Excitation coil manufacturing technology for high temperature active magnetic bearing

In view of many defects and deficiencies of high temperature excitation coil at home and abroad,a new type of maze like excitation coil structure was proposed.Firstly,the monolayer maze like coil was manufactured by electric discharge machining (EDM) wire cutting,and the high temperature resistant insulating material was put into the gap of coils sufficiently and uniformly.Secondly,the vacuum soldering process was utilized to connect each layer.Finally,the packaged coils were used in a single degree-of-freedom (DOF) high temperature active magnetic bearings (HTAMB) test,and the HTAMB can achieve stable levitation for 20 hours at 550℃.The results show that the welding line resistance value is small,the shear strength of the selected solder and welding line shaped by copper parent metal are credible and coil insulation performance between turns and layers is fine in high temperature environment.Therefore,the high temperature excitation coil is feasible in theory and technology.The oxidized and impaired excitation coil internal structure caused by high temperature levitation test shows that the high temperature resistant insulating material used in encapsulated coil has certain flaws,and they need further research.