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Hi Ole, the circuit should only output a square wave signal to the mosfets to drive the transverter in push-pull mode. I want to find the sweetspot of the transformatos, I do not think that succeeds with sine and fixed frequency. Perhaps you can achieve a more effective operation and higher frequency with short pulses. what do the mentioned protection circuits look like? Overvoltage protection can indeed be produced via Zener diodes or suppressor diodes. I think the transverter will also receive energy spikes back to the drive coil through the ferroresonance that may be deadly to the mosfets. With ohmic load the circuits worked perfectly only with large transformers the Igbts went defective. Greetings Sven
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-------- Ursprüngliche Nachricht --------
Von: "[email protected] [EVGRAY]" <[email protected]>
Datum:27.06.2018 03:37 (GMT+01:00)
An: [email protected]
Betreff: [EVGRAY] Re: Push pull generator.
Hi Sven,
"So driver board and control board separately. At the low frequency, the interference should be limited by longer lines."
Long lines give more interference than short lines. The longer lines can have more area to be swept by ambient fields.
"Until now, I have always broken the mosfets with the drivers, I want to design the driver board so that this does not happen so easily."
Then some protection circuit is needed like in commercial products. The SG3525 has a shutdown input that can be used for shut down when an error is encountered. A current monitoring circuit and an over voltage monitoring circuit and perhaps a temperature sensing circuit could be used to shut down the MOSFETs before being destroyed.
As transformers have symmetrical Vs [Volt x second] product the input signal has to be symmetric if not used as just an isolated inductor. This is normally done by using a HF carrier wave that is PWM modulated with a sine wave. The carrier wave has to be perhaps of 10 to 20 times greater frequency than that of the modulation signal. If it is to be used as an inductor the PWM signal will work as step up or step down of the voltage or current.
Regards
Ole
---In [email protected], <s.friedrich@...> wrote :
Hi Guys,
since there is no response to this topic will write again.
Unfortunately, I have not found any suitable finished control boards and will now try again with a sg3525 controller to build a pulse width modulation in Pushpull principle.
I have already set up the circuit via a plug-in board with 2 potentiometers. from 5 to 40% pulse width and a frequency of 35 to 450 hertz. I think you can cover everything with this area, I think.
I want to build the controller modular so driver with optocoupler TLP250 for each mosfet, I do not want to use any IGBTs anymore as they are more sensitive.
So driver board and control board separately. At the low frequency, the interference should be limited by longer lines.
Until now, I have always broken the mosfets with the drivers, I want to design the driver board so that this does not happen so easily.
On Thamids blog, the TLP250 is described as used.
Best regards
Sven