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The Question of The Back Electromotive Force (BEMF) observer

Question asked by 董培 董 on Nov 1, 2019
Latest reply on Nov 15, 2019 by Matej Pacha


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:

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

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


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