Torque sensorless control of induction motor

In this paper the torque and speed sensorless induction motor (IM) control is presented. The main idea consists in utilizing the best qualities of the both nonlinear structures of the motor observer and the current controller. Motor observer is based on flux error between modeled and measured quantities. In addition, the rotor flux observer is using combination of the feedforward and feedback terms in order to enhance the sensitivity of the observer. Torque and stator current control as well as the rotor flux observer are based on the sliding mode theory, which results in high degree of robustness towards parameters variation and the external disturbances. Proposed control scheme is implemented on DSP system extended with FPGA where event-driven current controlled modulator is realized. DSP serves for time discrete speed control and observer, while time critical current control is implemented on FPGA. Results demonstrate high efficiency of the proposed estimation and control method.