Parallel resonant permanent-magnet synchronous generator (PMSG) systems, which consist of a diesel engine, PMSG with a resonant parallel capacitor, and diode full-wave rectifier, may potentially be applied to series hybrid vehicle traction systems owing to their high efficiency and low cost. In general, the power generation in series hybrid vehicle traction systems is controlled using a pulse-width modulated (PWM) converter. However, the power generation in a parallel resonant PMSG hybrid traction system cannot be adjusted using a PWM converter and a new power-generation control method is required. An appropriate power generation control method that considers battery deterioration, number of engine-starts, and fuel economy has not been developed yet. Therefore, this study proposes a power generation control method for parallel resonant PMSG systems applied to series hybrid vehicle traction systems.