Full-Speed Range Encoderless Control for Salient-Pole PMSM with a Novel Full-Order SMO

Abstract

For salient-pole permanent magnet synchronous motor (PMSM), the amplitude of extended back electromotive force (EEMF) is determined by rotor speed, stator current and its derivative value. Theoretically, even at extremely low speed, the back EEMF can be detected if the current in q-axis is changing. However, it is difficult to detect the EEMF precisely due to the current at low speed. In this paper, novel full-order multi-input and multi-output discrete-time sliding mode observer (SMO) is built to detect the rotor position. With the proposed rotor position estimation technique, the motor can start up from standstill and reverse between positive and negative directions without a position sensor. The proposed method was evaluated by experiment.

Keywords

• sliding mode observer (SMO)
• permanent magnet synchronous motor (PMSM)
• extended back electromotive force (EEMF)
• position sensorless