Method and apparatus for detecting state of relay

1. An apparatus for detecting a state of a relay, the apparatus comprising:

a voltage outputter configured to output a voltage having a different voltage value for each state of each of a plurality of relays configured to switch a connection between a battery and a load;

a controller configured to determine whether each of the plurality of relays is welded based on the voltage output from the voltage outputter; and

a voltage transmitter configured to transmit the voltage output from the voltage outputter to the controller and to adjust the voltage output from the voltage outputter to be a voltage that can be input to the controller,

wherein the plurality of relays comprise:

a first relay connected to an anode of the battery;

a second relay connected to a cathode of the battery; and

a third relay connected in series with an auxiliary resistance, with the series-connected third relay and auxiliary resistance being connected in parallel with the first relay,

wherein the voltage outputter comprises:

an operational amplifier; and

a plurality of resistances connected to an inverting terminal and a non-inverting terminal of the operational amplifier, and

the voltage outputter is further configured to output the voltage from an output terminal of the operational amplifier,

wherein the plurality of resistances comprises:

a first resistance connected between the inverting terminal and a point where the first relay and the third relay are connected to each other;

a second resistance connected between the inverting terminal and the output terminal of the operational amplifier;

a third resistance connected between the non-inverting terminal and an external power source;

a fourth resistance connected between the second relay and the non-inverting terminal; and

a fifth resistance connected between a ground and a point where the first relay, the third relay, and the first resistance are connected to each other.

2. The apparatus of claim 1 , wherein the voltage outputter is further configured to:

apply a voltage of the external power source to the first resistance, the second resistance, and the fifth resistance in response to the first relay through the third relay being in an OFF state; and

output, from the output terminal of the operational amplifier, a differential voltage between the voltage of the external power source and a voltage applied to the second resistance.

3. The apparatus of claim 1 , wherein the voltage outputter is further configured to:

apply a voltage of the external power source to the first through fifth resistances in response to the second relay being in an OFF state; and

output, from the output terminal of the operational amplifier, a differential voltage between a voltage applied to the fourth resistance and a voltage applied to the second resistance.

4. The apparatus of claim 1 , wherein the voltage outputter is further configured to:

apply a voltage of the battery and a voltage of the external power source to the first through fifth resistances and the auxiliary resistance in response to the second relay and the third relay being in an ON-state and the first relay being in an OFF-state; and

output, from the output terminal of the operational amplifier, a differential voltage between a voltage applied to the fourth resistance and a voltage applied to the second resistance.

5. The apparatus of claim 1 , wherein the voltage outputter is further configured to:

apply a voltage of the battery and a voltage of the external power source to the first through fourth resistances in response to the first relay and the second relay being in an ON-state and the third relay being in an OFF-state; and

output, from the output terminal of the operational amplifier, a differential voltage between a voltage applied to the fourth resistance and a voltage applied to the second resistance.

6. The apparatus of claim 1 , wherein a voltage value of the external power source is equal to a voltage value of the battery.

7. The apparatus of claim 1 , further comprising an isolator configured to electrically separate the voltage transmitter and the controller from each other;

wherein the voltage transmitter is further configured to transmit the voltage output from the voltage outputter to the controller via the isolator.

8. The apparatus of claim 1 , wherein the controller is further configured to determine whether each of the plurality of relays is welded by comparing the voltage output from the voltage outputter to predetermined reference information.

9. The apparatus of claim 1 , wherein the controller is further configured to control each of the plurality of relays to switch a connection between each of the plurality of relays and the voltage outputter; and

the voltage outputter is further configured to output the voltage having the different voltage value for each state of each of the plurality of relays based on the connection between each of the plurality of relays and the voltage outputter.

10. The apparatus of claim 1 , wherein the controller is further configured to transmit information on a welding state of each of the plurality of relays outside the apparatus.

11. The apparatus of claim 1 , wherein the state of each of the plurality of relays includes an ON-state and an OFF-state.

12. The apparatus of claim 1 , wherein the state of each of the plurality of relays includes a state where all of the plurality of relays are in an OFF-state.

13. The apparatus of claim 1 , wherein the voltage outputter is configured to output the voltage regardless of whether all of the plurality of relays are in an OFF-state.

14. A method of detecting a state of a relay, the method comprising:

detecting a voltage having a different voltage value for each state of each of a plurality of relays configured to switch a connection between a battery and a load;

transmitting the detected voltage to a controller;

determining whether each of the plurality of relays is welded based on the detected voltage; and

adjusting the voltage output from the voltage outputter to be a voltage that can be input to the controller,

wherein the plurality of relays comprise:

a first relay connected to an anode of the battery;

a second relay connected to a cathode of the battery; and

a third relay connected in series with an auxiliary resistance, with the series-connected third relay and auxiliary resistance being connected in parallel with the first relay,

wherein the voltage outputter comprises:

an operational amplifier; and

a plurality of resistances connected to an inverting terminal and a non-inverting terminal of the operational amplifier, and

the voltage outputter is further configured to output the voltage from an output terminal of the operational amplifier,

wherein the plurality of resistances comprises:

a first resistance connected between the inverting terminal and a point where the first relay and the third relay are connected to each other;

a second resistance connected between the inverting terminal and the output terminal of the operational amplifier;

a third resistance connected between the non-inverting terminal and an external power source;

a fourth resistance connected between the second relay and the non-inverting terminal; and

a fifth resistance connected between a ground and a point where the first relay, the third relay, and the first resistance are connected to each other.

15. The method of claim 14 , wherein the determining comprises determining whether each of the plurality of relays is welded by comparing the detected voltage to predetermined reference information.

16. A non-transitory computer-readable storage medium storing a program comprising instructions to cause a computer to perform the method of claim 14 .