Nonlinear Optimal DTC Design and Stability Analysis for Interior Permanent Magnet Synchronous Motor Drives

Ton Duc Do, Han Ho Choi, Jin Woo Jung

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


This paper presents a nonlinear optimal direct torque control (DTC) scheme of interior permanent magnet synchronous motors (IPMSMs) based on an offline approximation approach for electric vehicle (EV) applications. First, the DTC problem is reformulated in the stationary reference frame in order to avoid estimating the stator flux angle, which the previous DTC schemes in the rotating stator reference frame require. Thus, the proposed DTC method eliminates the Park's transformation, and consequently, it reduces the computational efforts. Particularly, since the estimated stator flux angle is not accurate in low speed range, the proposed method that does not need this information can significantly improve the control performance. Moreover, a nonlinear optimal DTC algorithm is proposed to deal with the nonlinearity of the IPMSM drive system. In this paper, a simple offline θ-D approximation technique is utilized to appropriately determine the controller gains. Via an IPMSM test bed with a TI TMS320F28335 DSP, the experimental results demonstrate the feasibility of the proposed DTC method by accomplishing better control performances (e.g., more stable in low speed region, much smaller speed and torque ripples, and faster dynamic responses) compared to the conventional proportional-integral DTC scheme under various scenarios with the existence of parameter uncertainties.

Original languageEnglish
Article number7095581
Pages (from-to)2716-2725
Number of pages10
JournalIEEE/ASME Transactions on Mechatronics
Issue number6
Publication statusPublished - Dec 2015


  • Direct torque control (DTC)
  • electric vehicle (EV)
  • interior permanent magnet synchronous motor (IPMSM)
  • nonlinear optimal control

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Computer Science Applications
  • Electrical and Electronic Engineering

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