三个委员会成员：three of the committee members?three members of the committee?

three committees。
来源：Recently ENTSO-E’s Assembly approved to create a fourth Committee on Research & Development, besides its three existing Committees on System Development, System Operations and Market, to ensure effective implementation of its mandate in the area of R&D and to correspond to the greater emphasis of the EU on electric grids.

正three committee members
简洁明了，符合native speaker的习惯

应该是 three members of the committee.