Demagnetization test and research on thermal stability of Sm2Co17 permanent magnets for motors
摘要
针对永磁材料在工况条件下的失磁问题,研究钐钴(Sm2Co17)永磁体在高温、振动、冷热冲击及高温耦合退磁场下的磁性能老化规律.在200℃时,该Sm2Co17永磁体的性能为:Br=1.048 T,Hcb=781.6 kA/m,Hcj=1 465.0 kA/m,(BH)max=207.7 kJ/m3,且退磁曲线(B曲线)未出现拐点.当磁导系数Pc=2.16时在200℃老化处理后磁通损失仅为0.40%,表明该永磁体可在200℃稳定工作.在冷热冲击和振动条件下,磁通损失分别小于0.75%和0.41%,验证了永磁体在冷热冲击和振动下的稳定性.在高温或高温与退磁场的耦合条件下,最初6 h内不可逆退磁较明显,之后磁通损失基本稳定.因此,为了确保永磁体的稳定性,可以根据电机的工作温度对永磁体做预稳磁处理,满足电机复杂工况对永磁体的高稳定性要求.
To address the demagnetization issues of permanent magnet materials under operational conditions,this paper investi-gates the magnetic property aging law of samarium-cobalt(Sm2Co17)magnets under high temperature,vibration,thermal shock,and high-temperature coupled demagnetizing fields.The Sm2Co17 magnets exhibit the following properties at 200℃:Br=1.048 T,Hcb=781.6 kA/m,Hcj=1 465.0 kA/m,and(BH)max=207.7 kJ/m3,and their demagnetization curves(B curves)show no knee point.After aging treatment at 200℃with Pc=2.16,the flux loss was only 0.4%,confirming the Sm2Co17 magnet's stable performance at 200℃.Under thermal shock and vibration conditions,the flux loss was less than 0.75%and 0.41%respectively,verifying the magnet's stability under thermal shock and vibration.Under high temperature or coupled high temperature and demagnetizing field conditions,significant irreversible demagne-tization occurred during the initial 6 hours,after which the flux loss stabilized.Therefore,to ensure the stability of permanent magnets,pre-stabilization magnetization treatment can be performed based on motor operating temperatures to meet the high stability require-ments for permanent magnets in complex motor conditions.
