Symmetrical nine-phase drives with a single neutral-point: common-mode voltage analysis and reduction

Sherif M. Dabour*, Ahmed A. Aboushady, Mohamed A. Elgenedy, I. A. Gowaid, Mohamed Emad Farrag, Ayman S. Abdel-Khalik, Ahmed M. Massoud*, Shehab Ahmed

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
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Power converters generate switching common mode voltage (CMV) through the pulse width modulation (PWM). Several problems occur in the drive systems due to the generated CMV. These problems can be dangerous to the insulation and bearings of the electric machine windings. In recent years, many modulation methods have been developed to reduce the CMV in multiphase machines. Symmetrical nine-phase machines with single-neutral are considered in this paper. In this case, conventional PWM uses eight active vectors of different magnitudes in combination with two zero states in a switching cycle, and this generates maximum CMV. This paper proposes two PWM schemes to reduce the CMV in such a system. The first scheme is called active zero state (AZS). It replaces the zero vectors with suitable opposite active vectors. The second scheme uses ten large active vectors during switching and is called SVM-10L. Compared with conventional strategies, the AZS reduces the peak CMV by 22.2%, and the SVM-10L reduces the peak CMV by 88.8%. Moreover, this paper presents a carrier-based implementation of the proposed schemes to simplify the implementation. The proposed schemes are assessed using simulations and experimental studies for an induction motor load under different case studies.
Original languageEnglish
Article number12553
Number of pages17
JournalApplied Sciences
Issue number24
Early online date7 Dec 2022
Publication statusPublished - Dec 2022


  • nine-phase motor
  • space vector modulation (SVM)
  • common mode voltage (CMV)
  • nine-phase inverter


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