为了提高盘式微电机的电磁转矩,针对气隙磁通密度和电枢电流强度两个方面,对转矩特性、磁场分布和对流散热等影响因素进行研究.根据安培力的产生原理,推导了平面定子绕组在轴向磁场中的电磁转矩公式;对永磁体产生的气隙磁场进行了三维数值计算和实际测量,给出提高工作磁通密度的重要因素;根据基于热–流耦合的空气对流散热机理,分析并实测了温度场分布规律,提出利于对流的主动散热结构.研究结果表明:气隙厚度对磁通密度影响显著,由1.5 mm减小到1.0 mm,转矩常数增加22.6%;而磁体厚度的增加具有饱和特性.对流通道的建立大大加强了发热的耗散,改进后电流强度可提高 52%.所设计的微电机性能良好,具有较高的实用价值,对其研究的计算分析方法精度较高,具有推广的潜力.
To improve the electromagnetic torque of disc-type micromotor, the effects of torque characteristics, magnetic field distribution, and thermal convection on air-gap flux density and armature current intensity were investigated. According to the Ampere's law, the electromagnetic torque formula for the plane electronic winding in the axial flux of magnetic field was derived. Three-dimensional (3D) numerical calculation and actual measurement were carried out on the air-gap magnetic field produced by the permanent magnets, and the most important factor for increasing the magnetic flux density was found out. According to the air convection heat transfer mechanism based on thermal-fluid coupling, the temperature field distribution law was analyzed and measured, and an active cooling structure being conductive to convection was proposed. The study results show that the air-gap thickness has a significant effect on magnetic flux density, the torque constant increases 22.6% when the air-gap thickness decreases from 1.5mm to 1.0mm, while the magnet thickness has a saturation characteristic. Establishing the convection channel helps dissipation of Joule heat, and increases the current intensity by 52%. The designed micromotor owns good performance and high practical value. The proposed calculating and analyzing method has a high precision and the potential for popularization.