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Motorola M68HC08 User Manual

Page 42

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BLDC Motor Control

Designer Reference Manual

DRM028 — Rev 0

42

BLDC Motor Control

MOTOROLA

Figure 3-16. BLDC Commutation with Back-EMF

Zero Crossing Sensing Flowchart

3.3.1.3 Running — Commutation Time Calculation

Commutation time calculation is shown in

Figure 3-17

.

SERVICE OF COMMUTATION:

BEMF ZERO CROSSING

WAIT FOR PER_TOFF UNTIL PHASE

MISSED?

BEMF ZERO CROSSING

DETECTED?

MAKE MOTOR COMMUTATION

BEMF ZERO CROSSING

DETECTED BETWEEN PREVIOUS

COMMUTATIONS?

CORRECTIVE CALCULATION 1.

PRESET COMMUTATION

CURRENT DECAYS TO ZERO

COMMUTATION DONE

NO

YES

YES

NO

NO

NO

YES

YES

NO

YES

BEMF ZERO CROSSING MISSED

CORRECTIVE CALCULATION 2

CORRECTED SETTING

OF COMMUTATION TIME

SERVICE OF RECEIVED BEMF

ZERO CROSSING:

CORRECTED SETTING

OF COMMUTATION TIME

HAS COMMUTATION

TIME EXPIRED?

HAS COMMUTATION

TIME EXPIRED?

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Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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