Optimisation of current harmonics for three-level VSI based induction motor drive suitable for traction application

A method for minimisation of current harmonics spectrum for asynchronous traction motor fed from three-level neutral point clamped voltage-source inverter is described in this study. A selective harmonic elimination and mitigation-based algorithm using particle swarm optimisation has been utilised. Since the load is an induction motor suitable for traction application, a modified objective function with constraint of individual current harmonics has been proposed in this study to obtain improved harmonic elimination and control with low switching frequency. The proposed method has been compared with conventional technique considering only torque spectrum as objective function. Moreover, a suitable formulation for loss calculation has been proposed to optimise both the motor losses and torque harmonics. Suitable simulations along with experiments are performed with a practical induction motor of cage type to justify the proposed method.