A Multi-Step Model Predictive Direct Thrust Control Method for Linear Synchronous Motors Driven by Three-Level NPC Inverters

The standard direct thrust control (DTC) method is not suitable for multi-level inverters and is difficult to deal with complex constraints. In this article, a new prediction model is proposed. It has low computational complexity. Based on this prediction model, a new multi-step model predictive direct thrust control (MP-DTC) method for high-power linear synchronous motors (LSM) is designed. In order to reduce the switching frequency and control the neutral point voltage of three-level neutral-point-clamped (NPC) inverters, new constraint conditions and value functions are designed. Compared to the traditional MP-DTC, the proposed two-step MP-DTC strategy proposed in this article can reduce the switching frequency by 43%. In addition, this method can effectively suppress the neutral point voltage unbalance of three-level NPC inverters in a convenient way. The mean absolute deviation is 1.88%.