The Question of The Back Electromotive Force (BEMF) observer

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The Question of The Back Electromotive Force (BEMF) observer

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Contributor II

Hello!!!

I have been reading the document<MC9S12ZVMMCLUG> recently, it's not particulayly clear about the AMCLIB_BemfObsrvDQ.I hope I can get your help, Thanks!!!

The BEMF observer fits the input voltages and currents to a mathematical model of the
motor. The model mirrors the behavior of the PMSM; see the following equation:

pastedImage_1.png

But,The mathematical model of the motor should be the following equation:

pastedImage_2.png

The red mark is different.The document explains it as follow:

pastedImage_3.png

But I still dont't know why,I hope to get a detailed explanation. Thank you very much!!!

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2 Replies

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NXP Employee
NXP Employee

Hi,

The model introduced in the AppNote uses "extended back-EMF", which is different from the actual EMF. Please refer to the following picture. Full explanation would basically do the same as set of articles on IEEE (https://ieeexplore.ieee.org/search/searchresult.jsp?newsearch=true&queryText=extended%20back%20emf%2...)

bemf.png

I hope it helps,

Matej

111 Views
Contributor II

Hi,

I will read the articles on IEEE, thank you very much

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