Hi all,

I'm looking to pulse 900v dc through an IGBT. I have an optocoupler that controls a 15V pulse to the gate(600us 1.2 s period) but I'm having trouble seeing a signal past the emitter as nothing is getting through.
I've included a crude sketch to show whats going on.

Any input would be appreciated.

 

I would be using a Darlington pair on the Igbt base, as the opto-coupler won't have the power to force it on.

Have you got a better circuit, the load should be in the Collector side.?

 

Your gonna blow yourself up with that circuit!

At 4000 ohms on the devices emitter output its going to drive the whole 15 volt control system up to 900 volts when it tries to turn on.

The 4000 ohm load should be on the top collector side plus for a larger sized IGBT intended to work at high switching speeds a proper dedicated driver circuit or IC should be used

 

See

 

Hi guys,

Thanks for info. I would like to keep the optocoupler for isolation and the regulated 15V input does have over-voltage protection in case of a fault. So it would be best for the load to be before the IGBT?I have seen IGBT configurations with the high resistance loads on the emitter though. Don't worry, I'm using lower voltages to experiment.