Direct Torque Control Technique of Nine-Phase Induction Motor by Aligning the Stator d-axis with the Stator Flux-linkage Vector

The paper presents a direct torque control (DTC) technique for a nine-phase induction motor (IM). In the given technique, the d-axis of the stator aligned with the stator flux-linkage vector. By aligning the d-axis of the stator with the stator flux-linkage vector, the magnitude of the stator flux-linkage vector becomes equal to the d-axis stator flux component, and the q-axis stator flux component becomes zero. Thus, it makes the electromagnetic torque of the nine-phase IM proportional to the d-axis component of stator flux and the q-axis stator current component. The d-axis flux magnitude can be directly controlled by applying the desired d-axis stator voltage component. The q-axis stator current component can be directly controlled by applying the desired q-axis stator voltage component. The mathematical analysis is presented in the paper for DTC of nine-phase IM by aligning the d-axis with the stator flux-linkage vector. The simulation results of MATLAB/Simulink software environment are also presented in the paper to further justify the DTC of IM. The performance of the nine-phase IM is tested by subjecting the motor to speed change operation on loaded conditions.