International Journal of Power Electronics and Drive Systems (IJPEDS) Vol. 16, No. 1, March 2025, pp. 457~463 ISSN: 2088-8694, DOI: 10.11591/ijpeds.v16.i1.pp457-463  457 Journal homepage: http://ijpeds.iaescore.com Enhanced torque control in high-speed DTC using modified stator flux locus Syed Abrar S. A. Zawawi 1,2 , Auzani Jidin 1,2 , Nurul Syahada Muhamad Sabri 1 , Siti Azura A. Tarusan 1 , Tole Sutikno 3,4 1 Faculty of Electrical Technology and Engineering, Universiti Teknikal Malaysia Melaka (UTeM), Melaka, Malaysia 2 Power Electronics and Drives Research Group, CeRIA, UTeM, Melaka, Malaysia 3 Department of Electrical Engineering, Faculty of Industrial Technology, Universitas Ahmad Dahlan, Yogyakarta, Indonesia 4 Embedded System and Power Electronics Research Group (ESPERG), Yogyakarta, Indonesia Article Info ABSTRACT Article history: Received Sep 18, 2024 Revised Nov 21, 2024 Accepted Dec 26, 2024 This paper proposes a modification of stator flux locus in direct torque control (DTC) of induction machine, aiming to enhance torque capability during steady-state operation at high speeds. The modified flux locus maintains the simplicity of the original DTC structure and its advantages of rapid torque and flux dynamic control. However, DTC faces challenges in controlling motor torque at high-speed operations. This study addresses the limitation of the traditional circular flux locus, which limits the angular frequency of stator flux to increase further and hence causes control of torque deteriorates at high speeds. By modifying the stator flux locus from a circular to a hexagonal shape by adjusting flux hysteresis band, this can improve torque control during high-speed motor operation. This finding has potential applications in industrial and electric vehicle sectors that demand enhanced torque control for high-speed motor operations. Keywords: Direct torque control Hexagonal flux locus High-speed motor Three-phase induction motors Torque ripple reduction This is an open access article under the CC BY-SA license. Corresponding Author: Auzani Jidin Faculty of Electrical Technology and Engineering, Universiti Teknikal Malaysia Melaka (UTeM) Durian Tunggal, Melaka 76100, Malaysia Email: auzani@utem.edu.my 1. INTRODUCTION Induction motors is well-known across various industrial, commercial, and domestic applications due to its robustness, reliability, and cost-effectiveness [1], [2]. As industries evolve and demands for high- performance motor control increase, achieving efficient and precise control over these motors becomes critical. Among the advanced control strategies, direct torque control (DTC) is renowned for its simplicity, fast dynamic response, and robustness [3], [4]. DTC for induction motor drive was originally proposed by Takahashi and Noguchi [5] and Depenbrock [6], DTC is widely used in variable frequency drives for induction motors as it eliminates the need for coordinate transformations and complex control structures, unlike field-oriented control (FOC) [5]–[8]. Despite its advantages, traditional DTC faces challenges, particularly in high-speed operations. One of the primary challenges in high-speed DTC is the high torque ripple and variable switching frequency [7]. The use of hysteresis controllers for torque and flux regulations is the primary cause of these problems, which can cause undesirable oscillations in motor performance [9]–[11]. Additionally, the hysteresis-based flux and torque control scheme can lead to variable switching frequencies, which can result in increased electromagnetic interference and motor heating issues [12]. At high speeds, maintaining steady-state performance and achieving precise torque control become even more difficult [13]–[15].