Model Predictive Direct Power Control Based on Improved T-Type Grid-Connected Inverter

In this paper, the improved T-type three-level topology can significantly reduce the conduction loss in zero states compared with the traditional T-type three-level topology. In the direct-axis and quadrature-axis rotating coordinate system, a control method combining the model predictive algorithm and the direct power control (DPC) is proposed. This control method divides 27 kinds of switch states into two groups and decides which group of switch states is to be scrolled optimally by comparing the two capacitor voltages on the dc side. This method reduces the computational burden by reducing the number of rolling optimization under the condition of ensuring the neutral point voltage balance. Compared with the traditional multilevel model predictive control, the method eliminates the need for predicting the neutral-point voltage as well as the cost function computation, and the control method is more direct and effective. Simulation and experimental results show that the proposed model predictive DPC method based on the improved T-topology can improve system robustness, fast dynamic response, wide operating range, and stability.