Extended state observer based current-constrained controller for a PMSM system in presence of disturbances: Design, analysis and experiments

Abstract

Considering overcurrent and total disturbances, i.e. measurement noise, parameter uncertainties, external load torque disturbance etc., a composite current-constrained control method based on non-cascade single-loop speed regulation control structure is adopted for permanent magnet synchronous motor system (PMSMs). First, a tracking state space model is proposed to transfer the matched and mismatched disturbances into a uniform matched disturbance. Second, a third-order extended state observer (ESO) is developed to satisfactorily attenuate the effect of the total disturbances with their estimation values via feedforward compensation, since a tracking differentiator (TD) is designed to arrange the transition process for the reference input signal to balance the contradiction between overshoot and quick response. Third, a composite ESO-based current-constrained controller with a penalty mechanism of q-axis current, constructed by a special nonlinear gain, is designed to deal with the overcurrent of the PMSMs speed regulation. In addition, a finite time bounded stability theory is introduced to analyze the proposed closed-loop speed regulation system. A bench mark experimental set-up based on NI CompactRIO 9045 and LabVIEW for a PMSMs is designed to verify and compare the performances of the proposed composite controller against conventional PID controller. Finally, the simulation and experiment results demonstrate the effectiveness and superiority of the proposed controller.