Electric power converter

1. An electric power converter, comprising:

a cooler, which includes a passage through which a cooling medium flows; and

at least two heat generating bodies, which are dispersedly arranged on upper and lower surfaces of the cooler to be cooled by the cooler,

wherein the passage from a cooling medium inlet to a cooling medium outlet of the cooler includes:

an upstream cooling portion and a downstream cooling portion which cools the at least two heat generating bodies;

an upstream distribution portion located on a cooling medium inlet side;

a downstream distribution portion located on a cooling medium outlet side;

connecting portions which are disposed proximate respective side surfaces of the cooler and connect the upstream cooling portion and the downstream cooling portion; and

a partition portion which partitions the upstream cooling portion and the downstream cooling portion, and the upstream distribution portion and the downstream distribution portion, and

wherein the passage is connected so that the cooling medium flows in order of the upstream distribution portion, the upstream cooling portion, the connecting portion, the downstream cooling portion, and the downstream distribution portion,

the cooling medium splits into two flows from the upstream distribution portion, in respective opposing directions toward each of the respective side surfaces, to form the upstream cooling portion proximate the upper surface,

each of the two flows enters a corresponding connecting portion and a corresponding downstream cooling portion, and

the two flows join each other onto the downstream distribution portion proximate the lower surface.

2. An electric power converter according to claim 1 , wherein an allowable temperature of the heating element mounted on the downstream cooling portion is higher than an allowable temperature of the heating element mounted on the upstream cooling portion.

3. An electric power converter according to claim 1 , wherein the heating element mounted on the downstream cooling portion comprises a wide bandgap semiconductor.

4. An electric power converter according to claim 3 , wherein the wide bandgap semiconductor comprises at least one element selected from the group consisting of: silicon carbide; a gallium nitride-based material; and diamond.

5. An electric power converter according to claim 1 , wherein an amount of heat generated by the heating element mounted on the upstream cooling portion is larger than an amount of heat generated by the heating element mounted on the downstream cooling portion.

6. An electric power converter according to claim 1 , wherein the heating element mounted on the upstream cooling portion comprises a switching element.

7. An electric power converter according to claim 1 , wherein the heating element mounted on the downstream cooling portion comprises a converter configured to control a supply voltage.

8. An electric power converter according to claim 1 , wherein the heating element mounted on the upstream cooling portion comprises a semiconductor module to be used in a power converter configured to control a motor for driving a vehicle.

9. An electric power converter according to claim 1 , wherein a passage cross sectional area of the connecting portion and passage cross sectional areas of the upstream cooling portion and the downstream cooling portion are substantially equal.

10. An electric power converter according to claim 1 , wherein a passage cross sectional area of the upstream distribution portion is reduced farther from the cooling medium inlet side, and a passage cross sectional area of the downstream distribution portion is increased closer to the cooling medium outlet side.

11. An electric power converter according to claim 1 , wherein the cooler comprises:

cooling fins integrated with heating element mounting plates; and

a passage housing integrated with the partition portion,

wherein the cooling fins integrated with the heating element mounting plates are made of aluminum and processed by extrusion, and then a surface on which the at least two heat generating bodies are not mounted is processed by one of cutting and forging so that parts of the at least two heat generating bodies are arranged on a plane including at least one of the connecting portion, and the upstream distribution portion and the downstream distribution portion, and

wherein the at least one of the connecting portion, and the upstream distribution portion and the downstream distribution portion has a part of a function of the upstream cooling portion and the downstream cooling portion.

12. An electric power converter according to claim 1 , wherein the cooler comprises:

cooling fins integrated with heating element mounting plates; and

a passage housing integrated with the partition portion,

wherein a through hole formed in the partition portion constitutes the connecting portion, and a concavity and convexity formed in the partition portion constitutes the upstream distribution portion and the downstream distribution portion, and

wherein at least one of the cooling fins integrated with the heating element mounting plates and the passage housing integrated with the partition portion are bonded by one of welding and brazing.

13. An electric power converter according to claim 1 , wherein the cooler comprises heating element mounting plates, cooling fins, and the partition portion,

wherein a through hole formed in the partition portion constitutes the connecting portion, and

wherein the heating element mounting plates, the cooling fins, and the partition portion are bonded by brazing to constitute a part of the passage.