FFT-Based Steady-State Simulation Method for Active-Bridge Systems

Accurate steady-state modeling is essential for power converter design. A growing class of converters uses all active switching (no diodes), including the dual active bridge, resonant DAB, and wireless power transfer (WPT) systems. The use of all active devices presents an opportunity for rapid frequency domain analysis. The conventional first harmonic approximation (FHA) methods lack accuracy, even in some resonant converters, while time-domain models are computationally intensive and topology-specific. This paper presents a fast Fourier transform (FFT)-based steady-state simulation method that enables fast and accurate prediction of steady-state waveforms, output power, and zero-voltage switching (ZVS) conditions for various topologies. Validation against Simulink, PLECS, and experimental results show that the proposed method achieves over 100* faster computation while maintaining high prediction accuracy.