Design of a Disturbance Observer-based Controller for DC/DC Boost Converter

S.-J. Kim (Korea), Y.I. Son (Korea, USA), H. Shim, and Y.-S. Jeong (Korea)

Keywords

DC/DC Boost Converter, Load Variation, Disturbance Observer (DOB), Nonminimum Phase system, Parallel Interconnection

Abstract

Output voltage of a DC/DC power converter system is likely to be distorted if variable loads exist in the output terminal. This paper proposes a disturbance observer based controller for a boost type DC/DC converter system to maintain a robust performance against load variations. The regulation problem of the boost converter is very complicated by the fact that, with respect to the output voltage to be regulated, the system is non-minimum phase. Since the DOB structure has the inverse of nominal transfer function of plants, most DOB approaches have been limited to minimum phase systems (or systems having no zero dynamics). We consider a new DOB structure that enables application of the original DOB approach even to non minimum phase system. The proposed DOB structure is a simple modification of the original DOB by adding a new filter in parallel with the plant. The filter, which is called as V-filter, is designed so that the parallel connection with the plant becomes of minimum phase. For the disturbance rejection performance of the proposed control algorithm, we discuss a gain condition of the V-filter in low frequency range. It is shown that if a given non-minimum system can be stabilized by a PID controller, we can easily construct the additional filter by inverting the controller's transfer function.

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