Author Topic: first test of driver UD 2.7C  (Read 1177 times)

Offline JCF

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first test of driver UD 2.7C
« on: May 04, 2021, 07:17:08 PM »
Hello all,
I had planned to replace a driver (chinese) which works correctly with a full bridge. for which I have already sent several posts in the forum
see https://highvoltageforum.net/index.php?topic=1386.0

the Chinese yumbao driver worked correctly with the full bridge (GDT, 2 IGBT; CM200- DU -12F)

I started testing the UD2.7 driver since 3 weeks, with resistors instead of the tesla coil everything is ok
to day I make connections to use the new ud2.7C big problem : the driver and the gdt (test winding) does not give very satisfactory signals without HT



after I put into service a HT about 80V the current of the 24V power supply UD2.7C was high (2.9A???) and the protections: diodes on resistance and protection diode 1N5819  and J18Ca were very hot (smell burn)

On the diagram there are 4 diodes on the gate resistance

I didn't understand anything, tomorrow I'm welding new components

« Last Edit: May 08, 2021, 05:58:48 PM by JCF »

Offline davekni

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Re: first test of driver UD 2.7C
« Reply #1 on: May 04, 2021, 09:02:34 PM »
I'm not sure what "HT" refers to, nor exactly what signals you are probing.

Likely issue is that UD2.7 with 24V supply is driving +-24V signals to gates.  You are using 18V TVS diodes for gate clamps.  Either the UD2.7 supply needs to be reduced to 18V, or the TVS diodes need to be increased to 24V or 27V.
David Knierim

Offline JCF

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Re: first test of driver UD 2.7C
« Reply #2 on: May 05, 2021, 09:40:40 AM »
Hi,
What say about the maximum gate voltage of 20V of IGBT with 24 or 28V TVS diodes.
Sorry for the absence of comment concerning the oscillo traces : it is an additional winding on the GDT for the measurements, I find that the shape of the signal is not good. Other thing when I increase the frequency of GDT signal? I heard a noise coming from the UD2.7C driver, is that normal?
« Last Edit: May 05, 2021, 10:40:13 AM by JCF »

Offline GrantV

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Re: first test of driver UD 2.7C
« Reply #3 on: May 05, 2021, 11:04:35 AM »
Hi JCF,

David is definitely the best person to ask but I'll give you my input here as well :-)

What say about the maximum gate voltage of 20V of IGBT with 24 or 28  TVS diodes.
The IGBT gates can definitely be driven harder than the specified 20V. I am also driving mine from 24V supply from the driver and am using 26V TVS diodes.

Sorry for the absence of comment concerning the oscillo traces : it is an additional winding on the GDT for the measurements, I find that the shape of the signal is not good.
If this is your gate drive scope signal then I would be interested to see:
1. What your test circuit looks like?
2. What your GDT looks like? What core? How many turns? What wire have you used? etc.

You say that your current is very high and that your components are getting very hot. This makes me think that you do not have enough turns on your GDT and/or have too low resistance on your gate drive?

Other thing when I increase the frequency of GDT signal? I heard a noise coming from the UD2.7C driver, is that normal?
If you are hearing 'ringing' or a high pitch 'whine' then that would be your GDT and is probably normal.

BUT if it is a loud 'buzzing' then I think you may be over saturating your GDT as in loneocean's notes:


On the diagram there are 4 diodes on the gate resistance

I didn't understand anything, tomorrow I'm welding new components
The gate drive resistor helps to slow down the turn-on of the IGBT and the reversed diode across the gate drive resistor helps to make the turn-off of the IGBT fast. This helps to ensure that your bridge does not go into a shoot through condition.


Just a personal note here, and I am hoping that David could help or shed some light? I think that the diodes across the gate resistors should be substantial schottky diodes and not normal small signal diodes. I would not expect the 1N4148's to handle the ultra fast switching speed or the temperature rise very well over time?
« Last Edit: May 05, 2021, 11:06:35 AM by GrantV »

Offline JCF

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Re: first test of driver UD 2.7C
« Reply #4 on: May 05, 2021, 06:02:21 PM »
Hi,
Thank you GrantV for post.

First here is an last update of the full power bridge diagram. Today I placed an order for TVS 26V.
the diodes in parallel with the gate resistance are Schottky 1N5819.
The operation of the driver is improved with a better current sensor on the primary and correct signal interruptor.
To morow I make a post with measurement of output bridge signal and current in the primary coil.
The GDT is made with EPCOS, Toric core material N30 5750nH dimensions 37.5 (Dia.) x 16.2mm. the windings is RJ45 torsaded wires, 12  tours.




« Last Edit: May 05, 2021, 06:48:14 PM by JCF »

Offline davekni

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Re: first test of driver UD 2.7C
« Reply #5 on: May 05, 2021, 06:38:06 PM »
Quote
David is definitely the best person to ask but I'll give you my input here as well :-)
Grant:  Actually you and others here on this forum have more experience with IGBT gates surviving fine at 24V.  I built my DRSSTC just before finding this forum, so used 18V for gate drive to stay under the 20V spec. limit.
David Knierim

Offline GrantV

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Re: first test of driver UD 2.7C
« Reply #6 on: May 05, 2021, 06:57:17 PM »
Quote
David is definitely the best person to ask but I'll give you my input here as well :-)
Grant:  Actually you and others here on this forum have more experience with IGBT gates surviving fine at 24V.  I built my DRSSTC just before finding this forum, so used 18V for gate drive to stay under the 20V spec. limit.

LOL well then best not to take my word for it because I only overdrive my gates because Gao intimated that it was a good idea in his description of the UD2.7C driver and I think he took it from Steve Ward's original design ;-)

Offline davekni

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Re: first test of driver UD 2.7C
« Reply #7 on: May 05, 2021, 07:03:25 PM »
That is why I included "others" here too.  Mads is the expert.  Most UD2.7 designs run at 24V, so gates at +-24V.  That obviously works fine for many people.  I've seen scope plots with gate peaks to 35V and no resulting gate breakdown.
David Knierim

Offline Mads Barnkob

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Re: first test of driver UD 2.7C
« Reply #8 on: May 05, 2021, 10:13:16 PM »
The idea of overdriving the gate is to help the IGBT lessen the losses from the higher switching currents. Even with softswitching we have some hardswitching due to phase shifting.

The gate oxide layer should not break down until 80VDC, the reason for 20VGE limits in datasheets are for reliability and current limiting. The higher the gate voltage, the higher the current through the C-E junction can get. This usually turns out fatal during a motor fault in a regular inverter they were designed for. So a lot of the specifications are in place to uphold the 1ms short circuit rating of a brick, which I think corresponds to some fuse times.

I am not sure about expert, but passionate for knowledge in the field of Tesla coils works too ;)
https://kaizerpowerelectronics.dk - Tesla coils, high voltage, pulse power, audio and general electronics
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Offline JCF

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Re: first test of driver UD 2.7C
« Reply #9 on: May 06, 2021, 04:04:09 PM »
Hi,
here are the measurements made this morning. power supply conditions UD2.7 24V, frequency about 300khz (generator to feedback input) high voltage bridge power supply: 50V. Mesure bridge outpout with differential probe (x50).

for the phase setting I do not see any effect (frequency?) with the jumper up or down?

there is a lot of oscillation on the brige output after the start of the rising edge?

at 150Vdc High Voltage I hear the noise caused by square signals and very fine sparks (too much daylight to see what is happening)

With my Chinese driver and a low switch frequency at 10Hz (on OPF2412)  there were multiples sparks (from 8 to 15CM) with big sound

Why ? ? ?

the duration of the pulses and the frequency sent to the HFBR 2412 may be too short (interrupter: duty 3.6µs - 26 µs, frequency 126 - 980Hz) ?

further in the cycle, the oscillations are almost gone last photos



« Last Edit: May 06, 2021, 04:34:07 PM by JCF »

Offline davekni

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Re: first test of driver UD 2.7C
« Reply #10 on: May 06, 2021, 07:03:25 PM »
Phase lead adjustment will have no effect when running open-loop.  Open-loop phase is determined by slight differences between resonant frequency and signal generator frequency.  Open-loop, phase also changes some across the burst and energy transfers from primary to secondary and back.

The H-Bridge output "spikes" you see are normal when phase-lead is almost enough.  One set of IGBTs turns off, remaining primary current causes H-Bridge voltage to transition.  Then primary current reverses, causing another transition.  Then the opposite IGBTs turn on, causing a third transition.  Since phase lead is changing across the burst (due to open-loop operation), the "spikes" show up in only the one place.

Open-loop, sparks depend on exact frequency matching.  Tiny changes in coil or generator frequency will prevent sparks.

These CM200 bricks appear to be workable at 300kHz, although I haven't heard of anyone else running bricks at such high frequency.
David Knierim

Offline JCF

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Re: first test of driver UD 2.7C
« Reply #11 on: May 08, 2021, 05:14:46 PM »
Today, I post tesla coil measures with real feedback sense from TRIAD CTS 206-3A . Measure current is from one other CTS 206-3A with a charge of 100 Ohms (1:300) (
the value of the self is too high, I cannot do a better phase adjustment (the core is up) it's a 7M3-393 Coilcraft.

the Chinese yumbao driver worked correctly with the full bridge (GDT, 2 IGBT; CM200- DU -12F) and at 200v et low frequency interrupter (10Hz) there are sparks 10-15cm with loud noise, no musical sound

With UD2.7C at 24DC power supply, 200V on the bridge (no MMC), frequency interrupter 100Hz and pulse 60µS no visible sparks just good noise and plasma ?

I don't understand why this difference with the same full bridge and coil ? Can someone help me ?

primary and secondary resonance frequency are about 300khz.

TC0 DRIVER CHINESE / TC1 driver UD 2.7C






« Last Edit: May 10, 2021, 06:11:13 PM by JCF »

Offline davekni

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Re: first test of driver UD 2.7C
« Reply #12 on: May 08, 2021, 10:31:25 PM »
Looks like about 500ns of phase-lag shown.  The UD2.7 driver will need to add 500ns of lead to compensate, 30-40uH for L1.
David Knierim

Offline JCF

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Re: first test of driver UD 2.7C
« Reply #13 on: May 10, 2021, 04:37:53 PM »
Hi,
following the deficit of sparks produced, I decided to put two Chinese drivers back into service....
as with UD2.7C I have no more spark .....
I see a normal signal at the output of the bridge, the gate signals are correct on the IGBTs.
the high voltage power supply is 50- 230V DC (current ? I don't know how to measure ?)
I checked the wiring of the primary and secondary is ok and repeat a measurement of the resonance frequency of the secondary 300khz and 160 ohms (wire dia 0.15mm 900tr) the coil resistance unchanged.
the secondary is well connected to earth.

so there, a great mystery

« Last Edit: May 10, 2021, 06:08:03 PM by JCF »

Offline JCF

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Re: first test of driver UD 2.7C
« Reply #14 on: May 24, 2021, 06:06:39 PM »
It was one wire of the first GDT : intermittent contact.

I always have problem with UD2.7C I don't have the good interrupteur.

Is it possible to connect with wire a pulse generator at the place of IFD95 ?

I have trouble to make a generator with emitter HFBR1412 (control circuit)
« Last Edit: May 24, 2021, 06:09:00 PM by JCF »

Offline davekni

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Re: first test of driver UD 2.7C
« Reply #15 on: May 25, 2021, 04:20:39 AM »
It would be possible to feed in a signal generator if you circuit is well shielded, the generator is fed with coax cable, and the cable has ferrite beads around it (or even better a few turns around a large ferrite E-core), and the coax shield is well connected to your local driver Faraday cage (shielding).

Another option I'd suggest instead:  Drill a hole in the end of a 660nm red LED and glue the fiber end into the hole.  I show a close-up image of that in this thread:
https://highvoltageforum.net/index.php?topic=1263.msg9353#msg9353
David Knierim

Offline JCF

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Re: first test of driver UD 2.7C
« Reply #16 on: May 30, 2021, 04:03:54 PM »
Thank you

I manage to have sparks in opencircuit with generator (310KHz)...

with one of the current sense (1: 300), I get square sigals at the bridge output but no sparks

what is the operating mode to adjust the frequency

on a full bridge made with IRFP460 I have better and more longer sparks than with CM200DU-12F (frequency is too high ?)

could a big cable of 1m50, between bridge output and primary or 1 meter cable between output bank (1200µF) and bridge input , be at the origin of the malfunction?
« Last Edit: May 30, 2021, 04:26:36 PM by JCF »

Offline JCF

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Re: first test of driver UD 2.7C
« Reply #17 on: May 31, 2021, 06:01:17 PM »
Hi,
I remade 2 other GDT, the first were made with 3 wires coming from a multibruns ethernet cable.
they use the same N30 ferrite ferrites with 3 sheathed wires but in 0.6mm diameter single-strand copper.
I find that the signal is cleaner especially at the passage through 0 where the vertical are more important (signal of IGBT gate)
What do you think about ?
pict 1 : multibrun and with the signal of bridge output
pict 2 : monobrun


« Last Edit: May 31, 2021, 06:15:33 PM by JCF »

Offline davekni

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Re: first test of driver UD 2.7C
« Reply #18 on: May 31, 2021, 10:34:42 PM »
Quote
on a full bridge made with IRFP460 I have better and more longer sparks than with CM200DU-12F (frequency is too high ?)
CM200DU-12F may require more phase-lead in the driver to compensate for slower switching.  If the driver is not adding phase lead, then the CM200DU-12F delay may be enough to limit performance at 300kHz.

Quote
could a big cable of 1m50, between bridge output and primary or 1 meter cable between output bank (1200µF) and bridge input , be at the origin of the malfunction?
1.5m from bridge output to primary will add inductance, lowering effective coupling factor and lowering primary frequency.  If primary frequency is tuned to match (slightly below) secondary frequency with the cabling included, then the effect will not be too severe.  1m to output bank will likely cause H-Bridge voltage spikes at switching points, depending on how large local snubber capacitors you have at the H-Bridge.  Spikes are more of an issue with frying IGBTs than with performance.

Stranded vs. solid wire doesn't make any significant difference for GDT construction.  The differences must be due to how lead wires were twisted after winding, or length of lead wires, or some other factor.

The gate waveforms show roughly-identical rise and fall times.  Do you have diodes across gate series resistors to speed up turn-off?  Diodes are generally necessary to get sufficient dead-time (turn-off before turn-on of opposite IGBTs).
David Knierim

Offline JCF

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Re: first test of driver UD 2.7C
« Reply #19 on: June 01, 2021, 04:07:13 PM »
Thank you Dave.
here are the measurements made on the full bridge output signal with IRFP 460. It is less disturbed than with the IGBT. the cables are shorter, especially in full bridge output to primary coil.
There is a phase shift, but I don't have a choke to compensate

I will remake a coil with 1400 or 1600 turns on a PVC diameter of 80mm. This will lower the resonance frequency below 200KHZ. What about primary 90° 0° ?

Next steep wiring a new coil

« Last Edit: June 01, 2021, 06:48:09 PM by JCF »

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Re: first test of driver UD 2.7C
« Reply #19 on: June 01, 2021, 04:07:13 PM »

 


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