How to properly configure thermistor measurement for ST Motor Control Workbench and Motor Pilot

[KConn.2]

I am using an EVALSTDRIVE101 and have it all setup to run my motor no problem. I am using:

Motor control workbench v5.Y.3

The user guide for the EVALSTDRIVE101 says the equation for the thermistor on the board is: T °C = 45.7 ⋅ VTP19 V + 23.6

In Motor control workbench i set:

• V0 to 275mV, because that is the voltage at room temp because the thermistor is 10K, divided with 910 ohm resistor, and Vdd is 3.3V.
• Then i set T0 to 23.6, because that is what the equation indicates i believe
• then dV/dT i set to 21.9 because if you look at the equation and the units you should get 1 when multiplying this value by 45.7, and i derived it with 1/45.7

When i generate this code and load it to my control board, in this case Nucleo 446RE, i can see the temperature readout from ST motor pilot, and the room temperature looks correct, but as I run my motor (about 400W) the board is getting warm and an IR thermometer will say something like 40C but the readout on ST motor pilot has only increased to maybe 32 or 33C. Clearly not enough, obvious by touch that it is more than ~33C.

Does anyone know the correct way to derive the values for the ST motor control workbench? My problem is likely for the dV/dT value.

Thank you,

-Kyler

[GMA]

Dear Kconn,

Firstly, we would like to sincerely apologize for the delay in replying to your post.
If your point is still pertinent, please have a look to "Temperature sensor" chapter in UM2781 document.
As mentioned, we use a linear approximation that targets a range between 50°C and 120°C. 
In figure 11, you can see that for lower temperature than 50°C, linear approximation will underestimate it.