Motorola M68HC08 - Manual (Page 42)

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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