This paper presents a new contribution the domain of sensorless speed control of
doubly-fed induction generator in wind turbine applications. Where the speed and the
dynamic torque are estimated and used to feedback the control loops. The proposed
sensorless algorithm is robust to variations of the values of machine parameters where the
estimated speed is independent of them. The algorithm avoids using differentiation which
significantly improves its immunity to noise. The field oriented vector control theory is
used to control the speed of the doubly fed induction machine. The used controllers in
closed loops are classical proportional integral (PI). The modeling is based on the Park
equations of the induction machine and on a simple model of the three phase inverter. The
results of simulink on MATLAB provide good performance of the sensorless speed
control.
The presented paper deals with an implemented speed sensorless direct vector control (DVC) technique based on stator flux orientation algorithm to estimate and control rotor speed of three phase induction motor (IM). The driver system is presented in
this paper has a three phase bridge uncontrolled rectifier and space vector pulse width modulated (SV-PWM) inverter to drive and control the speed of the (IM) at different mechanical load conditions. The rotor speed has been obtained by slip frequency estimation instead of use feedback speed sensor. The structure of Volt/Freq via PI-controller is used to control and adjust speed accuracy between required and estimation rotor speed to precise speed response. The proportional and time integration controller values obtain by Ziegler-Nichols closed-loop tuning method. Computer simulation results with Matlab/Simulink program show an acceptable speed control response, minimum error at steady state and dynamic condition, a results show also the stator voltage, current and flux estimated in direct-quadrate of stationary and synchronous reference frame at variation in load up to (10 N.m) beside the synchronous, slip and rotor speed estimation are varied between (250-1486 rpm).
Keywords: Induction Motor Drive System, Direct Vector Control, Speed Sensorless.
