AN1627 Freescale Semiconductor / Motorola, AN1627 Datasheet - Page 7

• Manufacturer Part Number: AN1627
• Description: Low Cost High Efficiency Sensorless Drive for Brushless dc Motor Using MC68HC (7)05MC4
• Manufacturer: Freescale Semiconductor / Motorola

quite a lot because the three phase system, created by the power stage, is not symmetrical. If it was
symmetrical, u
the motor construction (u
phase A can be sensed within the following intervals: 330°-30° and 150°-210°.
AN1627
REV 0.2
0
would equal zero. The expression of u
0
0
0
0
0
iA,B,C
30
30
30
30
30
Freescale Semiconductor, Inc.
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60
60
60
60
60
) and the implemented three phase system (u
Figure 2-4.
90
90
90
90
90
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120
120
120
120
120
150
150
150
150
150
-20° switching angle
180
180
180
180
180
210
210
210
210
210
0
(see (EQ 2-1.)) explains how this depends on
240
240
240
240
240
270
270
270
270
270
300
300
300
300
300
330
330
330
330
330
uiA
PsiA
360
360
360
360
360
Torque
u0
vA,B,C
id0
iA
uVA
uA
390
390
390
390
390
). The Back-EMF of
MOTOROLA
7