60° bus-clamping based DTC strategy dedicated to three-level inverter fed induction motor drives

The paper is devoted to the synthesis and performance analysis of a direct torque control (DTC) strategy, based on the bus-clamping technique, dedicated to three level NPC inverter fed induction motor drives. The principle of the proposed strategy consists in keeping the voltage vector of each motor phase during 60° of the half of a cycle of the reference stator flux vector. The synthesis of the vector selection tables (one for clockwise rotation and the other for anti-clockwise rotation) is achieved on the basis that enables the fulfilment of the control combinations related to the variations of the stator flux and the electromagnetic torque, along with a reduction of their ripples. Simulation results highlight the torque high dynamic as well as reduced ripple, exhibited by the three level NPC inverter fed induction motor drive under the control of the proposed bus-clamping DTC strategy.