A Fast Model Predictive Control with Fixed Switching Frequency Based on Virtual Space Vector for Three-Phase Inverters

This paper proposes an improved finite control set model predictive control (FCS-MPC) algorithm based on virtual space vector to reduce computational burden, and achieve a constant switching frequency for two-level three-phase inverters. The voltage vector reference is calculated in a 60 degrees coordinate system according to the principle of deadbeat (DB) technique. A large number of virtual voltage vectors synthesized by discrete space vector modulation (DSVM) is utilized to approach the voltage vector reference. To avoid enumerating all the virtual voltage vectors from a look-up table, an algebraic way using the voltage vector reference is adopted to calculate the three candidate vectors. Then, a cost function is defined to select the optimal voltage vector among them. This new method greatly improves the computation efficiency since plenty of multiply operation is eliminated in the 60 degrees coordinate system. Moreover, a fixed switching frequency is achieved since the durations of each switch states has been calculated. Experimental results under a two-level three-phase inverter verify the effectiveness of the proposed control strategy.