Author Topic: Half bridge strange behavior  (Read 177 times)

Offline AstRii

  • High Voltage Technician
  • ***
  • Posts: 123
  • Karma: +3/-0
  • Czech Technical University in Prague
    • View Profile
Half bridge strange behavior
« on: May 24, 2021, 06:17:08 PM »
Hello,
Recently I ordered some nice russian doorknob capacitors to make a 14 stage voltage multiplier.
I have tried to use ZVS driver to run it, but that setup could not provide much more than 500W. I've decided to create a half-bridge driver to supply a few kilowatts of power.

I had one old IGBT brick laying around which I used: MG150Q2YS40 (datasheet attached).
I realize that this IGBT is quite old and slow, so I keep the driving frequency low (20kHz).

I noticed that when I power the circuit from ~60VAC, it draws almost 2A at no load, which is quite terrible. The IGBT and the heatsink reach like 50C after a few minutes of runtime *with no load*.
First I thought it could be a cross-conduction issue, even with quite a lot of deadtime, as these IGBTs are so slow, there might be some cross-conduction anyway. So I have increased the gate resistance from 5.6Ohms to 15Ohms, which reduced the current consumption by ~200mA. So it seems to help, so afterwards I put 22ohms resistors instead. This time the current decreased by only ~20mA. But the setup is still drawing 1.78A at 60VAC, still a terrible power loss.

I don't know how much I can trust my clamp meter, but 60V*2A power loss would agree with the temperature rise of the heatsink. Most of this power is definitely lost there.

The setup is quite straightforward:
Drive signal is generated with a simple Arduino, it's a 5V square wave with 50% duty cycle. This square wave is then fed into ucc37321/2 pair of inverting and noninverting FET drivers which drive a GDT with a 1uF capacitor in series with primary.
GDT is wound on a rather big ferrite core and uses 6 primary turns, and 2 secondaries with 10turns each. The primary is driven at 12V which should give me ~20V on the secondaries.
Gates of the IGBTs are connected with 1R resistor + diode combo for discharge and 22R resistor for charge.

The power is supplied with 5kVA variac through a 2kVA insulating transformer and then straight into a full bridge rectifier with 5000uF of bus capacitance.
I'm using 2 parallel 1200V 330nF WIMA capacitors on the bus as snubber caps.

Voltage divider capacitors are quite heavy duty 1200V 2.2uF snubber capacitors.

Here is a photo of the setup:


Gate drive waveforms 5V/div 10us/div:


Gate drive waveforms 5V/div 2us/div:


Output voltage of the inverter 10V/div 10us/div:

Output voltage with no load is very weird! When powered with 60VAC -> (84VDC) after rectification. Shouldn't the output waveform be a beautiful looking 84Vpk-pk square-wave?
The output voltage is not even 40Vpk-pk! Which means I'm losing 44V somewhere.
I also very much dislike the overshoot and the ringing, I have put an RC snubber on both IGBTs (22nF + 15R combination). It didn't help at all.

Just to be sure I've also measured the output voltage of the insulation transformer (It outputs 54VAC when supplied 60VAC from variac, I think that's okay, maybe the winding ratio is not perfectly 1:1?):


Anyway I also measured the DC voltage on the bus capacitance, and it only reads 66V! 54VAC rectified should make for roughly 73V after the full bridge rectifier! That's also quite weird.


Anyone has any suggestions as why is the output voltage so strange and where is the power getting lost?
I'm not ready to believe that so much power is lost just as switching losses. Especially considering these transistors are made for 150A of continuous current!
I'll appreciate any advice! Thank you.















Offline AstRii

  • High Voltage Technician
  • ***
  • Posts: 123
  • Karma: +3/-0
  • Czech Technical University in Prague
    • View Profile
Re: Half bridge strange behavior
« Reply #1 on: May 24, 2021, 07:28:07 PM »
*FOUND THE PROBLEM*

Oh my gosh how could I be so blind. I was just a very bad connection! Sorry for anybody who lost time reading through all of this.

Look what I've made:


I've connected the negative rail of the capacitor divider to the E1/C2 output of the IGBT brick instead of ground.
No wonder it didn't work.
I've been looking at it for 3 days and just as I wrote this post I realized the mistake :D

The output is now very clean 80Vpk-pk square-wave when powered from 60VAC and the no-load input current is 70mA. Everything working great!


Offline MRMILSTAR

  • High Voltage Engineer
  • ****
  • Posts: 281
  • Karma: +8/-0
  • Cedar Rapids, Iowa
    • View Profile
Re: Half bridge strange behavior
« Reply #2 on: May 24, 2021, 10:33:53 PM »
You should have been able to get a very respectable output of your multiplier with 500 watts. I recently completed a 14-stage CW multiplier driven by 2 flybacks in parallel powered by a COTS ZVS driver. The input to my multiplier is about 300 watts and I easily get 32 cm discharges. You can see details of mine in the "Voltage Multiplier" section.
Steve White
Cedar Rapids, Iowa
Retired electrical engineer

Offline AstRii

  • High Voltage Technician
  • ***
  • Posts: 123
  • Karma: +3/-0
  • Czech Technical University in Prague
    • View Profile
Re: Half bridge strange behavior
« Reply #3 on: May 25, 2021, 12:07:58 AM »
Well back then I only connected 4 stages, and the arcs were already quite "weak". I'm aiming for hot discharges.
But it's nice to see your multiplier working so well with only a ZVS driver powering it, that's cool!

High Voltage Forum

Re: Half bridge strange behavior
« Reply #3 on: May 25, 2021, 12:07:58 AM »

 


* Recent Topics and Posts

post Exploding phones and electronics, a mini-series of 50kA discharges!
[Capacitor Banks]
Mads Barnkob
Today at 08:27:10 PM
post Re: LCR meter recommendation
[Sell / Buy / Trade]
Mads Barnkob
Today at 08:23:57 PM
post Re: LCR meter recommendation
[Sell / Buy / Trade]
Max
Today at 02:51:45 PM
post Re: LCR meter recommendation
[Sell / Buy / Trade]
Da_Stier
Today at 02:01:23 PM
post LCR meter recommendation
[Sell / Buy / Trade]
the_anomaly
Today at 01:58:48 PM
post Re: The dramatic difference between wet and dry sphere splashes
[Science, Research and News In Other Fields Than Electronics]
Mads Barnkob
Today at 12:42:03 PM
post Re: The dramatic difference between wet and dry sphere splashes
[Science, Research and News In Other Fields Than Electronics]
haversin
Today at 02:49:00 AM
post Re: The dramatic difference between wet and dry sphere splashes
[Science, Research and News In Other Fields Than Electronics]
Mads Barnkob
June 16, 2021, 08:54:32 PM
post Re: The dramatic difference between wet and dry sphere splashes
[Science, Research and News In Other Fields Than Electronics]
davekni
June 16, 2021, 08:00:50 PM
post Re: The dramatic difference between wet and dry sphere splashes
[Science, Research and News In Other Fields Than Electronics]
haversin
June 16, 2021, 05:40:40 PM
post Demo Coil Protection
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
June 16, 2021, 05:39:14 PM
post Re: What is the guidence on SpaceX rockets based on ? PID's?
[General Chat]
Twospoons
June 16, 2021, 10:20:30 AM
post Re: What is the guidence on SpaceX rockets based on ? PID's?
[General Chat]
Patrick
June 16, 2021, 07:33:15 AM
post Re: Through-hole layout of UD2.7C universal driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
dbach
June 15, 2021, 01:21:38 PM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rapy2
June 15, 2021, 12:02:58 PM
post Re: Through-hole layout of UD2.7C universal driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
June 15, 2021, 06:52:56 AM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
June 15, 2021, 05:43:07 AM
post Re: Through-hole layout of UD2.7C universal driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
dbach
June 15, 2021, 05:26:34 AM
post The dramatic difference between wet and dry sphere splashes
[Science, Research and News In Other Fields Than Electronics]
haversin
June 15, 2021, 02:27:03 AM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rapy2
June 14, 2021, 01:06:02 AM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
June 14, 2021, 12:44:31 AM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rapy2
June 14, 2021, 12:41:33 AM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rapy2
June 14, 2021, 12:11:13 AM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
June 13, 2021, 11:52:11 PM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rapy2
June 13, 2021, 11:38:44 PM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rapy2
June 13, 2021, 10:26:51 PM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
June 13, 2021, 09:57:56 PM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rapy2
June 13, 2021, 09:29:08 PM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
June 13, 2021, 08:53:25 PM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rapy2
June 13, 2021, 07:22:05 PM
post Re: First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
June 13, 2021, 07:02:28 PM
post Re: HFSSTC with fixed crystal-controlled frequency
[Solid State Tesla Coils (SSTC)]
Steve Ward
June 13, 2021, 06:25:20 PM
post First middle sized DRSSTC - Phase lead tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rapy2
June 13, 2021, 02:48:59 PM
post OpenTheremin v3 loosing calibration after minutes
[Electronic Circuits]
gianpaolo
June 13, 2021, 12:00:09 PM
post Re: What is the guidence on SpaceX rockets based on ? PID's?
[General Chat]
Mads Barnkob
June 12, 2021, 07:28:03 PM
post Re: Rocket engine questions
[General Chat]
klugesmith
June 12, 2021, 07:23:12 PM
post Re: Rocket engine questions
[General Chat]
rikkitikkitavi
June 12, 2021, 12:24:06 PM
post Re: Nice PC Board Tesla
[Solid State Tesla Coils (SSTC)]
Da_Stier
June 12, 2021, 10:06:18 AM
post Re: Rocket engine questions
[General Chat]
plasma
June 12, 2021, 10:01:29 AM
post Re: Nice PC Board Tesla
[Solid State Tesla Coils (SSTC)]
Twospoons
June 12, 2021, 08:47:08 AM
post Re: What is the guidence on SpaceX rockets based on ? PID's?
[General Chat]
Patrick
June 12, 2021, 07:03:10 AM
post Re: Complications in the design of the first DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
PEDRO HENRIQUE
June 12, 2021, 06:42:56 AM
post Re: Nice PC Board Tesla
[Solid State Tesla Coils (SSTC)]
davekni
June 12, 2021, 04:20:53 AM
post Re: SKM100 Mini DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Willsmith001
June 11, 2021, 11:08:24 PM
post Re: How much propagation delay is too much propagation delay
[General Chat]
Willsmith001
June 11, 2021, 11:07:00 PM
post Re: Nice PC Board Tesla
[Solid State Tesla Coils (SSTC)]
Da_Stier
June 11, 2021, 12:33:55 PM
post Re: Nice PC Board Tesla
[Solid State Tesla Coils (SSTC)]
futurist
June 11, 2021, 12:03:24 PM
post Re: How much propagation delay is too much propagation delay
[General Chat]
davekni
June 11, 2021, 06:47:52 AM
post Re: How much propagation delay is too much propagation delay
[General Chat]
Power-Max
June 11, 2021, 06:32:02 AM
post Re: How much propagation delay is too much propagation delay
[General Chat]
davekni
June 11, 2021, 05:16:03 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