A Coordinated Control Strategy of Real-Time Compensation for DC Distribution System Based on EtherCAT Communication

In DC distribution system, load switching events and disturbances may cause significant overshoot in DC bus voltage under regular control strategies. To further enhance the dynamic performance of the system, a coordinated control strategy of real-time compensation utilizing EtherCAT communication is proposed in this paper. In this strategy, the state variation command is issued from the master controller to the AC-DC converter. Meanwhile, a compensation value is introduced to the DC-DC converter synchronously based on EtherCAT communication which owns the real-time and high-speed features. Theoretically, it can mitigate the transient process of DC bus voltage during master-regulated state variations. The proposed strategy is verified in a cascaded system of Dual Active Bridge (DAB) and a boost-inductorless single-phase bidirectional isolated AC-DC converter. In order to obtain the precise expression of the compensation, the small signal analysis upon both topology and control loop of the two converters is conducted. Finally, a 3.3kW cascaded experimental platform is built to verify the correctness and effectiveness of the proposed strategy.