– 56 –
7. Drive Circuit
(1) Upper Arm Drive Circuit
●
Fig. 7-1 shows the upper arm drive circuit.
The circuit configuration is completely the same for phases A, B and C.
5
6
1
8
5
7
2
6
C405
Bv+
Ev+
Bu+
Eu+
Bw+
Ew+
CN27
R402
R405
D403
D404
R408
C402
PQ3
+
–
5
6
1
a
A
b
8
7
2
C404
R401
R404
D401
D402
R407
C401
PQ2
+
–
5
6
1
8
9
7
2
10
A
A
C406
R403
R406
D405
D406
R409
C403
PQ4
+
–
Power module
U+phase
V+phase
W+phase
Fig. 7-1
Fig. 7-2 Forward Current Waveform at Point
1
2
Current at point
Forward
current
O
A
●
When pin
e
of the micro computer goes "HI"
[
"LO", a photocoupler between PQ2 pins
1
and
2
turns
on and current flows to terminal
A
[
R401
[
PQ2
[
R404
[
power module’s Bu+ terminals
[
Eu+
terminals
[
D402
[
D401
[
terminal
B
and drives the upper arm transistors. (Fig.7-2)
●
As described in the rotor magnetic pole position detecting circuit, the upper arm drive circuit supplies
current to the bases of the transistors on the power module's positive
e
side which turn on or off according
to the position detection signals. The signals according to the position detection detection signals are
output from pins
e
,
r
and
t
of the micro computer and are input to pins
2
of photocouplers PQ2 - PQ4.