SLUUDM5 March 2026 MSPM0G1507 , MSPM0G1519 , MSPM0G3507 , MSPM0G3519
Using the motor’s data sheet, the user can input the motor's BEMF constant Ke in mV/Hz and program mtrBEMFConst as Ke × 10. For example, if a motor’s BEMF constant is 40mV/Hz, then user should set mtrBEMFConst = 400.
Sometimes the motor data sheet clarifies motor's BEMF constant with a different unit. Use Equation 36 and Equation 37 to convert it to 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 period Tp in seconds. The following figure shows the test motor waveform captured by a scope. Then, users can calculate BEMF constant Ke as shown in Equation 38.