Method of controlling battery current limit values

1. A method of controlling battery current limiting that controls maximum battery charging and discharging current values according to the state of charge of the battery comprising:

integrating battery charging and discharging current to compute a first state of charge, and determining first charging and discharging current limit value candidates from that first state of charge;

computing a second state of charge based on battery voltage, and determining second charging and discharging current limit value candidates from that second state of charge; and

taking the smaller charging and discharging current limit value candidates of the first charging and discharging current limit value candidates and the second charging and discharging current limit value candidates as the charging and discharging current limit values for charging and discharging the battery,

wherein maximum charging current is reduced for a battery with a high state of charge, and maximum discharging current is reduced for a battery with a low state of charge.

2. A method of controlling battery current limiting as recited in claim 1 wherein the method of determining the second state of charge based on battery voltage determines the second state of charge based on battery voltage during charging when the state of charge is in a region greater than a set state of charge, and determines the second state of charge based on battery voltage during discharging when the state of charge is in a region less than a set state of charge.

3. A method of controlling battery current limiting as recited in claim 1 wherein the first state of charge is computed considering battery charging efficiency.

4. A method of controlling battery current limiting as recited in claim 1 wherein the second state of charge is determined based on a table of state of charge versus battery voltage.

5. A method of controlling battery current limiting as recited in claim 1 wherein the second state of charge is determined based on a function that relates state of charge to battery voltage.

6. A method of controlling battery current limiting as recited in claim 1 wherein an average value of voltage over a specified time is taken as the battery voltage to determine the second state of charge.

7. A method of controlling battery current limiting as recited in claim 2 wherein an average value of voltage over a specified time is taken as the battery voltage to determine the second state of charge.

8. A method of controlling battery current limiting as recited in claim 1 wherein the battery can be either a nickel hydrogen battery, nickel cadmium battery, or lithium ion rechargeable battery.

9. A method of controlling battery current limiting as recited in claim 1 wherein charging and discharging current limit values are limited according to the state of charge and temperature of the battery.

10. A method of controlling battery current limiting as recited in claim 8 wherein charging and discharging current limit values are determined according to state of charge and temperature using tables.

11. A method of controlling battery current limiting that controls maximum battery charging and discharging current values according to the state of charge of the battery comprising:

integrating battery charging and discharging current to compute a first state of charge, and computing a second state of charge based on battery voltage;

determining the maximum charging current value for battery charging based on the larger state of charge between the first state of charge and the second state of charge; and

determining the maximum discharging current value for battery discharge based on the smaller state of charge between the first state of charge and the second state of charge,

wherein maximum charging current is reduced for a battery with a high state of charge, and maximum discharging current is reduced for a battery with a low state of charge.

12. A method of controlling battery current limiting as recited in claim 11 wherein the method of determining the second state of charge based on battery voltage determines the second state of charge based on battery voltage during charging when the state of charge is in a region greater than a set state of charge, and determines the second state of charge based on battery voltage during discharging when the state of charge is in a region less than a set state of charge.

13. A method of controlling battery current limiting as recited in claim 11 wherein the first state of charge is computed considering battery charging efficiency.

14. A method of controlling battery current limiting as recited in claim 11 wherein the second state of charge is determined based on a table of state of charge versus battery voltage.

15. A method of controlling battery current limiting as recited in claim 11 wherein the second state of charge is determined based on a function that relates state of charge to battery voltage.

16. A method of controlling battery current limiting as recited in claim 11 wherein an average value of voltage over a specified time is taken as the battery voltage to determine the second state of charge.

17. A method of controlling battery current limiting as recited in claim 11 wherein the battery can be either a nickel hydrogen battery, nickel cadmium battery, or lithium ion rechargeable battery.

18. A method of controlling battery current limiting as recited in claim 11 wherein charging and discharging current limit values are limited according to the state of charge and temperature of the battery.

19. A method of controlling battery current limiting as recited in claim 17 wherein charging and discharging current limit values are determined according to state of charge and temperature using tables.