Re: [TCML] IGBT variac dimmer?

[dave pierson <dave_p@xxxxxxxxxxx>]

> IGBTs (or fets or transistors) could definitely do the job of a
> variac, that is to produce a sinusoidal voltage at mains frequency of
> variable magnitude. One circuit topology would be to rectify the mains
> AC then use an IGBT half bridge to produce the desired sinusoid.
    requiring significant heat sinking.
    8)>> 
> You could do more with the IGBTs as well because you would be able to
> vary the magnitude and frequency of your sinusoidal out put, or even
> produce non sinusoidal functions like ramp or square waves these could
> produce some interesting results for Tesla coil outputs.
> 
> As for protecting from over load there are a host of solid state
> methods for protecting the switching devices from this.
> 
> As an aside I believe that the humble dimmer switch contains a
> thyristor (SCR) so the wave form which it produces is a chopped
> version of the mains AC, not a sinusoid of lower magnitude.
    I suspect, more commonly, a triac
    (think: bidirectional SCR.).  The comment on
    chopped/distorted sine is well made.

    best
     dwp
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