An improved flux observer based on PLL frequency estimator for sensorless vector control of induction motors

• Published in: IEEE transactions on industrial electronics (1982) Vol. 53; no. 1; pp. 50 - 56
• Main Authors: Comanescu, M., Xu, L.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2006; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Cutoff frequency; Electric potential; Estimates; Flux; Frequency estimation; Frequency synchronization; Induction machine; Induction motors; Low pass filters; Machine vector control; Mathematical analysis; Phase estimation; phase locked loop (PLL); Phase locked loops; sensorless control; Stators; vector control; Vectors (mathematics); Voltage
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2005.862317

This paper presents an improved method of flux estimation for sensorless vector control of induction motors based on a phase locked loop (PLL) programmable low-pass filter (LPF) and a vector rotator. A PLL synchronized with the voltage vector is used for stator frequency estimation. The pure integration of the stator voltage equations is difficult to implement and LPFs with a fixed cutoff provide good estimates only in the relatively high frequency range-at low frequencies, the estimates fail in both magnitude and phase. The method proposed corrects the above problem for a wide range of speeds. Simulations and experimental results on a 0.25-hp three-phase induction machine verify the validity of the approach.