Park Vector Based Sliding Mode Control of UPS With Unbalanced and Nonlinear Load

Abstract

In this paper an inverter is taken as a member of Variable Structure System (VSS). A new Park vector based variable structure control (VSC) method is proposed. A modified definition of the Park vector is introduced to handle the effect of zero phase-sequence component caused by an asymmetrical load. The design of a sliding mode controller consists of two main steps. Firstly, the design of the sliding surface, secondly, the design of the control which holds the system trajectory on the sliding surface. A complex sliding surface is proposed. The inverter is switched in such a way that the system trajectory gets as close to the sliding surface as possible. This paper focuses on the switching rule. Experimental results of a 100 KVA inverter are presented.