Method for interconnecting at least two electronic power modules of a polyphase rotary electric machine together, and for interconnecting said power modules with determined components of said polyphase rotary electric machine, said power modules comprising a substrate comprising a layer composed of a first plurality of conductive tracks on which power semiconductor components and integrated electronic control circuits for controlling these components that are electrically connected by said conductive tracks are implemented, characterized in that it comprises an initial phase comprising a step consisting of depositing said substrates (51 to 53) in open cavities (41 to 43) on a face referred to as the upper face of a carrier member so as to be inscribed in a first plane in space, a subsequent phase of producing said interconnections comprising at least the following steps: - a step of producing first interconnection means forming a planar connector comprising at least one layer composed of a second plurality of conductive tracks borne by at least one wafer, referred to as the lower wafer, made of an insulating material, so as to form a network of electrical connections of predetermined configuration; - a step of producing a plurality of connecting elements in each of said power modules (51 to 53) composed of filiform components made of a conductive material, of determined geometric conformations, and their electrical connections, through ultrasonic welding or soldering, on a first end referred to as the lower end, to said conductive tracks of the substrates (51 to 53) and/or to said power electronic components, so that they are inscribed in planes that are substantially orthogonal to said first plane in space; - a step of producing recesses in at least said lower wafer of said planar connector, the spatial distribution of said recesses corresponding to the spatial distribution of said connecting elements; - a step of positioning said planar connector on top of said connecting elements, in a plane that is parallel to said first plane in space, so that the second ends, referred to as the upper ends, of said connecting elements may be brought into contact with said conductive tracks of said connector through said openings; and - producing electrical connections between said upper ends of said connecting elements and said conductive tracks through welding. - a step of producing first interconnection means forming a planar connector comprising at least one layer composed of a second plurality of conductive tracks borne by at least one wafer, referred to as the lower wafer, made of an insulating material, so as to form a network of electrical connections of predetermined configuration; - a step of producing a plurality of connecting elements in each of said power modules (51 to 53) composed of filiform components made of a conductive material, of determined geometric conformations, and their electrical connections, through ultrasonic welding or soldering, on a first end referred to as the lower end, to said conductive tracks of the substrates (51 to 53) and/or to said power electronic components, so that they are inscribed in planes that are substantially orthogonal to said first plane in space; - a step of producing recesses in at least said lower wafer of said planar connector, the spatial distribution of said recesses corresponding to the spatial distribution of said connecting elements; - a step of positioning said planar connector on top of said connecting elements, in a plane that is parallel to said first plane in space, so that the second ends, referred to as the upper ends, of said connecting elements may be brought into contact with said conductive tracks of said connector through said openings; and - producing electrical connections between said upper ends of said connecting elements and said conductive tracks through welding.