Gio trnh My đin Trang 21 1.7 QUAN HÊ ̣ ĐIÊ ̣ N TƯ ̀ TRONG MA ́ Y ĐIÊ ̣ N MÔ ̣ T CHIÊ ̀ U 1.7.1 Sc đin đng cm ng ca dây qun phn ng:     : E td = B td . l . v = 2p  n ( v )   : E td :          B tb :         . 2p:     . :     /  ( Wb ). n:   (/giây ). : N:     . 2a:      E  :               .     /: n a pN E ö  60 : C E = a pN 60 :    E ư = C E .  . n                                 .       .                                                  .         .   , M             ,           . - I  E  - + + I t n G Gio trnh My đin Trang 22   , M       ,           .              I    .  1.7.2 Momen điê ̣ n tư ̀ :                   : f = B tb . i  . l B tb :         . i  : . a I i ö ö 2  l:           . I  : .           : M  = f . r . N = B tb . N . 22 öö D .l. a I r : . 2 ö D r  ( D  :       ). B tb = l.     .p D ö 2  => ö ö ñt I a pNp .l. a I .N. l. M       22 2 2  M = a pN  2 :    M đt = C M .  . I ư 1.7.3 Công suâ ́ t điê ̣ n tư ̀ : P  = M  .  :      60 2 n    n:    Thay M  = a pN  2 .  . I  + -  I I  G Gio trnh My đin Trang 23 P  = a pN  2 .  . I  . a pNn 6060 2   .  . n . I  = E  . I  P đt = E ư . I ư 1.7.4 Qu trnh năng lưng v cc phương trnh cân bng: a) Đi vi my pht đin: P 1 :   . P t :       P  + F Fe :   +     P  :         . P  :      P 2 :   .   : 1 1 2  P P      : P 2 = P   P  chia 2   : UI  = E  I  - öö R.I 2 U = E ư – I ư .R ư                    . E  :       ,   M 1 :    M  :     M 0 :    0 = P  + P Fe M 1 = M đt + M 0  . P 1 P dt P 2 P t P  P  + P Fe Gin đ năng lưng ca my pht 1 chiều  I  I  + - E  R  + - U Gio trnh My đin Trang 24 b) Đng cơ đin P 1 :     . P 2 : . P 1 = P  + P t + P  U( I  + I t ) = E  .I  + UI t + öö RI 2 U = E ư + I ư R ư          . E            ,     M 2 :  M  :     M 0 :    M 2 = M đt – M 0              . 1.7.5 Tnh thun nghch trong my đin mt chiu:                 ,    .       : E  , I   M     M      : E  , I     M   P 1 P dt P 2 P t P  P  + P Fe Gin đ năng lưng ca ĐC 1 chiều I  I  + - E  R  + - U N S +  E  , I  n M  N S +  E  , I  n, M t  +   Gio trnh My đin Trang 25 : 0   ö ö ö R UE I   > U     (  ) ( n )         < U  I  < 0  (   ), E       .       M        ( M       ).            . 1.7.6 V d : Bi 1 :                    = 1000 /           0 = 222 V.                  = 220        ?.                         : 0ñm0.ñmE E 0.ñm 0 n n nC nC E E         = 220  : n  = n phuùt/voøng990 222 220 1000 E E 0 ñm.0  Bi 2 :                   = 5,5 kW, U  = 110 V, I  = 58 A (              t ), n  = 1470 /.         = 0,15  ,             t = 137  ,          2 V2U tx  .        , ? .            ,           . - I  E  - + + I t n G Gio trnh My đin Trang 22  .    Thay M  = a pN  2 .  . I  + -  I I  G Gio trnh My đin Trang 23 P  = a pN  2 .  . I  . a pNn 6060 2   .