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MicroHarmony Cell Sizes 40 - 260A Manual
Gate Clamp Board
CHAPTER
6
Gate Clamp Board
The gate clamp board protects the IGBT from over voltage transients. "Personality" gate resistors and capacitors are
installed on this board as well; they are specific to the IGBT used. The board also acts as a terminal block for
paralleling IGBT modules with a common gate drive. The board is designed to be installed directly to 62mm dual
IGBT modules. This reduces lead lengths to minimize noise and stray inductance.
A gate clamp circuit is installed across each IGBT. In the event of an over voltage condition across any IGBT, the bi-
directional transient voltage suppressor network turns on and provides enough gate current to partially turn the IGBT
on. This reduces the voltage stress across the device.
6
A 1550V nominal voltage turn on threshold is generated by connecting four transorbs in series; one 350V and three
400V devices, from collector to gate. An 18V transorb is connected from gate to emitter to protect the IGBT from
short circuit by clamping the gate to emitter voltage to 18V.
The transorb devices are intended for intermittent operation during out-of-saturation turn off where peak voltages can
exceed the 1700V device rating.
A gate resistor and gate emitter capacitor can be installed on this board, with options for through-hole or surface
mount components. If the resistor is not required, a zero ohm resistor or jumper must be installed to allow for proper
gate drive operation. If the capacitor is not required, it can be omitted.
The gate resistor conducts during the on and off switching pulses. This resistor serves two main purposes:
supplement the cell control board's turn on and turn off resistors to reduce the number of cell control board part
number variations, and decouple parallel IGBTs from a common gate drive.
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19001467: Version 1.0
6-1
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