A Virtual Inertia Control Strategy for Dual Active Bridge DC-DC Converter

Abstract

Dual active bridge (DAB) DC-DC converter replaces the Buck/Boost circuit for its advantages such as electrical isolation, buck and boost in voltage with high ratio and high-power applications, which has been widely used in energy storage systems. In view of the DC bus voltage vulnerable to power fluctuation in DC micro-grids, a virtual inertial control method for DAB DC-DC converter is proposed in this paper. Analogized with the virtual synchronous generator to be introduced to increase the inertia of the AC microgrid, the virtual inertia control is proposed on the basis of the original dual phase shift control of the converter. When the power in a DC microgrid fluctuates, the energy storage system will provide inertia power support to strengthen the DC microgrid inertia and suppress the DC bus voltage fluctuation. In the proposed inertia control, the first-order inertia link is used to substitute the differential link to avoid high-frequency interference to the input signal. Finally, the DC microgrid model is built by Matlab/Simulink and the time domain simulation is carried out. It has been verified that the control strategy put forward can suppress abrupt change of the DC bus voltage during power fluctuation effectively, but slow down its recovery process. Appropriate control parameters can make the proposed control strategy work better.