Abstract: A power conversion apparatus includes plural press-pack power semiconductor devices; plural thermal and electric conducting blocks provided among the plural press-pack power semiconductor devices; and plural bus bars provided among the plural press-pack power semiconductor devices and the plural thermal and electric conducting blocks to form a first column that is clamped under a predetermined mechanical force. The plural bus bars are directly pressed in the first or more columns for electrical connection, at least one of the press-pack power semiconductor devices is sandwiched between two thermal and electrical conducting blocks, and at least one of the bus bars is sandwiched between two thermal and electric conducting blocks. A method for assembling the power conversion apparatus is also provided. The apparatus and the method can provide optimum heat transfer for press-pack power semiconductor devices and minimum commutation loss and stress.

Abstract: A method and cooling system that cools a power stack in a power conversion apparatus. The liquid cooling system includes a first cooling stage that includes first cooling components, wherein the first cooling components are connected to form parallel cooling branches; a mixing manifold configured to be fluidly connected to the parallel cooling branches so that cooling liquid streams from the parallel cooling branches are mixed in the mixing manifold; and a second cooling stage that includes second cooling components, and the second cooling stage is connected in series with the first cooling stage in terms of a cooling liquid that flows through the cooling system.