Author Topic: Calculating Hard-Switching losses  (Read 539 times)

Offline Phoenix

  • High Voltage Enthusiast
  • *
  • Posts: 42
  • Karma: +0/-0
    • View Profile
Calculating Hard-Switching losses
« on: July 31, 2018, 05:37:45 PM »
Hello  :)

I would like to calculate the maximum frequency i can drive an IGBT-Brick within its thermal limitation. I am using SKM200GB128D Bricks.

I am calculating the losses for 180A Hardswitching and a frequency of 20kHz. I need to find out the turn on/off energy first using the datasheet.


And here is my question: When reading the energy of the chart, do i need to use the 180A of current or the change of current (dI/dt)? The change of current would only be around 22.6A/µs high for 180A at 20kHz, which would result in much lower turn on/off energies.

Greetings,
Phoenix


Offline Mads Barnkob

  • Administrator
  • High Voltage Senior
  • *****
  • Posts: 851
  • Karma: +7/-0
  • Denmark
    • View Profile
    • Kaizer Power Electronics
Re: Calculating Hard-Switching losses
« Reply #1 on: July 31, 2018, 06:54:55 PM »
It is your peak current, that is how I calculated it for soft-switching here: http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/igbts/

I guess you can use my example all the way through, just ignore the reduction factors for resonant switching that I use :)
http://www.kaizerpowerelectronics.dk - Tesla coils, high voltage, pulse power, audio and general electronics

Offline Phoenix

  • High Voltage Enthusiast
  • *
  • Posts: 42
  • Karma: +0/-0
    • View Profile
Re: Calculating Hard-Switching losses
« Reply #2 on: July 31, 2018, 08:06:16 PM »
Thank you for your reply  :)

I have already followed your guide for the calculations but i am stuck at that point. In this application i am only switching  an inductive load, which results in a triangular waveform. The IGBT's always switch at the peaks of this waveform (180A). There is no resonance circuit, so the IGBT's always switch at full current. Because of that, i think i have to read the chart at 180A of current. But if i read the chart at the operating current, i can't keep up with the manufacturers claim of 220A at 20kHz with a junction temperature of 150°C and a case temperature of 80°C. Here are my calculations:


As you see i am only able to switch at a maximum frequency of 8.462kHz but according to the datasheet the bricks should be able to switch 20kHz at 220A.

Is there something wrong with my calculations?

Edit: I just tried something new and i think i have found the problem: A square wave has a RMS-Factor of 1, but a triangular wave only has a factor of 0,577. The maximum current rating in the datasheet is for DC, so there are no switching losses included. If i put in the numbers for 127A (220*0,577) into the equations, the result is 23,462 kHz and it should work for my inverter. Could this result be correct?

Greetings,
Phoenix
« Last Edit: July 31, 2018, 08:54:19 PM by Phoenix »

Offline Mads Barnkob

  • Administrator
  • High Voltage Senior
  • *****
  • Posts: 851
  • Karma: +7/-0
  • Denmark
    • View Profile
    • Kaizer Power Electronics
Re: Calculating Hard-Switching losses
« Reply #3 on: July 31, 2018, 09:24:55 PM »
I was just about to mention that, just like I had to reduce for soft-switching short pulses, as hard-switching is seen as a square wave, a triangle waveform would also have to use a reduction factor, but you already figured that out :)
http://www.kaizerpowerelectronics.dk - Tesla coils, high voltage, pulse power, audio and general electronics

Offline Phoenix

  • High Voltage Enthusiast
  • *
  • Posts: 42
  • Karma: +0/-0
    • View Profile
Re: Calculating Hard-Switching losses
« Reply #4 on: July 31, 2018, 10:27:35 PM »
I have now used the reduction factor for my 180A which gives me about 104A RMS. I used the RMS value for the CE Voltage and in the calculation for the conduction losses. But i have not used it for the turn on/off energy, because the IGBT still has to switch the 180A peak.

According to my calculations, if the junction has a temperature of 125°C and the Case has a temperature of 50°C, i can run my Inverter up to 20,6kHz. I also converted the equation to tell me the temperature difference between junction and case, at 20kHz the difference would be 73°C. I could now use a circuit which cuts of the supply voltage to the inverter using a relay, when the case temperature reachs 57°C, so the junction would never get hotter than 130°C  :D

Greetings,
Phoenix
« Last Edit: July 31, 2018, 11:57:15 PM by Phoenix »

Offline rikkitikkitavi

  • High Voltage Enthusiast
  • *
  • Posts: 14
  • Karma: +1/-0
    • View Profile
Re: Calculating Hard-Switching losses
« Reply #5 on: August 17, 2018, 03:44:38 PM »
Just a thought, wouldnt average value instead of RMS be more accurate?

The loss is the integral of the current*voltage across the switching device during the switching event.
A man can not have to many variacs

Offline Phoenix

  • High Voltage Enthusiast
  • *
  • Posts: 42
  • Karma: +0/-0
    • View Profile
Re: Calculating Hard-Switching losses
« Reply #6 on: August 17, 2018, 04:47:21 PM »
I only used the RMS Value for the calculation of the conduction losses during the ON-State.

For the losses during the switching event, i used the full 180A, because the IGBT's switch at the current maximum.

Offline Hydron

  • Administrator
  • High Voltage Technician
  • *****
  • Posts: 192
  • Karma: +4/-0
    • View Profile
Re: Calculating Hard-Switching losses
« Reply #7 on: August 18, 2018, 03:26:03 PM »
Conduction losses for an IGBT should probably be done with the average (mean) current rather than RMS - they behave more like a diode than a resistor in forward conduction. RMS is appropriate for MOSFETs though, and it probably won't make a lot of difference anyway.

High Voltage Forum

Re: Calculating Hard-Switching losses
« Reply #7 on: August 18, 2018, 03:26:03 PM »

 


* Recent Topics and Posts

post Re: My First DRSSTC
[Dual Resonant Solid State Tesla coils]
sjsimmo
Today at 08:08:58 AM
post Re: How to calculate VA rating and other things for Ferrite Core? (SMPS)
[Transformer (ferrite core)]
sjsimmo
Today at 01:24:15 AM
post How to calculate VA rating and other things for Ferrite Core? (SMPS)
[Transformer (ferrite core)]
FilipŠebík
January 18, 2019, 07:32:38 PM
post Re: How to design a 7.5kV AC source?
[Transformer (ferrite core)]
profdc9
January 18, 2019, 04:25:14 PM
post How to design a 7.5kV AC source?
[Transformer (ferrite core)]
CristianM
January 18, 2019, 03:48:06 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
the_anomaly
January 17, 2019, 02:01:36 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 16, 2019, 04:26:38 AM
post AC vs DC fuses, high current, explosive destructive testing and theory
[Capacitor banks]
Mads Barnkob
January 15, 2019, 09:48:48 PM
post Re: My X-Ray Machine
[X-ray]
neukyhm
January 15, 2019, 10:51:46 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 14, 2019, 05:08:38 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
the_anomaly
January 14, 2019, 01:15:53 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
Mads Barnkob
January 14, 2019, 12:22:07 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 11, 2019, 05:10:39 AM
post Re: My X-Ray Machine
[X-ray]
Max
January 10, 2019, 10:59:25 PM
post Re: 迎词、来
[General chatting]
profdc9
January 10, 2019, 06:56:59 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 10, 2019, 05:33:48 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General chatting]
black.yang
January 10, 2019, 02:11:58 AM
post Re: My X-Ray Machine
[X-ray]
Mads Barnkob
January 09, 2019, 09:14:59 PM
post Acoustic spectra of sung vowels by the FFT analyzer HP 3561A
[Electronic circuits]
Physikfan
January 08, 2019, 08:44:16 PM
post Re: IGBT failure in DRSSTC
[Dual Resonant Solid State Tesla coils]
Felix Bieri
January 08, 2019, 05:33:55 PM
post Re: Huawei RRU3928 1800MHz radio base station teardown (part 1 of 2)
[Radio frequency]
Mads Barnkob
January 08, 2019, 08:25:08 AM
post Re: SimpleDriver v2.3, my phase-shifting QCW DRSSTC controller
[Dual Resonant Solid State Tesla coils]
flyglas
January 08, 2019, 08:25:02 AM
post Re: SimpleDriver v2.3, my phase-shifting QCW DRSSTC controller
[Dual Resonant Solid State Tesla coils]
Hydron
January 08, 2019, 02:01:50 AM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Hydron
January 07, 2019, 10:23:38 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 07, 2019, 08:53:32 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 07, 2019, 08:17:44 PM
post Re: SimpleDriver v2.3, my phase-shifting QCW DRSSTC controller
[Dual Resonant Solid State Tesla coils]
Netzpfuscher
January 07, 2019, 07:37:53 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Uspring
January 07, 2019, 01:30:36 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 07, 2019, 12:43:26 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Hydron
January 07, 2019, 08:09:49 AM
post Re: SimpleDriver v2.3, my phase-shifting QCW DRSSTC controller
[Dual Resonant Solid State Tesla coils]
NEYi
January 07, 2019, 07:43:50 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General chatting]
Mads Barnkob
January 07, 2019, 06:48:06 AM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Mads Barnkob
January 07, 2019, 06:39:56 AM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 06, 2019, 09:23:19 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 06, 2019, 07:11:25 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Uspring
January 06, 2019, 07:02:14 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
flyglas
January 06, 2019, 12:43:46 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 06, 2019, 11:55:09 AM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
TDAF
January 06, 2019, 09:48:06 AM
post Re: First SSTC build, need help troubleshooting
[Solid state Tesla coils]
TDAF
January 06, 2019, 09:45:17 AM
post 关于: 这个便宜的 drsstc 驱动程序从 aliexpress 1.3 b 类型?
[Dual Resonant Solid State Tesla coils]
black.yang
January 06, 2019, 08:34:46 AM
post 迎词、来
[General chatting]
black.yang
January 06, 2019, 08:20:21 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
flyrod
January 06, 2019, 12:34:15 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 05, 2019, 05:27:23 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
flyrod
January 05, 2019, 03:46:29 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 05, 2019, 09:51:10 AM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Mads Barnkob
January 04, 2019, 11:02:25 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 03, 2019, 08:38:15 PM
post Re: SimpleDriver v2.3, my phase-shifting QCW DRSSTC controller
[Dual Resonant Solid State Tesla coils]
flyglas
January 03, 2019, 08:15:48 PM
post Re: Component questions
[Dual Resonant Solid State Tesla coils]
Mads Barnkob
January 03, 2019, 02:05:31 PM

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