In this study the authors present the contribution of the thyristor excitation structure in combination with a multivariable H∞ controller. The thyristor bridge is supplied by a wound eld synchronous machine (WFSM). A complete modeling of the excitation structure will be presented. The linearization of the feedback control is realized without approximation. The design of the multi input single output H∞ voltage controller will be also included. In addition, the implementation in real time domain will allow us to show the ef ciency of the proposed structure as regards the reference tracking and perturbation rejection.Index Terms-H∞ control, AC generator excitation, state space modeling, thyristor recti er.NOMENCLATURE v dp , v qp SG terminal voltages in dq frame. i dp , i qp SG armature currents in dq frame. v f , i f voltage and current of the main eld winding. L d , L q SG direct and transverse stator inductances. L D , L Q SG direct and transverse dampers inductances. L f SG main eld inductance. M sf SG mutual inductance between direct stator winding and main eld one. M f D SG mutual inductance between main eld and direct damper. M sD , M sQ SG mutual inductance between direct stator winding and direct/transverse damper windings. R s , R f SG stator resistance, SG main eld resistance. R D , R Q SG direct and transverse damper resistances. ω ep SG electrical angular speed.