Author Topic: CW coil with terrible gate waves. Need help  (Read 1089 times)

Offline Acid Byte

  • High Voltage Enthusiast
  • *
  • Posts: 27
  • Karma: +0/-0
    • View Profile
CW coil with terrible gate waves. Need help
« on: March 04, 2019, 09:02:50 PM »
Hello!

I am running a cw coil, but running into wild issues on the gate.

So here is my gate drive without running the coil.


But when i turn the power open this starts to happen.


Im running a sstc5 circuit but with ud2.5 gatedrive.
The fet switches are fdl100n50
Im running the coil at approx 260khz
Im currently using 18v gate protection and apply just under 18 volts of gate wave.
Using 6.2 ohms gate resistors with the parallel diode.
My gdt is n30 material and has a 6:4 turn ratio

Have anyone seen this in their builds?
And what might be the cause of this?
I can run the coil at 1kw from mains for 30 seconds with only about 3 to 4 degree change in heat on the bridge.
But somehow im thinking this left over heat is cause by this weird stuff going on.

Greetings jeroen
« Last Edit: March 04, 2019, 09:12:55 PM by Acid Byte »

Offline T3sl4co1l

  • High Voltage Technician
  • ***
  • Posts: 122
  • Karma: +9/-0
    • View Profile
Re: CW coil with terrible gate waves. Need help
« Reply #1 on: March 06, 2019, 04:02:28 AM »
I don't know that that's bad, or an issue.  With all the noise around, I would easily expect to see that from probe effects alone.

Can you show the probe connection?

Tim

Offline Acid Byte

  • High Voltage Enthusiast
  • *
  • Posts: 27
  • Karma: +0/-0
    • View Profile
Re: CW coil with terrible gate waves. Need help
« Reply #2 on: March 06, 2019, 06:51:39 AM »
Hey tim!
Thanks for responding.
Yeah i can make some pictures after work.
But telling you im measuring the gatewave directly from gate to source with a floating scope ground.

I tried increasing the Rg which took away some heat too.
Lowside gate is running a nice waveform.
Though the highside is looking damped.
Is this normal?

Another shot here with a little less ringing then before with increased Rg


Greeting jeroen

Offline Mads Barnkob

  • Administrator
  • High Voltage Expert
  • *****
  • Posts: 1323
  • Karma: +21/-0
  • Denmark
    • View Profile
    • Kaizer Power Electronics
Re: CW coil with terrible gate waves. Need help
« Reply #3 on: March 06, 2019, 07:40:06 AM »
But telling you im measuring the gatewave directly from gate to source with a floating scope ground.

A floating ground is the reason for the excessive noise, you either have to isolate your mains supply and ground the negative rails to use the ground clip or invest in a differential probe.

You have a perfect switching gate waveform, so that is properly also true when driving the coil :)
http://www.kaizerpowerelectronics.dk - Tesla coils, high voltage, pulse power, audio and general electronics

Offline Teravolt

  • High Voltage Technician
  • ***
  • Posts: 104
  • Karma: +2/-0
    • View Profile
Re: CW coil with terrible gate waves. Need help
« Reply #4 on: March 06, 2019, 03:13:57 PM »
does your mosfet transitioning have any dead time. if your bridge fets are turning on at any time together you can see that type of noise. usaly the UD drivers dont utalize it. if this is happening you will have suring on your line. if you add a lamp in series with your line you might be able to see this. if it were me I would float your mains and earth ground the center tap of your caps if you are using a dublier temoraraly so you can tie your scope to a common at earth ground. usuing a ground lifter adaptor or floteing your scope could be asking for truble.

Offline Acid Byte

  • High Voltage Enthusiast
  • *
  • Posts: 27
  • Karma: +0/-0
    • View Profile
Re: CW coil with terrible gate waves. Need help
« Reply #5 on: March 06, 2019, 07:05:55 PM »
Thank you all for your response!

A floating ground is the reason for the excessive noise,

So you think its sort of like "regauging" on the switching transistion?
Wich acts out as noise on the scope.

So i did some testing and went upto 17 ohms on the gate. The heat seemed to be less on the bridge.
Also radiate rf was much stronger as the television down stairs didnt like it so much(this was a first for this coil)
Also the switching noise was allot less. Cant it be like cross conduction?
The noise is also there measuring current through ct.


Actually yes i have to buy a mains isolation transformer. But moneys a little tight at the moment.
Then again so far my floating scope hasnt failed on me yet.
I know its not the most ideaal situation. But for now allows me to scope output waves and high side gates.

Heres a picture of the output waveform.


Greetings jeroen
« Last Edit: March 06, 2019, 09:07:14 PM by Acid Byte »

High Voltage Forum

Re: CW coil with terrible gate waves. Need help
« Reply #5 on: March 06, 2019, 07:05:55 PM »

 


* Recent Topics and Posts

post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
davekni
Today at 08:20:25 PM
post Re: (DR)SSTC music MIDI files
[Dual Resonant Solid State Tesla coils (DRSSTC)]
DJthefirst
Today at 08:20:07 PM
post Re: Power MOSFETs with fast recovery body diodes
[Electronic Circuits]
davekni
Today at 08:09:29 PM
post Re: A few (stupidly basic) questions
[Beginners]
Mads Barnkob
Today at 02:53:24 PM
post Re: A few (stupidly basic) questions
[Beginners]
John123
Today at 11:46:07 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
Today at 11:40:55 AM
post Re: Power MOSFETs with fast recovery body diodes
[Electronic Circuits]
John123
Today at 11:32:19 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
Today at 03:48:55 AM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
ZakW
April 01, 2020, 09:47:42 PM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 01, 2020, 09:31:49 PM
post Re: Power MOSFETs with fast recovery body diodes
[Electronic Circuits]
davekni
April 01, 2020, 08:47:11 PM
post Re: Fishing for atmospheric electricity
[Static Electricity]
johnf
April 01, 2020, 08:45:14 PM
post Re: Homemade HV transformer
[Transformer (Ferrite Core)]
johnf
April 01, 2020, 08:37:29 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
davekni
April 01, 2020, 08:24:06 PM
post Re: Pt100 oddities
[Electronic Circuits]
davekni
April 01, 2020, 08:16:59 PM
post Re: Pt100 oddities
[Electronic Circuits]
johnf
April 01, 2020, 07:50:16 PM
post Re: Fishing for atmospheric electricity
[Static Electricity]
haversin
April 01, 2020, 07:42:47 PM
post Re: Homemade HV transformer
[Transformer (Ferrite Core)]
John123
April 01, 2020, 07:39:48 PM
post Re: Fishing for atmospheric electricity
[Static Electricity]
John123
April 01, 2020, 06:07:44 PM
post Photographing/filming high voltage arcs
[DSLR]
John123
April 01, 2020, 05:17:04 PM
post Power MOSFETs with fast recovery body diodes
[Electronic Circuits]
John123
April 01, 2020, 02:01:30 PM
post Re: Pt100 oddities
[Electronic Circuits]
kamelryttarn
April 01, 2020, 01:38:47 PM
post Re: Pt100 oddities
[Electronic Circuits]
T3sl4co1l
April 01, 2020, 12:49:21 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
April 01, 2020, 10:29:06 AM
post Pt100 oddities
[Electronic Circuits]
kamelryttarn
April 01, 2020, 09:48:37 AM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
Weston
April 01, 2020, 07:01:51 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
April 01, 2020, 04:15:41 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 01, 2020, 04:05:20 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
April 01, 2020, 01:51:05 AM
post Re: A few (stupidly basic) questions
[Beginners]
davekni
April 01, 2020, 01:32:54 AM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
ZakW
March 31, 2020, 11:03:36 PM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
Weston
March 31, 2020, 10:13:13 PM
post Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
ZakW
March 31, 2020, 09:15:23 PM
post Re: Homemade HV transformer
[Transformer (Ferrite Core)]
AlexanderHun
March 31, 2020, 12:05:40 PM
post Re: A few (stupidly basic) questions
[Beginners]
Mads Barnkob
March 31, 2020, 08:54:35 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 31, 2020, 04:58:16 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
davekni
March 31, 2020, 04:44:05 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
March 31, 2020, 01:33:16 AM
post Fishing for atmospheric electricity
[Static Electricity]
haversin
March 31, 2020, 12:48:56 AM
post Re: Corona lockdown thread, tell about your situation
[General Chat]
Mads Barnkob
March 30, 2020, 08:08:54 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
March 30, 2020, 07:20:08 PM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 30, 2020, 06:46:02 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
davekni
March 30, 2020, 06:35:13 PM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 30, 2020, 05:00:11 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
March 30, 2020, 04:30:55 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
SteveN87
March 30, 2020, 01:16:47 PM
post Re: Conical pulse skip DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Acid Byte
March 30, 2020, 07:23:21 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
March 30, 2020, 06:13:52 AM
post Re: A few (stupidly basic) questions
[Beginners]
MRMILSTAR
March 30, 2020, 05:31:27 AM
post Re: synchronous motors up for bid
[General Chat]
klugesmith
March 30, 2020, 02:55:41 AM

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 
SimplePortal 2.3.6 © 2008-2014, SimplePortal