# Calculate motor flux of a PMSM

I am struggling with the calculation of the motor flux for a RPX22-042V24 PMSM. I know back EMF, Torque constant and several other values from the datasheet. But I found different ways to calculate the flux and I am not sure if its correct to use back EMV in V/kRPM or V/RPM.

With the equation at the end of this page I get a flux of 4.15 mWb. Does this value make sense for this parameter?

• I found two ways for calculating the magnetic flux of a motor, but the results are very different. Maybe someone knows why? Option 1: According to the formula in the end of this page de.mathworks.com/help/sps/ug/… flux1=Kt/N=16.6mNm/A/4pole pairs=4.15mWb with Kt = torque constant Option 2: According to the formula from the SPMSM page de.mathworks.com/help/mcb/ref/surfacemountpmsm.html flux2=(2/3)*Kt/N=(2/3)*16.6 mNm/A/4pole pairs=2.77mWb The flux's unit is in both cases correct but whats the reason for the factor2/3 Sep 19, 2023 at 10:20
• This was helpful, do you have any literature where we can establish a relation between Motor speed and phase current at constant load?
– AK47
Apr 17 at 6:15