High Performance Speed Control System of Vector Controlled Induction Motor with Load Torque Observer

Abstract

Vector Controlled Induction Motors (VCIM) have been increased in popularity and their application fields are expanding. In this paper, the software implemented high performance control system of VCIM with torque feedforward using load torque observer is presented. In the proposed system, load torque is estimated by the minimal order state observer based on torque component of VCIM, and the robust control system against load torque variation is realized using the torque feedforward. Moreover, the design of speed controller with the torque observer is discussed.
The prototype was constructed using a 3.7 kW induction motor and an eccentric load with an arm and a weight which produced sinusoidal gravitational torque. The whole processing (vector control including current loop, speed control and observer control) could be performed within 104 μs by DSP-TMS 32010. Experimental results showed the improvement of speed control characteristics, the robustness of control loop against system parameters change and the improvement of disturbance suppression in low frequency range.