Tap chi Khoa hoc va Cong nghe 102 (2014) 006-011 2 ' la ham trl &cn\ vi (ham tre sau mot chu ky lay
mau),
AD( la bi^n thien ciia khoang dan ciia van FET trong mot chu ky dong cat tai thai diem lay mau thii k.
Hinh 3. So do kh6i bp dieu khien logic ma dung de xac dinh thay doi ciia khoang dan ciia van FET trong mot chu ky dong cat.
Khoi m o hoa (Fuzzification) lam nhiem vy chuyen cac dau vao (e^ va de^.) va ra ( A D , ) a dang gia tri ro thanh cac ham lien thugc co dang hinh tam giac va hinh thang nhir hinh.4 Thong thuong, trong thuc te cac ham lien thupc hinh thang va tam giac dirpc chpn vai ly do cac ham lien thupc dang nay d§ thuc thi va lam don gian hoa dang ke qua trinh suy luan mir
Dpng CO suy lu£in (Inference Engine) bao gom 25 quy tac quan he giija 2 dau vao (e^ va de^.) va dau ra (AD,,) duac trinh bay nhir tren bang. I.
Bang I. Bang cac quy tJc
..
PB PS ZZ NS NB
de.
NB ZZ NS NS NB NB
NS PS ZZ NS NS NB
ZZ PS PS ZZ NS NS
PS PB PS PS ZZ NS
PB PB PB PS PS ZZ Trong bang, 1, y nghTa ciia cac chii viet tat tieng Anh nhu sau:
NB: Negative Big (Am nhilu) NS, Negative Small (Am it) ZZ: Zero (Khong am va khong duong) PS: Positive Small (DuoTig it) PB: Positive Big (Ducmg nhi6u)
Tai mot thai diem nhat dinh, theo bang, 1 ta co mot so cac quy t5c mo duac trinh bay nhu sau:
NEU e, la PB VA de, la NB THI AD^ la ZZ NEU e, la PS VA de^ la NB THI AD, la NS NEU e, la ZZ VA de, l a N B T H I AD, l a N S
NEU e, la NS VA de, la NB Tffl AD, la NB NEU e, la NB VA de, la NB THI AD, la NB
Cuoi cimg cac tap m a dau ra sg dupe lam ro hoa bang phuong phap trong tam (Centre of Area/COA) nhir sau:
I/'('(0)"('
I/'(-(0)
(1)T r o n g p h u o n g trinh (1) ta c o :
xii) la gia trj thii / ciia khoang bien thifin ciia h a m lien thupc d a u ra A D , ,
/ i ( x ( / ) ) l a gia trj h a m Hen t h u o c ciia b i l n AD, l i n g v o i x{i),
•^coA '^ S'^ tti ciia bien thien dau ra AD, sau khi l a m ro hoa.
!, mm ,0 04 -0.02 0 0.02 0.04 e, max
I -SO 40 0 40 80 de,mxi (b)
MF NB NS ZZ PS PB
AD, min .0.04 -0.02 0.02 0,04 AD, max (c)
Hinh 4. Cac ham lien thupc: (a) Cac ham hen thupc ciia bien e,, (b) Cac ham lien thupc ciia bien t/e,, (c) Cac ham Hen thupc cua bien ADk.
3 . Tbirc ngtiiSm
He th6ng nap kc quy su dung nang lirpTig mat trcri duac trinh bay nhu tren hinh 5, bao gom:
1- Mot bp thu thap dQ heu 14 bit NI USB-6009 ciia hang (National Instruments/NI) [8] vdi 2 dau vao tuong tir de do dien ap va dong dien ra ciia bang
Tap chi Khoa hoc va Cong ngh$ 102 (2014) 006-011 pin mat troi, 1 dau ra tucmg tir dtia den chan dau
vao tuong tir ciia vi dieu khien dsPIC.
2- Mach dpng luc: Mach nang ap tir mot chieu sang mpt chieu (Boost DC/DC Converter) co cac thong so nhir sau:
- Cupn cam L = 50mH - T u d i e n C = lmF - Khoa chuyen mach FET - Diot chuyen mach D
3- Bang pin mat troi Model SL120CE-24M [9]
4- Mot laptop cai phan LabVIEW dung de do luong va dieu khien.
5- Tai la 5c quy 24V dupe noi vai dau ra ciia mach nang ap.
Mach dieu khien qua trinh dong cat cua khoa FET sii dung vi dieu khien Microchip dsPlC33fjl2mc202 vai dau vao la tin hieu tucmg tir thay doi tir 0 den 3,3V va dau ra la tin hieu diSu biSn dp rpng xung (Pulse Width Modulation/PWM) tan so 50kHz.
Hinh 5. He thong thuc nghiem nap ac quy sii dung nSng luong mat troi vai MPPT.
Toan bo thuat toan dieu khien dupe viet bang ngon ngir C, Phan mem Pelles C [10] dupe su dyng de bien dich ma ngu6n C ra cac file a dinh dang thu vien lien ket dpng (Dynamic Link Library/DLL), Cac file DLL sau do se duac gpi ra trong moi tnrang LabVIEW. Hinh 6 la giao dien nguoi sir dung duac xay dung bang phan mem LabVIEW cho phuong phap P&O va cho phuong phap dua tren logic ma.
Giao dien bao gom cac phan tit do luong ao (Virtual InstrumentsWI) dung de hien thi dien ap cua bang pin mat trai, dong dien cua bang pin mat trai va cong suat ciia bang pin mat troi, Ben canh do, giao dien con hien ihi cac thong so sau:
dD; bien thien khoang dan cua khoa FET trong mpt chu ky dong cat.
D k _ l : thoi gian dan trong mot chu ky dong cat cua van FET tai thai diem lay mau thii k-\.
Dk: thai gian dan trong mpt chu ky dong cat ciia van FET tai thai diem lay mSu thii k . Tin hieu dieu khien (control signal) dua den dau vao analog cua vi dieu khien dsPIC.
Do thi bien thien theo thai gian ciia cong su^t Edn nhat bang pin mat troi.
Cac gia tri dien ap, dong dien va cong suat dupe liru lai o dang file "txt" de dupe ve lai su dung phan mem Matiab. Hinh,7 la thay doi ciia cong suat Ion nhat cua bang pin mat troi iheo thai gian.
.^"-j*.!
\-
Hinh 6. Giao dien nguai sir dung xay dung I p h k mSm LabVIEW cho MPPT.
20 25
' " " " I ' l Tim8[s)
(a) Phuang phap P&O (b) phuong phap dua tren logic mo Hinh 7. Thay doi cong suat lan nhat ciia bang pm mat trai theo thoi gian
9
Tap chi Khoa h^c v^ Cong nghf 102 (2014) 006-011
5 10 15 20 25 30 35 40 15 £0
•nmels)
(b) Phuang phap dua tren logic met Hinh 8. Thay doi ciia dien ap ra cila bang pin mat trai theo th6i gian
Fki££y l o ^ method
(a) Phuang phap P&O (b) Phuong phap dua tren logic mo Hinh 9. Thay doi cua dong dien ra ciia bang pin mlit trai theo thoi gian Theo hinh 7 ta thay chat lupng dong ciia h^:
thoi gian qua d6 va dp qua dieu chinh cua phuang phap logic m a nho hen phuang phap P&O.
Cu the de dat duac cong suat lan nhat phuang phap P&O mat gan 10 giay trong khi phuong phap dua tren logic ma chi mat 5 giay de dat duac cong suat lan nhat. Chat lupng tTnh ciia he: phuang phap dua tren logic ma CO sai so xac lap nho hon phuong phap P&O.
Hinh 8 va hinh 9 lan lucrt la thay 361 cua dien ap va dong dien dau ra ciia bang pin mat trai img vai cong suat Ian nhat theo thoi gian, Phuong phap dua tren logic m a co tan so va bien dp ciia dien ap va f. Ket luan
Bai bao da tong hop cac buoc thuc thi ciia hai phuang phap diing de van hanh he thSng nap ic quy su dung nang lupng mat troi img vai di6m lam viSc cong suat cue dai khi diiu kien moi truong thay d6i:
Phuong phap P&O va phuong phap dua tren logic ma, Cac phirang_ phap nay khong doi hoi phai sii dung cac cam bien moi truong dk do dp birc xa va
nhiet dp tren be mat ciia bang pin mat triri. Phan mem LabVIEW duac sir dyng de do luong va dieu khien cac thong so cua he thong. Phuong phap dua tren logic m o CO nhieu uu diem so voi phuong phap P&O.
Dieu nay cho thay sir dung phuong phap logic mo sg dupe ling dung nhieu hon cho he nang lupng mat troi, nhat la voi cac he cong suat Ion. Day se la cac budc nghien cim tiep theo cua nhom tac gia.
Tai lieu tham khao
[1] S. Bai and B, C, Babu, "Comparative study between P&O and Current Compensation method for MPPT of PV energy system," Conference on Engineering and Systems (SCES). 2012 Students, (2012) I - 6, [2] R, Ramaprabha, B. L, Mathur, and M. Sharanya, "Solar
array modeling and simulation of MPPT using neural network," 2009 International Conference on Control, Automation, Communication and Energy Conservation, (2009) 1-5.
[3] S. Prenmideepreechacham and N. Patanapirom, "Solar- array modelling and maximum power point tracking using neural networks," Power Tech Conference Proceedings. 2003 IEEE Bologna, vol. 2,2003.
Tap chi Khoa hQC v^ Cong ngbe 102 (2014) 006-011 [4] B. K. Bose, "Intelligent control and estimation in power
electronics and drives," IEEE 2. International Conference of Electric Machines and Drives, 1997.
[5] F. H. Martinez S., "Fuzzy logic conUoller for boost converter with active power factor conection," 7th Internanonal Conference on Power Electronics, (2007) 936-940.
[6] M. G Simoes, "Fuzzy Logic Based Intelligent Control of a Variable Speed Cage Machine Wind Generation System," IEEE Transactions on Power Electronics, vol.
12,(1997)87-95.
[7] T. Gupta, "Implementation of a Fuzzy Controller for DC-DC Converters Using an Inexpensive 8-b Microcontroller," IEEE Transactions on Industrial Electronics, vol, 44, (1997) 661 - 669.
[8] http,//sine.ni,com/mps/cds/view/p/lang/en/nid/20l987 [9] http-//nbkxsolar.en made-in-
ch i n a, CO m/p roductA'bunvhlYbtiF/China-Mono-Solar- PaneM 20W-SL120CE-24M-,htnil
[10] http://wv/w, smorgasbordet.com/pel I esc/
