SJ700
2
Inverter
T
roub
leshooting
and Maintenance
6–27
IGBT Test Method
The following procedure will check the power module, including inverter transistors (IGBTs),
IPM, diodes, and thyrister until replacement of inverter (1,000,000 start/stop cycles):
1.
Disconnect input power to terminals [R, S, and T] and motor terminals [U, V, and W].
2.
Disconnect any wires from terminals [P] and [RB] for regenerative braking.
3.
Use a Digital Volt Meter (DVM) and set it for 1 ohm resistance range. You can check the
status of the charging state of terminals [R, S, T, U, V, W, RB, P, and N] of the inverter and
the probe of the DVM by measuring the charging state.
Almost infinite ohms = “non-conducting,” and 0 to 10 ohms = “conducting.”
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 [P] and [N] with the DC current range, confirm
that the smoothing capacitor is discharged fully, then execute the tests.
Circuit Type
DVM Probe
Measured Value
+
–
Converter
D1
R
PD
Non-conducting
PD
R
Conducting
D2
S
PD
Non-conducting
PD
S
Conducting
D3
T
PD
Non-conducting
PD
T
Conducting
D4
R
N
Conducting
N
R
Non-conducting
D5
S
N
Conducting
N
S
Non-conducting
D6
T
N
Conducting
N
T
Non-conducting
Inverter
TR1
U
P
Non-conducting
P
U
Conducting
TR2
V
P
Non-conducting
P
V
Conducting
TR3
W
P
Non-conducting
P
W
Conducting
TR4
U
N
Conducting
N
U
Non-conducting
TR5
V
N
Conduct
N
V
Non-conducting
TR6
W
N
Conducting
N
W
Non-conducting
R
S
T
D1
D2
D3
D4
D5
D6
U
V
W
TR1
TR2
TR3
TR4
TR5
TR6
PD
P RB
C
TR7
+
Converter
Inverter
N
