Motor Design Issues
One of the issues motors can deal with is magnetic saturation of the core. Due to the material properties of the core laminations, a limited amount of magnetic flux can be built up in the core.
Even more important in many cases than core saturation, is the heat produced by resistance in motor windings, and the eddy currents in the motor core itself. The reason heat is an issue for these motors specifically, is the use of high strength rare earth magnets which are sensitive to extended heat exposure despite having a curie point of 340-350 C. For large drone motors, the casing is built with large openings to allow forced air cooling from the props. To combat this issue, high end motors come with premium high temperature magnets, which allow the motor to be run harder before damage occurs. One of the solutions to improving core electrical properties is to build them using a Chemical Vapor Deposition (CVD) process such as is done here.
This process results in a core with much lower DC relative permittivity for similar magnetic saturation levels. This means that since the core conducts less induced current, less energy is wasted as heat.
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