IVT GS-XP12HR-N Service Manual page 20

GSXP12HRN
5.1.2 DC overcurrent detection circuit
When a current of about 25 A or higher flows through the shunt resistance (R49) on the control printed circuit board (PCB), the voltage at this resis-
tance is input to IPM CIN pin (26). Then, the gate voltage of the lower-phase IGBT (LU, LV, LW) inside the IPM turns OFF to cut off the overcurrent. At
the same time, an L output of about 1.8 ms is generated from IPM Fo pin (24), and this results in an L input to overcurrent detection input pin (34) of
the microcomputer (IC1) and turns OFF the PWM signal output (IC1 pins (51) through (56)) to the IGBT gate.
Protection circuit status
(Lower phase)
Internal IGBT gate
Output current Ic (A)
Sense voltage relative
to shunt resistance
Error output Fo
IPM
detection
6. 120° energizing control (digital position detection control)
This control system detects the digital position detection signal and adjusts the rate of acceleration/deceleration accordingly.
The motor's induced voltage waveform is input to the comparator in the form of PWM-switched pulse waveform, and a position detection signal is
generated as a reference voltage equaling 1/2 of 280 VDC. However, since there is no induced voltage waveform when the PWM waveform is OFF,
the microcomputer performs internal processing so that detection is enabled only when it is ON. Based on the detected position signal, actual PWM
waveform output timing is determined. Since it does not use a filter circuit, the detection accuracy is high.
(About 22 A)
a1
SC reference voltage
P
N
overcurrent CiN
circuit 26
FO
24
SET
SC
Delay by CR time constant circuit
About 1.8 ms
Shunt resistance
Overcurrent
R49
2 – 14
RESET
5V
IC1
34
0V