Trip Signal Synthesis Circuit; Circuits To Which Trip Signals Are Transferred - Hitachi RAS-25CNH1 Service Manual

9. Trip Signal Synthesis Circuit

Fig. 9-1 shows the trip signal synthesis circuit.
This circuit is provided to stop the drive signal, etc. according to whether or not the Ip cut signal or reset
signal is present.
Table 9-1 shows to which circuits the various modulation signals are transferred.
For example, the chopper signal is only transferred to the upper arm transistor drive circuit, and the reset
signal is transferred to the micro computer and upper and lower arm transistor drive circuits.
On the other hand, pins ‹-° of the HIC-1 change from "Lo" to "Hi" alternately and supply the voltage
to PQ501-PQ503 and PQ601-PQ603.
The chopper signal from the micro computer is inverted by Q1 and turns PQ501, PQ502 or PQ503 ON
or OF to which voltage is applied at a high frequency to supply curent, thus transferring the upper arm
drive signal.
When the reset voltage is "Lo", the base of Q2 goes "Lo", to turn Q2 OFF and also stops the operation
current of PQ601-PQ603 to switch OFF the lower arm drive signal. With the upper arm transistor drive
circuit, the base of Q1 goes "Lo", and the micro computer stop supplying a voltage to PQ501-PQ503, thus
switching OFF the drive signal.
The peak current cut off (Ip cut) signal fixes the base of Q1 and Q2 in the upper/lower arm transistor drive
circuits at "Lo" to switch OFF the drive signal in the same way as when the reset voltage is "Lo".
Modulated signals
Chopper signal
Start current limit signal
Peak current cut off signal
Reset signal
Micro
computer
AX-8E21
RESET 17
OV OV
U +
29
V +
26
W +
27
Chopper
57
U +
26
V -
25
W -
24
5V
22
1p
OV
OV
Fig. 9-1 Trip Sigmal Synthesis Circuit
Table 9-1 Circuits to which trip signals are transferred
Circuit
Micro Computer
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– 83 –
HIC - 1
5V
1
R232
OV OV
Normal: Hi
OV
2
Reset: Lo
R223
35
R224
OV
37
R225
OV
36
7
OV
Q1
OV R226
35
R227
OV
34
R228
OV
33
32
OV
Q2
OV
Ip Cut off
Upper arm transistor
drive circuit
12V
Z0301
PQ501
PQ502
PQ503
PQ601
PQ602
PQ603
Lower arm transistor
drive circuit
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