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tex6202018-11-28 14:58:26
Electronics
tex620, 2018-11-28 14:58:26

How to solve the problem of draft in FULL-BRIDGE scheme?

I assembled the driver on the UCC-27425 circuit, I use the Titaev generator (500 kHz, meander 50%) as a master oscillator.
To check, I assembled one shoulder of the bridge, and put a voltmeter between the transistors to check if there is a draft.
It is)
Transistors IRFP-460
Signal transmission goes through GDT. A resistor (50 ohm) - Schottky diode (resistor-gate charging, diode-discharging) is connected to the gate through a pair.
Judging by the waveform, when transistor 2 opens, 1 should already be closed. However, there is still a draft)
Oscillogram from the gates of transistors relative to their sources:
B6TEy0y.jpg
I also tried to turn the duty cycle, the draft will disappear by 10-30 and 80-90%.
But the buildup will be uneven. I need a duty cycle close to 50%

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1 answer(s)
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A, 2018-12-06
@AndrBell

www.ti.com/document-viewer/UCC27425/datasheet/appl...bsvi.ru/raschet-i-primenenie-gdt
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Questions:
mmm ... in my opinion it’s so bad))) you need a low-resistance resistor and rectify it with a diode to another resistor, and here is a voltmeter.
A voltmeter with long wires should not be poked there at frequencies. (Albeit not gigahertz, but enough).
Is the oscillator at 1:10 worth it?
The oscillograms can be compared before and after the cascades - well, this is understandable
. The signal fronts, for example, are overwhelmed upwards - taking into account that the mikruha should easily master the frequency (I didn’t read the datasheet, but there we are talking about a dozen in nanoseconds of switching. Yes, and transients too. The frequency circuit copes with the GTD
?
If the duty cycle at the edges reduces the draft, then the transceiver, not having time to open, goes into constipation, vporos -->> can't you add a capacitance in parallel with a 50 Ohm resistor, more / less resistor?

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