If a current enters the dotted terminal of one coil,the reference polarity of the mutual voltage in the second coil is positive at the dotted terminal of the second coil. Dot convention Alternatively, If a current leaves the dotted terminal of one coil,the reference polar- ity of the mutual voltage in the second coil is negative at the dotted terminal of the second coil. M M 12 di 2=M dt dt (a) (c) M M di 2=-M =M- (b) (d)
Dot convention
例10-4：根据图中“同名端”，写出感应电压表达式。 i M i ,=L d业+M 4=L i di.-M us Ls di
例10-4：根据图中“同名端” ，写出感应电压表达式。 t i M t i u L d d d d 1 2 1 1 t i M t i u L d d d d 2 1 2 2 i1 * * L1 L2 + _ u1 + _ u2 i M 2 * * L1 L2 + _ u1 + _ u2 i M 2 i1 t i M t i u L d d d d 1 2 1 1 t i M t i u L d d d d 2 1 2 2
M + “-1,能-M 山奶 diz+M 42=-L,di 恶 4=L出+M9 1 L L 的 4=-1 d-M脂
t i M t i u L d d d d 1 2 1 1 t i M t i u L d d d d 2 1 2 2 t i M t i u L d d d d 1 2 1 1 t i M t i u L d d d d 2 1 2 2