Analysis of Surface Interlaminar Fault Detection Method for Radial Magnetic Bearing Rotor Cores

This article proposes a novel detection method for diagnosing the surface interlaminar short-circuit fault (SILSCF) on radial magnetic bearing (MB) rotors. The method is specifically designed for the particular structure of MBs and provides a simplified operation procedure compared to existing methods. Since SILSCF is primarily caused by issues in the processing of the iron core, our study begins by examining the manufacturing processes of radial MB rotors and analyzing the impact of SILSCF on bearing performance. Subsequently, a detection device that utilizes the eddy current effect on the rotor surface is proposed. By employing a custom U-shaped tooling, the insulation condition of the rotor surface can be converted into distinct inductance signals. An analytical model is developed to analyze the inductance characteristics of the proposed device. After that, four prototypes of the investigated radial MB with typical SILSCFs are manufactured. Together with the validation of the analytical calculations, the most suitable test frequencies are selected and a standardized detection procedure is proposed. The final experiments demonstrate that the various degrees of SILSCFs in radial MB rotor cores can be detected with sufficient accuracy using the proposed detection device and method.