Abstract: The classical model prediction algorithm of three-level grid-connected converter has many

disadvantages，such as large computation，unfixed switching frequency and difficulty in selecting weight factors，

which limit its development in grid-connected converter field. To solve above problems，a modified control algorithm based on the optimal vector synthesis prediction was presented. Through selecting the seven real switch vectors in each control cycle，then，selecting three optimum switch vectors based on the minimum of the cost function，the switch conduction time was calculated directly by the cost function of the selected voltage vector. Finally，the reliability of the strategy was verified by the complete simulation and test analysis.

      Key words: three-level grid-connected converter；model predictive；space voltage vector modulation；optimal

vector