T31.4 - Optimal L-Filter Design Method Considering Impact of Control Frequency for Single-Phase Grid-Connected H-Bridge Inverters

When the control frequency is lower than the switching frequency, an additional ripple component in the control frequency band appears in the phase current, and its influence becomes more pronounced as the control frequency decreases. Although this component accounts for a nonnegligible portion of the total ripple components, existing L-filter design methods previously presented do not consider it, leading to selecting an inductance value that does not meet the desired phase current total harmonic distortion (THD). This can potentially result in failure to satisfy the design requirements or an overdesign if the component is considered by only adding a rough design margin, which degrades power density. In this paper, an optimal L-filter design method for single-phase grid-connected H-bridge inverters is proposed, which considers the impact of control frequency. The ripple components in the phase current due to each factor are precisely analyzed, and derived to determine the optimized filter inductance satisfying the target current THD. The effectiveness of the proposed method is verified through simulation results.