Significant increase in torque and power density
This combination of high slot fill factor, excellent thermal characteristics and limited current displacement losses can now be used in many ways in machine design. A significant increase in torque and power density can be achieved when cast inductors are used in a similar construction space. Alternatively, the same torque level can be maintained while the construction space and weight could be reduced.
The increase in the slot fill factor also allows aluminium to be used as conductor material. The disadvantage of aluminium when it comes to its electrical conductibility is offset by the higher fill factor, while the coil weight can be reduced by 50 percent and the raw material costs by 85 percent.
Further application potential is there to be taken advantage of with respect to the geometric design freedoms when developing innovative cooling concepts. It is in this way that the build-up of thermal hotspots can be avoided in areas that are subject to high increases in temperature (e.g. on the coil head) through the targeted increase on the cross-section of the conductor.
Thanks to the different casting options available, the inductors can be manufactured in various sizes and in any batch numbers required. When precision casting is employed, conductor heights of less than a tenth of a millimetre at inductor lengths of between 10mm and 200mm can be realised, while inductors destined for installation in large machines, produced using the Lost-Foam process, can be as much as one metre long. For very large batch numbers, the production of the inductors in permanent moulds using high-pressure casting or low-pressure casting results in surprisingly low costs per individual product manufactured.
The selection of the correct casting process depends on the specific application under consideration of the batch sizes being aimed for and the quality demands which this entails. A tailor-made insulation coating is then applied. The optimisation goals in this case, in addition to ensuring the insulation strength when minimising coat thickness, are increasing the temperature resistance as well as avoiding the indications of attrition due to partial discharges.
In order to make it possible to create prototypes quickly, a complete process chain is available at Fraunhofer IFAM, which can make it possible to manufacture coated inductor geometry as hardware within just a few days.