Weighting-Factor-Free Predictive Torque Control Structures for 3L-NPC Inverter-Fed Induction Motor Drives

This paper investigates weighting-factor-free predictive torque control (PTC) strategies for induction motor drives supplied by a three-level neutral-point-clamped (3L-NPC) inverter. Three predefined switching-table-based schemes—PTC-ST1, PTC-ST2, and PTC-ST3—are proposed to eliminate weighting-factor tuning and online optimization. The methods are comparatively evaluated in terms of RMS torque and flux ripples, DC-link capacitor voltage deviation, stator current THD, switching losses, and computational complexity measured by the normalized event count (NEC). Simulation studies carried out in the MATLAB/Simulink environment confirm that PTC-ST2 achieves superior capacitor voltage balancing at the expense of torque performance, whereas PTC-ST1 ensures robust and balanced behavior across operating conditions. Overall, PTC-ST3 provides the most favorable compromise between torque quality, current harmonics, and implementation efficiency, making it suitable for high-speed drives with strict real-time constraints.