Direct current ripple compensation for multi-phase fault-tolerant machines

A.A. Abd Hafez, R. Todd, A.J. Forsyth, Andrew M. Cross

Research output: Contribution to journalArticlepeer-review


A second-harmonic direct current (DC) ripple compensation technique is presented for a multi-phase, fault-tolerant, permanent magnet machine. The analysis has been undertaken in a general manner for any pair of phases in operation with the remaining phases inactive. The compensation technique determines the required alternating currents in the machine to eliminate the second-harmonic DC-link current, while at the same time minimising the total rms current in the windings. An additional benefit of the compensation technique is a reduction in the magnitude of the electromagnetic torque ripple. Practical results are included from a 70 kW, five-phase generator system to validate the analysis and illustrate the performance of the compensation technique.
Original languageEnglish
Pages (from-to)28-36
Number of pages9
JournalIET Electric Power Applications
Issue number1
Publication statusPublished - Jan 2011


  • direct current ripple compensation
  • electromagnetic torque ripple
  • multiphase fault tolerant machines
  • permanent magnet machine
  • power 70 kW
  • second-harmonic DC-link current


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