimenal Veificaion of an File Ued fo PWM Invee wih Wide Band-Gap Device, 24 Inenaional Powe Eleconic Confeence, No. 2J3-4, pp