An assembly comprising a power device and a cooling plate which overlies the power device for heat transfer therebetween; the power device comprising: a plurality of power switching components including at least a first power switching component and a second power switching component; wherein each of the power switching components is configured to dissipate heat to the cooling plate; the cooling plate comprising: a plurality of cooling zones overlying and aligned with the respective power switching components for heat transfer, including first and second cooling zones corresponding to the first and second power switching components; and a flow channel for a cooling flow, extending between an inlet and an outlet through each of the cooling zones; wherein a geometric parameter of the flow channel that at least partly determines heat transfer in a respective cooling zone differs between the first and second cooling zones for improved heat transfer in the first cooling zone relative to the second cooling zone, characterised in that: in the first cooling zone, there is a flow acceleration protrusion extending into the flow channel configured to locally accelerate the cooling flow by locally reducing the hydraulic diameter or the cross sectional area of the flow channel, and the flow acceleration protrusion is fastened to or configured to fasten to the first power switching component. the power device comprising: a plurality of power switching components including at least a first power switching component and a second power switching component; wherein each of the power switching components is configured to dissipate heat to the cooling plate; the cooling plate comprising: a plurality of cooling zones overlying and aligned with the respective power switching components for heat transfer, including first and second cooling zones corresponding to the first and second power switching components; and a flow channel for a cooling flow, extending between an inlet and an outlet through each of the cooling zones; a plurality of cooling zones overlying and aligned with the respective power switching components for heat transfer, including first and second cooling zones corresponding to the first and second power switching components; and a flow channel for a cooling flow, extending between an inlet and an outlet through each of the cooling zones; wherein a geometric parameter of the flow channel that at least partly determines heat transfer in a respective cooling zone differs between the first and second cooling zones for improved heat transfer in the first cooling zone relative to the second cooling zone, characterised in that: in the first cooling zone, there is a flow acceleration protrusion extending into the flow channel configured to locally accelerate the cooling flow by locally reducing the hydraulic diameter or the cross sectional area of the flow channel, and the flow acceleration protrusion is fastened to or configured to fasten to the first power switching component. in the first cooling zone, there is a flow acceleration protrusion extending into the flow channel configured to locally accelerate the cooling flow by locally reducing the hydraulic diameter or the cross sectional area of the flow channel, and the flow acceleration protrusion is fastened to or configured to fasten to the first power switching component.