Optimization of bias current coefficient in the fault-tolerance of active magnetic bearings based on the redundant structure parameters

Abstract

To improve the reliability of magnetic bearings, the redundant structures are usually designed to provide the desired bearing characteristics continually by the reconfiguration of the remaining structures when some components fail. Bias current coefficient is one of the key coefficients in the fault-tolerant control (FTC) of magnetically levitated bearings, and its inappropriate value will result in the failure of providing the desired bearing force due to saturation constraints. This paper presents optimization approaches of the bias current coefficient based on the redundant structure parameters. By analysing the range of the bias current coefficient under saturation constraints mathematically, the existence of the optimal solution has been proved, and the model of the electromagnetic force (EMF), load current and the bias current coefficient has been established in this paper. In addition, algorithms to find the optimal solution has been designed for two kinds of optimization objectives, respectively, in FTC of magnetic bearings. Numerical verifications prove the effectiveness and the versatility of the proposed approaches in the different structures.

Keywords

• magnetic bearings
• bias current coefficient
• optimization
• fault-tolerance