A flux observer for a direct torque controlled permanent-magnet synchronous machine control system

To improve performance of the stator flux estimation for a direct torque controlled permanent magnet synchronous motor control system. In this paper, an extended sliding-mode observer is proposed to observe the stator flux linkage of permanent magnet synchronous motor. The parameter choice guidelines are designed to guarantee the global stability of the proposed sliding-mode observer. Then, the equivalent low-pass filter function of the observer is presented to suppress sliding-mode chattering. Compared to the conventional estimator, this observer has better dynamic behavior, disturbance resistance and high accuracy estimation ability. The experimental results verify the effect of this observer.