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 Geradab

Research output: Journal PublicationArticlepeer-review


Implementation of proportional-integral (PI) controllers in 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, rS2F, 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 discrete time domain is developed. This motivates the investigation of eliminating cross-coupling effects in PMSM drive systems. A new current control structure in the discrete time domain is proposed targeting full compensation of cross-coupling effects of SRF whilst 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)1
Number of pages1
JournalIEEE Journal of Emerging and Selected Topics in Power Electronics
Publication statusPublished - 30 May 2022


  • Control systems
  • Current control
  • DDPI
  • Delays
  • Low S2F tuning method
  • Power electronics
  • Regulators
  • Stators
  • Time-domain analysis
  • decoupled current control
  • decoupling
  • discrete-time system modeling

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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