Analytical optimization of the torque of a permanent-magnet coaxial synchronous coupling

This paper recalls the analytical formula of the tangential force between two permanent magnets and shows that this force does not vary linearly with the magnet depth. This formula is then applied to calculate the torque transmitted by a permanent magnet coaxial synchronous coupling. Such an analytical approach allows the analysis of the influence of various parameters characteristic of this coupling such as the number of pairs of poles, its mechanical airgap, the magnet-width and magnet-length, the mean radius of the airgap, and the angular shifting between the two rotors. These analytical expressions make an efficient optimization of the coupling structure in compliance with practical or economical constraints possible