Design and Simulation of Fuzzy Logic Based Self-Tuning Pi Controller for Permanent Magnet Synchronous Motors

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This thesis presents the methods used in speed control of permanent magnet synchronous motor drives. PI control is used as speed controller for permanent magnet synchronous motor in high performance drive system. For the linear system, PI controller is easily tuned and perfectly controls the system with good performance. PMSM is non-linear system by nature. However, PI controller is sensitive to uncertainty of the model, parameter variation and load disturbance. The conventional approach to these issues is to tune the proportional and integral gains manually by observing the response of the system. The well-known conventional approach, Ziegler-Nichols method to tune the coefficient of a PI controller is very simple but cannot guarantee to be always effective to avoid tedious tasks in manual control. The tuning of PI parameters should also be done on-line for better performance. This thesis presents design of self-tuning PI controller schemes based on fuzzy logic approach. The performance of proposed controller was tested at different operating conditions of reference speeds as well as with load variations through simulations using matlab/Simulink software package. The simulation results reveal, for no-load torque over shoot is 34.85 % and 3.38 % for PI-controller and proposed controller respectively. When 0.25Nm load is applied at 0.02sec, over shoot is 32.9 % and 3.56 % for PI and Fuzzy logic based self-tuning PI controller. The simulations results also show that the speed response of proposed controller is not altered by small change in load torque and parameter variations. When the values of stator resistance and inductance is increased by 50%, speed response shows 31.97% and 34.64% overshoot with conventional PI, where as 3.84% and 0.99% overshoot with proposed controller respectively. Further, the designed controller works well even when the reference speed is changed to more complex trajectory which means that, the developed controller speed regulation is unaltered by the nature of reference speed trajectory. These shows remarkable transient response performance improvement compared to conventional PI controller.



PMSM, Self-tuning PI-controller, PI-controller, Fuzzy logic, Matlab/simulink