What about big GTO Thyristor ?

[manie]

Following from my Mosfet problem, I do not trust these little devices for real world HARD work anymore.

Question: Could I use a "Gate Turn Off" (GTO) Thyristor ?

It seems the power supply will be much more elaborate requiring a +V/0V/-V supply to turn the darn self-latching GTO off. Apparently they require -V at about 20% current of the load current to turn off. Like Jeremy Clarkson says "some say..." it has very fast switching (on/off) times. However, will the GTO respond to 4kHz PWM at various duties ?

Cat amongst the pigeons or latteral thinking ? Your thoughts highly sought after and appreciated.

Manie

 

[BeanieBots]

For "real world HARD work ", your best bet is to use MOSFETs.
Tried, tested, proven, used world wide and loads of support on how to drive them properly.
If want to use something obscure such as GTO thyristor, then you are on your own. Read the datasheet. Probably a lot harder to drive (properly) than a FET.

 

[Dippy]

Manie,

Like BB says, MOSFETs are a really good method.

Have you got a problem sourcing proper MOSFET drivers?
Driver Data Sheets even give clues on how to wire them up.

And who's to say you won't have even more problems with thyristors? (I suspect you will).
And who's to say your new Thyristor thread won't be 10x longer than your MOSFET one ?

I haven't got a clue how to drive GTO Thyristors.
Step 1 read Data Sheet. Step 2 read manufacturer's App Notes if possible. Step 3 pinch a schematic from the nerdynet. Step 4 try it. Step 5 go back to MOSFETs.

If you come round and replace my car headlamp bulb (properly) then I'll read the Data Sheet for you - can't say fairer than that.

If you get yourself a suitable driver, wire it in the suggested way, using suitable PCB techniques, with the recommended components you'll wonder what all the fuss was about.
Unless there is a problem with sourcing components (either stock or geography) I cannot understand why all this twiddling and heartache is worth £1.50 for a driver(??)

Yours sincerely,
George.

 

[Andrew Cowan]

Hove yout tried reducing the switching frequency of the PWM signal? That would massivly reduce heat. (It would require a lower clock speed, or poking a register. Do a search).

A

 

[manie]

Datasheet downloaded and read

I've done that guys, but thanks for the confirmation on what I thought after reading. GTO's just seem a LOT more robust ! Sourcing components is usually not the problem. The problem for a "serious" hobbyist is WHAT to get I have just acquired some IRFP 064N Mosfets. They are spec'd at 60V/70A and comes in a TO-247AC package. Somehow I think that might be better than TO-220 packs.

Oh yes ! Did you know that GTO's are succeptible to failure due to "COSMIC RAY PARTICLE STRIKES... " !!!!! Oh brother....

With that I think this thread has now died....? Back to Mosfets and this time AGAIN with IC drivers. Hope this time it works better..

Manie

 

[BeanieBots]

Every single semiconductor is succeptible to cosmic ray particle strikes.
Bigger current handling and higher voltage specs does not make anything less fragile.
Package type will not affect failure due to abuse.
Bigger is HARDER to drive and MORE likely to fail when driven incorrectly.

Please read all the data that was given & linked to. It explains how and why that is.

 

[kevrus]

Oh yes ! Did you know that GTO's are succeptible to failure due to "COSMIC RAY PARTICLE STRIKES... " !!!!! Oh brother....

Does that mean that my GTO thyristor triggered 'photon torpedoes' will not launch?

Seriously, with ref to your mosfet post, electric vehicle controllers use mosfets and switch several hundred amps at frequencies in excess of 15 KHz into highly inductive loads (motors) so they should be capable of doing what you want

 

[westaust55]

GTO Thyristors

Early Variable Speed (frequency) drives used thyristors and GTO thyristors.

To enable use of higher carrier (switching) frequencies, most VSD's have moved on the insulated gate bipolar transistor (IGBT) for frequencies from 4kHz to around 20kHz.

Thyristors are now mainly only used for cyclocoverters where the output frequency to the motor is of the order of 10 Hz and less.

GTO thyristors have long switch off times. First, the forward current falls, then there is a long time with a residual current flow until all remaining charge from the device is taken away. This restricts the maximum switching frequency to approx 1 kHz.

 

[premelec]

I've forgotten what your MOSFET failure mode was - you might like IGBTs - if you weren't blowing up the gates...