Digital notch filter based active damping for LCL filters

Wenli Yao, Yongheng Yang, Xiaobin Zhang, Frede Blaabjerg

Research output: Contribution to book/anthology/report/conference proceedingArticle in proceedingResearchpeer-review

24 Citations (Scopus)
834 Downloads (Pure)

Abstract

LCL filters are widely used in Pulse Width Modulation (PWM) inverters. However, it also introduces a pair of unstable resonant poles that may challenge the controller stability. The passive damping is a convenient possibility to tackle the resonance problem at the cost of system overall efficiency. In contrast, the active damping does not require any dissipation elements, and thus has become of increasing interest. As a result, a vast of active damping solutions have been reported, among which multi-loop control systems and additional sensors are necessary, leading to increased cost and complexity. In this paper, a notch filter based active damping without the requirement of additional sensors is proposed, where the inverter current is employed as the feedback variable. Firstly, a design method of the notch filter for active damping is presented. The entire system stability has then been investigated, which has revealed that negative variations of the resonant frequency can seriously affect the system stability. In order to make the controller more robust against grid impedance variations, the notch filter frequency is thus designed smaller than the LCL filter resonant frequency, which is done in the z-domain. Simulations and experiments are carried out to verify the proposed active damping method. Both results have confirmed that the notch filter based active damping can ensure the entire system stability in the case of resonances with a good system performance.
Original languageEnglish
Title of host publicationProceedings of the 2015 IEEE Applied Power Electronics Conference and Exposition (APEC)
Number of pages8
PublisherIEEE Press
Publication dateMar 2015
Pages2399-2406
ISBN (Print)978-1-4799-6735-3
DOIs
Publication statusPublished - Mar 2015
Event30th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2015 - Charlotte, United States
Duration: 15 Mar 201519 Mar 2015

Conference

Conference30th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2015
CountryUnited States
CityCharlotte
Period15/03/201519/03/2015
SeriesI E E E Applied Power Electronics Conference and Exposition. Conference Proceedings
ISSN1048-2334

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