Saturation in Magnetic core (Simscape) failure

Hi,

I recently tried to design a transformer core in MATLAB using the Simscape Magnetic Core block. I set all the parameters according to my calculations and defined the hysteresis curve for the core using a saturated BH curve. Just like the example, I have used descending B and H values. I have at least three values (1400, 2000, and 4000 A/m) that correspond to the same B_sat value, and similarly for the negative side (-1400, -2000, -4000 A/m) with -B_sat in the array. The saturation point is set at B_sat as well.

The issue is that when I feed a sine voltage with an amplitude that should saturate the core (the number of turns, Ae, Le, and frequency are all calculated to reach B_sat at this amplitude), my actual B value remains lower than B_sat. When I increase the voltage amplitude well beyond the calculated saturation point, B still does not clamp at B_sat. Instead, it maintains a sine waveform with peaks greater than B_sat (for example, with B_sat = 0.5T, the peak B reaches 0.8T).

As expected, the magnetizing current increases rapidly as soon as B exceeds B_sat and follows the same waveform while B > B_sat, then returns to normal once B < B_sat again (since it’s a sine wave).

What could cause this issue? I am using a fixed-step solver. Any suggestions? Am I missing something in my setup?

P.S. The BH curve includes all the necessary points (remanence, coercive force) and flattens out at the saturation extremes.

Thanks in Advance!

Answer 1

[Kautuk Raj]

I understand that the issue is occurring because your BH curve in Simscape is not flat enough at the saturation region. To ensure B clamps at B_sat, add several points with increasing H but the same B_sat value at both positive and negative extremes (e.g., H = 1400, 2000, 4000, 8000 A/m all with B = 0.5T). This prevents Simscape from interpolating or extrapolating B above B_sat.

Also, try reducing your solver step size or use a variable-step solver for better accuracy. Double-check your units and core geometry as well.

Refer to the following documentation page from MathWorks: https://www.mathworks.com/help/sps/ref/magneticcore.html