KR100384160B1 - Method for modeling operation the charge/discharge characteristics of a battery according to a status of capacitance - Google Patents

Abstract

The present invention relates to a charging / discharging characteristic modeling method for each battery remaining capacity. In this method, the battery charging equivalent voltage is defined according to the following equation using the charging internal resistance and the charging no-load voltage, the charging internal resistance and the charging no-load voltage are calculated according to the remaining capacity, and the charging voltage for each remaining capacity is calculated. The discharge equivalent voltage is defined according to the following equation using the discharge internal resistance and the discharge no-load voltage, and the discharge voltage for each remaining capacity is calculated by calculating the discharge internal resistance and the discharge no-load voltage according to the remaining capacity. The remaining capacity is characterized by the capacitor component of the battery. According to the present invention, it is possible to easily predict the current-voltage relationship for each remaining capacity of the battery system to enhance the battery control function, facilitate the execution of the battery simulation before the battery test can be shortened the test period and development period.

Description

METHODS FOR MODELING OPERATION THE CHARGE / DISCHARGE CHARACTERISTICS OF A BATTERY ACCORDING TO A STATUS OF CAPACITANCE}

The present invention relates to a charging / discharging characteristic modeling method for each battery remaining capacity. More specifically, the battery characteristics are identified only by the variation of the battery no-load voltage and the charging / discharging internal resistance excluding the effect of the capacitor, and the effect of the capacitor is determined by the control logic. The present invention relates to a charging / discharging characteristic modeling method for each battery remaining capacity that predicts battery remaining capacity.

In general, a method of modeling a battery characteristic as an electric circuit is a method using a THEVENIN equivalent circuit. The equivalent circuit is shown in FIG. 1, and the charge / discharge equivalent voltage is as follows.

Charge equivalent voltage:

Discharge equivalent voltage:

Where V _oc is the no-load voltage, R _dch is the discharge internal resistance, R _cha is the charge internal resistance, C _dch is the discharge capacitance, and C _cha is the charge capacitance.

As can be seen from the above equation, the modeling method using a general Thevenin equivalent circuit uses the battery no-load voltage, the charge / discharge internal resistance, and the capacitance to express the battery characteristics as a function of electrical time. The dynamic characteristics of were observed.

However, it is not easy to model the battery no-load voltage, the charge / discharge internal resistance, and the component values of the capacitor, which change according to the remaining capacity of the battery, and in the case of a hybrid electric vehicle in which charge / discharge is repeated, the capacitance varies according to the driving conditions of the vehicle. There is a problem that modeling battery dynamic characteristics is not easy because the value is not easy to measure.

Accordingly, an object of the present invention is to solve the above-mentioned conventional problems, and to determine battery characteristics by only changing the battery no-load voltage and charge / discharge internal resistance except the effect of the capacitor, and the effect of the capacitor in consideration of the control logic of the battery The present invention provides a charging / discharging characteristic modeling method for each battery remaining capacity that predicts remaining capacity.

1 is a Thevenin equivalent circuit diagram for general battery characteristics.

2 is a Thevenin equivalent circuit diagram for battery characteristics according to an exemplary embodiment of the present invention, FIG. 2A is a charge equivalent circuit diagram, and FIG. 2B is a discharge equivalent circuit diagram.

3 is a diagram illustrating the Thevenin charge / discharge internal resistance for each battery remaining capacity according to an embodiment of the present invention.

4 is a diagram illustrating a charge / discharge no-load voltage for each battery remaining capacity according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a charge / discharge voltage for each remaining capacity according to an embodiment of the present invention. FIG. 5A is a diagram illustrating a charge voltage, and FIG. 5B is a diagram illustrating a discharge voltage.

As a means for achieving the above object, the present invention defines a battery charge equivalent voltage according to the following equation using the charge internal resistance and the charge no-load voltage, and obtain the remaining charge internal resistance and charge no-load voltage according to the remaining capacity The charging voltage for each capacity is calculated, and the battery discharge equivalent voltage is defined according to the following equation using the discharge internal resistance and the discharge no-load voltage, and the discharge internal resistance and the discharge no-load voltage according to the remaining capacity are obtained to obtain the discharge voltage for each remaining capacity. It is characterized in that for calculating the remaining capacity (SOC) is characterized in that determined by the capacitor component of the battery.

The charging internal resistance is calculated by the difference between the charging current for the first constant current and the charging current for the second constant current, and the difference between the charging voltage for the first constant current and the charging voltage for the second constant current. And the discharge internal resistance is a difference between the discharge current for the first constant current and the discharge current for the specified third constant current, and the difference between the discharge voltage for the first constant current and the discharge voltage for the third constant current. Calculated by

The charging no-load voltage is calculated using the charging current for the first constant current, the charging voltage for the first constant current, and the charging internal resistance, and the discharge no-load voltage is the discharge current for the first constant current, the first voltage. It calculates using the discharge voltage with respect to 1 constant current, and the said discharge internal resistance.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a Thevenin equivalent circuit diagram for battery characteristics according to an exemplary embodiment of the present invention, FIG. 2A is a charge equivalent circuit diagram, and FIG. 2B is a discharge equivalent circuit diagram.

As shown in FIG. 2, in the charging / discharging characteristic modeling of each battery remaining capacity according to the exemplary embodiment of the present invention, the effect of the capacitor, that is, the capacitance is omitted.

The charge / discharge equivalent voltage for such an equivalent circuit is as follows.

Charge equivalent voltage:

Discharge equivalent voltage:

As can be seen from the above equation, the capacitance, which is the effect of the capacitor, is missing.

On the other hand, the internal resistance of the battery can be largely divided into electrical resistance by the positive / negative terminal and the current collector and electrochemical resistance by the chemical reaction according to the state of charge.

In this embodiment, the value of the electrical resistance and the electrochemical resistance according to the state of charge is set to the battery charge / discharge internal resistance value for each remaining capacity based on the charge / discharge test data.

After charging the constant current (1C, 2C), the data is converted to the remaining capacity axis, and then the battery Thevenin internal resistance is calculated using the following equation.

Charge Internal Resistance:

Discharge internal resistance:

Where CHA_Volt_2C and CHA_Volt_2C are the charging voltages of the constant currents (2C, 1C), CHA_A_2C and CHA_A_1C are the charging currents of the constant currents (2C, 1C), respectively, SOC is the remaining capacity of the battery, and DCH_Volt_1C and DCH_Volt_0.3C, respectively It is a discharge voltage of (1C, 0.3C), and DCH_A_1C and DCH_A_0.3C are discharge currents of constant currents 1C and 0.3C, respectively.

At this time, the charge internal resistance for each remaining capacity is calculated by the difference in charge voltage and current between the constant currents (2C, 1C), and the discharge internal resistance for each remaining capacity is the discharge voltage difference and current between the constant currents (1C, 0.3C). Calculated by the car

The thevenin charge / discharge internal resistance for each battery remaining capacity calculated by the above equation is shown in FIG. 3.

On the other hand, the no-load voltage for each remaining capacity is calculated by the following equation using the above-mentioned Thevenin internal resistance value for each remaining battery capacity and the charge / discharge voltage and current of the constant current (1C).

Charge no load voltage:

Discharge No Load Voltage:

As such, the charge no-load voltage for each remaining capacity is calculated by the charge voltage, the charge current, and the charge internal resistance of the constant current (1C), and the discharge no-load voltage for the remaining capacity is the discharge voltage, the discharge current, and the discharge of the constant current (1C). It is calculated by internal resistance.

The charge / discharge no-load voltage for each battery remaining capacity calculated by the above equation is shown in FIG. 4.

As described above, the battery characteristic Thevenin charge / discharge voltage may be calculated only by the internal resistance and the no-load voltage.

The current remaining capacity is then determined using the relationship between battery current versus voltage and battery control variables (current, voltage, temperature, etc.).

First, an initial characteristic of the battery charge / discharge voltage according to the remaining capacity for any charge / discharge current is calculated by the following equation, which is the basis of the battery control logic.

charge : --- (One)

Discharge : --- (2)

The initial charge / discharge characteristics of the battery according to the remaining capacity calculated by the above equation are shown in FIGS. 5A and 5B.

Next, the temperature compensation for the battery charge / discharge voltage for each remaining capacity is calculated by the following equation.

Charge / discharge: IV "_" Volt = Temp_Compensation_f (Battery "_" Temp, V_b (t)) @ 28 ℃ --- (3)

Thereafter, a value close to the calculated charging / discharging initial characteristic is found as the primary residual capacity by the temperature-compensated voltage in the above equation, and the residual capacity suitable for the state of the battery is obtained by multiplying the aging coefficient as follows.

charge : - (4)

Discharge : _ (5)

Here, Aging_Factor is an aging coefficient.

The aging coefficient is an available ratio of initial capacity, which is an important variable in calculating the cumulative remaining capacity and the current remaining capacity. As the battery charge / discharge cycle progresses, the available capacity gradually decreases, thereby increasing the aging coefficient.

After the primary residual capacity is calculated while driving, the aging coefficient is calculated by using the actual amount of charged / discharged Ah until the secondary residual capacity is calculated as a variable as follows.

Here, IVSOC (t1) and IVSOC (t2) are primary remaining capacity and secondary remaining capacity, respectively, Init_Base_Ah and Accumulated_Ah represent initial Ah capacity and cumulative Ah capacity, and Batt_Temp_Efficiency represents battery temperature efficiency.

On the other hand, the Ah remaining capacity is calculated by adding or subtracting from the previous remaining capacity by converting the average charge / discharge average current amount of unit time into a percentage after considering capacity efficiency, battery temperature efficiency, and battery aging as follows.

here,

to be.

In addition, the battery voltage corresponding to the current remaining capacity is calculated using the battery current vs. voltage relationship for each remaining capacity as shown in the following equation, and then the input battery voltage is higher or lower than the calculated value several times or more. In this case, it is determined that the current remaining capacity is out of the error range.

charge :

Discharge :

In addition, the current remaining capacity is calculated using the battery current versus voltage relationship during constant current charging, and the Ah remaining capacity is corrected according to Equations (1) to (5) above when the increase slope of the value is constant for several times. .

In addition, after the voltage corresponding to the difference of ± 5% of the remaining capacity of the maximum and minimum modules of the battery pack is obtained by the following equation, the battery equalization is performed to the user when the occurrence of the voltage exceeding the voltage several times persists. Requires.

charge :

Discharge :

In addition, the charge / discharge power after the battery temperature compensation is calculated using the battery maximum charge / discharge power min current relationship at the current remaining capacity as follows.

charge :

Discharge :

In addition, compensation for battery cooling control, battery safety check, etc. may be further implemented.

Although the present invention has been described with reference to the most practical and preferred embodiments, the present invention is not limited to the above disclosed embodiments, but also includes various modifications and equivalents within the scope of the following claims.

According to the present invention, it is possible to easily predict the current-voltage relationship for each remaining capacity of the battery system to enhance the battery control function, facilitate the execution of the battery simulation before the battery test can be shortened the test period and development period.

Claims (3)

In the method for modeling the charge and discharge characteristics for each battery remaining capacity, The following equation is used to charge the battery charging equivalent voltage using the internal resistance and no-charge voltage. V_cha = V_ocha + A_cha × R_cha Where V_cha is the charge voltage, V_ocha is the charging no-load voltage, A_cha is the charging current, and R_cha is the charge internal resistance And charge voltage for each remaining capacity by calculating the charge internal resistance and the charge no-load voltage according to the remaining capacity. Battery discharge equivalent voltage using discharge internal resistance and discharge no load voltage V_dch = V_odch + A_dch × R_dch Where V_dch is the discharge voltage, V_odch is the discharge no-load voltage, A_dch is the discharge current, and R_dch is discharge internal resistance And the discharge internal resistance and the discharge no-load voltage according to the remaining capacity, and calculate the discharge voltage for each remaining capacity. The remaining capacity SOC is determined by the capacitor component of the battery Method of modeling charging and discharging characteristics by battery remaining capacity. The method of claim 1, The charging internal resistance R_cha is a difference between the charging current A_cha_1C for the specified first constant current and the charging current A_cha_2C for the second constant current, the charging voltage V_cha_1C for the first constant current, and the first voltage. The relation below is given by the difference between the charging voltage (V_cha_2C) for the constant current. R_cha = Is calculated according to The discharge internal resistance R_dch is a difference between the discharge current A_dch_1C for the first constant current and the discharge current A_dch_3C for the specified third constant current, the discharge voltage V_dch_1C for the first constant current, and the The following relation is obtained by the difference between the discharge voltage V_dch_3C and the third constant current. R_dch = Calculated according to Method of modeling charging and discharging characteristics by battery remaining capacity. The method of claim 1, The charging no-load voltage V_ocha is represented by the following relation using the charging current A_cha_1C for the first constant current, the charging voltage V_cha_1C for the first constant current, and the charging internal resistance R_cha. Is calculated according to The discharge no-load voltage V_odch is represented by the following relation using the discharge current A_dch_1C for the first constant current, the discharge voltage V_dch_1C for the first constant current, and the discharge internal resistance R_dch. Calculated according to How to model battery charge and discharge characteristics.