System and method for parallel battery pack charging
A battery management system is provided with a first charging circuit including a first switch to connect a first battery pack to a power source. A second charging circuit includes a second switch to connect a second battery pack to the power source, wherein the second charging circuit is arranged in parallel with the first charging circuit. A discharge circuit includes a discharge switch to connect the first battery pack and the second battery pack in series. A processor is programmed to: open the discharge switch; receive input indicative of a first battery voltage and a second battery voltage; close the first switch and open the second switch in response to the first battery voltage being less than the second battery voltage; and close the first switch and close the second switch in response to the first battery voltage being approximately equal to the second battery voltage.
1. A battery management system, comprising:
a first battery pack;
a second battery pack;
a first charging circuit with a first switch to connect the first battery pack to a power source to enable charging;
a second charging circuit with a second switch to connect the second battery pack to the power source to enable charging, wherein the second charging circuit is arranged in parallel with the first charging circuit; and
a processor programmed to:
receive an input indicative of a first battery voltage and of a second battery voltage;
close the first switch and open the second switch, to enable charging of the first battery pack at a first charging current and disable charging of the second battery pack, in response to the first battery voltage being less than the second battery voltage;
reduce the first charging current to a second charging current in response to a difference between the first battery voltage and the second battery voltage being less than a predetermined threshold value and the first charging current exceeding a charging current threshold value; and
close the first switch and the second switch, to enable charging of the first battery pack and the second battery pack in parallel, in response to the first battery voltage being approximately equal to the second battery voltage.
2. The battery management system of claim 1 , wherein the first battery pack and the second battery pack are each adapted to provide DC power at a maximum voltage of approximately 400 Volts.
3. The battery management system of claim 1 further comprising a discharge circuit with a discharge switch to connect the first battery pack and the second battery pack in series to collectively provide DC power at a maximum voltage of approximately 800 Volts.
4. The battery management system of claim 1 further comprising a pre-charging switch and a resistor connected in series, wherein the pre-charging switch, together with the resistor are connected in parallel with the first switch, wherein the processor is further programmed to:
close the pre-charging switch and open the first switch to enable pre-charging of the first battery pack; and
in response to a pre-charging voltage exceeding a pre-charging voltage threshold value, open the pre-charging switch and close the first switch to enable charging of the first battery pack.
5. The battery management system of claim 1 , wherein the second charging current is approximately equal to one half of the first charging current.
6. The battery management system of claim 1 , wherein the processor is further programmed to reduce the second charging current to a third charging current in response to a difference between the first battery voltage and the second battery voltage being less than the predetermined threshold value, wherein the third charging current is approximately equal to one half of the second charging current.
7. The battery management system of claim 1 , wherein the processor is further programmed to close the second switch and open the first switch to enable charging of the second battery pack at a second battery pack charging current in response to input indicative of the second battery voltage being less than the first battery voltage.
8. The battery management system of claim 7 further comprising a pre-charging switch and a resistor connected in series, wherein the pre-charging switch, together with the resistor, are connected in parallel with the second switch, wherein the processor is further programmed to:
close the pre-charging switch and open the second switch to enable pre-charging of the second battery pack; and
in response to a pre-charging voltage exceeding a pre-charging voltage threshold value, open the pre-charging switch and close the second switch to enable charging of the second battery pack.
9. The battery management system of claim 7 , wherein the processor is further programmed to reduce the second battery pack charging current in response to a difference between the second battery voltage and the first battery voltage being less than a predetermined threshold value.
10. A battery management system, comprising:
a first charging circuit with a first switch to connect a first battery pack to a power source;
a second charging circuit with a second switch to connect a second battery pack to the power source, wherein the second charging circuit is arranged in parallel with the first charging circuit;
a discharge circuit with a discharge switch to connect and disconnect the first battery pack and the second battery pack in series; and
a processor programmed to:
open the discharge switch;
receive input indicative of a first battery voltage and a second battery voltage;
close the first switch and open the second switch, to enable charging of the first battery pack at a first charging current, in response to the first battery voltage being less than the second battery voltage;
reduce the first charging current to a second charging current in response to a difference between the first battery voltage and the second battery voltage being less than a predetermined threshold value and the first charging current exceeding a charging current threshold value; and
close the first switch and close the second switch, to enable charging of the first battery pack and the second battery pack in parallel, in response to the first battery voltage being approximately equal to the second battery voltage.
11. The battery management system of claim 10 further comprising a pre-charging switch and a resistor connected in series, wherein the pre-charging switch, together with the resistor, are connected in parallel with the first switch, wherein the processor is further programmed to:
close the pre-charging switch and open the first switch to enable pre-charging of the first battery pack; and
in response to a pre-charging voltage exceeding a pre-charging voltage threshold value, open the pre-charging switch and close the first switch to enable charging of the first battery pack.
12. A method for charging a battery assembly, comprising:
opening a discharge switch connected between a first battery pack and a second battery pack;
receiving input indicative of a first battery voltage and a second battery voltage;
closing a first switch to connect the first battery pack to a power source to enable charging of the first battery pack at a first charging current in response to the first battery voltage being less than the second battery voltage;
reducing the first charging current to a second charging current in response to a difference between the first battery voltage and the second battery voltage being less than a predetermined threshold value and the first charging current exceeding a charging current threshold value; and
closing the first switch and closing a second switch to connect the second battery pack to the power source, to enable charging of the first battery pack and the second battery pack in parallel, in response to the first battery voltage being approximately equal to the second battery voltage.
13. The method of claim 12 further comprising:
providing a pre-charging switch and a resistor connected in series, wherein the pre-charging switch, together with the resistor, are connected in parallel with the first switch;
closing the pre-charging switch and opening the first switch to enable pre-charging of the first battery pack; and
in response to a pre-charging voltage exceeding a pre-charging voltage threshold value, opening the pre-charging switch and closing the first switch to enable charging of the first battery pack.
14. The method of claim 12 further comprising closing the second switch and opening the first switch to enable charging of the second battery pack at a third charging current in response to input indicative of the second battery voltage being less than the first battery voltage.
15. The method of claim 14 further comprising reducing the third charging current to a fourth charging current in response to a difference between the second battery voltage and the first battery voltage being less than a predetermined threshold value.
16. The method of claim 12 further comprising:
providing a pre-charging switch and a resistor connected in series, wherein the pre-charging switch, together with the resistor, are connected in parallel with the second switch;
closing the pre-charging switch and opening the second switch to enable pre-charging of the second battery pack; and
in response to a pre-charging voltage exceeding a pre-charging voltage threshold value, opening the pre-charging switch and closing the second switch to enable charging of the second battery pack.