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I'm not sure if it is possible to estimate the flux linkage of a PMSM motor (star connection) by the controller itself, where I can measure the input voltage, all the phase currents and the velocity. Measurements of R and L are also available.

The flux linkage is defined as:

$$ \lambda_m = \sqrt{2/3} \frac{2}{P} K_b $$

Where P=Number of Poles and Kb theback EMF constant. So I need to come up with Kb first, but I don't know how I could achieve this. When I turn on the power supply to speed up the motor to a constant speed, I cannot measure the back EMF, because I can only measure the input voltage. Is it even possible to measure the flux linkage with this setup?

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  • \$\begingroup\$ Can't you measure back-emf by measuring the voltage over the running but (temporarily) disconnected motor? \$\endgroup\$ – HarryH Jun 13 '19 at 22:30
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It is indeed possible, to do so take a look at the work done in the following paper: Sensorless Adaptive Speed Control for PMSM Drives

Within this paper it is explained how to get the flux linkeage. Afterwards it is shown how to estimate this flux variation to estimate the rotor speed:

enter image description here

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