JP6201899B2 - Battery charge state estimation method and battery charge state estimation device - Google Patents

Description

  The present invention relates to a battery charge state estimation method and a battery charge state estimation device for estimating a state of charge (SOC) of a battery used in a hybrid electric vehicle (HEV) or the like.

  In recent years, hybrid vehicles and electric vehicles using a drive motor driven by electric power as one of the power sources have been widely developed. As a power source for such a drive motor, a battery composed of a large-capacity secondary battery is used. The battery mounted on the hybrid vehicle is charged when the drive motor regenerates power during traveling or by power generation accompanying the rotation of the engine. On the other hand, a battery mounted on an electric vehicle or a plug-in hybrid vehicle is charged from an external power source such as a household commercial power source.

  In the electric vehicle as described above, accurately grasping the SOC indicating the state of charge of the battery is very important for preventing the battery from being overcharged and overdischarged and for accurately communicating the remaining capacity of the battery during traveling to the passenger. Is important to. However, it is difficult to directly detect the state inside the battery.

  Conventionally, various methods are used for estimating the SOC of a battery. For example, the charge / discharge current of the battery is integrated over time to calculate the integrated charge amount and integrated discharge amount, and these integrated charge amount and integrated discharge amount are added to or subtracted from the initial state or the charge amount immediately before the start of charge / discharge. Input the battery input current value and terminal voltage value into the battery charge calculation method (hereinafter referred to as the current integration method) and the battery equivalent circuit model, and sequentially estimate the open circuit voltage of the model. Thus, there is a method for estimating the SOC of the battery from the open circuit voltage (hereinafter referred to as the OCV method).

  However, each of the above methods has advantages and disadvantages.

  In the latter OCV method, the open circuit voltage is calculated from the voltage / current / temperature / battery model. Therefore, the error in the estimated SOC value increases in the current region in the charged or discharged state due to the model error. There is no accumulation of offset current error, which is the sum of errors from the start of discharge.

  On the other hand, since the former current integration method does not require a battery model, the error does not increase even in a large current region, but there is a problem that the offset current error is accumulated with time and the SOC estimation error is deteriorated.

  The latter OCV method does not require constant measurement of charge current and discharge current as in the former current integration method, but an equivalent circuit model of the battery is used to calculate the OCV. There is a problem that an error occurs. This error is particularly noticeable when a large current (for example, 100 A to 200 A) flows.

  On the other hand, although the former current integration method is more accurate than the OCV method in short-term SOC estimation, it requires constant measurement of charging current and discharging current, and further, a current sensor for measuring an input current value. Since there is an error such as a gain error, there is a problem that the error due to the current sensor is integrated with the lapse of time from the start of charge / discharge of the battery, and the SOC estimation accuracy deteriorates.

  In Patent Document 1, for the purpose of calculating such an error of the current sensor, the offset of the current sensor is based on the battery capacity difference between the battery capacity obtained from the integrated current value and the battery capacity obtained from the open circuit voltage. A method for calculating an error and a gain error is disclosed.

JP-A-2005-261130

  By the way, in an electric vehicle equipped with a driving high voltage battery for driving the vehicle, it is necessary to electrically insulate the high voltage power supply system from the vehicle body in order to ensure safety. Sensors are commonly used. However, in the Hall element type current sensor, an offset current error occurs. Therefore, in the SOC estimation using the above-described integration method, the offset current error is accumulated with the lapse of integration time, and the SOC estimation accuracy may be deteriorated. is there.

  Further, the offset current error is estimated to be about 2A, considering that the error is 1% F.S. and the maximum current is about 200A. It can be seen that the SOC estimation result by the long-time current integration method cannot be used in a hybrid vehicle using a battery capacity of about 3 [Ah].

  On the other hand, in the OCV method, the SOC estimation error increases in the current region, particularly in the region where a large current flows, due to the battery model error.

  As described above, in the OCV method, the current integration method is performed in the large current charge / discharge section where the error is large, and the OCV method estimation result is obtained in the section where the integration time increases or the charge / discharge current decreases and the OCV method accuracy can be expected. The logic to choose is qualitatively said. However, since it is difficult to accurately estimate the offset error, it is impossible to correctly estimate the two estimation method errors.

  The present invention has been made in view of the above point, and cancels the offset error component by utilizing the fact that the signs of the current integration method error and the OCV method error are contrary to the offset error. An object of the present invention is to accurately estimate the state of charge of a battery without the need to accurately estimate an offset current value.

  The offset error component is canceled by utilizing the fact that the signs of the current integration method error and the OCV method error are opposite to the offset error. According to this method, it is not necessary to accurately estimate the offset current value.

  Specifically, the first invention is directed to a battery charge state estimation method for estimating the charge state of the battery based on the charge / discharge current and terminal voltage of the battery, and has taken the following solution.

In other words, according to the first aspect of the present invention, integration method charging is performed in which the charge / discharge current of the battery detected by the current sensor is integrated over time, and the integration method estimation charge state, which is the state of charge of the battery, is estimated based on the time integration value. Obtaining an open circuit voltage of the battery based on a state estimation step, a terminal voltage of the battery detected by the voltage sensor, a charge / discharge current detected by the current sensor, and an equivalent circuit model of the battery; An OCV method charge state estimation step for estimating an OCV method estimated charge state that is a charge state of the battery from a voltage, and an average for obtaining an estimated charge state average value that is an average value of the integration method estimated charge state and the OCV method estimated charge state a value acquisition step, the time integrated value der from charging and discharging the start of the battery of the error in the integration method estimated charge state resulting from the current sensor Integration method error, upper Symbol time change is OCV method error from charging and discharging the start of the battery of the error in the OCV method estimated charge state resulting from the equivalent circuit model, as well as the integration method error and OCV method error of the mean An error acquisition step for obtaining an error average that is a time change of the above-mentioned method , and the integration method estimated charge state , the OCV method estimated charge state based on the integration method error , the OCV method error, and the error average obtained in the error acquisition step Alternatively , a charge state selection step of selecting an estimated charge state average value and setting the selected estimated charge state to the state of charge of the battery is provided.

According to the first invention, the state of charge of the battery is estimated by the current integration method and the OCV method, and the time change from the start of battery charge / discharge in both methods is obtained. When obtaining the time variation of the error in the current integration method, the time variation of the error caused by the current sensor, which is a dominant factor, is obtained. On the other hand, when obtaining the time variation of the error in the OCV method, the time variation of the error caused by the equivalent circuit model of the battery, which is the main factor, is obtained. Therefore, it is possible to accurately obtain the time change of the error in each estimation method. Then, the estimated charging state by the smaller estimation method among the obtained time variations of the error is selected and set as the charging state of the battery. As described above, the time variation of the error by each estimation method is obtained with high accuracy, and the estimated charge state by the estimation method with a small error is selected as the battery charge state, so the battery charge state is estimated with higher accuracy than before. it can be.

In here, the sign of the integration method error and OCV method error is noted a contradiction (positive or negative), than the integrated method error and OCV method error, which may mean both of these errors is minimized.

Therefore, according to the first invention, in addition to the current integration method and the OCV method, an estimated charge state average value which is an average value of the charge states estimated by both methods is obtained, and further, the integration method error and the OCV method error are obtained. In addition to the above, an error average which is an average of these is obtained. Then, an estimated charge state is selected by the method of the smallest error among these three error time variations. Therefore, the state of charge of the battery can be estimated with higher accuracy.

According to a second aspect , in the first aspect, in the charge state selection step, the selection is made based on an elapsed time from the start of charge / discharge of the battery.

According to the second aspect , since the estimated charge state is selected based on the elapsed time from the start of charge / discharge of the battery, the charge state of the battery can be estimated easily and with relatively high accuracy.

According to a third invention, in the first or second invention, in the charge state selection step, the integration method estimated charge state is selected from a start of charge / discharge of the battery to a lapse of a predetermined time. .

According to the third aspect of the invention, the integration method error is obtained by integrating the sensor error of the current sensor over time. That is, the integration method error is the smallest at the start of charging / discharging (current integration) of the battery. Therefore, from the start of charge / discharge (current integration) of the battery to the elapse of a predetermined time, the state of charge of the battery can be estimated with higher accuracy by selecting the estimated charge state by the current integration method with the smallest error.

The fourth aspect of the present invention is directed to a battery state-of-charge estimation device that estimates the state of charge of a battery based on the terminal voltage and charge / discharge current of the battery, and has taken the following solution.

That is, the fourth aspect of the invention relates to a current sensor that detects the charge / discharge current of the battery, a voltage sensor that detects the terminal voltage of the battery, and the charge / discharge current detected by the current sensor. An integration method charging state estimation means for estimating an integration method estimated charging state which is a charging state of the battery based on an integration value, a terminal voltage detected by the voltage sensor, a charging / discharging current detected by the current sensor, and the above calculating the open circuit voltage based on a battery of equivalent circuit model, the OCV method charged state estimating means from the open circuit voltage estimating the OCV method estimated charge state is a state of charge of the battery, the accumulation method estimated charge state and an average value calculation means for calculating the estimated charge state average is OCV method average value of the estimated state of charge, the accumulation method estimation caused by said current sensor Time integrated value in the form of the integration method errors from charge and discharge start of the battery state of charge error, at the time the change from charging and discharging the start of the battery above Symbol error of the OCV method estimated charge state resulting from the equivalent circuit model An OCV method error , an error acquisition means for obtaining an error average that is a temporal change in the average value of the integration method error and the OCV method error , the integration method error , the OCV method error and the error obtained by the error acquisition means Charge state selection means for selecting the integration method estimated charge state , the OCV method estimated charge state or the estimated charge state average value based on an average, and setting the selected estimated charge state to the charge state of the battery. And

According to the 4th invention, there can exist an effect similar to 1st invention.

  As described above, according to the present invention, the state of charge of the battery can be accurately estimated.

It is a block diagram which shows the structure of the battery charge condition estimation apparatus which concerns on embodiment of this invention. (A) is a block diagram of the control of the current integration method charging state estimation unit, (b) is a block diagram of the control of the OCV method charging state estimation unit, (c) is a diagram showing an equivalent circuit model of the battery. is there. (A) is a control block diagram for calculating an integration method charging state estimation error, (b) is a control block diagram for calculating an OCV method charging state estimation error, and (c) is a battery It is a figure which shows an equivalent circuit model. It is a figure which shows the control flow of a charge condition estimation apparatus. It is a figure which shows the relationship between an integration method charging state estimation error and OCV method charging state estimation error, (a) is a figure which shows the case where OCV method charging state estimation error is comparatively large, (b) is OCV method It is a figure which shows the case where a charging condition estimation error is comparatively small. It is a figure which shows an example of the time transition of the charge condition estimation error in each method of a battery. It is a block diagram which shows the structure of the charge condition estimation apparatus which concerns on the modification of embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the following description of preferable embodiment is only an illustration essentially, and is not intending restrict | limiting this invention, its application thing, or its use.

  FIG. 1 is a block diagram illustrating a configuration of a battery charge state estimation device 1 (hereinafter simply referred to as a charge state estimation device 1) according to the present embodiment. The charging state estimation device 1 is a device that estimates the charging state of a battery, particularly a battery BAT mounted on a HEV. The battery BAT is composed of a secondary battery such as a lead storage battery and is electrically insulated from the vehicle body.

The charging state estimation device 1 includes a current sensor 3 and a voltage sensor 5 that detect a charging / discharging current I and a terminal voltage VBAT of the battery BAT, respectively, and a current integration method charging state estimation that estimates a charging state of the battery BAT by a current integration method. Estimated by the unit 7 (accumulation method charge state estimation means), the OCV method charge state estimation unit 9 (OCV method charge state estimation means) for estimating the charge state of the battery BAT by the OCV method, and the current integration method charge state estimation unit 7 The average of the charged state of the battery BAT (hereinafter referred to as the integration method estimated charge state SOC_I) and the state of charge of the battery BAT estimated by the OCV method charge state estimation unit 9 (hereinafter referred to as the OCV method estimated charge state SOC_V). Average value calculation unit 11 (average value calculation means) for calculating estimated charge state average value SOC_VI, which is a value, An error estimation unit 13 (error acquisition means) for estimating the error of the determination method, and based on the error estimated by the error estimation unit 13, the integration method estimated charge state SOC_I, the OCV method estimated charge state SOC_V or the estimated charge state average And a multiplexer 15 that selects the value SOC_VI and sets the battery BAT in a charged state.

  The current sensor 3 is a Hall element type because the battery BAT is electrically insulated from the vehicle body as described above. This current sensor 3 is connected in parallel with a current integration method charging state estimation unit 7, an OCV method charging state estimation unit 9 and an error estimation unit 13, and transmits a signal indicating the detected charging / discharging current I to these units. The voltage sensor 5 is connected to an OCV method charging state estimation unit 9, and transmits a signal indicating the detected terminal voltage to the OCV method charging state estimation unit 9.

  The current integration method charging state estimation unit 7 calculates the integration method estimation charging state SOC_I based on the signal transmitted from the current sensor 3. FIG. 2A is a block diagram of the control of the current integration method charging state estimation unit 7. Based on the charge / discharge current value I detected by the current sensor 3 and the known battery capacity Cap of the battery BAT, the current integration method charging state estimation unit 7 calculates the time integration value ΔSOC_I (ΔSOC_I = (Idt / Cap) is obtained. On the other hand, the current integration method charging state estimation unit 7 acquires the charging state initial value SOC0 of the battery BAT from the OCV method charging state estimation unit 9. Then, current integration method charging state estimation unit 7 adds time integration value ΔSOC_I to charging state initial value SOC0 to obtain integration method estimated charging state SOC_I of battery BAT, and outputs the result to multiplexer 15.

  The OCV method charging state estimation unit 9 calculates the OCV method estimated charging state SOC_V based on the signals transmitted from the current sensor 3 and the voltage sensor 5. FIG. 2B is a block diagram of the control of the OCV method charging state estimation unit 9. In the OCV method charging state estimation unit 9, an equivalent circuit model of the battery BAT shown in FIG. 2C is set in advance, and the resistance value R of the battery BAT set by the equivalent circuit model, the current sensor 3, and Based on the charging / discharging current value I and the terminal voltage value VBAT detected by the voltage sensor 5, the open circuit voltage OCV (OCV = VBAT-IR) of the battery BAT is calculated. Here, the OCV method charging state estimation unit 9 stores an OCV-SOC map indicating the correspondence between the open circuit voltage OCV and the charging state SOC of the battery BAT. The OCV method charge state estimation unit 9 refers to this map, acquires the OCV method estimated charge state SOC_V of the battery BAT corresponding to the calculated open circuit voltage OCV, and outputs it to the multiplexer 15.

  The average value calculation unit 11 is connected to the current integration method charging state estimation unit 7 and the OCV method charging state estimation unit 9, and acquires the integration method estimation charging state SOC_I and the OCV method estimation charging state SOC_V. Then, the average value calculation unit 11 calculates an estimated charge state average value SOC_VI (SOC_VI = (SOC_V + SOC_I) / 2), which is an average value of the estimated charge states SOC_I and SOC_V, and outputs the calculated value to the multiplexer 15.

  The error estimation unit 13 includes an integration method charging state estimation error SOC_Ierr, which is a time integration value from the start of charging / discharging of the battery BAT, due to an error in the integration method estimated charging state SOC_I caused by the offset error of the current sensor 3, and FIG. c) OCV method charge state estimation error SOC_Verr which is a time change from the start of charging / discharging of battery BAT due to the error of OCV method estimated charge state SOC_V caused by the equivalent circuit model of battery BAT shown in FIG. An error average SOC_VIerr that is an average value of errors is obtained.

  FIG. 3A shows a block diagram of control for calculating the integration method charging state estimation error SOC_Ierr. The error estimation unit 13 obtains an integration method charging state estimation error SOC_Ierr (SOC_Ierr = ∫Ierrdt / Cap) from the time integration value of the current error Ierr resulting from the offset error of the current sensor 3.

  On the other hand, FIG. 3B shows a block diagram of control for calculating the OCV method charging state estimation error SOC_Verr. In the error estimation unit 13, an equivalent circuit model of the battery BAT shown in FIG. The resistance in this equivalent circuit model is represented by the sum of the resistance true value Rref and the resistance error Rerr, while the charge / discharge current is the sum of the current true value Iref and the current error Ierr resulting from the offset error of the current sensor 3. It is represented by

  In this equivalent circuit model, the error estimation unit 13 calculates an open circuit voltage error OCVerr (OCVerr = {VBAT− (Iref + Ierr) (R + Rerr)} − (VBAT−Iref · R) = − Ierr · Rref + (Iref + Ierr) Rerr). To do. In addition, since Rerr can take a positive or negative value, the open circuit voltage error OCVerr is -Ierr · Rref− (Iref + Ierr) | Rerr | ≦ open circuit error OCVerr ≦ −Ierr · Rref + (Iref + Ierr) | Rerr | Can take a range value. Here, | Rerr | is the absolute value of Rerr.

  Further, the error estimating unit 13 obtains the OCV method estimated charging state SOC_V from the OCV method charging state estimating unit 9, and refers to the OCV-SOC map to determine the slope of OCV in the OCV method estimated charging state SOC_V (dOCV / dSOC). ) | SOC is obtained. Then, the error estimation unit 13 calculates the OCV method charging state estimation error SOC_Verr (SOC_Verr = (dOCV / dSOC) OCVerr) based on the open circuit voltage error OCVerr and the slope (dOCV / dSOC) | SOC.

  Further, the error estimating unit 13 calculates the error average SOC_VIerr (SOC_VIerr = (SOC_Ierr + SOC_Verr) / 2) of the integration method charging state estimation error SOC_Ierr and the OCV method charging state estimation error SOC_Verr.

  Then, error estimation unit 13 outputs calculated integration method charging state estimation error SOC_Ierr, OCV method charging state estimation error SOC_Verr, and error average SOC_VIerr to multiplexer 15.

  The multiplexer 15 receives one of the inputs from the current integration method charging state estimation unit 7, the OCV method charging state estimation unit 9, and the average value calculation unit 11 based on the selection control input from the error estimation unit 13. Output as an estimated charge state of the battery BAT. Specifically, the multiplexer 15 determines a magnitude relationship among the integration method charging state estimation error SOC_Ierr, the OCV method charging state estimation error SOC_Verr, and the error average SOC_VIerr input from the error estimation unit 13, and corresponds to the smallest error. The estimated charging state is selected and the selected estimated charging state is output as the charging state of the battery BAT.

  Next, the operation of the charging state estimation device 1 will be described with reference to the flowchart shown in FIG.

  When the charging / discharging of the battery BAT starts, the charging state estimation device 1 acquires the estimated charging state previous value SOC (−1) estimated by the OCV method charging state estimation unit 9 at the end of the previous charging / discharging of the battery BAT, The OCV slope (dOCV / dSOC) | SOC with respect to the SOC at the estimated charge state previous value SOC (-1) is calculated with reference to the OCV-SOC map of the OCV method charge state estimation unit 9 (step S1).

  Next, the charging state estimation device 1 calculates the open circuit voltage error OCVerr based on the charging / discharging current I and the terminal voltage VBAT detected by the current sensor 3 and the voltage sensor 5, respectively, and an upper limit value OCVerrU (OCVerrU = − Ierr · Rref + (Iref + Ierr) | Rerr |) and the lower limit value OCVerrL (OCVerrL = −Ierr · Rref− (Iref + Ierr) | Rerr |) are calculated (step S3). At this time, it is assumed that the current error Ierr resulting from the offset error of the current sensor 3 is Ierr> 0.

  Subsequently, the state-of-charge estimating apparatus 1 determines the OCV slope (dOCV / dSOC) | SOC with respect to the SOC (−1) calculated in step S1 and the open circuit voltage error OCVerr calculated in step S3. An OCV method charging state estimation error SOC_Verr is calculated (step S5).

  On the other hand, the charging state estimation device 1 determines whether or not the upper limit value OCVerrrU of the open circuit voltage error OCVerr calculated in step S3 is smaller than 0 (step S7).

  When the charging / discharging current I of the battery BAT is relatively large, when the charging rate of the battery BAT is relatively small, or when both of these conditions are satisfied, the upper limit value OCVerrU of the open circuit voltage error OCVerr is 0 or more. (NO in step S7). In this case, the charging state estimation device 1 does not select the error average SOC_VIerr, and the absolute value | SOC_Ierr | of the integration method charging state estimation error SOC_Ierr is from the absolute value | OCVerrL of the lower limit value OCVerrL of the OCV method charging state estimation error SOC_Verr. Is also smaller (step S9).

  When the absolute value | SOC_Ierr | of the integration method charging state estimation error SOC_Ierr is smaller than the absolute value | OCVerrL | of the lower limit value OCVerrL | of the OCV charging state estimation error SOC_Verr (YES in step S9), FIG. As shown, since the integration method charging state estimation error SOC_Ierr indicated by the broken line is the smallest, the charging state estimation device 1 selects the integration method estimated charging state SOC_I as the charging state of the battery BAT (step S11), and this integration method estimation. The state of charge SOC_I is output as the state of charge of the battery BAT, and the process returns to step S1.

  On the other hand, when the absolute value | SOC_Ierr | of the integration method charging state estimation error SOC_Ierr is larger than the absolute value | OCVerrL | of the lower limit value OCVerrL | of the OCV method charging state estimation error SOC_Verr (NO in step S9), the OCV method charging state Since the estimation error SOC_V is the smallest, the charging state estimation device 1 selects the OCV method estimated charging state SOC_V as the charging state of the battery BAT (step S13), and outputs this OCV method estimated charging state SOC_V as the charging state of the battery BAT. To do. Then, the charging state estimation device 1 sets the integration method charging state estimation error SOC_Ierr to 0, resets the error due to the current integration method (step S15), and returns the process to step S1.

  In step S7, when the charging / discharging current I of the battery BAT is relatively small, the charging rate of the battery BAT is relatively large, or both of these conditions are satisfied, the upper limit of the open circuit voltage error OCVerr There is a high possibility that the value OCVerrU is smaller than 0 (YES in step S7). In this case, as shown in FIG. 5 (b), the charging state estimation device 1 has a relatively small OCV method charging state estimation error SOC_Verr indicated by a one-dot chain line, and the average error SOC_VIerr is the smallest. The value SOC_VI is selected (step S17), and the estimated charge state average value SOC_VI is output as the charge state of the battery BAT (step S19). And the charge condition estimation apparatus 1 returns a process to step S1.

  FIG. 6 is a diagram illustrating an example of a time transition of a charging state estimation error in each method of the battery BAT. It is. In FIG. 6, the vertical axis indicates the magnitude of the error, and the horizontal axis indicates the elapsed time t from the start of charging / discharging of the battery BAT. In this example, the upper limit SOCerrU of the OCV method charging state estimation error SOC_Verr is greater than zero. In FIG. 6, the integration method charging state estimation error SOC_Ierr is indicated by a broken line, the OCV method charging state estimation error SOC_Verr is indicated by a broken line, and the error average SOC_VIerr is indicated by a broken line.

  When the battery BAT starts charging and discharging, the charging state estimation device 1 selects the integration method estimated charging state SOC_I because the integration method charging state estimation error SOC_Ierr is the smallest, and sets the charging state of the battery BAT.

  When the error due to the offset error of the current sensor is integrated over time, the integration method charging state estimation error SOC_Ierr gradually increases, and at the elapsed time t1, the integration method charging state estimation error SOC_Ierr becomes larger than the error average SOC_VIerr. The average SOC_VIerr is the smallest. Therefore, the charging state estimation device 1 selects the estimated charging state average value SOC_VI and sets the charging state of the battery BAT.

  When the elapsed time t2 is reached, the error average SOC_VIerr becomes larger than the integration method charging state estimation error SOC_Ierr, and the integration method charging state estimation error SOC_Ierr becomes the smallest. Therefore, the charging state estimation device 1 selects the integration method estimated charging state SOC_I and sets the charging state of the battery BAT.

  When the elapsed time t3 is reached, the integration method charging state estimation error SOC_Ierr again becomes larger than the error average SOC_VIerr, and the error average SOC_VIerr becomes the smallest. Therefore, the charging state estimation device 1 selects the estimated charging state average value SOC_VI and sets the charging state of the battery BAT.

  Then, at the elapsed time t4, the integration method charging state estimation error SOC_Ierr increases, and the error average SOC_VIerr becomes larger than the OCV method charging state estimation error SOC_Verr. At this timing, since the OCV method charging state estimation error SOC_Verr is the smallest, the charging state estimation device 1 selects the OCV method estimated charging state SOC_V and sets the battery BAT to the charging state. At the same time, the charging state estimation device 1 resets the integration method charging state estimation error SOC_Ierr to 0.

  The charging state estimation device 1 repeats the above processing while the battery BAT is charging / discharging.

  As described above, the charging state estimation device 1 constantly monitors the time transition of the integration method charging state estimation error SOC_Ierr, the OCV method charging state estimation error SOC_Verr, and the error average SOC_VIerr from the start of charging / discharging of the battery BAT, and is the smallest. By selecting the state of charge estimated by the method corresponding to the error, the state of charge can be accurately estimated.

-Effects of the embodiment of the invention-
According to the above embodiment, the state of charge of the battery BAT is estimated by the current integration method and the OCV method, and the time change from the start of battery charge / discharge in both methods is obtained. When obtaining the time change of the error in the current integration method, the time change of the integration method charging state estimation error SOC_Ierr caused by the current sensor, which is a dominant factor, is obtained. On the other hand, when obtaining the time variation of the error in the OCV method, the time variation of the error due to the equivalent circuit model of the battery BAT, which is the main factor, is obtained. Therefore, it is possible to accurately obtain the time change of the error in each estimation method. Then, the estimated charging state by the smaller estimation method among the obtained time variations of the error is selected, and the charging state of the battery BAT is set. In this way, the time variation of the error by each estimation method is obtained with high accuracy, and the estimated charge state by the estimation method with a small error is selected as the charge state of the battery BAT. Therefore, the charge state of the battery BAT is more accurate than before. Can be estimated.

  Here, when the charging / discharging current of the battery BAT is relatively small, depending on the time elapsed from the start of charging / discharging of the battery BAT, the average of these values may be greater than the integration method charging state estimation error SOC_Ierr and the OCV method charging state estimation error SOC_Verr A certain error average SOC_VIerr may be the smallest.

  Therefore, according to the above embodiment, in addition to the current integration method and the OCV method, an estimated charge state average value SOC_VIerr that is an average value of the charge state estimated by both methods is obtained, and further, the integration method charge state estimation error SOC_Ierr Then, an error average SOC_VIerr, which is an average of the SOCV method charging state estimation error SOC_Verr, is obtained. Then, an estimated charge state is selected by the method of the smallest error among these three error time variations. Therefore, the state of charge of the battery can be estimated with higher accuracy.

  Moreover, according to the said embodiment, since the estimated charge state is selected based on the elapsed time t from the start of charging / discharging of the battery BAT, the charge state of the battery BAT can be estimated easily and with relatively high accuracy. .

  Further, according to the embodiment, the integration method charging state estimation error SOC_Ierr is obtained by integrating the offset error of the current sensor 3 with time. That is, at the charging / discharging start stage of the battery BAT, the integration method charging state estimation error SOC_Ierr is the smallest. Therefore, from the start of charging / discharging of the battery BAT to the elapse of a predetermined time, the charging state of the battery BAT can be estimated with higher accuracy by selecting the estimated charging state SOC_I by the current integration method with the smallest error.

( Reference example )
FIG. 7 is a block diagram showing a configuration of the battery charge state estimation device 2 according to a modification of the embodiment. This charging state estimation device 2 differs from the charging state estimation device 1 according to the above embodiment in that the average value calculation unit 11 is not provided. The charging state estimation device 2 estimates the integration method charging state estimation error SOC_Ierr and the OCV method charging state estimation error SOC_Verr in the error estimation unit 13, and the charging estimated by the estimation method corresponding to the smaller error in the multiplexer 15. Let the state be the state of charge of the battery BAT.

  Thus, while simplifying the configuration, it is possible to perform estimation with higher accuracy than estimation of the state of charge of the battery BAT using only the current integration method or the OCV method.

(Other embodiments)
In the above embodiment, the integration method estimated charge state SOC_I, the OCV method estimated charge state SOC_V, or the estimated state average value SOC_VI is selected based on the integration method charge state estimation error SOC_Ierr, the OCV method charge state estimation error SOC_Verr, and the error average SOC_VIerr. However, the present invention is not limited to this, and the selection may be made based on the elapsed time t from the start of charging / discharging of the battery BAT. In this case, since the selection is made based only on the elapsed time, the control can be simplified.

  As described above, the battery charge state estimation method and the battery charge state estimation device according to the present invention can be applied to a use for estimating the charge state of the battery with higher accuracy.

1 Charge state estimation device (battery charge state estimation device)
3 Current sensor 5 Voltage sensor 7 Current integration method charge state estimation unit (integration method charge state estimation means)
9 OCV method charge state estimation unit (OCV method charge state estimation means)
11 Average value calculation unit (average value calculation means)
13 Error estimation part (error acquisition means)
15 Multiplexer (charging state selection means)
BAT battery

Claims (4)

A battery charge state estimation method for estimating a charge state of the battery based on a charge / discharge current and a terminal voltage of the battery,
An integration method charging state estimation step of integrating the charging / discharging current of the battery detected by a current sensor over time, and estimating an integration method estimation charging state that is a charging state of the battery based on the time integration value;
An open circuit voltage of the battery is obtained based on a terminal voltage of the battery detected by the voltage sensor, a charge / discharge current detected by the current sensor, and an equivalent circuit model of the battery, and the battery's open circuit voltage is determined from the open circuit voltage. OCV method charge state estimation step of estimating the charge state of the OCV method estimated charge state;
An average value obtaining step for obtaining an estimated charge state average value which is an average value of the integration method estimated charge state and the OCV method estimated charge state;
The cumulative method estimated time integrated value in the form of the integration method error from charging and discharging the start of the battery error in a charged state, the upper Symbol error of the of the OCV method estimated charge state resulting from the equivalent circuit model due to said current sensor An error obtaining step of obtaining an OCV method error that is a time change from the start of charge / discharge of the battery, and an error average that is a time change of an average value of the integration method error and the OCV method error ;
Based on the integration method error , OCV method error and error average obtained in the error acquisition step, the integration method estimated charge state , OCV method estimated charge state or estimated charge state average value is selected, and the selected estimated charge is selected. And a charging state selection step for setting the state of the battery to a charging state of the battery. The battery charge state estimation method according to claim 1 ,
In the charging state selection step, the battery charging state estimation method is selected based on an elapsed time from the start of charging / discharging of the battery. The battery charge state estimation method according to claim 1 or 2 ,
In the charge state selection step, the battery charge state estimation method is characterized in that the integration method estimated charge state is selected from the start of charging / discharging of the battery to a lapse of a predetermined time. A battery charge state estimation device for estimating a charge state of a battery based on a terminal voltage and a charge / discharge current of the battery,
A current sensor for detecting the charge / discharge current of the battery;
A voltage sensor for detecting the terminal voltage of the battery;
Integration method charging state estimation means for integrating the charging / discharging current detected by the current sensor over time, and estimating the integration method estimation charging state that is the charging state of the battery based on the time integration value;
An open circuit voltage is obtained based on the terminal voltage detected by the voltage sensor, the charge / discharge current detected by the current sensor, and the equivalent circuit model of the battery, and the OCV that is the state of charge of the battery is determined from the open circuit voltage. OCV method charging state estimating means for estimating the method estimating charging state;
Average value calculating means for obtaining an estimated charge state average value that is an average value of the integration method estimated charge state and the OCV method estimated charge state;
The cumulative method estimated time integrated value in the form of the integration method error from charging and discharging the start of the battery error in a charged state, the upper Symbol error of the of the OCV method estimated charge state resulting from the equivalent circuit model due to said current sensor An error acquisition means for obtaining an OCV method error that is a time change from the start of charge / discharge of the battery, and an error average that is a time change of an average value of the integration method error and the OCV method error ;
Based on the integration method error , OCV method error and error average obtained by the error acquisition means, the integration method estimated charge state , OCV method estimated charge state or estimated charge state average value is selected, and the selected estimated charge state is A battery charge state estimation device comprising: a charge state selection unit configured to charge the battery.

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