Hitachi RAS-25QH1 Technische Information Seite 167

@ When pin @ of the micro computer then goes "LO" — "HI", a photocoupler between PQ401A pins @
and @ turns off and the reverse bias current flows to C401A— power module's Eu' terminals — Bu'
terminals >R404A>PQ401Ato cut off the upper arm transistors. (Fig. 7-3)
(8)
R401A
401 PQ401A R404A
Power module
At phase
On
Reverse
bias
Ho
hCUme Current at point ®
current
: "i
hi
Ee
Fig. 7-3 Waveform of Transistor Base Current (Reverse Current at Point @ )
@ R407A is used to charge C401A initally.
@ The operation is the same for B' and C* phases.
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