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AYXP12FRN

2 – 15

4.1.2 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.

SET

RESET

(About 22 A)

SC reference voltage

Delay by CR time constant circuit

About 1.8 ms

Protection circuit status

Output current Ic (A)

Sense voltage relative

to shunt resistance

Error output Fo