目前市售之電動手工具機，受限於體積限制需配合小型馬達，為達到高扭力輸出須加裝減速機，但減速機會有轉換效率問題。此外，考量到手工具機會直接影響到使用者，尤其是動力手工具所產生之振動或是噪音影響，容易造成使用者在作業上感到不適；且在一些精密科技，對於螺絲鎖付之工序中，會需要降低振動影響。有鑑於此，本研究提出直驅式電動手工具之馬達優化設計。

本論文旨在探討有限元素法應用於直驅式馬達設計，主要以雙氣隙結構為基礎建立出雛型機達，為減少雛型機之振動與噪音，採用轉子斜槽降低頓轉轉矩，最終新型機透過多重目標田口法趨勢設計做優化，以降低定子矽鋼片磁通密度、反電動勢諧波含量，及維持輸出平均轉矩能在目標值以上，以此完成新型機設計。

根據有限元素軟體Flux 2D與Flux Skew分析結果，新型機之電磁轉矩平均值為1.0571 N-m，相較於無槽馬達可提高16.6倍；而轉矩密度則為4.793 kN-m/m3，與參照組馬達相比可提升2.78倍；轉矩漣波部分新型機較參照組低了5.31%，由8.22%降低至2.91%；反電動勢總諧波失真方面，較參照組無槽馬達低了0.47%，由1.40%降低至0.93%。

Currently, the volume of electric screwdrivers sold on the market is limited by the small size of motors that they need to be matched with. Besides, traditional electric screwdrivers would add speed reducers to increase the torque, but adding them may cause transmission efficiency problems. Thus, the screwdrivers must consider the conversion efficiency of the reducer. Considering that the electric screwdrivers will directly affect the users, especially the noise and the vibration impact generated by the power tool, which is more likely to make users feel uncomfortable during the operation. In some precise technology, it is necessary to reduce the vibration in the screw locking process. Consequently, this research intends to propose "optimal design of direct-drive motors for electric hand-tools".

This thesis aims to explore the application of the finite element method in direct-drive motor design. The main model motor is built based on the double air gap structure. To reduce the vibration and the noise of the prototype, the rotor with skewed slots is applied to reduce the cogging torque more effectively. Finally, the new model is optimized by a multi-target field method trend design to reduce the magnetic flux density and back electromotive force harmonic content of the silicon steel sheet and maintain the output average torque above the target value, thus completing the direct drive motor design optimization.

According to the analysis of the finite element software, Flux 2D and Flux Skew, the average electromagnetic torque of the innovative archetype is 1.0571 Nm, which is 16.6 times higher than the slotless motor, and the torque density is 4.793 kN-m/m3. Compared with the control group, it can be improved by 2.78 times. On the other hand, the torque ripple of the new archetype is 5.31% lower than the reference group, from 8.22% to 2.91%. Besides, the total EMF harmonic distortion of the pattern is 0.93% lower than the comparison of 1.40%.

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