Model Predictive Control for Six-Step Operation of PMSM Based on Adapted Fast Gradient Method

This article proposes model predictive control (MPC) of permanent magnet synchronous machines covering both the space vector modulation and the six-step operation. According to the estimated stator flux and its reference trajectory corresponding to modulation methods, the optimization problem is formulated and solved through the adapted fast gradient method (FGM). The proposed FGM performs the projection operation through the offset voltage injection method and calculates gradients by dynamic programming to reduce the computational cost. Based on the proposed FGM, the MPC is devised with the system state compensation under the six-step operation. The validity of the proposed work is verified by simulation and experiments. By the proposed MPC, the flux regulation reveals optimized dynamic performance under the seamless transition between the space vector modulation and the six-step operation. Moreover, the computation time of the gradient calculation and projection operation are, respectively, reduced by 52% and 9.1%, compared to the conventional method.