Novel Voltage Trajectory Control for Field-Weakening Operation of Induction Motor Drives

This paper proposes a new voltage trajectory control for the field-weakening operation of induction motor drives. The presented method does not require a lookup table and reduces the parameter sensitivity. Moreover, the dc-link voltage utilization can be extended such that the voltage can reach the hexagon trajectory of the space vector of the voltage. The difference between the switching period and the summation of active switching times for inverter pulsewidth modulation control is used for field-weakening control. As the summation of the active switching times is less than its switching period, constant torque is retained. In contrast, the field-weakening control is considered. Smooth and automatic transition between two field-weakening regions can be achieved by the calculated q-axis current subjected to the voltage, current, and maximum pullout torque constraints. Experimental and simulation results will be presented to fully support the claims.