Danqi Xiang

To improve the disturbance-rejection performance of the permanent magnet synchronous motor (PMSM) cascade speed control system under voltage saturation constraints (VSCs), a reference current-corrected disturbance observer (RCCDOB) method is proposed. This method first integrates the linear current loop dynamics (CLD) into the disturbance observer to minimize the impact of current tracking errors on speed loop disturbance compensation. Then, an anti-windup auxiliary system is designed to correct the reference current in order to convert the VSC into a current control input constraint, addressing the saturation nonlinearity in the CLD. Furthermore, based on this auxiliary system, an RCCDOB speed control structure is developed to enhance the robustness of the system under VSC and disturbances. The stability analysis and design procedure of the RCCDOB control system are also presented. The comparative experiment with other competitive methods in disturbance rejection verifies the effectiveness of the proposed method.

Parameter identification is a critical factor influencing the dynamic performance of permanent magnet synchronous motor (PMSM)-driven servo systems. However, mechanical parameter identification encounters the following challenges: multiple parameters that are significantly mutually coupled and difficulties in direct measurement, especially with friction parameters. Currently, most scholars have navigated these challenges through partial parameter identification, either by ignoring Coulomb friction, neglecting the dynamic processes of Coulomb friction, or identifying only the parameters associated with the friction model. In this study, a scheme using a parallel-cascaded extended sliding-mode observer (PCESMO) is proposed to address these challenges. The PCESMO relies solely on phase currents and rotor position to identify parameters, including the moment of inertia, viscous damping, load torque, and parameters of a simplified LuGre model that considers the dynamic process of Coulomb friction during self-commission. Additionally, the PCESMO has low computational complexity and is easy to implement. The effectiveness of the PCESMO was validated through both simulations and experiments. Compared to other competitive methods, PCESMO-identified parameters result in optimal control effects.

An identification method is presented for the arctan two-parameter model, which describes the deadtime effect voltage error of PMSM drives' three-phase voltage source inverter (VSI) during self-commission. In this method, the motor maintains a standstill during the whole identification process. First, a disturbance observer is used to improve the tracking performance of the total voltage error. Then, a technique is used to extract the deadtime effect voltage error from the total voltage error without a voltage sensor during the standstill condition. Finally, the core algorithm (utilizing the bisection method) is developed to solve the coupling problem in the two-parameter identification process, such that the parameters in the model converge simultaneously. Furthermore, a sufficient condition for the convergence of the algorithm is given, and a mathematical proof is presented. Experimental results show that the deadtime effect voltage error estimated by our method is closer to the measured voltage error than other state-of-the-art methods proposed in the literature.