Flux Control Characteristic of Open and Closed FOC

The authors succeeded in controlling the flux in ferrite orthogonal cores (FOC) by raising them out of or lowering them into a magnetic fluid. Several differences between open and closed FOCs were observed: 1) when submerged, open type FOCs and the magnetic fluid form a serial magnetic circuit, while the closed type forms a parallel magnetic circuit; 2) the main magnetic flux in the core of open FOCs can be controlled directly, while the closed type controls only leakage flux; 3) the flux can be controlled in both body and legs of the open type, but only in the legs of the closed type; and 4) the open type is more sensitive to such control.