4.1.2 DC over current detection circuit
When a current of about 25 A or higher ows through the shunt resistance (R49) on the control printed circuit board (PCB), the voltage
at this resistance is input to IPM CIN pin (15). 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 more than 20μs is generated from IPM Fo pin (14), and this results in an L input
to over current 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 25 A)
SC
SC reference voltage
Delay by CR time constant circuit
More than 20
a1
Protection circuit status
Output current Ic (A)
Sense voltage relative
to shunt resistance
Error output Fo
(Lower phase)
Internal IGBT gate
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