DSP-Based speed adaptive flux observer.T is widely used for induction motor drives. This method needs a speed sensor such as a shaft encoder not only for speed control but also for torque control. Although the direct fieldoriented control method with a flux estimator, which uses a pure integrator, does not need the speed sensor for torque control, this method is not practical. This is because the flux estimator does not work well in a low speed region. The pole of the flux estimator is on the origin of the s plane, and it is very sensitive to the offset of the voltage sensor and the stator resistance variation. torque control, this method is not practical. This is because the flux estimator does not work well in a low speed region. The pole of the flux estimator is on the origin of the s plane, and it is very sensitive to the offset of the voltage sensor and the stator resistance variation.