Apparatus for diagnosing relay in vehicle obc, method therefor, and battery charging apparatus including same

A method for diagnosing a relay circuit unit in a vehicle on-board charger (OBC), the method comprising:

• measuring phase-specific voltages for AC inputs to the relay circuit unit by using first to third voltage sensors;
• measuring line voltages for AC outputs from the relay circuit unit by using fourth and fifth voltage sensors;
• and
• diagnosing the relay circuit unit, based on the phase-specific voltages measured by the first to third voltage sensors and based on the line voltages measured by the fourth and fifth voltage sensors.

A battery charging apparatus comprising:

• an input circuit comprising a relay circuit unit located in a vehicle on-board charger (OBC), wherein the relay circuit unit comprises a plurality of relays;
• and
• a relay diagnosis unit configured to diagnose the relay circuit unit,
• wherein the relay diagnosis unit comprises:
• a first voltage sensor configured to measure a first phase-specific voltage for a first AC input to the relay circuit unit,
• a second voltage sensor configured to measure a second phase-specific voltage for a second AC input to the relay circuit unit,
• a third voltage sensor configured to measure a third phase-specific voltage for a third AC input to the relay circuit unit,
• a fourth voltage sensor configured to measure a first line voltage for a first AC output from the relay circuit unit,
• a fifth voltage sensor configured to measure a second line voltage for a second AC output from the relay circuit unit, and
• a diagnosis module configured to diagnose the relay circuit unit, based on the phase-specific voltages measured by the first to third voltage sensors and based on the line voltages measured by the fourth and fifth voltage sensors.