考虑机械气隙的无槽永磁直线电机热分析及改进（英文）

Thermal Analysis and Improvement of Slotless Tubular Permanent Magnet Linear Actuators Considering the Mechanical Air Gap

研究自然冷却的无槽管状永磁直线电机(tubular permanent magnet linear actuator,TPMLA)的机械气隙长度,通过约束和引导热量的流通路径来使永磁体的温度达到最低。通常无槽绕组产生的热量必须首先通过周围的空气进行传导,其散热条件比有槽电机更加恶劣。虽然较小的机械气隙可以增强气隙磁密,但是绕组产生的大部分热量将会传到永磁体上,导致永磁体温升,并减小其剩磁,使永磁体有失磁风险。因此,合理的机械气隙长度对于无槽管状永磁直线电机极其重要。建立电机的电磁和热模型,并将结果与有限元方法进行比较。制作3台不同机械气隙的样机,并进行实验。结果表明,机械气隙对限制和引导热流具有重要的作用,通过增加机械气隙长度来降低永磁体温度的方法取得了良好的效果。

In this paper,the mechanical air gap of a natural air-cooled slotless tubular permanent magnet(PM)linear actuator(TPMLA)was investigated,trying to constrain and direct the heat flow in well-defined paths and minimize the PM temperature.Generally,the heat generated by slotless windings must pass through the surrounding air first.For this reason,the heat dissipation condition is much worse than slotted machines.Although a small mechanical air-gap length tends to increase the air-gap flux density,it makes a large portion of heat generated by windings being transferred to the PM side,heating the PM and lowering the remnant flux density of PM.Therefore,a proper mechanical air gap is of great importance for PM temperature of slotless TPMLA.Electromagnetic and thermal models were established,and were compared with finite element models.Three prototypes of slotless TPMLAs having different mechanical air-gap lengths were built and tested.The effect of mechanical air gap on constraining and directing the heat flow is greatly prominent,which shows that the attempt to minimize PM temperature of TPMLA by increasing its mechanical air-gap length properly is highly effective.