ROBUST SPEED CONTROL OF BRUSHLESS DIRECT-DRIVE MOTOR USING INTEGRAL VARIABLE-STRUCTURE CONTROL

A robust speed control technique for a brushless direct-drive motor (BLDDM) using a variable structure control (VSC) approach is presented. The significant problems of conventional VSC are investigated in view of the practical implementation and an integral variable structure control with a load torque observer is proposed as an effective way of overcoming these problems. By employing the proposed control scheme, the robustness against the unknown disturbance can be improved in the transient state and the steady-state error can be minimised by an integral action. Furthermore, the reduction of the chattering is also realised by using a load torque observer. The proposed algorithms implemented using the software of TMS320C30 and the effectiveness is verified through the comparative simulations and experiments for the BLDDM driven by a three phase voltage-fed PWM inverter.