電力牽引傳動課程設計三相異步電動機調速系統(tǒng)設計

1、目錄一、概述1、電機概述2、變頻器概述3、三相異步牽引電機變頻調速原理及其種類 3.1變頻調速原理及其機械特性3.2.基頻以下變頻調速3.3.基頻以上變頻調速二、異步電動機在兩相靜止坐標系下的數(shù)學模型三、 異步電動機的仿真模型四、s-function程序五、電機系統(tǒng)模型六、仿真過程及其結果七、總結參考文獻摘 要由于變頻運行下三相異步電動機調速系統(tǒng)具有節(jié)能的重要優(yōu)點,已在國內外工業(yè)生產和日常生活許多領域得到越來越廣泛地應用。目前在變頻調速系統(tǒng)中,隨著電力電子技術及變頻調速技術的迅速發(fā)展,交流調速技術日新月異，新的控制策略不斷涌現(xiàn)，這也使得交流調速開始全面取代直流調速。在交流調速技術中，交流變頻調

2、速以其優(yōu)異的調速性能，高效節(jié)能和廣泛的應用范圍等特點而被國內外人為是最有前途的調速方式。關鍵詞：變頻；三相異步電動機；調速abstractwith the important merit of saving energy for the timing system of three-phase induction motor under the supply of frequency converter, it has been widely used in more and more fields. now, with the rapid development of power elect

3、ronics and frequency-conversion technology.the technology of adjusting speed of ac induction electromotor changes quickly and new control method appears ceaselessly. dc electromotor by the ac induction electromotor is replaced by the ac induction electromotor in wide range. the ac variable frequency

4、 speed regulation is generally acknowledged by the home and abroad that it has a great future with excellent speed regulation, high efficiency saving energy, extensive scope of application and other merit. keywords: frequency converter; three-phase induction motor;change speed一、概述在變頻調速系統(tǒng)中異步電機是一個非線性、

5、強耦合、高階次的控制對象，如果忽略其非線性、強耦合、高階次的條件，近似求出線性單變量動態(tài)結構，得到的控制系統(tǒng)的動態(tài)性能往往不高。要設計具有優(yōu)良動態(tài)性能的異步電機調速系統(tǒng)，必須要深入分析異步電機的動態(tài)數(shù)學模型。本文在分析異步電機數(shù)學模型的基礎上，利用matlab軟件中的simulink對異步電動機進行建模，通過給出異步電動機正弦脈寬調制(spwmsinusoidal pulse width modulation)變頻調速系統(tǒng)的仿真結果來驗證利用這三種方法對異步電機進行建模的可行性。1電機概述1電機作為一種機電能量轉換裝置，在電力工業(yè)各類工礦企業(yè)，農業(yè)國防，交通運輸，日常生活各方面都占有重要地位。

6、隨著科學技術的發(fā)展和社會化大生產的需要，三相基本的電機形式：直流電機，感應電機，同步電機在工業(yè)生產和日常生活中獲得了廣泛的應用。異步電動機的轉速根據(jù)負載的要求，人為的或自動的進行調節(jié)，稱為調速。但出于不同的使用目的，往往對電動機的速度提出不同的要求，如電動車輛，電梯，機床等要求有良好的速度調節(jié)性能；調速也是風機，水泵類負載節(jié)能運行的需要。一般籠型異步電動機的轉速略低于同步轉速，且在負載變化時變化不大，是一種接近于恒速的驅動裝置，其本身的調速性能不佳。因此電動機的調速控制一直是電氣專家學者致力于解決的問題。近年來，直流調速，交流變頻調速隨著技術的進步，性能在不斷改善。直流電動機具有優(yōu)良的調速性能

7、，但它有一個根本的缺點，就是有機械式的整流器整流子和電刷，因此它的維護工作量較大；而且由于機械式整流器的限制，制造大功率高電壓的直流電機比較困難。由于這些原因，限制了直流可調速拖動系統(tǒng)的使用范圍。我們知道，交流異步電動機的轉速n與定子旋轉磁場的速度、轉子的轉差率s有以下關系：式中電源效率，hz，p電動機極對數(shù)；改變電源的頻率，電動機可以調速。變頻調速既適用于同步電動機，又適用異步電動機，是一種高效率的調速方案。2變頻器概述 變頻器是異步電動機調速系統(tǒng)中的關鍵設備。變頻器是利用電力半導體器件的通斷作用將工頻電源變換為另一頻率的電能控制裝置。我們現(xiàn)在使用的變頻器主要采用交直交方式（vvvf變頻或矢

8、量控制變頻），先把工頻交流電源通過整流器轉換成直流電源，然后再把直流電源轉換成頻率、電壓均可控制的交流電源以供給電動機。變頻器的電路一般由整流、中間直流環(huán)節(jié)、逆變和控制4個部分組成。整流部分為三相橋式不可控整流器，逆變部分為igbt三相橋式逆變器，且輸出為pwm波形，中間直流環(huán)節(jié)為濾波、直流儲能和緩沖無功功率。7變頻器實際上就是一個逆變器.它首先是將交流電變?yōu)橹绷麟?然后用電子元件對直流電進行開關.變?yōu)榻涣麟?一般功率較大的變頻器用可控硅.并設一個可調頻率的裝置.使頻率在一定范圍內可調.用來控制電機的轉數(shù).使轉數(shù)在一定的范圍內可調.變頻器廣泛用于交流電機的調速中.變頻調速技術是現(xiàn)代電力傳動技術

9、重要發(fā)展的方向，隨著電力電子技術的發(fā)展，交流變頻技術從理論到實際逐漸走向成熟。變頻器不僅調速平滑，范圍大，效率高，啟動電流小，運行平穩(wěn)，而且節(jié)能效果明顯。因此，交流變頻調速已逐漸取代了過去的傳統(tǒng)滑差調速、變極調速、直流調速等調速系統(tǒng)，越來越廣泛的應用于冶金、紡織、印染、煙機生產線及樓宇、供水空調等領域。3三相異步電動機變頻調速原理及其種類三相異步電動機的調速開始于上世紀50年代末。在電氣傳動領域中，原來只用于恒速傳動的交流電動機實現(xiàn)了調速控制，以取代制造復雜，價格昂貴，維護麻煩的直流電動機。以后，隨著電力電子技術和微型計算機的發(fā)展，再加上現(xiàn)代控制理論向電氣傳動領域的滲透，使得交流調速技術得到了

10、迅速發(fā)展，其設備容量不斷擴大，性能指標及可靠性不斷提高，高性能交流調速系統(tǒng)應用的比例逐年上升，在各工業(yè)部門中，使得交流調速系統(tǒng)逐步取代直流調速系統(tǒng)，以達到節(jié)能，縮小體積、降低成本的目的。根據(jù)三相異步電動機的轉速公式為 式中為異步電動機的定子電壓供電頻率；為異步電動機的極對數(shù)；為異步電動機的轉差率。所以調節(jié)三相異步電動機的轉速有三種方案。異步電動機的變壓變頻調速系統(tǒng)一般簡稱變頻調速系統(tǒng)，由于調速時轉差功率不變，在各種異步電動機調速系統(tǒng)中效率最高，同時性能最好，是交流調速系統(tǒng)的主要研究和發(fā)展方向。3.1變頻調速原理及其機械特性改變異步電動機定子繞組供電電源的頻率，可以改變同步轉速，從而改變轉速。如

11、果頻率連續(xù)可調，則可平滑的調節(jié)轉速，此為變頻調速原理。三相異步電動機運行時，忽略定子阻抗壓降時，定子每相電壓為 式中為氣隙磁通在定子每相中的感應電動勢；為定子電源頻率；為定子每相繞組匝數(shù)；為基波繞組系數(shù)，為每極氣隙磁通量。如果改變頻率，且保持定子電源電壓不變，則氣隙每極磁通將增大，會引起電動機鐵芯磁路飽和，從而導致過大的勵磁電流，嚴重時會因繞組過熱而損壞電機，這是不允許的。因此，降低電源頻率時，必須同時降低電源電壓，已達到控制磁通的目的。對此，需要考慮基頻（額定頻率）以下的調速和基頻以上調速兩種情況。3.2.基頻以下變頻調速18為了防止磁路的飽和，當降低定子電源頻率時，保持為常數(shù)，使氣每極磁通

12、為常數(shù)，應使電壓和頻率按比例的配合調節(jié)。這時，電動機的電磁轉矩為上式對求導，即 ，有最大轉矩和臨界轉差率為由上式可知：當常數(shù)時，在較高時，即接近額定頻率時，隨著的降低，減少的不多；當較低時，較??；相對變大，則隨著的降低，就減小了。顯然，當降低時，最大轉矩不等于常數(shù)。保持常數(shù)，降低頻率調速時的機械特征如圖1所示。這相當于他勵直流電機的降壓調速。圖1 變頻調速的機械特性（a） 基頻以下調速（常數(shù)）（b）基頻以上調速（=常數(shù)）3.3.基頻以上變頻調速在基頻以上變頻調速時，也按比例身高電源電壓時不允許的，只能保持電壓為不變，頻率越高，磁通越低，是一種降低磁通升速的方法，這相當于它勵電動機弱磁調速。保持

13、=常數(shù),升高頻率時，電動機的電磁轉矩為 上式求，得最大轉矩和臨界轉差率為 由于較高，、和比大的多，則上式變?yōu)?因此，頻率越高時，越小，也越小。保持 為常數(shù)，升高頻率調速時的機械特性如圖1（b）所示。二、異步電動機在兩相靜止坐標系下的數(shù)學模型在研究異步電動機的數(shù)學模型時，在文中作如下的假設：(1)忽略空間諧波。設三相繞組對稱(在空間上互差120。電角度)，所產生的磁動勢沿氣隙圓周按正弦規(guī)律分布；(2)忽略磁路飽和，各繞組的自感和互感都是恒定的；(3)忽略鐵芯損耗；(4)不考慮頻率和溫度變化對繞組電阻的影響。異步電動機在靜止坐標系、上的數(shù)學模型為：(1)電壓方程為：(2)磁鏈方程為：(3)轉矩方程

14、為：t (3) e=n p(i11-i11) (3)(4)運動方程為：t e-t l =j*dw/(dt*n p)(4) 式中r 1、r 2、l 1、l 2為定子、轉子電阻和自感，l m為定子、轉子間互感， 為電機轉子角速度；u1、u1為、軸定子電壓，i1、i1、1、1為、軸定子電流及磁鏈，t e為電磁轉矩；t l為負載轉矩；n p為電機極對數(shù)；j 為電機轉動慣量。把靜止軸系下三相/二相變換公式代入上述表達式，得到：將(6)式代入(5)式作非奇異變換，得到以定子電流及定子磁鏈為狀態(tài)的異步電機狀態(tài)方程為：三、 異步電動機的仿真模型基于matlab/simulink的異步電機系統(tǒng)仿真可以利用sim

15、ulink模塊搭建，但是，并非所有的數(shù)學模型都能利用模塊輕易地搭建起來，有的模型更適合于matlab/simulink支持的s一函數(shù)(_)格式，matlab語言或著c等語言格式來描述，構成s一函數(shù)模塊，像標淮的simulink模塊直接調用。上述經過3/2變換的三相異步電機的數(shù)學模型仍是一個高階、非線性、強禍合的多變量系統(tǒng)，用框圖搭建非常煩雜，而且易于出錯。本文的方法是利用matlab格式編寫異步電機的s一函數(shù)來實現(xiàn)電機的建模，其模型簡潔明了、不易出錯。在 ma tl ab/simulink軟件平臺中提供了一個sfuntmpl. m的模板文件，可以利用這個模板文件邀行修改，按自己的需要來構建自己

16、的s一函數(shù)。根據(jù) 數(shù) 學 模型之(5)式，輸人是靜止a,8軸上的定子電壓、,u,以及轉子電角速度.，輸出是靜止a,a軸上的定、轉子電流i,ii,0。根據(jù)matlab語言設計一個名為acmotor_sfun的s-函數(shù)，模型見圖l。當仿真的時候，sfunction模塊直接調用simulink 中自己編寫的acmotor_sfun.m二文件，即可完成m文件所要求的運行功能。m文件的具體程序如下:%兩相靜止坐標系下的電機模型(im) %狀態(tài)變量: x(1)=wr; x(2)=phi_a; x(3)=phi_b; x(4)=i_a; x(5)=i_b; %輸入變量為 u(1)=ua; u(2)=ub;

17、u(3)=uc; 三相輸入電壓; u(4)=t_l 負載轉矩%輸出變量 sys(1)=wr; sys(2)=i_a; sys(3)=i_b; sys(4)=i_c; sys(5)=te function sys,x0,str,ts = motor(t, x, u,flag, rs, rr, ls, lr, lm, j, np) switch flag, case 0, sys, x0, str, ts=mdlinitializesizes; case 1, sys=mdlderivatives(t, x, u, rs, ls, rr, lr, lm, j, np); case 2, 9, sy

18、s= ; case 3, sys=mdloutputs(t,x,rs, ls, rr, lr, lm, j, np); case 4, sys=mdlgettimeofnextvarhit(t,x,u); otherwise error(unhandled flag = ,num2str(flag); end % 初始化 function sys,x0,str,ts=mdlinitializesizes sizes = simsizes; sizes.numcontstates = 5; sizes.numdiscstates = 0; sizes.numoutputs = 5; sizes.

19、numinputs = 3; sizes.dirfeedthrough = 1; sizes.numsampletimes = 1; sys = simsizes(sizes); x0 = 0; str = ; ts = 0 0; % 微分 function sys=mdlderivatives(t,x,u,rs,ls,rr,lr,lm,j,np) delta=1-lm*lm/(ls*lr); %狀態(tài)方程(x(1)=wr,x(2)=phi_a,x(3)=phi_b,x(4)=i_a,x(5)=i_b) dx(1)=(np2*lm/(j*lr)*(x(2)*x(5)-x(3)*x(4)-np*u

20、(3)/j; dx(2)=-(rr/lr)*x(2)-x(1)*x(3)+(rr/lr)*lm*x(4); dx(3)=-(rr/lr)*x(3)+x(1)*x(2)+(rr/lr)*lm*x(5); dx(4)=lm*rr/(delta*ls*lr*lr)*x(2)+lm/(delta*ls*lr)*x(1)*x(3)-(lm*lm*rr+lr*lr*rs)/(delta*ls*lr*lr)*x(4)+u(1)/(delta*ls); dx(5)=lm*rr/(delta*ls*lr*lr)*x(3)-lm/(delta*ls*lr)*x(1)*x(2)-(lm*lm*rr+lr*lr*rs

21、)/(delta*ls*lr*lr)*x(5)+u(2)/(delta*ls); sys=dx;%sys(1)=(np*np*lm/(j*lr)*(sys(2)*sys(5)-sys(3)*sys(4)-u(4)/j; % 微分結束 % 輸出 function sys=mdloutputs(t,x,rs, ls, rr, lr, lm, j, np)sys(1)=x(1); %wr sys(2)=sqrt(2/3)*x(4); %i_a sys(3)=-sqrt(1/6)*x(4)+sqrt(1/2)*x(5); %i_b sys(4)=-sqrt(1/6)*x(4)-sqrt(1/2)*x(

22、5); %i_csys(5)=np*(lm/lr)*(x(2)*x(5)-x(3)*x(4); %te % 輸出結束 % 終止 function sys=mdlterminate(t, x, u) sys = ; function sys=mdlgettimeofnextvarhit(t,x,u) sampletime = 200; % example, set the next hit to be one second later. sys = t + sampletime; % end mdlgettimeofnextvarhit 四、s-function程序function a,b,c,

23、d,k,x0 = motor(par,ts,aux)%motor ode file representing the dynamics of a motor.% a,b,c,d,k,x0 = motor(tau,ts,g)% returns the state space matrices of the dc-motor with% time-constant tau (tau = par) and known static gain g. the sample% time is ts.% this file returns continuous-time representation if

24、input argument ts% is zero. if ts0, a discrete-time representation is returned. to make% the idgrey model that uses this file aware of this flexibility, set the% value of structure.fcntype property to cd. this flexibility is useful% for conversion between continuous and discrete domains required for

25、% estimation and simulation.% see also idgrey, iddemo7. % l. ljung% copyright 1986-2011 the mathworks, inc.% $revision: .2.1 $ $date: 2011/12/27 15:42:57 $ t = par(1);g = aux(1); a = 0 1;0 -1/t;b = 0;g/t;c = eye(2);d = 0;0;k = zeros(2);x0 = 0;0;if ts0 % sample the model with sample time ts s

26、 = expm(a b*ts; zeros(1,3); a = s(1:2,1:2); b = s(1:2,3);end五、電機系統(tǒng)模型六、仿真過程及其結果（1）20hz電流20hz電流整體20hz電壓設置20hz轉速（2）50hz電流50hz電流整體待添加的隱藏文字內容250hz轉速50hz電壓設置六、總結本文討論了基于兩相靜止坐標系下的三相異步交流電機在matlab/simulink環(huán)境下的仿真，介紹了s一function建模的方法，其特點是編程容易，模型直觀，沒有煩瑣的框圖。然后以轉動慣量的大小變化對電機啟動時的影響為例，進行電機模型的仿真，從仿真結果可以看出所建模型符含實際異步電機的運

27、行特性，驗證了設計模型的正確性，為進一步基于dsp的矢量控制變頻調速系統(tǒng)的研究奠定基礎。參考文獻1陳建業(yè)，電力電子電路的計算機仿真，北京：清華大學出版社，20052陳剛，軟開關雙向dc/dc變換器的研究，浙江大學博士學位論文，20013張國安，朱忠尼，新型推挽式移相式軟開關拓撲研究，電工技術雜志，1998（1）4伊林林，軟開關pwm 雙向d c / d c 變換器的研5百度employment tribunals sort out disagreements between employers and employees.you may need to make a claim to an e

28、mployment tribunal if: you dont agree with the disciplinary action your employer has taken against you your employer dismisses you and you think that you have been dismissed unfairly.for more information about dismissal and unfair dismissal, seedismissal.you can make a claim to an employment tribuna

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30、bunal within three months of the date when the event you are complaining about happened. if your application is received after this time limit, the tribunal will not usually accept it.if you are worried about how the time limits apply to you, take advice from one of the organisations listed underfur

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32、unal, you should get help straight away from one of the organisations listed underfurther help.if you are being represented by a solicitor at the tribunal, they may ask you to sign an agreement where you pay their fee out of your compensation if you win the case. this is known as adamages-based agre

33、ement. in england and wales, your solicitor cant charge you more than 35% of your compensation if you win the case.if you are thinking about signing up for a damages-based agreement, you should make sure youre clear about the terms of the agreement. it might be best to get advice from an experienced

34、 adviser, for example, at a citizens advice bureau. to find your nearest cab, including those that give advice by e-mail, click onnearest cab.for more information about making a claim to an employment tribunal, seeemployment tribunals.the (lack of) air up there watch mcayman islands-based webb, the

35、head of fifas anti-racism taskforce, is in london for the football associations 150th anniversary celebrations and will attend citys premier league match at chelsea on sunday.i am going to be at the match tomorrow and i have asked to meet yaya toure, he told bbc sport.for me its about how he felt an

36、d i would like to speak to him first to find out what his experience was.uefa hasopened disciplinary proceedings against cskafor the racist behaviour of their fans duringcitys 2-1 win.michel platini, president of european footballs governing body, has also ordered an immediate investigation into the

37、 referees actions.cska said they were surprised and disappointed by toures complaint. in a statement the russian side added: we found no racist insults from fans of cska.age has reached the end of the beginning of a word. may be guilty in his seems to passing a lot of different life became the appea

38、rance of the same day; may be back in the past, to oneself the paranoid weird belief disillusionment, these days, my mind has been very messy, in my mind constantly. always feel oneself should go to do something, or write something. twenty years of life trajectory deeply shallow, suddenly feel somet

39、hing, do it.一字開頭的年齡已經到了尾聲?；蛟S是愧疚于自己似乎把轉瞬即逝的很多個不同的日子過成了同一天的樣子；或許是追溯過去，對自己那些近乎偏執(zhí)的怪異信念的醒悟，這些天以來，思緒一直很凌亂，在腦海中不斷糾纏。總覺得自己自己似乎應該去做點什么，或者寫點什么。二十年的人生軌跡深深淺淺，突然就感覺到有些事情，非做不可了。the end of our life, and can meet many things really do?而窮盡我們的一生，又能遇到多少事情是真正地非做不可？during my childhood, think lucky money and new clothes

40、are necessary for new year, but as the advance of the age, will be more and more found that those things are optional; junior high school, thought to have a crush on just means that the real growth, but over the past three years later, his writing of alumni in peace, suddenly found that isnt really

41、grow up, it seems is not so important; then in high school, think dont want to give vent to out your inner voice can be in the high school children of the feelings in a period, but was eventually infarction when graduation party in the throat, later again stood on the pitch he has sweat profusely, l

42、ooked at his thrown a basketball hoops, suddenly found himself has already cant remember his appearance.童年時，覺得壓歲錢和新衣服是過年必備，但是隨著年齡的推進，會越來越發(fā)現(xiàn)，那些東西根本就可有可無；初中時，以為要有一場暗戀才意味著真正的成長，但三年過去后，自己心平氣和的寫同學錄的時候，突然就發(fā)現(xiàn)是不是真正的成長了，好像并沒有那么重要了；然后到了高中，覺得非要吐露出自己的心聲才能為高中生涯里的懵懂情愫劃上一個句點，但畢業(yè)晚會的時候最終還是被梗塞在了咽喉，后來再次站在他曾經揮汗如雨的球場，看著

43、他投過籃球的球框時，突然間發(fā)現(xiàn)自己已經想不起他的容顏。originally, this world, can produce a chemical reaction to an event, in addition to resolutely, have to do, and time.原來，這個世界上，對某個事件能產生化學反應的，除了非做不可的堅決，還有，時間。a persons time, your ideas are always special to clear. want, want, line is clear, as if nothing could shake his. als

44、o once seemed to be determined to do something, but more often is he backed out at last. dislike his cowardice, finally found that there are a lot of love, there are a lot of miss, like shadow really have been doomed. those who do, just green years oneself give oneself an arm injection, or is a self

45、-righteous spiritual.一個人的時候，自己的想法總是特別地清晰。想要的，不想要的，界限明確，好像沒有什么可以撼動自己。也曾經好像已經下定了決心去做某件事，但更多的時候是最后又打起了退堂鼓。嫌惡過自己的怯懦，最終卻發(fā)現(xiàn)有很多緣分，有很多錯過，好像冥冥之中真的已經注定。那些曾經所謂的非做不可，只是青蔥年華里自己給自己注射的一支強心劑，或者說，是自以為是的精神寄托罷了。at the moment, the sky is dark, the air is fresh factor after just rained. suddenly thought of blue plaid sh

46、irt; those were broken into various shapes of stationery; from the corner at the beginning of deep friendship; have declared the end of the encounter that havent start planning. those years, those days of do, finally, like youth, will end in our life.此刻，天空是陰暗的，空氣里有著剛下過雨之后的清新因子。突然想到那件藍格子襯衫；那些被折成各種各樣形

47、狀的信紙；那段從街角深巷伊始的友誼；還有那場還沒有開始就宣告了終結的邂逅計劃那些年那些天的非做不可，終于和青春一樣，都將在我們的人生中謝幕。baumgartner the disappointing news: mission aborted. r plays an important role in this mission. starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud c

48、over. the balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. it will climb higher than the tip of mount everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) a