BLDC Motor Control
Designer Reference Manual DRM028 — Rev 0
40 BLDC Motor Control MOTOROLA
The current controller subroutine, with PI regulator, is called to control
dc-bus current. It sets the correct PWM ratio for the required current. The
current PI controller works with constant execution (sampling) period.
This period should be a multiple of the PWM period, in order to
synchronize the current measurement with PWM:
Current controller period = n/PWM frequency
The BLDC motor rotor position with flux vectors during alignment is
shown in Figure 3-15.
Figure 3-15. Alignment
3.3.1.2 Running
The commutation process is a series of states which assure:
• The back-EMF zero crossing is successfully captured
• The new commutation time is calculated
• The commutation is performed
The following processes need to be provided:
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