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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
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