AS5040-ASST View Datasheet(PDF) - austriamicrosystems AG
Part Name
Description
MFG CO.
'AS5040-ASST' PDF : 61 Pages View PDF
AS5040 â Brushless DC Motor Commutation Mode
Brushless DC Motor
Commutation Mode
(EQ3)
Brushless DC motors require angular information for stator
commutation. The AS5040 provides U-V-W commutation
signals for one and two pole pair motors. In addition to the
three-phase output signals, the step (LSB) output at pin 12
allows high accuracy speed measurement. Two resolutions (9
or 10 bit) can be selected by programming Div0 according to
Figure 36.
Mode 3.0 (3.1) is used for brush-less DC motors with one-pole
pair rotors. The three phases (U, V, W) are 120 degrees apart,
each phase is 180 degrees ON and 180 degrees OFF.
Mode 3.2 (3.3) is used for motors with two pole pairs requiring
a higher pulse count to ensure a proper current commutation.
In this case the pulse width is 256 positions, equal to 90 degrees.
The precise physical angle at which the U, V and W signals
change state (âAngleâ in Figure 31 and Figure 32) is calculated
by multiplying each transition position by the angular value of
1 count:
Angle [deg] = Position x (360 degree / 1024)
Figure 31:
U, V and V-Signals for BLDC Motor Commutation (Div1=0, Div0=0)
Commutation - Mode 3.0 (One-pole-pair)
Width: 512 Steps
U
Width: 512 Steps
V
W
CW Direction
Position: 0
Angle: 0.0
171
60.12
341
119.88
512
180.0
683
240.12
853
299.88
0
360.0
Figure 32:
U, V and W-Signals for 2-Pole BLDC Motor Commutation (Div1=1; Div0=0)
Commutation - Mode 3.2 (Two-pole-pairs)
Width: 256 Steps
Width: 256 Steps
U
V
W
CW Direction
Position: 0
Angle: 0.0
85
29.88
171
60.12
256 341 427 512 597 683 768 853 939
0
90.0
119.88 150.12
180.0
209.88 240.12 270.00 299.88 330.12
360.0
Page 28
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[v2-12] 2017-Jun-20
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