Most of the papers dealing with variable frequency drive (VFD) are concerned with speed control rather than the starting period. This paper is mainly concerned with the starting period. The paper presents a proposed control strategy for VFD to enhance the performance of induction motors during the starting period. The main objective of the proposed control scheme is to provide high starting torque while the starting current is maintained within acceptable limits. This is implemented up to the rated speed. Beyond the rated speed, the objective is to target the steady-state operating point following the nominal torque-speed characteristic of the motor. The capabilities of the proposed control scheme in the two regions are examined, and a good performance is confirmed. This scheme is suitable for motors which need high starting torque and have several starting times per day. |
