Effect of Multilevel Inverter Supply on Core Losses in Magnetic Materials and Electrical Machines

Paavo Rasilo, Aboubakr Salem, Ahmed Abdallh, Frederik De Belie, Luc Dupré, Jan A. Melkebeek

Research output: Contribution to journalArticleScientificpeer-review

27 Citations (Scopus)


The effect of multilevel inverter supply on power losses in magnetic cores and electrical machines is studied. A dynamic numerical model for the hysteresis, eddy current, and excess losses in a core lamination is first developed. By both measurements and simulations for a ring-core inductor, we demonstrate how increasing the number of inverter voltage levels decreases the iron losses when compared with traditional two-level supply. Although the switching frequency has a significant impact on the iron losses in the case of a traditional two-level inverter, using three or five voltage levels makes the losses almost independent of the switching. Finally, finite-element simulations show that similar reductions are also possible for the core losses of 150-kVA and 12.5-MW wound-field synchronous machines, in which rather low switching frequencies are typically used. Calorimetric loss measurements are also presented for the 150-kVA machine in order to confirm the significant effect of switching frequency on the core losses with two-level inverter supply.

Original languageEnglish
Article number6980114
Pages (from-to)736-744
Number of pages9
JournalIEEE Transactions on Energy Conversion
Issue number2
Publication statusPublished - 1 Jun 2015
MoE publication typeA1 Journal article-refereed


  • Eddy currents
  • electrical machines
  • excess loss
  • finite-element analysis
  • iron loss
  • magnetic hysteresis
  • magnetic materials
  • multilevel converter
  • pulse width modulation


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