There are a number of things that can be designed in to a power converter to reduce the conducted and radiated emissions generated at full power.  The importance of good layout along with a suitable topology & control cannot be stressed highly enough by us.

Unfortunately you get none of this information in a typical app note for a control IC intended to drive a high power circuit.  (Power Integrations seem to do a better job than most).

We have had to develop solutions for reducing emissions and for filtering those that remain, for common and esoteric power topologies in use today, and have been doing this for 20 years.

We can apply proven remedies to a circuit before it is laid out to give much better RFI performance when built and tested (we have had schematics & layouts faxed to our engineers, marked these up and returned them to the client, and had the client passing conducted emissions one day later - with our changes incorporated)

We know what works and what doesn't, we automatically design flyback (& other) transformers for minimum common mode transference.  We specify the frequency performance of a common mode choke when we design one in.  EMC is a black art to some - but a known quantity to us.

If you want serious, no nonsense EMC development assistance for your power project - email us today.