Open AccessComparison of high‐order and second‐order sliding mode observer based estimators for speed sensorless control of rotor‐tied DFIG systems
Author(s) -
Mbukani Mwana Wa Kalaga,
Gule Nkosinathi
Publication year - 2019
Publication title -
iet power electronics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.637
H-Index - 77
eISSN - 1755-4543
pISSN - 1755-4535
DOI - 10.1049/iet-pel.2018.6225
Subject(s) - control theory (sociology) , observer (physics) , estimator , rotor (electric) , mode (computer interface) , doubly fed electric machine , computer science , order (exchange) , control (management) , control engineering , engineering , mathematics , physics , artificial intelligence , ac power , voltage , statistics , economics , mechanical engineering , electrical engineering , quantum mechanics , finance , operating system
In this study, a sensorless vector control for the rotor‐tied doubly fed induction generator (RDFIG) is proposed in the grid‐connected mode. The proposed sensorless vector control method includes a slip speed/angle estimator which is based on the association of the high‐order sliding mode observer (HOSMO) with a phase‐locked loop (PLL). In addition, an extensive comparison between the PLL‐based HOSMO estimator and the PLL‐based second‐order sliding mode observer (SMO) estimator is also presented. The Lyapunov stability criterion is used to determine both observer gains to allow their convergence in finite time. Both the proposed HOSMO and the SMO use the three‐phase stator current and back‐electromotive force (EMF) as state variables which enable the start of the estimation even before the machine is connected to the grid. The proposed HOSMO takes into account the dynamics of the back‐EMF space vector. The PLL is used to extract the estimated slip speed/angle from the estimated back‐EMF. The performance of the proposed sensorless vector control strategy is validated experimentally with a 5.5‐kW custom‐designed RDFIG on a test bench based on the National Instrument (NI) PXIe‐8115 real‐time controller.