Bus-clamping-DTC strategy of a three-level-iverter fed induction motor drive with reduced switching frequency and torque ripple

This paper investigates a novel direct torque control (DTC) strategy for induction motor (IM) drives fed by NPC three-level-three-phase inverter. The proposed strategy is based on the basic DTC operation implemented for the IM control using six-switch three-phase inverter (SSTPI). This proposed strategy consists in the synthesis of two vector selection tables suitably arranged considering the bus-clamping technique. Such synthesis depends on the rotation direction of the stator flux vector. The resulting DTC strategy leads to clamp each motor phase during 60° interval in every half cycle of the reference stator flux vector. Simulation results have proven that the bus-clamping-DTC (BCDTC) strategy exhibits high dynamic performance during both transient and steady-state operations. Therefore, a reduction of the inverter switching losses is gained Through the minimization of the switching frequency.