I work for a manufacturer of home lighting control systems and the TRIAC vs.
reverse phase dimming (or lagging edge dimming) has heated up in the past
few years.  CE approvals in Europe and other parts of the world test for
emmitted emissions and conducted emissions.  TRIAC dimmers need massive
amounts of filtering to pass CE.  Some of my clients claim that TRIAC
dimming is against code in some countries due to the high EMI output as they
turn on part way through the cycle. My previous company, Vantage Lighting
has a reverse phase dimmer that uses MOSFETS.  It is expensive and limited
to 6 amps per channel, and is very easily blown.  Of course they use 2
MOSFETs per dimmer. There are a number of commercial IBGT dimmers on the
market.  We've done some testing of IGBT's for dimming and they do run a
little hotter than TRIAC's and cost more.

Here is some info from a document I found on my computer.  I think it is
from an engineer in New Zealand by the name of Mike Pearce.  He has a PIC
design for a dimmer with code for both types of dimming.  If anyone wants
the files I can send them to you.



An IGBT driver turns the output ON at the zero cross point and turns

the output OFF part way through the cycle - this has really low

EMI properties and is one of the few methods allowed for phase control

in European countrys (i.e complies with EN55015 EMI standard).

Other countries are following suit for example New Zealand and Austrailia

are almost there (See AS/NZS 4051 and CISPR15 EMI Standards )

This method of dimming is audibly quiet, does not require extra filter

componets (If designed properly).It also has a better lamp life and can

control a wider range of lamps than the TRIAC method of dimming.









Reverse Phase Dimming or Reverse Phase control, does anyone has some
references?
I would use it for light control. I would be glad to see IGBT in such
circuit.
Thanks

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