A Robust High-Order Disturbance Observer Design for SDRE-Based Suboptimal Speed Controller of Interior PMSM Drives

Muhammad Saad Rafaq,Anh Tuan Nguyen,Han Ho Choi,Jin-Woo Jung

doi:10.1109/access.2019.2953073

Abstract

This paper proposes a robust high-order disturbance observer (HODO) for the state-dependent Riccati equation (SDRE)-based suboptimal speed controller of an interior permanent magnet synchronous motor (IPMSM) drive. The conventional disturbance observers (DOs) cannot accurately estimate the fast time-varying disturbances of an IPMSM during the transient-state because the disturbances are assumed to change slowly, so the inaccurately estimated disturbances lead to conservative robust control. Unlike the conventional DOs, the proposed HODO guarantees the fast convergence of the estimated error for an IPMSM drive by accurately estimating the fast time-varying disturbances and their all high-order derivatives. Also, it is specifically applicable to the SDRE based suboptimal speed controller which cannot completely eliminate the steady-state error in the presence of mismatched disturbances and uncertainties. Finally, the simulation results via a MATLAB/Simulink package and the experimental results via a prototype IPMSM test-bed having TI TMS320F28335 DSP are presented to verify the faster dynamic response, smaller steady-state error, and more robust response of the SDRE speed controller with the proposed HODO compared with the conventional 1st-order DO, conventional generalized proportional integral observer (GPIO), and conventional SDRE observer.

Highlights

For the past few decades, electric vehicles (EVs), spindle drives, robotics, and air-conditioners have encouraged the researchers to work on interior permanent magnet synchronous motor (IPMSM) drives with attractive characteristics such as high torque density, compact size, wide speed range operation, and robust rotor structure [1]
In order to accurately estimate the fast time-varying disturbances, this paper presents a high-order disturbance observer (HODO) design that can be utilized in most speed control techniques of an IPMSM drive for the disturbance compensation
It is noted that the order of the proposed HODO is fixed during the online testing which is selected in Section IV.B for the IPMSM drives based on the faster convergence rate, accurate disturbance estimation, and reduced computational burden

Summary

INTRODUCTION

For the past few decades, electric vehicles (EVs), spindle drives, robotics, and air-conditioners have encouraged the researchers to work on interior permanent magnet synchronous motor (IPMSM) drives with attractive characteristics such as high torque density, compact size, wide speed range operation, and robust rotor structure [1]. During the transient-state, the disturbances associated with the fast electrical dynamics change quickly [26], so the conventional DOs do not accurately estimate the fast time-varying disturbances, which result in the conservative robustness to the speed control of an IPMSM. In order to accurately estimate the fast time-varying disturbances, this paper presents a high-order disturbance observer (HODO) design that can be utilized in most speed control techniques of an IPMSM drive for the disturbance compensation. In order to highlight the faster dynamic response, smaller steady-state error (SSE), and more robust response of the proposed technique, the comparative experimental performance evaluation of the state-dependent Riccati equation (SDRE) speed controller [7] with the proposed HODO, the conventional the 1st-order DO [20], the conventional GPIO [27], and the conventional SDRE observer [7] is carried out through a MATLAB/Simulink package and a prototype IPMSM testbed with TI TMS320F28335 DSP

DYNAMIC MODEL OF AN IPMSM WITH UNCERTAINTIES

HIGH-ORDER DISTURBANCE OBSERVER DESIGN

VALIDATION AND IMPLEMENTATION UNDER DIFFERENT OPERATING SCENARIOS

Findings

CONCLUSION