Cau 51 Phan loai khai niem may dien dong bo

May dien dong bo la loai may dien xoay chieu ma toc do quay cua roto bang toc do cua tu truong quay trong may.

Phan loai

theochuc nang: May dien dong bo chia ra:may phat, dong co

theo cau tao: Phan quay may dien dong bo chia thanh may dien dong bo co ro to cuc an, va may dien dong bo co roto cuc hien

Cau52  Cau Tao may dien dong bo

May dien dong bo gom hai phan: Phan tinh- xtato,phan quay-roto. Phan ma day quan cua no cam ung ra nhung sdd goi la phan ung, phan tao ra tu truong chinh cho may goi la phan cam. Phan cam co the la phan tinh cung co the la phan quay va phan ung cung vay. Doi voi cac may dien co cong suat trung binh va lon phan cam thuong la phan quay con phan tinh la phan ung

-Phan tinh(xtato)-phan ung

Phan tinh(xtato) cua may dien dong bo la phan ung co cau tao giiong nhu xtato cua may dien khong dong bo, gom loi thep day quan va vo may. Vo may gom nhung la thep KTD day 0,35- 0.5 mm ghep cach dien voi nhau, ben trong co xe ranh de dat day quan. Day quan phan ung cua may dien dong bo ba pha gom 3 cuon day dat cach nhay 120do dien trong khong gian va thuong noi voi nhau thanh hinh sao.

-Phan quay(roto)- phan cam Roto cua may dien dong bo co hai loai tu do hinh thanh hai loai may dien dong bo: Roto cuc an va roto cuc hien

+May dieb dong bo co roto cuc an: Roto cua may dien khong dong bo cuc an lam bang thep hop kim chat luon cao duoc ren thanh khoi hinh tru, phia ngoai co phay ranh de dat day quan. Phan khong phay ranh hinh thanh cuc tu( goi la b\vung rang lon) Voi cach cau tao nhu vaycuc tu cua may phat dien dong bo khong hien ra ro ret nen goi la rotocuc an.May dien khong dong bo loai nay thich hop voi cac dong co lai co toc do cao( may cao toc) 

+May dien dong bo co roto cuc hien( loi): Phan loi thep lam bang thep duc va gia cong thanh khoi tru hoac lang tru cuc tu duoc lam bang thepla ky thuat dien day 1-1.5mm cuc tu hien ra ro ret. Voi cach cau tao nhu trenmay dien dong bo co rot cuc loi thich hop voi vav dong co lai co toc do thap.

Cau 53   Cac thong so dinh muc cua may dien dong bo

: Cong suat dinh muc: La cog suat dau ra cua may tinh toan theo cac dieu kien phat nhiet va lam viec lau dai khong bi hu hong [KW hoac KVA]

-dien ap dinh muc :La dien ap day[V]

-so pha(m)

-tan so[Hz]

-dong dien dinh muc cua xtato va roto[A]

-toc do quay dinh muc[ vong/phut] -he so cong suat(cosφ)

-so do noi day

-cap cach dien cua day

Cau54  NguyenLy hoat dong cua may phat dong bo

Khi quay may phat dien dong bo voi toc do quay bang toc do dinh muc donh thoi nguon kich tu cung duoc cap cho phan cam.Phan ung bien thanh mot lam cham dien. Tu truong phan camcat cac thanh dan cua day quan phan ung lam xuat hien trong cac day quan phan ungcac suc dien dong hinh sin. Neu phan cam co p doi cuc va roto quay voi toc do n thi tan so sdd se la f=p.n/60 tuong tunhu trong may dien dong bo tri so hieu dung cua sdd trong day quan cac pha se la: Eo=4.44f.w.K(dq).Φ trong do: Φ-la thong so duoi moi cuc tu w-la so vong day mot pha K(dq) la he so day quan Neu day quan phan ung cua may dien dong bo la day quan ba pha thi trong day quan se co he thong sdd cam ung ba pha . Khi may dien dong bo mang tai trongday quan phan ung se co he thong don ba pha va se sinh ea tu truong quay voi toc do  n1=60f/p Ta thay toc do tu truong quay dunng bang toc do quaycua rot. Do do may phat dien duoc goi la phat dien dong bo

Cau 55 So do tuong duong,phuong trinh va do thi vector

Khi may dien dong bo lam viec nhu 1 may phat ,suc dien dong Eo=U+r.I+j.x(db)

Vay phuong trinh can bang dien ap cua may dien dong bo la

U=Eo-r.I-j.I.x(db)=Eo-I.z

voi z=r+j.x(db)

Do thi vector cua may phat dien dong bo dc trinh bay:

Cau 56 Dac tinh khong tai

(hinh ve)

Khi may dien dong bo khong tai ,neu ta tang dan dong kick tu I(kt) thi sđ Eo va dien ap tren hai cuc cua may cung tang dan theo. Moi quan he : Eo=f(Ikt) khi n=const goi la dac tinh khong tai. Dac tinh khong tai co dang cua duong cong tu hoa cua vat lieu lam loi thep.

Cau 57  Dac tinh ngoai

Khi may phat dien dong bo mang tai ,dong dien trong day quan phan ung la dong dien phu tai,no gay nen sut ap tren dien tro va dien khang dong bo cua day quan phan ung.Ung voi toc do quay khong doi va dong dien kick tu nhat dinh , dien ap tren 2 cuc cua may phat cang giam thi dong dien cang tang.

Duong dac tinh: 

U=f(I)khi n=const va I(kt)goi la dac tinh ngoai cua may dien dong bo.( I(kt) la I kick tu)

Cau 58 Dac tinh dieu chinh 

(hinh ve)

KHi phu tai cua may dien dong bo tang , muon duy tri dien ap tren 2 cuc cua may phat la khong doi ta phai tang sđ Eo bang cach tang dong kick tu.

MOi quan he: Ikt( kick tu) =j(I)khi n=const va U =const goi la dac tinh dieu chinh cua may phat dien dong bo