ứng dụng bộ điều khiển mờ PID trong hệ ổn định nhiệt độ lò nung

Tap chi khoa hgc Tn^ng Dai hgc Quy Nhdn - Sd2, Tqp IX nam 2015 ifNG DUNG BO DIEU KHIEN M6 PID TRONG Hfe ON DINH NHIET DQ LO NUNG DINH CONG THONG=, TR^dNG MINH TAN^ DAT VAN DE Vdi CETU tnic dcJn gian, kha nang dieu khidn hieu qua va pham vi u'ng dung r6ng nen bp dieu khien vi tich ph^n ti le, goi tat la bp dieu khien PID (Proportional Integral Derivative) du'pc su* dung phd biS'n cong nghiep Tuy nhien, thiet kS' cac he so' ciia hp dieu khien PID chi difpc tinh toan cho mpt chS' dp lam viec cu the cua he thong, nhi^u tnfdng hpp no to kem hieu qua mo hinh doi ttfpng thieu chinh xac [1], [6], dieu se dSn tdi dap itng dac tinh dpng hpc va tinh ben vUng cua he thong thifdng khong dat yeu cau ve lifcfiig qua dieu chinh, sai so' xac l$p, Vdi cac ky thuat dieu khien thong minh hien nay, logic md dufpc iJng dung cong nhilu linh vu'c vdi vai trd cua mpt bp dieu khien hoac giam sat [2], [4], [5], nguyen tac tac dpng chi c t n dUa tren si^ bien doi dap u'ng cua he thong ma khong cin biet tnfdc phifdng tnnh toan cua dd'i tifdng, von kho dat dtfdc mdt each chinh xac thifc te Tuy nhien, viec siJ dung dpc lap cac bo dieu khien khac thifdng khdng mang lai hieu qua cao dieu khien Chang ban, s& dung bp dieu khien PID, dap d'ng vdi thdi gian qua dd nhd nhifng lifpng qua d i i u chinh va sai sd' xac lap ldn, dieu khong td't hd dn dinh nhiet dp, cdn siJf dung bp d i i u khien md, dap u'ng ch$m hdn nhifng hau nhif khdng cd liJcJig qua dieu chinh ciing nhif sai sd xac lap [3] Va'n d l dat lam the nao de kd't hdp chiing lai vdi nhau, tao dac tinh ddng hoc td't nhat B i i bao gidi thieu ve bp d i i u khien lai giifa bd dieu khien md va bp dieu khien PID, bd d i i u khien PID d vdng giO" vai trd la bp d i i u khien chinh d l k i l m soat dd'i tifcfng va mpt bp d i i u khien md d vdng ngoai d^ bii tham sd' hp dieu k h i l n PID xung quanh gia tri thu difdc tijf phifdng phap thtfc nghiem Ziegler-Nichols, gpi chung la bp d i i u khien md PID Ket qua cho thay dap d'ng vdi thdi gian tang va thdi gian xac lap hdp 1^, lifdng qua d i i u chinh va sai sd xac lap gan nhif difdc triet tieu 74 BINH CONG THONG-, TRlftjNO MINH TAN> PHLfCiNG PHAP NGHIEN CLTU DIEU KHIEN NHIET DO LO NUNG 2.1 Ham truyen 16 niing va cam bi^'n nhi^t dO [3] - Ham truyen m6 ta 16 nung bang mpt khau quan tinh bac nha't co t r i : W(s) = — - " Ts-H 6,52e " (1) ISOs-H - Ham t m y i n cam bien nhi$t d6 difcfc coi la mpt khau ti le vdi h8 so: , lOF = O,0067(P/°C) 1500"C (2) 2.2 Dieu khiln nhiet dfi 16 mmg bang bo dieii khis'n PID Bp dieu khien PID vdi cau tnic ddn gian va tin cay nSn diTdc d6ng bien cac he di^u khien tU dpng phuc vu san xu4't Hani truyen cua b6 dieu khiln PID la: u(t) = K, de(J) e(t)-^~le(t)dt + T^ hay! G„^(s) = Kp dt '- + K„ (3) V d i e W l a tin hieu vao, MW 14 tin hi6u ra; Jf^, X,, Jf^la c a c h e sd'ty 16, tich phan, d a o ham T, la hang so tich phan, r „ la hang s6' vi phSn Ro rang, u(t) phu thupc vao cac tham s6'A"^ T,, T^ ciia bd dieu khien PID va dd chat Itfdng tin hieu cua hS thd'ng cung phu thupc theo Stir dung bo dieu khiln PI va xac dinh cac tham so' bang phufdng phap thiJ nhat Ziegler-Nichols: K, = 0,83 va K, = 0,01 Md Unh dieu khien nhiet dp lo nung bang bp dieu khien PID t h i hien nhiT Hinh H-(;>->IB—