Sensorless Direct Torque Control for Electrically Excited Synchronous Motor Based on Injecting High-Frequency Ripple Current Into Rotor Winding

• Published in: IEEE transactions on energy conversion Vol. 30; no. 1; pp. 246 - 253
• Main Authors: Zhou, Yangzhong, Long, Shipeng
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Direct torque control (DTC); electrically excited synchronous motor (EESM); Electromagnetics; Excitation; Flux; Hafnium; Ripples; rotor high-frequency (HF) ripple current; Rotors; sensorless; Stator windings; Stators; Synchronous motors; Torque; Winding; Direct torque control (DTC); rotor high-frequency (HF) ripple current; sensorless; electrically excited synchronous motor (EESM)
• ISSN: 0885-8969; 1558-0059
• DOI: 10.1109/TEC.2014.2360991

A novel rotor position angle estimator is proposed to achieve zero and very low operation speed for sensorless direct torque-controlled electrically excited synchronous motor (EESM) drive. First, high-frequency ripple current is injected into rotor winding, and second, using closed-loop torque control, high-frequency component is injected into electromagnetic torque to produce high-frequency stator current only in d-axis direction. At last, the rotor position angle is estimated with phase-locked loop principle. The stator flux and electromagnetic torque are calculated with stator flux current model and estimated rotor position angle, and then a sensorless direct torque-controlled EESM drive is constructed with estimated flux and torque. The experimental results show that the proposed sensorless EESM drive system can operate at zero and very low speed.