AN1625 STMicroelectronics, AN1625 Datasheet - Page 27

• Manufacturer Part Number: AN1625
• Description: L6235 THREE PHASE BRUSHLESS DC MOTOR DRIVER
• Manufacturer: STMicroelectronics

Figure 29. Control loop block diagram.
Can be noticed that since the motor is current controlled, the electrical time constant of the motor (L/R) does not
appear in any transfer function.
With the following values, module and phase of G
K
D = 3.34 µNms/rad
J = 6.5 µkgm
T
n = 2
f
V
t
R
R
C = 33 nF
R
R
R
tacho
pulse
M
R
T
pullup
m
fb1
fb2
1
2
SENSE
V
= J/D = 1.95 s (mechanical pole at 0.08 Hz)
= 9.8 mNm/A
= 5.6 k
= 1.8 k
= 4 mNm
speed
= 2618 rad/s (25000 r.p.m.)
= 100 k
= 1 M
= 1 ms
= n
= 5V
[V]
= 0.33
m
/ 2 = 833 Hz
2
<v
+
_
TACHO
> [V ]
G
R
R
op-amp
fb
fb
1
2
V
pullup
G
2
G
t
1
pulse
loop
+
- v
1
s
s
n
I
=
–
----------------------------------------------------------------------
G
+
D
loop
op amp
M
–
+
[rad/s]
1
<v
are shown in Figure 30.
+
Op-Amp
[V]
s
I
G
>
–
1
1
v
/ 1
+
+
G
G
s
s
D
motor
1
R
M
M
1
k
R
+
T
2
AN1625 APPLICATION NOTE
R
2
_
<v
T
+
ref
G
R
> [V]
T [Nm]
[Nm]
1
R
SENSE
1
k
<I
T
pk, Motor
> [A]
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