一、前言

　　開關電源系(xi)(xi)(xi)統是(shi)弱電(dian)(dian)(dian)控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)強電(dian)(dian)(dian)的(de)系(xi)(xi)(xi)統。開關電(dian)(dian)(dian)源系(xi)(xi)(xi)統主(zhu)(zhu)要可以分(fen)(fen)為主(zhu)(zhu)功(gong)率(lv)(lv)(lv)(lv)(lv)電(dian)(dian)(dian)路(lu)和控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)電(dian)(dian)(dian)路(lu)兩(liang)部分(fen)(fen)。主(zhu)(zhu)功(gong)率(lv)(lv)(lv)(lv)(lv)電(dian)(dian)(dian)路(lu)是(shi)由變(bian)(bian)換器(qi)構成(cheng)。變(bian)(bian)換器(qi)是(shi)應用功(gong)率(lv)(lv)(lv)(lv)(lv)半導體器(qi)件，對(dui)電(dian)(dian)(dian)能(neng)(neng)進行變(bian)(bian)換的(de)裝(zhuang)置，變(bian)(bian)換量包括電(dian)(dian)(dian)壓、電(dian)(dian)(dian)流、頻(pin)率(lv)(lv)(lv)(lv)(lv)和波(bo)形等方(fang)面，以達到電(dian)(dian)(dian)能(neng)(neng)更好符合各種(zhong)不同用電(dian)(dian)(dian)設備要求的(de)目的(de)。這(zhe)是(shi)通過(guo)對(dui)功(gong)率(lv)(lv)(lv)(lv)(lv)半導體器(qi)件的(de)開關的(de)控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)來(lai)實現的(de)。因此主(zhu)(zhu)功(gong)率(lv)(lv)(lv)(lv)(lv)電(dian)(dian)(dian)路(lu)是(shi)開關電(dian)(dian)(dian)源控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)系(xi)(xi)(xi)統中(zhong)的(de)被控(kong)(kong)(kong)對(dui)象，而控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)功(gong)率(lv)(lv)(lv)(lv)(lv)半導體器(qi)件的(de)開關以實現既定(ding)的(de)性(xing)能(neng)(neng)是(shi)控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)裝(zhuang)置的(de)主(zhu)(zhu)要工作。將被控(kong)(kong)(kong)對(dui)象和控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)裝(zhuang)置按照(zhao)一(yi)定(ding)的(de)方(fang)式連接起來(lai)，組成(cheng)一(yi)個有(you)機的(de)總體，就構成(cheng)開關電(dian)(dian)(dian)源的(de)控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)系(xi)(xi)(xi)統，這(zhe)樣的(de)電(dian)(dian)(dian)路(lu)即為控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)電(dian)(dian)(dian)路(lu)。控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)系(xi)(xi)(xi)統的(de)工作方(fang)式有(you)多種(zhong)，其中(zhong)最基本的(de)一(yi)種(zhong)是(shi)基于反饋(kui)控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)原理的(de)閉環控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)系(xi)(xi)(xi)統。而大部分(fen)(fen)的(de)開關電(dian)(dian)(dian)源控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)系(xi)(xi)(xi)統是(shi)閉環控(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)系(xi)(xi)(xi)統。

　　二、閉環控制原理

　　通常，我(wo)們把被(bei)控量(liang)(liang)送(song)回到控制系(xi)統(tong)的(de)(de)(de)(de)輸入(ru)(ru)端(duan)，與(yu)參據量(liang)(liang)相(xiang)比較產生(sheng)(sheng)誤差信號的(de)(de)(de)(de)過(guo)程(cheng)，稱為反(fan)(fan)(fan)饋。若反(fan)(fan)(fan)饋的(de)(de)(de)(de)信號是(shi)與(yu)參據量(liang)(liang)相(xiang)減，使得(de)產生(sheng)(sheng)的(de)(de)(de)(de)偏差越來越小，稱為負反(fan)(fan)(fan)饋。由于引(yin)入(ru)(ru)了被(bei)控量(liang)(liang)的(de)(de)(de)(de)反(fan)(fan)(fan)饋信息，整個控制過(guo)程(cheng)成為閉合的(de)(de)(de)(de)，因此也稱閉環控制，如圖(tu)1所示。

圖1  反饋控(kong)制框圖

　　三、基本組成

　　控制裝(zhuang)置(zhi)是由具(ju)有一定職能的(de)各種基本元器件組成。系統的(de)元器件按照職能分類主(zhu)要有以(yi)下幾種：

　　測量(liang)單元：其職能是檢測被(bei)控制(zhi)的物理量(liang)。這(zhe)個(ge)被(bei)控量(liang)一般(ban)為主功率電路的輸出電壓、主功率電路的輸入(ru)電流(liu)等。

　　給定單元：其職(zhi)能是給出與期望的被控量(liang)相對應的參據量(liang)，即(ji)給定量(liang)。在開關(guan)電源系統(tong)中(zhong)，給定量(liang)一般為直流常量(liang)或者是交流正弦(xian)量(liang)。

　　比(bi)(bi)較(jiao)(jiao)單(dan)元：其職能是將檢測到的(de)(de)被控制量的(de)(de)實際值與參據(ju)量進行比(bi)(bi)較(jiao)(jiao)，求(qiu)出他們之(zhi)間的(de)(de)偏差。

　　校正單元：即補(bu)償(chang)單元，用串聯(lian)方式(shi)(shi)或者(zhe)反饋方式(shi)(shi)（并聯(lian)方式(shi)(shi)）等方式(shi)(shi)連接(jie)在系統(tong)中(zhong)，以(yi)(yi)改善系統(tong)的性(xing)能。這個補(bu)償(chang)網絡是(shi)控(kong)制系統(tong)的核心部(bu)分(fen)(fen)，是(shi)決(jue)定控(kong)制系統(tong)性(xing)能的關鍵部(bu)分(fen)(fen)。可(ke)以(yi)(yi)通過(guo)由電阻、電容組成的無源或有源網絡實現，也可(ke)以(yi)(yi)通過(guo)MCU、DSP這些數字(zi)器件輔(fu)助實現。

　　四、外作用類型

　　一(yi)般(ban)加在開關電(dian)(dian)源(yuan)系(xi)(xi)統(tong)上(shang)的(de)(de)外作用有兩(liang)種類型：一(yi)種是(shi)有用輸(shu)入，它(ta)決定(ding)(ding)系(xi)(xi)統(tong)被控量的(de)(de)變化規律，比如(ru)給定(ding)(ding)量；一(yi)種是(shi)系(xi)(xi)統(tong)不(bu)希望有的(de)(de)外作用，即擾(rao)(rao)動(dong)，它(ta)破壞有用輸(shu)入對系(xi)(xi)統(tong)的(de)(de)控制。在實際系(xi)(xi)統(tong)中，擾(rao)(rao)動(dong)是(shi)不(bu)可避免(mian)的(de)(de)。這(zhe)樣的(de)(de)擾(rao)(rao)動(dong)包(bao)括(kuo)：主功率電(dian)(dian)路輸(shu)入電(dian)(dian)壓的(de)(de)波(bo)動(dong)，主功率電(dian)(dian)路輸(shu)出電(dian)(dian)流的(de)(de)波(bo)動(dong)或者負(fu)載的(de)(de)波(bo)動(dong)，元(yuan)器件參(can)數的(de)(de)溫度漂移等。

      五、基本控制方式

　　反饋控制(zhi)是(shi)系統最基(ji)本的控制(zhi)方式，也是(shi)應用最廣泛的一種(zhong)控制(zhi)方式。此(ci)外(wai)，還有開環控制(zhi)方式和(he)復合(he)控制(zhi)方式，它們都有著各自的特點和(he)不同的應用場合(he)。

　　（1）反饋控制方式

　　如前面所提及，反饋控(kong)(kong)制(zhi)方式(shi)是按(an)照偏(pian)差進行(xing)控(kong)(kong)制(zhi)的，其特點是不論什么(me)原因使被(bei)控(kong)(kong)量偏(pian)離期望(wang)值(zhi)而出現偏(pian)差時(shi)，必定會產生一(yi)個相應的控(kong)(kong)制(zhi)作用(yong)去(qu)減小或消(xiao)除這個偏(pian)差，使被(bei)控(kong)(kong)量與(yu)期望(wang)值(zhi)趨(qu)于一(yi)致。可見，按(an)照反饋控(kong)(kong)制(zhi)方式(shi)設(she)計的控(kong)(kong)制(zhi)系統，具有(you)抑制(zhi)任何(he)內、外擾動對被(bei)控(kong)(kong)量產生影(ying)響的能力，有(you)較高的穩態精度。

　　如圖(tu)2所示為電壓(ya)型控制(zhi)(zhi)Boost變換器控制(zhi)(zhi)框圖(tu)，電壓(ya)反(fan)饋控制(zhi)(zhi)技術是開關電源系統中經典的反(fan)饋控制(zhi)(zhi)方法(fa)。這是60年(nian)代后期開關穩(wen)壓(ya)電源剛(gang)剛(gang)開始發展就采用的第一(yi)種(zhong)控制(zhi)(zhi)方法(fa)，該方法(fa)與一(yi)些(xie)必要的過電流(liu)保護電路相(xiang)結合，至(zhi)今仍然被廣泛的應用。

圖2  電壓型(xing)控制(zhi) Boost 變換(huan)器控制(zhi)框圖

　　（2）開環控(kong)制方(fang)式

　　開環(huan)(huan)控(kong)(kong)(kong)制(zhi)(zhi)方(fang)式是指被控(kong)(kong)(kong)裝置(zhi)與被控(kong)(kong)(kong)對(dui)象(xiang)之間(jian)只(zhi)有順(shun)向作用而沒有反向聯系(xi)的(de)(de)控(kong)(kong)(kong)制(zhi)(zhi)過程。按(an)這種控(kong)(kong)(kong)制(zhi)(zhi)方(fang)式組(zu)成的(de)(de)控(kong)(kong)(kong)制(zhi)(zhi)系(xi)統(tong)稱(cheng)為開環(huan)(huan)控(kong)(kong)(kong)制(zhi)(zhi)系(xi)統(tong)，其特點是系(xi)統(tong)的(de)(de)輸出量(liang)不(bu)會對(dui)系(xi)統(tong)的(de)(de)控(kong)(kong)(kong)制(zhi)(zhi)作用發生(sheng)影響(xiang)。這種控(kong)(kong)(kong)制(zhi)(zhi)方(fang)式也(ye)稱(cheng)為前饋(kui)控(kong)(kong)(kong)制(zhi)(zhi)、順(shun)饋(kui)控(kong)(kong)(kong)制(zhi)(zhi)。開環(huan)(huan)控(kong)(kong)(kong)制(zhi)(zhi)系(xi)統(tong)可(ke)以(yi)(yi)由按(an)給定量(liang)控(kong)(kong)(kong)制(zhi)(zhi)的(de)(de)控(kong)(kong)(kong)制(zhi)(zhi)方(fang)式組(zu)成，也(ye)可(ke)以(yi)(yi)由按(an)擾動控(kong)(kong)(kong)制(zhi)(zhi)的(de)(de)控(kong)(kong)(kong)制(zhi)(zhi)方(fang)式組(zu)成。

　　按給(gei)定量(liang)控(kong)(kong)制(zhi)的(de)(de)開環控(kong)(kong)制(zhi)系統，其控(kong)(kong)制(zhi)作用(yong)(yong)直接由控(kong)(kong)制(zhi)系統的(de)(de)輸(shu)入量(liang)產生，給(gei)定一(yi)個輸(shu)入量(liang)，就有(you)(you)一(yi)個輸(shu)出(chu)量(liang)與之相對應，控(kong)(kong)制(zhi)精度(du)完全取決于控(kong)(kong)制(zhi)電路所用(yong)(yong)的(de)(de)元器(qi)件以及主(zhu)功率電路的(de)(de)特性，如圖3所示。這種控(kong)(kong)制(zhi)方(fang)式(shi)(shi)沒有(you)(you)自(zi)動(dong)修正偏差(cha)的(de)(de)能(neng)力，抗(kang)擾動(dong)能(neng)力差(cha)。但由于其結構簡單、調整方(fang)便(bian)、成(cheng)本低，在精度(du)要求不(bu)高或(huo)擾動(dong)影響較(jiao)小的(de)(de)情況下，這種控(kong)(kong)制(zhi)方(fang)式(shi)(shi)還是有(you)(you)一(yi)定的(de)(de)實用(yong)(yong)價值。

圖3  按(an)給定(ding)量控(kong)制的開環控(kong)制系統

如(ru)圖4所示的(de)采(cai)用(yong)(yong)電(dian)容(rong)的(de)開關(guan)功(gong)率變(bian)換器，一般(ban)為多(duo)級變(bian)換電(dian)路中(zhong)的(de)其中(zhong)一級，通常采(cai)用(yong)(yong)開環控制，效率和功(gong)率密度較(jiao)高，容(rong)易實現開關(guan)，具有廣(guang)泛的(de)應用(yong)(yong)前景(jing)。

圖(tu)4  開環(huan)控制的(de)開關電容功率變(bian)換器

　　按擾動(dong)(dong)(dong)(dong)(dong)控制的開環控制系統，是利用(yong)可測量(liang)(liang)(liang)的擾動(dong)(dong)(dong)(dong)(dong)量(liang)(liang)(liang)，產生一(yi)種補(bu)償作(zuo)用(yong)，以減少(shao)或(huo)抵消(xiao)擾動(dong)(dong)(dong)(dong)(dong)對輸出量(liang)(liang)(liang)的影響，如圖5所示。這種控制方(fang)式直(zhi)接從(cong)擾動(dong)(dong)(dong)(dong)(dong)取得信息，并(bing)據此改變被控量(liang)(liang)(liang)，因(yin)此其抗(kang)擾動(dong)(dong)(dong)(dong)(dong)性好，控制精度也較高，但(dan)它(ta)只(zhi)適用(yong)于擾動(dong)(dong)(dong)(dong)(dong)是可以測量(liang)(liang)(liang)的場合，而且一(yi)個補(bu)償裝置只(zhi)能補(bu)償一(yi)個擾動(dong)(dong)(dong)(dong)(dong)因(yin)素，對其余擾動(dong)(dong)(dong)(dong)(dong)均(jun)不起補(bu)償作(zuo)用(yong)。

圖5  按擾動(dong)控制的開環控制系統

　　如圖(tu)6所示為單(dan)周期控制Buck變(bian)(bian)換器控制框圖(tu)，單(dan)周期控制技術(shu)實際上(shang)就是一種按擾(rao)動(dong)控制的(de)(de)(de)開(kai)環控制系統。它將主(zhu)功率(lv)電(dian)(dian)路(lu)的(de)(de)(de)輸入(ru)電(dian)(dian)壓引入(ru)控制，隨著(zhu)輸入(ru)電(dian)(dian)壓的(de)(de)(de)變(bian)(bian)化，得(de)到不同的(de)(de)(de)占空度(du)，使得(de)主(zhu)功率(lv)電(dian)(dian)路(lu)的(de)(de)(de)輸出電(dian)(dian)壓跟隨給(gei)定量。理論上(shang)這種控制技術(shu)完全抵制了主(zhu)功率(lv)電(dian)(dian)路(lu)的(de)(de)(de)輸出電(dian)(dian)壓擾(rao)動(dong)，但(dan)是對負載的(de)(de)(de)擾(rao)動(dong)卻無能(neng)為力(li)。

圖6  單周期控(kong)制 Buck 變換(huan)器(qi)控(kong)制框(kuang)圖

 （3）復合控制方式

　　開環控制方式在技術上較反饋控制方式簡單，且對激勵響應快，但是僅僅只采用按給定量控制的前饋控制方式來控制，系統控制精度不高。而按擾動控制的開環控制系統只適用于擾動可以測量的場合。因此，比較合理的一種控制方式是把開環控制方式與反饋控制方式結合起來。這種控制方式稱為復合控制。利用控制系統的給定量，產生一種補償作用，使得被控量更好的跟隨給定量。另外，對主要擾動采用適當的補償裝置來實現擾動控制。同時，再組成反饋控制系統實現按偏差控制，以消除其余擾動產生的偏差。這樣，系統的主要外作用已被補償，反饋控制系統比較容易設計，控制效果也會更好。這種將前饋控制和反饋控制相結合的控制方式稱為復合控制。
如圖7所示為(wei)(wei)具有(you)輸(shu)(shu)(shu)(shu)入(ru)(ru)(ru)電壓(ya)(ya)(ya)前饋(kui)的(de)平(ping)均(jun)電流(liu)控(kong)(kong)(kong)(kong)制(zhi)Boost變換(huan)器(qi)的(de)PFC控(kong)(kong)(kong)(kong)制(zhi)框圖，這種控(kong)(kong)(kong)(kong)制(zhi)方(fang)法(fa)為(wei)(wei)雙環(huan)(huan)反饋(kui)的(de)控(kong)(kong)(kong)(kong)制(zhi)方(fang)法(fa)，外環(huan)(huan)為(wei)(wei)母線電壓(ya)(ya)(ya)平(ping)均(jun)值(zhi)控(kong)(kong)(kong)(kong)制(zhi)環(huan)(huan)，內(nei)環(huan)(huan)為(wei)(wei)輸(shu)(shu)(shu)(shu)入(ru)(ru)(ru)電流(liu)控(kong)(kong)(kong)(kong)制(zhi)環(huan)(huan)。該(gai)控(kong)(kong)(kong)(kong)制(zhi)方(fang)法(fa)將輸(shu)(shu)(shu)(shu)出(chu)電壓(ya)(ya)(ya)的(de)平(ping)均(jun)值(zhi)作為(wei)(wei)反饋(kui)與(yu)基(ji)準比(bi)(bi)較(jiao)，產(chan)生的(de)誤差信(xin)(xin)(xin)號(hao)(hao)經由(you)電壓(ya)(ya)(ya)補償器(qi)進(jin)行(xing)調節。產(chan)生的(de)信(xin)(xin)(xin)號(hao)(hao)與(yu)輸(shu)(shu)(shu)(shu)入(ru)(ru)(ru)電壓(ya)(ya)(ya)有(you)效值(zhi)一起(qi)，控(kong)(kong)(kong)(kong)制(zhi)正(zheng)弦(xian)波基(ji)準的(de)幅值(zhi)。再將輸(shu)(shu)(shu)(shu)入(ru)(ru)(ru)電流(liu)作為(wei)(wei)反饋(kui)與(yu)正(zheng)弦(xian)波基(ji)準進(jin)行(xing)比(bi)(bi)較(jiao)，產(chan)生的(de)誤差信(xin)(xin)(xin)號(hao)(hao)經由(you)電流(liu)補償器(qi)進(jin)行(xing)調節產(chan)生調制(zhi)信(xin)(xin)(xin)號(hao)(hao)，再將該(gai)調制(zhi)信(xin)(xin)(xin)號(hao)(hao)與(yu)載(zai)波比(bi)(bi)較(jiao)得到控(kong)(kong)(kong)(kong)制(zhi)信(xin)(xin)(xin)號(hao)(hao)，得到所需(xu)的(de)控(kong)(kong)(kong)(kong)制(zhi)信(xin)(xin)(xin)號(hao)(hao)，外環(huan)(huan)的(de)作用，主(zhu)要控(kong)(kong)(kong)(kong)制(zhi)輸(shu)(shu)(shu)(shu)出(chu)電壓(ya)(ya)(ya)，內(nei)環(huan)(huan)主(zhu)要控(kong)(kong)(kong)(kong)制(zhi)輸(shu)(shu)(shu)(shu)入(ru)(ru)(ru)電流(liu)的(de)波形(xing)，保證輸(shu)(shu)(shu)(shu)入(ru)(ru)(ru)電流(liu)的(de)正(zheng)弦(xian)度。引入(ru)(ru)(ru)了輸(shu)(shu)(shu)(shu)入(ru)(ru)(ru)電壓(ya)(ya)(ya)前饋(kui)，克服輸(shu)(shu)(shu)(shu)入(ru)(ru)(ru)電壓(ya)(ya)(ya)擾動(dong)對輸(shu)(shu)(shu)(shu)出(chu)電壓(ya)(ya)(ya)的(de)影響。

圖7  具有輸入電壓前(qian)饋的平(ping)均電流(liu)控制(zhi) Boost 變換器的PFC

　　六、校正方式

　　對(dui)控(kong)制系(xi)(xi)(xi)(xi)統(tong)(tong)的(de)(de)要(yao)求(qiu)，通(tong)常以(yi)性(xing)能指標的(de)(de)形(xing)式(shi)給(gei)出。而(er)為(wei)了使系(xi)(xi)(xi)(xi)統(tong)(tong)獲得滿意的(de)(de)性(xing)能，必須對(dui)控(kong)制系(xi)(xi)(xi)(xi)統(tong)(tong)進行設計和校(xiao)(xiao)(xiao)正(zheng)，也(ye)就是在(zai)(zai)系(xi)(xi)(xi)(xi)統(tong)(tong)中適當的(de)(de)位置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)加進適當的(de)(de)校(xiao)(xiao)(xiao)正(zheng)裝(zhuang)置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)。校(xiao)(xiao)(xiao)正(zheng)裝(zhuang)置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)彌補了原系(xi)(xi)(xi)(xi)統(tong)(tong)的(de)(de)性(xing)能缺陷。按照校(xiao)(xiao)(xiao)正(zheng)裝(zhuang)置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)在(zai)(zai)開關(guan)電源系(xi)(xi)(xi)(xi)統(tong)(tong)中的(de)(de)連接(jie)方式(shi)，控(kong)制系(xi)(xi)(xi)(xi)統(tong)(tong)的(de)(de)校(xiao)(xiao)(xiao)正(zheng)方式(shi)可以(yi)分(fen)為(wei)串(chuan)(chuan)聯(lian)校(xiao)(xiao)(xiao)正(zheng)、反饋(kui)(kui)校(xiao)(xiao)(xiao)正(zheng)、前(qian)饋(kui)(kui)校(xiao)(xiao)(xiao)正(zheng)、復(fu)合校(xiao)(xiao)(xiao)正(zheng)等。如圖8所(suo)示為(wei)系(xi)(xi)(xi)(xi)統(tong)(tong)校(xiao)(xiao)(xiao)正(zheng)裝(zhuang)置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)位置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)示意圖，G（S）為(wei)被控(kong)對(dui)象（主功率電路）；串(chuan)(chuan)聯(lian)校(xiao)(xiao)(xiao)正(zheng)裝(zhuang)置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)一(yi)般連接(jie)在(zai)(zai)G（S）之(zhi)前(qian)，串(chuan)(chuan)接(jie)與系(xi)(xi)(xi)(xi)統(tong)(tong)前(qian)向通(tong)道(dao)之(zhi)中，如G1（S）益(yi)所(suo)示；反饋(kui)(kui)校(xiao)(xiao)(xiao)正(zheng)裝(zhuang)置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)連接(jie)在(zai)(zai)系(xi)(xi)(xi)(xi)統(tong)(tong)局(ju)部(bu)反饋(kui)(kui)通(tong)路之(zhi)中，如G2（S）位置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)所(suo)示；補償給(gei)定量(liang)的(de)(de)前(qian)饋(kui)(kui)校(xiao)(xiao)(xiao)正(zheng)裝(zhuang)置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)接(jie)在(zai)(zai)系(xi)(xi)(xi)(xi)統(tong)(tong)給(gei)定量(liang)之(zhi)后(hou)的(de)(de)前(qian)向通(tong)道(dao)之(zhi)上(shang)，形(xing)成前(qian)饋(kui)(kui)校(xiao)(xiao)(xiao)正(zheng)通(tong)路，如G3（S）位置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)所(suo)示，補償擾動(dong)量(liang)的(de)(de)前(qian)饋(kui)(kui)校(xiao)(xiao)(xiao)正(zheng)裝(zhuang)置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)接(jie)在(zai)(zai)系(xi)(xi)(xi)(xi)統(tong)(tong)可測試的(de)(de)振動(dong)量(liang)之(zhi)后(hou)，形(xing)成一(yi)條附加的(de)(de)通(tong)道(dao)，如G4（S）位置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)所(suo)示。前(qian)饋(kui)(kui)校(xiao)(xiao)(xiao)正(zheng)裝(zhuang)置(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)可以(yi)單獨作用與開環控(kong)制系(xi)(xi)(xi)(xi)統(tong)(tong)，也(ye)可以(yi)作為(wei)反饋(kui)(kui)控(kong)制系(xi)(xi)(xi)(xi)統(tong)(tong)的(de)(de)附加校(xiao)(xiao)(xiao)正(zheng)而(er)組成復(fu)合校(xiao)(xiao)(xiao)正(zheng)控(kong)制系(xi)(xi)(xi)(xi)統(tong)(tong)。

圖8  系統校正裝(zhuang)置位置示意圖

　　七、小結

　　開(kai)關(guan)電源(yuan)系(xi)統通過控制(zhi)電路對主功率電路的控制(zhi)實現電能的變換(huan)。開(kai)關(guan)電源(yuan)系(xi)統有多種控制(zhi)方(fang)式(shi)(shi)，而(er)控制(zhi)方(fang)式(shi)(shi)的核心是校正方(fang)式(shi)(shi)。究竟(jing)選用哪(na)種控制(zhi)方(fang)式(shi)(shi)，系(xi)統如何校正，取決于系(xi)統主功率電路的被控量(liang)的性質(zhi)、抗(kang)擾動性要求、技術實現的方(fang)便性、經濟性要求、環境(jing)使用條件等因素。