Will the bleed resistors enable a shorter path to ground or not?

  • Thread starter Thread starter checkmatescott
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The discussion revolves around building an H-bridge using two P-channel and two N-channel MOSFETs to create an alternating current (AC) output from a 55V DC source. Key concerns include ensuring that the gate-source voltage (Vgs) remains below the rated limits to protect the MOSFETs, with suggestions for using voltage dividers and Zener diodes for this purpose. Participants emphasize the importance of preventing simultaneous conduction of the N-channel and P-channel MOSFETs to avoid shoot-through currents, recommending the use of dead time in the switching logic. There are also recommendations to study commercial designs and control chips for better understanding and implementation. The complexity of creating a reliable AC inverter circuit is acknowledged, with advice to learn foundational concepts before attempting advanced designs.
  • #61
checkmatescott said:
is there any software that you can recommend so that I might be able to simulate what I'm trying to do?
LTSpice
 
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  • #62
ok I have spice, does it have IC's integrated in/with the software?
 
  • #63
checkmatescott said:
to be honest I kind of need spoon feeding a little bit to get me through this next part of my project
why skeptical?
 
  • #65
anyway that software is EPIC, I can't thank you enough
 
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  • #66
checkmatescott said:
ok I have spice, does it have IC's integrated in/with the software?
Read the online instructions. Less typing, more study. In our service/support department the favorite acronym was RTFM; which BTW, you would never say to a customer.

But, yes some. IC manufacturers will often give you spice models. But that only works for people that can search the web and find answers themselves.
 
  • #68
Do not trust a simple schematic unless you know the credentials of who did it. When there are specs like max 60V ask why and get component specs and examine the interface. Trustworthy designs come from TI, Analog Deices, Microchip, Hitachi, Toshiba, etc. This is just a rookie undergraduate example. Using DO NOT EXCEED (DNE) levels is not a good design practice. Use the values in the tables where it is guaranteed. U1 is DNE 22V This also would exceed Vgs(max).
1689024693339.png

If this is your 1st attempt , it is impossible to design anything and have it work without failure and it will cost much more than buying one. But you may learn tools in the process. I recommend fast learners buy one then analyze it for load impedance ratio error and noise. Then learn how that works. It's simple resistor divider Ohms Law. The voltage drop load regulation error is the same % ratio of impedances for small values. Obviously 50% drop they are equal 1:1
 
  • #69
Ok I think I understand that, so which should I choose ir2103 or lt1160 in your opinion? are there any books that you recommend for learning?
 
  • #70
so the vgs of the P-channel mosfets cannot go above -20v and and the chips are rated for 18v so must not exceed that.
 
  • #71
I need to choose the N-channel mosfets, how do I do this correctly?
 
  • #72
so these are the N chan fets that i have settled on

IRFP4668​

I am still unclear how to make "The two halves a whole" or how to wire it up. As far as I can work out, the N chan fets are used as high side switches. The drain is connected to the supply voltage in my case it will be 55v and source to load. The gate needs the correct vgs to turn it on then I was looking at direct drive, level shifted drive, or bootstrap gate drive. In the picture you provided its a bootstrap driver and I suppose the logic in pins are important can I please have some guidance. Thanks again!
1689096141292.png
 
  • #73
can you teach me how to use google effciently for example when you search that initial image and cross checked with the internet?
 
  • #74
what is personal speculation
 
  • #75
can you draw me a diagram of where and how to place components to at least give me a clue, in the form of a very rough schematic plase
 
  • #76
so I've RTFM and i would like a walkthrough of how it works an explaination or description, push in the right direction, without degree level knowledge. Treat me as a layman can anyone shed some light!
 

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  • #77
checkmatescott said:
can you teach me how to use google effciently for example when you search that initial image and cross checked with the internet?
Probably not.
 
  • #78
ok what, is it like this?
 

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  • #79
logging off for the night, my eyes are gone cyas
 
  • #80
Thread is on "pause" for a bit...
 
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  • #81
berkeman said:
Thread is on "pause" for a bit...
Whelp, it turns out that this newbie is an accomplished hacker of a number of things, and proud of it. He is now gone, and this thread will remain closed. Sorry that you spent so much time trying to help this "Help Vampire", but his intentions were not good. Thanks folks.
 
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