DSP-based secondary flux controlled high precision torque control of induction motor.

Abstract

In the field of industrial drives, the vector control of the induction motor has been widely used to achieve the high performance torque control. In this paper, a new high precision torque control of the induction motor has been proposed. The control strategy proposed here is developed according to the conventional vector control law, but it has a feature that the secondary is controlled directly by selecting the appropriate voltage vector of the voltage-fed inverter.The prototype was constructed using a 2.2kW induction motor where the torque control was implemented by software of DSP-TMS 32010. All control processing including the identification of the rotor resistance could be executed within 100μs. From the experimental results, the linear relationship between torque and slip frequency was established for the wide frequency range from rotor rocked condition to 50Hz. Due to identification of rotor resistance, the accuracy of the torque control within ±2% was obtained regardless of the temperature change of the motor.