EMI and ground leakage current reduction in single-phase grid-connected power converter

Mohammad Hassan Hedayati; Vinod John

EMI and ground leakage current reduction in single-phase grid-connected power converter

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Author(s): Mohammad Hassan Hedayati ¹ and Vinod John ²
- Affiliations: 1: The School of Engineering, University of Aberdeen, Aberdeen, UK ;
  2: Department of Electrical Engineering, Indian Institute of Science (IISc), Bangalore 560012, India
Source: Volume 10, Issue 8, 30 June 2017, p. 938 – 944
DOI: 10.1049/iet-pel.2016.0568 , Print ISSN 1755-4535, Online ISSN 1755-4543

Received 20/08/2016, Accepted 05/03/2017, Revised 26/01/2017, Published 06/03/2017

Ground leakage current in a power converter is a major concern, which has stringent limitations due to safety concerns. Presence of high-frequency pulses, with high dv/dt due to switching actions in common-mode (CM) voltage, result in injection of current waveforms with large di/dt spikes into the ground and causes high electromagnetic interference (EMI) noise level. In this study, a new method is proposed to make the CM voltage, of a single-phase grid-connected inverter, sinusoidal and free of high-frequency pulses. The proposed method consists of two parallel connected H-bridge power converters, which uses unipolar pulse width modulation (PWM) with carrier interleaving angle of 180°. The proposed method reduces the ground leakage current by more than an order of magnitude. A novel modification to the LCL filter is proposed which further reduces the leakage current by 48%. It is shown that these modifications make the overall system insensitive to circuit non-idealities. Experimental results based on ground leakage current measurements on a 7.5 kW parallel single-phase PWM rectifier are presented. These results validate the effectiveness of the proposed method.

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EMI and ground leakage current reduction in single-phase grid-connected power converter

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