Minimization of torque ripples and speed control of switched reluctance motor through fuzzy logic based direct torque control method

The switched reluctance motor has a salient pole stator with concentrated coil and a salient pole rotor which has no winding on it. The motor's doubly salient structure makes its magnetic characteristics highly nonlinear. The switched reluctance motor gains a significant response in industries in the past decade because of its ruggedness, high torque to inertia ratio, simple structure, high reliability and inexpensive manufacturing capability. These features make it a suitable candidate for various applications and electric drives. However in the field of electric drives a switched reluctance motor drive is having doubly salient structure thus it inherently produces high torque ripples and acoustic noise problems and its controlling difficulties that is an undesirable effect for vehicle applications, especially at low speeds. The control of the SRM is also a difficult task. The motor's doubly salient structure make its magnetic characteristics nonlinear. The flux linkage appears to be a nonlinear function of stator current as well as rotor position. Apart from these for suitable control the SRM should be operated in continues phase to phase switching mode. The main objective of this thesis is to form and test SRM drive to provide a detailed work in this field. First a literature study for switched reluctance motor is carried out which includes its fundamental operation, modelling, and Torque ripple reduction is done from the motor's structure properties, model equations, operations and converter topologies. And secondly, a fuzzy logic controller based direct torque control method is used for speed controlling and for controlling of torque ripples of the 8/6 SRM drive. Modelling and application of fuzzy logic controller based direct torque control method is done in MATLAB/SIMULINK environment.