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Problems Driving HGTGs30N60A4D

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Gabriel35

Tue Mar 10 2015, 08:14PM

Registered Member #2310 Joined: Wed Aug 19 2009, 08:04PM
Location: Santa Catarina - Brazil
Posts: 169

Hello!

I'm playing with some circuits here, and I got something strange happening.

I'm building an "Kim Ladha" variant of Induction heater using the same IR2184 Mosfet driver , but using 30N60s instead of 20N60s

It simply don't work! I've checked all waveforms with oscilloscope and everything is ok.

If I Switch the h-bridge for one made with IRFPs260N the circuit works perfectly. And I Simply can't drive the HGTGs.

I've tried 2 different pairs of them and the same result...

Measured them with Multimeter and saturated it with a 15v supply and it Switches on/off normally.

Maybe the components are "false" or I'm getting insufficient gate drive? Somebody have a clue?

Thank you!

mister_rf

Tue Mar 10 2015, 09:15PM

Registered Member #4465 Joined: Wed Apr 18 2012, 08:37AM
Location: Bucharest, Romania
Posts: 145

If thatâ€™s not so difficult to you, can you post the schematics?

Gabriel35

Tue Mar 10 2015, 09:35PM

Registered Member #2310 Joined: Wed Aug 19 2009, 08:04PM
Location: Santa Catarina - Brazil
Posts: 169

There it go...
I'm using HGTG30N60A4D instead of HGTG20N60A4D

The rest of it is exactly the same... And work well with MOSFET bridges, (IRFP260, 460N for example)

1426023346 2310 FT169641 1202060083 1217 Ft36475 Inductionheaterschematic

Gabriel35

Thu Mar 12 2015, 03:09AM

Registered Member #2310 Joined: Wed Aug 19 2009, 08:04PM
Location: Santa Catarina - Brazil
Posts: 169

I've made a test:

A bridge of two IRFP460s work but the temperature of the mosfets go up within seconds, Its hard to touch them with about 20 seconds of operation on low voltage.

A bridge made of two IRFP260N works nice and smooth and all the waveforms are perfect...

I believe that something about RDS (On) or timing somewhere is doing this. I don't know exactly what... Any ideas?

Maybe insufficient gate driving, but i doubt it... This drive delivers 1,8A the only problem is that it's not isolated (HV section from low voltage control electronics), and if I'm right that's the reason for most people using UCCs ou TCs with GDTs.

Inducktion

Thu Mar 12 2015, 06:39AM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

So you checked the gate drive waveforms for /all/ of the different transistors you used?

It sounds quite a bit like something is having problems driving the gates of everything, but looking at the datasheets for the MOSFETS and IGBT's they appear to have very similar characteristics. It could potentially be RDSon that's causing the IRFP460's to heat up so much, since, comparatively, to the IRFP260's they have quite high resistance.

I'd make sure you have genuine components, firstly.

And as far as the actual gate drive goes; Personally, I've actually never had luck using those half bridge driver IC's. I don't know if it's because I'm unlucky or because they hate me, but they've literally never worked for me. A pair of UCC's, and a GDT however have NEVER failed me before, plus you'll get OODLES more driving current, significantly less heat in your switches, logic isolation, and just all around better performance compared to those half bridge IC's. Hell, depending on the phasing you might have nearly no heat in your switches at all; when I built a 1.8 kW induction heater using FDL100N50F's, even with their massive 12 nF's of gate capacitance, they basically never rose more than a couple degrees above ambient temperature.

Gabriel35

Thu Mar 12 2015, 02:45PM

Registered Member #2310 Joined: Wed Aug 19 2009, 08:04PM
Location: Santa Catarina - Brazil
Posts: 169

Thats nice to know...

So, i dont have the UCCs here... Do you think that's a good ideia using a h-bridge of smaller mosfets switching a GDT instead of the IR2184 directly?

going to be like this: IR2184 -> H-bridge of IRF540 -> GDT -> HV H-bridge.

About the GDT, how do I know if their waveforms are good or not?
I've tried sometimes a smaller h-bridge driving the GDT and the results were not good at all, the waveforms (with the gdt disconnected) were terribly strange...

Kolas

Wed Mar 18 2015, 08:42PM

Registered Member #102 Joined: Thu Feb 09 2006, 08:15PM
Location: Raleigh, NC
Posts: 169

The output of a GDT should in theory look exactly like the input. In this case, square. Once loaded down with the gates of the switches(with gate resistors in series.) The waveform will have some initial ringing, and look slightly curved at the switching transitions of the gate drive circuitry.

Gabriel35

Thu Mar 19 2015, 02:44AM

Registered Member #2310 Joined: Wed Aug 19 2009, 08:04PM
Location: Santa Catarina - Brazil
Posts: 169

Please take a look here:

And now, i've figured out that just one mosfet on the bridge heats up, the other don't... It's so difficult to understand...

With the bidge of IRFP260N everything is fine!

mister_rf

Sun Mar 22 2015, 09:40AM

Registered Member #4465 Joined: Wed Apr 18 2012, 08:37AM
Location: Bucharest, Romania
Posts: 145

By the way, in my opinion, the 47ohms, on the charge pump generate the high-side drive output power supply, is too much resistance, try to decrease it up to few ohms.

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