Recently, power systems are being operated under increasingly stressed conditions, and the ability to maintain the system stability becomes an issue of concern. A Superconducting Generator (SCG) can be one of the ways to obtain higher stabilities, higher power density and higher efficiencies in the near future power systems. In this paper, SCG with high-response excitation is studied, which is identified to have the potential of improving the system stability by its SMES (Superconducting Magnetic Energy Storage) effect. Taking consideration of the facts that the excitation voltage of a SCG is extremely low meanwhile the field current is considerable high in the normal operation, this paper proposed a new type excitation circuit for SCG that is different with the conventional one, which has introduced a current source PWM converter to automatically regulate the field current instead of the conventional automatic excitation voltage regulation. The validity of the proposed method has been examined by digital simulation studies, and the improving effect of the power system stability by the proposed SCG has been verified as well in this study.