Calculation and Analysis of an Integrated Motor-Magnetic Bearing Magnetic Circuit Model

The characteristic of high-speed magnetic levitation motors is that the rotor is relatively short to meet the requirements of rotor dynamics. Therefore, the internal layout of electromagnetic components in the system is more compact, and the distance between the magnetic bearing (MB) and the motor is closer. The magnetic field of the MB leaks into the motor through narrow air gaps, forming interference magnetic fields. This article focuses on analyzing the magnetic field crosstalk phenomenon in the high-speed magnetic levitation motor caused by the strict restrictions on the axial length of the rotor. An integrated magnetic equivalent circuit (MEC) model contains the MB and motor is proposed to calculate the magnetic flux density of the air gap and the degree of crosstalk. Based on the calculation results of the integrated MEC model and the axial length limit under rotor dynamics, a reasonable layout and position distribution are determined to reduce the degree of crosstalk. Through experiments, it is found that the maximum error in calculating the current stiffness of the MBs using the model proposed in the article is 9.43%, with relatively high consistency. Additionally, the amplitude of the MB suspension current decreases from 0.20A to 0.02A after layout optimization.