AN IMPROVED MODELLING AND DYNAMIC CONTROL OF THE DUAL ACTIVE BRIDGE CONVERTER FOR FAST BATTERY CHARGING OF ELECTRIC VEHICLES

This paper investigates the control and dynamic operation of the Dual Active Bridge (DAB) DC-DC converter applied to high power charging of electric vehicle batteries. Starting with the presentation of the basic operation of the converter, followed by the two time-constant Thevenin-based battery modelling, an improved Fourier series-based generalized average model (GAM) of the converter is provided which considers the parasitic resistance of the output filter capacitor and is shown to have a massive effect on the dynamic operation of the converter. Furthermore, a novel combined feedforward plus feedback control system based on single phase-shift modulation is proposed for battery charging using the constant-current (CC)/constant-voltage (CV) cascaded loop strategy. The numerical results obtained from MATLAB/Simulink demonstrate the potency of the proposed control strategy and when compared to the traditional feedback-only control approach, the proposed approach shows a fast and seamless transition from the CC charging mode to the CV charging mode with very little undershoots, hence drastically improving the dynamic performance of the system with minimal controller effort, even in the presence of input voltage disturbances.