Re: Phase chopping.. bad?

From: Joel Kolstad (JKolstad71HatesSpam_at_Yahoo.Com)
Date: 10/08/04 

Date: Fri, 8 Oct 2004 11:54:11 -0700

<pbdelete@spamnuke.ludd.luthdelete.se.invalid> wrote in message
news:4166ce3a$0$175$cc7c7865@news.luth.se...
> Joel Kolstad <JKolstad71HatesSpam@yahoo.com> wrote:
>><pbdelete@spamnuke.ludd.luthdelete.se.invalid> wrote in message
>>news:416559ad$0$180$cc7c7865@news.luth.se...
>>> Is chopping of a 240V rms AC-sinewave with ibgt (or mosfet..) with
>>> 5-30 kHz pwm and filter it to regulate power to pure resistance load a
>>> bad
>>> idea?
>
>>There is very similar to how factor correction is done is power
>>supplies --
>
> factor correction -> you mean power factor correction? (W vs VA etc..)

Yes, sorry about dropping the word there.

> If so it's possible to build a adjustable powerfactor correction circuit
> by an oversized capacitor that is connected through pwm cycles at varying
> duty cycle?
> And thus one can power correct a inductive load for use with ibgt if
> needed?

Yep. Power factor correctoin is a popular research topic, and important
enough commercially that you'll find the likes of On-Semi and others make
power factor correction chips. (Note that if you plan to do the same thing
and actually sell a product, there are a few patents out there to be aware
of. :-( )

I can't comment on the rest of your post in that I don't have any real
design experience with off-line (120V/240V) supplies other than having used
them and occasionally paying attention when they were discussed as part of
broader topic coverage (such as low voltage switchers, that I have design
experience with).

---Joel

Relevant Pages

  • hp spec...was Re: Motorcycle Horsepower Question
    ... Net vs gross still refers to the output shaft of the _engine_, ... Surface Vehicle Standard ... Net Power Rating ... There are a bunch of other formulas for atmosphere correction, ...
    (rec.motorcycles)
  • Re: ABF power
    ... >> Without the above qualifying statements any power figure is totally ... The corrected figure has nothing whatsoever to do with engine or chassis dynos and obviously both cannot be compared. ... A chassis dyno is just as accurate and measures as ir says rear wheel Hp CORRECTED to a standard pressure and temperature if you want it to. ... Correction factors have absolutely nothing to do with the difference between the two types of dyno or measuring "flywheel" or engine power on a chassis dyno ...
    (uk.rec.cars.modifications)
  • Re: PowerwoRx E3... Save money and energy Go GREEN
    ... Like low cholesterol ... Low power factor is usually a result of a number of induction motors operating at the same time, ... PF correction may be accomplished by synchronous motors or capacitor banks. ... Those industrial/commercial customers that may have PF issues are metered by the POCO with PF meters. ...
    (alt.home.repair)
  • Re: Question relating to power factors and old welder
    ... The power factor on the unit will be horrific being mostly a reactive load ... could fit a cap across that tap to neutral. ... I could fit a cap across the 440 volt tap to neutral and still feed on ... Power factor correction at idle is OK because the ...
    (uk.rec.models.engineering)