Magnetic gear transmissions are promising alternatives to mechanical ones due to their contactless power transfer, reduced acoustic noise and vibration, inherent overload protection, and improved reliability. However, their design requires fast but accurate tools. While three-dimensional finite-element models offer good accuracy, their complexity hinders their use for design purposes. Two-dimensional representations, on the other hand, tend to overestimate performance due to the lack of end effects in the axial direction. This paper proposes a hybrid design and optimization framework for coaxial magnetic gears that couples a two-dimensional optimizer based on a genetic algorithm with a three-dimensional parametric model. The former model helps identify promising combinations in the design variable space. Then, specific selections are refined through the three-dimensional model. Numerical results show that both approaches exhibit consistent parameter trends, with a resulting prototype yielding a torque density of 213 Nm/L in an envelope contained within 90 mm of diameter and 16.57 mm of active length.

Active suspension systems are gaining growing attention in the automotive industry. This trend aligns with vehicle electrification and X-by-wire technologies adoption, also answering to the increasingly stringent requirements for passenger comfort and safety. Among the possible solutions, electromechanical actuators represent a valid alternative to traditional shock absorbers, integrating an electric machine that can be easily controlled to deliver the desired forces in both active and passive operations. The present work aims at developing an innovative transmission compound for a rotary electromagnetic active suspension system that is able to obtain high level NVH and safety performances. Two different proposed systems are analyzed. The first one couples a cycloidal transmission stage to a polymeric planetary one, while the second one couples the same cycloidal stage to a concentric magnetic gearbox. Both of them are expected to improve the NVH performances of the shock absorber, thanks to the high efficiency of the cycloidal reducer and to the properties of plastic materials and of magnetic coupling. The proposed systems are analyzed analytically and in simulation environment, providing promising results in terms of efficiency and torque density.