The low-frequency current ripple that always appears at the input of the single-phase DC/AC inverters decreases the
lifetime of DC voltage sources, such as fuel cells and chemical batteries. In this study, based on series and parallel feedback
theory, a proportional-integral (PI) controller is designed for the front-end boost converter in two-stage power converters. This
controller increases the output impedance of the boost converter, which reduces the low-frequency current ripple at the input
of this two-stage converter. Since the designed controller corrupts the dynamic response of the boost converter, the DC-link
voltage severely over/undershoots in step load conditions. Overcoming this issue by employing a non-linear gain in the
forward path is shown. By applying this proposed technique, the output voltage over/undershoot stays in an acceptable range.
Therefore both the low-frequency input current ripple and the DC-link over/undershoot problems disappear simultaneously
without employing any additional equipment, especially a bulky DC capacitor. The simulation and experimental results for a
2.5 kW prototype confirm the performance of the proposed idea.