傳統的(de)(de)鼠(shu)籠(long)(long)式(shi)異步(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)起(qi)(qi)(qi)(qi)、制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)動(dong)(dong)(dong)控(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)方(fang)(fang)式(shi)一(yi)(yi)般有四種(zhong)(zhong)，即定子(zi)回(hui)路(lu)串電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)起(qi)(qi)(qi)(qi)動(dong)(dong)(dong)，Y/△起(qi)(qi)(qi)(qi)動(dong)(dong)(dong)，自(zi)耦變壓器(qi)(qi)(qi)(qi)(qi)起(qi)(qi)(qi)(qi)動(dong)(dong)(dong)和延邊(bian)三(san)(san)角形(xing)起(qi)(qi)(qi)(qi)動(dong)(dong)(dong);制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)動(dong)(dong)(dong)方(fang)(fang)式(shi)有三(san)(san)種(zhong)(zhong)，反接(jie)(jie)制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)動(dong)(dong)(dong)，能耗制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)動(dong)(dong)(dong)和電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)動(dong)(dong)(dong)，其(qi)中(zhong)任何一(yi)(yi)種(zhong)(zhong)起(qi)(qi)(qi)(qi)，、制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)動(dong)(dong)(dong)控(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)方(fang)(fang)式(shi)的(de)(de)實現通(tong)常(chang)由繼電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)-接(jie)(jie)觸(chu)(chu)器(qi)(qi)(qi)(qi)(qi)控(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)系統來完成。下(xia)面就以定子(zi)回(hui)路(lu)串電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)降壓起(qi)(qi)(qi)(qi)動(dong)(dong)(dong)和反接(jie)(jie)制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)動(dong)(dong)(dong)為(wei)例，分(fen)析由繼電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)-接(jie)(jie)觸(chu)(chu)器(qi)(qi)(qi)(qi)(qi)實現的(de)(de)鼠(shu)籠(long)(long)式(shi)異步(bu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)的(de)(de)起(qi)(qi)(qi)(qi)、制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)動(dong)(dong)(dong)控(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)。如(ru)圖1所示，此控(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)含三(san)(san)個接(jie)(jie)觸(chu)(chu)器(qi)(qi)(qi)(qi)(qi)和一(yi)(yi)個中(zhong)間繼電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)線(xian)(xian)圈(quan)，12個觸(chu)(chu)點(dian)。起(qi)(qi)(qi)(qi)動(dong)(dong)(dong)時(shi)，KM2、KM3線(xian)(xian)圈(quan)均處于斷(duan)(duan)開(kai)狀態(tai)，按(an)下(xia)起(qi)(qi)(qi)(qi)動(dong)(dong)(dong)按(an)鈕SB1，KM1線(xian)(xian)圈(quan)通(tong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)并自(zi)鎖，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)串電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)減(jian)壓起(qi)(qi)(qi)(qi)動(dong)(dong)(dong)。當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)轉速上(shang)升到(dao)某一(yi)(yi)定值時(shi)(此值為(wei)速度(du)繼電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)KS1的(de)(de)整定值，可調節，如(ru)調至100r/min時(shi)動(dong)(dong)(dong)作)，速度(du)繼電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)KS1的(de)(de)常(chang)開(kai)觸(chu)(chu)點(dian)閉和，中(zhong)間繼電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)KA通(tong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)并自(zi)鎖，KA的(de)(de)常(chang)開(kai)觸(chu)(chu)點(dian)接(jie)(jie)通(tong)接(jie)(jie)觸(chu)(chu)器(qi)(qi)(qi)(qi)(qi)線(xian)(xian)圈(quan)KM3，KM3的(de)(de)主(zhu)觸(chu)(chu)點(dian)在主(zhu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)短(duan)接(jie)(jie)定子(zi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)R，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)轉速上(shang)升至給定值時(shi)投入穩定運行。制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)動(dong)(dong)(dong)時(shi)，按(an)下(xia)停機(ji)(ji)按(an)鈕SB2，KM1線(xian)(xian)圈(quan)斷(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，其(qi)主(zhu)觸(chu)(chu)點(dian)斷(duan)(duan)開(kai)三(san)(san)相電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源;控(kong)(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)常(chang)開(kai)觸(chu)(chu)點(dian)斷(duan)(duan)開(kai)，KM3失電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，限流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)串入;常(chang)閉觸(chu)(chu)點(dian)閉合(he)，接(jie)(jie)通(tong)反接(jie)(jie)制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)動(dong)(dong)(dong)接(jie)(jie)觸(chu)(chu)器(qi)(qi)(qi)(qi)(qi)KM2，對調兩(liang)相電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源相序(xu)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)處于反接(jie)(jie)制(zhi)(zhi)(zhi)(zhi)(zhi)(zhi)動(dong)(dong)(dong)狀態(tai)。當轉速下(xia)降至某一(yi)(yi)定值時(shi)(比如(ru)100r/min),KS1常(chang)開(kai)觸(chu)(chu)點(dian)斷(duan)(duan)開(kai)KA，繼而(er)斷(duan)(duan)開(kai)KM2，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)失電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，迅速停機(ji)(ji)。
這種傳統的繼電器接觸器控制方式控制邏輯清晰，采用機電合一的組合方式便于普通機類或電類技術人員維修，但由于使用的電氣元件體積大、觸點多、故障率大，因此，運行的可靠性較低。隨著PLC技術的發展，使用PLC進行電機的運行控制已成為必然趨勢。
2. 采(cai)用PLC實現鼠(shu)籠(long)式(shi)異(yi)步(bu)電動(dong)(dong)器(qi)起、制(zhi)(zhi)(zhi)動(dong)(dong)控(kong)制(zhi)(zhi)(zhi)可編程序控(kong)制(zhi)(zhi)(zhi)器(qi)是在(zai)繼電器(qi)控(kong)制(zhi)(zhi)(zhi)和計算(suan)機控(kong)制(zhi)(zhi)(zhi)的(de)(de)(de)基礎上開發的(de)(de)(de)產(chan)品，自60年(nian)代末，美國(guo)首先研制(zhi)(zhi)(zhi)和使(shi)用可編程控(kong)制(zhi)(zhi)(zhi)器(qi)以后，世界各國(guo)特(te)別(bie)是日本和聯(lian)邦德國(guo)也相繼開發了各自的(de)(de)(de)PLC(programmable logic controller)，因此，與傳統(tong)的(de)(de)(de)繼電器(qi)接(jie)觸(chu)器(qi)控(kong)制(zhi)(zhi)(zhi)系(xi)統(tong)相比(bi)較(jiao)，筆(bi)者認為采(cai)用PLC實現鼠(shu)籠(long)式(shi)異(yi)步(bu)電動(dong)(dong)機起制(zhi)(zhi)(zhi)動(dong)(dong)控(kong)制(zhi)(zhi)(zhi)是最(zui)明(ming)智的(de)(de)(de)選擇。下面就是筆(bi)者設計的(de)(de)(de)采(cai)用PLC實現的(de)(de)(de)鼠(shu)籠(long)式(shi)異(yi)步(bu)電動(dong)(dong)機起制(zhi)(zhi)(zhi)動(dong)(dong)控(kong)制(zhi)(zhi)(zhi)電路的(de)(de)(de)接(jie)線(xian)圖(tu)(tu)、梯形圖(tu)(tu)和指令程序，
PLC控制邏輯與傳統的繼電器接觸器控制系統基本一致，其工作過程如下：
:起動(dong)(dong)時(shi)，按下起動(dong)(dong)按鈕SB1,X400常(chang)(chang)(chang)(chang)(chang)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)觸(chu)(chu)(chu)(chu)(chu)點閉(bi)(bi)(bi)(bi)合，Y430線(xian)(xian)(xian)(xian)圈(quan)(quan)接(jie)(jie)通(tong)并自(zi)鎖，KM1線(xian)(xian)(xian)(xian)圈(quan)(quan)接(jie)(jie)通(tong)，主觸(chu)(chu)(chu)(chu)(chu)頭(tou)吸合，電(dian)(dian)動(dong)(dong)機(ji)串入限(xian)流(liu)電(dian)(dian)阻(zu)R開(kai)(kai)(kai)(kai)(kai)(kai)(kai)始(shi)起動(dong)(dong)，同(tong)時(shi)Y430的(de)兩(liang)對(dui)常(chang)(chang)(chang)(chang)(chang)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)觸(chu)(chu)(chu)(chu)(chu)點閉(bi)(bi)(bi)(bi)合，當電(dian)(dian)動(dong)(dong)機(ji)轉(zhuan)(zhuan)速上升到(dao)某(mou)一(yi)定(ding)(ding)值時(shi)，KS1的(de)常(chang)(chang)(chang)(chang)(chang)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)觸(chu)(chu)(chu)(chu)(chu)點閉(bi)(bi)(bi)(bi)合，X402常(chang)(chang)(chang)(chang)(chang)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)觸(chu)(chu)(chu)(chu)(chu)點閉(bi)(bi)(bi)(bi)合，M100線(xian)(xian)(xian)(xian)圈(quan)(quan)接(jie)(jie)通(tong)并自(zi)鎖，M100的(de)一(yi)對(dui)常(chang)(chang)(chang)(chang)(chang)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)觸(chu)(chu)(chu)(chu)(chu)點接(jie)(jie)通(tong)Y432的(de)線(xian)(xian)(xian)(xian)圈(quan)(quan)，KM3線(xian)(xian)(xian)(xian)圈(quan)(quan)有電(dian)(dian)主觸(chu)(chu)(chu)(chu)(chu)頭(tou)吸合，短接(jie)(jie)起動(dong)(dong)電(dian)(dian)阻(zu)，電(dian)(dian)機(ji)轉(zhuan)(zhuan)速上升至給定(ding)(ding)值時(shi)投入穩定(ding)(ding)運行(xing)。制(zhi)動(dong)(dong)時(shi)，按下停(ting)機(ji)按鈕SB2，X401常(chang)(chang)(chang)(chang)(chang)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)觸(chu)(chu)(chu)(chu)(chu)點斷(duan)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)Y430線(xian)(xian)(xian)(xian)圈(quan)(quan)，使(shi)KM1失電(dian)(dian)釋放，而(er)Y430的(de)常(chang)(chang)(chang)(chang)(chang)閉(bi)(bi)(bi)(bi)觸(chu)(chu)(chu)(chu)(chu)點接(jie)(jie)通(tong)Y431線(xian)(xian)(xian)(xian)圈(quan)(quan)，制(zhi)動(dong)(dong)用(yong)的(de)接(jie)(jie)觸(chu)(chu)(chu)(chu)(chu)器KM2線(xian)(xian)(xian)(xian)圈(quan)(quan)通(tong)電(dian)(dian)，對(dui)調(diao)兩(liang)相電(dian)(dian)源的(de)相序，電(dian)(dian)動(dong)(dong)機(ji)處(chu)于(yu)反接(jie)(jie)制(zhi)動(dong)(dong)狀態。與此同(tong)時(shi)，Y430的(de)常(chang)(chang)(chang)(chang)(chang)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)觸(chu)(chu)(chu)(chu)(chu)點斷(duan)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)Y432的(de)線(xian)(xian)(xian)(xian)圈(quan)(quan)，KM3失電(dian)(dian)釋放，串入電(dian)(dian)阻(zu)R限(xian)制(zhi)制(zhi)動(dong)(dong)電(dian)(dian)流(liu)。當電(dian)(dian)動(dong)(dong)機(ji)轉(zhuan)(zhuan)速迅速下降至某(mou)一(yi)定(ding)(ding)值時(shi)，KS1常(chang)(chang)(chang)(chang)(chang)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)觸(chu)(chu)(chu)(chu)(chu)點斷(duan)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)，X402常(chang)(chang)(chang)(chang)(chang)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)觸(chu)(chu)(chu)(chu)(chu)點斷(duan)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)M100的(de)線(xian)(xian)(xian)(xian)圈(quan)(quan)，M100的(de)常(chang)(chang)(chang)(chang)(chang)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)觸(chu)(chu)(chu)(chu)(chu)點斷(duan)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)Y431線(xian)(xian)(xian)(xian)圈(quan)(quan)，KM2失電(dian)(dian)釋放，電(dian)(dian)動(dong)(dong)機(ji)很(hen)快停(ting)下來。過載(zai)時(shi)，熱繼(ji)電(dian)(dian)器FR常(chang)(chang)(chang)(chang)(chang)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)觸(chu)(chu)(chu)(chu)(chu)點閉(bi)(bi)(bi)(bi)合，X403的(de)兩(liang)對(dui)常(chang)(chang)(chang)(chang)(chang)閉(bi)(bi)(bi)(bi)觸(chu)(chu)(chu)(chu)(chu)點斷(duan)開(kai)(kai)(kai)(kai)(kai)(kai)(kai)Y430和M110的(de)線(xian)(xian)(xian)(xian)圈(quan)(quan)，從(cong)而(er)使(shi)KM1或KM2失電(dian)(dian)釋放，起到(dao)過載(zai)保護作用(yong)。
PLC與繼電器接觸器控制系統的比較通過對鼠籠式異步電動機起制動的傳統控制方法和PLC控制方法的比較，從某種意義上看，PLC控制是從繼電器接觸器控制發展而來的。兩者既有相似性又有很多不同處。
3.1 二種方案的不同點
(1)PLC內部大部分采用“軟”邏輯
繼電器接觸器控制全部用硬器件、硬觸點和“硬”線連接，為全硬件控制;PLC內部大部分采用“軟”電器、“軟”接點和“軟”線連接，為軟件控制；
(2) PLC控制系統結構緊湊
繼電器接觸器控制系統使用電器多，體積大且故障率大;PLC控制系統結構緊湊，使用電器少，體積小；
(3) PLC內部全為“軟接點”動作快
電器接觸器控制全為機械式觸點，動作慢，弧光放電嚴重;PLC內部全為“軟接點”動作快；
(4) PLC控制功能改變極其方便
繼電器接觸器控制功能改變，需拆線接線乃至更換元器件，比較麻煩;PLC控制功能改變，一般只需修改程序便可，極其方便；
(5) PLC控制系統制造周期短
PLC控制系統由于結構簡單緊湊，基本為軟件控制，因此設計、施工與調試比繼電器接觸器控制系統周期短。
此外，由于PLC技術是計算機控制的基礎上發展而來，因此，它的軟硬件設置上有著傳統的繼電器接觸器控制無法比擬的優勢，工作可靠性極高。
3.2 PLC方案的設計要點
(1) 設置濾波
在PLC中一般都在輸入輸出接口處設置π形濾波器，它不僅可濾除來自外界的高頻干擾，而且還可減少內部模塊之間信號的相互干擾；
(2) 設有隔離
在PLC系統中CPU和各I/O回路(主要指數字口)幾乎都設有光耦合器作隔離，以防止干擾或可能損壞CPU等；
(3) 設置屏蔽
屏蔽有兩類:一類是對變壓器采取磁場和電場的雙重屏蔽，這時要用既導磁又導電的材料作為屏蔽層;另一類是對CPU和編程器等模塊僅作電磁場的屏蔽，此時可用導電的金屬材料作屏蔽層；
(4) 采用模塊式結構
PLC通常采用積木式結構，這便于用戶檢修和更換模板，同時在各模板上都設有故障檢測電路，并用相應的指示器標志它的狀態，使用戶能迅速確定故障的位置；
(5) 設有聯鎖功能
PLC中個各輸出通道之間設有聯鎖功能。以防止各被控對象之間誤動作可能造成的事故；
(6) 設置環境檢測和診斷電路
這部分電路負責對PLC的運行環境(例如電網電壓、工作溫度、環境的濕度等)進行檢測，同時也完成對PLC中各模塊工作狀態的監測。這部分電路往往是與軟件相配合工作的，以實現故障自動診斷和預報；
(7) 設置Watchdog電路
PLC中的這種電路是專門監視PLC運行進程是否按預定的順序進行，如果PLC中發生故障或用戶程序區受損，則因CPU不能按預定順序(預定時間間隔)工作而報警；
(8) PLC的輸入、輸出控制簡單
PLC是以掃描方式進行工作的，即PLC對信號的輸入、數據的處理和控制信號的輸出，分別在一個掃描周期內的不同時間間隔里，以批處理方式進行，這不僅使用戶編程簡單、不易出錯，而且也使PLC的工作不易受到外界干擾的影響;同時PLC所處理的數據比較穩定，從而減少了處理中的錯誤；另外，PLC的輸入、輸出的控制較簡單，不容易產生由于時序不合適而造成的問題。
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