KR101065591B1 - battery management system for estimating battery state of charge and method thereof - Google Patents

Abstract

Disclosed are a battery management system and method for estimating a state of charge of a battery according to the present invention. The battery management system according to the present invention includes a controller configured to determine a first estimation mode or a second estimation mode for estimating a state of charge (SOC) of a battery; An SOC estimator configured to estimate an SOC of the battery based on the voltage, current, and temperature of the battery measured according to the determined first estimation mode or the second estimation mode; And an SOC correction unit for correcting the SOC of the battery estimated according to internal and external factors of the battery. Through this, the present invention can effectively estimate the state of charge of the battery, it is possible to accurately estimate the state of charge of the battery.

Battery Management System, Batteries, Charge Status, SOC, Charge, Discharge, Boltzman, Peukert

Description

Battery management system for estimating battery charge state and method thereof

The present invention relates to a battery management system and method for estimating battery state of charge.

Recently, since automobiles using internal combustion engines using gasoline or heavy oil as main fuels have a serious effect on pollution generation such as air pollution, many studies have been conducted to reduce such pollution occurrences. Much effort is being made in the development of automobiles or hybrid vehicles.

An electric vehicle is a vehicle using a battery engine operated by electric energy output from a battery, and a plurality of secondary cells that can be charged and discharged are formed in one pack, thereby charging or discharging performance. It uses this high-capacity battery as the main power source, so there is no exhaust and no noise.

Since the performance of a battery directly affects the performance of a vehicle, an electric vehicle using electric energy not only needs to have excellent performance of each battery cell but also measures the voltage of each battery cell, the voltage and current of the entire battery, and the like. There is an urgent need for a battery management system that can efficiently manage charging and discharging.

The battery management system estimates the state of charge of the battery by detecting the discharge current, temperature, and voltage of the battery from the discharge start time, and does not consider the characteristics of the battery at the charge and discharge time. The estimate is inaccurate.

The present invention is to solve the above problems of the prior art, by estimating the state of charge of the battery in different ways according to the charging or discharging mode, to estimate the state of charge of the battery to effectively estimate the state of charge of the battery To provide a battery management system and a method thereof.

In addition, the present invention provides a battery management system and method for estimating the state of charge of a battery to enable accurate estimation of the state of charge of the battery by correcting the state of charge of the battery estimated according to the state of charge or discharge according to internal and external factors. To provide.

To this end, the battery management system for estimating the state of charge of a battery according to an aspect of the present invention includes a control unit for determining a first estimation mode or a second estimation mode for estimating the state of charge (SOC) of the battery; An SOC estimator configured to estimate an SOC of the battery based on the voltage, current, and temperature of the battery measured according to the determined first estimation mode or the second estimation mode; And an SOC correction unit for correcting the SOC of the battery estimated according to internal and external factors of the battery.

In this case, the first estimation mode may be an initial state in which charging and discharging of the battery are not performed, or a charging state of the battery, and the second estimation mode may be a discharge state of the battery.

Preferably, the SOC estimator may estimate the SOC of the battery using a Boltzman equation based on the voltage, current, and temperature of the battery according to the first estimation mode, and the SOC corrector may be configured to determine an internal and external factors of the battery. Accordingly, the SOC of the battery estimated based on the compensated parameters may be corrected by compensating at least one parameter of the Boltzman equation.

Preferably, the SOC estimator may estimate the SOC of the battery using a Peukert equation based on the voltage, current, and temperature of the battery according to the second estimation mode, and the SOC corrector may be configured to determine an internal and external factors of the battery. Accordingly, the SOC of the battery estimated based on the compensated parameters may be corrected by compensating at least one parameter of the Peukert equation.

At this time, the internal and external factors of the battery may be at least one of the internal temperature of the battery during charging and discharging, the number of charging and discharging, aging, charging and discharging current.

A method for estimating a state of charge of a battery according to an aspect of the present invention includes determining a first estimation mode or a second estimation mode for estimating a state of charge (SOC) of a battery; Estimating the SOC of the battery based on the voltage, current, and temperature of the battery measured according to the determined first estimation mode or the second estimation mode; And correcting the SOC of the battery estimated according to internal and external factors of the battery.

In this case, the first estimation mode may be an initial state in which charging and discharging of the battery are not performed, or a charging state of the battery, and the second estimation mode may be a discharge state of the battery.

Preferably, estimating the SOC of the battery may estimate the SOC of the battery using a Boltzman equation based on the voltage, current, and temperature of the battery according to the first estimation mode, and calculates the SOC of the battery. The correcting step may correct the estimated SOC of the battery based on the compensated parameter by compensating at least one parameter of the Boltzman equation according to internal and external factors of the battery.

Preferably, estimating the SOC of the battery may estimate the SOC of the battery using a Peukert equation based on the voltage, current, and temperature of the battery according to the second estimation mode, and calculates the SOC of the battery. The correcting step may correct the estimated SOC of the battery based on the compensated parameter by compensating at least one parameter of the Peukert equation according to internal and external factors of the battery.

At this time, the internal and external factors of the battery may be at least one of the internal temperature of the battery during charging and discharging, the number of charging and discharging, aging, charging and discharging current.

Hereinafter, a battery management system and method for estimating a state of charge of a battery according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6. The present invention estimates the state of charge of the battery in different ways according to the charging or discharging mode, and determines the state of charge of the battery estimated according to the charging or discharging state according to at least one characteristic information, for example, temperature, number of charge / discharge cycles, aging, and the like. It is to be corrected.

1 is an exemplary view showing the configuration of a schematic system according to an embodiment of the present invention.

As shown in FIG. 1, a battery management system according to an embodiment of the present invention includes a voltage detector 110, a current detector 120, a temperature detector 130, and a controller 140. , SOC estimator 150, SOC compensator 160, memory 170, and the like.

The voltage detector 110 may detect the voltage of the battery, the current detector 120 may detect the current of the battery, and the temperature detector 130 may detect the temperature of the battery. The detected voltage, charge and discharge current, and temperature of the battery may be used to estimate the state of charge (SOC) of the battery during operation or charging.

The controller 140 may determine a method of estimating the SOC of the battery, that is, the first estimation mode and the second estimation mode. According to the determination result, the SOC estimator 150 estimates the SOC of the battery using the Boltzman equation in the first estimation mode, and the SOC estimator 150 uses the Peukert equation in the second estimation mode. SOC can be estimated.

Here, the first estimation mode may mean a case where the battery is in an initial state or a charging state in which charging or discharging is not performed, and the second estimation mode may mean a case where the battery is in a discharge state.

The SOC correction unit 160 may correct the SOC of the battery estimated according to the first estimation mode and the second estimation mode, respectively. Factors affecting the charge / discharge characteristics of the battery, such as temperature, the number of charge / discharge cycles, and aging, etc. In consideration of this, the estimated SOC of the battery can be corrected.

In addition, the memory 170 may be used to store or update values of parameters of the Boltzman equation and the Peukert equation required for estimating the SOC of the battery.

2 is an exemplary view showing a method for estimating a state of charge of a battery according to an embodiment of the present invention.

As shown in FIG. 2, the battery management system may determine whether the battery is in an initial state, a charged state or a discharged state (S201). May be determined as the first estimation mode.

According to the first estimation mode, the battery management system may estimate the SOC of the battery by detecting the voltage of the battery and using the Boltzman equation of Equation 1 below (S211).

[Equation 1]

Here, A1 represents the voltage at SOC 0%, A2 represents the voltage at SOC 100%, V ₀ represents the voltage at SOC 50%, and d _V may represent the slope of the graph.

3 is a first exemplary view showing a boltzman graph according to an embodiment of the present invention.

As shown in FIG. 3, the SOC is shown according to the sensed voltage of the battery. That is, the lower the voltage of the battery, the lower the SOC, and the higher the voltage of the battery, the higher the SOC. This can be seen that the SOC is also constant.

In this case, the charging mode may be divided into a constant power mode (CP), a first constant current step (Constant Current step 1 mode), a second constant current step (Constant Current step 2 mode), stabilization mode, each charge Depending on the mode, the parameters A1, A2, V ₀ and d _V of Boltzman equation can be applied differently.

In particular, among the parameters A1, A2, V ₀ , d _V of Boltzman's equation, A1 may represent the discharge end voltage of the battery, and parameter A2 may represent the charge end voltage. This can be determined through the characteristic graph.

In addition, the Boltzman equation parameters A1, A2, V _{0, V} d of V _{0, V} d can be determined by the charging curve of the battery, it will be described with reference to FIG. 4 to FIG.

4 is a second exemplary view showing a boltzman graph according to an embodiment of the present invention.

4, can be seen that the graph is changed according to the change of d _V in the parameters A1, A2, V _0, d _V of the V ₀ of the Boltzman equation fixed state, that is, V ₀ is In the fixed state, the slope of the graph becomes smoother as d _V increases, and the slope of the graph rapidly increases as d _V decreases.

5 is a third exemplary view showing a boltzman graph according to an embodiment of the present invention.

As shown in Figure 5, can be seen that of the parameters A1, A2, V _0, d _V of Boltzman equation d _V a is the trend graph in accordance with the change of V ₀ at a fixed state, that is, d _V is You can see the graph move to the right as V ₀ increases and decreases in the fixed state.

The battery management system can then correct the estimated SOC of the battery, since the charge and discharge curve or usable capacity of the battery may vary depending on external and internal factors. For example, the internal factors may include the internal temperature of the battery during charge and discharge, the number of charge / discharge cycles, aging, and the like, and the external factors may include charge / discharge current, external temperature, and the like.

In this case, a method of correcting the SOC of the battery according to the temperature will be described as an example.

The correction method by temperature varies depending on the type of battery. In the case of lead-acid batteries, the internal resistance component tends to increase as the temperature increases. In the case of Ni-MH, the internal resistance component tends to decrease as the temperature increases. . That is, in the charge / discharge characteristic curve, the end-of-charge voltage and the end-of-discharge voltage vary depending on the temperature, and the degree of inclination or the center point may move.

In order to apply this to Equation 1, the parameter A1 is compensated when the discharge end voltage is changed, A2 is compensated when the charge end voltage is changed, and d _V is compensated when the slope is changed, and the center point moves. If by compensating for V ₀ (S212), based on the compensation parameters A1, A2, _V d, V ₀ can correct the SOC of the battery (S213).

On the other hand, the battery management system may determine that the discharge state is the second estimation mode as a result of the determination.

According to the second estimation mode, the battery management system may estimate the SOC of the battery by detecting the voltage of the battery and using the Peukert equation of Equation 2 below (S221).

[Equation 2]

Here, SOC _initial may represent an _initial discharge value, Ah_used may represent a usable capacity to date, and Ah_available may represent a usable capacity of a battery.

In this case, Ah_available may be expressed as Equation 3 below.

&Quot; (3) "

Here, Iavg may represent an average current of the battery, and K and n may represent constants.

In this case, K and n can be expressed as Equation 4 below.

&Quot; (4) "

Here, I ₁ represents the maximum current of the battery during operation, I ₂ represents the minimum current of the battery during operation, t ₁ represents the discharge time of I ₁ , t ₂ may represent the discharge time of I ₂ , respectively. . An example of setting constants K and n will be described with reference to FIG. 6.

6 is an exemplary view showing a peukert graph according to an embodiment of the present invention.

As shown in FIG. 6, the rated capacity of the battery is 90AHr, and the usable capacity thereof may vary depending on the discharge current, and it can be seen that the discharge current capacity is divided into three stages.

Step 1)

I _b = 2 A (0.022 C, Imin) to 30 A (C / 3, I _max )

I _min (I ₂ ): 92Ah, 46 h (t ₂ )

I _max (I ₁ ): 87Ah, 2.9 h (t ₁ )

Thus K ₁ = 93.25, n ₁ = 1.02041

Step 2)

I _b = 30 A (C / 3, I _min ) to 90 A (1C, I _max )

I _min (I ₂ ): 87Ah, 2.9 h (t ₂ )

I _max (I ₁ ): 84Ah, 0.933 h (t ₁ )

Thus K ₂ = 97.674, n ₂ = 1.0335

Step 3)

I _b = 90 A (1 C, I _min ) to 180 A (2 C, I _max )

I _min (I ₂ ): 84Ah, 0.933 h (t ₂ )

I _max (I ₁ ): 80Ah, 0.444 hours (t ₁ )

Thus K ₃ = 115.942, n ₃ = 1.07143

Thereafter, the battery management system may correct the estimated SOC of the battery, that is, by compensating the parameter according to the internal and external factors of the battery (S222), and correcting the SOC of the battery based on the compensated parameter ( S223). Since this is the same as the content described in the first estimation mode, a detailed description thereof will be omitted.

As described above, the present invention can effectively estimate the state of charge of the battery by estimating the state of charge of the battery in different ways according to the charging or discharging mode. In addition, the present invention may correct the state of charge of the battery estimated according to the state of charge or discharge according to internal and external factors, it is possible to accurately estimate the state of charge of the battery.

The battery management system and method for estimating a state of charge of a battery according to the present invention can be modified and applied in various forms within the scope of the technical idea of the present invention and are not limited to the above embodiments. In addition, the embodiments and drawings are merely for the purpose of describing the contents of the invention in detail, not intended to limit the scope of the technical idea of the invention, the present invention described above is common knowledge in the technical field to which the present invention belongs As those skilled in the art can have various substitutions, modifications, and changes without departing from the technical spirit of the present invention, it is not limited to the above embodiments and the accompanying drawings, as well as the claims below. It should be judged by including the claims and the equivalents.

1 is an exemplary view showing the configuration of a schematic system according to an embodiment of the present invention,

2 is an exemplary view illustrating a method for estimating a state of charge of a battery according to an embodiment of the present invention.

3 is a first exemplary view showing a boltzman graph according to an embodiment of the present invention,

4 is a second exemplary view showing a boltzman graph according to an embodiment of the present invention;

5 is a third exemplary view showing a boltzman graph according to an embodiment of the present invention;

6 is an exemplary view showing a peukert graph according to an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

110: voltage detection unit

120: current sensing unit

130: temperature sensing unit

140: control unit

150: SOC estimator

160: SOC correction unit

170: memory

Claims (14)

A controller configured to determine a first estimation mode or a second estimation mode for estimating a state of charge (SOC) of the battery; An SOC estimator configured to estimate an SOC of the battery based on the voltage, current, and temperature of the battery measured according to the determined first estimation mode or the second estimation mode; And A SOC correction unit for correcting the SOC of the battery estimated according to internal and external factors of the battery, The SOC estimator estimates the SOC of the battery using the Boltzman equation based on the voltage, current, and temperature of the battery in the first estimation mode, and the voltage, current, and temperature of the battery in the second estimation mode. Estimate the SOC of the battery using the Peukert equation, The SOC corrector compensates at least one parameter of the Boltzman equation according to internal and external factors of the battery in the first estimation mode, and then corrects the SOC of the battery using the Boltzman equation to which the compensated parameter is applied. And correcting at least one parameter of the Peukert equation according to internal and external factors of the battery in the second estimation mode, and correcting the SOC of the battery using the Peukert equation to which the compensated parameter is applied. The first estimation mode is an initial state in which the battery is not charged or discharged, or the battery is in a charged state, and the second estimation mode is a discharge state of the battery. Management system. delete delete delete delete delete The method according to claim 1, Internal and external factors of the battery, The battery management system for estimating the state of charge of the battery, characterized in that at least one of the internal temperature of the battery during charge and discharge, the number of charge and discharge, aging, charge / discharge current. Determining a first estimation mode or a second estimation mode for estimating a state of charge (SOC) of the battery; Estimating the SOC of the battery based on the voltage, current, and temperature of the battery measured according to the determined first estimation mode or the second estimation mode; And Correcting the SOC of the battery estimated according to internal and external factors of the battery, The estimating the SOC of the battery may include estimating the SOC of the battery using a Boltzman equation based on the voltage, current, and temperature of the battery in the first estimation mode; And Estimating the SOC of the battery using a Peukert equation based on the voltage, current, and temperature of the battery in the second estimation mode; Correcting the SOC of the battery may include compensating at least one parameter of the Boltzman equation according to internal and external factors of the battery in the first estimation mode, and then using the Boltzman equation to which the compensated parameter is applied. Calibrating the SOC; And Compensating at least one parameter of a Peukert equation according to internal and external factors of the battery in the second estimation mode, and then correcting the SOC of the battery using the Peukert equation to which the compensated parameter is applied; Wherein the first estimation mode is an initial state in which the battery is not charged or discharged, or the battery is in a charged state, and the second estimation mode is a discharge state of the battery. . delete delete delete delete delete The method of claim 8, Internal and external factors of the battery, A method for estimating a state of charge of a battery, characterized in that at least one of the internal temperature of the battery during charge and discharge, the number of charge and discharge, aging, charge / discharge current.

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