内置式U形永磁同步发电机转子结构优化

Rotor structure optimization of permanent magnet synchronous generator built-in type U

针对永磁同步发电机齿谐波含量大、电压畸变率高及存在齿槽转矩的问题,对内置式U形永磁同步发电机转子结构进行了优化.研究了齿槽转矩产生的原因,以6极72槽内置式U形永磁同步发电机为例,利用有限元方法分析磁极偏移程度及非均匀气隙程度对齿槽转矩及电压畸变率的影响.分析了圆形轴向转子通风道位置对永磁同步发电机性能的影响.结果表明:磁极偏移可以使齿槽转矩相位发生周期性变化,当磁极偏移0.5齿距时,所对应齿槽转矩最小,约为原来的25%;永磁同步发电机的齿谐波含量、电压畸变率及齿槽转矩随非均匀气隙程度的增加而降低;当转子通风道位置处于合适位置时,在去磁最严重的情况下,永磁体最小磁密面的磁密最大,说明适当的转子通风道位置可以降低永磁体的退磁风险;对于文中发电机,当转子通风道位置顺时针偏转2°机械角度时,永磁磁钢最小磁密面的磁密最大为0.331 7 T.

To solve the problems of tooth harmonic with high voltage distortion and cogging torque for permanent magnet synchronous generator(PMSG),the rotor structure of U type PMSG was optimized,and the cause of cogging torque was analyzed.Taking 6 pole PMSG with 72 slots as example,the effects of magnetic pole shift and non-uniform air gap on the electromagnetic properties of PMSG were analyzed by finite element method.The influence of the position of rotor axial cooling channel on PMSG performance was also studied.The results show that the magnetic pole shift can make the phase of cogging torque periodically change.When the magnetic pole offsets 0.5 tooth distance,the corresponding cogging torque is the smallest with about 25%of the original value.The tooth harmonic content,the voltage distortion rate and the cogging torque are decreased with the increasing of eccentricity of non-uniform air gap.When the position of rotor ventilation duct is suitable,the magnetic flux density in the magnet surface with maximum degaussing risk is biggest,which shows that the demagnetization risk of permanent magnets can be reduced by the appropriate rotor vents position.For the motor,the maximum magnetic density at the minimum magnetic density surface of permanent magnetic steel is 0.331 7 T when the rotor vents are shifted 2 degrees of mechanical angle.