17-04-2014, 12:58 PM
[u]Transformer Design[/u]
Transformer Design.pdf (Size: 1.97 MB / Downloads: 23)
Evaluate peak ac flux density
At this point, one should check whether the saturation flux density is
exceeded. If the core operates with a flux dc bias Bdc, then B + Bdc
should be less than the saturation flux density Bsat.
If the core will saturate, then there are two choices:
• Specify B using the Kg method of Chapter 14, or
• Choose a core material having greater core loss, then repeat
steps 1 and 2
Transformer design
Process is iterative because of round-off of physical number of
turns and, to a lesser extent, other quantities
Effect of proximity loss
– Not included in design process yet
– Requires additional iterations
Can modify procedure as follows:
– After a design has been calculated, determine number of layers in
each winding and then compute proximity loss
– Alter effective resistivity of wire to compensate: define
eff = Pcu/Pdc where Pcu is the total copper loss (including proximity
effects) and Pdc is the copper loss predicted by the dc resistance.
– Apply transformer design procedure using this effective wire
resistivity, and compute proximity loss in the resulting design.
Further iterations may be necessary if the specifications are not
met.