PROJECT TITLE :

Generalized DTC Strategy for Multilevel Inverter fed IPMSMs with Constant Inverter Switching Frequency and Reduced Torque Ripples - 2017

ABSTRACT:

This paper proposes a generalized direct torque control (DTC) strategy for multilevel inverter fed DTC (MLI-DTC) drives. By using a straightforward voltage vector decomposition technique, the proposed methodology is compatible with inverters possessing any variety of voltage levels. Consequently, voltage vectors are applied in an exceedingly similar means as within the case of a 2-level inverter fed DTC. A constant inverter switching frequency is imposed in the proposed methodology by employing a torque regulator in place of the ancient torque hysteresis controller, that permits the application of 2 voltage vectors at intervals one switching cycle. This conjointly contributes to cut back the torque and flux ripples. Detailed design pointers for the proposed torque regulator are provided. Experimental results obtained with a 3-level neutral point clamped inverter show that the proposed MLI-DTC drive operates with low, constant switching frequency whereas alleviating torque and flux ripples under all operating conditions. Comparative study with a prior art and parametric sensitivity analysis are presented to verify the effectiveness and robustness of the proposed MLI-DTC method.