Electric power conversion device

1. An electric power conversion device comprising:

a cooler that includes

a flow path through which a refrigerant flows,

a first surface, and

a second surface opposite to the first surface in a thickness direction; and

a plurality of power modules including a first power module and a second power module, each of the plurality of power modules including

a semiconductor device configuring an upper arm circuit and a lower arm circuit, and

a first capacitor connected in parallel to the upper and lower arm circuits,

wherein:

in each of the plurality of power modules, the first capacitor and the semiconductor device are arranged in the thickness direction;

the first power module is arranged on the first surface of the cooler; and

the second power module is arranged on the second surface of the cooler.

2. The electric power conversion device according to claim 1 , wherein:

the cooler is a first cooler;

the flow path of the first cooler is a first flow path;

each of the plurality of power modules includes a second cooler that includes a second flow path connected to the first flow path;

the second flow path of the second cooler of each of the plurality of power modules is connected to the first flow path to return the refrigerant from the first flow path, via the second flow path, to the first flow path; and

in each of the plurality of power modules, the semiconductor device is placed on a first surface of the second cooler and the first capacitor is placed on a side opposite to the semiconductor device with respect to the second cooler, in the thickness direction.

3. The electric power conversion device according to claim 2 , wherein:

the first flow path is divided into an upstream region and a downstream region; and

the second flow path of the second cooler of each of the plurality of power modules connects the upstream region and the downstream region.

4. The electric power conversion device according to claim 2 , wherein in each of the plurality of power modules:

the second cooler has a heat transfer coefficient higher than the first cooler and is branched into two stages in the thickness direction;

the semiconductor device is sandwiched by the two branched stages of the second cooler; and

at least one of the two branched stages of the second cooler, the first capacitor is placed on a side opposite to the semiconductor device.

5. The electric power conversion device according to claim 4 , wherein in each of the plurality of power modules:

the semiconductor device includes a signal terminal;

a drive circuit of the semiconductor device is formed in a circuit board;

the first capacitor is placed on a side opposite to the semiconductor device at one of the two branched stages of the second cooler; and

the circuit board is placed on a side opposite to the semiconductor device at another of the two branched stages of the second cooler and is connected to the signal terminal.

6. The electric conversion device according to claim 1 , wherein:

in at least one of the plurality of power modules, the semiconductor device is closer to the cooler than is the first capacitor.

7. The electric power conversion device according to claim 1 , wherein:

for the cooler, a length in the thickness direction is shorter than a minimum length in a direction orthogonal to the thickness direction.

8. The electric power conversion device according to claim 1 , wherein:

the semiconductor device in each of at least a first part of the plurality of power modules configures an inverter; and

the electric power conversion device

further includes a second capacitor that is placed between a direct current power source and the first capacitor of each semiconductor device that configures the inverter, and

has a capacitance higher than a capacitance of the first capacitor.

9. The electric power conversion device according to claim 8 , wherein:

the second capacitor is placed on both of the first and second surfaces of the cooler.

10. The electric power conversion device according to claim 8 , wherein:

the cooler includes a notch portion that partitions a placement region of the second capacitor and a placement region of the plurality of power modules.

11. The electric power conversion device according to claim 8 , further comprising:

a reactor,

wherein:

each semiconductor device of a second part of the plurality of power modules configures a converter together with the reactor; and

the second capacitor and the reactor are arranged in one direction orthogonal to the thickness direction.

12. The electric power conversion device according to claim 11 , wherein:

the second capacitor and the reactor are arranged in a same direction as an arrangement direction of the plurality of power modules; and

in a direction orthogonal to the thickness direction and the arrangement direction, the second capacitor and the reactor face each of the plurality of power modules.

13. The electric power conversion device according to claim 11 , wherein:

the reactor includes a plurality of reactors;

the converter is a multi-phase converter connected to the plurality of reactors in parallel to each other; and

the plurality of power modules configuring the multi-phase converter and the plurality of reactors are placed on both of the first and second surfaces of the cooler.

14. The electric power conversion device according to claim 11 , wherein:

the plurality of power modules are placed on an upstream side of the flow path; and

the second capacitor and the reactor are placed on a downstream side of the flow path as compared with the plurality of power modules.

15. The electric power conversion device according to claim 3 , further comprising:

a heating element different from the plurality of power modules,

wherein:

at least one of the plurality of power modules and the heating element are arranged close to at least one of the first surface and the second surface of the first cooler;

the upstream region and the downstream region extend in an arrangement direction of the at least one of the plurality of power modules and the heating element;

the heating element is placed between the upstream region and the downstream region in the flow path; and

in a direction orthogonal to the arrangement direction, one lateral surface of the heating element is cooled by the upstream region and a surface opposite to the one lateral surface is cooled by the downstream region.