Stable Operation and Current Sharing Control among Parallel Single-Phase ‎Inverter Modules with Unequal Filter Impedances

Document Type : Research paper


Department of Electrical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran


Parallel connection of two or even more single-phase inverter modules is a successful solution to increase the reliability and the efficiency of an inverter at moderate power levels. Stable operation and proper current sharing among parallel inverter modules is a key issue, especially when they are connected to a common load through unequal output filter impedances. In this paper, a new formulation and consequently a proper current sharing control algorithm for parallel connected inverter modules with the possibility of unequal filter impedances is proposed. Also a dual-loop voltage control with the filter current as the inner loop feedback signal, considering the effect of digital control delay, is adopted. The controller parameters are designed according to a frequency domain analysis. Finally, theoretical achievements are confirmed by experimental test results on a test rig with two 250 W parallel connected single phase inverters.


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Volume 10, Issue 2
August 2022
Pages 134-142
  • Receive Date: 21 July 2021
  • Revise Date: 01 October 2021
  • Accept Date: 13 October 2021
  • First Publish Date: 20 October 2021