Guidelines to Classical Frequency-Domain Disturbance Observer Redesign for Enhanced Rejection of Periodic Uncertainties and Disturbances

Moria Elkayam, Sergei Kolesnik, Alon Kuperman

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

The paper suggests a method aimed to improve the performance of dynamical systems with periodic uncertainties and disturbances (ac power converters are typical representatives of such systems) utilizing frequency-domain disturbance observer (DOB)-based control structure. In such control arrangement, DOB filter is the key component and should be designed so that its magnitude (phase) is as close to unity (zero) as possible at frequencies where the total uncertainty and disturbance exists. The methodology for designing DOB filters is well established mostly for systems with slow-varying uncertainties/disturbances and has been barely extended to systems with periodic excitation (such as grid-connected or stand-Alone ac power converters). In this study, systematic enhancement of DOB filters, designed according to the classical methodology, is suggested based on appropriate mixing with a series multiresonant term. The proposed approach allows attaining improved periodic signals rejection capability while significantly sacrificing neither the dc gain nor the crossover frequency. Quantitative design guidelines are provided, and possible tradeoffs are revealed. The proposed methodology is validated by application to current control of LCL-filter-based inverter connected to a distorted ac grid. Feasibility and performance of the suggested approach are well supported by simulations and experiments.

Original languageEnglish
Article number8437189
Pages (from-to)3986-3995
Number of pages10
JournalIEEE Transactions on Power Electronics
Volume34
Issue number4
DOIs
StatePublished - 1 Apr 2019

Keywords

  • Disturbance observer (DOB)
  • multiresonant term
  • periodic uncertainty and disturbance

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