Model predictive current control with optimal duty cycle for three-phase grid-connected AC/DC converters

Conventional model predictive current control (M-PCC) uses the discrete-time system model to select the best voltage vector by minimizing a cost function, which is related to the current errors. However, due to the limited number of voltage vectors in two-level converters, the sampling frequency has to be high to achieve satisfactory performance. To improve the steady state performance of conventional single-vector-based MPCC, this paper proposes an improved MPCC with optimal duty cycle for a three-phase ac/dc converter. The proposed method allocates only a fraction of control period to the voltage vector selected from conventional MPCC and the rest of time for a zero vector. The duration of the selected voltage vector is obtained based on the principle of current error minimization. Both simulation and experimental results validate the effectiveness of the proposed method.