ROBUSTIFYING CASCADE PI-PI CONTROLLER OF PERMANENT MAGNET SYNCHRONOUS MOTORS BY DISTURBANCE OBSERVERS

Abstract

Nowadays, Permanent Magnet Synchronous Motors are most commonly used for their high- performing role in industrial applications. Even though in comparison with other motors, their efficiency and dynamic performance are higher, they are also affected by disturbances because of some characteristics (cogging torques, load torques, friction torques, dead time effects). Considering an easy,adjustable and powerful robust control technique Disturbance Observer is extensively used for disturbance estimation. In DOB, internal and external disturbances are evaluated applying verified dynamics and perceptible conditions of plants, whereas the robustness is merely executed by feedback of estimated disturbance. Primary aim in this thesis is to design a disturbance observer in frequency domain for uncertain permanent magnet synchronous motor by applying a complete toolbox is known as Disturbance Observer - Design & Analysis Toolbox (DO-DAT). DO- DAT is enabled to design the Q filter assuring robust stability with expected nominal performance. After several straightforward steps of experiment, observer gains are suggested in this system. Simulations and experimental results on a 300W PMSM testbed substantiate the cogency of the suggested disturbance observer of the system. Apart from the conventional method of designing disturbance observer, this method is user-friendly and accurate. From theoretical methods and modeling, it has been observed that they are not able to assure the robust stability and expected nominal performance. Today’s world needs Scientific methods and concurrent commercialization. If this method is applied for industrial application, it will meet the increasing requirements. It will be cost-effective, simple- to- implement and advantageous because this method is more reliable and flexible for its specific characteristics.