Analytical calculation of the torque produced by transverse flux machines

Abstract

An analytical technique for the calculation of torque produced by a transverse flux machine is developed in this paper. In this technique, the magnets are replaced by their equivalent current sheets and the torque is calculated using the Lorentz force equation. The flux density distribution is calculated using a conformal mapping method that takes into account curvature and slotting. The result is a relatively simple equation that relates torque to the electric and magnetic loadings of the machine and a flux factor that depends on key machine geometrical parameters. The results of the analytical model are verified using finite element analysis and experimental data.

A Review of Transverse Flux Machines Topologies and Design

“…Another method consists of replacing PMs with their equivalent currents, introducing a flux factor to account for the flux that does not produce torque. This approach uses a complex permeance method to calculate the magnetic flux and the flux factor is calculated through the Schwarz-Christoffel conformal mapping [78]. After that, back-EMF can be estimated by conservation of energy [78] or more precisely calculated using a virtual mutual inductance approach [79].…”

“…This approach uses a complex permeance method to calculate the magnetic flux and the flux factor is calculated through the Schwarz-Christoffel conformal mapping [78]. After that, back-EMF can be estimated by conservation of energy [78] or more precisely calculated using a virtual mutual inductance approach [79]. The proportional-logarithmic transformation maps the cylindrical domain into a rectangular one.…”

“…In this case, the machi is directly attached to the wind turbine, whereas the stator is connected to the grid though a full-scale power converter. In order to deliver a high power from very low rotational speeds, in the range of 5 to 25 rpm [23,78,79], a high-torque generator is required: this is where TFMs emerge as strong candidates to replace conventional radialflux PM synchronous machines (PMSMs). TF generators from 180 W [66] to 50 kW [71] have been found in the literature.…”

“…PMs length has a significant effect on the machine performance, but the number of poles is predominant [23]. Besides, if PMs are axially longer than the stator cores, the fringing flux in the axial direction produces torque [63,78,80].…”

Analysis of power factor in variable flux reluctance machines with MMF‐permeance model

“…However, due to the limit of FEA, the underlying mechanism of the revealed conclusions are still shaded. In [20] and [27], a magnetic equivalent circuit based and a subdomain based analytical methods are proposed for power factor calculation. However, these methods are actually alternative ways of FEA for airgap magnetic field calculation, whereas they fail to explain the relationship between the individual design parameters and the power factor, as well as the nature of low power factor issue.…”