Optimized Coordinated Control of DAB and Three-Phase Inverter Based Cascaded System with Active Damping

As for the dual active bridge (DAB) converter and three-phase inverter based cascaded system, the stability is affected by the interaction between output and input impedance of the two sub-converters. The small-signal models of both DAB and three-phase inverter are firstly derived for stability analysis. Based on the improved Middlebrook criterion, this paper analyzes the difference in impedance characteristics between forward and reverse power flows, and the parameters that affect the stability of system. Then an optimized coordinated control strategy with active damping is proposed to improve the stability under forward power flow. The theoretical analysis results show that the optimized coordinated control can reduce the voltage fluctuation of the DC-link and achieve smooth transitions during sudden power changes and reversals, thereby improving the dynamic response of the system. Furthermore, robustness of the system is enhanced without changing proportional integral (PI) parameters and the circuit hardware. Finally, the optimized coordinated control is compared with conventional control by simulation results.