Analysis and modelling of circulating current in two parallel-connected inverters

Ramkrishan Maheshwari*, Ghanshyamsinh Gohil, Lorand Bede, Stig Munk-Nielsen

*Corresponding author for this work

Research output: Contribution to journalJournal article


Parallel-connected inverters are gaining attention for high power applications because of the limited power handling capability of the power modules. Moreover, the parallel-connected inverters may have low total harmonic distortion of the ac current if they are operated with the interleaved pulse-width modulation (PWM). However, the interleaved PWM causes a circulating current between the inverters, which in turn causes additional losses. A model describing the dynamics of the circulating current is presented in this study which shows that the circulating current depends on the common-mode voltage. Using this model, the circulating current between two parallel-connected inverters is analysed in this study. The peak and root mean square (rms) values of the normalised circulating current are calculated for different PWM methods, which makes this analysis a valuable tool to design a filter for the circulating current. The peak and rms values of the circulating current are plotted for different PWM methods, and a discontinuous PWM is identified which offers the minimum peak and rms value of the circulating current. Experimental results are presented to verify the analysis.

Original languageEnglish
JournalIET Power Electronics
Issue number7
Pages (from-to)1273-1283
Number of pages11
Publication statusPublished - 1. Jul 2015

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