电机气隙磁密: b=b, tb+.=B Sin a+b sin 3a+ b B b 63 B dIm 2T 0 2 ot. . b  2  0  2 x b  t 电机气隙磁密: 1 3 1 3 sin sin 3 m m b b b B a B a      = + + = + + B 1m 1 b 3 b B 3m