DG-IRMCK203 Datasheet, PDF (15/67 Pages) International Rectifier – Application Developer’s Guide

IRMCK203 Application Developer’s Guide
2.6.1 Gatekill Structure and Overcurrent/Overtemperature Fault
For example, the IRMCS2031 design platform for IRMCK203 has an advanced intelligent power module
(IRAMX16UP60A) rated at a 600V/16A. This IGBT module contains an integrated high voltage gate drive IC
(IR2136) with a thermistor.
A ground fault protection circuit is also equipped on the IRMCS2031. The signal is fed to an opto-coupler device to
trigger the signal to IRMCK203 pin 37, GATEKILL.
When an overcurrent condition occurs, GATEKILL is asserted and momentarily latched within the IR2136 for the
programmed period, which is approximately 9 milliseconds. After this period, the pending fault is automatically
cleared. Meanwhile, the triggered GATEKILL assertion latches and inhibits all PWM output gate signals off the
IRMCK203 until the user initiates a FAULT CLEAR action.
IRMCK203
GATEKILL
PWM Output
6
DC bus(+)
Opto
Ground
Fault
protection
Opto
INPUT
DC bus(-)
IRAMX16UP60A
overtemp
IR2136
RCIN
To
Motor
Figure 6. Protection Circuit Block Diagram
Figure 6 shows the protection circuit diagram. The IGBT module contains an RC circuit connected to RCIN input of
the IR2136, which automatically initiates FAULT CLEAR in 9 milliseconds after assertion of FAULT. The IGBT
module also contains an overtemperature protection circuit, which shuts down all IGBTs and performs automatic
FAULT CLEAR as well. Overtemperature protection can be enabled by adding a 6.8 kOhm external resistor. The
threshold level is set at approximately 110°C. The IRMCS2031 contains the ground fault protection circuit on the
high side DC bus (+) node. The circuit senses positive ground fault current and sends a trigger signal to GATEKILL
via a wired-OR FAULT signal.
Once any fault condition is detected, the IR2136 inside of the IGBT module momentarily latches the condition and
initiates FAULT output and shutdown of all six IGBTs. Upon receiving the FAULT signal at its GATEKILL input,
the IRMCK203 disables all PWM gate signals and latches GATEKILL. It also disables PWM output.
To reset a fault condition, first write a “1” to the "FltClr" bit of the Fault Control register (see Section 4.2.6). This
clears the fault in the IRMCK203. Then write a “0” to the FltClr bit to re-enable fault processing. Note that PWM
output does not automatically restart after a fault condition is cleared.
2.6.2 DC Bus Faults and DC Bus Braking
The DC bus signal is employed for dc bus overvoltage, undervoltage protection and Brake control. It is also used
for compensation of motor controller scaling internal to the IRMCK203.
It is crucial to design a suitable dc bus feedback scaling for proper drive protection. The dc bus voltage can be
acquired via the ADS7818 A/D converter. The input of ADS7818 maps 0 - 5 Volts into 0 - 4095 digital counts.
The overvoltage and undervoltage trip levels are given in Table 9. The analog scaling (amplifier gain) of the dc
bus is restricted by the desired voltage trip levels. Therefore, the signal conditioning (amplifier gain) of dc bus
voltage feedback needs to be considered carefully.
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