An Improved Robust Model Predictive Speed Control with Inertia Identification for PMSM Drives in the Electrohydrostatic Actuator

Electrohydrostatic actuator (EHA), composed of permanent-magnet motors, is an integrated local hydraulic actuation system and has been utilized as the flight surface actuation in all/more electrical aircraft. The motor drives of the EHA require a strong antidisturbance performance and robustness owing to the 'variable speed/ variable load' conditions, which presents a challenge for the traditional field-oriented control. In this study, an improved robust model predictive speed control is put forward to enhance the load rejection performance and robustness. The characteristics of the aerodynamic load and the loads on the swash plate axial piston pump are first examined. Following the investigation of the discretization-related errors, the second-order modified discrete model based on the forward Euler (FE) and backward Euler (BE) methods both is presented. Based on the modified FE discrete model, a modified extended state observer (ESO) is presented to obtain a more accurate estimate of the disturbance during the transient state. Meanwhile, to lessen the effect of the mismatched inertia moment on the ESO, a modified moving horizon estimator based on the multiinstant BE discrete model is proposed. Finally, simulation and experiment results demonstrate the effectiveness, improved antidisturbance performance, and robustness by contrasting the proposed approach with the conventional model predictive speed control.