1.瞬时值表达式 B ua(t)=v2U sin( ot +y) L uB 1(t)=√2Usi(t+y-120°) XY2l2(1)=√2sm(ot+y-240) J/sn(Ot+y+120°) 20211/272021/1/27 4 1. 瞬时值表达式 2 sin( 120 ) ( ) 2 sin( 240 ) ( ) 2 sin( 120 ) ( ) 2 sin( ) o o C o B A = + + = + − = + − = + U t ψ u t U t ψ u t U t ψ u t U t ψ w w w w A + – X uA B + – Y uB C + – Z uC