Hitachi RAS-25CNH1 - Lower Arm Drive Circuit Analysis; Lower Arm Drive Circuit Diagram

– 77 –
(2) Lower Arm Drive Circuit
● Fig. 7-4 shows the lower arm drive circuit.
The circuit configuration is completely the same for phases A, B and C.
● When pin fi of the micro computer goes "Hi" [ "Lo", a photocoupler between PQ601 pins 1 and 2 turn
off and reverse bias current flows to C411 [ power module's Ew
–
terminals [ Bu
–
terminals [ R604
[ PQ601 to cut off the lower arm transistors. (Fig. 7-5)
● R607 is used to charge C601 initally.
● The operation is the same for B
–
and C
–
phases.
● When the peak current cut off function operates, HIC-1 º pins become 0V, PQ501-PQ503 and PQ601-
PQ603 turn off and the upper/lower arm drive circuits stop.
● when a reset signal is applied, HIC pins 7 and ¤ become open, PQ501-PQ503 and PQ601-PQ603 turn
off and the upper/lowerarm drive circuits stop.
● When pin fi of the micro computer goes "Lo" [ "Hi", a photocoupler between PQ601 pins 1 and 2 turns
on and current flows to terminal i [ R601 [ PQ601 [ R604 [ power module's BU
–
terminals [
Ew
–
terminals [ D602 [ D601 [ terminal k and drives the lower arm transistors. (Fig. 7-4)
● The signals which turn on or off according to the position detection signals are output from pins ‹›fi
of the micro computer in the same way as in the upper arm drive circuit and are input to pins 1 of
photocouplers P601 and PQ602 via driver IC1.
● No chopper signal is input to the lower arm drive circuit.
1
2
5
6
1
2
1
8
2
PQ5
PQ6
PQ7
7
5
6
8
7
7
8
5
6
c
R411
R414
R412
R415
R413
R416 R417
C411
CN28
Ew
Bw
-
Bv
-
Bu
-
Power module
A
-
phase
B
-
phase
C
-
phase
Fig. 7-4
D411 D412
d
1
2
5
6
1
2
1
8
2
PQ5
PQ6
PQ7
7
5
6
8
7
7
8
5
6
R411
R414
R412
R415
R413
R416 R417
C411
CN28
Ew
Bw
-
Bv
-
Bu
-
Power module
A
-
phase
B
-
phase
C
-
phase
Fig. 7-5
D411 D412