PC
BOARDS
Service Manual M4 - M10
22.10.2001
Page
88
9.2.4 Schematic diagrams
NOTE! Schematic diagrams are not distributed to Service Centres. In case of
schematic diagrams are needed these can be requested from Producer.
9.2.5 Troubleshooting
Troubleshooting of the Power board will be carried out by checking signals
and supply voltages generated on the board. The signals and voltages will be
measured from terminals on the board, which procedure is comprehensive
enough to determine operation of the circuitry. Signals and voltages are
described on the layout drawings of the particular boards.
9.2.6 Gate circuitry
9.2.6.1 Description
Gate circuitry consists pulse amplifier to amplify logic level 0 - 5V pulses to
+/-15V pulses for gates of IGBTs in inverter section. While the gate amplifier is
feeding pulses in regulated levels, charging time of gate junction (can be
considered as a capacitor) is controlled by gate resistors according to rating
of the IGBT in particularly rated drive. Proper control for IGBTs are required
to achieve lowest possible internal losses, such as switching losses and on
state losses in silicon ship, without risking cut off capacity in case of
exceeding collector current.
9.2.6.2 Settings of gate resistors
The gate resistors are located on the Power board. Resistance values of the
resistors are specified on charts GATE.XLS, CX2GATE.XLS and CX6GATE.XLS
for various types of IGBTs used in units. The charts above can be found in
section 17.
For physical location of the resistor on the Power boards, look at layout
drawings in section 9.2.3 and the next figure.
