Jump to content
Electronics-Lab.com Community

230V/1000W AC dimmer


Buddi
 Share

Recommended Posts

Hi,

I'm working on a project where I'm desigining an AC dimmer (230V/1000W) with Electro magnetic compatibility. My idea is to involve IGBTs or MOSFETs instead of more conventional triacs...

Do you think that this would be a good idea?

If you have prior experiences please share...

Regds,
Buddi

Link to comment
Share on other sites

Hi Buddi,
Welcomr to our forum. ;D
A triac is made for AC. They are used in light dimmers to quickly switch the power on and off and they dim by changing the duty-cycle. Because they quickly switch, they don't get hot. The quick switching is bad for an electro magnetic load.

IGBT's and Mosfets work on DC so two or an additional rectifier bridge are needed to switch AC, then it will work exactly like a triac circuit.

I hope you are not thinking of using the IGBT's or Mosfets as a linear resistance. Then they will quickly overheat and fail.

Link to comment
Share on other sites

Thnx very much...

This is one idea that I intend to use as a benchmark.

http://johboh.csbnet.se/____BINBOSFAX001.reedbusiness.com__c$__Program%20Files__RightFax__Gateway__IN__A628c412e-b8cf-4efe-a2bd-d6c8b9a99ada.TIF

There is some extensive heat dissipation as you have mentioned... and it seems there is some problem with gate triggering and the bulb flickers instead of steady dimming...I used IRF 540 MOSFET....

Buddi

Link to comment
Share on other sites

Guys,

I think I foud something...I did some analysis with the oscilloscope and found out that the cap. and the R6, R5 resistors that should determine the output does not work properly... then i did a slight modification by interchanging the R5 and R6 and now the dimmer is working...  :D

Now two small things to sort out...

1. When I vary the variable resistor the illuminance is increaesd and right at the very end there is a slight dimming that occurs after the bulb has reached the full illuminance...

2. There is a slight flickering of the output when put to the full power 

What do you guys think of these...???

Buddi

Link to comment
Share on other sites

that is something that i also couldnt understand... but it worked... ???
the circuit didnt work until i decided to put 2 vaiable resistors for both R5 and R6 just to test with different values...

And now I have left the circuit as that... yep, it cannot make any different theoritically, but it did...

Buddi

Link to comment
Share on other sites

That may be the reason then...thx for showing it to me...
Anyway as I mentioned it has some issues still...

1. Very visible flickering once the bulb is given the full power
2. Limited dimming range: The bulb dims...but I expect it to dim much more when I vary the resistance...

I'm trying to find a way control the level of gate

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...