Virtual Impedance-based Stabilization of Dual Active Bridge Converter Cascaded with LC Filter

Cascading two individually stable power electronic converters introduces an interaction between their impedances and this causes instability issues to the whole system. To address this problem, this work analyses the stability of a system in which a voltage regulated dual active bridge (DAB) converter is interfaced with an LC filter at its input side and considers an active damping control strategy for stabilization. Under this control scheme, the damping is provided to reshape the effective closed-loop input impedance of DAB through a feedforward loop. In effect, the addition of feedforward control loop virtually introduces a parallel impedance at the interfacing point and compensates the negative impedance behavior caused by the constant power load (CPL) nature of the regulated DAB converter. The feedforward loop stabilizes the input and output voltages of DAB in the presence of external disturbances. This approach is validated through MATLAB/Simulink based simulations.