Circular Arc Voltage Trajectory Method for Smooth Transition in Induction Motor Field-Weakening Control

In the transition process from the base-speed region to the field-weakening region of induction motor (IM), the voltage margin would suddenly disappear due to the limited inverter voltage. This insufficient voltage margin would deteriorate the current control of IM, causing severe voltage saturation and current ripple. To address this problem, a circular arc voltage trajectory method is proposed with the smooth transition-combined field-weakening controller. The voltage and current behavior are analyzed quantitatively during the transition process. The theoretical analysis shows that the studied circular arc trajectory can suppress the sudden decrease of the voltage increasing rate in the transition region, leading to the reduced voltage saturation and current ripple. The sufficient voltage margin and smooth current can be realized at the cost of <10% voltage utilization ratio. The effectiveness of the studied method is verified by contrast experiments on an ARM-based 3.7-kW IM platform.