Cooling system for a power module

Abstract

A cooling system for a power module (or some other power electronics device) is described, the cooling system having a closed flow path for circulating a cooling fluid, the flow path having a pressure that is reduced to below atmospheric pressure. The cooling fluid is circulated along the flow path to provide cooling of the power module. The flow path is delimited from the exterior environment by a space provided between the flow path and the exterior environment, said space being sealed off from the cooling flow path, and said space being sealed off towards the exterior environment. The flow path has a pressure below atmospheric pressure and the space between the flow path and the exterior environment is evacuated and typically has a pressure lower than the pressure in the flow path.

What is claimed is: 
     
         1 . A cooling system for a power electronics device, the cooling system comprising: a closed flow path for circulating a cooling fluid; means for circulating the fluid along the flow path to provide cooling of the power electronics device; and a condenser, wherein:
 said cooling fluid is passed to the condenser after having passed the power electronics device and the cooling fluid is passed to the power electronics device after having passed the condenser;   the flow path has a pressure that is reduced to below a pressure prevailing in an exterior environment; and   the flow path is delimited from the exterior environment by a space provided between the flow path and the exterior environment, said space being sealed off from the flow path, said space being sealed off from the exterior environment, and said space being at least partially evacuated.   
     
     
         2 . The cooling system according to  claim 1 , wherein said cooling fluid is based on water. 
     
     
         3 . The cooling system according to  claim 1 , wherein the space is sealed off from the exterior environment and is sealed off from the flow path by gaskets. 
     
     
         4 . The cooling system according to  claim 1 , wherein the space has a pressure below the pressure of both the flow path and the exterior environment. 
     
     
         5 . The cooling system according to  claim 1 , further comprising a pump for reducing the pressure in the said space. 
     
     
         6 . The cooling system according to  claim 5 , wherein said pump is an injector pump. 
     
     
         7 . The cooling system according to  claim 6 , further comprising the provision of a secondary cooling fluid used to operate the injector pump. 
     
     
         8 . The cooling system according to  claim 7 , wherein the secondary cooling fluid is used to cool the cooling fluid provided in the closed flow path. 
     
     
         9 . A power module having a cooling system as claimed in  claim 1 . 
     
     
         10 . A method of using a cooling system to cool a power electronics device, the method comprising:
 passing a cooling fluid around a closed flow path from the power electronics device to a condenser of the cooling system and from the condenser to the power electronics device, wherein the flow path has a pressure that is reduced to below a pressure prevailing in an exterior environment; and   partially evacuating a space that is provided between the flow path and the exterior environment.   
     
     
         11 . The method according to  claim 10 , wherein the step of partially evacuating the space results in the space having a pressure below the pressure of both the flow path and the exterior environment. 
     
     
         12 . The method according to  claim 10 , further comprising the step of partially evacuating the said space using an injector pump. 
     
     
         13 . The method according to  claim 12 , wherein a secondary cooling fluid is provided to operate the injector pump. 
     
     
         14 . The method according to  claim 13 , wherein the secondary cooling fluid is used to cool the cooling fluid provided in the closed flow path. 
     
     
         15 . The method according to  claim 10 , wherein the cooling fluid is water-based.