A Novel Adaptive Observer-Based DC-Link Voltage Control for Grid-Connected Power Converters

In the past decades, renewable energy has been experiencing significant growth due to the increasing energy demand and critical environmental issues. In order to perform power conversion and grid integration for these distributed energy resources, grid-connected power converters are therefore widely used. In a typical three-phase grid-connected power converter, DC-link capacitors are normally used as an energy buffer to maintain a proper DC voltage for the power conversion. However, the DC-link voltage varies significantly when the input power from the distributed energy resources changes rapidly. Hence, a proper DC-link voltage controller is essential to perform fast DC-link voltage regulation. In this paper, a novel adaptive observer-based DC-link voltage control is proposed for three-phase grid-connected power converters to minimize the DC-link voltage fluctuation and to improve the stability of the state observer.