1)取a为参考点;
Ue = I1*R2 - U1; Ud = Ue + I1*R1;
Ub = I2*R5 + U2; Uc = Ub + I2*R6;
Is1 = I1 - I3;Is2 = I2 + I3;
当 I3 = 0 时(R7开路),可求得 Ub,Uc,Ud,Ue;
那么,Ucd = Uc - Ud = Uoc(开路电压);
等效电阻:Ro =(R1+R2)//(R5+R6);
所以 I = Uoc/(Ro+R7);
2)当求得 I 后,I3 = I 代入上式可求得 Ub,Uc,Ud,Ue;