Axial Flux Motor

Motors and generators with MagNet

An axial flux motor is different from conventional electric motors due to the different path of the magnetic flux. In conventional motors the flux flows radially through the air gap between the rotor and the stator. However in this motor the flux flows parallel to the axle of the motor. This type of rotor is often referred to as a pancake rotor and can be made much thinner and lighter than other types. When quick changes in speed are required, axial flux motors are an ideal choice.

This particular 4-pole disc wave winding is taken from M.G.Say & E.O.Taylor book Direct Current Machines. It was simulated using MagNet 2D/3D.

Axial flux motor created in MagNet 2D/3D

METHODS and RESULTS

SINGLE SEGMENT OF WINDING

Connecting the 21 segments to form the complete winding is made much easier due to MagNet's capability to automatically determine the conducting path between coil terminals. For simulation purposes, all the windings segments in this motor are treated collectively as just one coil component defined by two terminals, one on the end of each brush.

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CURRENT DENSITY MAGNITUDE IN THE AXIAL MOTOR

changing current density in the axial flux motor

This animation of the changing current density magnitude demonstrates the automatic commutating action of the brushes. MagNet simulates the conductor at each position of the rotor to determine where the current will flow. Note how the current density is higher at the corners due to the fact that in this motor the rotor conductors are made from solid copper rather than stranded wires.

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DETERMINING THE OPTIMAL OPERATION OF THE MOTOR

The size and location of the brushes and sectors is critical to optimal operation of the motor. This animation shows when each coil switches off in the gap between magnet poles before the current direction reverses. The timing of this motor could be improved to maintain a uniform current density over the cycle.

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PATH OF THE CURRENT AROUND THE ROTOR

The current follows through a very convoluted path while making its way around the rotor as shown in this animation.

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