Transverse flux machine

The laterally movable rotor core is located in the magnetic field of the fixed stator core. In the first picture a force acts to the right on the core, in the second a force to the left, in the third the core is in the middle of the pole and there is no lateral force.

The transverse flux machine ( TFM ) is an electrical machine that, in contrast to normal machines with diameter winding, has a circumferential winding that is arranged concentrically to the shaft of the machine. The magnetic flux runs transversely (perpendicular) to the plane of rotation.

Transverse flux machines are usually designed as permanent magnet synchronous machines, in single-phase or multi-phase construction. In principle, an asynchronous machine is also conceivable.

• With normal machines, the closed field line is visible when the machine is intersected in the xy plane of the Cartesian coordinate system or the r-φ plane of the polar coordinate system . It runs radially in the plane of rotation (r-φ plane), perpendicular to the axis of rotation.
• In contrast to this, the flow lines in the TFM run axially in the rz plane , parallel to the axis of rotation.

The advantages of this construction are:

• Decoupling of the magnetic and electrical circuit, independent dimensioning
• Elimination of the winding heads that do not contribute to torque generation
• This enables a much finer pole pitch: low speed with high torque, no gears.

The most serious disadvantages are the very complex mechanical construction and the high torque ripple.
The torque ripple can, however, be reduced by a suitable current control with a non-linear position-dependent characteristic.

Transverse Flux Reluctance Machine (TFRM)

The drawing on the right illustrates the principle of reluctance force used in the transverse flux reluctance machine ( TFRM ). With this type of machine, at least three phases are required to generate a defined torque. As with other machines, the three phases are alternately energized.

Linear section of a transverse flux machine.

The drawing on the right shows a transverse flux machine (TFPM) excited by permanent magnets. It is a linear section that can be lengthened and bent into a circle (no matter in which direction), like a round electrical machine . The iron is gray in the picture, the colors green and red mark the south and north poles of the magnets . In contrast to the TFRM (where you can simply think of a non-magnetic material instead of magnets) there is a force effect and a detent position that depends on the direction of the current.

Individual evidence

1. ^ Rolf Fischer: Electrical machines . 14th edition. Carl Hanser Verlag, Munich 2007, ISBN 978-3-446-41754-0 , pp. 351 ff . (updated and expanded edition).