Suboptimal control scheme design for interior permanent-magnet synchronous motors: An SDRE-based approach

Ton Duc Do, Sangshin Kwak, Han Ho Choi, Jin Woo Jung

Research output: Contribution to journalArticlepeer-review

67 Citations (Scopus)


This paper designs a suboptimal speed controller as well as a suboptimal load torque observer based on state-dependent Riccati equation (SDRE) approach for interior permanent-magnet synchronous motor (IPMSM) servo systems. First, dynamic equations of the IPMSMs are transformed to a suitable form that makes an SDRE-based control technique applicable. Moreover, the maximum torque per ampere (MTPA) control is incorporated to improve the torque generation in the constant torque region. The asymptotic stabilities of the proposed controller and load torque observer are fully guaranteed through an extended linear quadratic regulator (LQR) theory. This proposed method is simple to implement because the SDRE solutions are approximated off-line. The proposed observer-based suboptimal control scheme can ensure faster dynamic response, smaller steady-state error, and more robust response than the LQR and proportional-integral (PI) controller under the system parameter variations and load torque disturbances. The effectiveness of the proposed control strategy is verified via experiment.

Original languageEnglish
Article number6556952
Pages (from-to)3020-3031
Number of pages12
JournalIEEE Transactions on Power Electronics
Issue number6
Publication statusPublished - Jun 1 2014
Externally publishedYes


  • Interior permanent-magnet synchronous motor (IPMSM)
  • Taylor series method
  • maximum torque per ampere (MTPA)
  • nonlinear control
  • nonlinear observer
  • state-dependent Riccati equation (SDRE)
  • suboptimal control

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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