The invention relates to a power unit having a housing (1) in which at least one power electronics module (2), preferably a plurality of power electronics modules (2) is or are housed, positioned on a plane of the housing (1), the or each power electronics module (2) comprising at least one power electronics component (16), and being connected to at least one electronic control board (6) by at least one connection element (5). The power unit is characterized in that it comprises at least one member (7, 8) supporting the at least one electronic control board facing the power module (2) over at least one expanse of the board (6), the support member being the beam (7, 8) substantially parallel to said plane of the housing.