Direct torque control scheme of IM drive with 12-sided polygonal voltage space vectors

The application like electric vehicles requires frequent torque control to control speed of IM Drives. The direct torque control is very good control scheme for fast torque control and it is easy to implement and decoupling of motor variables along rotor flux axis is not required. In this paper, direct torque control scheme is proposed using 12-sided polygonal space vector based inverter fed IM drive. The proposed DTC scheme uses the fundamental stator voltage vector for identification of sector for selection switching of vector to control stator flux and the torque. Because the DTC scheme requires the information of sector of stator voltage vector position only. The exact position of stator voltage is not required for control like rotor oriented vector control scheme of IM drives. Extensive simulation and experimental results are shown to verify the proposed concept. The control scheme is extended from 1 Hz to rated 50 Hz operation of the inverter. The advantages achieved due to 12-sided polygonal space vector are mainly fast transient of torque, less switching frequency variation, reduced torque error and high resolution of sector identification with accuracy of ±15°.