Hi Daniel,
About the model of S12ZVM_FOC_Sensorless,shown as below, i wanna make sure the IdEObsrv(Part A shown) and IqEObsrv(Part B shown) is EMF or not ? i thought is EMF, my reason ,EMF contains the position and speed of rotor, to get the Postion of the rotor using the arctan() Function,namely Theat=arctan(EAlpha/EBeta),
and there is another doubt that the -1*2^15 in Part C,why we multiplied the -1*2^15 with IdEObsrv?
Hi Eden Li,
I'm not the originator of this model but i'm going to try to explain as best i can.
For sensorless application there basically 2 types of rotor position/speed estimation methods:
- based on back-EMF that is produces in the stator windings
- based on magnetic saliency - a fancy way to say that Ld!=Lq
The method based on back-EMF is relatively simple but is has a major drawback: it does not work for low speeds - when the back-EMF generated is too small to be used for any digital acquisition. For mid-high range application it is ok and robust enough.
On the other hand, the magnetic saliency method can work at any speed but requires a much more complex mathematical apparatus and consequently processing power. Hopefully the NXP processor can deliver all the juice to employ such a method.
I made this introduction - just to explain the background and set the stage for the magnetic saliency algorithm.
The model implemented in the example is based on this method. The main equation that describes the method is.
The "-1" scaled in Q15 is a trick to optimize the math computations within Simulink Model.
Bottom line all that model implements something like this
Hope this clarify both questions.
Best regards,
Daniel