A terminal sliding mode control method based on nonlinear disturbance observer is investigated to realize the speed and current tracking control for PMSM drive system in this paper. The proposed method adopts the speed-current single-loop control structure instead of the traditional cascade control in the vector control of PMSM. Firstly, considering the nonlinear and the coupling characteristic, a single-loop terminal sliding mode controller is designed for PMSM drive system through feedback linearization technology. This method can make the motor speed and current reach the reference value in finite time, which can realize the fast transient response. Although the sliding mode control is less sensitive to parameter uncertainties and external disturbance, it may produce a large switching gain, which may cause the undesired chattering. Meanwhile, the sliding mode control cannot keep the property of invariance in the presence of unmatched uncertainties. Then, a nonlinear disturbance observer is proposed to the estimate the lump disturbance, which is used in the feed-forward compensation control. Thus, a composite control scheme is developed for the PMSM drive system. The results show that the motor control system based on the proposed method has good speed and current tracking performance and strong robustness.

To simplify the control structure, improve transient performance and disturbance rejection ability of the permanent magnet synchronous motor (PMSM), a hybrid reaching law (HRL) based sliding mode control (SMC) and a time-varying nonlinear disturbance observer is proposed for the speed-current single-loop control. Firstly, a HRL including variable terminal term and variable exponential term based sliding mode control is proposed. The chattering is analyzed, and the results indicate that the convergence time is effectively accelerated and the chattering is reduced. Then, a non-singular terminal sliding mode speed controller with single-loop structure is designed. The present scheme has better transient response and higher tracking performance. Furthermore, to strength the anti-disturbance ability and eliminate the estimated peak at the initial time, a time-varying nonlinear disturbance observer (TVNDO) is proposed to estimate both matched and mismatched disturbances, respectively, and they are carried out to provide disturbances compensation for the proposed controller. Subsequently, the convergence time is calculated, and the stability of the control system is analyzed and proved by the Lyapunov theory. Comparative experiments indicate that HRL+TVNDO has better speed control performance, such as smaller overshoot, faster transient response, higher control accuracy and stronger robustness under different operating conditions.

Aiming at the speed regulation problem of permanent magnet synchronous motor (PMSM) drives, a novel backstepping nonsingular terminal sliding mode control (BNTSMC) method with finite-time disturbance observer (FTDO) is proposed. In order to ensure excellent tracking and anti-disturbance performance, the backstepping nonsingular terminal sliding mode speed controller based on equivalent motor model and the recursive principle is designed for PMSM. The benefits of this approach are that the controller has asymptotic stability based on backstepping design and strong robustness for the matched disturbance based on sliding mode control. Then, to further improve the anti-disturbance performance, a finite-time disturbance observer is designed, and it is used to estimate the mismatched external disturbance in motor drive system. The stability of the system is also proved with Lyapunov criterion. Finally, the experimental results show that the proposed method has the advantages of fast convergence and strong robustness against parameter variations and external disturbance.

This paper is mainly focusing on the problem of speed tracking control for permanent magnet synchronous motor (PMSM) drive system subject to matched and mismatched disturbance. This is achieved by a novel Port-Controlled Hamiltonian control method with nonlinear disturbance observer. Different from the traditional speed-current cascade control for PMSM, the speed-current single loop controller is designed. Firstly, the Port-Controlled Hamiltonian model of PMSM is established, then the Hamiltonian speed controller is designed by using interconnection assignment and damping assignment method. However, the standard Hamiltonian controller cannot achieve the satisfying behavior in the presence of the parameter variations and external disturbance, thus a nonlinear disturbance observer is designed to estimate the lump disturbance of the system, which is used to the feed-forward compensation control. Finally, simulation and experiment on the speed control system of PMSM are implemented. The results show that the proposed method has fast speed control performance and strong robustness for the different disturbance.