Improved model predictive current control for multi-mode four-switch buck-boost converter considering parameter mismatch

Four-switch Buck-Boost (FSBB) converter usually adopts multi-mode control methods in applications requiring both voltage step-up and step-down. Model predictive current control (MPCC) can improve the dynamic performance and simplify multi-mode switching control, but parameter mismatch will deteriorate its control performances. To this end, the theoretical steady-state error of MPCC caused by parameter mismatch is derived; the influence of parameter mismatch on the dynamic and steady-state performances is analyzed. Further, an improved MPCC strategy with the parameter disturbance observer (PDO) and dynamic adjustment block for the FSBB converter is presented. The PDO is developed to correct the prediction model and eliminate steady-state errors due to parameter mismatch. The dynamic adjustment block related to the tracking error can further avoid the dynamic performance degradation. Additionally, a load disturbance observer (LDO) is designed to improve the dynamic response to the unknown load variation. Then, multi-mode operation of the FSBB converter is realized with the proposed MPCC, which determines the operating mode according to the prediction results without extra mode detection. Finally, simulation and experimental results demonstrate that the proposed strategy can improve the dynamic and steady-state performances of MPCC with parameter mismatch and achieve multi-mode operation with high control performances.