This paper presents the investigation of a novel capacitor-charging power supply through inertial energy storage of a homopolar inductor alternator (HIA). The structure of a new 18/16-pole HIA is proposed, and we introduce the theory and advantages of HIA. The characteristics of the static magnetic field distributions are calculated by finite-element analysis, and a basic mathematic model of HIA is set up. We propose an efficient and stable capacitor-charging circuit topology to meet the requirements of this system. A functional model of the key device, namely, IGCT, is also established. Finally, we verify its feasibility and advantages through analysis of the system simulation.