Ingela is a variant of Angela in some countries, like German (from engel), but means "Ing's protection" or "guarded by Ing" in Scandinavian/Old Norse. Ing, the Norse goddess, was also the foundation for Ingrid, meaning "Ing's beauty." Ingela dates back to at least 1692 in Northern Europe, but world wide may date as far back as any record of Angela. There were no babies named Ingela in 2011 or 2010, and my guess is you won't find more than a small handful of Ingela's in U.S. records of birth, and even White Pages tells us there are only 118 in the U.S.
Ingela Olsson was a Swedish actress from the 90's, Ingela Forsman a popular lyricist, and Ingela Klemetz was responsible for an art gallery exhibit on Northern Women in Chanel. There was also Ingela Gathenhielm, known as the "Shipping Queen," a Swedish privateer and pirate during the 1700's with her husband Lars. There actions were sanctioned by King Charles XII of Sweden.