A new approach for robust digital position control of brushless direct drive motor with load torque observer

Abstract

A new control approach for the robust position control of a brushless direct drive (BLDD) motor is presented. The linear quadratic controller plus load torque observer is employed to obtain the robust BLDD motor system approximately linearized using the field-orientation method for an AC servo. And the state space analysis is performed to obtain the gains systematically. In addition, the robustness is also obtained without affecting the overall system response. The load disturbance is detected by a 0-observer of the unknown and inaccessible input, and is compensated by the feedforward without requiring the noisy current information. All these designs are simply done in the state space. Finally, the overall system is controlled by using a microprocessor in the z-domain.