Research On Vector Speed Regulation Of Induction Motor Based On Improved Linear Active Disturbance Rejection Technology

The emergence of vector control allows AC motors to have speed regulation performance comparable to DC motors.However,vector control relies on accurate mathematical models.In the actual process,the perturbation of motor parameters and the coupling between subsystems will cause the motor to fail to meet higher performance requirements under traditional PI control.The Linear Active Disturbance Rejection Controller(LADRC)weakens the controller’s reliance on the precise mathematical model of the controlled object.The parameter perturbation,unknown external disturbance and coupling between subsystems are all regarded as the total disturbance of the system.The feedforward compensation for the total disturbance of the system estimated by the expanded observer realizes the transformation of the mathematical model of the controlled object,so that the transformed controlled object can obtain a better control effect under the traditional control.Although LADRC parameter setting is simple and easier for engineering applications,it is found in actual use that the performance of LADRC is not high enough,so it is necessary to improve LADRC.For LADRC,the accuracy of the estimation of the internal state variables of the system has a greater impact on the performance of the controller.After observing the error between the traditional linear extended state observer(LESO)and the system state variables,the idea of introducing error differentiation to improve the LESO structure is proposed.Compared with the traditional LESO,the improved LESO improves the accuracy of the observation of the internal state variables of the system and speeds up the convergence speed of the observer state variable estimates.Because the improved LESO can accurately estimate the total disturbance of the system including the coupling between subsystems,the electromagnetic torque can be controlled more effectively.The algebraic criterion proves the stability of the improved controller,and compares the two controllers in terms of tracking,anti-disturbance and observation accuracy.Finally,the control effect of the two controllers was verified again by digital simulation software.The vector control will introduce measurement noise in the process of obtaining the motor speed information through the speed measuring device,which will have an adverse effect on the motor control.Although LESO itself has a filtering effect,in order to improve the response speed and observation accuracy of the system,choosing a larger observer bandwidth will weaken the controller’s ability to suppress high-frequency disturbances.Considering that the LESO step increase can not only increase the bandwidth,but also improve the performance of the controller to suppress low-frequency disturbances.Therefore,in order to better suppress the measurement noise,the state estimation output by the observer is subjected to low-pass filtering to improve the high-frequency anti-interference ability of the controller.Theoretical analysis shows that the improved LESO as a band-pass filter has better suppression effect on the measurement noise.From the simulation curve,it can be found that the noise content in the motor speed controlled by the new controller is significantly reduced,which further verifies the effectiveness of the controller.