The modulator cage (top right), end caps, and support structures were 3D printed in PETG, while the high-speed, low-speed, and modulator rotors (top left) were machined out of a soft magnetic composite called Somaloy. The shafts were made of non magnetic 300 series stainless steel. The mechanical design is shown in the middle picture and the fully assembled prototype is shown at the bottom.

Transverse Flux Magnetic Gear (TFMG)

Project Overview

Project statement:

  • Design and optimize a new configuration of magnetic gear that minimizes the use of permanent magnets (PMs) since assembling rotors with dozens of small magnets is difficult and the price volatility of PMs can be quite high

Main objectives:

  • Create a detailed electromagnetic FEA model in Ansys Maxwell to perform design optimization and performance simulations

  • Develop the mechanical design of the magnetic gear

  • 3D print parts where possible and create drawings for other parts for machining

  • Iterate on the mechanical design

  • Characterize the performance via dynamometer tests

Challenges:

  • The one large magnet produced a huge axial force making the mechanical design difficult

  • Safely attaching the magnet to the rotor

  • Making sure the rotors did not rub with the modulators (1mm air gap)

  • Measurements experienced a lot of noise

Results:

  • FEA model was successfully developed (and later validated via prototype results)

  • Design features like the shape and size of the modulators and rotor disks was optimized

  • Over many iterations the mechanical design was implemented

  • Dynamometer tests were run

  • Volumetric torque density of 6.5 kNm/m^3

  • Slip torque was determined to be 1.71 Nm

  • Peak efficiency was determined to be 83%

Although the aforementioned slip torque, torque density and efficiency are far from groundbreaking numbers, this new topology excels in the fact that it is much simpler to manufacture and utilizes one PM. For applications where the manufacturing cost is critical, this topology could be used. Additionally, the design of this topology would allow for the PM disk to be magnetized after assembly by using dual phase materials which would further simplify assembly.

A much more detailed explanation and analysis can be found in my research paper on this topology. The paper can be accessed via IEEE Xplore or directly.

Testing setup (left) and different efficiencies for different load conditions (right)