A Novel Flux Estimator Based on Multiple Second-Order Generalized Integrators and Frequency-Locked Loop for Induction Motor Drives

Accurate flux estimation is essential for the implementation of a high-performance ac motor drive. However, it still faces some problems, which can better be projected by analyzing performances of existing flux estimators, implemented with either a pure integrator or a low-pass filter (LPF). To solv...

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Bibliographic Details
Published inIEEE transactions on power electronics Vol. 32; no. 8; pp. 6286 - 6296
Main Authors Rende Zhao, Zhen Xin, Poh Chiang Loh, Blaabjerg, Frede
Format Journal Article
LanguageEnglish
Published New York IEEE 01.08.2017
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects
A C motors
Attenuation
Back electromotive force
Cutoff frequency
Electromotive forces
Estimation
Flux
Flux estimation
Frequency estimation
Frequency locking
Frequency synchronization
frequency-locked loop (FLL)
Harmonic analysis
induction motor (IM) drives
Induction motors
Initial conditions
Integrators
Low pass filters
Low speed
Offsets
Power harmonic filters
second-order generalized integrator (SOGI)
Stators
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Summary:Accurate flux estimation is essential for the implementation of a high-performance ac motor drive. However, it still faces some problems, which can better be projected by analyzing performances of existing flux estimators, implemented with either a pure integrator or a low-pass filter (LPF). To solve the problems, an alternative flux estimator, implemented with a single second-order generalized integrator (SOGI) and a frequency-locked loop (FLL), is discussed for induction motor drives. The SOGI block included in this algorithm works for integrating the back-electromotive force, which unlike the pure integrator and LPF, does not experience saturation and significant dc offsets caused by different initial conditions. The single-SOGI-FLL estimator does not need additional magnitude and phase compensation, while its performance may deteriorate at low speed, caused by the inverse proportional relationship between its estimated flux and the frequency. A multi-SOGI-FLL flux estimator is, thus, proposed for uncompromised attenuation of dc and harmonic errors even under low-speed condition. Excellent flux estimation can, hence, be offered over the full-speed range, as proven through theoretical studies and experiments.
ISSN:0885-8993
1941-0107
DOI:10.1109/TPEL.2016.2620428