Abstract: The invention refers to a heat transfer assembly for cooling an electronic power circuitry, said heat transfer assembly comprising a base member and at least one electronic power component in heat conductive contact for transferring heat to said base member, a heat transfer chamber adjoining said base member and being provided with fins extending from said base member into said heat transfer chamber for transferring heat to a flow of cooling medium extending through said heat transfer chamber and passing through spaces between said fins, said heat transfer assembly is designed such that said flow of cooling medium comprising an environment induced flow extending through said heat transfer chamber and entering said heat transfer chamber with respect to the direction of gravity in a lower section thereof and exiting from said heat transfer chamber with respect to said direction of gravity from an upper section thereof.