Motorola M68HC08 Reference Manual page 49

[1]
T_Cmt
T_Cmt
T2[1]
n=1
Per_CmtStart
T_ZCros[0]
Figure 3-20. Calculation of the Commutation Times During the Starting
3.3.1.5 Starting — Commutation Time Calculation
DRM028 — Rev 0
MOTOROLA
Freescale Semiconductor, Inc.
[2] [3]
T_Cmt
T2[2]
n=2
2*Per_ZCrosFlt[n-1]
2* Per_CmtStart
ZERO CROSSING
DETECTION SIGNAL
ZERO CROSSING
DETECTION SIGNAL
ZERO CROSSING
DETECTION SIGNAL
Per_Toff[n]
(Back-EMF Acquisition) State
Even the sub-states of the commutation process in the starting
(back-EMF acquisition) state remain the same as in the running state.
The required commutation timing depends on application state (starting
state, running state). So the commutation time calculation is the same as
that described in
Running — Commutation Time
computation coefficients are different:
coefficient Coef_HlfCmt = 0.125 with advanced angle
Advance_angle: 60Deg*3/8 = 22.5Deg
at Starting state!
BLDC Motor Control
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T2[n]
n=3
COMMUTATION IS PRESET
COMMUTATED AT PRESENT TIME
NO BACK-EMF FEEDBACK WAS RECEIVED
CORRECTIVE CALCULATION 1
T2*[n]
COMMUTED WHEN CORRECT
BACK-EMF FEEDBACK
Per_HlfCmt[n]
RECEIVED AND EVALUATED
T_ZCros[n]
T2**[n]
COMMUTATED WHEN BACK-EMF
ZERO CROSSING IS MISSED
CORRECTIVE CALCULATION 2.
Per_HlfCmt[n]
Calculation, but the following
BLDC Motor Control
Used Control Technique
Designer Reference Manual
49