Motorola M68HC08 Reference Manual page 42

BLDC Motor Control
3.3.1.3 Running — Commutation Time Calculation
Designer Reference Manual
42
Freescale Semiconductor, Inc.
COMMUTATION DONE
BEMF ZERO CROSSING
DETECTED BETWEEN PREVIOUS
COMMUTATIONS?
YES
SERVICE OF COMMUTATION:
PRESET COMMUTATION
WAIT FOR PER_TOFF UNTIL PHASE
CURRENT DECAYS TO ZERO
BEMF ZERO CROSSING
MISSED?
NO
BEMF ZERO CROSSING
DETECTED?
NO
NO
HAS COMMUTATION
TIME EXPIRED?
YES
Figure 3-16. BLDC Commutation with Back-EMF
Zero Crossing Sensing Flowchart
Commutation time calculation is shown in
BLDC Motor Control
For More Information On This Product,
Go to: www.freescale.com
NO
CORRECTIVE CALCULATION 1.
BEMF ZERO CROSSING MISSED
YES
CORRECTIVE CALCULATION 2
SERVICE OF RECEIVED BEMF
YES
ZERO CROSSING:
CORRECTED SETTING
OF COMMUTATION TIME
HAS COMMUTATION
TIME EXPIRED?
YES
MAKE MOTOR COMMUTATION
Figure
CORRECTED SETTING
OF COMMUTATION TIME
NO
3-17.
DRM028 — Rev 0
MOTOROLA