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Registered Member #4465
Joined: Wed Apr 18 2012, 08:37AM
Location: Bucharest, Romania
Posts: 145
Up to 450V? Maybe that’s too much for such circuit. There occurs an overlapping conduction of both transistors because there’s no dead time between the upper and lower transistor.
Registered Member #4992
Joined: Wed May 23 2012, 03:57PM
Location:
Posts: 108
Cross conduction, that's what I thought. What to do? Do I need a new drive circuit and if so what would be a very efficient driver for high voltageses? Because I have 240v and mains.
Registered Member #4992
Joined: Wed May 23 2012, 03:57PM
Location:
Posts: 108
So I took out the tc drivers and added a ir2113 mosfet driver which is suppose to be dv/dt immune as they say. Stil I'm burning switches. As can be seen on the picture I stil have little cross conducting on the mosfets. I already have 15ohm resistors in series. What should I do to get a pure square wave?
Registered Member #4465
Joined: Wed Apr 18 2012, 08:37AM
Location: Bucharest, Romania
Posts: 145
You need to implement some sort of dead-time in that circuit. I think originally the zener diodes were used there for this job. Also see the discussion here:
Registered Member #4992
Joined: Wed May 23 2012, 03:57PM
Location:
Posts: 108
I do have the zeners on and the dead time is ok and I also have a very clean signal. My problem is the short that my probe is having. When I try to ground my scopes probe it starts heating up my resistor and on the probe until the main power trips. I loosened everything and checked all the connections. It seems that my probe ground makes a dead short to my variac even if the Mosfets are not turned on and also with the mosfets disconnected.
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
furnace wrote ...
My problem is the short that my probe is having. When I try to ground my scopes probe it starts heating up my resistor and on the probe until the main power trips. I loosened everything and checked all the connections. It seems that my probe ground makes a dead short to my variac even if the Mosfets are not turned on and also with the mosfets disconnected.
This is what is supposed to happen when you ground something that is not ground. The fuse is supposed to blow for safety reasons.
You have not given any schematics that explain what you do so not much to say except you need to learn the simple things before you try to do build something complicated and dangerous.
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Voltage rise on gate
