[align=center]Feedback Linearization Control of Motor with Torque Disturbance Estimation Liu Dongliang Zhou Guangzhou (College of Electrical Engineering, Zhejiang University, Hangzhou, 310027)[/align] Abstract Based on the nonlinear dynamic mathematical model of a permanent magnet synchronous motor (PMSM), the input-output linearization of the PMSM system is achieved using the direct feedback linearization method. Through this linearization model, a speed tracking control law is designed, which, under the condition of ensuring the stability of the entire closed-loop system, improves the celerity of speed tracking. Furthermore , the observer of disturbance torque is applied, reducing the effect of torque disturbance on speed. The simulation results show that the designed method is simple and has better speed tracking performance. Keywords: PMSM, Direct feedback linearization, Disturbance Torque Estimation In addition, a load torque disturbance observer was adopted to reduce the impact of load disturbance on speed. Simulation shows that the feedback linearization control design is simple and has good speed tracking performance. Keywords : Permanent magnet synchronous motor, direct feedback linearization, torque disturbance estimation 1 Introduction With the development of permanent magnet magnetic materials, semiconductor power devices and control theory, permanent magnet synchronous motors (PMSMs) are playing an increasingly important role in current medium and small power motion control. They have the following advantages: compact structure, high power density, high air gap flux and high torque-to-inertia ratio. Therefore, they are increasingly widely used in servo systems. In addition, a permanent magnet synchronous motor is a nonlinear system, which contains a product term of angular velocity and current. Therefore, to obtain accurate control performance, angular velocity and current must be decoupled. For high-precision speed tracking control problems, load disturbance will affect speed fluctuation. Therefore, it is necessary to estimate the load disturbance to reduce its impact. In the past ten years, nonlinear control theory based on the feedback linearization idea has made great progress [1]. Through coordinate transformation and state feedback, nonlinear systems can be transformed into linear systems. Reference [2] details the principle of direct feedback linearization and conducts preliminary research on induction motor control. Reference [3] applies feedback linearization theory to speed tracking control of linear permanent magnet synchronous motor. Direct feedback linearization (DFL) is a feedback linearization method based on system input-output description, which has successfully solved a variety of nonlinear control problems [4-5]. The advantage of direct feedback linearization is that the mathematical tools used are simple, the physical concepts are clear, and it is easy to master. This paper applies the principle of direct feedback linearization, starts from the output equation of the system, performs coordinate transformation and state feedback, decouples the current and angular velocity of permanent magnet synchronous motor, and thus realizes the linearization of the motor control system. The speed tracking control of permanent magnet synchronous motor is simulated using linear control theory. In addition, the influence of load disturbance on speed fluctuation is reduced by designing a load torque disturbance observer [6]. 2 Feedback linearization of permanent magnet synchronous motor 2.1 Mathematical model The permanent magnet synchronous motor with surface model is based on the synchronous rotating rotor coordinate model [7] as follows: 2.2 Coordinate transformation In order to achieve system decoupling and avoid the zero dynamic system problem [8], ω, i[sub]d[/sub] are selected as the output of the system, and the new output variable is defined as: Since the system is a three-input three-output system and its relative order is {1,1,1}, that is, its sum is equal to the order of the system, the system can be linearized by feedback and there is no zero dynamic problem. Let the assumed control quantity be: In this way, the state feedback control can be designed according to the pole placement theory of linear system as: Substituting equations (1), (2), and (3) into (7) and (8), the actual control quantities u[sub]q[/sub] and u[sub]d[/sub] are obtained: 3 Load disturbance observer design In some high-precision servo systems, load disturbance will change, causing speed fluctuations, which will lead to a decrease in the servo performance of the system. Therefore, in high-precision speed tracking control, it is necessary to estimate the load disturbance and compensate it online in real time. The designed load disturbance observer is shown in Figure 1. 4 System Example Simulation The block diagram of the direct feedback linearized control of the permanent magnet synchronous motor based on torque disturbance estimation is shown in Figure 2. The system reaches a satisfactory configuration point by adjusting the parameters. The parameters of the permanent magnet synchronous motor are shown in Table 1. Assuming the reference speed is 500 r/min, a sudden load of 20 Nm is applied in 0.2 seconds. The direct feedback linearized control parameters are as follows: The simulation is shown in Figure 3. A partial magnification of the circle in Figure 3 is shown in Figure 4. Curve 1 in Figure 4 is the speed tracking curve under DFL control, and curve 2 is the DFL speed tracking curve with torque disturbance estimation. The simulation results show that DFL control enables the system to achieve fast speed tracking while ensuring good dynamic performance. At the same time, DFL control with torque disturbance estimation can further accelerate the system's tracking speed and reduce the impact of disturbances on speed fluctuations. [align=center] [/align] 5 Conclusions and Implementation To implement the direct feedback linearization control method based on load disturbance estimation, the TMS320LF2407 DSP chip for motor control was selected as the digital controller, and corresponding software was developed for implementation. As shown in Figure 5, the timer interrupt subroutine is used to implement the direct feedback linearization control strategy and generate SVPWM. This paper applies the direct feedback linearization control based on torque disturbance estimation to the speed tracking of a permanent magnet synchronous motor. This design method reduces the adjustment parameters and simplifies the control design of the system. Matlab simulation shows that the system has good tracking performance, verifying the effectiveness and feasibility of the system design. In addition, this control strategy has been applied to the key project of Zhejiang Province: Intelligent Control System of Flatbed Sewing Machine Based on DSP Control. It shows that the adjustment parameters are relatively reduced compared to PID, the parameter tuning is easier, the programming work is reduced, and the system has achieved good results. References 1 Feng Guang, Huang Lipei, Zhu Dongqi. High performance control of induction motor based on auto-distrubance refection controller [J]. Proceedings of the CSEE, 2001, 21(10): 55-58 2 Zhang Chunpeng, Lin Fei, Shong Wen Chao, et al. Nonlinear control of induction motors based on direct feedback linearization [J]. Proceedings of the CSEE, 2003, 23(2) 3 Zhang Chunming, Guo Qingding. Feedback-Linearization based control of speed tracking for AC linear permanent magnet synchronous servo motor [J]. Journal of Electrical Engineering, 2003, 18 (3) 4 H. Sira-Ramirez, M. 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