LAUSR

The harmonic interaction analysis of delta-connected cascaded H-bridge (CHB) multilevel converter as shunt active power filter (APF) is helpful for design and control purposes. This paper presents a harmonic interaction analysis based on the derivation of a current and energy-based time-invariant state-space model with switching functions unknown beforehand. Based on that, we are capable to predict the harmonics propagation through the system and provide a precise calculation of various electrical quantities and switching functions that contain multiple frequency components with possible imbalances, giving an accurate reference for understanding, designing, and controlling of delta-connected CHB. The validity and accuracy of the harmonic interaction analysis are verified by the simulations of delta-connected CHB-based APF equipped with dc-link capacitors of reduced values.