Robust adaptive Variable Structure Control of induction motor drives

In this document a new proposal of speed vector control of induction motors based on robust adaptive VSC (variable structure control) law and its experimental validation are presented. This control scheme uses the SVPWM (space vector pulse width modulation) instead of the traditional current hysteresis comparator, because the space vector modulator eliminates the instability risk when the motor works with large loads and provides best quality of the stator currents, maintaining the main characteristics of the original adaptive VSC algorithm: fast response and good rejection to uncertainties and measurement noises. This algorithm has an adaptive sliding gain that reduces the chattering phenomenon that usually appears in the traditional control schemes. Thus, this regulator is compared with the non adaptive SVPWM-VSC and the PI (proportional integral) controller designed in the frequency domain, in order to prove the good performance of the proposed controller. The controllers have been tested using various simulation and real experiments, with and without load, and in the proposed case, taking into account the parameter uncertainties and measurement noise in the loop signal, in the rotor speed and in the stator current. This work shows that the robust adaptive VSC regulator is a good and usable controller, in both adverse conditions and suitable conditions.