Time-Step-Adaptive Filter Discretization for Variable Sampling Frequency Control of Power Converters

This article proposes a time-step-adaptive filter discretization method for variable sampling frequency (VSF) control considering the effect of the previous sampling time steps on the filter response. The proposed discretization method is upon discretized integral equation in conjunction with prewarping to ensure accurate filter responses. The frequency responses shown in the bode plots of the digital filters and the experimental results of the single-phase totem-pole ac–dc converter control demonstrates the superiority of the proposed method compared to the conventional discretization method with one-to-one mapping. The proposed discretization principle has a promising potential for digital control of power converters and electric machines under VSF.