tailieunhanh - Challenges and Paradigms in Applied Robust Control Part 9

Tham khảo tài liệu 'challenges and paradigms in applied robust control part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Discussion on Robust Control Applied to Active Magnetic Bearing Rotor System 229 a Robust Ha controller s 150 c s a 150 100 50 0 50 100 8 6 4 2 1 4 0 2 3 5 Time s 10 b LPV controller Fig. 16. Rotor acceleration responses. point of 6500 rpm where the system crosses the first flexible mode. The second point where the system experiences oscillations is close to the maximum speed and it can be explained by the deceleration of the rotor. The LPV controller has a lower magnitude of oscillations around this point the difference is 35 . Such a behavior can be explained by an adaptive nature of an LPV controller. In each step the gains are modified according to the rotational speed. During the acceleration process the system does not have enough time to adapt. This results in a higher amplitude of oscillations. During the later deceleration phase the coefficients do not change that fast and performance is better. The speed of the parameter variation is a significant problem for the LPV controllers and usually the main point of conservatism in that approach Leith Leithead 2000 . The second simulation experiment in the steady state proves that LPV controller provides a better performance. In this experiment a step disturbance to the x channel of the rotor A-end is applied at the maximum rotational speed. The simulation results are presented in Fig. 17. The magnitude of the disturbance response for an LPV controller is about three times smaller than that of a robust controller. Additionally the LPV controller does not have coupling between different ends so the disturbance does not propagate through the system. 6. Real-time operating conditions The AMB-based system requires hard-real time controllers. In the case of a robust control strategy the control law is of higher complexity than other solutions. Therefore the implementation of the control law must fulfill the requirements of the target control system such as finite precision of the arithmetic and number format and .