Re: AW: Re: Aw: Re: AW: Re: [EVGRAY] Re: Push pull generator.

Hi Sven,

The website is in German too: https://server.ibfriedrich.com/wiki/ibfwikide/index.php/Hauptseite https://server.ibfriedrich.com/wiki/ibfwikide/index.php/Hauptseite
The pages aren't built the same way as for the English part though.

The two figures 31a and 31b shows the difference in the wiring. In figure 31a the inductance of the source lead and an extra wire in series with the source leg shares the current of both the gate circuit as well as the load current. This induces voltages that are added (in series) to the gate driver voltage which make false signals on the gate.

The figures are cut and pasted from here: https://www.infineon.com/dgdl/an-937.pdf?fileId=5546d462533600a40153559ea1481181 https://www.infineon.com/dgdl/an-937.pdf?fileId=5546d462533600a40153559ea1481181

In figure 31b the gate current and load current is only shared by the source lead which makes the induced voltages less than that in figure 31a. Also observe where the decoupling capacitor is placed to make the smallest loop of the MOSFET and its load and minimum shared current of the gate circuit and load circuit.

Regards
Ole
 

---In [email protected], <s.friedrich@...> wrote :

 

 Hi Ole, I have removed the star-shaped lines and replaced them with a guide as shown in the picture. At each mosfet I twisted a source line with a gate line. I have removed the negative lead for Source because the connection to the MOSFET is there. Maybe I should omit the output lines to the driver's twisting. I can not open the website. Greetings Sven
 

 Von Samsung Mobile gesendet



-------- Ursprüngliche Nachricht --------
Von: "onielsen@... [EVGRAY]" 
Datum:08.07.2018 19:31 (GMT+01:00) 
An: [email protected] 
Betreff: Re: Aw: Re: AW: Re: [EVGRAY] Re: Push pull generator. 

   Hi Sven,

"... so pull each wire individually to the capacitor as a DC power source.
 
 I've twisted the wires but the problem occurs even before the drivers on the LED I've switched before start to flicker though, I've already removed the minus wires there to disconnect the switching area and the optical area minus it became better but not much."

 Hope it isn't the star connected wires that were twisted as they should be decoupled instead of coupled together. When twisted they share the magnetic field of the twisted segment. This acts like a transformer. The normal way of twisting is to make a transmission line where the energy is in between the forward conducting and the return wire of the energy carrying line.

The opto isolator is of high impedance and will have a hard job of driving a capacitive input with fast charging/discharging. Putting a capacitor in parallel with the one already in the MOSFET gate-source only slows down the signal.

When measuring with a high impedance oscilloscope probe on a low impedance circuit the loop of the ground wire also picks up magnetic changes. Thus minimize this loop during measurements by putting the ground wire close to the signal being measured. Else it will pick up additional induced voltage when changing magnetic fields pass by the loop.

Take a look at this page 'EMC Check' to get an idea: https://server.ibfriedrich.com/wiki/ibfwikien/index.php?title=EMC_Check https://server.ibfriedrich.com/wiki/ibfwikien/index.php?title=EMC_Check

Regards
Ole

 

---In [email protected], <s.friedrich@...> wrote :

 Hi Ole,
 
 I've rewired that to your specifications but now it's even worse and I've always thought you should wire a star, so pull each wire individually to the capacitor as a DC power source.
 
 I've twisted the wires but the problem occurs even before the drivers on the LED I've switched before start to flicker though, I've already removed the minus wires there to disconnect the switching area and the optical area minus it became better but not much.
 Of course I have to put together the minus of the high potential and the low potential somewhere else that does not work. I then made it central before the 15 volt voltage regulator.
 
 Something is lazy
 
 regards
 
 Sven

...

Got truncated again.

Hi Sven,

The website is in German too: https://server.ibfriedrich.com/wiki/ibfwikide/index.php/Hauptseite https://server.ibfriedrich.com/wiki/ibfwikide/index.php/Hauptseite
The pages aren't built the same way as for the English part though.

The two figures 31a and 31b shows the difference in the wiring. In figure 31a the inductance of the source lead and an extra wire in series with the source leg shares the current of both the gate circuit as well as the load current. This induces voltages that are added (in series) to the gate driver voltage which make false signals on the gate.

The figures are cut and pasted from here: https://www.infineon.com/dgdl/an-937.pdf?fileId=5546d462533600a40153559ea1481181 https://www.infineon.com/dgdl/an-937.pdf?fileId=5546d462533600a40153559ea1481181

In figure 31b the gate current and load current is only shared by the source lead which makes the induced voltages less than that in figure 31a. Also observe where the decoupling capacitor is placed to make the smallest loop of the MOSFET and its load and minimum shared current of the gate circuit and load circuit.

Regards
Ole

Hi Ole, I have removed the star-shaped lines and replaced them with a guide as shown in the picture. At each mosfet I twisted a source line with a gate line. I have removed the negative lead for Source because the connection to the MOSFET is there. Maybe I should omit the output lines to the driver's twisting. I can not open the website. Greetings Sven

Von Samsung Mobile gesendet

-------- Ursprüngliche Nachricht --------
Von: "[email protected] [EVGRAY]" <[email protected]> 
Datum:08.07.2018  19:31  (GMT+01:00) 
An: [email protected] 
Betreff: Re: Aw: Re: AW: Re:  [EVGRAY] Re: Push pull generator. 

Hi Sven,

"... so pull each wire individually to the capacitor as a DC power source.

I've twisted the wires but the problem occurs even before the drivers on the LED I've switched before start to flicker though, I've already removed the minus wires there to disconnect the switching area and the optical area minus it became better but not much."

Hope it isn't the star connected wires that were twisted as they should be decoupled instead of coupled together. When twisted they share the magnetic field of the twisted segment. This acts like a transformer. The normal way of twisting is to make a transmission line where the energy is in between the forward conducting and the return wire of the energy carrying line.

The opto isolator is of high impedance and will have a hard job of driving a capacitive input with fast charging/discharging. Putting a capacitor in parallel with the one already in the MOSFET gate-source only slows down the signal.

When measuring with a high impedance oscilloscope probe on a low impedance circuit the loop of the ground wire also picks up magnetic changes. Thus minimize this loop during measurements by putting the ground wire close to the signal being measured. Else it will pick up additional induced voltage when changing magnetic fields pass by the loop.

Take a look at this page 'EMC Check' to get an idea: https://server.ibfriedrich.com/wiki/ibfwikien/index.php?title=EMC_Check

Regards
Ole


---In [email protected], <s.friedrich@...> wrote :

Hi Ole,

I've rewired that to your specifications but now it's even worse and I've always thought you should wire a star, so pull each wire individually to the capacitor as a DC power source.

I've twisted the wires but the problem occurs even before the drivers on the LED I've switched before start to flicker though, I've already removed the minus wires there to disconnect the switching area and the optical area minus it became better but not much.
Of course I have to put together the minus of the high potential and the low potential somewhere else that does not work. I then made it central before the 15 volt voltage regulator.

Something is lazy

regards

Sven

...