●线电压与相电压的关系 从右图可见t=4- BC CA=P 设=Fm∠0,F2=Vm∠-10,=m∠120 (1-a2)=4+ √3 30 ≤30° 22 根据对称性 ∠30 =-b4=h2(1-a2)=330线电压与相电压的关系 从右图可见 V V V AB A B = − V V V BC B C = − V V V CA C A = − 设 0 , 120 , 120 V V V V V V A pm B pm C pm =  = − =  2 3 3 (1 ) 2 2 3 1 3 3 30 2 2 AB A B A A A A V V V V a V j V j V   = − = − = +         = + =        根据对称性 2 (1 ) 3 30 V V V V a V BC B C B B = − = − =  2 (1 ) 3 30 V V V V a V CA C A C C = − = − =  VAB VBC VCA VA −VA VC −VB −VC VB 30 A I B I CI - VAVC VB N I  A A' Z A ZB ZC N ' B' C ' C B + + − − N