MT6M15962a
3. Protection functions
© Fuji Electric Co., Ltd. All rights reserved.
As described in Chapter 4
“Typical Application Circuits“, it is necessary to determine the
I
F
of the
primary side of the optocoupler so that the total current of the current flowing through the pull-up
resistor
I
R
and the constant current
I
in
can flow on the secondary side of the optocoupler.
If the
I
F
is insufficient, the secondary side may malfunction. However, since optocouplers have a limited
lifetime, it is necessary to consider the lifetime when selecting the primary side current limiting resistor.
In addition, the availability of the upper phase alarm signal output differs depending on the package.
Check the alarm specification of the IPM in Chapter 3.1, "List of functions".
6-5
3.1 General protection operation
3.1.1 Range of protection
• The protection function of IPM is designed to handle non-repetitive abnormal operations. Ensure that
abnormal operation is not repeated. In the worst case, the IPM may be destroyed. Over current and
short-circuit protection are guaranteed under the condition that the control power supply voltage is
from 13.5 to 16.5 V and the main power supply voltage is from 200 to 400 V (650 V series) or 400 to
800 V (1200 V series).
3.1.2 Action on occurrence of alarm signal output
• If an alarm signal is output, stop the input signal to the IPM and shutdown the system immediately.
• The protection functions protect the IPM against abnormal operation, but they are not able to
eliminate the causes.
• If an abnormal operation is detected in the upper arm, only the IGBT of the detected phase is turned
off and an alarm signal is output from the same phase (excluding P629 and P639). At this time,
Switching operation of other phases are permitted.
• On the other hand, when an abnormal operation is detected in the lower arm of the inverter part, all
the IGBTs in the lower arm of the inverter part are turned off regardless of the phase and an alarm
signal is output from the lower phase. At this time, Switching operation of the upper arm and brake
part are permitted.
When an abnormal operation is detected in the brake part, all the IGBTs of the lower arm(including
brake part) are turned off and an alarm signal is output from the lower arm. At this time, Switching
operation of the upper arm are permitted.
3.2 Precautions for protection operation
3.2.1 Over current (OC)
• If the over current continues for more than
t
dOC
, the IGBT is judged to be in OC state and is slowly
turned off. At the same time, an alarm signal is output.
• If the current drops below the over current protection level within the
t
dOC
period, the OC protection is
not activated and the IGBT is turned off normally.
• There is no alarm signal output function in the upper arm of P629 and P639, but the OC protection
works and the IGBT is turned off slowly.
