State estimation techniques for speed sensorless field oriented control of induction motors

Akın, Bilal
This thesis presents different state estimation techniques for speed sensorlees field oriented control of induction motors. The theoretical basis of each algorithm is explained in detail and its performance is tested with simulations and experiments individually. First, a stochastical nonlinear state estimator, Extended Kalman Filter (EKF) is presented. The motor model designed for EKF application involves rotor speed, dq-axis rotor fluxes and dq-axis stator currents. Thus, using this observer the rotor speed and rotor fluxes are estimated simultaneously. Different from the widely accepted use of EKF, in which it is optimized for either steady-state or transient operations, here using adjustable noise level process algorithm the optimization of EKF has been done for both states; the steady-state and the transient-state of operations. Additionally, the measurement noise immunity of EKF is also investigated. Second, Unscented Kalman Filter (UKF), which is an updated version of EKF, is proposed as a state estimator for speed sensorless field oriented control of induction motors. UKF state update computations, different from EKF, are derivative free and they do not involve costly calculation of Jacobian matrices. Moreover, variance of each state is not assumed Gaussian, therefore a more realistic approach is provided by UKF. In this work, the superiority of UKF is shown in the state estimation of induction motor. Third, Model Reference Adaptive System is studied as a state estimator. Two different methods, back emf scheme and reactive power scheme, are applied to MRAS algorithm to estimate rotor speed. Finally, a flux estimator and an open-loop speed estimator combination is employed to observe stator-rotor fluxes, rotor-flux angle and rotor speed. In flux estimator, voltage model is assisted by current model via a closed-loop to compensate voltage model̕s disadvantages.


State estimation of induction motor using unscented Kalman filter
Akin, B; Orguner, Umut; Ersak, A (2003-06-25)
In this paper, a new estimation technique, unscented Kalman filter (UKF) is applied to state observation in field oriented control (FOC) of induction motor. UKF, a recent derivative-free nonlinear estimation tool, is used for estimating rotor speed and fluxes using sensed stator current and voltages. In the simulations, UKF, whose several intrinsic properties suggest its use over EKF in highly nonlinear systems, turned out to be very similar to EKF in flux estimates. The simulation results also show that UK...
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In this paper, a new approach for the calculation of high-frequency losses in induction motors is presented. The input to the motors is assumed to be supplied from a sinusoidal voltage source. The method is based on the two-dimensional (2-D)). field solutions of the magnetic circuit, obtained by using a nonlinear "harmonic" solution. Hence, the solution time is very short. From the "harmonic" solution, the air-gap field distribution as well as the fundamental frequency eddy current losses are determined. Th...
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Implementation of a vector controlled induction motor drive
Acar, Akın; Ertan, Hulusi Bülent; Department of Electrical and Electronics Engineering (2004)
High dynamic performance, which is obtained from dc motors, became achievable from induction motors with the recent advances in power semiconductors, digital signal processors and development in control techniques. By using field oriented control, torque and flux of the induction motors can be controlled independently as in dc motors. The control performance of field oriented induction motor drive greatly depends on the correct stator flux estimation. In this thesis voltage model is used for the flux estima...
Speed Control by Sliding Mode of Synchronous Motor
Bahi, T.; Lachtar, S.; Soufi, Y.; Lckhchine, S.; Merabet, H. (2011-09-10)
This paper presents the results of a simulation for synchronous motor speed control using a Direct Torque Control (DTC). This technique was object of a deep study for synchronous motor drives instead of precise closed loop speed control. However, this technique presents some problems such as, high influence of the motor parameters. The sliding mode controller is a model-based approach used to improve the robustness of the control law despite this influence and to illustrate the good performance of this tech...
Citation Formats
B. Akın, “State estimation techniques for speed sensorless field oriented control of induction motors,” M.S. - Master of Science, Middle East Technical University, 2003.