OM9373 International Rectifier Corp., OM9373 Datasheet - Page 7

• Manufacturer Part Number: OM9373
• Description: Full-featured Power Module For Direct Drive Of 3-phase Brushless Dc Motor F-43 / Mp3-43l Packages
• Manufacturer: International Rectifier Corp.

FROM MOTOR HALL SENSORS
Figure 3 represents the implementation of a typical
current-mode controller for torque control. The load
current is monitored via the controller’s internal sense
resistor. The current sense signal is filtered and fed
into the current sense amplifier where the absolute
value of ISH-ISL is multiplied by two and biased up by
2.5V. Besides the implementation of the cycle-by-
cycle current limit/overcurrent protection feature of the
OM9373 discussed in the preceding paragraph, the
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Fig 3: Implementation of a Current-Mode Controller
CURRENT_COMMAND
+15V
H3
H2
H1
1k
3.24k
3.24k
OFFSET
35.6k
.26uF
1800pF
43k
4700pF
10uF
.1uF
+
232
232
.1uF
2k
10k
.1uF
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
1
2
3
4
5
6
7
8
9
Vcc
EA1-
EA2+
EA1+
VREF
EA2-
EA2_OUT
EA1_OUT
PWM_IN
OSCILLATOR
I_SENSE
ISH
ISL
QUAD_SEL
TACH_OUT
BRAKE
OV_COAST
SOFT_START
GROUND
H3_HALL_INPUT
H2_HALL_INPUT
H1_HALL_INPUT
SPEED_IN
DIRECTION
CSH
CSL
output of the current sense amplifier is fed into the
error amplifier which is configured as a differential
amplifier. An error signal representing the difference
between the current command input and the value
of the amplified current sense signal is produced.
Then it is compared to a pulse width modulated
ramp and since torque is nearly proportional to the
average phase output current, the torque controlled
via duty cycle control.
MOTOR_RETURN
MOTOR_RETURN
PHASE_A_OUT
PHASE_A_OUT
PHASE_B_OUT
PHASE_B_OUT
PHASE_C_OUT
PHASE_C_OUT
SOURCE_A
SOURCE_A
SOURCE_B
SOURCE_B
SOURCE_C
V_MOTOR
V_MOTOR
V_MOTOR
N/C
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
C_BUS
+
HALL SENSORS
C_FILT
OM9373
V_MOTOR
H1
H2
H3
MOTOR
7