In the cascaded H-bridge inverter (CHBI) with supercapacitor and dc-dc stage. inherent second-order harmonic power flows through each submodule (SM). causing fluctuations in both the dc-link voltage and the dc-dc current. There exist limitations in handling these fluctuations at variable output frequencies when employing proportional-integral (PI) control to the dc-dc stage. https://pipingrockers.shop/product-category/eye-drops/