Forces in Nonlinear Magnetic Circuits

The equations for force and torque which have been derived in the foregoing pages are based largely on the concept of inductance, and therefore apply strictly only to magnetic circuits that are linear. However, they may yield values that are good approximations for nonlinear magnetic circuits that are not highly saturated. Graphical analysis may be used to yield more accurate results and more valid relationships than those that make use of inductance. To keep the discussion simple, we shall consider only magnetic circuits that are excited from one winding, i.e., magnetic circuits that are singly excited. Certain conclusions, however, can be drawn from the study of singly excited circuits that apply also to multiply excited circuits.