In some Shul's that I have prayed I have noticed that during Kabalos Shabbos and Yekum Purkan the Chazzan stands at the Bima instead of the Amud. What is the reason for those Shul's that do it this way?
Rabbi J Sacks in the Koren Siddur refers to the gemoro Shabbos 119a where Rabbi Chanino stood on the eve of Shabbos and said, “Come let us go and welcome the Shabbos Queen” etc. The mystics in Safed in the late sixteenth century developed the idea of saying extra psalms to welcome the Shabbos. Rabbi Shlomo Alkabets compose the song, “Lecho Dodi”. This developed into the Kabollas Shabbos service that we now have.
Rabbi Sacks writes that to emphasize the non-statutory character of Kabollas Shabbos, the custom in some synagogues is to recite it from the bima and not from the amud (lectern).
There is an extensive discussion of Yekum Purkan in Rivevos Efraim 6 (455) ; so far I did not find that it discusses saying it from the bimoh.
I suggest it is said from the bimoh for convenience as that is the location of the sefer torah which the chazzan will shortly return to the Ark.