Volume 32 Issue 4 - June 1, 2020 PDF
Novel Motor Design Applications of Magnetic Material 3D Printing Techniques
Mi-Ching Tsai*, Electric Motor Technology Research Center
Department of Mechanical Engineering, National Cheng Kung University
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The development of electric machines (commonly known as motors) is moving towards precision and quality manufacturing. Motor designs are required to be robust, compact, and lightweight, and performance-wise, high efficiency, high power density, low vibration, and easy starting are musts. Traditional motor designs using 2D magnetic circuits have difficulties in minimizing motor volume; as such, this research combines new 3D deposition and magnetic material printing techniques and 3D magnetic circuit design to minimize volume and improve performance. These successes were achieved by amalgamating a biomimetic lattice structure, cooling flow channels, and a noise-dampening 3D resonance chamber into the 3D design to develop a biomimetic honeycomb structure with permanent magnet-free, low noise and low vibration rotor which became the first self-starting 3D printed motor design in the country. This research received grants from two three-year project intervals from the Ministry of Science and Technology totaling ~60M NTD, and domestically established a premier 3D printing motor design prototyping & manufacturing facility.
Figure 1. World’s first biomimetic honeycomb motor rotor structure featuring permanent magnet-free design, low noise and low vibration.

This design utilizes 3D magnetic material printing techniques in combining flow and magnetic field design to create an integrated fan & motor design (Figure 2). This allows the motor rotor to conduct magnetic fields as well as provide fan capabilities, thereby effectively increasing overall fan efficiency and power density as well as minimizing volume.

Figure 2. Integrated Fan Motor by 3D printing

Aside from soft magnetic material printing technology, this research also developed techniques for overcoming the high sensitivity of hard magnetic materials (permanent magnets) to oxidation as well as the complexities of alignment processes. Equipment for 3D printing permanent magnets was developed in-house with the capability of printing various 3D structures; surmounting the restrictions of traditional 2D magnetic material design (see Figure 3) and thus providing more flexibility in motor design.

Figure 3. Equipment for 3D printing permanent magnets

This research has developed key soft and hard magnetic deposition printing techniques as well as established a magnetic material prototyping service platform. By assisting industry, academia, and research organizations in rapid prototyping efforts, cross-industry assistance has been provided to engineering, medical, social sciences, and design colleges in NCKU. Over 100 companies have visited our 3D printing establishment during the past three years, and magnet, motor, and systems design companies have been in close cooperation with this establishment in an effort to vertically integrate the motor industry and create a research ecosystem, with this establishment acting as a platform for prototyping and development services.
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