Because of the difficulty in fabricating iron-core solenoid coils by micro electro-mechanical system (MEMS) processes, existing micromotors typically have an axial-flux structure with planar spiral coils or air-core solenoid coils. However, solenoid iron-core microcoils have a higher inductance and a lower magnetic resistivity than spiral coils and air-core solenoid coils. In this study, a radial-flux permanent magnet (PM) micromotor with 3D iron-core MEMS in-chip coils of high aspect ratio was designed and fabricated. The three-phase PM brushless direct current (BLDC) micromotor has four Nd-Fe-B magnet poles on a steel rotor and six solenoid Cu coils of high aspect ratio (coil height/line width = 14) in the silicon stator fabricated using MEMS processes. Iron cores were inserted into the coils, and a low-resistivity magnetic circuit was established. At 100 Hz, the inductance of a 15-turn coil was $13.2\mu \text{H}$ . The coils were embedded tightly in the silicon substrate, resulting in a good heat dissipation performance and thus a high current-carrying capacity. The hexagonal sheet-type micromotor weighed 2.25 g with a volume of 586.5 mm3 before bearing packaging. The modeling results showed that at 10000 rpm, the torque was $676\mu \text{N}\cdot \text{m}$ and the power density was 314 W/kg. This micromotor incorporates a conventional large-scale BLDC motor structure and the proposed design will help improve the power density and efficiency of micromotors, thereby broadening their application prospects.

中文翻译：

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具有高纵横比 3D 电磁铁芯 MEMS 片内线圈的径向磁通永磁微电机

由于微机电系统(MEMS)工艺难以制造铁芯螺线管线圈，现有的微电机通常具有带有平面螺旋线圈或空心螺线管线圈的轴向磁通结构。然而，螺线管铁芯微线圈比螺旋线圈和空芯螺线管线圈具有更高的电感和更低的磁阻率。在这项研究中，设计并制造了具有高纵横比 3D 铁芯 MEMS 片内线圈的径向磁通永磁 (PM) 微型电机。三相永磁无刷直流 (BLDC) 微电机在钢转子上具有四个 Nd-Fe-B 磁极，在使用 MEMS 制造的硅定子中具有六个高纵横比（线圈高度/线宽 = 14）的螺线管铜线圈过程。铁芯插入线圈，并建立了低阻磁路。在 100 Hz 时，15 匝线圈的电感为 $13.2\mu\text{H}$。线圈紧密嵌入在硅基板中，具有良好的散热性能，从而具有较高的载流能力。轴承包装前，六角片状微型电机的重量为2.25 g，体积为586.5 mm3。建模结果表明，在 10000 rpm 时，扭矩为 $676\mu \text{N}\cdot \text{m}$，功率密度为 314 W/kg。该微电机采用了传统的大型无刷直流电机结构，所提出的设计将有助于提高微电机的功率密度和效率，从而拓宽其应用前景。从而具有良好的散热性能，从而具有较高的载流能力。轴承包装前六边形片状微型电机的重量为2.25 g，体积为586.5 mm3。建模结果表明，在 10000 rpm 时，扭矩为 $676\mu \text{N}\cdot \text{m}$，功率密度为 314 W/kg。该微电机采用了传统的大型无刷直流电机结构，所提出的设计将有助于提高微电机的功率密度和效率，从而拓宽其应用前景。从而具有良好的散热性能，从而具有较高的载流能力。轴承包装前六边形片状微型电机的重量为2.25 g，体积为586.5 mm3。建模结果表明，在 10000 rpm 时，扭矩为 $676\mu \text{N}\cdot \text{m}$，功率密度为 314 W/kg。该微电机采用了传统的大型无刷直流电机结构，所提出的设计将有助于提高微电机的功率密度和效率，从而拓宽其应用前景。扭矩为 $676\mu\text{N}\cdot\text{m}$，功率密度为 314 W/kg。该微电机采用了传统的大型无刷直流电机结构，所提出的设计将有助于提高微电机的功率密度和效率，从而拓宽其应用前景。扭矩为 $676\mu\text{N}\cdot\text{m}$，功率密度为 314 W/kg。该微电机采用了传统的大型无刷直流电机结构，所提出的设计将有助于提高微电机的功率密度和效率，从而拓宽其应用前景。