Power converter

1. A power converter comprising:

a semiconductor module incorporating therein a semiconductor element constituting a power converter circuit;

a smoothing capacitor configured to smooth a direct-current voltage applied to the semiconductor module;

a pair of positive and negative busbars configured to electrically connect the semiconductor module and the smoothing capacitor, the positive and negative busbars being arranged to face each other with a predetermined space therebetween; and

a discharge resistor connected in parallel with the smoothing capacitor via the positive and negative busbars and configured such that an electrical charge stored in the smoothing capacitor flows through the discharge resistor as a discharge current,

the positive and negative busbars being interposed between the discharge resistor and the smoothing capacitor, wherein:

the smoothing capacitor comprises positive and negative terminals;

the positive busbar is fastened to the positive terminal of the smoothing capacitor;

the negative busbar is fastened to the negative terminal of the smoothing capacitor; and

the positive and negative terminals of the smoothing capacitor are configured to support the positive and negative busbars and the discharge resistor.

2. The power converter according to claim 1 , further comprising:

an insulator member interposed between the positive and negative busbars.

3. The power converter according to claim 1 , wherein:

the smoothing capacitor is provided as a discrete component being unintegrated with the positive and negative busbars; and

the smoothing capacitor includes a pair of positive and negative terminals that are fastened to the respective positive and negative busbars.

4. The power converter according to claim 1 , further comprising:

a mount base to which the positive and negative busbars are mounted,

wherein the mount base is interposed between the discharge resistor and the positive and negative busbars.

5. The power converter according to claim 4 , wherein:

the discharge resistor is mounted to the mount base.

6. The power converter according to claim 1 , further comprising:

a cooling mechanism arranged to cool the semiconductor module.

7. The power converter according to claim 6 , wherein:

each of the positive and negative busbars has a thickness;

the cooling mechanism is arranged such that at least a part of the cooling mechanism is adjacent to the discharge resistor and is closer to the discharge resistor than to the capacitor in a direction of the thickness of each of the positive and negative busbars; and

the cooling mechanism is configured such that a coolant flows through at least the part of the cooling mechanism.

8. The power converter according to claim 1 , further comprising:

a metallic housing that houses the semiconductor module, the cooling mechanism, the discharge resistor, the smoothing capacitor, and the positive and negative busbars,

wherein:

the housing is comprised of a plurality of walls;

at least one of the walls of the housing is in thermal contact with the cooling mechanism; and

the discharge resistor is arranged to be sandwiched between the cooling mechanism and at least one of the walls of the housing.

9. The power converter according to claim 6 , wherein:

the positive and negative busbars and the discharge resistor are mounted to the mount base so as to constitute an assembly; and

the positive and negative terminals of the smoothing capacitor are configured to fixedly support the assembly of the positive and negative busbars, the discharge resistor, and the mount base.

10. The power converter according to claim 6 , further comprising:

a metallic bracket interposed between the mount base and the discharge resistor and configured to mount the discharge resistor to the mount base.

11. The power converter according to claim 1 , further comprising:

a pair of wires that electrically connect the discharge resistor and the respective positive and negative busbars.

12. The power converter according to claim 1 , wherein:

the discharge resistor is located above the positive and negative busbars in a direction opposite to a direction of gravitational force; and

the smoothing capacitor is located below the positive and negative busbars in the direction of gravitational force.