Design and analysis on uniformity of magnetic flux density in Lorentz force-type magnetic bearing

With universal deflection, the high-speed rotor of new magnetically suspended control & sensitive gyroscope (MSCSG) can output high-accuracy and high-bandwidth deflection control torque, which can inhibit periodic vibration of the space-based platform. MSCSG is fully actively controlled in 5 degrees of freedom degrees of freedom (DOF) and its deflection control in 2 radial DOF is realized by Lorentz force-type magnetic bearing (LFMB). Based on basic structure of LFMB, the mathematical model of electromagnetic force and electromagnetic torque were set up and analysis shows that the uniformity of air gap flux density is the main factor that affects output torque accuracy and measuring accuracy of angle rate. The optimized design of LFMB with 1J50 thin slice added to the surface of inside and outside permanent magnet was introduced and the air gap flux density was analyzed to be highly uniform by finite element simulation. The output torque is more accurate and control accuracy is higher. The permanent magnet can support larger magnetic area with a trapezoid cross section to enlarge the air gap flux density and reduce power consumption. Besides, it can remain stable when the rotor is highly rotating. Some useful references can be provided by this paper for the design and analysis of magnetically suspended rotor gyroscope with deflection characteristic.