A Robust Multivariable Approach for Current Control of Voltage-Source Converters in Synchronous Frame

This article presents a new vector current controller for the grid-connected three-phase voltage-source converter (VSC). The VSC is increasingly used in many applications, such as distributed generation, motor drives, and high-voltage dc (HVdc) systems. From a control system perspective, this presents a two-input two-output coupled problem when transformed into the synchronous rotating reference frame. The common approach is to decouple the two control loops and use two single-input single-output (SISO) controllers. There are also some more recent approaches to treat the problem using multivariable or model predictive techniques. The proposed controller of this article is based on a multi-input multi-output (MIMO) approach that, compared with existing approaches, offers: 1) a significantly improved robust performance and 2) a convenient systematic and optimal design procedure. Details of the proposed approach and multiple simulation and experimental testings are presented to demonstrate the proposed controller.