Hysteresis‐Based Voltage Vector Control for Slip‐Speed‐Driven DFC of a Five‐Phase Induction Motor

ABSTRACT Direct Torque Control (DTC) is widely used in industrial motor applications due to its fast dynamic response and simple structure; however, it suffers from notable drawbacks such as high torque ripple, flux ripple, and variable switching frequencies across different operating speeds. This paper presents a slip speed controller‐based direct flux control (SSC‐DFC) scheme for a five‐phase induction motor, in which slip‐angle–based stator flux angle correction is explicitly combined with a voltage‐based hysteresis controller (HVC). In the proposed scheme, the reference stator flux angle is corrected by injecting the slip angle, which is obtained by integrating the slip speed generated from speed and torque control loops. The corrected stator flux angle, together with the stator flux reference magnitudes, generates the reference stator flux vector, which is compared with the estimated flux to generate the reference voltage vector. This reference voltage vector directly selects the appropriate switching state through a hysteresis voltage controller with a simplified lookup table, thereby making fast voltage vector transitions to reduce torque and flux ripple. Consequently, the proposed SSC‐DFC scheme replaces the conventional hysteresis flux controller and torque controller with the reference voltage vector‐based hysteresis controller without disturbing the general structure of hysteresis‐based DTC techniques. In the proposed control scheme, the torque regulation is achieved through flux angle control, whereas stator flux control is achieved through reference flux magnitude control, enabling unified control of both torque and flux using a single voltage vector selection mechanism. The proposed SSC‐DFC scheme is tested on a 5‐phase induction motor test rig and experimental results show significant reduction in the torque and flux ripples, lower phase current harmonic distortion; and constant switching frequency for a wide speed range compared with conventional DTC control schemes.