Bus-Clamping-Based DTC: An Attempt to Reduce Harmonic Distortion and Switching Losses

This paper deals with a new direct torque control (DTC) strategy based on the bus-clamping technique dedicated to induction motor drives. The 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. Therefore, a reduction of the inverter switching losses is gained. Furthermore, it has been found that the proposed DTC strategy offers a lower harmonic distortion of the motor phase currents and a higher capability to operate at low levels of the dc-bus voltage, which could be of interest for electric vehicle (EV) and hybrid electric vehicle (HEV) applications. These performances are confirmed by simulation and validated by experiments.