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IGBT not switching in H Bridge. Is it a driver problem?


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This driver circuit is working perfectly fine in my other designs
If you say the design is perfectly fine then the problem is your wiring, or bad parts, or....... So you need to trouble shoot. Do you need help with that?

"We" can not tell if it is bad design or bad pinout, or soldering, because it is hard to get information from you.

Every semester university students from India post that they can't make a H bridge work. This is a common problem. Most of the time they don't understand top side gate drives. It takes 15 to 30 posts before we can get a schematic. Then the bread board does not equal the schematic. The parts are not what is on the schematic. The scope traces are not labeled. It is common to have the top and bottom transistors on at the same time. Often the schematic is copied from a non working internet design. Even the best schematic will have wires that go off the page with no label.

Because the design is perfectly fine then: Open up "+Bus325". (remover power) Now show the G-S voltage of the top transistor. (scope)

Are all four "Drivers" the same?

There is a professor that requires his class to make a H bridge with out giving the students the information they need. "Apply a voltage to the Gate and the transistor turns on." This mostly works for the bottom transistors but does not work for the top transistors. The professor should teach the voltage needs to be applies from G to S (G to E). Sorry if I assumed your are in this class. Many posts that start out with "bridge won't work. why? no-schematic" are from a university.
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