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9. Trip Signal Synthesis Circuit
@
Fig. 9-1 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 !p cut signal and reset signal.
8J-HIC
Fig. 9-1
Trip Signat Synthesis Circuit
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Table 9-1 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.
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Pins @ @ of the micro computer change from "Lo" to "Hi" alternately and supply signals to PQ2-PQ7.
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The chopper signal from the micro computer is inverted by Q307, and turns on or off PQ2-PQ4, 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 PQ5-PQ7 is stopped, and the lower arm transistor
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 D301 and D304, and turns off the drive signal in the same way as when the reset signal is "Lo".
Table 9-1 Circuits to which trip signals are transferred
[Sten curentinisgnel ————SC«tS
CO
[Peck curentcutoftsinl
[| O.-|_ Oo.
OO
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