Bidirectional IGBT AC switch?
Kolas, Fri Oct 21 2016, 05:18AMHey there guys. Here's a little idea I've been cooking up.
Two Series-Opposing IGBT's with parallel diodes. I've found some information regarding the use of this circuit for control of alternating current loads. But I am unsure. This circuit looks like it could be a drop in replacement for the use of triacs. Additionally, some other options appear to be available for output modulation. Switching would be done symmetrically on a half wave basis to avoid DC current within the transformer primary. Square wave signals will be supplied by a micro controller.
There are two options with this specific topology: connected emitters, and connected collectors.
My questions are as follows.
1. Will this circuit work to provide control of alternating current to a highly inductive load?
2. Is it more advisable to use connected emitters or connected collectors. If connected emitters can be used, should the gates be driven together or inversely?
3. Are snubber circuits necessary for proper operation?
Included is a quick drawing of what is implied. Sorry for it's crudeness.
I am considering this situation in order to avoid buying somewhat pricey triacs. The IGBT's referenced are ones already owned.
The goal is to provide a high degree of control (3-97%) over a fairly large welding transformer. (upcoming!) around 75A at 240v.
Thanks to everyone who took the time to read and possibly reply!
Kolas
Re: Bidirectional IGBT AC switch?
DerAlbi, Fri Oct 21 2016, 01:18PM
An inductive load tries to have a constant current, so the current keeps flowing even if the IGBTs are in the off-state. Thus inducing an overvoltage which will destroy the switches.
The way i see it you want to build a stepdown converter with fixed dutycycle so read about stepdown coverters and build it for one polarity, then think about how to incorporate the other halfwave. Just one step at a time after you actually understand what you are doing
DerAlbi, Fri Oct 21 2016, 01:18PM
1. Will this circuit work to provide control of alternating current to a highly inductive load?I am sorry to say this, but this circuit will die immeadiately if you turn it on.
An inductive load tries to have a constant current, so the current keeps flowing even if the IGBTs are in the off-state. Thus inducing an overvoltage which will destroy the switches.
The way i see it you want to build a stepdown converter with fixed dutycycle so read about stepdown coverters and build it for one polarity, then think about how to incorporate the other halfwave. Just one step at a time after you actually understand what you are doing
Re: Bidirectional IGBT AC switch?
Sulaiman, Fri Oct 21 2016, 03:40PM
I suggest that ease of dying from transients in high power circuits goes
thyristor, triac, bjt, igbt, mosfet.
Sulaiman, Fri Oct 21 2016, 03:40PM
I suggest that ease of dying from transients in high power circuits goes
thyristor, triac, bjt, igbt, mosfet.
Re: Bidirectional IGBT AC switch?
Kizmo, Thu Oct 27 2016, 08:03AM
This is how i would do it :)
Kizmo, Thu Oct 27 2016, 08:03AM
This is how i would do it :)
Re: Bidirectional IGBT AC switch?
Kolas, Fri Oct 28 2016, 10:53PM
Hehe that's actually a pretty nifty idea. Thanks for the feedback guys.
Kolas
Kolas, Fri Oct 28 2016, 10:53PM
Hehe that's actually a pretty nifty idea. Thanks for the feedback guys.
Kolas
Re: Bidirectional IGBT AC switch?
anokata, Sat Dec 03 2016, 06:36PM
Hi. May be useful to you. IGBT transistor in this circuit also work fine.
anokata, Sat Dec 03 2016, 06:36PM
Hi. May be useful to you. IGBT transistor in this circuit also work fine.
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