Inverse system decoupling control strategy of BLIM based on stator flux orientation

Abstract

BLIM, i.e. bearingless induction motor, is a multi-variable, nonlinear and strong coupling object. To achieve its dy- namic decoupling control with high performance, a novel dynamic decoupling control strategy is proposed. After analyzing the working principle and mathematical model of BLIM, the state equations based on stator flux orientation are established firstly. On the basis of reversibility analysis of BLIM system, the inverse system dynamic mathematical model based on sta- tor flux orientation is derived. And then, adopting inverse system method, the control system of BLIM is uncoupled to four linear subsystems, including: motor speed subsystem, stator flux-linkage subsystem, and two radial displacement components subsystems. System simulation results have shown that reliable dynamic decoupling control between relevant variables can be realized, higher static and dynamic control performance can be achieved; in particular, the influence of rotor parameters on the identification precision of motor magnetic flux-linkage can be avoided effectively. The proposed inverse system decoupling control strategy based on stator flux orientation is effective and feasible; a new way has been provided for high performance decoupling control of bearingless induction motor.