The article does say: > Furthermore, by using discrete rectangular coils inset into the stator poles, the HET needs 30% less copper than a motor of similar siz

The article does say: > Furthermore, by using discrete rectangular coils inset into the stator poles, the HET needs 30% less copper than a motor of similar size. The design also eliminates end windings – lengths of copper that lie outside the stator in a typical motor, generating wasted magnetic field and heat. So it sounds like less heat is part of the secret sauce.