Power unit and power conversion apparatus having the same

1. A power unit, comprising:

a power module which is configured by a power conversion switching element, the power module including a first side having gate pins connected to a board, and a second side to which main busbars are connected;

cooling modules which are disposed on both surfaces of the power module, respectively;

capacitor modules which are disposed on outer surfaces of the cooling modules, respectively, and have capacitors that are electrically connected to the main busbars through connecting busbars, respectively;

a coolant supply pipe which is connected to one end portion of each of the cooling modules to supply a coolant to the cooling module; and

a coolant discharge pipe which is connected to another end portion of each of the cooling modules to discharge a coolant discharged from the cooling module,

wherein the capacitor module includes:

a substrate which is disposed on one surface of the cooling module;

the capacitors which are disposed on a surface of the substrate opposite to the surface in contact with the cooling module, and are electrically connected to the main busbars through the connecting busbar; and

a capacitor housing which is formed along an outer edge of the substrate such that the substrate and the capacitor are disposed in the capacitor housing, and is in contact with the cooling module.

2. The power unit of claim 1 , wherein:

coolant channels, which are connected between the coolant supply pipe and the coolant discharge pipe, are formed in the cooling module, and

a coolant passing through the coolant channel absorbs heat generated from the power module.

3. The power unit of claim 2 , wherein the coolant supply pipe and the coolant discharge pipe extend side by side at both sides of the power module.

4. The power unit of claim 1 , wherein the capacitor housing and the cooling module are joined together.

5. The power unit of claim 1 , wherein the capacitor housing is made of a non-conductive material.

6. The power unit of claim 1 , wherein:

the main busbars and the capacitors are electrically connected to one another through the connecting busbars, and

the connecting busbars are formed along an outer surface of the capacitor housing opposite to an inner surface of the capacitor housing which faces the cooling module so as to electrically connect the main busbars and the capacitors.

7. The power unit of claim 1 , wherein:

a protrusion is formed at one side of an outer surface of the capacitor housing disposed to correspond to one surface of the power module, and

a groove, which has a shape corresponding to a shape of the protrusion and is positioned to correspond to the protrusion, is formed at one side of an outer surface of the capacitor housing disposed to correspond to the other surface of the power module.

8. The power unit of claim 1 , wherein: the power module and the cooling module are joined together.

9. The power unit of claim 1 , wherein: the main busbars include:

a positive DC busbar which is connected to a positive direct current power source;

a negative DC busbar which is connected to a negative direct current power source; and

a phase busbar which is disposed at a preset interval from the positive and negative DC busbars.

10. A power conversion apparatus wherein the power units according to claim 1 are stacked in series such that the connecting busbars of the neighboring capacitor modules are in contact with one another, the coolant supply pipes are connected to one another along a single axis, and the coolant discharge pipes are connected to one another along a single axis.

11. The power conversion apparatus of claim 10 , further comprising:

elastic members which support the power units at both ends of the power units so as to maintain a state in which the power units are stacked.

12. A motor driving system comprising:

the power conversion apparatus according to claim 10 ;

a battery which supplies power to the power module;

a board which transmits a control signal to the gate pins of the power module; and

a motor which generates rotational force by using power supplied from the power module.

13. A hybrid vehicle comprising;

the motor driving system according to claim 12 ; and

an internal combustion engine which generates rotational force together with the motor.

14. A fuel cell vehicle comprising:

the motor driving system according to claim 12 ; and

a fuel cell which is electrically connected to the battery and produces electricity through a chemical reaction.

15. An electric vehicle which moves by using rotational force generated by the motor driving system according to claim 12 .