【正文】
peed control system Abstract :In the higher demand for performance of speed, if the open loop dc system39。s steady performance does not meet the requirements, can use speed inverse feedback to improve steadystate precision, but although the speed inverse feedback system adopts proportion regulator,it still have off, in order to eliminate static, can use integral regulator to replace proportion regulator. Based on the theoretical analysis of the single closed loop system which is made up of controllable power, the regulator whic h is made up of operational amplifier, a rectifier triggered by thyristor , motor model and tachogenerators module, pare the difference of the open loop system and the closed loop system,the original system and the this paper pares the theory of open loop system and the closedloop system, the difference of primitive system and calibrated system, conclude the optimal model of the dc motor speed control system. Then use this theory to design a practical control system. Key words: steadystatebehaviour stability open loop Closeloop feedback offset 3 3. 電力拖動(dòng)簡(jiǎn)介 電力拖動(dòng)是利用電 動(dòng)機(jī)拖動(dòng)生產(chǎn)機(jī)械的工作機(jī)構(gòu)使之運(yùn)轉(zhuǎn)的一種方法。由于各種生產(chǎn)機(jī)械的工作性質(zhì)和加工工藝不同,對(duì)電動(dòng)機(jī)的控制要求也不同。要使電動(dòng)機(jī)按照生產(chǎn)機(jī)械的要求正常、安全、高效、節(jié)能地運(yùn)轉(zhuǎn),必須配備由一定的電器組成的控制線路。 4. 設(shè)置參數(shù)【自設(shè)】 電動(dòng)機(jī)參數(shù): PN=3KW, nN=1000rpm,UN=220V,IN=17A,Ra= 。主回路總電阻 R=3Ω,電磁時(shí)間常數(shù) Tl=,機(jī)電時(shí)間常數(shù) Tm=。三相橋式整流電路, Ks=45。測(cè)速反饋系數(shù) a=。調(diào)速指標(biāo): D=10, S=5%。 方案的采用 調(diào)節(jié)電樞電壓調(diào)速 電機(jī)降壓起動(dòng)是為了避免高啟動(dòng)轉(zhuǎn)矩和啟動(dòng)電流峰值 ,減小電動(dòng)機(jī)啟動(dòng)過(guò)程的加速轉(zhuǎn)矩和沖擊電流對(duì)工作機(jī)械、供電系統(tǒng)的影響。 特點(diǎn):在保持他勵(lì)直流電動(dòng)機(jī)的磁通為額定值的情況下,電樞回路不串入電阻,將電視兩端的電壓,即電源電壓降低為不同的值時(shí),可以獲得與電動(dòng)機(jī)固有機(jī)械特性相互平行的人為機(jī)械特性,調(diào)速 方向是基速以下,屬于恒轉(zhuǎn)矩調(diào)速方法。只要輸出的電壓是連續(xù)可調(diào)的,即可實(shí)現(xiàn)電動(dòng)機(jī)的無(wú)級(jí)平滑調(diào)速,而且低速運(yùn)行時(shí)的機(jī)械特性基本保持不變。所以得到的調(diào)速范圍可以達(dá)到很高, 而且能實(shí)現(xiàn)可逆運(yùn)行。但對(duì)于可調(diào)的直流電源成本投資相對(duì)其他方法較高。又由于電力電子技術(shù)的發(fā)展,出現(xiàn)了各種的直流調(diào)壓方法,可分為如下兩種: 1)使用晶閘管可控整流裝置的調(diào)速系統(tǒng); 2)使用脈寬調(diào)制的晶體管功率放大器調(diào)速系統(tǒng)。 故系統(tǒng)采用調(diào)節(jié)電樞電壓的調(diào)速方法。這種可以獲得與電動(dòng)機(jī)的固有機(jī)械特性相平行的人為機(jī)械特性,調(diào)速方向是基速以下只要輸出的電壓是連續(xù)可調(diào)的,即可實(shí)現(xiàn)電動(dòng)機(jī)的無(wú)級(jí)平滑調(diào)速,而