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Maintenance and Inspection Section 6-4
6-4-3 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 Ω 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.
Table Legend
Almost infinite resistance: ≅hΩ Almost zero resistance: ≅0Ω
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.
Part DVM Measured
Value
Part DVM Measured
Value
Part DVM Measured
Value
–+ –+ – +
D1 [R] [+1] ≅hΩ D5 [S] [–] ≅0Ω TR4 [U] [–] ≅0Ω
[+1] [R] ≅0Ω [–] [S] ≅hΩ [–] [U] ≅hΩ
D2 [S] [+1] ≅hΩ D6 [T] [–] ≅0Ω TR5 [V] [–] ≅0Ω
[+1] [S] ≅0Ω [–] [T] ≅hΩ [–] [V] ≅hΩ
D3 [T] [+1] ≅hΩ TR1 [U] [+] ≅hΩ TR6 [W] [–] ≅0Ω
[+1] [T] ≅0Ω [+] [U] ≅0Ω [–] [W] ≅hΩ
D4 [R] [–] ≅0Ω TR2 [V] [+] ≅hΩ TR7 [RB] [+] ≅hΩ
[–] [R] ≅hΩ [+] [V] ≅0Ω [+] [RB] ≅0Ω
TR3 [W] [+] ≅hΩ [RB] [–] ≅hΩ
[+] [W] ≅0Ω [–] [RB] ≅hΩ
D1
[R/L1]
D2 D3
D4 D5 D6
[PD/+1]
[P/+] [RB]
TR1 TR2 TR3
TR4 TR5 TR6 TR7
[U/T1]
+
[N/ - ]
[S/L2]
[T/L3]
[V/T2]
[W/T3]
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