# Multi-Step Design Optimization for the Improvement of an Outer-Rotor Brushless Direct Current Motor
## 5 Conclusions  
The conclusion to this study on BLDC motors emphasizes the significant improvements achieved in these motors for various electrical applications. There has been a consistent annual increase in research and development focused on BLDC motor design. Most researchers in motor design have identified the superior efficiency of BLDC motors compared to traditional motors. BLDC motors are noted for consuming less electrical power than conventional motors. Their design is characterized by compactness, a small size, ease of control, being energy-saving, and being lightweight. The conclusion underscores the necessity of further analyzing and improving the design of the BLDC motor to enhance its performance characteristics. The research utilized the Taguchi Method and RSM in conjunction with FEM analysis for optimizing the motor's design. The Taguchi Method initially identified the optimization points of design parameters using a reference model of an actual 26-watt BLDC electric fan motor. RSM was then employed for two-step optimization in the FEM analysis--the investigation aimed to improve structural performances in output power, torque, and efficiency. After the first step of optimization, the efficiency was 12% higher than that of the reference design, and this was further improved by 3% in the second step of optimization. Therefore, the final proposed model achieved an energy efficiency that was 15% higher than the reference design. The output power of the proposed model was also 10 Watts higher than the reference design. The study found a reduction in losses and an increase in the maximum torque by 0.032 Nm in the proposed design. The design simulation results were produced and studied using JMAG software for FEM analysis. The evaluation compared the reference model's design with the proposed design using three different methods of motor design optimization. This comparison showed that the proposed design exhibits improvements in terms of the performance of the motor design. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Performance** & **Reference** & \multicolumn{2}{c}{**Proposed (Optimized)**} \\  & & **Taguchi Method** & **Taguchi-Based RSM** \\ \hline Efficiency (\%) & 72.76 & 81.93 & 83.65 \\ Output Power (W) & 26.06 & 31.46 & 30 \\ Torque (Nm) & 0.098 & 0.1020 & 0.1039 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: The reference model was compared with the Taguchi method and the Taguchi-based RSM. **Author Contributions:** Conceptualization, C.-Y.H. ; methodology, C.-Y.H. and S.M.H. ; software S.M.H. ; validation, C.-Y.H. and S.M.H. ; formal analysis, C.-Y.H. and S.M.H. ; investigation, C.-Y.H. and S.M.H. ; resources, C.-Y.H. and S.M.H. ; data curation,S.M.H. ; writing--original draft preparation, C.-Y.H. and S.M.H. ; writing--review and editing, C.-Y.H. and S.M.H. ; visualization, C.-Y.H. ; supervision, C.-Y.H. ; project administration, C.-Y.H. and S.M.H. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was fully funded by the NSTC 111-2221-E-036-010-MY2 project for the National Science and Technology Council (NSTC) in R.O.C (Taiwan), and Tatung University. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** This article contains real data results from the reference motor supported by Lutron Industrial Co., Ltd., as well as another part of the data generated to support the findings of the present study. **Acknowledgments:** The authors gratefully acknowledge full funding support from the NSTC 111-2221-E-036-010-MY2 project for the National Science and Technology Council (NSTC) in R.O.C (Taiwan), Professional Equipment Support from Energy Administration, Ministry of Economic Affairs, R.O.C (Taiwan) and Taiwan Green Productivity Foundation and Tatung University. The authors would like to acknowledge the technological support from Jotactic Automotive Consulting Co., Ltd. and the Editor-in-Chief, Editor, and Reviewers for their valuable reviews.