Control design of a dual three-phase induction motor

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master_Valiyaveettil_Sadanandan_Nithin_2025.pdf (3.84 MB)

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School of Electrical Engineering | Master's thesis
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Date

2024-12-26

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Major/Subject

Electrical Power and Energy Engineering

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Degree programme

Master's Programme in Automation and Electrical Engineering

Language

en

Pages

97

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Abstract

The need for high-power, high-speed electric machines has increased with the development of technologies like electric ships and aircraft. Multi-phase machines are becoming a practical alternative to three-phase motors due to their better fault tolerance, higher efficiency, and greater flexibility. However, applying rotor-flux-oriented vector control, which is well-established for three-phase motors, to six-phase motors introduces new challenges, especially under unbalanced conditions. Understanding how unbalanced currents generate radial suspension forces is also a critical area that requires further study. This thesis develops a rotor-flux-oriented vector control method for a six-phase induction motor (IM) designed to operate multiple pole-pair fields. A continuous-time motor model was created using the inverse-gamma structure and vector space decomposition to describe motor dynamics accurately. The control system included two-degree-of-freedom (2DOF) PI controllers for regulating speed and current. This allowed precise torque control in the main harmonic plane while maintaining controlled current unbalance to study the radial suspension forces. The proposed method was tested using MATLAB/Simulink simulations and validated by comparing results with benchmark values and finite element models. Under balanced conditions, simulations showed accurate speed and current control. When operating under unbalanced conditions, the control system successfully facilitated the study of radial forces. Experimental tests at low speeds further confirmed the reliability of the current control strategy. By modeling and analyzing radial suspension forces, future research could explore replacing mechanical bearings with suspension forces, potentially increasing motor speeds and improving efficiency by reducing mechanical limitations.

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Supervisor

Belahcen, Anouar

Thesis advisor

Mustafa, Bilal

Keywords

electric drive, 6-phase induction motor, combined winding, 3-phase two level inverter, vector control, rotor-flux orientation

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https://urn.fi/URN:NBN:fi:aalto-202501282063

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