Motorola M68HC08 manual Alignment, Running

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

BLDC Motor Control

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:

Designer Reference Manual		DRM028 — Rev 0
40	BLDC Motor Control	MOTOROLA
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