Highly-Efficient Multi-Coil Wireless Power Transfer (WPT)

Transcription

1 Hghly-Effcent Mult-Col Wreless Power Transfer WPT Mehd Kan May 3, 04 GT-Boncs ab, School of Electrcal and Computer Engneerng Georga Insttute of Technology, Atlanta, GA

2 WPT Applcatons Chargng moble electroncs Implantable Medcal Devces IMDs RFID Chargng electrc cars

3 Coupled-mode Magnetc Resonance-based Power Transmsson Proposed by physcsts at MIT based on coupled-mode theory CMT An alternatve wreless power-transfer technque usng typcally four cols Goal: Increase the power transfer effcency PTE at large couplng dstances 60-W s transferred from -m away A. Kurs, et. al, Scence

4 Questons? A need for a comprehensve crcut theory for coupled-mode magnetc resonance-based lnks A need for crcut theory based on the reflected-load theory RT for mult-col lnks Are coupled-mode magnetc resonance-based lnks always the optmal choce? A need for a new fgure-of-mert FoM for hgh performance mult-col desgn vs. Resonant-magnetc couplng Inductve couplng 4

5 Calculatng Power Transfer Effcency PTE based on RT Secondary R 3 3 C 3 can be reflected onto the prmary: PTE R R ref R ref Q 3 k3 QQ3 Q3. k3qq3 Q Q R 3 R3 R PTE s hghly dependent on: k 3, Q, and Q 3 3 Q 3 = Q 3 Q / Q 3 +Q Q = R / ω 0 Rref k3 / 3 Q3 R3 R k30q3 C ref 3 / C3 / k3 / 0 k 3 R.R. Harrson, ISCAS 007 M.W. Baker and R. Sarpeshkar, TBoCAS

6 Maxmzng PTE n -Col nk k3qq3 Q3 col. k3qq3 Q For a gven set of Q, Q 3 and k 3 values, there s an optmal load, R,PTE, whch can maxmze the PTE at that partcular arrangement, such as the couplng dstance. R,PTE 0 3Q,PTE Q, PTE PTE s hghly dependent on R R s often predefned by the applcaton Q3 k Q Q Matchng crcuts Multple cols 3 3 / Impedance Transformaton M. Kan and M. Ghovanloo, TBCAS 0 6

7 PTE and Delvered Power PD n Multcol Inductve nks based on RT In an m-col lnk wth neglgble couplng between nonneghborng cols R ref from + th col to the th col: oaded Q of the th col: Q 0 PTE between th and + th cols: m-col lnk PTE: PD: P, mcol V R s mcol k m Q Q, m R ref k,, 0Q / R R Q / Q mcol ref, R / R R, ref, ref, Parallel load: Seres load: Qm = R /0m Q m = 0 m / R Four-col lnk m = 4 M. Kan and M. Ghovanloo, TBCAS 0 7

8 8 PTE n Mult-col Inductve nks based on CMT In m-capactvely loaded resonators: Four-col lnk m = 4 Resonance wdth: t F t a jk t a j dt t da S, t a jk t a j dt t da m m m m m m,, t a jk t a jk t a j dt t da m m m S col m A A P P t j e A t a 0 A P Q / 0 Couplng rate: /, 0, k K PTE from CMT s dentcal to the one from RT! M. Kan and M. Ghovanloo, TCAS-I 0

9 Resonant Magnetc Couplng vs. Inductve Couplng Transent Md-range hgh-q condton Short-range low-q condton CMT transent response s accurate when cols couplng s weak and cols qualty factor s very hgh! M. Kan and M. Ghovanloo, TCAS-I 0 9

10 3-Col Inductve nk k3qq3 k34q3q4 Q4 3 col [ k3qq3 k34q3q4 k34q3q4 ] Q 3-4 nductve lnk provdes desgners wth a DoF M 34 to adjust the reflected load on to 3 to be the optmal value: R,PTE oosely coupled - 3 lnk s desgned for optmal R,PTE Inductve lnk optmzaton s decoupled from R 3-4 nductve lnk PTE s hgh as ther couplng dstance s small 3 R,PTE 0 3Q,PTE Q, PTE / k3qq3 Q 4 3 M. Kan and M. Ghovanloo, TBCAS 0 0

11 Maxmzng PTE n the 3-Col nk By changng k 34 and R ref,3, the 3-col PTE can be kept at maxmum for a wde range of R. A -col lnk does not provde ths flexblty, and PTE maxmzes only for a specfc R value. M. Kan and M. Ghovanloo, TBCAS 0

12 4-Col Inductve nk 4col [ k Q Q. kqq k3qq3 k34q3q4 Q4 k34q3q4 k3qq3 ].[ k3qq3 k34q3q4 ] Q 4-Col lnk adds an addtonal DoF for mpedance matchng on the source sde If k s large, the reflected load onto ncreases dramatcally, whch helps maxmze the PTE at the cost of reducng PD M. Kan and M. Ghovanloo, TBCAS 0

13 PTE and PD n 3-Col nk Maxmzng PTE should not be at the cost of decreasng PD Vs k3qq 3 k34q3q 4 Q4 P,3col R k3qq 3 k34q3q 4 Q The optmal desgn maxmzes both PTE and PD k k 3, PD 34, PD k34q3q QQ3 4 k3qq Q3Q4 3 / / M. Kan and M. Ghovanloo, TBCAS 0 3

14 PTE and PD n 4-Col nk If k s large enough, 4- col can tolerate varatons n col separaton k 3 and mantan a large PTE arge k reduces the avalable power from the source Small overlap between hgh PTE and PD areas M. Kan and M. Ghovanloo, TBCAS 0 4

15 3-Col vs. 4-Col nk Measurements V s = V 3-col lnk PD = 60 mw 4-col lnk PD = 4.4 mw M. Kan and M. Ghovanloo, TBCAS 0 5

16 Resonant-Magnetc Couplng vs. Inductve Couplng PTE Four-col lnk measurement setup. Three and two-col lnks used smlar cols except and 4, respectvely. Calculated PTEs were smlar from CMT and RT and matched very well wth measurements! M. Kan and M. Ghovanloo, TCAS-I 0 6

17 A New Fgure of Mert FoM for Inductve Power Transmsson Conventonal desgn merts are ether PTE or PD How to balance PTE and PD? How to choose between -, 3-, and 4-col lnks? FoM n mcol V P s, mcol FoM effect on PTE and PD drop: n: PTE weght, whch depends on the applcaton P oss, oss max P max,max P FoM P,max n, FoM, n n, max P,max, P FoM, : PTE and PD are maxmzed FoM : FoM s maxmzed M. Kan and M. Ghovanloo, TIE

18 PTE vs. PD oss based on FoM for -, 3-, and 4-col nks FoM n mcol P, mcol n = 0 FoM ~ PD V n s FoM ~ PTE n = results n smlar PTE and PD drops = 5% M. Kan and M. Ghovanloo, TIE

19 Optmal -col nk for IMDs based on FoM -col nk for IMDs Rx col da. = 0 mm V s = V R s = 0.5 Ω R = 00 Ω f 0 = 3.56 MHz d 3 = 0 mm At d 3 = 0 mm, FoM-optmzed lnk provdes 47% more PTE than the PD-optmzed lnk and 6 tmes larger PD than the PTE-optmzed lnk. M. Kan and M. Ghovanloo, TIE

20 Comparng - 3- & 4-Col nks for IMDs At d 3 = 0 mm, 4-col lnk provdes 4.9% more PTE and tmes less PD than an equvalent 3-col. At d 3 = 0 mm, PTE dfference s 7.7%, whle PTE of 3-col s 9 tmes larger than an equvalent 4-col For large R s, 4-col s optmal An FoM ncludng both PTE and PD s needed to dfferentate between -,3-, and 4-col lnks! M. Kan and M. Ghovanloo, TIE

21 Optmal Mult-col nk for Chargng Handheld Moble Devces based on FoM The 4-col lnk has superor FoM at d 3 = 0 cm at the cost of much lower PTE, and consequently the FoM, at shorter couplng dstances. Rx col da. = 4 cm, R s = 0.5 Ω, R = 5 Ω, f 0 = 3.56 MHz, d 3 = 0 cm M. Kan and M. Ghovanloo, TIE 03

22 Optmal Mult-col nk based on FoM Strong couplng k Weak couplng k -Col nk 3-Col nk 4-Col nk arge PD small R s Small PD large R s Couplng varatons & small R s Couplng varatons & large R s M. Kan and M. Ghovanloo, TIE 03