On-board charger, vehicle including the same, and method of operating the on-board charger

1. A method of operating an on-board charger for charging a high voltage battery of an electrically-charged vehicle, comprising:

supplying a DC voltage converted from an AC voltage to the high voltage battery to perform a charging operation;

measuring an internal voltage of a DC EMI filter that is configured to remove noise of the DC voltage;

calculating a leakage current estimate based on the internal voltage; and

controlling the charging operation in accordance with the leakage current estimate,

wherein calculating the leakage current estimate comprises:

removing a high-frequency noise component from the internal voltage of the DC EMI filter;

performing a time derivative on the internal voltage to calculate a current per a unit capacitance; and

multiplying the current per a unit capacitance by a Y-capacitor coefficient to obtain the leakage current estimate.

2. The method of claim 1 , wherein supplying comprises:

removing noise of the AC voltage;

converting the AC voltage to the DC voltage; and

removing the noise from the DC voltage.

3. The method of claim 1 , wherein the internal voltage of the DC EMI filter is a voltage across a Y-capacitor included in the DC EMI filter.

4. The method of claim 1 , wherein the high-frequency noise component has a frequency band of about 1 kHz or more.

5. The method of claim 1 , wherein the Y-capacitor coefficient is a sum of capacitances of Y capacitors included in the DC EMI filter.

6. The method of claim 1 , wherein the controlling of the charging operation comprises:

temporarily stopping the charging operation when the leakage current estimate is higher than a protection level;

blocking a current path of a DC voltage side of the on-board charger;

restarting the charging operation when the leakage current estimate is equal to or lower than the protection level after a predetermined time elapses; and

terminating the charging operation when the leakage current estimate is higher than the protection level after the predetermined time elapses.

7. The method of claim 6 , wherein the temporarily stopping of the charging operation comprises transmitting a charge stop request to the high voltage battery.

8. The method of claim 6 , wherein the restarting of the charging operation comprises transmitting a charge restart request to the high voltage battery.

9. The method of claim 6 , wherein the temporarily stopping of the charging operation comprises increasing a failure count and further comprises:

comparing the failure count with a count upper limit after the blocking of the current path; and

terminating the charging operation when the failure count exceeds the count upper limit.

10. An on-board charger for charging a high voltage battery of an electrically-charged vehicle, comprising:

a power converter configured to convert an AC voltage to a DC voltage for supplying the DC voltage to the high voltage battery to perform a charging operation, the power converter comprising a DC EMI filter; and

a controller comprising:

a DC voltage measuring device configured to measure an internal voltage of the DC EMI filter for removing noise of the DC voltage;

a leakage current estimating device configured to calculate a leakage current estimate based on the internal voltage; and

a leakage current protecting device configured to control the charging operation in accordance with the leakage current estimate,

wherein the leakage current estimating device comprises:

a low pass filter configured to remove a high-frequency noise component from the internal voltage of the DC EMI filter;

a derivative operator configured to perform a time derivative on the internal voltage to calculate a current per a unit capacitance; and

a multiplication operator configured to multiply the current per a unit capacitance by a Y-capacitor coefficient to generate the leakage current estimate.

11. The on-board charger of claim 10 , wherein the power conversion device further comprises:

an AC EMI filter configured to remove noise of the AC voltage;

a power factor correction converter configured to convert the AC voltage to the DC voltage while performing power factor correction; and

a DC/DC converter configured to change a voltage level of the DC voltage.

12. The on-board charger of claim 10 , wherein the internal voltage of the DC EMI filter is a voltage across a Y-capacitor included in the DC EMI filter.

13. The on-board charger of claim 10 , wherein the high-frequency noise component has a frequency band of about 1 kHz or more, and

wherein the Y-capacitor coefficient is a sum of capacitances of Y capacitors included in the DC EMI filter.

14. The on-board charger of claim 10 , wherein the leakage current protecting device is configured to:

temporarily stop the charging operation when the leakage current estimate is higher than a protection level;

block a current path of a DC voltage side of the on-board charger;

restart the charging operation when the leakage current estimate is equal to or lower than the protection level after a predetermined time elapses; and

terminate the charging operation when the leakage current estimate is higher than the protection level after the predetermined time elapses.

15. The on-board charger of claim 14 , wherein the leakage current protecting device is configured to transmit a charge stop request to the high voltage battery and to temporarily stop the charging operation, and

wherein the leakage current protecting device is configured to transmit a charge restart request to the high voltage battery and to restart the charging operation.

16. The on-board charger of claim 14 , wherein the leakage current protecting device is configured to:

increase a failure count while temporarily stopping the charging operation;

compare the failure count with a count upper limit after blocking the current path; and

terminate the charging operation when the failure count exceeds the count upper limit.

17. The on-board charger of claim 10 , further comprising a DC relay that connects or blocks a current path of a DC voltage side of the on-board charger.

18. An electrically-charged vehicle comprising:

the on-board charger of claim 10 ;

a high voltage battery charged with a DC voltage provided from the OBC; and

an inverter configured to drive a motor using the DC voltage discharged from the high voltage battery.