Average Force in an Eddy Current Solution

The Lorentz force and virtual force computed for an eddy current model represent the average force, not the instantaneous force at a specific point in the AC magnetic field's cycle. Similarly, the Lorentz torque and virtual torque represent the average torque over time, since these torque computations make use of the time-averaged force. The difference between the time-averaged (or DC) force, AC force, and instantaneous force is shown below:

Force oscillates at twice the frequency of the source current and magnetic field:

where:

• f_F is the frequency of the force.
• f_S is the frequency of the source current and magnetic field.
• T_F is the period of the force.

The time-averaged (or DC) force, AC force, and instantaneous force can be determined by:

The AC force, F_AC must be evaluated at a particular phase (=wt) in order to determine its magnitude at an instant in time.