System for controlling output parameter of secondary battery, and method therefor

1. A system for adjusting an output parameter of a secondary battery, the system comprising:

a voltage measurement unit, a current measurement unit, and a temperature measurement unit configured to measure a voltage, a current, and a temperature of the secondary battery, respectively; and

a control unit configured to be electrically connected with the voltage measurement unit, the current measurement unit, and the temperature measurement unit,

wherein the control unit is configured to receive a measurement result from the voltage measurement unit, the current measurement unit, and the temperature measurement unit and determine a voltage, a current, and a temperature of the secondary battery during discharging of the secondary battery, to determine a state of charge of the secondary battery using the current, to determine a deration target current value calculated from a maximum value of a predefined resistance change rate, which corresponds to the state of charge and the temperature, and an output maintaining time, when the voltage of the secondary battery decreases to a preset threshold voltage or lower, and to provide an output parameter comprising at least one of the deration target current value and a deration target output value determined from the deration target current value to a control system of a load device supplied with power from the secondary battery,

wherein the output maintaining time is a time at least during which a discharging output of the secondary battery has to be maintained, and

wherein the maximum value of the predefined resistance change rate is a value obtained by dividing, by a magnitude of a maximum discharging current, a maximum of absolute values of a primary differential value calculated with respect to a discharging profile corresponding to the state of charge and the temperature of the secondary battery.

2. The system of claim 1 , wherein when a time taken until the output parameter is applied is defined as a delay time, a level of the threshold voltage is set such that when the secondary battery is discharged in a maximum discharging current value corresponding to the state of charge and the temperature, a time taken until the voltage of the secondary battery decreases to a discharging lower limit voltage from the threshold voltage is greater than the delay time and less than the output maintaining time.

3. The system of claim 1 , wherein the control unit is configured to determine a deration target current value of the secondary battery using the following equation:

I

derate

=

V

min

-

V

threshold

+

I

0

×

R

0

R

0

+

[

dR

dt

]

max

⁢

(

t

1

-

t

0

)

wherein I derate indicates a deration target current value, V min indicates a discharging lower limit voltage, V threshold indicates a threshold voltage, I 0 indicates a discharging current value when the voltage of the secondary battery reaches the threshold voltage or a maximum discharging current value corresponding to the state of charge and the temperature of the secondary battery, R 0 indicates an internal resistance of the secondary battery, t 1 −t 0 indicates the output maintaining time, (dR/dt) max indicates the maximum value of the predefined resistance charge rate which is obtained by dividing, by the magnitude of the maximum discharging current, I max , the maximum of absolute values of a primary differential value dV/dt calculated with respect to the discharging profile corresponding to the state of charge and the temperature of the secondary battery between two intersections at which the discharging profile meets a straight line V=V threshold and a straight line V=V min , and I max indicates the maximum discharging current value corresponding to the state of charge and the temperature of the secondary battery.

4. The system of claim 1 , wherein the control unit is configured to determine a deration target output value based on multiplication of the deration target current value and a discharging lower limit voltage.

5. The system of claim 1 , further comprising a memory unit configured to store a maximum value of a predefined resistance change rate corresponding to the state of charge and the temperature.

6. The system of claim 1 , further comprising a communication interface electrically coupled with the control unit,

wherein the control unit is configured to periodically transmit the output parameter to the control system through the communication interface.

7. The system of claim 1 , wherein the control unit is configured to determine a maximum discharging current value corresponding to a state of charge and a temperature of the secondary battery by referring to data of a maximum discharging current value that is predefined for each state of charge and each temperature of the secondary battery when a voltage of the secondary battery is higher than the threshold voltage, and

to provide an output parameter comprising at least one of the maximum discharging current value and an available output value calculated from the maximum discharging current value to a control system of the load device.

8. A method of adjusting an output parameter of a secondary battery, the method comprising:

(a) measuring a voltage, a current, and a temperature of the secondary battery during discharging of the secondary battery;

(b) determining a state of charge of the secondary battery by using the current;

(c) determining a deration target current value from a maximum value of a predefined resistance change rate, which corresponds to the state of charge and the temperature, and an output maintaining time, when the voltage of the secondary battery decreases to a preset threshold voltage or lower;

(d) determining an output parameter comprising at least one of the deration target current value and the deration target output value determined from the deration target current value; and

(e) providing the output parameter to a control system of a load device supplied with power from the secondary battery,

wherein the output maintaining time is a time at least during which a discharging output of the secondary battery has to be maintained, and

wherein the maximum value of the predefined resistance change rate is a value obtained by dividing, by a magnitude of a maximum discharging current, a maximum of absolute values of a primary differential value calculated with respect to a discharging profile corresponding to the state of charge and the temperature of the secondary battery.

9. The method of claim 8 , wherein when a time taken until the output parameter is applied is defined as a delay time, a level of the threshold voltage is set such that when the secondary battery is discharged by a maximum discharging current value corresponding to the state of charge and the temperature, a time taken until a voltage of the secondary battery decreases to a discharging lower limit voltage from the threshold voltage is greater than the delay time and less than the output maintaining time.

10. The method of claim 8 , wherein the operation (c) comprises determining a deration target current value of the secondary battery using the following equation:

I

derate

=

V

min

-

V

threshold

+

I

0

×

R

0

R

0

+

[

dR

dt

]

max

⁢

(

t

1

-

t

0

)

wherein I derate indicates a deration target current value, V min indicates a discharging lower limit voltage, V threshold indicates a threshold voltage, I 0 indicates a discharging current value when the voltage of the secondary battery reaches the threshold voltage or a maximum discharging current value corresponding to the state of charge and the temperature of the secondary battery, R 0 indicates an internal resistance of the secondary battery, t 1 −t 0 indicates the output maintaining time, (dR/dt) max indicates the maximum value of the predefined resistance charge rate which is obtained by dividing, by the magnitude of a maximum discharging current, I max , the maximum of absolute values of a primary differential value dV/dt calculated with respect to the discharging profile corresponding to the state of charge and the temperature of the secondary battery between two intersections at which the discharging profile meets a straight line V=V threshold and a straight line V=V min , and I max indicates the maximum discharging current value corresponding to the state of charge and the temperature of the secondary battery.

11. The method of claim 8 , wherein the operation (d) comprises determining a deration target output value based on multiplication of the deration target current value and a discharging lower limit voltage.

12. The method of claim 8 , wherein the operation (e) comprises periodically transmitting the output parameter to the control system through a communication interface.

13. The method of claim 8 , further comprising:

determining the maximum discharging current value corresponding to the state of charge and the temperature of the secondary battery by referring to data of the maximum discharging current value that is predefined for each state of charge and each temperature of the secondary battery when a voltage of the secondary battery is higher than the threshold voltage;

determining an output parameter comprising at least one of the maximum discharging target current value and an available output value calculated from the maximum discharging target current value; and

providing the output parameter to the control system of the load device.

14. A system for adjusting an output parameter of a secondary battery, the system comprising:

a voltage measurement unit, a current measurement unit, and a temperature measurement unit configured to measure a voltage, a current, and a temperature of the secondary battery, respectively; and

a control unit configured to be electrically connected with the voltage measurement unit, the current measurement unit, and the temperature measurement unit,

wherein the control unit is configured to receive a measurement result from the voltage measurement unit, the current measurement unit, and the temperature measurement unit and determine a voltage, a current, and a temperature of the secondary battery during charging of the secondary battery, to determine a state of charge of the secondary battery using the current, to determine a deration target current value calculated from a maximum value of a predefined resistance change rate, which corresponds to the state of charge and the temperature, and an output maintaining time, when the voltage of the secondary battery increases to a preset threshold voltage or higher, and to provide an output parameter comprising at least one of the deration target current value and a deration target output value determined from the deration target current value to a control system of a load device supplied with power from the secondary battery,

wherein the output maintaining time is a time at least during which a discharging output of the secondary battery has to be maintained, and

wherein the maximum value of the predefined resistance change rate is a value obtained by dividing, by the magnitude of a maximum discharging current, a maximum of absolute values of a primary differential value calculated with respect to a discharging profile corresponding to the state of charge and the temperature of the secondary battery.

15. A method of adjusting an output parameter of a secondary battery, the method comprising:

(a) measuring a voltage, a current, and a temperature of the secondary battery during charging of the secondary battery;

(b) determining the state of charge of the secondary battery by using the current;

(c) determining a deration target current value from a maximum value of a predefined resistance change rate, which corresponds to the state of charge and the temperature, and an output maintaining time, when the voltage of the secondary battery increases to a preset threshold voltage or higher;

(d) determining an output parameter comprising at least one of the deration target current value and the deration target output value determined from the deration target current value; and

(e) providing the output parameter to a control system of a load device supplying charging power to the secondary battery,

wherein the output maintaining time is a time at least during which a discharging output of the secondary battery has to be maintained, and

wherein the maximum value of a predefined resistance change rate is a value obtained by dividing, by a magnitude of a maximum discharging current, a maximum of absolute values of a primary differential value calculated with respect to a discharging profile corresponding to the state of charge and the temperature of the secondary battery.