Internal Current Return Path for Ground Leakage Current Mitigation in Current Source Inverters

Emilio Lorenzani, Giovanni Migliazza, Fabio Immovilli, Chris Gerada, He Zhang, Giampaolo Buticchi

Research output: Journal PublicationReview articlepeer-review

15 Citations (Scopus)
77 Downloads (Pure)


This paper analyzes in detail the effect of a simple solution for ground leakage current mitigation applicable to transformerless three-phase current source inverter (CSI). The circuit modification solution is assessed for both traditional CSI topology and for CSI with an additional seventh switch, in literature named CSI7 (or H7), in particular with the splitting of the dc input inductance. In the present work, the solution is applied to grid-connected converters for string photovoltaic applications: scope of the circuit modification is to provide an internal return path from the wye connected capacitors of the output CL filter. This additional return path is able to significantly reduce the ground leakage current without adversely affecting THD. The performance of the proposed solution is assessed by the numerical simulations in case of a string of photovoltaic (PV) modules and the different behavior of CSI and CSI7 topologies is thoroughly investigated. Furthermore, the definition of V-{cmZC} is assessed by applying it to the common mode equivalent circuits for CSI7 with additional return path and their validation by means of a two-step simulation. The simulation results and experimental validation shows good agreement and confirm that the proposed solution is able to strongly reduce the ground leakage current.

Original languageEnglish
Article number8764348
Pages (from-to)96540-96548
Number of pages9
JournalIEEE Access
Publication statusPublished - 2019


  • Current source inverter
  • ground leakage current
  • photo-voltaic power systems
  • renewable energy sources

ASJC Scopus subject areas

  • General Computer Science
  • General Materials Science
  • General Engineering


Dive into the research topics of 'Internal Current Return Path for Ground Leakage Current Mitigation in Current Source Inverters'. Together they form a unique fingerprint.

Cite this