Dual-Mode Bidirectional LLC-DAB Converter Based on a Modulated Coupled Inductor

The LLC resonant converter and dual-active-bridge (DAB) converter are attractive topologies to be used in bidirectional power applications for their respective advantages. In this letter, a dual-mode bidirectional LLC-DAB converter based on a modulated coupled inductor is proposed to combine the LLC and DAB converter into a single converter. By only modulating the PWM signals, the LC tank of the converter in two operation modes can be changed without adding any other additional diodes or switches. Meanwhile, by utilizing the modulated coupled inductor, the inductance of the LC tank will be different for two operation modes. The small leakage inductance is suitable for resonance with resonant capacitor in the LLC mode. And the large inductance is adopted to transfer the power in the DAB mode. Therefore, the LC tank parameters for two operation modes can be designed separately. The principle of the proposed dual-mode converter based on the modulated coupled inductor is investigated. After that, the parameters design consideration of the converter is given. Finally, a 2000-W prototype is built to verify the effectiveness of the proposed converter.