Hybrid Excitation Doubly Salient Generator (HEDSG) with parallel magnetic circuits is performed in this paper, and the main flux in the machine is determined by the permanent magnet and the field coils. The structure and working principle of the generator are described in detail. In order to build the voltage regulation system of HEDSG, a bidirectional excitation voltage regulator is proposed, which could keep the output voltage of the generator stable by adjusting the field current. The two control loops including excitation current feed-forward and output voltage feedback loops are applied in the voltage regulator. Subsequently, the mathematical model of the voltage regulation system is constructed after the transfer function of the generator is obtained by using system identification method. Moreover, in order to realize the field current bidirectional flow, bipolar pulse width modulation is also applied in the regulator, and the control parameters influencing on the output voltage are analyzed. Lastly, the prototype of bidirectional excitation voltage regulator is designed and theoretical analysis and simulation results are verified by the stable and dynamic experiments.