Flux Yoke
Magnets are held in a housing for their full capability, while using a thin-wall housing will result in magnetic force leaking through the housing wall. That is where magnet yokes are used to prevent magnetic leakage thus maintaining the full capacity of the magnets.
- The value of a varies with the degree of magnetic leakage and the wall thickness of flux yoke, and so assume a = 1.08 to 1.12, since the difference in motor performance between with and without flux yoke is about 8 to 12%.