Twelve sectors direct torque control for three-level inverter fed induction motor drive

To maintain the reliable operation of induction motor drive the torque ripple (T-R) needs to be reduced. To obtain the T-R reduction, the three-level neutral-point clamped inverter is utilized to drive an induction motor. In this paper, the direct torque control (DTC) method is investigated for the induction motor drive. In proposed DTC method, the voltage vectors (VV) in three-level inverter are divided in twelve sectors for the selection of accurate voltage vector. All the available twenty seven VV are utilized so that the use of three-level inverter can be fully exploited. The twelve sectors distribution increases the switchover frequency of VV which increases the rate of change of VV. With fast change in VV in every sector, the T-R will also change with the same rate. Therefore, the T-R will be reduced from its maximum possible magnitude. The selection of VV maintains the neutral-point balancing and reduces the common-mode voltage. The detail analysis along with appropriate results is provided to substantiate the proposed DTC method.