Anti-Saturation Speed Regulation Using Dual-Parameter Sliding Mode Observer for PMSM Servo Systems

Accurate state estimation is essential for designing high-performance permanent magnet synchronous motor servo systems. However, the saturation of system input will severely undermine the consistency between control commands and actual inputs, leading to deviations between observer’s state prediction and actual system state, further deteriorating control performance. To address these issues, this article presents an anti-saturation speed regulation scheme integrating a dual-parameter sliding mode observer (DPSMO) and a variable-structure sliding mode controller (VSSMC). The DPSMO is used to synchronously identify system inertia and lumped disturbance under the saturation conditions, where three saturation update conditions are constructed to determine in real time whether the estimation of system inertia should be updated. Meanwhile, an auxiliary term of the VSSMC is designed to enforce system input constraints, thereby mitigating the impact of input saturation on system control performance. Moreover, a novel reaching law considering terminal attractor and hyperbolic tangent function is proposed to enhance convergence speed and reduce sliding mode chattering, without the need to determine the disturbance upper bound. Simulation and experimental results demonstrate the effectiveness of the proposed scheme.