5

5.1.1 DIRECT TORQUE CONTROL
These control, was purposed as the most controllers for driving induction motor. Its method of operation have been explained in detailed. It is also shown in this work that it allows the independence and decoupled control of motor torque and motor stator flux. It is apparent that DTC strategy is easier to handle than the flux vector control because voltage modulators and coordinate transformation are not needed, although it introduced some drawback being the high magnitude of torque ripple
5.1.1 DIRECT TORQUE CONTROL
These control, was purposed as the most controllers for driving induction motor. Its method of operation have been explained in detailed. It is also shown in this work that it allows the free and isolated control of motor torque and motor stator flux. It is clear that its strategy is easier to handle than the flux vector control because voltage modulators and coordinate transformation are not needed, although it introduced some drawback being the high magnitude of torque ripple.
5.1.2 Direct torque control with duty ratio fuzzy controller
After all the simulation, this work focused on introducing a modulation in the DTC. A fuzzy logic controller is in charge of controlling this modulation between the selected active state and a null one.
Therefore it has been suggested and deeply described the fuzzy logic controller, which together with the DTC will create the fuzzy logic DTC. The theoretical claim that duty ratio control can reduce torque ripple in DTC control gave acceptable results and reduces the computation burden by skipping unnecessary complex mathematical modeling of the nonlinear systems. By using duty ratio control, a particular motor performance can be achieved at a lower switching frequency compared to the ordinary DTC, which in turn improves the performance of the drive by minimizing the flux harmonics.
5.2 RCOMMENDATION
All recommendation is summarized schematically in the following ideas:
• To develop a new fuzzy controller that will enhance better performance. This new fuzzy controllers should take into account the following ideas:
1. To develop completely an automatic adaptive controller.
2. The controller must be adaptive to any electrical motor.
3. To minimize the electrical noises, which appear in any power drive.
• Develop the torque ripple reduction with fuzzy logic with duty ratio controllers and also with multilevel converters.
• Develop fuzzy logic with duty ratio DTC without sensor implementation that will be sensing two currents, the DC voltage and by means of either Kalman filter techniques or observers.
• Develop and apply different fuzzy logic DTC, not only to induction motors as it has been done in the present work, but also to any electrical motor.