Error in simscape mutual inductance documentation

The page found here: https://www.mathworks.com/help/physmod/sps/powersys/ref/mutualinductance.html#d123e30549 has an error. In the Equations section, the following bullet point is found.

• Lm is the mutual inductance, such that Lm ≤ √L1⋅L2

However, if L1=L2 then Lm=L1=L2 and simulink will throw an error "Parameter error in 'Mutual Inductance1' block, winding 1. Self-inductance and mutual inductance must have different absolute values."

In practice this makes sense that Lm < sqrt(L1*L2) due to losses in the core of the inductor. The documentation should match the simulation result.

Answer 1

[Sayan]

Hi @Aaron Vaughan,

I understand that you are finding a disparity in the documentation of the Mutual Inductance block. You rightly mentioned that the mutual inductance in all real systems is always less than the self-inductance due to the leakage involved. In response to your query, I have the following two points to mention:

1. When the values of "L1", "L2", and "Lm“ are assigned the same, the overall inductance matrix "L" (refer to the Equations section of the documentation) becomes a singular matrix that is not accepted by MATLAB.
2. In the Mutual Impedance subsection in the documentation (https://in.mathworks.com/help/releases/R2021a/physmod/sps/powersys/ref/mutualinductance.html?s_tid=doc_ta#:~:text=1.1e%2D03%5D.-,Mutual%20impedance,-The%20mutual%20resistance) a coupling coefficient “k” has been introduced in the equation. The absolute value of "k" is less than 1 for all real systems. In the documentation "k" is taken to be less than or equal to 1 to include the ideal scenario.

Hope this answers your query.