Method and charging device for charging a high-voltage battery of an electric vehicle

1. A method for charging a high-voltage battery of an electric vehicle, comprising:

providing the high-voltage battery having a nominal battery voltage between first and second battery terminals,

providing a charging station outputting a DC charging voltage between first and second charging terminals,

electrically connecting the first and second charging terminals and the respective first and second battery terminals without electric power being transferred from the charging station to the high-voltage battery, wherein the second charging terminal is connected to the second battery terminal via a unidirectional power transfer component interposed therebetween only allowing unidirectional power flow from the second charging terminal to the second battery terminal,

selectively pre-charging the second charging terminal to a predetermined pre-charge voltage using a controllably limited pre-charge current supplied by electric power from the high-voltage battery, and

transferring electric power from the charging station to the high-voltage battery after the predetermined pre-charge voltage has been attained at the second charging terminal of the charging station,

wherein the pre-charge current is controlled by operating a transistor in its linear operation mode.

2. The method as claimed in claim 1 , wherein the voltage at the second charging terminal is boosted by the unidirectional power transfer component to match the DC charging voltage of the charging station with the nominal battery voltage of the high-voltage battery.

3. The method as claimed in claim 1 , wherein the pre-charge voltage is predetermined to have a voltage level being the same as a voltage level handled by the high-voltage network established by the charging station and the high-voltage battery.

4. The method as claimed in claim 1 , wherein the pre-charge current is controlled by a current mirror as a function of a predetermined input current flowing between the first and second battery terminals.

5. The method as claimed in claim 1 , wherein the pre-charge current is limited to a range of about 10 mA to about 50 mA.

6. The method as claimed in claim 1 , wherein the pre-charge current is conducted through a resistance network.

7. The method as claimed in claim 1 , wherein the pre-charge current may be selectively interrupted galvanically.

8. The method as claimed in claim 1 , wherein the voltage between the first battery terminal and the second charging terminal of the charging station is monitored during charging the high-voltage battery.

9. A charging device for charging a high-voltage battery of an electric vehicle at a charging station outputting a DC charging voltage between first and second charging terminals, wherein a nominal battery voltage is provided between first and second battery terminals of the high-voltage battery, the charging device comprising:

first and second power input terminals being electrically connectable to the respective first and second charging terminals of the charging station, wherein the first power input terminal is connected to the first battery terminal, and the second power input terminal is connected to the second battery terminal,

a unidirectional power transfer component interconnected in series between the second power input terminal and the second battery terminal, the power transfer component being configured to only allow unidirectional power flow from the second power input terminal to the second battery terminal of the high-voltage battery, and

an electronic control unit configured to control a semiconductor device to selectively pre-charge the second power input terminal to a predetermined pre-charge voltage using a controllably limited pre-charge current supplied by electric power from the high-voltage battery after electrical contact has been established between the first and second power input terminals and the respective first and second charging terminals of the charging station, and before electric power is transferred from the charging station to the high-voltage battery,

wherein the semiconductor device comprises a transistor being operated in its linear operation mode to control the pre-charge current.

10. The charging device as claimed in claim 9 , wherein the unidirectional power transfer component is a DC/DC boost converter configured to boost the DC charging voltage to match with the nominal battery voltage.

11. The charging device as claimed in claim 9 , wherein the pre-charge voltage is predetermined to have a voltage level being the same as a voltage level handled by the high-voltage network established by the charging station and the high-voltage battery.

12. The charging device as claimed in claim 9 , further comprising a current mirror controlling the semiconductor device as a function of a predetermined input current flowing between the first and second battery terminals.

13. The charging device as claimed in claim 9 , wherein the pre-charge current is limited to a range of about 10 mA to about 50 mA.

14. The charging device as claimed in claim 9 , further comprising a resistance network connected in series with the semiconductor device.

15. The charging device as claimed in claim 9 , further comprising a controllable switching element configured to selectively isolate the semiconductor device from the second battery terminal galvanically.

16. The charging device as claimed in claim 15 , wherein the electronic control unit is configured to open and close the switching element.

17. The charging device as claimed in claim 9 , wherein the electronic control unit is configured to monitor the voltage between the first battery terminal and the second charging terminal of the charging station during charging the high-voltage battery.

18. An electric vehicle having a high-voltage battery, comprising a charging device for charging the high-voltage battery at a charging station outputting a DC charging voltage between first and second charging terminals, wherein a nominal battery voltage is provided between first and second battery terminals of the high-voltage battery, the charging device comprising:

first and second power input terminals being electrically connectable to the respective first and second charging terminals of the charging station, wherein the first power input terminal is connected to the first battery terminal, and the second power input terminal is connected to the second battery terminal,

a unidirectional power transfer component interconnected in series between the second power input terminal and the second battery terminal, the power transfer component being configured to only allow unidirectional power flow to the second battery terminal of the high-voltage battery, and

an electronic control unit configured to control a semiconductor device to selectively pre-charge the second power input terminal to a predetermined pre-charge voltage using a controllably limited pre-charge current supplied by electric power from the high-voltage battery after electrical contact has been established between the first and second power input terminals and the respective first and second charging terminals of the charging station, and before electric power is transferred from the charging station to the high-voltage battery

wherein the semiconductor device comprises a transistor being operated in its linear operation mode to control the pre-charge current.

19. The electric vehicle as claimed in claim 18 , wherein the high-voltage battery has a nominal battery voltage of 800 V, and wherein the unidirectional power transfer component is a DC/DC boost converter configured to boost the DC charging voltage provided by the charging station to match with the nominal battery voltage.