Hitachi RAS-25CNH2 - Lower Arm Drive Circuit

– 58 –
(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 y of the micro computer goes "LO" [ "HI", a photocoupler between PQ5 pins 1 and 2 turn
off and reverse bias current flows to C411 [ power module's Ew
–
terminals [ Bu
–
terminals [ R414
[ PQ5 to cut off the lower arm transistors. (Fig. 7-5)
● R417 is used to charge C411 initally.
● The operation is the same for V
–
and W
–
phases.
● When the peak current cut off function operates, Q306, PQ2-PQ4 and PQ5-PQ7 turn off and the upper/
lower arm drive circuits stop.
● Only the lower arm drive circuits turns off when reset.
● When pin y of the micro computer goes "HI" [ "LO", a photocoupler. between PQ5 pins 1 and 2 turns
on and current flows to terminal C [ R411 [ PQ5 [ R414 [ power module's BU
–
terminals [ Ew
–
terminals [ D412 [ D411 [ terminal D 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 y u i
of the micro computer in the same way as in the upper arm drive circuit and are input to pins 2 of
photocouplers PQ5-PQ7.
● 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
U
-
phase
V
-
phase
W
-
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
U
-
phase
V
-
phase
W
-
phase
Fig. 7-5
D411 D412