Robust Dynamic Control of Constant-Current-Source-Based Dual-Active-Bridge DC/DC Converter Used for Off-Board EV Charging

Abstract

Due to the high power density, inherent zero-voltage-switching (ZVS), and high voltage-conversation ratio, the current source-based isolated dual-active-bridge DAB–DC/DC converters are extensively used for charging EVs under constant-current mode. However, the fast dynamic response of an output current is a crucial requirement for dual-active-bridge DC/DC converters operating as a constant-current source. This study proposes a fast current controller (FCC) for tracking the desired output current under various input/output parameter disturbances/variations. The proposed control strategy can ensure a fast transient response with negligible overshoot/undershoot for output current during start-up and when there are variations in the load or input voltage. Furthermore, the dynamic behavior of the current control against change in the reference current value has also been improved. A constant-current-based DAB–DC/DC converter is modeled and simulated in MATLAB/Simulink software and a scaled-down 300 W lab prototype DAB–DC/DC converter is designed with the TMS320F28335 DSP controller of Texas Instruments. To verify the effectiveness of the proposed current controller, different test cases, such as a change in the load, a change in the input voltage, and a change in the desired output current, are considered. Moreover, under these test cases, the proposed current-control strategy is compared with the conventional proportional–integral (PI) current controller, model-based phase-shift controller (MBPS), and load current feed-forward controller (LCFF). Both the experimental and simulation results have validated the effectiveness of the proposed control strategy.

Keywords

• renewable energy
• bidirectional DAB–DC/DC converter
• constant-current control
• fast dynamic performance
• off-board EV charging