topic AN4680 in Other NXP Products

AN4680

Ederson1510 — Tue, 16 Aug 2022 16:56:35 GMT

Hello

I used the application note AN4680 to determine the inductances of a PMSM motor in my doctoral thesis. They are questioning me, saying that the expression L=2/3 tauR is not correct, that the 2/3 should be unitary. According to my teacher, 2/3 L / 2/3 R is L/R. Can anyone help me in the development of the AN4680 expression?

Re: AN4680

_Leo_ — Fri, 26 Aug 2022 01:40:47 GMT

Thank you so much for your interest in our products and for using our community.

Let me take a look into this, so please give me more time to reach you back with a proper answer.

On the other hand, I know that the equations are not developed in that document. But could you please explain in more detail the argument of your teacher? Perhaps with the use of parentheses it would help us not to fall into a misunderstanding. A reference would be helpful too.

Have a nice day!

Re: AN4680

Ederson1510 — Fri, 26 Aug 2022 11:04:03 GMT

According to my teacher:

The equivalent impedance is 3/2 (R+sL).

The time constant seen by the source is (3/2)L/(3/2)R = L/R.