State-Space Modeling of Dual Active Bridge Converters During Fault Ride-Through Operation

To further improve the fault ride-through ability of three-phase dual active bridge converters, FRT-Buck control mode has been proposed to realize a higher power transmission capacity and a controllable peak current under fault conditions. As the research on FRT-Buck still lacks a rigorous mathematical model, this paper constructs a state-space average model to study the dynamic behaviors of the DAB3 converter. Verified by simulation tests, the state-space average model proposed can accurately depict the behavioral characteristics of dual active bridge converters under both normal working conditions and DC faults. Moreover, the switching from TRI-Buck to FRT-Buck control mode after a fault is simulated. Results show that the state-space average model of FRT-Buck control mode is valid and appears good consistency under low voltage operation.