Hitachi RAS-25QH1 Technische Information Seite 169

8. Lower Arm Drive Circuit
Fig. 8-1 shows the lower arm drive circuit.
The circuit configuration is completely the same for phases A, B and C.
Power module
tie
A™~ phase
Fig. 8-1
@ When pin @ of the micro computer goes "HI" > "LO", a photocoupler between PQ411A pins © and @
turns on and current flows to terminal D->R411A—~PQ411A—-R414A— power module's Bu" terminals >
Ew" terminals—>D412A—D411A— terminal © and drives the lower arm transistors. (Fig. 8-1)
@ The signals which turn on or off according to the position detection signals are output from pins @ @
of the micro computer in the same way as in the upper arm drive circuit and are input to pins @ of
photocouplers PQ411A—PQ413A.
@ Nochopper signal is input to the lower arm drive circuit.
Power module
Bu-
A7 phase
B~ phase
Fig. 8-2
@ When pin @ of the micro computer goes "LO" — "HI", a photocoupler between PQ411A pins © and@
turn off and reverse bias current flows to C411A— power module's Ew terminals - Bu" terminals —
R414A—PQ411A to cut off the lower arm transistors. (Fig. 8-2)
@ R417A is used to charge C411A initally.
@ The operation is the same for B- and C™ phases.
@ When the peak current cut off function operates, CHOP-HIC pins © and © become OV,
PQ401A—PQ403A and PQ411A—PQ413A turn off and the upper/lower arm drive circuits stop.
@ When a reset signal is applied, CHOP-HIC pins © and © become OV, PQ401A—PQ403A and
PQ411A—PQ413A turn off and the upper/lower arm drive circuits stop.
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