Igbt Gate Drive Signals Test - Danfoss VLT Series Service Manual

5.2.9 IGBT Gate Drive Signals Test

This procedure tests the gate drive signals at the output of the
gate driver card just prior to them being delivered to the IGBT's.
A simple test to check for the presence of the gate signals
can be performed with a DVM, however to actually check the
waveforms an oscilloscope is required.
CAUTION
!
Disable DC bus when performing this test with
Test Cable p/n 176F8437. Failure to do so could
result in damage to drive if probe is inadvertently
connected to wrong pins. Additionally, AC mains
bus bars are in close proximity to these test
points. Exercise caution when working close to
high voltage components.
Prior to beginning the tests, ensure that power is removed
from the unit and that the DC Bus capacitors have been
discharged.
Check for the presence of DC bus voltage by measuring power
card connector MK105 (A) with respect to MK105 (B). The
voltage should be zero (0) before proceeding.
1. For D-frame size units, follow procedure in
Section 6 for soft charge card removal and
disengage soft charge card far enough to
disconnect cable plugged into MK3.
2. Disconnect cable from MK3 connector on soft
charge card and connect one end of test cable
into MK3.
pin 1
MK850
(brake)
MK105
(brake option)
MK250 MK350
MK450
MK102 (U)
Figure 5-13. Gate Drive Card Test Connectors
3. For D-frame size units, reinstall soft charge card.
4. Disconnect connectors MK100 and MK105 on
power card.
5. Connect free end of Test Cable into MK105.
6. Connect SCR gate shorting plug (included with
test cable 176F8437) into cable that was
removed from MK100.
Located on the gate drive card near each gate signal lead is a
3 pin test connector. These are labeled MK250, MK350,
MK450, MK550, MK650, MK750, and, if the drive is equipped
with a brake option, MK850.
For the sake of clarity, refer to the 3 pins as one, two, and
three, reading left to right. Pins 1 and 2 of each connector are
in parallel with the gate drive signal sent to the IGBTs. Pin 1 is
the signal and pin 2 is common.
7. Reconnect AC power to drive.
8. In stop mode, apply power to drive.
9. Measure pins 1 and 2 of each test connector.
Each reading should be approximately –9 VDC,
indicating all IGBTs are tuned off.
10. Apply run command to drive and 30 Hz reference.
MK650
MK550
MK103 (V)
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MK750
MK104 (W)
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