Minimum phase bipolar converter for DC microgrid applications

Abstract

This study proposes a minimum phase bipolar converter for dc microgrid applications, which is derived from the combination of C'uk and Sepic converters with some modifications in both of them in order to get a minimum phase system. In the proposed bipolar converter (PBC), the equivalent series resistance of transfer capacitors of both C'uk and Sepic converters is increased by adding resistances and introducing magnetic coupling between the filter inductors of the Sepic converter with a series RC network. These circuit modifications eliminate right half plane zero from the PBC and thereby make it a minimum phase, unlike the conventional C'uk-Sepic bipolar converter. Due to the minimum phase behaviour, the proposed converter can deliver high load current, achieves high bandwidth and facilitates simpler controller design in contrast to the conventional C'uk- Sepic bipolar converter. Detailed steady state and dynamic modelling of the PBC has been carried out in order to show its advantages. A 500 W laboratory prototype has been developed and implemented using field programmable gate array-based system to verify the operation of the proposed converter. © The Institution of Engineering and Technology 2019.