Charging/discharging a capacitor under uC control.

Thread Starter

Peter McLeod

Joined Jul 3, 2020
3
I would be most grateful if you could comment on the following. The attached is a circuit to charge or discharge a capacitor via a 120R resistor. The capacitor is then discharged through a low resistance route not included in the diagram.
There are three IGBT's in the circuit the charge and discharge are medium current and the 2nd discharge IGBT is a higher current to take the short circuit rush.
What concerns me is how to drive the devices. I have included TLP127 photoisolators but I am wondering about the grounding.
Could anyone comment.
 

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Thread Starter

Peter McLeod

Joined Jul 3, 2020
3
Many thanks for your replies. The low resistance circuit is as MrSalts realized a short circuit and it is a spot welder (partly) The voltages for spot welders can be as high as 600V (I have designed and sold these for many years) Only recently have I been looking into uP control. Hence my questions. In this instance the capacitors amount to 40,000uF and the charge voltage set at anything between 10 and 50V. The items welded are varied and the contact resistance can sometimes be high.
What I am concerned about before committing the circuit to PCB, is the grounding of each individual IGBT and have I avoided any problems using the photoisolators?
Thanks to ScottWang for your GIF help. I will keep this in mind.
 
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