According to the GKN Sinter Metals, using SMCs can make motors with smaller dimensions, lower weight and reduced noise.
The motor consists of a stator element, a copper winding and a rotor with permanent magnet, with the stators made of SMC material consisting of pure iron particles with diameters of less than 0.2 millimeters coated with an insulation layer. There are three versions of SMC material, and the properties of the powder and the insulation layer allow specific control of permeability and losses. The three-dimensional stator design approach is free, particularly in axial direction.
When pressed to the desired shape, the material is cured at temperatures between 600 – 700°C, much lower than the 1000°C commonly used in sintering, so as to not cause damage to the insulation layer. This layer allows three-dimensional magnetic properties which can reduce eddy current losses. Another benefit provided is the reduction of the copper content, reducing weight and cost when compared to traditional radial flux motors. The copper winding along with two identical stator poles in combination with a permanent magnet in the rotor generate a greater torque density. In order to produce a motor with an output of one kilowatt, three phase elements have to be assembled in line with a displacement of 120 degrees each. Higher performance can be achieved with a modular design of several motors assembled in line. Their frequencies range from 500 Hz up to 30 kHz.
A transversal flux motor when compared to a radial flux motor has a more compact design with as much as 30% reduction in size. GKN says. With only small masses rotating in the rotor supported by axial magnetic forces, the motor also has decreased noise.
The development of the transversal flux motor coincides with the growing demand for high-performance electric motors of compact design and low weight. The development of the motor is a result of a collaboration between GKN and RWTH University of Aachen.
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