Abstract: Model predictive control (MPC) has been widely used in grid-connected converter control systems with the advantages, such as easy implantation and multi-target tracking. However, the unfixed switching state of the traditional model predictive control algorithm will reduce the accuracy of current tracking and even produce large current ripple. Therefore, a double closed loop control method based on model predictive direct power fixed frequency control (DPCMPC) and sliding mode control (SMC) is proposed. The SMC outer ring is used to obtain a given value of the active power of the system, and the steady-state performance of the system is improved by introducing a zero voltage vector and the power ripple is reduced. In order to verify the theoretical analysis, a complete simulation and experimental test model was constructed, and the results show that the proposed control method has good steady-state and dynamic performance.

Key words: T-type grid-connected converter, finite set model predictive, sliding mode control, direct power control, fixed frequency control