State of charge determination device and method for determining a state of charge value of a battery device

Abstract

The invention is directed to a method for determining an actual state of charge value (Qc) of a battery device (202), which includes receiving a current value (I(t)) indicative of an electric current provided to, or by, the battery device as a function of time, determining a first state of charge value (Qk) of the battery device at a first instant (tk), determining, an error current value (Ierr,k) indicative of a deviation between a real current value (Ireal) and the received current value (I(t)), determining a corrected current value (Icorr,k(t)) using the received current value (I(t)) and the determined error current value (Ierr,k) and determining the actual state of charge value (Qc) of the battery device using the corrected current value (Icorr(t)) and the first state of charge value (Qk) with an improved accuracy.

Description

[0001] State of charge determination device and method for determining a state of charge value of a battery device

[0002] FIELD OF THE INVENTION

[0003] The present invention is directed to a state of charge determination device and to a method for monitoring and / or controlling a battery device. The invention is also directed to a battery assembly and to a computer program.

[0004] BACKGROUND OF THE INVENTION

[0005] In any type of battery device, the state of charge, or state of charge value, is an important quantity for controlling the battery device, especially to avoid over-charging and over-dis- charging, but also to be able to plan ahead how much energy can be stored or discharged from the battery. The state of charge value of a battery device is typically calculated by coulomb tracking, which involves measuring or otherwise determining the current that has been provided to, or by, the battery device. Providing electric current by the battery device lowers the state of charge value, whereas providing electric current to the battery device increases the state of charge value. However, the value of the electric current is usually obtained from a current sensor, which typically bears a certain error. Thus, the estimated state of charge value deviates from the true state of charge value. Another reason for a mismatch between the estimated and the true state of charge is a self-discharge behavior, where a cell of the battery device continuously discharges without creating an external, measurable, electric current.

[0006] Regardless of the cause of the deviation in current, such deviations accumulate over time, possibly leading to unphysical computed state of charge values (e.g., negative state of charge values or state of charge values exceeding the capacity of the battery device).

[0007] The established solution is to define characteristic points or ranges in the discharge-charge cycle of the battery which allow to determine the state of charge value to good accuracy. BASF SE 240115

[0008] Once the battery reaches on of said characteristic points or ranges, the state of charge value is reset to the new value at that point, and further calculations of the state of charge value refer to the latest reset value. These characteristic points or ranges are also referred to as charge correction points or ranges.

[0009] An example of the use of charge correction points, referred to as correction drift points, is presented in the document “Diagnosing State of Charge Calculation Jumps”, document revision 1 .1 ., by Ewert Energy Systems, INC, updated on 06 / 07 / 2018.

[0010] SUMMARY OF THE INVENTION

[0011] However, this hard reset approach creates stepwise changes in the state of charge value profile over time. Moreover, this hard reset approach does not deliver a projected correction. Despite the correction at the correction point, the faulty current measurements will still be used to update the state of charge value and the estimated state of charge value will continue to drift away from the real value. In addition, a large deviation might cause a battery control system to stop the charging phase too early or too late, which might lead to the battery operating in unauthorized operating ranges that might cause damage to the battery. It would thus be beneficial to enable a more reliable operation of the battery by providing a correction of the measured current during ongoing battery operation, which is the basis for a stable control of the battery.

[0012] Thus, it is an object of the present invention to provide a method and a device for monitoring and / or controlling a battery device with increased accuracy.

[0013] According to a first aspect of the present invention, a method for monitoring and / or controlling a battery device is disclosed. The method of the first aspect comprises:

[0014] - receiving a current value indicative of an electric current provided to, or by, the battery device as a function of time;

[0015] - determining a first state of charge value of the battery device at a first instant;

[0016] - determining an error current value indicative of a deviation between a real current value and the received current value; BASF SE 240115

[0017] - determining a corrected current value using the determined current value and the determined error current value;

[0018] - determining the actual state of charge value of the battery device using the corrected current value and the first state of charge value; and

[0019] - providing the actual state of charge value for monitoring and / or controlling the battery device.

[0020] Receiving the current value may also include initiating or otherwise causing the determination of the current value, generating, selecting, sending or otherwise ascertaining or acquiring the current value. Determining the first state of value may also include estimating, generating or otherwise ascertaining or acquiring the first state of charge value. Determining the error current value may also include estimating, generating or otherwise ascertaining or acquiring the error current value. Determining the corrected current value may also include calculating, estimating, generating or otherwise ascertaining or acquiring the error current value.

[0021] According to the method of the first aspect, the received current value, for example, a current value determined and provided by a current sensor device or received from any other intermediate device, and which might differ from the real current value provided by, or to, the battery device, is modified by an error current value that is indicative of an error associated to the current sensor. Using the error current value, a corrected current value is obtained. The corrected current value, in combination with the estimated first state of charge value, is used to determine the actual state of charge value, for instance using coulomb tracking.

[0022] Thus, according to the method of the first aspect, a correction quantity is provided to correct the received current value, which can be then used to determine the actual state of charge value, for instance until another state of charge value is estimated, for example at a given charge correction point. This improved knowledge of the actual state of charge value is used to monitor the battery device more accurately and for controlling the operation of the battery in an improved manner, for instance by avoiding the operation of the battery in unauthorized ranges.

[0023] In the following, embodiments of the method of the first aspect will be disclosed. BASF SE 240115

[0024] Preferably, the actual state of charge value of the battery device is determined as the sum of the first state of charge value determined at the first instant and an integrated corrected current provided to, or by, the battery device between the first instant tk and an actual instant tc. An example of said determination is given by: wherein Qc is the actual state of charge value, Qk is the first state of charge value, tk is the first instant, at which the first state of charge value Qk has been determined, tcis the actual or current instant, and lCorr,k(t) is the corrected current value.

[0025] The corrected current value can be defined as: corr,k ) ^(0 ^err,k wherein l(t) is the received current value as a function of time and lerr.k is the estimated error current value.

[0026] In different embodiments, the error current value can be estimated or otherwise determined in different ways, e.g., by analyzing the current sensor, inferred from manufacturer's specifications, or by comparison with other similar sensors, for example by determining a statistical average value using a plurality of sensors and determining a deviation of the respective determined values from the statistical average value.

[0027] In a preferred embodiment of the method of the first aspect, the method further includes:

[0028] - determining (e.g., estimating, generating or otherwise ascertaining) a subsequent state of charge value of the battery device at a subsequent instant or at a plurality of subsequent instants;

[0029] - determining (e.g., calculating, generating or otherwise ascertaining) an error correction term that is proportional to a difference of an integrated corrected current value provided to, or by, the battery device between the first instant and the subsequent instant and a difference between the first state of charge value and the subsequent state of charge value; BASF SE 240115

[0030] - determining (e.g., estimating, generating or otherwise ascertaining) a subsequent error current value using the error current value and the calculated error correction term;

[0031] - determining (e.g., calculating, generating or otherwise ascertaining) a subsequent corrected current value using the received current value (l(t)) and the determined subsequent error current value; and wherein

[0032] - the determination of the actual state of charge value of the battery device is performed using the subsequent corrected current value and the subsequent state of charge value.

[0033] Thus, in an embodiment, the error correction term CT is calculated as: wherein C is a proportionality factor, lCorr,k(t) is the corrected current value tk is the first instant, tk+i is the subsequent instant, Qk is the first state of charge value determined at the first instant and Qk+i is the subsequent state of charge value determined at the subsequent instant.

[0034] Preferably a proportionality factor used in the step of calculating the error correction term is given by a weighing factor divided by a time interval.

[0035] The subsequent error current value lerr,k+i can be estimated using the error current value lerr.k and the calculated error correction term CT. For example, in an embodiment, the subsequent error current value can be determined as follows:

[0036] The subsequent corrected current value lcorr,k+i(t), can be determined using the received current value (l(t)) and the estimated subsequent error current lerr,k+i value as follows: and the actual state of charge value Qcat an instant tc, where tcis later point in time with respect to tk+i , can be calculated as: BASF SE 240115

[0037] Thus, the error current value can be updated for every subsequent state of charge value ascertained, received, calculated or otherwise estimated at a subsequent point in time.

[0038] Preferably for the step of determining or calculating the error correction term, the proportionality factor C is given by a weighing factor W divided by a time interval At, such that:

[0039] In an embodiment, the time interval corresponds to the full interval between the first instant tk and the subsequent instant tk+i . The same applies to further subsequent instants tk+2, tk+3, etc., wherein the time interval can be defined as the difference between two consecutive instants tn-tn-i. However, in another embodiment, the time interval At corresponds to an active time span between an instant (e.g., tk) and subsequent instant relative to said instant (e.g., tk+i), during which the received or otherwise ascertained current value (l(t)) deviates from zero by at least a predetermined current threshold value.

[0040] The time span between two consecutive instants tk and tk+i may include active operation time of the battery device (charge and discharge), but it may also include idle phases, during which no current is flowing. Preferably, the current is set to zero during these idle phases regardless of the actually measured current, which can be different from zero. In these cases, preferably only the active time of the time span is taken into account for the determination of the time interval, which can be referred to as active time interval. For instance, in an embodiment, the active time interval Atactive.k is obtained by integrating the following equation: where Ithreshoid die is the predetermined current threshold value.

[0041] The weighing factor can be varied to account for different errors during charge and discharge, or different errors depending on the electric current value. Here, it is noted that BASF SE 240115 typically, the current value is defined as being positive during a charging phase of the battery device (electric current is provided to the battery device) and is defined as being negative during a discharging phase of the battery device (electric current is provided to the battery device). Alternatively, the current value can be defined as positive during a discharging phase and negative during a charging phase.

[0042] In a particular preferred embodiment, the determination or estimation of the first state of charge value at the first instant and, optionally, the determination or estimation of any other subsequent state of charge value at respective subsequent instants, is performed when the battery device is operating at predetermined charge correction ranges, in which the state of charge value of the battery device is correlatable to a value of a predetermined operational variable of the battery device. The predetermined charge correction ranges or charge correction points referto those points during operation of the battery device in which the true state of charge of the battery device can be determined or estimated to good accuracy.

[0043] In general, during operation, when the battery device passes a given nthcorrection point (n being an integer value), the state of charge value Qnat said instant tncan be calculated according to the known state of charge correlation to the predetermined operational variable of the battery device. From this value, the ntherror current value lerr.n can be estimated and used to estimate the corrected current value Icorr.n and for the determination of the actual state of charge value, as described above. When the battery device reaches an (n+1)thcorrection point (which can be of the same type or a different type with respect to the nth correction point), the state of charge value Qn+i at said instant tn+i is determined, also according to the known state of charge correlation to the predetermined operational variable of the battery device.

[0044] If the corrected current Icorr.n was perfectly correct, the integral of lcorr,n(t) over the time interval between tnand tn+i should be equal to the difference in the state of charge values determined at tnand tn+i .

[0045] Under realistic conditions, however, there will still remain a deviation between the integrated corrected current and the difference in the state of charge values, and this deviation can be used to determine or estimate a new (subsequent) error current value lerr,n+i , to be used for the determination or estimation of the corrected current for time after the (n+1)thcorrection point. BASF SE 240115

[0046] Preferably, a respective value of the weighing factor W is associated to a respective charge correction range. Thus, for different charge correction points or ranges, different weighing factors can be used.

[0047] In an embodiment, a first charge correction range that has a higher precision in its relation between the respective operational variable of the battery device and the estimated state of charge value is associated to a greater weighing factor than a second charge correction range that has a lower precision in its relation between the respective operational variable of the battery device and the estimated state of charge value.

[0048] For instance, when the weighing factor is equal to 1 , the estimated error for the subsequent instant is fully updated by the error correction term. If, however, a smaller value (e.g., 0.5) is selected forthe weighing factor, only a fraction of the remaining deviation is added to the error current value lerr,k+i for the subsequent instant. If the weighing factor is selected to be zero, there is no update of the error current value. A strong amplification (e.g., values close to 1) can create a relatively jumpy profile in a state of charge vs. time plot or profile, at the instants where the state of charge values are estimated (e.g. at the charge correction points or ranges), while a moderate weighing factor results in smoother profiles but also slower mitigation of the errors. Values above 1 can also be selected for the weighing factor, however, this may lead to instabilities and strongly fluctuating error estimates.

[0049] Thus, the weighing factor can be different for each type of charge correction point or range, depending, for instance, on whetherthe estimated state of charge value at the given charge correction point is considered to be precise or not. Preferably, higher values of the weighing factor are used for charge correction points or ranges with precise state of charge estimation, and lower values of the weighing factor are used at charge correction points or ranges with less precise state of charge estimation.

[0050] In alternative embodiments, other update equations can be used, following the known principles of control engineering. For instance, the equation for updating the estimated error in the current may apply more elaborate control concepts, such as Kalman filtering or other, to attain a robust, effective adaptation of the estimated to the true error.

[0051] The method of the first aspect is based on an estimation of the error of the measured current provided to, or by, the battery device and the use of said estimation to correct the value of the current measured during ongoing operation of the battery device, rather than using BASF SE 240115 an incorrect measured current for operation control. Furthermore, the method reduces abrupt corrections of the state of charge value of the battery and delivers a smoother profile of the state of charge. Both the corrected current and the smooth state of charge profile are important elements in battery control systems, where they are used for safety relevant control (e.g., detection of end of charging / discharging) and for optimal battery operation (e.g., thermal managing, daily scheduling).

[0052] The use of faulty values of current or inconsistent (e.g., non-smooth) state of charge profiles for control purposes may lead to operation in unsuitable or even forbidden state of charge regions, to low utilization of the available battery capacity orto unreliable forecast in optimal daily scheduling, to name a few. Such sub-optimal operation reduces the profitability and the life-time of the battery. The method of the first aspect of the inventions enables the avoidance of such disadvantageous operating behavior.

[0053] A second aspect of the present invention is formed by a state of charge determination device for determining an actual state of charge value of a battery device and for monitoring and / or controlling said battery device. The state of charge determination device comprises a current value receiving unit that is configured to receive, or otherwise ascertain or acquire, a current value indicative of an electric current provided to, or by, the battery device as a function of time.

[0054] The state of charge determination device may also include a charge value determining unit that is configured to ascertain, or otherwise determine, a first state of charge value of the battery device at a first instant.

[0055] The state of charge determination device may also comprise an error current value determining unit that is configured to ascertain, or otherwise determine an error current value indicative of a deviation between a real current value and the received current value.

[0056] The state of charge determination device further comprises a corrected current value determination unit that is configured to calculate, or otherwise determine, a corrected current value using the received current value and the determined estimated error current value.

[0057] The state of charge determination device also includes an actual state of charge determination unit that is configured to determine the actual state of charge value of the battery device using the corrected current value and the first state of charge value and an actual BASF SE 240115 state of charge providing interface configured to provide the actual state of charge value for monitoring and / or controlling the battery device.

[0058] The state of charge determination device of the second aspect of the present invention thus shares the advantages of the method for determining an actual state of charge value of a battery device of the first aspect of the invention.

[0059] In the following, embodiments of the state of charge determination device of the second aspect will be disclosed.

[0060] Preferably, in an embodiment, the charge value determining unit is further configured to ascertain, or otherwise determine, a subsequent state of charge value of the battery device at a subsequent instant. In this particular embodiment, the state of charge determination device further comprises a correction term determination unit that is configured to calculate, or otherwise determine, an error correction term that is proportional to a difference of an integrated corrected current value provided to, or by, the battery device between the first instant and the subsequent instant and a difference between the first state of charge value and the subsequent state of charge value.

[0061] In this embodiment, the state of charge determination device also comprises a subsequent error determination unit that is configured to estimate, or otherwise determine, a subsequent error current value using the error current value and the calculated error correction term.

[0062] The corrected current value determination unit is then further configured to calculate, or otherwise determine, a subsequent corrected current value using the received current value and the determined subsequent error current value, and the actual state of charge value determination unit is further configured to determine the actual state of charge value of the battery device using the subsequent corrected current value and the subsequent state of charge value.

[0063] Preferably, in an embodiment, the charge value determining unit is configured to ascertain, or otherwise determine, the first state of charge value, and, optionally, the subsequent state of charge value or a plurality of subsequent state of charge values, when the battery device is operating at predetermined charge correction ranges, in which the state of charge value of the battery device is correlatable to a value of a predetermined operational variable of the battery device. BASF SE 240115

[0064] The state of charge determination device can be implemented as a dedicated device or integrated in a computer system. The different units described above can correspond to different hardware units, or software units. One or more of the units described above can be integrated into a common hardware unit or software unit.

[0065] A third aspect of the present invention is formed by a battery assembly. The battery assembly comprises a state of charge determination device in accordance with the second aspect of the invention. The battery assembly further comprises a battery device that is configured to provide or receive electric current and that has an actual state of charge value that depends on the amount of current provided and / or received. The battery assembly also comprises a current sensor that is configured to determine an electric current amount being provided or received and to provide a sensor signal indicative thereof, namely indicative of the current value.

[0066] Since the value of the electric current provided by the sensor signal can be faulty or otherwise deviate from the real current provided to, or by, the battery device, the use of the state of charge determination device enables the provision of a more accurate actual state of charge value of the battery device that is suitable to improve the monitoring and / or controlling of the battery device.

[0067] The battery assembly thus shares the advantages of the method of the first aspect and / or of the state of charge determination device of the second aspect.

[0068] In a preferred, but not limiting embodiment, the battery device is a sodium-sulphur battery device.

[0069] A sodium-sulphur (NaS) battery is a type of molten-salt battery that uses liquid sodium and liquid sulfur electrodes. This type of battery device is primarily used for stationary energy storage applications. Commercially available cells are typically large with high Coulomb capacities (up to 800Ah).

[0070] However, other embodiments of battery assemblies can include battery devices in accordance to alternative technologies, including lithium-ion batteries. BASF SE 240115

[0071] Preferably, in the case of a battery assembly with a NaS battery device, the predetermined charge correction ranges, in which the state of charge value of the battery device is correlatable to a value of a first predetermined operational variable of the battery device including:

[0072] - a first charge correction range at deep discharge states, wherein a value of an open cell voltage, as a first operational variable, is correlatable to a first state of charge value; and

[0073] - a second charge correction range at deep charge states, wherein a second state of charge value is correlated to an occurrence of a sharp increase in a battery resistance value, as a value of a second predetermined operational variable of the battery device.

[0074] In sodium-sulphur (NaS) batteries, two types of charge correction points are available. A first charge correction point is reached after a deep discharge, where the open cell voltage (i.e., at zero or negligible current) depends on the true state of charge in a correlatable manner. The second correction point is at the end of a deep charge phase; as the cell approaches a fully charged state, the value of the resistance increases sharply before the full charged state is reached. From experiments, it is known at which state of charge value this sharp increase in the value of the resistance occurs, so by applying an empirical correlation, the true state of charge value can be estimated with high accuracy.

[0075] In lithium-based batteries, the operating voltage continuously decreases during discharge operation. Once the state of charge value reaches a certain low value, the voltage starts to decrease more rapidly. Thus, the charge of state value at which the rapid decrease in the voltage occurs, can be used as a charge correction point for these batteries.

[0076] A fourth aspect of the present invention is formed by a computer program comprising instructions, which, when executed by a state of charge determination device, in particular according to the second aspect of the invention, cause the state of charge determination device to carry out the method of the first aspect of the invention.

[0077] It shall be understood that the methods described above, the devices described above and the computer program product described above have similar and / or identical preferred embodiments, in particular, as defined in the dependent claims. BASF SE 240115

[0078] It shall be understood that a preferred embodiment of the present invention can also be any combination of the dependent claim or above embodiments with a respective independent claim.

[0079] These and other aspects of the present invention will be apparent from and elucidated with reference to the embodiments described hereafter.

[0080] BRIEF DESCRIPTION OF THE DRAWINGS

[0081] In the following drawings:

[0082] Fig. 1 shows a schematic block diagram of an exemplary embodiment of a battery assembly according to the invention;

[0083] Fig. 2 shows a schematic block diagram of another exemplary embodiment of a battery assembly according to the invention;

[0084] Fig. 3 shows a flow diagram of an exemplary embodiment of a method for determining a state of charge value of a battery device according to the invention and controlling and / or monitoring said battery device; and

[0085] Fig. 4 shows a flow diagram of another exemplary embodiment of a method for determining a state of charge value of a battery device for controlling and / or monitoring said battery device according to the invention.

[0086] DETAILED DESCRIPTION OF EMBODIMENTS

[0087] Figure 1 shows a schematic block diagram of an exemplary battery assembly 200 according to the invention. The battery assembly 200 comprises a battery device 202 that is configured to provide or receive electric current lreai(t) and having an actual state of charge value Qc that depends on the amount of current lreai(t) provided and / or received. When the battery device 202 is connected to a power consumer 201 , the battery device 202 provides electric current to the power consumer 201 and the state of charge value decreases. It is assumed that this current has a first sign, in particular it is negative. When the battery device 202 is connected to a grid 203, the battery device 202 receives electric current from the power generator 203 and the state of charge value increases. This current has a second sign opposite to the first sign, in particular positive. BASF SE 240115

[0088] The battery assembly 200 comprises a current sensor 204 that is configured to determine an electric current amount being provided to, or received by, the battery device 202. The current sensor is configured to provide a sensor signal l(t) indicative thereof. The value of the current provided or received typically deviates from the real value of the current lreai(t) provided to, or received by, the battery device 202. These deviations accumulate overtime, possibly leading to unphysical computed values of the state of charge if not corrected.

[0089] The battery assembly 200 also comprises a state of charge determination device 100 in accordance with the invention. The state of charge determination device 100 is advantageously configured to accurately determine an actual state of charge value Qc Ofthe battery device 202. The state of charge determination device 100 comprises a current value receiving unit 102 that is configured to receive, or otherwise ascertain, the current value l(t) indicative of an electric current lreai(t) provided to, or by, the battery device 202 as a function of time. The value l(t) is indicative of the real current up to an error current, which is the a priori unknown difference between the real current value and the measured current value. Since typically the current is integrated over a given time span to determine the change in the state of charge during that time span, a small error in the current might have a high impact in the determined state of charge value, especially for long time spans.

[0090] The state of charge determination device 100 also includes a charge value determining unit 104 that is configured to ascertain, or otherwise determine, state of charge values Q of the battery device 202 at respective instants t. For example, it ascertains the state of charge value Qk at an instant tk. The ascertainment can be based on data provided by the sensor 204 and / or by the battery device 202 or other sensors associated to it.

[0091] Further, an error current value determining unit 106 is configured to ascertain, or otherwise determine, an error current value lerr.k indicative of a deviation between a real current value Ireai and the received current value l(t) and a corrected current value determination unit 108 is configured to calculate, or otherwise determine, a corrected current value lcorr,k(t) using the received current value l(t) and the determined error current value lerr.k. The error current value can be determined or estimated in different ways, e.g., by analyzing the current sensor, inferred from manufacturer’s specifications, or by comparison with other similar sensors, for example by determining a statistical average value using a plurality of sensors and determining a deviation of the respective determined values from the statistical average value. The corrected current value lCorr,k(t) can be expressed as:

[0092] Icorr,k ) ^(0 ^err,k BASF SE 240115

[0093] Further, an actual state of charge determination unit 110 is provided, which is configured to determine the actual state of charge value of the battery device using the corrected current value lcorr,k(t) and the first state of charge value Qk. For instance, the actual state of charge value Qccan be determined as:

[0094] The actual state of charge value is then provided via a suitable actual state of charge providing interface 112 configured to provide the actual state of charge for monitoring and / or controlling the battery device.

[0095] Figure 2 shows a schematic block diagram of another exemplary embodiment of a battery assembly 200 according to the invention. The following discussion will be focused on the differences between the battery assembly 200 of Figure 1 and the battery assembly 200 of Figure 2. Those technical features having an identical or similar functionality will be referred to using the same reference signs or numbers.

[0096] In the state of charge determination device 100 of Figure 2, the charge value determining 104 unit is further configured to ascertain, or otherwise determine, a plurality of state of charge values at respective instants. For example, in addition to the first state of charge value Qk determined at instant tk, a subsequent state of charge value Qk+i of the battery device is also determined at a corresponding subsequent instant tk+i .

[0097] The state of charge determination device 100 of Figure 2 further comprises a correction term determination unit 105 that is configured to calculate, or otherwise determine, an error correction term CT that is proportional to a difference of an integrated corrected current value lcorr,k(t) provided to, or by, the battery device between the first instant tk and the subsequent instant tk+i and a difference between the first state of charge value Qk and the subsequent state of charge value Qk+i. The correction term CT, can be determined as: wherein C is a proportionality factor. BASF SE 240115

[0098] A subsequent error determination unit 107 is also provided, which is configured to estimate, or otherwise determine, a subsequent error current value lerr,k+i using the error current value lerr.k and the calculated error correction term CT. For example, the subsequent error current value can be calculated as:

[0099] The equation for updating the subsequent error current value may apply more elaborated control concepts, such as Kalman filtering or other concepts, in order to attain a robust and effective adaptation of the estimation.

[0100] In the state of charge determination device 100 of Figure 2, the corrected current value determination unit 108 is further configured to calculate, or otherwise determine, a subsequent corrected current value Icorr, k+i(t) using the received current value l(t) and the determined subsequent error current value lerr,k+i. The subsequent corrected current value Icorr, k+ 1 (t) can be estimated as:

[0101] ^corr,fc+ l (f) f (f) fgrr.fc+1

[0102] Also, the actual state of charge value determination unit 110 shown in Fig. 2 is further configured to determine the actual state of charge value Qcof the battery device 202 using the subsequent corrected current value Icorr, k+i(t) and the subsequent state of charge value Qk+i. As an example, the actual value of the state of charge of the battery device 202 at an instant tcposterior to tk+i can be expressed as:

[0103] Preferably, the charge value determining unit 104 is configured to determine the first state of charge value QK and the subsequent state of charge values QK+I , when the battery device 202 is operating at predetermined charge correction ranges, in which the state of charge value of the battery device is correlatable to a value of a predetermined operational variable of the battery device.

[0104] Whenever the battery device is operated at a charge correction point or charge correction range, a new value of the state of charge is estimated, or otherwise determined, and used BASF SE 240115 to update the corresponding subsequent error current value, which is then used to determine the subsequent corrected current value that is used to determine the actual state of charge value at an instant posterior to the instant when the latest state of charge value was estimated (at a charge correction point). In this recursive approach, the initial error current value len-.o can be set to zero, and the first subsequent error current value lerr.i can be determined as: wherein Qo is the state of charge value determined at to (at a given charge correction point) and Qi is the state of charge value determined at ti (at a corresponding charge correction point) and C1 is a proportionality factor. Here, the measured current l(t) is directly used to infer the error correction value lerr. i , which is then used to estimate the subsequent corrected current value Icorr, nt), fortimes afterthe ti and before a subsequent charge correction point is reached.

[0105] The actual state of charge value Qcfor an instant tcafter ti can be expressed as:

[0106] When the battery device 202 reaches another charge correction point at an instant t2, a new state of charge value Q2 is estimated, and based thereon, a new subsequent -second- error current value lerr,2 can be estimated using the first corrected current value Icorr, i(t), as:

[0107] The value of the proportionality factor C2 can be the same as the value of the proportionality factor C1 , or can have a different value. Preferably the proportionality factors C1 , C2 used in the step of calculating or determining the error correction term is given by a weighing factor W divided by a time interval.

[0108] The time interval can correspond to the full interval between the first instant to and the subsequent instant ti. The same applies to further subsequent instants t2, to, etc., wherein the time interval can be defined as the difference between two consecutive instants tn-tn-i . BASF SE 240115

[0109] However, it is preferred that the time interval At corresponds to an active time span between an instant (e.g., tn) and subsequent instant relative to said instant (e.g., tn+i), during which the received current value (l(t)) deviates from zero by at least a predetermined current threshold value.

[0110] The time span between two consecutive instants tnand tn+i may include active operation time of the battery device (charge and discharge), but it may also include idle phases, during which no current is flowing. Preferably, the current is set to zero during these idle phases regardless of the actually measured current, which can be different from zero. In these cases, preferably only the active time of the time span is taken into account for the determination of the time interval, which can be referred to as active time interval. For instance, the active time interval Atactive.k is obtained by integrating the following equation: where Ithreshoid die is the predetermined current threshold value.

[0111] Regarding the weighing factor, it is preferred that a respective value of the weighing factor W is associated to a respective charge correction range. Thus, for different charge correction points or ranges, different weighing factors can be used. Thus, the weighing factor can be different for each type of charge correction point or range, depending, for instance, on whether the estimated state of charge value at the given charge correction point is considered to be precise or not. Preferably, higher values of the weighing factor are used for charge correction points or ranges with precise state of charge estimation, and lower values of the weighing factor are used at charge correction points or ranges with less precise state of charge estimation.

[0112] As a non-limiting example, the battery device 202 of Fig. 1 and 2 is a sodium-sulphur battery device, and the predetermined charge correction ranges, in which the state of charge value of the battery device is correlatable to a value of a first predetermined operational variable of the battery device including:

[0113] - a first charge correction range at deep discharge states, wherein a value of an open cell voltage, as a first operational variable, is correlatable to a first state of charge value; and BASF SE 240115

[0114] - a second charge correction range at deep charge states, wherein a second state of charge value is correlated to an occurrence of a sharp increase in a battery resistance value, as a value of a second predetermined operational variable of the battery device.

[0115] Fig. 3 shows a flow diagram of an exemplary embodiment of a method 300 for determining a state of charge value of a battery device for monitoring and / or controlling said battery device according to the invention that can be for instance carried out by the state of charge determination device 100 of Fig. 1 . The reader is thus also referred to the discussion of the state of charge determination device 100 of Fig 1 for more details. The method 300 of Fig. 3 comprises, in step 302, receiving a current value l(t) indicative of an electric current provided to, or by, the battery device 202 as a function of time. The method also comprises determining (e.g., estimating), in a step 304, a first state of charge value Qk of the battery device at a first instant tk. The method further comprises determining (e.g., estimating), in a step 306, an error current value lerr.k indicative of a deviation between a real current value Ireai and the received current value l(t). The method also includes, in a step 308, determining (e.g., calculating) a corrected current value lcorr,k(t) using the received current value l(t) and the determined error current value lerr.k and, in a step 310, determining the actual state of charge value Qcof the battery device using the corrected current value lCorr(t) and the first state of charge value Qk. The method also comprises, in a step 312, providing the actual state of charge value for monitoring and / or controlling the battery device.

[0116] Fig. 4 shows a flow diagram of another exemplary embodiment of a method 300 for determining a state of charge value of a battery device for monitoring and / or controlling said battery device according to the invention, which can be for instance carried out by the state of charge determination device 100 of Fig. 2. In the following, only the differences between the method 300 of Fig. 3 and the method 300 of Fig. 4 will be discussed in detail. The reader is also referred to the discussion of the method 300 of Fig. 3 and the discussion of the state of charge determination device 100 of Fig. 2.

[0117] With respect to the method 300 of Fig. 4, the method includes, in a step 304b, further determining (e.g., estimating) one or more subsequent state of charge values (e.g., Qk+i) of the battery device 202 at respective subsequent instants (e.g., tk+i). The method also includes, in a step 309, determining (e.g., calculating) an error correction term CT that is proportional to a difference of an integrated corrected current value lCOrr,k(t) provided to, or by, the battery device between the first instant tk and the subsequent instant tk+i and a difference between the first state of charge value Qk and the subsequent state of charge value Qk+i. The method includes, in a step 306b, determining (e.g., estimating) a subsequent error current value lerr,k+i using the error current value lerr.k and the calculated error BASF SE 240115 correction term CT. Then, in step 308b, a subsequent corrected current value lcorr,k+i(t) is determined (e.g., calculated) using the received current value l(t) and the determined subsequent error current value lerr,k+i , and further, in step 310, the determination of the actual state of charge value Qcof the battery device is performed using the subsequent corrected current value lcorr,k+i(t) and the subsequent state of charge value Qk+i. In addition, the method includes, in a step 312, providing the actual state of charge value, for instance via a suitable interface 112, for monitoring and / or controlling the battery device.

[0118] When a subsequent state of charge value Qk+2 is estimated, e.g., because the battery device is operated at another charge correction point or range, a new subsequent error current lerr,k+2 is estimated that is used to determine (e.g., calculate) a new subsequent corrected value lcorr,k+2 that is in turn used to calculate the actual state of charge value until another charge correction point or range is reached.

[0119] In summary, the invention is directed to a method for determining an actual state of charge value of a battery device, which includes receiving a current value indicative of an electric current provided to, or by, the battery device as a function of time, determining a first state of charge value of the battery device at a first instant, determining an error current value indicative of a deviation between a real current value and the received current value, determining a corrected current value using the received current value and the determined error current value and determining the actual state of charge value of the battery device using the corrected current value and the first state of charge value with an improved accuracy.

[0120] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

[0121] For the processes and methods disclosed herein, the operations performed in the processes and methods may be implemented in differing order. Furthermore, the outlined operations are only provided as examples, and some of the operations may be optional, combined into fewer steps and operations, supplemented with further operations, or expanded into additional operations without detracting from the essence of the disclosed embodiments.

[0122] Procedures like the ascertaining determining or receiving current values, estimating or calculating state of charge values, and / or error current values and / or corrected current values, BASF SE 240115 etc. performed by one or several units or devices can be performed by any other number of units or devices. These procedures can be implemented as program code means of a computer program and / or as dedicated hardware.

[0123] A computer program product may be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0124] Any units described herein may be processing units that are part of a classical computing system. Processing units may include a general-purpose processor and may also include a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or any other specialized circuit. Any memory may be a physical system memory, which may be volatile, non-volatile, or some combination of the two. The term “memory” may include any computer-readable storage media such as a non-volatile mass storage. If the computing system is distributed, the processing and / or memory capability may be distributed as well. The computing system may include multiple structures as “executable components”. The term “executable component” is a structure well understood in the field of computing as being a structure that can be software, hardware, or a combination thereof. For instance, when implemented in software, one of ordinary skill in the art would understand that the structure of an executable component may include software objects, routines, methods, and so forth, that may be executed on the computing system. This may include both an executable component in the heap of a computing system, or on computer- readable storage media. The structure of the executable component may exist on a computer-readable medium such that, when interpreted by one or more processors of a computing system, e.g., by a processor thread, the computing system is caused to perform a function. Such structure may be computer readable directly by the processors, for instance, as is the case if the executable component were binary, or it may be structured to be interpretable and / or compiled, for instance, whether in a single stage or in multiple stages, so as to generate such binary that is directly interpretable by the processors. In other instances, structures may be hard coded or hard wired logic gates, that are implemented exclusively or near-exclusively in hardware, such as within a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or any other specialized circuit. Accordingly, the term “executable component” is a term for a structure that is well understood by those of ordinary skill in the art of computing, whether implemented in software, hardware, or a combination. Any embodiments herein are described with reference to acts that are performed by one or more processing units of the computing system. If such acts are implemented in software, one or more processors direct the operation of the computing BASF SE 240115 system in response to having executed computer-executable instructions that constitute an executable component. Computing system may also contain communication channels that allow the computing system to communicate with other computing systems over, for example, network. A “network” is defined as one or more data links that enable the transport of electronic data between computing systems and / or modules and / or other electronic devices. When information is transferred or provided over a network or another communications connection, for ex-ample, either hardwired, wireless, or a combination of hardwired or wireless, to a computing system, the computing system properly views the connection as a transmission medium. Transmission media can include a network and / or data links which can be used to carry desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general-purpose or special-purpose computing system or combinations. While not all computing systems require a user interface, in some embodiments, the computing system includes a user interface system for use in interfacing with a user. User interfaces act as input or output mechanism to users for instance via displays.

[0125] Those skilled in the art will appreciate that at least parts of the invention may be practiced in network computing environments with many types of computing system configurations, including, personal computers, desktop computers, laptop computers, message processors, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile telephones, PDAs, pagers, routers, switches, datacenters, wearables, such as glasses, and the like. The invention may also be practiced in distributed system environments where local and remote computing system, which are linked, for example, either by hardwired data links, wireless data links, or by a combination of hardwired and wireless data links, through a network, both perform tasks. In a distributed system environment, program modules may be located in both local and remote memory storage devices.

[0126] Those skilled in the art will also appreciate that at least parts of the invention may be practiced in a cloud computing environment. Cloud computing environments may be distributed, although this is not required. When distributed, cloud computing environments may be distributed internationally within an organization and / or have components possessed across multiple organizations. In this description and the following claims, “cloud computing” is defined as a model for enabling on-demand network access to a shared pool of configurable computing resources, e.g., networks, servers, storage, applications, and services. The definition of “cloud computing” is not limited to any of the other numerous advantages that can be obtained from such a model when deployed. The computing systems of the figures | BASF SE | 240115 | 240115WQ01 ~ include various components or functional blocks that may implement the various embodiments disclosed herein as explained. The various components or functional blocks may be implemented on a local computing system or may be implemented on a distributed computing system that includes elements resident in the cloud or that implement aspects of cloud computing. The various components or functional blocks may be implemented as software, hardware, or a combination of software and hardware. The computing systems shown in the figures may include more or less than the components illustrated in the figures and some of the components may be combined as circumstances warrant.

[0127] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0128] A single unit or device may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0129] Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. BASF SE240115CLAIMS1 . Method (300) for monitoring and / or controlling a battery device (202), the method comprising:- receiving (302) a current value (l(t)) indicative of an electric current provided to, or by, the battery device as a function of time;- determining (304) a first state of charge value (Qk) of the battery device at a first instant (tk);- determining (306), an error current value (lerr.k) indicative of a deviation between a real current value (Ireai) and the received current value (l(t));- determining (308) a corrected current value (lcorr,k(t)) using the determined current value (l(t)) and the determined error current value (lerr.k); and- determining (310) the actual state of charge value (Qc) of the battery device using the corrected current value (lcorr(t)) and the first state of charge value (Qk);- providing (312) the actual state of charge value for monitoring and / or controlling the battery device.

2. The method of claim 1 , wherein the actual state of charge value (Qc) of the battery device is determined as the sum of the first state of charge value (Qk) and an integrated corrected current value provided to, or by, the battery device between the first instant (tk) and an actual instant (tc).

3. The method of claim 1 or 2, further comprising:- determining (304b) a subsequent state of charge value (Qk+i) of the battery device (202) at a subsequent instant (tk+i);- determining (309) an error correction term (CT) that is proportional to a difference of an integrated corrected current value (lcorr,k(t)) provided to, or by, the battery device between the first instant (tk) and the subsequent instant (tk+i) and a difference between the first state of charge value (Qk) and the subsequent state of charge value (Qk+i);BASF SE240115- determining (306b) a subsequent error current value (lerr,k+i) using the error current value (len-.k) and the calculated error correction term (CT);- determining (308b) a subsequent corrected current value (lcorr,k+i(t)) using the received current value (l(t)) and the determined subsequent error current value (lerr,k+i) ; and wherein- the determination (310) of the actual state of charge value (Qc) of the battery device is performed using the subsequent corrected current value (lcorr,k+i(t)) and the subsequent state of charge value (Qk+i).

4. The method of claim 3, wherein in the step of determining (309) the error correction term (CT) a proportionality factor is given by a weighing factor (W) divided by a time interval (At).

5. The method of claim 4, wherein the subsequent error current value (lerr, k+i) is determined as the sum of the error current value and the error correction term.

6. The method of claim 4 or 5, wherein the time interval (At) corresponds to an active time span between the first instant (tk) and the subsequent instant (tk+i), during which the received current value (l(t)) deviates from zero by at least a predetermined current threshold value.

7. The method of any of the preceding claims, wherein the determination of the first state of charge value (QK) and, optionally, of the subsequent state of charge value (QK+I), is performed when the battery device is operating at predetermined charge correction ranges, in which the state of charge value of the battery device is correlatable to a value of a predetermined operational variable of the battery device.

8. The method of any of the preceding claims 4 to 6, and 7, wherein a respective value of the weighing factor W is associated to a respective charge correction range.

9. The method of claim 8, wherein a first charge correction range having a higher precision in its relation between the respective operational variable of the battery device and the determined state of charge value is associated to a greater weighing factor than a second charge correction range having a lower precision in its relation between the respective operational variable of the battery device and the estimated state of charge value.BASF SE24011510. A state of charge determination device (100) for monitoring and / or controlling a battery device (202), the state of charge determination device comprising:- a current value receiving unit (102) configured to receive a current value (l(t)) indicative of an electric current (lreai(t)) provided to, or by, the battery device (200) as a function of time;- a charge value determining unit (104) configured to determine a first state of charge value (Qk) of the battery device (202) at a first instant (tk);- an error current value determining unit (106) configured to determine an error current value (lerr.k) indicative of a deviation between a real current value (Ireai) and the received current value (l(t));- a corrected current value determination unit (108)) configured to determine a corrected current value (lcorr,k(t)) using the received current value (l(t)) and the determined error current value (I err,k);- an actual state of charge determination unit (110) configured to determine the actual state of charge value of the battery device using the corrected current value (lcorr,k(t)) and the first state of charge value (Qk); and.- an actual state of charge providing interface (112) configured to provide the actual state of charge for monitoring and / or controlling the battery device.1 1 . The state of charge determination device of claim 10 wherein- the charge value determining unit (104) is further configured to determine a subsequent state of charge value (Qk+i) of the battery device at a subsequent instant (tk+i); wherein, the state of charge determination device further comprises:- a correction term determination unit (105) that is configured to determine an error correction term (CT) that is proportional to a difference of an integrated corrected current value (lcorr,k(t)) provided to, or by, the battery device between the first instant (tk) and the subsequent instant (tk+i) and a difference between the first state of charge value (Qk) and the subsequent state of charge value (Qk+i);BASF SE240115- a subsequent error determination unit (107) configured to determine a subsequent error current value (lerr,k+i) using the error current value (lerr.k) and the calculated error correction term (CT); wherein- the corrected current value determination unit (108) is further configured to determine a subsequent corrected current value (lcorr,k+i (t)) using the determined current value (l(t)) and the determined subsequent error current value (lerr,k+i); and- the actual state of charge value determination unit (110) is further configured to determine the actual state of charge value (Qc) of the battery device (202) using the subsequent corrected current value (lcorr,k+i(t)) and the subsequent state of charge value (Qk+i).

12. The state of charge determination (100) device of claim 10 or 11 , wherein- the charge value determining unit (104) is configured to determine the first state of charge value (QK) and, optionally, the subsequent state of charge value (QK+I), when the battery device (202) is operating at predetermined charge correction ranges, in which the state of charge value of the battery device is correlatable to a value of a predetermined operational variable of the battery device.

13. A battery assembly (200), comprising- a state of charge determination device (100) in accordance with any of the preceding claims 10 to 12;- a battery device (202) configured to provide or receive electric current lreai(t) and having an actual state of charge value (Qc) that depends on the amount of current provided and / or received; and- a current sensor (204) configured to determine an electric current value being provided or received and to provide a sensor signal (l(t)) indicative thereof.

14. The battery assembly (200) of claim 13, wherein the battery device is a sodiumsulphur battery device, and wherein, optionally, the predetermined charge correction ranges, in which the state of charge value of the battery device is correlatable to a value of a first predetermined operational variable of the battery device including| BASF SE | 240115 | 240115WQ01 ~- a first charge correction range at deep discharge states, wherein a value of an open cell voltage, as a first operational variable, is correlatable to a first state of charge value; and- a second charge correction range at deep charge states, wherein a second state of charge value is correlated to an occurrence of a sharp increase in a battery resistance value, as a value of a second predetermined operational variable of the battery device.

15. Computer program comprising instructions, which, when executed by a state of charge determination device, in particular according to any of the claims 10 to 12, cause the state of charge determination device to carry out the method of any of the claims 1 to 9.

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