第43卷第6期吉林大學(xué)學(xué)報(bào)(工學(xué)版)Vol, 43 No2013年11月Journal of Jilin University(Engineering and Technology Edition)Nov.2013基于輸入觀測(cè)器的分缸空燃比估計(jì)王萍1,江和耀,范亞南,陳虹(1.吉林大學(xué)通信工程學(xué)院,長(zhǎng)春13002:2.中國(guó)船舶重工集團(tuán)公司第七一三研究所,鄭州450015)摘要:針對(duì)進(jìn)氣道噴射發(fā)動(dòng)機(jī),為了實(shí)現(xiàn)更加精確的空燃比( Air-fuel ratio,AFR)控制,提出了基于輸入觀測(cè)器的分缸空燃比估計(jì)方法。首先建立發(fā)動(dòng)機(jī)的完整油路模型,主要包括燃油傳輸模型、氣體(廢氣)混合過程模型、廢氣傳輸模型和氧傳感器模型,并基于發(fā)動(dòng)機(jī)仿真軟件 enDYNA對(duì)其進(jìn)行校驗(yàn)。然后設(shè)計(jì)了輸入觀測(cè)器來估計(jì)各缸內(nèi)的空燃比,并利用區(qū)域極點(diǎn)配置方法確定觀測(cè)器的増益。最后通過離線仿真和發(fā)動(dòng)機(jī)控制試驗(yàn)臺(tái)架上的實(shí)時(shí)仿真驗(yàn)證了觀測(cè)器的合理性和有效性。關(guān)鍵詞:控制理論;分缸空燃比;油路模型;輸入觀測(cè)器;區(qū)域極點(diǎn)配置中圖分類號(hào):TP273文獻(xiàn)標(biāo)志碼:A文章編號(hào):1671-5497(2013)06-157407DOl:10.7964/ jdxbgxb201306023Individual cylinder air-fuel ratio estimation based on input observerWANG Ping, JIANG He-yao, FAN Ya-nan, CHEN HongCollege of communication engineering, Jilin University, Changchun 130022, China; 2. The 713th Research Instituteof China Shipbuilding Industry Corporation, Zhengzhou 450015, China)Abstract: Based on the input observer, an estimator of individual cylinder Air- Fuel Ratio(AFR) in aSI engine is proposed. The fuel path model, which is constituted by fuel wall-wetting model. exhaustgas mix model, exhaust gas transfer model and universal exhaust gas oxygen(UEGO)sensor model,is established. Then, under the same working condition and with the same input, the developed modelis validated using the precise engine model of enDYNA. Furthermore, an input observer based onregional pole placement is proposed to design an AFR estimator. Finally, the rationality and feasibilitof the proposed observer and AFR estimator are validated by real-time and offline simulations on asimulation platform for automotive engine controKey words: control theory; individual cylinder air-fuel ratio; fuel path model; input-observer; regionalpole placement常用的空燃比控制方法主要有基于經(jīng)典控制智能控制等。然而這些方法沒有考慮實(shí)際的發(fā)理論的PID控制、基于模型的現(xiàn)代控制以及人工動(dòng)機(jī)各個(gè)氣缸以及各個(gè)噴油器之間都會(huì)存在細(xì)微收稿日期:2012-10-19.基金項(xiàng)目:國(guó)家自然科學(xué)基金重點(diǎn)項(xiàng)目(61034001);教育部“長(zhǎng)江學(xué)者和創(chuàng)新團(tuán)隊(duì)發(fā)展計(jì)劃”創(chuàng)新團(tuán)隊(duì)項(xiàng)目(ITR1017作者簡(jiǎn)介:王萍(1982-),女,講師博士,研究方向:預(yù)測(cè)控制,發(fā)動(dòng)機(jī)控制.E-mail:wangping12@jlu.edu.cn通信作者:陳虹(1963-),女教授,博士生導(dǎo)師研究方向:預(yù)測(cè)控制魯棒控制及非線性控制的理論與應(yīng)用E-mail:chen@jlu.edu.cn第6期王萍,等:基于輸入觀測(cè)器的分缸空燃比估計(jì)·1575·差別,使得各缸內(nèi)空燃比不盡相同。為了達(dá)到更1.1燃油傳輸模型加精確的空燃比控制效果,分缸空燃比控制日漸燃油傳輸動(dòng)態(tài)模型,即油膜模型,選用Xτ油興起2。另外,寬域廢氣氧傳感器(UEGO)主要膜模型(,噴出的燃油大部分直接與空氣組成混用于測(cè)量廢氣中氧氣的濃度,已經(jīng)逐漸應(yīng)用到轎合氣進(jìn)入氣缸內(nèi),其余部分(比例為X)形成油車排放控制系統(tǒng)中9。通過它得到的數(shù)據(jù),經(jīng)過膜,而油膜又進(jìn)行二次蒸發(fā)為燃油蒸氣(蒸發(fā)時(shí)間觀測(cè)算法加工后能夠精確估計(jì)氣缸內(nèi)的空燃比常數(shù)為τ),與其他燃油一同進(jìn)入氣缸。假設(shè)發(fā)動(dòng)值,從而實(shí)現(xiàn)了空燃比的精確控制。機(jī)具有n個(gè)氣缸,對(duì)于氣缸i有:本文綜合考慮燃油傳輸動(dòng)態(tài)和廢氣動(dòng)態(tài),建m(k+1)=(l-r)m(k)+ Xm(k)立了完整的油路模型。然后基于此模型設(shè)計(jì)了分ma(k+1)=m(k)+(1-X)m(k)缸空燃比的狀態(tài)/輸人觀測(cè)器。最后進(jìn)行離線和式中:i=1,2,…,n;m為壁上油膜質(zhì)量;m為噴實(shí)時(shí)仿真,試驗(yàn)結(jié)果表明所設(shè)計(jì)的觀測(cè)器可行且油器一次噴出的燃油總量,且m(k)=gta(k),g有效。為噴油器增益;m。為進(jìn)入氣缸的燃油的質(zhì)量。油路系統(tǒng)模型氣缸i內(nèi)的空燃比為,(k)=mn(k)(2)圖1為四氣缸進(jìn)氣道多點(diǎn)噴射的SI發(fā)動(dòng)機(jī)簡(jiǎn)圖。假設(shè)四沖程發(fā)動(dòng)機(jī)的每個(gè)工作循環(huán)吸入的式中:m為進(jìn)入氣缸內(nèi)的空氣質(zhì)量,m為常數(shù)空氣質(zhì)量不變,建立油路數(shù)學(xué)模型,并通過發(fā)動(dòng)機(jī)1.2廢氣混合模型仿真軟件 enDYNA以及查閱相關(guān)文獻(xiàn)0獲取?？扇蓟旌蠚饨?jīng)過壓縮、燃燒做功變?yōu)閺U氣后型參數(shù)。完整的油路模型如圖2所示,主要包括:從缸內(nèi)流向排氣歧管中。廢氣迅速膨脹,各自流燃油傳輸模型G、廢氣混合模型G灬x、混合點(diǎn)到向排氣歧管的混合點(diǎn),如圖1所示。由于氣體流氧傳感器的模型Gah。速很快,這里假設(shè)各排氣歧管等長(zhǎng),即傳輸延遲均節(jié)氣門相等。此過程可以看作是廢氣在混合點(diǎn)的合并過進(jìn)氣歧管程12。顯然,混合點(diǎn)的空燃比A是關(guān)于各個(gè)氣缸空燃比λ1的函數(shù)。四缸發(fā)動(dòng)機(jī)假設(shè)廢氣到達(dá)混合點(diǎn)之前不存在排氣管之間的廢氣混合,則一個(gè)發(fā)動(dòng)機(jī)循環(huán)內(nèi),每個(gè)排氣歧管中的空燃比為常數(shù),那么在第個(gè)排氣歧管中,到混合點(diǎn)排氣管達(dá)混合點(diǎn)的燃油可以表示為Am,m為流經(jīng)混寬扮防在氫傳成興合點(diǎn)的空氣質(zhì)量流量。因此,廢氣混合點(diǎn)處的空燃比為總的燃油質(zhì)量流量與總的空氣質(zhì)量流量之圖1四缸SI發(fā)動(dòng)機(jī)簡(jiǎn)圖比,即:Fig. 1 Four cylinders SI engineAm∑Gb(2)定義發(fā)動(dòng)機(jī)循環(huán)周期為T,s;N為發(fā)動(dòng)機(jī)轉(zhuǎn)速,r/min,所以T=120N。對(duì)于任意氣缸i,在k個(gè)循環(huán)內(nèi),只有一次排氣發(fā)生,然而在排氣管混合點(diǎn)處,一個(gè)發(fā)動(dòng)機(jī)循環(huán)之內(nèi),會(huì)連續(xù)流過n個(gè)廢氣氣流。排氣沖程階段,活塞運(yùn)行至上止點(diǎn),此Fig 2 Fuel path model時(shí)對(duì)UEGO傳感器信號(hào)進(jìn)行采樣,定義采樣周期圖2中,n為氣缸數(shù)目,t(i=1,2,…,n)為為T,T,=T。/n。由于在第k個(gè)周期的kT+噴油脈寬;λ;(i=1,2,…,n)為各缸內(nèi)的空燃(-1)T時(shí)間內(nèi),只有第j(≤i)個(gè)氣缸發(fā)生噴比;A為廢氣混合點(diǎn)的空燃比;Am為氧傳感器的油,所以對(duì)于氣缸j(>i)來說,空燃比( Air-fuel測(cè)量值。ratio,AFR)的值仍為第k-1個(gè)周期時(shí)的值,即:·1576吉林大學(xué)學(xué)報(bào)(工學(xué)版)第43卷=1(k),≤i(4)其中時(shí)間延遲δ=m+bm。并對(duì)式(11)以采樣λ,(k-1),>時(shí)間T進(jìn)行離散化,得:Gexh()=zm(1+ab1則在第k個(gè)氣缸循環(huán)內(nèi),混合點(diǎn)的n個(gè)采樣數(shù)據(jù)z amix為λ。[kT+(-1)T]=式中:amx=e(r,m);am=e-(,cm);m=8/T,;U sis LkT.+(i-1)T, Ja, (k)a=一m;b=-m一;z=er。mLkT。+(i-1)T,從混合點(diǎn)到氧傳感器輸出的離散模型可以寫∑0,使得rx Ax-dX<0(26)圖4分缸空燃比估計(jì)離線仿真方案XAT-dXFig 4 Offline individual cylinder AFR-observer structure其中:a(A)為矩陣的譜集;D(r,d)為以(d,0)為從 enDYNA軟件中導(dǎo)出UEGO傳感器的輸圓心,r為半徑的圓盤出λ∞n,作為 Input Observer模塊的輸入。將輸入在已經(jīng)求得W2的前提下,由于:觀測(cè)器的觀測(cè)結(jié)果與 enDYNA軟件中每個(gè)氣缸A一KC-B(W1C+W2CA)的AFR值A(chǔ)1,…,An進(jìn)行比較,分析估計(jì)結(jié)果的(A-Bw2CA)一KC-Bw1C=準(zhǔn)確性M一KC一Bw1C(27)為了保證系統(tǒng)極點(diǎn)更加靠近圓心,這里取式式中:M滿足:d(M一KC一BW1C)=a(M-(29的r=0.5。求得輸入觀測(cè)器(15)(16)中的CK-CW1B),所以有下面的推論。參數(shù)如下:推論1對(duì)于方陣M-CK-Cw1B1.3700K(M-CK-Cw1BT)CD(r。,0)當(dāng)且僅當(dāng)0.0217存在矩陣X>0使得W1=0.5;roX FTW2=(CB)1=11.2486;(28)FroXN=-(W1C+W2CA)=[0.15891.6787]。式中:F=MM-XKC-XBW1C將K、W1和W2帶入矩陣A一KC-B(W1C+推論2對(duì)于方陣M-CTK-Cw1TB,W2CA)中求得系統(tǒng)極點(diǎn)為:p1=-0.1558,p2a(M-cKT-crW1TB)cD(x,0),當(dāng)且僅當(dāng)=-0.495;驗(yàn)證可知A-KC-B(W1C+W2CA)存在矩陣X>0和矩陣P,Q,使得是 Hurwitz穩(wěn)定的。MTX-CT PT-CT Q在噴油脈寬為0.01s,節(jié)氣門轉(zhuǎn)角為25的條<0XM-PC-Q件下,根據(jù)圖4方案,仿真20s,試驗(yàn)結(jié)果如圖5(29)所示。式中:P=X;Q=XBW1由仿真結(jié)果可以看出:輸入觀測(cè)器估計(jì)出的當(dāng)式(29)有解PQ和x>0時(shí),就可求出分每個(gè)氣缸的AFR,與 enDYNA中每個(gè)氣缸的缸AFR輸入觀測(cè)器(15)(16)中的參數(shù)K和W即K=XP,W1=X1BQ。時(shí)間大于10s以后,估計(jì)誤差小于1%,但是在發(fā)動(dòng)機(jī)剛啟動(dòng)時(shí),估計(jì)誤差稍大,約3%~5%3仿真驗(yàn)證另外,由于第1s為 enDYNA發(fā)動(dòng)機(jī)模型的3.1離線仿真暖機(jī)過程,觀測(cè)器在第1秒內(nèi)估計(jì)結(jié)果是無效的。以 endYNa軟件中的發(fā)動(dòng)機(jī)模型為被控對(duì)總體上講輸入觀測(cè)器估計(jì)效果較好,誤差較小象,給定節(jié)氣門轉(zhuǎn)角和噴油時(shí)間來確定發(fā)動(dòng)機(jī)的3.2實(shí)時(shí)仿真工況,即保證進(jìn)入氣缸的空氣量恒定,對(duì)比實(shí)時(shí)仿真的方案如圖6所示,主要由在線仿真andina軟件中的發(fā)動(dòng)機(jī)各個(gè)氣缸的AFR與輸工具 xPC-Target(一臺(tái)主機(jī),一臺(tái)目標(biāo)機(jī))與 dSPACE入觀測(cè)器所估計(jì)的AFR,以此來評(píng)定輸入觀測(cè)器實(shí)時(shí)環(huán)境系統(tǒng)以及相應(yīng)的IO接口等組成。的估計(jì)效果,其方案如圖4所示。通過RTW工具箱、C或C十十編譯器的共第6期王萍,等:基于輸入觀測(cè)器的分缸空燃比估計(jì)1579輸入觀測(cè)器估計(jì)值enDYNA輸出enDYNA輸出0124}b789市估計(jì)值enDYNA輸出估計(jì)值 enDYNA輸出簍0110估計(jì)值 enDYNA輸出圖5節(jié)氣門轉(zhuǎn)角為25°時(shí)的離線仿真結(jié)果(a)節(jié)氣門轉(zhuǎn)角為20°Fig 5 Offline estimation results with throttle angle= 25估計(jì)值enDYNA輸出0.940.92四缸汽油17x板轉(zhuǎn)人()-)發(fā)動(dòng)機(jī)A輸出端口PC-Target目標(biāo)機(jī)口人地個(gè)叫地油路模型觀測(cè)器094 hwAN yyhtthhr界dSPACE系統(tǒng)DS04A1(k)-∠4(k)圖6分缸空燃比估計(jì)實(shí)時(shí)仿真方案Fig 6 Online individual cylinder AFR-observerSys同編譯,將 enDYNa中的發(fā)動(dòng)機(jī)模型轉(zhuǎn)化為可執(zhí)(b)節(jié)氣門轉(zhuǎn)角為35°行的C代碼,然后通過TCP/IP協(xié)議下載到運(yùn)行xPC-Target實(shí)時(shí)內(nèi)核的目標(biāo)機(jī)中,作為被控對(duì)象,斷開軟件中自帶ECU控制器的節(jié)氣門轉(zhuǎn)角A輸出輸人和燃油輸入,并給定節(jié)氣門轉(zhuǎn)角和噴油時(shí)間同時(shí)將建立的分缸空燃比輸入觀測(cè)器下載到054dsPaCe中,通過配置相應(yīng)的I/O端口,將xPCTarget與 dSPaCe系統(tǒng)連接起來。調(diào)取相應(yīng)的信號(hào),通過PCL726板卡將D/A轉(zhuǎn)換端口與dSPACE系統(tǒng)的A/D轉(zhuǎn)換端口連接,在軟件ControlDesk中對(duì)整個(gè)實(shí)時(shí)仿真試驗(yàn)進(jìn)行管理及控制。仿真中給定每個(gè)氣缸每周期的噴油時(shí)間為恒定的0.01s,將 enDYNA模型運(yùn)行至穩(wěn)態(tài),在節(jié)(c)節(jié)氣門轉(zhuǎn)角從20°變化至35°并從35°變化至25°氣門轉(zhuǎn)角分別為20°和35°,以及節(jié)氣門轉(zhuǎn)角從圖7AFR實(shí)時(shí)估計(jì)結(jié)果20°變化至35°,再?gòu)?5°變化至25°時(shí)分別進(jìn)行試Fig. 7 Real-time estimation results驗(yàn),結(jié)果如圖7所示1580吉林大學(xué)學(xué)報(bào)(工學(xué)版)第43卷從試驗(yàn)結(jié)果可以看出:輸入觀測(cè)器估計(jì)結(jié)果[6]wuJZ, Wasacz E. Estimation of individual cylinder誤差在給定節(jié)氣門轉(zhuǎn)角條件下很小,平均誤差不fuel air ratios from a switching or wide range oxygen超過0.8%。當(dāng)輸入(節(jié)氣門轉(zhuǎn)角)突變時(shí),估計(jì)sensor for engine control and on-board diagnosis]誤差增大,但經(jīng)過4s的調(diào)節(jié)時(shí)間,估計(jì)值與真實(shí)SAE International Journal of Engines, 2011. 4(1)值之間的誤差穩(wěn)定在1%以內(nèi),但是調(diào)節(jié)時(shí)間比861-873[7 Cavina N, Corti E, Moro D. Closed-loop individual較長(zhǎng)。cylinder air-fuel ratio control via UEGO signal spec-4結(jié)束語tral analysis[J]. Control Engineering Practice, 201018(11):1295-1306針對(duì)進(jìn)氣道噴射發(fā)動(dòng)機(jī),基于輸入觀測(cè)器設(shè)[8] Chen Jia-zhen, Huang yun-zhi, Zhang yuan-yuan,計(jì)了分缸空燃比估計(jì)方法,并通過區(qū)域極點(diǎn)配置et al. Development of a UEGO sensor controller方法獲得穩(wěn)定的估計(jì)器增益。通過離線和實(shí)時(shí)仿based on dsPaCe[C]//2010 IEEE International真試驗(yàn),驗(yàn)證了在進(jìn)氣不變的條件下,所建立的輸Conference on Vehicular Electronics and Safety人觀測(cè)器可以較好地對(duì)各個(gè)缸內(nèi)空燃比進(jìn)行較為Qingdao,2010:102-105.精確的估計(jì)。從而解決了在高溫高壓條件下難以[91 Shuntaro o.Nmo, Junichi K,ea.pep直接測(cè)量缸內(nèi)空燃比的問題。ment of a new model based air-fuel ratio control sys-tem[J]. SAE Int J Engines, 2009, 2(1):335-343.參考文獻(xiàn)[10]江和耀.基于輸入觀測(cè)器的分缸空燃比估計(jì)[D]長(zhǎng)春:吉林大學(xué)通信工程學(xué)院,20111] Zhai Yu-jia, Yu Ding-li. Neural network model-Jiang He- yao. Individual cylinder air-fuel ratio esti-based automotive engine air/fuel ratio control andmation based on input observer [D]. Changchun:robustness evaluation[J]. Engineering ApplicationsCollege of Communication Engineering, Jilin Uniof Artificial Intelligence, 2009, 22, 171-180.versity,[2] Kota s, Kenji S. 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