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Commutation control stages – Motorola M68HC08 User Manual

Page 39

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BLDC Motor Control

Used Control Technique

DRM028 — Rev 0

Designer Reference Manual

MOTOROLA

BLDC Motor Control

39

position is known, and can be used to calculate the speed and
processing of the commutation in the running state.

Figure 3-14. Commutation Control Stages

3.3.1.1 Alignment

Be

fore the motor starts, there is a short time (depending on the motor’s

electrical time constant) when the rotor position is stabilized by applying
PWM signals to only two motor phases (no commutation). The current
controller keeps current within predefined limits. This state is necessary
in order to create a high start-up torque. When the preset time-out
expires then this state is finished.

ALIGNMENT

STARTING

(BACK-EMF ACQUISITION)

RUNNING

ALIGNMENT TIME

EXPIRED?

START MOTOR

MINIMAL CORRECT

COMMUTATIONS DONE?

NO

YES

YES

NO

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Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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