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IGBT Test Method
The following procedure will check the inverter transistors (IGBTs) and diodes:
1
. Disconnect input power to terminals [R, S, and T] and motor terminals [U, V, and W].
2
. Disconnect any wires from terminals [+] and [–] for regenerative braking.
3
. Use a Digital Volt Meter (DVM) and set it for 1 resistance range. You can check the
status of the charging state of terminals [R, S, T, U, V, W, +, and –] of the inverter
and the probe of the DVM by measuring the charging state.
T
able Legend Almost infinite resistance: # Almost zero resistance: # 0
DVM DVM DVMPart
+ –
Measured
Value
Part
+ –
Measured
Value
Part
+ –
Measured
Value
[R][+1]
#
[S][–]
# 0
[W][+]
#
D1
[+1][R]
# 0
D5
[
–
][S]
#
TR3
[+][W]
# 0
[S][+1]
#
[T][–]
# 0
[U][–]
# 0
D2
[+1][S]
# 0
D6
[
–
][T]
#
TR4
[
–
][U]
#
[T][+1]
#
[U][+]
#
[V][–]
# 0
D3
[+1][T]
# 0
TR1
[+][U]
# 0
TR5
[
–
][V]
#
[R][–]
# 0
[V][+]
#
[W][–]
# 0
D4
[
–
][R]
#
TR2
[+][V]
# 0
TR6
[
–
][W]
#
NOTE: The resistance values for the diodes or the transistors will not be exactly the
same, but they will be close. If you find a significance difference, a problem may exist.
NOTE: Before measuring the voltage between [+] and [–] with the DC current range,
confirm that the smoothing capacitor is discharged fully, then execute the tests.
615
Troubleshooting and
Maintenance
6 15
Troubleshooting and
Maintenance