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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.
●
When pin
°
of HIC goes "Hi"
[
"Lo", a photocoupler between PQ501 pins
1
and
2
turns on and current
flows to terminal d
[
R501
[
PQ501
[
R504
[
power module’s Bu+ terminals
[
Eu+ terminals
[
D502
[
D501
[
terminal e 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 PQ501 -
PQ503 via driver IC1.
Fig. 7 - 1
Fig. 7 - 2 Forward Current Waveform at Point
A
