Brushless DC motor torque

QuickField simulation example

A brushless DC motor with permanent magnets and three phase coil excitation.

Problem Type
Plane-parallel problem of DC magnetics.

Geometry

Axial length of the motor is 40 mm.

Given
The four magnets are made of Samarium-Cobalt with relative permeability of 1.154 and coercive force of 550 kA/m.

The current densities for the coil slots are as follows:
phase A: 1.3 A/mm²,
phase B: -1.3 A/mm²,
phase C: 0 A/mm²

The inner and outer frames are made of Cobalt-Nickel-Copper-Iron alloy.
The B-H curve for the Cobalt-Nickel-Copper-Iron alloy:

The B-H curve for the steel:

Task
Calculate the torque as a function of rotor position.

Results
The maximal torque is 0.094 N*m.

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