Decoupled Discrete Current Control for AC Drives at Low Sampling-to-Fundamental Frequency Ratios

Meiqi Wang, Giampaolo Buticchi, Jing Li, Chunyang Gu, David Gerada, Michele Degano, Lie Xu, Yongdong Li, He Zhang, Chris Gerada

Research output: Journal PublicationArticlepeer-review

3 Citations (Scopus)


Implementation of proportional-integral (PI) controllers in the synchronous reference frame (SRF) is a well-established current control solution for electric drives. It is a general and effective method in digital control as long as the ratio of sampling-to-fundamental (S2F) frequency ratio, r_{mathrm {S2F}} , remains sufficiently large. When the aforesaid condition is violated, such as operations in high-speed or high-power drives, the performance of the closed-loop system becomes incrementally poor or even unstable. This is due to the cross-coupling of the signal flow between d - and q -axes, which is introduced by the SRF. In this article, an accurate model of current dynamics, which captures the computational delay and PWM characteristics in the discrete-time domain, is developed. This motivates the investigation of eliminating cross-coupling effects in permanent magnet synchronous motor (PMSM) drive systems. A new current control structure in the discrete-time domain is proposed targeting full compensation of cross-coupling effects of SRF while improving dynamic stiffness at low S2F ratios. The matching simulation and experimental results carried out on a 5-kW high-speed drive corroborate the theoretical analysis.

Original languageEnglish
Pages (from-to)1358-1369
Number of pages12
JournalIEEE Journal of Emerging and Selected Topics in Power Electronics
Issue number2
Publication statusPublished - 30 May 2022


  • Decoupled current control
  • decoupled discrete proportional - integral (DDPI)
  • decoupling
  • discrete-time system modeling
  • low sampling-to-fundamental (S2F) tuning method

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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