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1 EEE PEDS 07, Honolulu, USA 5 December 07 olage Source nverer wih Phase Shif onrol for Wireless E harger Naapong Hachavanich, Mongkol Konghirun an Anawach Saengswang 3 Deparmen of Elecrical Engineering Faculy of Engineering, King Mongku s Universiy of Technology Thonburi Bangkok, Thailan hachavanich@gmail.com, mongkol.kon@kmu.ac.h, anawach.san@kmu.ac.h 3 Absrac - n he wireless power ransfer (WPT) sysem for E charger, he resonan inverer is mainly use as power converer. The primary circui can reuce he inverer curren while amplifying he primary curren by he raio of b/. This paper presens he resonan inverer. The effecs of non-linear loa an high orer circui are focuse by consiering he fruency response an iminishe by aing series capacior wih seconary pa. The high orer componen eliminaion is valiae by he fruency response. The swiching paerns can be moifie o conrol inverer curren which affecs he oupu power. The phase shif conrol is selece in his paper which is he symmerical volage propery. The blocking capacior is no neee. The moifying square wave volage will affece o he phase beween volage an curren of inverer. The phase proecion is use for proec non S coniion. Finally, he propose opology is valiae by he experimen. Keywors Wireless power ransfer; esonan inverer;. NTODUTON During he pas few years, he wireless charger has gaine aenion in supplying power o elecric vehicles (Es). The main avanage of wireless charger over convenional conucive charger is river s convenience []. The wireless charger employs he principle of wireless power ransfer (WPT) o ransfer elecrical power from primary pa o seconary pa wihou physical conac. The srucure of WPT sysem can be shown in Figure. The recifier sage convers single phase A o D volage. The main conroller is on he primary sie. The resonan power converer (P) is use o generae sinusoial curren. The P feaures zero volage swiching (S), zero curren swiching (S), high fruency operaion, small size, an low elecromagneic inerference (EM) []. The primary pa is normally compensae in orer o minimize he A raing of power supply [3]. A large sinusoial curren in he F (i.e., 3 khz o 30 khz) is supplie hrough he primary pa ( ) o generae he magneic flux inuce o he seconary pa ( ). The primary compensaion use in he resonan circui is o amplify he primary pa curren ( ), creaing he greaer magneic flux. ircui boars on he seconary sie are insalle on-boar in he vehicle. The seconary sie consiss of parallel ecoupling circui incluing he seconary pa an capacior. The recifier is connece wih non-linear loa (power swiching converer) a he en of parallel ecoupling circui. This seconary sie is conrolle by he D/D converer o ajus he seconary qualiy facor ( ) an regulae he baery volage [4]. The series an parallel ypes are wo basic resonan circuis wih simple srucure. The avanages of series primary resonan circui are such as supply sable volage, an blocking of c componen from inpu volage by series capacior. On he oher han, he large high-fruency curren hrough series capacior will ge he high capacior volage. The parallel primary circui offers no loa regulaion an supply sable curren bu lacking of c componen blocking. n he seconary sie, he series seconary resonan circui supplies he sable volage an reflec only real par of impeance o he primary sie. The parallel seconary resonan circui supplies he sable curren which is suiable for baery charger This circui allows he reflecion of boh real an imaginary pars of impeance o he primary sie. The resonan fruency woul be change when loa is varie. n pracice, he loa on he seconary sie canno moel as pure resisance an he non linear loa, increasing he sysem s orer. Power supply ecifier nverer Fig.. The srucure of WPT sysem To combine he avanages of boh simple resonan circuis, he - resonan circui is presene. The resonan circui use in he primary sie. The aiional series inucor ( b) is connece beween he volage source an parallel primary resonan circui in orer o regulae he inpu curren supply o primary pa. The resonan circui is implemene in he seconary sie. The seconary series capacior (,s) reuces he high orer componens ue o he non linear loa, an he seconary series inucor ( ) filering he inpu recifier curren in he seconary sie. M b Non linear loa Off - boar On - boar /7/$ EEE 97

2 . SYSTEM ONFGUATON B. resonan inverer esign A. Power pas esign The oupu power of an WPT sysem can be calculae by he prouc of open circui volage ( oc), shor circui curren ( sc) an he qualiy facor of he receiver pa as expresse in uaion () [3]. S s s D inv b i b Y p P S ( M / ) () ou u oc sc where, S u is he uncompensae power (A) ; is he angular fruency (ra/sec); is he primary curren (A) ; M is muual inucance (H) ; is he esigne loa qualiy facor. eferring o his uaion, he oupu power is primarily compose of he resonan inverer erm (ω ), an coupling erm (M / ). These wo erms are epenen on he srucure of power pas an qualiy facor () of he seconary sie loa. To achieve he high efficiency, i is necessary ha boh power pas have he highes coupling erm (M / ). The power pa consiss of copper wining an ferrie se. The copper wining is compose of 00 srans of AWG3 iz wire. The circular pa is esigne o cope wih 3,800 A a a verical isance of 00 mm. The power pa layou is illusrae in Fig. The ferrie se is esigne for guiing he magneic flux an improving power ransfer capabiliy. Each long ferrie leg is mae of hree cores wih a imension of mm. An each shor ferrie is mae of wo cores wih same imension. The copper wining iameer () is approximaely 57% of he pa iameer (D) an a hole iameer (A) is approximaely % of he power pa iameer [5]. The propose power pas in his paper are epice in Fig. 3. All imension in mm. A : 0 B : 340 : 50 D : 9 8 Turns of iz wire iz coil wih 48mm. Fig.. Power pas layou. S Fig. 4. resonan inverer S 4 Accoring o he resonan inverer uivalen circui, he uivalen inucance ( ) is he combinaion of self inucance of primary pa ( ) an he reflece inucance from he seconary sie. The uivalen resisance ( ) is he combinaion of inernal resisance of primary pa an he reflece resisance from he seconary sie. The expression of reflece impeance is expresse as follows. M r () Where is oal impeance of seconary sie. As seen in Fig. 4, he parallel amiance (Y p) is shown in uaion (3) Y p j j The primary capacior ( ) is une basing on he zero imaginary par of Y p, an hen is expresse in uaion (4) ( 0 ) The inpu impeance ( i) of resonan loa is expresse as follows. oal j j j ( j) j 3 b b b Accoring o he inpu impeance of resonan loa, he power angle ( ) can be foun as follows (3) (4) (5) ( ) arg{ ( j )} arcan( ) 0 (6) oal b 0 0 The resonan loa has wo resonan fruencies as follows. Fig. 3. Power pas layou. f (7) ani resonan 98

3 f resonan b (8) b The primary series inucor ( b) is use for regulaing he inverer curren ( b) supplying o he parallel resonan ank. For he properies of parallel resonan circui, a he resonan fruency, he primary pa curren ( ) is amplifie epening on α (he raio of b / ). The primary curren which is a funcion of inverer curren is shown in uaion (9) b cos (9) Or (3), s (4) 3 The oal seconary sie qualiy facor () can be escribe as a prouc of an volage qualiy facor ( v) [6]. The v can be efine as (5). Seconary sie uivalen circui Seconary sie uivalen circui moifie from seconary compensaion circui is shown in Fig. 5. The seconary uivalen circui consiss of compensaion circui connece wih ioe brige recifier. The uivalen resisance of recifier wih capacior oupu is expresse as uaion (0) Where X e (6) X (7),s 8 e (0) The seconary compensaion circui is moifie from parallel compensaion circui by aing,s an. The is use for filering he recifier inpu curren. The parallel impeance of seconary sie (,p) is shown in uaion (), p jm ( ) e e ( ) j e r jm,s, p c () The oal seconary impeance ( ) is expresse in uaion (8). Where, p j( X X X ) (8), p, p, s ( ) e, X e, p e ( ) (9) D. Phase shif conrol The phase shif conrol or symmeric volage cancellaion (S) [7] is use o conrol he oupu inverer curren by ajusing he phase shif angle (σ) of gae rive signals. Then, he inverer oupu volage is formulae as follows. Fig. 5. Seconary sie uivalen circui The value of seconary capacior ( ) is expresse in uaion () ( 0) e () n Fig. 6, he aiional capacior is ae in series wih seconary inucance. This allows he maximum loa curren by reucing he reacance. This series capacior wih seconary inucor woul reflec only real par o he primary sie. The series resonan circui gives he amplifie curren corresponing o he erm of curren qualiy facor ( ) The value of is given by [6] inv Fruency comman ero - cross O inv XO c sin ω/ OS Fig. 6. Phase shif conrol implemenaion S ω PF Phase shif angle Phase proecion XO omp. omp. conrol nhibi inverer (0) S S S 4 99

4 Gain (B) Phase (Degree) esonan S Phase shif angle ou Ani -esonan esonan Non linear loa on seconary sie - - Fig. 7. Phase shif conrol riving signals The oupu power of he sysem (P ou) is shown in uaion (). learly, he power elivere o he seconary sie is epenen on α an σ. The oupu power is maximum when σ uals o 80 egree. P ou 4 cos c sin () Fig. 6 shows he phase shif conrol implemenaion. olage conrol oscillaor (O) generaes he pulse signal wih x of fruency (n his case, he swiching fruency is fixe an higher han he resonan fruency). The phase shif angle signal is generae by comparison beween he conrol signal an he ramp signal. Then, he exclusive or (XO) is use o creae he phase shife gae rive signals. The oupu inverer volage is in phase wih inverer riving signal S. Therefore, he gae signal can be use insea of inverer oupu volage for phase eecion. The oupu inverer curren signal is compare wih he volage signal o eec phase ifference. This allows he operaion on he esire fruency range of he S moe. f he phase feeback becomes ou of he preeermine limis, he inhibi signal is acivae o force he riving signals o sop. The phase shif conrol riving signal is shown in Fig. 7. EXPEMENTA ESUTS Simulae fruency response an experimens are use o valiae he propose sysem. A sysem parameer is shown in Table. The verical isance beween boh power pas is se a 5 cm. By using he parameers in Table, he simulae fruency response can be illusrae in Fig. 9 TABE EXPEMENTA PAAMETES Parameer alue Parameer alue 300 µh 300 µh b 60 µh 3.8 nf 9 nf,s 98 nf 48.7 µh 5 Ω c 80 M 9 µh f s 9.3 khz c 300 µf Non linear loa on seconary sie Ani -esonan Fruency (khz) Fig. 9. The fruency response of inverer curren. The simulae fruency response in Fig. 9 shows he inverer curren response comparison beween wo ifferen opologies. The compensaion moifie from P ( parallel seconary compensaion) by aing series wih recifier. The firs wor sans for circui configuraion on primary sie an he secon wor sans for circui configuraion on he seconary sie. The uivalen circui of - can form ino high orer circui. The non linear loa on he seconary sie can be moelle as highly inucive loa. The is use for filering he recifier inpu s curren. eferring o he fruency response, he response of inverer curren compensaion can be separae ino wo pars. The firs par is a lower fruency because of he compensaion in primary circui. An he secon par is a higher fruency as a resul of compensaion in seconary combine wih recifier loa. The effec of high orer circui sill appears a he primary sie. However, highly inucive loa series wih sill resuls in high orer erm an reflecs he imaginary par o he primary sie when loa is change. To eliminae he resul of high orer circui, he compensaion is use in he seconary sie. The,s is ae in series wih seconary pa. One propery of series resonan is reflece only real impeance o he primary sie. eferring o response, he inverer curren gain a high fruency (resul of recifier loa) is iminishe ue o a resul of series resonan. Aing,s can reuce he effec of non linear loa on seconary sie an loa changing. Fig. 0 hrough show he experimenal resuls uring operaion uner ifferen phase shif angles. The inverer shoul be operae over resonan fruency. The inverer is operae a 9.3 khz where he resonan fruency is 9 khz. The experimenal resul in Fig. 9 is performe uner he maximum phase shif angle coniion. n his figure, he MS value of b is 3.8 A while he MS value of is 6. A. The D loa volage is 4 an he oupu power is 0 W. Nex, he experimenal resul in Fig. 0 is performe uner 0 of phase shif angle. The MS value of inv is reuce o 60 an he oupu power is 9 W. The MS value of b an is 3.3A an 5.4 A, respecively. The D loa volage 37. Then, he experimenal resul in Fig. is one uner 90 phase shif angle. This case is operae in he bounary 300

5 S coniion. f increasing he phase shif angle, he non S coniion woul be occurre uring urn-on swiching. Operaion uner non-s coniion leas o high volage sress uring swiching commuaion. eferring o he experimenal resuls, he b is less han because of he α value. For he bes operaing coniion, he b shoul be ual o (α = ) incurring he highes power coniion. n his paper, he riving signals can be moifie for regulaing he inverer curren. n his case, he phase of riving signal of each branch is shife. The oupu power is irecly conrolle by ajusmen of he phase shif angle. inv b 80. ONUSON This paper presens he resonan inverer wih phase shif conrol. The recifier loa in he seconary sie sill resuls in high orer circui an reflecs he imaginary par o he primary sie when loa is change. The compensaion in seconary sie can reuce he orer of he sysem which affecs he non linear loa. The primary compensaion makes large primary pa curren wih low inverer curren use along wih he volage source inverer. The ajusmen of phase shif angle of riving signals on each branch is inclue in orer o conrol he inverer curren for power ransfer. To operae in he S coniion, he inverer mus be proece when he phase shif angle becomes ou of limi. AKNOWEDGMENT The financial suppor from he esearch an esearchers for nusries () Ph.D program, he Thailan esearch Fun (TF) is acknowlege. Fig. 0. Top o boom race, inv, 80 inv b Fig.. Top o boom race, inv, 0 inv 0 90 EFEENES [] A. Khaligh an S. Dusmez, "omprehensive Topological Analysis of onucive an nucive harging Soluions for Plug-n Elecric ehicles," EEE Transacion on ehicular Technology, vol. 6, pp , Oc. 0. [] M. T. Oueiro, G. Buja an D. zarkowski, "esonan power converers: An Overview wih Muliple Elemens in he esonan Tank Nework," EEE nusrial Elecronics Magazine, vol. 0, no., pp. - 45, Jun. 06. [3] J. Boy, G. ovic an A. Green, "Sabiliy an conrol of inucively couple power ransfer sysems," EE Proceeings - Elecric Power Applicaions, vol. 47, pp , Jan [4] G. ovic, J. T. Boys, A. Tam an J.-H. Peng, "Self uning pick-ups for inucive power ransfer," in Power Elecronics Specialiss onference, 008. PES 008, hoes, Greece, 5-9 June 008. [5] M. Buhia, G. A. ovic an J. T. Boys, "Design an Opimizaion of ircular Magneic Srucures for umpe nucive Power Transfer Sysems," EEE Transacion on Power Elecronics, vol. 6, no., pp , Nov. 0. [6] N. A. Keeling, G. A. ovic an J. T. Boys, "A Uniy-Power-Facor PT Pickup for High-Power Applicaions," EEE Transacions on nusrial Elecronics, vol. 57, no., pp , Feb. 00. [7] M. Borage, S. Tiwari an S. Koaiah, "Analysis an Design of an -T esonan onverer as a onsan-urren Power Supply," EEE Transacions on nusrial Elecronics, vol. 5, no. 6, pp , Dec b Fig.. Top o boom race, inv, 90 30