My machine will connect to three phases power 208V, but some of my electronics in the machine need single phase 110V . Where I can find a convertor to take care that?
Are we to assume your 3-phase supply has no neutral ?
Here's a link to a website that gives various options, it appears as though your loading will be light enough just to use a transformer connected to two of the phases.
A standard (and cheap) 220 to 110V step-down transformer would probably do the job with no worries.
Although you will not quite get 110V, this is probably transformered down, rectified and smoothed anyway, so it's not gonna be a big deal.
edit: Cow beat me to it, and found a range of transformers fitted for the job...