Model Predictive Control Method for Nonisolated Universal Battery Charger

This paper proposes a Model Predictive Control (MPC) method for a universal bridgeless non-isolated wide-output voltage range onboard battery charger. The onboard battery charger has two different (boost and buck) operation modes in one cycle of the grid voltage. While the boost mode occurs twice in each half cycle, the buck mode takes place once in every half cycle. Contrary to the existing control methods, the proposed MPC method is based on grid current control and does not need a mode detection algorithm. Aside from this feature, the proposed method offers easy implementation, fast dynamic response, and no need for complex modulation schemes. The grid current reference is generated by a proportional-integral (PI) controller depending on the battery's current or voltage, since the battery should be charged in constant current (CC) and constant voltage (CV) modes. Simulation studies are conducted to investigate the effectiveness of the proposed control strategy for non-isolated wide-output voltage range bridgeless onboard battery chargers. Simulation studies are conducted using two different battery models having nominal voltages of 48V and 350V. The results reveal that the proposed method successfully charges the two batteries in both CV and CC modes. Moreover, the grid current is maintained at unity power factor and total harmonic distortion (THD) is smaller than the limits defined in international standards.