Improved Control Method for Reducing Decoupling Cell Size in Four-Switch Three-Port Converters

This letter deals with a single-phase, nonisolated on-board charger (OBC) for electric vehicles (EVs) based on a four-switch three-port (FSTP) converter topology with a power decoupling function. However, in the published literature, the size of the decoupling cell (inductor and capacitor) is generally large, making promotion and application challenging. To minimize the decoupling cell size, an improved power decoupling control method is proposed in this letter. Specifically, the decoupling cell inductor current reference value is generated by using the output of a proportional integral (PI) plus proportional-resonant (PR) controller so that the decoupling cell can absorb double-line frequency power to the maximum extent. The proposed control method is implemented in a 500Wlaboratory prototype. Compared with the existing control method, under the same operating condition, the proposed approach reduces the output direct current (dc) voltage ripple by 71.2%, the decoupling capacitance by 40%, and the decoupling inductance by 66.6%.