[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: [TCML] DRSSTC weird waveform behavior



I'm sure my capacitors are fine, they are rather huge.  The reason im sure, its doing this, is because of my isolation transformer.  I wanted to scope the bridge output, without damaging it due to the common Black clip on my scope.  So I used an isolation transformer on the mains input.  I didnt have one. So i used the most cheapest source, with lost of lost.  A microwave transformer.  I stacked two together so the cores made contact, and tied the secondary wire, so I have a 1:1 transformer.  Does the trick, but im sure thats the reason for the dips...Bad transformer.  I'd imagen those things to become flat when I rehook it to mains feed.  Will do the 2-prob ADD function for that later after I get my phase right.  Which, im currently struggling with.  I tried an inductor with variable 1-100,000ohm resistor (15 turns) and i had the resistor in parallel with the inductor.  This was in series, with the CT leg that goes to the board, the input side, not the ground side.  Didnt change anything at all really. even turning the resistor, really did nothing.  unless im doing something wrong, I plan to try inductor--resistor in series, and parallel the whole thing to the CT.

> Date: Sat, 2 Jul 2011 08:02:31 -0700
> From: cn@xxxxx
> To: tesla@xxxxxxxxxx
> Subject: Re: [TCML] DRSSTC weird waveform behavior
> 
> It may be also that if there is no dead time between phases the top 
> devices will turn on for a split microsecond before the bottom ones turn 
> off, leading to a large current spike (known as shoot-through).  A 
> half-uS of dead time or so will take care of this.  It also appears that 
> there may not be adequate power supply bypassing--you need a big honkin' 
> cap to feed the bridge.  The gate drive should have only enough 
> resistance to avoid oscillation in the gate waveform, normally less than 
> an ohm.  Even more important is to minimize the gate drive inductance, 
> which means VERY short and wide leads from the driver to the gate.
> 
> ---Crl
> 
> 
> 
> 
> 
> 
> 
> 
> __________ Information from ESET NOD32 Antivirus, version of virus signature database 6258 (20110701) __________
> 
> The message was checked by ESET NOD32 Antivirus.
> 
> http://www.eset.com
> 
> 
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
 		 	   		  _______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla