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Alignment – Motorola M68HC08 User Manual

Page 40

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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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Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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