Author Topic: Maximum switching speed estimation  (Read 170 times)

Offline TMaxElectronics

  • High Voltage Engineer
  • ****
  • Posts: 223
  • Karma: +14/-0
    • View Profile
    • My random (and very empty) electronics blog
Maximum switching speed estimation
« on: November 17, 2021, 12:31:51 AM »
So I finally had some time to look into the speeds of the IGBT bricks I have around (SKM300GB126DH2) so I can estimate the maximum switching frequency if I was to build a coil with them. I've been reading mads's page on the topic (https://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/igbts/) but the formulas given seem to give me erroneous values even at very low primary currents (something like 5kHz fmax2 at 50A). So my question is what have I been doing wrong? The values I used are 1:1 identical with those given in the datasheet.

It also seems to me like there might be an error in the last formula (the one for Fmax2). Doesn't it assume CW switching? It takes into account that conduction losses only occour during the on time, but not the switching losses ???
Add to that the fact that the die's thermal capacitance would allow for higher momentary power dissipation during the OT, than it would during CW operation. Calculating the thermal capacitance from that would probably be too much work, so I'm wondering if it might be a reasonable enough approximation to create an equivalent thermal impedance, that indicates the maximum temperature seen during a pulse in relation to the peak power. Kind of like this:

That would assume that the maximum die temperature is Tavg+Tpeak (average temperature + temperature rise during the pulse), ignoring the temperature drop below Tavg at the end of the offtime. That would be a slight overestimation and thus include a safety margin.

I also think it might be a good approximation of switching losses at lower currents to linearly scale them back with the ration between switching current and the current at which the losses given in the datasheet are specified.

When combining those two modifications to the formulas, I get a much more reasonable approximation of maximum switching frequency. At least they are more sensible when comparing the theoretical results with actual results I get for power dissipation in my large coil with SKM400 IGBTs.

So with the IGBTs I have I could go to 100kHz at 10% dutycycle, assuming 200us ontime, 800A Ip_peak and 50°C heatsink / 90° peak die temp. Does that sound reasonable?

Offline Uspring

  • High Voltage Engineer
  • ****
  • Posts: 258
  • Karma: +20/-0
  • Physicist
    • View Profile
Re: Maximum switching speed estimation
« Reply #1 on: November 18, 2021, 07:48:12 PM »
I think Mads equation for Fmax2 is ok. One has to observe though, that

a) the transistor is on only half of the time during the burst. That concerns Pcond.

b) the transient thermal impedance is used for RthetaJC.


Offline Mads Barnkob

  • Administrator
  • High Voltage Expert
  • *****
  • Posts: 1852
  • Karma: +49/-0
  • Denmark
    • View Profile
    • Kaizer Power Electronics
Re: Maximum switching speed estimation
« Reply #2 on: November 18, 2021, 08:24:13 PM »

It is like being forced to look at your old code, looking at a page like that... having to read it all again... AND understand my own train of thought at the time :) You can quickly get me in doubt ;)

Could you please provide the extrapolated numbers for your SKM300, that results in that very low Fmax2 estimation. Something must be off.

The article is one long assumption and derating of losses according to those assumptions. Its not a theoretical master piece, my math skills are simply not good enough for that, but its my best bet of a how-to-only-abuse-a-igbt-brick-just-enough-to-live-as-long-as-you-find-your-tesla-coil-interesting 8)


I think Mads equation for Fmax2 is ok. One has to observe though, that

a) the transistor is on only half of the time during the burst. That concerns Pcond.

b) the transient thermal impedance is used for RthetaJC.

I did not even include the difference between half-bridge and full-bridge. So the article for now really is only true for the half-bridge. But just before calculating the Pcond losses, its the halving of the previously 1/4'ing of a factor of faster soft switching that could be factor 2-10. So its all really +/- 3dB to be honest :)
https://kaizerpowerelectronics.dk - Tesla coils, high voltage, pulse power, audio and general electronics
https://www.youtube.com/KaizerPowerElectronicsDk60/join - Please consider supporting the forum, websites and youtube channel!

High Voltage Forum

Re: Maximum switching speed estimation
« Reply #2 on: November 18, 2021, 08:24:13 PM »

 


* Recent Topics and Posts

post Re: help with finding resonant frequency
[Beginners]
HVuser
Today at 04:43:39 AM
post Re: Looking to build by first DRSSTC as a high voltage beginner
[Dual Resonant Solid State Tesla coils (DRSSTC)]
futurist
Today at 01:37:46 AM
post Re: Practical limitations in size for Marx or CW
[Voltage Multipliers]
abstruse1
December 02, 2021, 11:35:39 PM
post Re: Practical limitations in size for Marx or CW
[Voltage Multipliers]
MRMILSTAR
December 02, 2021, 09:53:13 PM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
December 02, 2021, 05:10:30 AM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
December 02, 2021, 04:58:53 AM
post Re: Syntherrupter - A Feature-rich, Polyphonic Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
December 02, 2021, 12:47:10 AM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
December 01, 2021, 10:30:50 PM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
December 01, 2021, 09:10:11 PM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
December 01, 2021, 06:36:14 AM
post Re: DRSSTC build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
November 30, 2021, 08:10:17 PM
post DRSSTC build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
balazs
November 30, 2021, 06:55:58 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 30, 2021, 06:23:03 AM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
davekni
November 30, 2021, 05:58:42 AM
post Re: gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 30, 2021, 05:35:58 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 30, 2021, 01:50:18 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
futurist
November 30, 2021, 01:19:18 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 30, 2021, 12:07:59 AM
post gate drive transformer method
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
November 29, 2021, 11:45:44 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 29, 2021, 10:52:43 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Intra
November 29, 2021, 03:15:23 PM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
TiagoBS
November 29, 2021, 03:08:58 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Netzpfuscher
November 29, 2021, 12:15:12 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 29, 2021, 12:26:28 AM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
davekni
November 29, 2021, 12:07:30 AM
post Re: SG3525 push pull snubber calculation
[Transformer (Ferrite Core)]
davekni
November 28, 2021, 11:58:24 PM
post GDT (Gate Drive Transformer) tutorial
[Beginners]
davekni
November 28, 2021, 11:40:56 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
MRMILSTAR
November 28, 2021, 10:21:11 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
johnnyzoo
November 28, 2021, 10:05:40 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
November 28, 2021, 08:13:08 PM
post Re: Infrastructure and Architecture
[General Chat]
futurist
November 28, 2021, 06:12:44 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
MRMILSTAR
November 28, 2021, 04:48:04 PM
post Re: SG3525 push pull snubber calculation
[Transformer (Ferrite Core)]
PowerTech
November 28, 2021, 03:16:11 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 28, 2021, 09:36:10 AM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
plasma
November 28, 2021, 05:32:16 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 28, 2021, 04:28:33 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 28, 2021, 02:19:00 AM
post Re: Where to buy DIY or home made capacitor book(s)?
[Capacitor Banks]
huntergroundmind
November 28, 2021, 01:58:12 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 28, 2021, 12:53:27 AM
post Re: Driverless SSTC
[Solid State Tesla Coils (SSTC)]
davekni
November 28, 2021, 12:32:09 AM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
davekni
November 28, 2021, 12:16:04 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 27, 2021, 11:42:08 PM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
304er
November 27, 2021, 11:32:12 PM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
jpvvv123
November 27, 2021, 11:09:43 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
paulj
November 27, 2021, 10:06:41 PM
post Re: SG3525 push pull snubber calculation
[Transformer (Ferrite Core)]
PowerTech
November 27, 2021, 09:40:34 PM
post Re: SG3525 push pull snubber calculation
[Transformer (Ferrite Core)]
davekni
November 27, 2021, 08:51:05 PM
post Re: Infrastructure and Architecture
[General Chat]
Da_Stier
November 27, 2021, 08:09:50 PM
post Re: SG3525 push pull snubber calculation
[Transformer (Ferrite Core)]
PowerTech
November 27, 2021, 06:00:42 PM
post Re: Someone built Big TC
[Spark Gap Tesla Coils (SGTC)]
MRMILSTAR
November 27, 2021, 05:04:46 PM
post Re: Someone built Big TC
[Spark Gap Tesla Coils (SGTC)]
304er
November 27, 2021, 04:45:14 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Mads Barnkob
November 27, 2021, 07:59:37 AM
post Re: Contest of motor slowness, or lowness of voltage?
[Science, Research and News In Other Fields Than Electronics]
Mads Barnkob
November 27, 2021, 07:52:59 AM
post Re: FPS1000HD unboxing and first impression
[High Speed Filming]
Mads Barnkob
November 27, 2021, 07:51:01 AM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
Mads Barnkob
November 27, 2021, 07:47:23 AM
post Re: Infrastructure and Architecture
[General Chat]
Mads Barnkob
November 27, 2021, 07:37:57 AM
post Re: Someone built Big TC
[Spark Gap Tesla Coils (SGTC)]
Mads Barnkob
November 27, 2021, 07:21:43 AM
post Re: BrOdin coil - High power Big sparks!
[Dual Resonant Solid State Tesla coils (DRSSTC)]
patracy
November 27, 2021, 06:06:59 AM
post Re: Someone built Big TC
[Spark Gap Tesla Coils (SGTC)]
304er
November 27, 2021, 05:27:27 AM
post Re: Kind of old single piece of glass plate capacitor
[Spark Gap Tesla Coils (SGTC)]
304er
November 27, 2021, 03:19:55 AM
post Re: Kind of old single piece of glass plate capacitor
[Spark Gap Tesla Coils (SGTC)]
304er
November 27, 2021, 02:31:46 AM
post Re: Kind of old single piece of glass plate capacitor
[Spark Gap Tesla Coils (SGTC)]
304er
November 27, 2021, 02:22:20 AM
post Driverless SSTC
[Solid State Tesla Coils (SSTC)]
bismallah
November 26, 2021, 11:59:27 PM
post Infrastructure and Architecture
[General Chat]
Da_Stier
November 26, 2021, 11:27:47 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
klugesmith
November 26, 2021, 11:17:55 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
MRMILSTAR
November 26, 2021, 08:24:39 PM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 26, 2021, 07:48:07 PM
post Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
TiagoBS
November 26, 2021, 07:44:25 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
davekni
November 26, 2021, 06:58:16 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
plasma
November 26, 2021, 05:40:37 PM
post Re: "Exploding" water
[Capacitor Banks]
MRMILSTAR
November 26, 2021, 04:39:07 PM
post Re: Kind of old single piece of glass plate capacitor
[Spark Gap Tesla Coils (SGTC)]
MRMILSTAR
November 26, 2021, 04:31:20 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Intra
November 26, 2021, 03:52:08 PM
post Re: "Exploding" water
[Capacitor Banks]
johnf
November 26, 2021, 09:17:07 AM
post Re: Kind of old single piece of glass plate capacitor
[Spark Gap Tesla Coils (SGTC)]
paulj
November 26, 2021, 08:45:34 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 26, 2021, 06:31:56 AM
post Kind of old single piece of glass plate capacitor
[Spark Gap Tesla Coils (SGTC)]
304er
November 26, 2021, 05:59:58 AM
post Re: FPS1000HD unboxing and first impression
[High Speed Filming]
Kamui
November 26, 2021, 05:12:14 AM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
304er
November 26, 2021, 05:07:10 AM
post Please Help Me Find Datasheed Of IGBT
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ItsChloeUwU
November 26, 2021, 04:08:22 AM
post Re: Contest of motor slowness, or lowness of voltage?
[Science, Research and News In Other Fields Than Electronics]
davekni
November 25, 2021, 07:35:57 PM
post Re: 13.56MHz ISM frequency HFSSTC (or perhaps HFDRSSTC)
[Solid State Tesla Coils (SSTC)]
davekni
November 25, 2021, 07:28:52 PM
post Re: Practical limitations in size for Marx or CW
[Voltage Multipliers]
davekni
November 25, 2021, 07:22:32 PM
post Re: "Exploding" water
[Capacitor Banks]
304er
November 25, 2021, 07:01:03 PM
post Practical limitations in size for Marx or CW
[Voltage Multipliers]
abstruse1
November 25, 2021, 05:58:34 PM
post Gas Discharge Tubes for Marx Generator?
[Voltage Multipliers]
abstruse1
November 25, 2021, 05:55:53 PM
post Contest of motor slowness, or lowness of voltage?
[Science, Research and News In Other Fields Than Electronics]
klugesmith
November 25, 2021, 05:50:35 PM
post "Exploding" water
[Capacitor Banks]
MRMILSTAR
November 25, 2021, 04:48:10 PM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
paulj
November 25, 2021, 10:52:44 AM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Netzpfuscher
November 25, 2021, 07:09:29 AM
post Re: 13.56MHz ISM frequency HFSSTC (or perhaps HFDRSSTC)
[Solid State Tesla Coils (SSTC)]
Steve Ward
November 25, 2021, 06:58:56 AM
post Re: My completed 14-stage Cockroft-Walton voltage multiplier
[Voltage Multipliers]
davekni
November 25, 2021, 05:51:03 AM
post Re: Some Starting Questions About My New DRSSTC ???
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
November 25, 2021, 05:13:17 AM
post Re: My completed 14-stage Cockroft-Walton voltage multiplier
[Voltage Multipliers]
MRMILSTAR
November 25, 2021, 04:50:11 AM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
davekni
November 25, 2021, 02:25:10 AM
post Re: My completed 14-stage Cockroft-Walton voltage multiplier
[Voltage Multipliers]
304er
November 25, 2021, 12:42:59 AM
post Re: 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
klugesmith
November 24, 2021, 11:03:52 PM
post Re: My completed 14-stage Cockroft-Walton voltage multiplier
[Voltage Multipliers]
MRMILSTAR
November 24, 2021, 10:00:47 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Intra
November 24, 2021, 02:32:28 PM
post 60hz synchronous motor on 50hz?
[Spark Gap Tesla Coils (SGTC)]
paulj
November 24, 2021, 08:28:50 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