Torque ripple investigation in coaxial magnetic gears

Abstract

Magnetic gears offer significant advantages such as low noise and vibration level, lower maintenance and higher reliability compared to mechanical gears and are suitable for many applications in the industry. The coaxial magnetic gear has been extensively discussed in the literature, since it achieves higher torque densities amongst other magnetic gear configurations. The magnetic field is generated by permanent magnets mounted on the two rotors and a modulator between them. The modulator consists of ferromagnetic segments that are typically encased in a resin in order to increase its stiffness without compromising the generated magnetic field. However, due to the development of radial forces, oscillations of the ferromagnetic segments occur, which lead to torque ripples that affect the operation of the coaxial magnetic gear drive in applications where accuracy is required. This work introduces a computationally lightweight analytical 2D model in order to determine the applied radial force on the ferromagnetic segments at each angle of rotation of the two rotors and henceforth calculate the displacement of these segments using FEA. In this way it is possible to assess the variation of the torque (ripple) versus the angle of rotation of the input or output shaft. A parametric investigation examining the influence of the ferromagnetic segment thickness on the resulting torque ripple of a specific drive was carried out illustrating the benefits of the analytical models developed herein.

Mathematical modeling of a magnetic gear for an autonomous wind turbine

“…However, despite the undeniable advantages provided by the use of gears in technical devices, they have a number of disadvantages, such as high noise level, low reliability, the need for lubrication, the need for regular technical inspec tions, unstable to sudden gusty winds, and low overload capac ity [18,19]. In addition, at wind speeds exceeding 12-14 m/s, special braking devices are required to protect the mechanical gearbox from failure [20,21].…”

Nonlinear control of coaxial double rotor magnetic gear based on high gain observer in wind turbine

“…In other words, in [12,13], try to increase the torque density capability of coaxial MGs by utilizing a Halbach rotor coaxial MG using artificial intelligence (AI). Moreover, the design of a permanent MG using the Halbach array in [14][15][16] was evaluated for reducing cogging torque and iron losses. Eventually, analyzing and testing the flux concentration of the coaxial magnetic gear (CMG) with Halbach rotors makeup is mentioned in [17,18].…”