Apparatus for diagnosing relay contact of electric vehicle and method thereof

1. A method of diagnosing a relay contact of an electric vehicle, the method comprising:

measuring a first voltage input from a high-voltage battery to an inverter;

comparing the first voltage with a second voltage output through the high-voltage battery;

identifying a detection time point of the first voltage when the first voltage is greater than the second voltage; and

determining whether a high-voltage relay, which intermits an output voltage of the high-voltage battery, is malfunctioned based on the identified detection time point.

2. The method of claim 1 , wherein the measuring of the first voltage is performed at a time point of ignition-on of the electric vehicle, and

the detection time point is a lapse time from the time point of ignition-on to the time point at which the first voltage is detected.

3. The method of claim 1 , further comprising:

comparing the detection time point with a time point of stabilizing a voltage input to the inverter when the detected time point is identified.

4. The method of claim 3 , wherein the determining of the malfunction of the high-voltage relay comprises:

determining that the high-voltage relay is normal when the detection time point occurs on or after the stabilization time point.

5. The method of claim 3 , wherein the determining of the malfunction of the high-voltage relay comprises:

determining that a fusion is caused in the high-voltage relay when the detection time point occurs before the stabilization time point.

6. The method of claim 5 , further comprising:

storing diagnosis information about the fusion of the high-voltage relay when the fusion of the high-voltage relay is determined.

7. The method of claim 5 , further comprising:

displaying diagnosis information about the fusion of the high-voltage relay when the fusion of the high-voltage relay is determined.

8. The method of claim 1 , further comprising:

measuring again the first voltage input from the inverter after a predetermined time is elapsed when the first voltage is lower than the second voltage.

9. An apparatus for diagnosing a relay contact of an electric vehicle, the apparatus comprising:

a high-voltage battery serving as a main power source;

an inverter receiving a DC (direct current) electrical power from the high-voltage battery and driving a motor by changing a phase of the DC electrical power; and

a high-voltage relay between the high-voltage battery and the inverter, the high-voltage relay intermitting the DC electrical power output through the high-voltage battery,

wherein the inverter determines whether the high-voltage relay is malfunctioned based on a time point at which a DC link voltage value according to the supplying of the DC electrical power is equal to or greater than a voltage value of the high-voltage battery and intermits a power input to the motor according to a diagnosis result.

10. The apparatus of claim 9 , wherein the inverter comprises:

a DC link input unit receiving the DC link voltage output through the high-voltage battery;

a main control unit receiving a DC link voltage value input through the DC link input unit and diagnosing whether the high-voltage relay is malfunctioned based on a time point at which the DC link voltage value is equal to or greater than a voltage value of the high-voltage battery and a time point at which the DC link voltage is stabilized; and

a motor control unit selectively supplying an electrical power to the motor according to a diagnosis result of the main control unit.

11. The apparatus of claim 10 , wherein the main control unit detects the first voltage at a time point of ignition-on of the electric vehicle and diagnoses whether the high-voltage relay is malfunctioned based on a lapse time from the time point of ignition-on to a time point at which the DC link voltage having a value equal to or greater than the voltage value of the high-voltage battery is detected.

12. The apparatus of claim 11 , wherein the main control unit determines that the high-voltage relay is normal when the detection time point occurs on or after the stabilization time point, and determines that a fusion is caused in the high-voltage relay when the detection time point occurs before the stabilization time point.

13. The apparatus of claim 12 , wherein the inverter further comprises:

a memory storing diagnosis information about the fusion of the high-voltage relay when the fusion of the high-voltage relay is determined; and

a display unit displaying diagnosis information about the fusion of the high-voltage relay when the fusion of the high-voltage relay is determined.