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To have a more regulated start-up, it is recommended to enable the ForceAngle flag. When ForceAngle is enabled, the estimated angle is generated by emulating the angle from a rotor moving at a fixed frequency, as set by the user through the variable USER_FORCE_ANGLE_FREQ_Hz. This emulated rotating angle is used until the frequency estimated from FAST is greater than a user prescribed limit set by USER_ZEROSPEEDLIMIT. It is always recommended to keep the FORCE_ANGLE_FREQ at least two times greater than the ZEROSPEEDLIMIT frequency to insure that the rotor will actually be driven beyond the low speed limit needed for FAST to generate a reasonable estimate.
For example, if it is determined in testing that FAST is providing reasonable estimates at 2 Hz, you would set the following two variables:
// When ForceAngle flag is enabled USER_ZEROSPEEDLIMIT * USER_IQ_FULL_SCALE_FREQ_Hz = the frequency limit where FAST will be use instead of the ForcedAngle:
#define USER_FORCE_ANGLE_FREQ_Hz (4.0)
// Guarantees that the emulated excitation is larger than the frequency limit to provide more robust start-up.
