Optimal Sampling Frequency of SVPWM for Multilevel Converter

Abstract

With the increasing application of space vector pulse width modulation (SVPWM) strategy in multilevel converters, the sampling frequency selection of SVPWM algorithm becomes a new problem. This paper proposes a method to calculate the optimal sampling frequency of SVPWM. First, the vector space of the n-cell CHBMC is divided into 4n + 1 layers. According to the intersections between the reference vector trajectory and different layers, the number of sector triangles traversed by the reference vector trajectory in adjacent layers is calculated. Then, the number of sector triangles traversed by the reference vector trajectory in the range of 0 – 30° is calculated. Finally, according to the symmetry principle, the number Nt of sector triangles traversed by the reference vector trajectory in one reference signal period is calculated. The optimal sampling frequency is the product of Nt and the frequency of the reference signal. Simulation results prove the correctness and feasibility of the optimal sampling frequency proposed in this paper.