One of the main keys for modern high efficiency power converters for traction applications is implementation of soft-switching technology. Moreover, its control technologies seeks to increase the power density with high frequency. However, this kind of architecture, involving high frequency resonance, is too complex for the real-time simulation with a limited bandwidth. This paper proposes a reduced-order model for this soft-switching circuit by time-domain analysis approach which exhibits a valuable characteristic for the real-time simulation. A variable matrix and subsystem methods are used to solve interface voltages/current from the torn system. Successful implementation of the proposed model on a field programmable gate array (FPGA) device is reported and its application for traction power supply system is implemented with a hardware in the loop (HIL) test. Fixed point operators are used to ensure good accuracy and low computational latency. Comparison between the experiment results and traction auxiliary analysis shows its stability.