Constrained optimal control of the step-down dc-dc converter

Tobias Geyer, Georgios Papafotiou, Roberto Frasca, Manfred Morari

Research output: Contribution to journalArticleAcademicpeer-review

120 Citations (Scopus)

Abstract

In this paper, we propose a novel approach to the modeling and controller design of the synchronous step-down dc-dc converter. We introduce a hybrid converter model that is valid for the whole operating regime and captures the different modes of operation. Based on this model, we formulate and solve a constrained optimal control problem. This allows a systematic controller design that achieves the regulation of the output voltage to its reference despite input voltage and output load variations while satisfying the constraints on the duty cycle and the inductor current. The resulting state-feedback control law is of piecewise affine form, which can be easily stored and implemented in a lookup table. A Kalman filter is added to account for unmeasured load variations and to achieve zero steady-state output voltage error. Experimental results demonstrate the potential advantages of the proposed control methodology.

Original languageEnglish
Article number4689456
Pages (from-to)2454-2464
Number of pages11
JournalIEEE Transactions on Power Electronics
Volume23
Issue number5
DOIs
Publication statusPublished - 2008
Externally publishedYes

Funding

Manuscript received September 04, 2007; revised January 04, 2008. Current version published December 02, 2008. This work was supported by the two European Commission research projects IST-2001-33520 Control and Computation (CC) and FP6-IST-511368 Hybrid Control (HYCON). Part of this work was previously presented at the 2004 IEEE Workshop on Computers in Power Electronics (COMPEL), Champaign, IL, August 2004. This work was done at the Automatic Control Laboratory, ETH Zurich, Switzerland. Recommended for publication by Associate Editor J. Pomilio.

Keywords

  • Dc-dc converter
  • Hybrid system
  • Model predictive control (MPC)
  • Optimal control
  • Piecewise-affine (PWA) system
  • Power electronics

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