Fast Terminal Sliding Mode Current Control With Adaptive Extended State Disturbance Observer for PMSM System

This article proposes a current decoupling control strategy by combining a fast terminal sliding mode control (FTSMC) and an adaptive extended state observer (AESO). First, the voltage errors and external disturbances caused by $d$ – $q$ -axis current coupling and motor parameter variations are regarded as the lumped disturbance of the system, which facilitates the decoupling of $d$ – $q$ -axis currents. Next, an equivalent control-based FTSMC strategy is used to track the $d$ – $q$ -axis currents to obtain the proper $d$ – $q$ -axis voltages and improve the current dynamic performance. Then, the AESO method is utilized to observe the lumped disturbance and compensate for the input signal. Afterward, the FTSMC and AESO algorithms are combined to obtain the appropriate current and voltage signals in the $d$ – $q$ -axis. Finally, simulation and experimental results show that the proposed method not only achieves complete decoupling of the $d$ – $q$ -axis currents, but also has good performance in terms of dynamic response, steady-state accuracy, and robustness.

I. Introduction

Permanent magnet synchronous motors (PMSMs) based on field-oriented control (FOC) are widely used in many industrial applications due to their good torque performance, wide speed range, and fast dynamic response [1]–[4]. The FOC strategy achieves independent control of flux and torque by decomposing the stator current into excitation and torque components in a synchronous rotating coordinate system [5], [6]. However, the –-axis currents after the coordinate transformation have a cross-coupling phenomenon, which affects the dynamic performance of the system, especially at high frequencies or low carrier ratios [7], [8]. Moreover, the PMSM system will encounter different disturbances in practice, which may come from internal disturbances, such as friction and unmodeled dynamics, or from external disturbances, such as load disturbances. If these disturbances are not handled well, they will affect the performance of the system [9]–[11].