Home / Technical Notes / Magnetic analysis / When the nonlinear calculation (B-H Curve) does not converge

If nonlinear calculation (B-H Curve) does not converge

If material is defined by B-H curve or M-H curve in the magnetostatic analysis, calculation is nonlinear.

Iterative calculations (Newton-Raphson method) are used in Femtet as nonlinear calculation cannot be solved by one operation.

The iterative calculations sometimes do not converge.

Try some of the following.

Check if the B-H curve is not smooth (does not increase monotonically) due to the measurement error. If so, make adjustment to make the curve increase monotonically and smoothly.
Go to [Analysis Condition Setting]-[High-Level Setting]-[Nonlinear Analysis Setting], and enter small deceleration factor.
Default setting is 1.0. Change it to 0.5 or 0.1. Calculation will all the more converge with smaller factor value, but it will increase the iterations and take longer time.
If the number of iterations is not sufficient, go to [Analysis Condition Setting]-[High-Level Setting]-[Nonlinear Analysis Setting], and increase the maximum number of iterations.

Dialog box of nonlinear analysis in the [High-Level Setting].