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Mitigation of DC Current Injection in Transformer-less Grid-connected Inverters Using a Voltage Filtering DC extraction Approach

Lookup NU author(s): Weichi ZhangORCiD, Dr Matthew Armstrong, Dr Mohammed Elgendy



This is the authors' accepted manuscript of an article that has been published in its final definitive form by IEEE, 2019.

For re-use rights please refer to the publisher's terms and conditions.


IEEE Transformerless grid connected PV inverters are an attractive technology choice due to their high efficiency performance and relatively small volume. However, in the absence of galvanic isolation, dc current can potentially flow into the grid and adversely affect the grid performance. In addition, as the sinusoidal ac output is significantly larger than the dc injection component, accurate dc current sensing at the inverter output remains a technical challenge. As a result, this paper proposes a two-stage dc voltage detection technique that employs an isolated RC attenuation circuit and a software dc-component filtering algorithm. This cost-effective combination facilitates accurate dc component extraction which can be used as digital dc feedback for active current control purposes. Experimental results from a laboratory prototype demonstrate the high performance of the proposed dc extraction and suppression approach.

Publication metadata

Author(s): Zhang W, Armstrong M, Elgendy MA

Publication type: Article

Publication status: Published

Journal: IEEE Transactions on Energy Conversion

Year: 2019

Volume: 34

Issue: 1

Pages: 426-434

Print publication date: 01/03/2019

Online publication date: 04/10/2018

Acceptance date: 24/09/2018

Date deposited: 24/10/2018

ISSN (print): 0885-8969

ISSN (electronic): 1558-0059

Publisher: IEEE


DOI: 10.1109/TEC.2018.2874101


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