基于DSP的蓄電池充放電裝置原(yuan)理

1 引言

在蓄(xu)電(dian)(dian)(dian)池(chi)(chi)生(sheng)產過程(cheng)中，為(wei)了保證產品質量，常需(xu)對成品蓄(xu)電(dian)(dian)(dian)池(chi)(chi)進行(xing)幾次(ci)充放(fang)(fang)電(dian)(dian)(dian)處理。傳統(tong)充放(fang)(fang)電(dian)(dian)(dian)設(she)備通常采用(yong)晶閘管作為(wei)整流逆變功(gong)率(lv)器件。裝(zhuang)置(zhi)比較(jiao)復雜，交流輸進、輸出的(de)(de)功(gong)率(lv)因(yin)數較(jiao)低。對電(dian)(dian)(dian)網的(de)(de)諧波污染也比較(jiao)大。為(wei)此(ci)，設(she)計(ji)了一種三相SPWM整流逆變蓄(xu)電(dian)(dian)(dian)池(chi)(chi)充放(fang)(fang)電(dian)(dian)(dian)裝(zhuang)置(zhi)。它采用(yong)IGBT作為(wei)功(gong)率(lv)變換器件。交流側以精密(mi)鎖相的(de)(de)正弦波電(dian)(dian)(dian)流實現電(dian)(dian)(dian)能變換。可獲接近于(yu)1的(de)(de)功(gong)率(lv)因(yin)數，實現對蓄(xu)電(dian)(dian)(dian)池(chi)(chi)的(de)(de)充放(fang)(fang)電(dian)(dian)(dian)處理，明顯降低了對電(dian)(dian)(dian)網的(de)(de)諧波污染，滿(man)足了綠色環保和(he)節能的(de)(de)設(she)計(ji)要求。

2 系統結構及工作原理

圖1示(shi)出設計的(de)蓄(xu)電(dian)(dian)(dian)池生產(chan)用(yong)(yong)充放(fang)(fang)(fang)電(dian)(dian)(dian)控(kong)制系(xi)(xi)(xi)(xi)(xi)統(tong)結構(gou)。該系(xi)(xi)(xi)(xi)(xi)統(tong)從原理上可(ke)(ke)劃分為(wei)(wei)SPWM雙向逆(ni)變(bian)(bian)和DC／DC變(bian)(bian)換(huan)(huan)充放(fang)(fang)(fang)電(dian)(dian)(dian)兩個子系(xi)(xi)(xi)(xi)(xi)統(tong)。前者(zhe)(zhe)，在(zai)蓄(xu)電(dian)(dian)(dian)池充電(dian)(dian)(dian)時(shi)(shi)(shi)，通(tong)過三相(xiang)PFC升(sheng)壓(ya)(ya)控(kong)制實現AC／DC變(bian)(bian)換(huan)(huan)。將(jiang)交(jiao)流(liu)電(dian)(dian)(dian)網電(dian)(dian)(dian)壓(ya)(ya)轉(zhuan)(zhuan)換(huan)(huan)成(cheng)蓄(xu)電(dian)(dian)(dian)池充電(dian)(dian)(dian)所需(xu)的(de)直流(liu)電(dian)(dian)(dian)壓(ya)(ya)；在(zai)蓄(xu)電(dian)(dian)(dian)池放(fang)(fang)(fang)電(dian)(dian)(dian)時(shi)(shi)(shi)，通(tong)過三相(xiang)PFC恒壓(ya)(ya)逆(ni)變(bian)(bian)控(kong)制實現DC／AC變(bian)(bian)換(huan)(huan)，將(jiang)蓄(xu)電(dian)(dian)(dian)池開釋(shi)的(de)能(neng)量回(hui)饋電(dian)(dian)(dian)網。后者(zhe)(zhe)，完成(cheng)逆(ni)變(bian)(bian)直流(liu)電(dian)(dian)(dian)能(neng)與蓄(xu)電(dian)(dian)(dian)池電(dian)(dian)(dian)能(neng)的(de)轉(zhuan)(zhuan)換(huan)(huan)，以(yi)保證蓄(xu)電(dian)(dian)(dian)池充放(fang)(fang)(fang)電(dian)(dian)(dian)過程(cheng)中所要求的(de)電(dian)(dian)(dian)流(liu)、電(dian)(dian)(dian)壓(ya)(ya)和時(shi)(shi)(shi)間(jian)的(de)控(kong)制。各子系(xi)(xi)(xi)(xi)(xi)統(tong)采(cai)用(yong)(yong)單(dan)獨的(de)DSP治理，DSP部分以(yi)模板(ban)化直插(cha)結構(gou)直接(jie)插(cha)進(jin)工控(kong)機(ji)(ji)的(de)主(zhu)板(ban)，工控(kong)機(ji)(ji)承擔整個系(xi)(xi)(xi)(xi)(xi)統(tong)的(de)監控(kong)治理。系(xi)(xi)(xi)(xi)(xi)統(tong)由1個逆(ni)變(bian)(bian)子系(xi)(xi)(xi)(xi)(xi)統(tong)和n個(實驗樣(yang)機(ji)(ji)設計為(wei)(wei)15個)充放(fang)(fang)(fang)電(dian)(dian)(dian)子系(xi)(xi)(xi)(xi)(xi)統(tong)組(zu)成(cheng)。系(xi)(xi)(xi)(xi)(xi)統(tong)工作(zuo)(zuo)時(shi)(shi)(shi)，可(ke)(ke)通(tong)過工控(kong)機(ji)(ji)編組(zu)，使后路(lu)(lu)蓄(xu)電(dian)(dian)(dian)池工作(zuo)(zuo)于充電(dian)(dian)(dian)狀態；n-k路(lu)(lu)工作(zuo)(zuo)于放(fang)(fang)(fang)電(dian)(dian)(dian)狀態，這樣(yang)蓄(xu)電(dian)(dian)(dian)池能(neng)量就可(ke)(ke)直接(jie)在(zai)系(xi)(xi)(xi)(xi)(xi)統(tong)內部進(jin)行交(jiao)換(huan)(huan)，從而(er)明顯進(jin)步了節(jie)能(neng)效果。圖2示(shi)出三相(xiang)SPWM雙向逆(ni)變(bian)(bian)電(dian)(dian)(dian)路(lu)(lu)采(cai)用(yong)(yong)的(de)典型電(dian)(dian)(dian)壓(ya)(ya)型結構(gou)主(zhu)電(dian)(dian)(dian)路(lu)(lu)。

三相反饋(kui)電流(liu)iuf，ivf，iwf用于(yu)跟蹤由(you)DSP產生的(de)電流(liu)給(gei)定(ding)(ding)信號，從而控制直流(liu)端電壓Ud的(de)穩定(ding)(ding)；Ud的(de)反饋(kui)電壓Ut的(de)值經DSP采樣后通過電壓調節得到(dao)作用于(yu)電流(liu)內(nei)環的(de)電流(liu)給(gei)定(ding)(ding)值。

圖(tu)3示(shi)出單相(xiang)(xiang)(xiang)(xiang)(xiang)PWM整(zheng)流電(dian)路(lu)的(de)(de)相(xiang)(xiang)(xiang)(xiang)(xiang)量圖(tu)[2]。固然該(gai)系統采用的(de)(de)是三(san)(san)相(xiang)(xiang)(xiang)(xiang)(xiang)PWM整(zheng)流電(dian)路(lu)．但其工作原(yuan)理與單相(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)路(lu)相(xiang)(xiang)(xiang)(xiang)(xiang)似，只是從單相(xiang)(xiang)(xiang)(xiang)(xiang)擴展到三(san)(san)相(xiang)(xiang)(xiang)(xiang)(xiang)。對電(dian)路(lu)進行SPWM控制，在橋(qiao)的(de)(de)交流輸進端A，B，C可得到三(san)(san)相(xiang)(xiang)(xiang)(xiang)(xiang)橋(qiao)臂的(de)(de)SPWM電(dian)壓uiu，uiv，uiw。對其各(ge)相(xiang)(xiang)(xiang)(xiang)(xiang)按圖(tu)3的(de)(de)相(xiang)(xiang)(xiang)(xiang)(xiang)量圖(tu)進行控制，就可使各(ge)相(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)流iu，iv，iw為(wei)(wei)正弦(xian)波。且與電(dian)壓同(tong)相(xiang)(xiang)(xiang)(xiang)(xiang)位，功(gong)率因數(shu)近似為(wei)(wei)1。

由此可知，控(kong)(kong)制uiu的(de)大小(xiao)和相位δ即可控(kong)(kong)制電流的(de)大小(xiao)和流向，從而控(kong)(kong)制功率的(de)大小(xiao)和方向。通過對(dui)Ud的(de)恒壓控(kong)(kong)制，實現逆變器的(de)功率流向，從而實現能量的(de)自(zi)動雙向活動。

3 電壓控制器的設計

圖4示出AD／DC逆變控(kong)制(zhi)框圖。該系統采(cai)用電(dian)(dian)壓、電(dian)(dian)流(liu)(liu)雙閉環控(kong)制(zhi)結構，其電(dian)(dian)壓控(kong)制(zhi)對(dui)象(xiang)為直流(liu)(liu)量(liang)；電(dian)(dian)流(liu)(liu)控(kong)制(zhi)對(dui)象(xiang)為交(jiao)流(liu)(liu)量(liang)。電(dian)(dian)壓外環采(cai)用數字算(suan)法予以實現(xian)；電(dian)(dian)流(liu)(liu)內環采(cai)用模擬(ni)電(dian)(dian)路(lu)予以實現(xian)，以確(que)保(bao)快(kuai)速進(jin)行電(dian)(dian)流(liu)(liu)控(kong)制(zhi)，進(jin)步系統工作的可靠性。同時，為了使誤差電(dian)(dian)流(liu)(liu)與給(gei)定(ding)相位保(bao)持一致。電(dian)(dian)流(liu)(liu)調節器(qi)采(cai)用比例控(kong)制(zhi)。

蓄(xu)電(dian)(dian)(dian)池(chi)(chi)充電(dian)(dian)(dian)時(shi)，輸(shu)(shu)出電(dian)(dian)(dian)壓(ya)Ud低于給(gei)定(ding)(ding)(ding)(ding)值Ud*，則電(dian)(dian)(dian)壓(ya)調節器(qi)輸(shu)(shu)出正的(de)uc，輸(shu)(shu)進電(dian)(dian)(dian)壓(ya)Uin經過一個比例因(yin)(yin)子(zi)Ku后得(de)到一個與Uin同相的(de)單位(wei)正弦(xian)us，uc與us的(de)乘積作為(wei)給(gei)定(ding)(ding)(ding)(ding)電(dian)(dian)(dian)流(liu)(liu)(liu)i*，與Uin同相，控制i跟(gen)隨i*，則能(neng)(neng)量就以單位(wei)功(gong)率(lv)(lv)因(yin)(yin)數從(cong)電(dian)(dian)(dian)網(wang)流(liu)(liu)(liu)向蓄(xu)電(dian)(dian)(dian)池(chi)(chi)。此(ci)時(shi)，變(bian)流(liu)(liu)(liu)器(qi)工作在(zai)整流(liu)(liu)(liu)狀態。蓄(xu)電(dian)(dian)(dian)池(chi)(chi)放電(dian)(dian)(dian)時(shi)，Ud高于Ud*，則uc為(wei)負值，uc與us相乘得(de)到與Uin反向的(de)給(gei)定(ding)(ding)(ding)(ding)電(dian)(dian)(dian)流(liu)(liu)(liu)i*，控制i跟(gen)隨i*，能(neng)(neng)量就能(neng)(neng)以單位(wei)功(gong)率(lv)(lv)因(yin)(yin)數從(cong)蓄(xu)電(dian)(dian)(dian)池(chi)(chi)流(liu)(liu)(liu)向電(dian)(dian)(dian)網(wang)。此(ci)時(shi)，變(bian)流(liu)(liu)(liu)器(qi)工作在(zai)逆變(bian)狀態。電(dian)(dian)(dian)壓(ya)外環產生(sheng)輸(shu)(shu)進給(gei)定(ding)(ding)(ding)(ding)電(dian)(dian)(dian)流(liu)(liu)(liu)i*，其幅(fu)值表明了功(gong)率(lv)(lv)的(de)大小；符號決(jue)定(ding)(ding)(ding)(ding)了功(gong)率(lv)(lv)的(de)流(liu)(liu)(liu)向；相位(wei)決(jue)定(ding)(ding)(ding)(ding)了能(neng)(neng)量傳遞的(de)功(gong)率(lv)(lv)因(yin)(yin)數。電(dian)(dian)(dian)流(liu)(liu)(liu)內環使(shi)輸(shu)(shu)進電(dian)(dian)(dian)流(liu)(liu)(liu)跟(gen)蹤給(gei)定(ding)(ding)(ding)(ding)，從(cong)而實現可逆的(de)單位(wei)功(gong)率(lv)(lv)因(yin)(yin)數變(bian)換。

系(xi)統采用TMS320LF2407A DSP作(zuo)為(wei)主處理(li)器，因其有豐富的外設和較高的運算速度。由(you)此可實現較復雜的控(kong)制(zhi)及高精度的數據處理(li)。在此，通過對PI控(kong)制(zhi)、IP控(kong)制(zhi)和變(bian)速積分PI控(kong)制(zhi)三種電(dian)壓調節器算法的實驗得出其優劣，從而選擇(ze)最適合(he)該系(xi)統的控(kong)制(zhi)算法進行電(dian)壓調節。

(1)PI控制算法和IP控制算法

圖5a示出PI調節器結構圖。由圖可(ke)得其(qi)傳遞(di)

比較式(shi)(5)和式(shi)(6)可見，兩(liang)種系(xi)統的(de)(de)傳遞函(han)數分(fen)母(mu)相(xiang)(xiang)同(tong)，故(gu)IP調(diao)節(jie)器可持有(you)(you)與PI相(xiang)(xiang)同(tong)的(de)(de)無靜差調(diao)節(jie)和穩定(ding)特性(xing)，同(tong)時因它在傳遞函(han)數上(shang)比PI少一個(ge)零點，因此具有(you)(you)比PI更好的(de)(de)高(gao)頻(pin)衰減特性(xing)，輕(qing)易滿足較長(chang)采(cai)樣(yang)周期數字調(diao)節(jie)的(de)(de)穩定(ding)性(xing)要求，能有(you)(you)效抑(yi)制(zhi)混迭(die)現(xian)象。系(xi)統實(shi)驗證實(shi)，采(cai)用IP調(diao)節(jie)，調(diao)節(jie)器參數很輕(qing)易整定(ding)。可使系(xi)統達到穩定(ding)、無靜差和很小的(de)(de)超調(diao)。不過在快速性(xing)方面將有(you)(you)損失。

(2)變速積分PI控制算法

在傳統(tong)的(de)PI算法(fa)中(zhong)，因積(ji)(ji)(ji)(ji)(ji)分(fen)(fen)增(zeng)益Ki為常數(shu)，在整個調節過程中(zhong)，其值不變(bian)。但系統(tong)對積(ji)(ji)(ji)(ji)(ji)分(fen)(fen)的(de)要求是偏(pian)(pian)差大時，積(ji)(ji)(ji)(ji)(ji)分(fen)(fen)作(zuo)用(yong)減弱，否則會(hui)產生超(chao)調，甚至出(chu)現積(ji)(ji)(ji)(ji)(ji)分(fen)(fen)飽和；反之(zhi)則加強(qiang)，否則不能(neng)滿足(zu)正確性(xing)的(de)要求。引進變(bian)速(su)積(ji)(ji)(ji)(ji)(ji)分(fen)(fen)PI控制算法(fa)能(neng)使(shi)控制性(xing)能(neng)得以滿足(zu)。其基本思路(lu)是偏(pian)(pian)差大時，積(ji)(ji)(ji)(ji)(ji)分(fen)(fen)累(lei)積(ji)(ji)(ji)(ji)(ji)速(su)度(du)慢，積(ji)(ji)(ji)(ji)(ji)分(fen)(fen)作(zuo)用(yong)弱；偏(pian)(pian)差小時，積(ji)(ji)(ji)(ji)(ji)分(fen)(fen)累(lei)積(ji)(ji)(ji)(ji)(ji)速(su)度(du)快，積(ji)(ji)(ji)(ji)(ji)分(fen)(fen)作(zuo)用(yong)強(qiang)。為此(ci)，設(she)置系數(shu)f[E(k)]，它(ta)是偏(pian)(pian)差E(k)的(de)函數(shu)，當(dang)E(k)增(zeng)大時，f[E(k)]減小；反之(zhi)則增(zeng)大。每次(ci)采樣后(hou)，用(yong)f[E(k)]乘E(k)，再進行累(lei)加。f[E(k)]與E(k)的(de)關系可表示(shi)為：

在該(gai)系統(tong)中，采用簡(jian)單的(de)變速積(ji)(ji)分PI控制，取A=32，B=8，當誤差(cha)大于(yu)(yu)40時，系統(tong)相當于(yu)(yu)采用純比(bi)例調(diao)節，因此響應(ying)速度加快；當誤差(cha)小(xiao)(xiao)于(yu)(yu)40并減小(xiao)(xiao)到8的(de)過(guo)程(cheng)中，積(ji)(ji)分作(zuo)用開始并逐漸增強，響應(ying)過(guo)程(cheng)快速平滑；當誤差(cha)小(xiao)(xiao)于(yu)(yu)8時，完全引進積(ji)(ji)分作(zuo)用，能快速有效地(di)消除靜差(cha)。該(gai)方法可有效抑制系統(tong)的(de)超(chao)調(diao)，同(tong)時也可兼顧系統(tong)的(de)響應(ying)速度。

4 實驗結果

利用(yong)PI，IP和(he)變(bian)速(su)積(ji)(ji)(ji)分PI數字(zi)電(dian)壓(ya)(ya)調(diao)(diao)(diao)節(jie)器(qi)(qi)的(de)(de)逆(ni)變(bian)子系(xi)統對該設計方(fang)案進行了大(da)量實(shi)驗。結果可見(jian)，采用(yong)變(bian)速(su)積(ji)(ji)(ji)分PI數字(zi)電(dian)壓(ya)(ya)調(diao)(diao)(diao)節(jie)器(qi)(qi)的(de)(de)綜合性(xing)能優于(yu)(yu)前兩種算(suan)法。圖(tu)6示出(chu)采用(yong)PI調(diao)(diao)(diao)節(jie)、IP調(diao)(diao)(diao)節(jie)，以及變(bian)速(su)積(ji)(ji)(ji)分PI調(diao)(diao)(diao)節(jie)時用(yong)100M-Tektronix TDS220存儲示波器(qi)(qi)獲取的(de)(de)一組直流(liu)母線(xian)電(dian)壓(ya)(ya)Ud的(de)(de)實(shi)驗對比波形。逆(ni)變(bian)器(qi)(qi)起(qi)動(dong)時Ud由150V升(sheng)至200V。由圖(tu)6可見(jian)。3種調(diao)(diao)(diao)節(jie)器(qi)(qi)在(zai)無靜差調(diao)(diao)(diao)節(jie)方(fang)面的(de)(de)性(xing)能相同(tong)，而IP的(de)(de)上升(sheng)時間明(ming)顯(xian)大(da)于(yu)(yu)另外兩種算(suan)法；在(zai)抑(yi)制超調(diao)(diao)(diao)及高頻(pin)噪聲誘發振蕩方(fang)面，變(bian)速(su)積(ji)(ji)(ji)分PI法有著明(ming)顯(xian)的(de)(de)上風，PI系(xi)統的(de)(de)起(qi)動(dong)超調(diao)(diao)(diao)超過20V，IP系(xi)統的(de)(de)超調(diao)(diao)(diao)不到(dao)10V，而變(bian)速(su)積(ji)(ji)(ji)分PI系(xi)統則(ze)無超調(diao)(diao)(diao)。無振蕩，能很(hen)快(kuai)進進穩定狀態：在(zai)抗干擾(rao)性(xing)能方(fang)面，變(bian)速(su)積(ji)(ji)(ji)分PI系(xi)統也具有同(tong)樣(yang)的(de)(de)特點。

5 結論

先容的(de)逆變器(qi)采用了直流(liu)(liu)母線電(dian)壓的(de)恒(heng)壓數字(zi)調(diao)(diao)節(jie)，可方便地實現電(dian)網(wang)能(neng)(neng)(neng)量和蓄(xu)電(dian)池(chi)能(neng)(neng)(neng)量的(de)雙向活(huo)動，精密鎖相的(de)SPWM控(kong)制(zhi)可獲(huo)(huo)得(de)接近于(yu)1的(de)功率因數，理論分(fen)析和系(xi)統(tong)實驗表明(ming)，在DSP控(kong)制(zhi)采樣(yang)周期(qi)即是交流(liu)(liu)電(dian)源周期(qi)的(de)交流(liu)(liu)控(kong)制(zhi)系(xi)統(tong)中，采用變速積分(fen)PI調(diao)(diao)節(jie)更易獲(huo)(huo)得(de)小(xiao)超(chao)調(diao)(diao)、無(wu)振蕩、無(wu)靜差的(de)控(kong)制(zhi)性(xing)能(neng)(neng)(neng)指(zhi)標。該設計系(xi)統(tong)可攜帶15路(lu)3A蓄(xu)電(dian)池(chi)組(每組12V蓄(xu)電(dian)池(chi)15節(jie)串聯)進(jin)行充放電(dian)子系(xi)統(tong)工(gong)作，每路(lu)工(gong)作由工(gong)控(kong)機編程獨立控(kong)制(zhi)。通過對充電(dian)組和放電(dian)組的(de)公道配置(zhi)，可獲(huo)(huo)得(de)明(ming)顯的(de)節(jie)能(neng)(neng)(neng)效果。