Hitachi RAS-25QH1 Technische Information Seite 181

10. Trip Signal Synthesis Circuit
@ Fig. 10-1 shows the trip signal synthesis circuit.
This circuit uses the upper and lower arm transistor drive signals to modulate the chopper signal or stops
the drive signal, according to the presence or absence of the Ip cut signal and reset signal.
CHOP-HICA
Reset circuit
Outdoor
microcomputer
Fig. 10-1 Trip Signal Synthesis Circuit
@ Table 10-1 shows the circuits to which the modulated signals are transferred.
For example, the chopper signal is transferred only to the upper arm transistor drive circuit, and the reset
signal is transferred to the microcomputer and upper and lower arm transistor drive circuits.
e Pins @3 @8 of the micro computer change from "Lo" to "Hi" alternately and supply signals to
PQ401-403 and PQ411-413.
@ The chopper signal from the micro computer is inverted by Q4, and turns on or off PQ401-403, to which
voltage is supplied, with high frequencies, to let current flow to them to transfer the upper arm drive signal.
@ When the reset voltage is "Lo" , the current operating PQ41 1-413 is stopped, and the lower arm transi-
stor drive signal is turned off. With the upper drive arm transistor circuit, the voltage supply to PQ401-403
is stopped in the same way, and the drive signal is turned off.
@ The peak current cut off (Ip cut off) signal fixes the voltage at upper and lower arm drive circuits to "Lo"
via D2 and D4, and turns off the drive signal in the same way as when the reset signal is "Lo" .
Table 10-1 Circuits to which trip signals are transferred
' Upper arm transistor
Modulated signals Circuit ] Microcomputer ig drive circuit
Chopper signal ee Oe
Stat curent iit signal ee eae Or
Lower arm transistor
drive circuit
Peak current cut off signal
Reset signal
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