SPRUHJ1I January 2013 – October 2021 TMS320F2802-Q1 , TMS320F28026-Q1 , TMS320F28026F , TMS320F28027-Q1 , TMS320F28027F , TMS320F28027F-Q1 , TMS320F28052-Q1 , TMS320F28052F , TMS320F28052F-Q1 , TMS320F28052M , TMS320F28052M-Q1 , TMS320F28054-Q1 , TMS320F28054F , TMS320F28054F-Q1 , TMS320F28054M , TMS320F28054M-Q1 , TMS320F2806-Q1 , TMS320F28062-Q1 , TMS320F28062F , TMS320F28062F-Q1 , TMS320F28068F , TMS320F28068M , TMS320F28069-Q1 , TMS320F28069F , TMS320F28069F-Q1 , TMS320F28069M , TMS320F28069M-Q1
The last parameter required from the motor's datasheet is the rated flux. This particular one can be calculated from the provided parameter, Back EMF constant, or Ke, which is provided in Vpeak/kRPM. The following unit conversion is needed in order to set the value correctly the header file:
The resulting value is then written in user.h as follows:
#define USER_MOTOR_RATED_FLUX (0.0402)
It is also common that the rated flux of the motor is not provided by the motor manufacturer's datasheet, and an alternative way to measure the rated flux is by measuring the phase-to-phase voltage when the motor to be measured is spun by another motor. In other words, we run the motor in generator mode, and connect an oscilloscope on the motor phases to see the voltage production at a given speed. The speed to run the motor in generator mode to measure flux should be high enough to overcome any cogging torque. For example, considering the same motor, we run it with another motor connected to its shaft, and plot the phase to phase voltage. In this example we run the motor at about 1000 RPM, but can be any speed as long as the motor runs at a constant speed. Figure 7-57 shows the result.
Considering 4 pole pairs, and the fact that Ke is in Vpeak/kRPM, the measured Ke with the oscilloscope is:
And to calculate what we configure in user.h is as follows, based on the measured value:
This can also be calculated straight from the oscilloscope measurement as follows:
#define USER_MOTOR_RATED_FLUX (0.0404)