SLAU948 October 2024 MSPM0G3507
Using the motor’s data sheet, the user can input the motor's BEMF constant Ke in mV/Hz and program mtrBEMFConst in the System Configuration Page as Ke × 10.
Equation 4 and Equation 5 can be used to convert Ke in mV/rpm, mV*sec/rad and torque constant Kt to Ke in mV/Hz.
If the motor does not have a data sheet, measure the voltage across any two phases of the motor using an oscilloscope by manually spinning the motor. A sinusoidal or trapezoidal voltage appears on the oscilloscope. Measure the peak voltage Ep in milli-volts and time period Tp in seconds. Calculate BEMF constant Ke as shown in Equation 6.