Extrapolated battery state of charge determination and utilization

Abstract

A battery system includes a multi-cell rechargeable energy storage system (RESS) and an electronic controller configured to process RESS cell data. The controller is programmed with a battery cell open circuit voltage (OCV) versus state of charge (SOC) data table used to calculate a peak OCV shift for a representative battery cell at a predetermined capacity and maximum discharge / charge rate, the controller configured to acquire voltage data for one of the cells during an active RESS cycle. The controller is further configured to pass the acquired voltage data through a first order lag filter algorithm to generate an over-predicted OCV for the subject cell of interest. The controller is additionally configured to determine an over-predicted SOC value in the data table for the subject cell of interest using an OCV value from the over-predicted OCV. Further, the controller is configured to regulate the RESS using the over-predicted SOC value determined for the subject cell of interest.

Description

Technical Field

[0001] introduction

[0002] This disclosure generally relates to the determination of over-predicted battery state of charge and its utilization for battery diagnostics and remedial measures. Background Technology

[0003] Energy storage, battery systems, or arrays may include multiple battery cells arranged relatively close to each other. Multiple battery cells can be assembled into battery stacks or modules, and multiple battery modules can be assembled into battery packs. In large battery packs, individual packs may also be divided into independent battery sub-packs, each of which includes an array of battery modules. Batteries can be broadly classified into primary batteries and secondary batteries.

[0004] Primary batteries (also known as disposable batteries) are designed to be used until their charge is depleted, after which they are simply replaced with new batteries. Secondary batteries (more commonly known as rechargeable batteries) use specific high-energy chemistry, allowing them to be repeatedly recharged and reused, thus offering economic, environmental, and ease-of-use benefits compared to primary batteries. Rechargeable batteries can be used to power objects such as toys, consumer electronics, and rotating motors (such as electric motors-generators or traction motors used in electrically propelled vehicles). The battery cells can actively deplete their charge through self-discharge during operation of the powered object or during storage.

[0005] In electric vehicle powertrains employing the aforementioned rotating motor, energy is drawn from the battery cells whenever the electric powertrain operates in drive or propulsion mode; that is, the battery cells actively discharge. Depending on the specific configuration of the motor, the battery cells can be recharged via an external charging station and / or via on-board regeneration. Cell data (such as individual cell or cell group voltages, charging and discharging currents to and from battery cells or cell groups, and temperature measurements sampled at various locations within the battery system) are collected by the battery control unit and closely monitored over time. This cell data is used to determine the battery's state of charge (SOC) and overall health.

[0006] State of Charge (SOC) is typically the charge level of an electric battery relative to its capacity. SOC is measured in percentage points (0% = empty; 100% = fully charged). An alternative form of the same metric is Depth of Discharge (DOD), which is the reciprocal of SOC (100% = empty; 0% = fully charged). SOC is generally used when discussing the state of current of a battery in use, while DOD is most commonly used when discussing the battery's lifespan after repeated use. Battery control units are typically configured to monitor battery operation and adjust battery control parameters based on collected cell data and determined parameters such as SOC or DOD. Summary of the Invention

[0007] A battery system includes: a multi-cell rechargeable energy storage system (RESS) having a plurality of battery cells; and an electronic controller connected to the RESS and configured to process data from the plurality of battery cells. The electronic controller is programmed to have a battery cell open-circuit voltage (OCV) versus state-of-charge (SOC) data table. The OCV versus SOC data table is used to calculate the peak OCV movement of a representative battery cell at a predetermined or rated capacity and maximum discharge or charge rate. The electronic controller is configured to acquire real-time voltage data for one of the plurality of battery cells during active cycling of the RESS.

[0008] The electronic controller is also configured to pass the acquired voltage data through a first-order hysteresis filter algorithm. The first-order hysteresis filter algorithm is configured to generate an over-predicted OCV for one of the plurality of battery cells, such that the over-predicted OCV is calibrated to progress slower during discharge and faster during charging than the calculated peak OCV change by a predetermined margin. The electronic controller is additionally configured to use the OCV value from the over-predicted OCV to determine (e.g., look up) an over-predicted SOC value for one of the plurality of battery cells in an OCV-to-SOC data table, wherein the over-predicted SOC value exceeds the predetermined margin of the true SOC of the subject battery cell. Furthermore, the electronic controller is configured to adjust the RESS using the over-predicted SOC value determined for one of the plurality of battery cells.

[0009] The predetermined margin can be controlled to be no more than 5% error relative to the actual SOC, which is the over-predicted SOC.

[0010] The first-order hysteresis filter algorithm may include a first filter gain coefficient, which is calibrated to generate an over-predicted OCV for one of the plurality of battery cells during active cycling of the RESS using voltage data acquired for one of the plurality of battery cells.

[0011] The electronic controller may be configured to acquire temperature data for one of the plurality of battery cells. The first-order hysteresis filter algorithm may include a second calibrated filter gain coefficient, which is determined as a function of the acquired temperature and voltage data for one of the plurality of battery cells, acquired by the controller.

[0012] The electronic controller can be configured to regulate the RSS by controlling the flow rate and / or temperature of the coolant through the RSS to remove heat energy from one of the plurality of battery cells when the over-predicted SOC value is within a predetermined margin.

[0013] The electronic controller can be configured to regulate the RESS by controlling the speed of the cooling fan to remove heat from one of the plurality of battery cells when the over-predicted SOC value is within a predetermined margin.

[0014] The electronic controller can be configured to adjust the RESS by controlling the charging and / or discharging rates of the plurality of battery cells when the over-predicted SOC value is within a predetermined margin.

[0015] Controlling the charging and / or discharging rate of the plurality of battery cells may include limiting the power output of a traction motor operatively connected to the RESS, or limiting the charging current of an on-board charging station or an off-board charging station for plug-in charging.

[0016] A method for regulating a multi-cell rechargeable energy storage system (RESS) with multiple battery cells as described above is also disclosed, as well as a motor vehicle employing a traction motor and an RESS connected to an electronic controller.

[0017] The present invention also provides the following technical solutions:

[0018] 1. A battery system comprising:

[0019] Multi-cell rechargeable energy storage system (RESS) having multiple battery cells; and

[0020] An electronic controller, which is connected to the RESS and configured to process data from the plurality of battery cells;

[0021] in:

[0022] The electronic controller is programmed to have a battery cell open-circuit voltage (OCV) versus state of charge (SOC) data table;

[0023] The OCV-to-SOC data table is used to calculate the peak OCV change of a representative battery cell at a predetermined capacity and maximum discharge or charge rate; and

[0024] The electronic controller is configured such that:

[0025] During the active cycling of the RESS, voltage data is acquired for one of the plurality of battery cells;

[0026] The acquired voltage data is passed through a first-order hysteresis filter algorithm to generate an over-predicted OCV for one of the plurality of battery cells, such that the over-predicted OCV is calibrated to progress slower during discharge and faster during charging than the calculated peak OCV change by a predetermined margin.

[0027] Using the OCV value from the over-predicted OCV, an over-predicted SOC value is determined for one of the plurality of battery cells in the OCV vs. SOC data table, wherein the over-predicted SOC value exceeds the predetermined margin of the true SOC of the one of the plurality of battery cells; and

[0028] The RESS is adjusted using the over-predicted SOC value determined for one of the plurality of battery cells.

[0029] 2. The battery system according to technical solution 1, wherein the predetermined margin is controlled to be no more than 5% error relative to the actual SOC of the over-predicted SOC.

[0030] 3. The battery system according to technical solution 1, wherein the first-order hysteresis filter algorithm includes a first filter gain coefficient, the first filter gain coefficient being calibrated to generate the over-predicted OCV for one of the plurality of battery cells using voltage data acquired for one of the plurality of battery cells during the active cycling of the RESS.

[0031] 4. The battery system according to technical solution 1, wherein the electronic controller is additionally configured to: acquire temperature data for one of the plurality of battery cells, the first-order hysteresis filter algorithm including a calibrated second filter gain coefficient, the calibrated second filter gain coefficient being determined as a function of the temperature and voltage data acquired for one of the plurality of battery cells.

[0032] 5. The battery system according to technical solution 1, wherein the electronic controller is configured to: adjust the RSS by controlling the flow rate and / or temperature of the coolant through the RSS to remove heat energy from one of the plurality of battery cells when the over-predicted SOC value is within a predetermined margin.

[0033] 6. The battery system according to technical solution 1, wherein the electronic controller is configured to: adjust the RESS by controlling the speed of a cooling fan to remove heat energy from one of the plurality of battery cells when the over-predicted SOC value is within a predetermined margin.

[0034] 7. The battery system according to technical solution 1, wherein the electronic controller is configured to adjust the RESS by controlling the charging and / or discharging rates of the plurality of battery cells when the over-predicted SOC value is within a predetermined margin.

[0035] 8. The battery system according to technical solution 7, wherein controlling the charging and / or discharging rate of the plurality of battery cells includes at least one of the following:

[0036] Limit the power output of the traction motor operatively connected to the RESS; and

[0037] Adjust the charging current of either the on-board charging station or the off-board charging station.

[0038] 9. A method for regulating a multi-cell rechargeable energy storage system (RESS) having multiple battery cells, the method comprising:

[0039] During the active cycling of the RESS, voltage data is acquired for one of the plurality of battery cells, wherein:

[0040] The electronic controller is programmed to have a battery cell open-circuit voltage (OCV) versus state of charge (SOC) data table;

[0041] The OCV-to-SOC data table is used to calculate the peak OCV change of a representative battery cell at a predetermined capacity and maximum discharge or charge rate.

[0042] The acquired voltage data is transmitted through the electronic controller via a first-order hysteresis filter algorithm to generate an over-predicted OCV for one of the plurality of battery cells, such that the over-predicted OCV is calibrated to progress slower during discharge and faster during charging than the calculated peak OCV change by a predetermined margin.

[0043] Via the electronic controller, using the OCV value from the over-predicted OCV, an over-predicted SOC value is determined for one of the plurality of battery cells in the OCV vs. SOC data table, wherein the over-predicted SOC value exceeds the predetermined margin of the true SOC of the one of the plurality of battery cells; and

[0044] The RESS is adjusted via the electronic controller using the over-predicted SOC value determined for one of the plurality of battery cells.

[0045] 10. The method according to technical solution 9, wherein the predetermined margin is controlled to be no more than 5% error relative to the actual SOC of the over-predicted SOC.

[0046] 11. The method according to technical solution 9, wherein transmitting the acquired voltage data through the first-order hysteresis filter algorithm comprises: calibrating the first filter gain coefficient to generate the over-predicted OCV for one of the plurality of battery cells using the voltage data acquired for one of the plurality of battery cells during the active cycling of the RESS.

[0047] 12. The method according to technical solution 9, further comprising: acquiring temperature data for one of the plurality of battery cells via the electronic controller, wherein the first-order hysteresis filter algorithm includes a calibrated second filter gain coefficient, the calibrated second filter gain coefficient being determined as a function of the temperature and voltage data acquired for one of the plurality of battery cells.

[0048] 13. The method according to technical solution 9, wherein adjusting the RESS is performed when the over-predicted SOC value is within a predetermined margin by at least one of the following: controlling the flow rate and / or temperature of the coolant through the RESS to remove heat energy from the one of the plurality of battery cells, controlling the speed of the cooling fan to remove heat energy from the one of the plurality of battery cells, and controlling the charging and / or discharging rate of the plurality of battery cells.

[0049] 14. The method according to technical solution 13, wherein controlling the charging and / or discharging rate of the plurality of battery cells includes at least one of the following:

[0050] Limit the power output of the traction motor operatively connected to the RESS; and

[0051] Adjust the charging current of either the on-board charging station or the off-board charging station.

[0052] 15. A motor vehicle comprising:

[0053] Multi-cell rechargeable energy storage system (RESS) has multiple battery cells;

[0054] A traction motor, operatively connected to the RESS; and

[0055] An electronic controller, which is connected to each of the RESS and the traction motor and is configured to process data from the plurality of battery cells;

[0056] in:

[0057] The electronic controller is programmed to have a battery cell open-circuit voltage (OCV) versus state of charge (SOC) data table;

[0058] The OCV-to-SOC data table is used to calculate the peak OCV change of a representative battery cell at a predetermined capacity and maximum discharge or charge rate; and

[0059] The electronic controller is configured such that:

[0060] During the active cycling of the RESS, voltage data is acquired for one of the plurality of battery cells;

[0061] The acquired voltage data is passed through a first-order hysteresis filter algorithm to generate an over-predicted OCV for one of the plurality of battery cells, such that the over-predicted OCV is calibrated to progress slower during discharge and faster during charging than the calculated peak OCV change by a predetermined margin.

[0062] Using the OCV value from the over-predicted OCV, an over-predicted SOC value is determined for one of the plurality of battery cells in the OCV vs. SOC data table, wherein the over-predicted SOC value exceeds the predetermined margin of the true SOC of the one of the plurality of battery cells; and

[0063] The RESS is adjusted using the over-predicted SOC value determined for one of the plurality of battery cells.

[0064] 16. The motor vehicle according to technical solution 15, wherein the predetermined margin is controlled to be no more than 5% error relative to the actual SOC of the over-predicted SOC.

[0065] 17. The motor vehicle according to claim 15, wherein the first-order hysteresis filter algorithm includes a first filter gain coefficient, the first filter gain coefficient being calibrated to generate the over-predicted OCV for one of the plurality of battery cells during the active cycling of the RESS, the over-predicted OCV tracking voltage data acquired for one of the plurality of battery cells within the predetermined margin.

[0066] 18. The motor vehicle according to claim 15, wherein the electronic controller is additionally configured to acquire temperature data for one of the plurality of battery cells, the first-order hysteresis filter algorithm including a calibrated second filter gain coefficient, the calibrated second filter gain coefficient being determined as a function of the temperature and voltage data acquired for one of the plurality of battery cells.

[0067] 19. The motor vehicle according to claim 15, wherein the electronic controller is configured to adjust the RESS via at least one of the following when the over-predicted SOC value is within a predetermined margin: controlling the flow rate and / or temperature of the coolant through the RESS to remove heat energy from one of the plurality of battery cells, controlling the speed of a cooling fan to remove heat energy from one of the plurality of battery cells, and controlling the charging and / or discharging rate of the plurality of battery cells.

[0068] 20. The motor vehicle according to technical solution 19, wherein controlling the charging and / or discharging rate of the plurality of battery cells includes at least one of the following:

[0069] Limit the power output of the traction motor operatively connected to the RESS; and

[0070] Adjust the charging current of either the on-board charging station or the off-board charging station.

[0071] The above features and advantages, as well as other features and advantages, will readily become apparent from the following detailed description of the embodiments and preferred modes for carrying out the described disclosure, taken in conjunction with the accompanying drawings and claims. Attached Figure Description

[0072] Figure 1 This is a schematic top view of an embodiment of a motor vehicle according to the present disclosure, which employs a powertrain with multiple power sources and a multi-cell rechargeable energy storage system (RESS) configured to generate and store electrical energy for supplying such electrical energy to the power sources.

[0073] Figure 2The circuit diagram of the RESS battery cell connected to an electronic controller according to the present disclosure is provided. The electronic controller is configured to regulate the operation of the RESS.

[0074] Figure 3A It is a graph depicting the change in open-circuit voltage (OCV) over time of a representative battery cell according to this disclosure, compared with the state of charge (SOC) of the battery cell (showing a predetermined offset that progresses more slowly during discharge), and the change in OCV across the SOC as predicted by a calibrated first-order hysteresis filter.

[0075] Figure 3B It is a graph depicting the change in OCV over time of a representative battery cell according to this disclosure compared to the SOC of the battery cell (showing a predetermined offset that progresses faster during charging), and the change in OCV across the SOC as predicted by a calibrated first-order hysteresis filter.

[0076] Figure 4A This is a graph depicting an exemplary discharge profile of the over-predicted OCV from the output of a calibrated first-order hysteresis filter according to this disclosure, compared to the actual / ideal OCV.

[0077] Figure 4B It is a graph depicting the over-predicted SOC compared to the actual SOC, obtained from the OCV-SOC data table according to this disclosure.

[0078] Figure 5 The diagram illustrates the adjustment. Figure 1-2 The method of the multi-cell rechargeable energy storage system (RESS) shown in Figure 3-4 and the data processing of the battery cell OCV versus SOC described in Figure 3-4. Detailed Implementation

[0079] refer to Figure 1 The diagram depicts a motor vehicle 10 having a powertrain 12. The vehicle 10 may include, but is not limited to, commercial vehicles, industrial vehicles, passenger vehicles, aircraft, boats, trains, etc. It is also envisioned that the vehicle 10 may be a mobile platform, such as an aircraft, an all-terrain vehicle (ATV), a boat, a personal mobile device, a robot, etc., to achieve the purposes of this disclosure. The powertrain 12 includes a power source 14 configured to generate a power source torque T (in...). Figure 1 (As shown) for propelling the vehicle 10 via the driven wheel 16 relative to the road surface 18. The power source 14 is depicted as an electric traction motor-generator. Figure 1 As shown, the powertrain 12 may also include an additional power source 20, such as an internal combustion engine. Power sources 14 and 20 can work together to power the vehicle 10.

[0080] The vehicle 10 additionally includes a programmable electronic controller 22 and a multi-cell rechargeable energy storage system (RESS) 24. Figure 2 The general structure of RESS 24 is schematically shown in the figure. As shown, multiple battery cells 26 can initially be combined into cell packs 28, where the individual cells can be arranged in parallel. Cell packs 28 can then be organized into battery modules 30, where the individual cell packs are arranged in series (i.e., connected). Figure 2 A single module 30 is shown, but RESS 24 can have many such modules as needed. Multiple modules 30 can then be arranged in various battery sub-packs (not shown). The operation of the powertrain 12 and RESS 24 can generally be regulated by an electronic controller 22. RESS 24 can be connected via a high-voltage bus 33 (in... Figure 1 (As shown in the figure) It is operatively connected to power sources 14 and 20, electronic controller 22, and other vehicle systems.

[0081] RESS 24 is configured to generate and store electrical energy through an electrochemical reaction that produces heat, and is available in vehicle 10 for supplying this electrical energy via an electrical connection to power sources 14 and 20. Electronic controller 22 can be programmed to control powertrain 12 and RESS 24 to generate a predetermined amount of power source torque T, and to control various other vehicle systems. Electronic controller 22 may include a central processing unit (CPU) that regulates various functions on vehicle 10, or be configured as a powertrain control module (PCM) configured to control powertrain 12. In either of these configurations, electronic controller 22 includes a processor and a tangible, non-transitory memory containing instructions programmed therein for operating powertrain 12 and battery system 24. The memory may be a suitable recordable medium involved in providing computer-readable data or process instructions. Such a recordable medium may take many forms, including but not limited to non-volatile and volatile media.

[0082] Non-volatile media used for the electronic controller 22 may include, for example, optical discs or magnetic disks, and other persistent storage. Volatile media may include, for example, dynamic random access memory (DRAM), which may constitute the main memory. Instructions may be transmitted via one or more transmission media, including coaxial cables, copper wires, and optical fibers, or via a wireless connection, the transmission media including wires comprising a system bus connected to a computer processor. The memory of the electronic controller 22 may also include floppy disks, hard disks, magnetic tapes, another magnetic medium, CD-ROMs, DVDs, another optical medium, etc. The electronic controller 22 may be constructed or equipped with other necessary computer hardware, such as a high-speed clock, necessary analog-to-digital (A / D) and / or digital-to-analog (D / A) circuitry, input / output circuitry and devices (I / O), and appropriate signal conditioning and / or buffering circuitry. Algorithms required by or available to the electronic controller 22 may be stored in memory and executed automatically to provide the necessary functions for the powertrain 12 and RESS 24. The electronic controller 22 is also configured to monitor RESS 24 and process data from the plurality of battery cells 26 (e.g., via the algorithms discussed in this paper).

[0083] The electronic controller 22 is programmed to have a battery cell open-circuit voltage (OCV) versus state-of-charge (SOC) data table 34 (expressed as a percentage of maximum value). The OCV versus SOC data table 34 is used to calculate the peak OCV change 36 (shown in Figure 3, which depicts the voltage change versus the SOC of the battery cell) of a representative battery cell at a predetermined (e.g., rated) cell capacity and maximum discharge or charge rate, in V / sec. The OCV versus SOC data table 34 can be compiled empirically using one or more representative battery cells 26 to determine… Figure 3A and Figure 3B The voltage shown represents the change or amount of change over time. The electronic controller 22 is configured to access data table 34 along with one or more algorithms, which will be described in detail below, during the active cycle of the RESS 24 (e.g., when the RESS supplies electrical energy to various vehicle systems and / or receives charging current).

[0084] The electronic controller 22 is configured (i.e., programmed) to regulate the operation of the RESS 24 by acquiring real-time voltage data (e.g., via (a plurality of) voltage sensors (not shown)) for each of the battery cells 26 at multiple sampling points initially during the active cycle of the RESS. For illustrative purposes, the information regarding one of the battery cells 26 (identified as battery cell 26A) will be used. Figure 2The operation of the electronic controller 22 is described in the diagram. Specifically, the electronic controller 22 is configured to acquire real-time voltage data 38 for battery cell 26A during the active cycle of RESS 24. The electronic controller 22 is configured to then transmit the voltage data 38 acquired from battery cell 26A via a first-order hysteresis filter algorithm 40 programmed into the controller. Filtering the acquired voltage data 38 via the first-order hysteresis filter algorithm 40 aims to adjust the allowable OCV variation 42 during battery use (in...) Figure 3A and Figure 3B (as shown in the image) to generate over-predicted OCV 41 for battery cell 26A (in... Figure 4A (As shown in the figure). Since the voltage change of the battery cell is affected by temperature, the first-order hysteresis filter algorithm 40 is calibrated as a function of the temperature of the battery cell 26A to facilitate: mapping the voltage change across temperature to a more representative and smoother variation in the allowable OCV change 42 over time during battery use.

[0085] Battery cell capacity will change over time. Typically, the decrease in the change in OCV of a battery cell occurs at its maximum cell capacity. The capacity used to determine the peak OCV change 36 can be offset or reduced to over-predict the current SOC. Therefore, the allowable OCV change 42 during battery use is intended to over-predict the actual battery cell OCV change 43 (in the context of battery use) by using assumptions of higher battery cell capacity or slower current rate during discharge, or lower battery cell capacity or faster current rate during charging. Figure 4A (As shown in the figure). Assuming the battery cell discharges or charges at maximum current, the change in SOC per second of the battery cell can be expressed by the following expression:

[0086]

[0087] Therefore, the SOC data can be compared with OCV in Table 34 (in Figure 2 (As shown) The OCV change for a given battery cell capacity is calculated in 1% increments. Given the above, the first-order hysteresis filter algorithm 40 can be calibrated so that the maximum battery cell voltage (as the output of the OCV change 42) changes slower during discharge than or faster during charging than the calculated OCV change for the battery cell in question.

[0088] Specifically, the allowed OCV change 42 is calibrated via a first filter gain coefficient 40A of the selection filter algorithm 40 to progress slower during discharge and faster during charging than the calculated peak OCV change 36, in order to reduce SOC over-prediction by a predetermined margin 44. Specifically, the first filter gain coefficient 40A can be calibrated to generate an OCV for battery cell 26A during active cycling of RESS 24, compared to the actual or true SOC 46 of battery cell 26A (in... Figure 4B (As shown in the diagram) Over-predicted within a predetermined SOC margin 44. The predetermined margin 44 can be defined as the percentage (%) difference between the over-predicted SOC and the actual SOC. The predetermined margin 44 can be specifically calibrated to be no more than 5% overestimated relative to the actual SOC 46. The electronic controller 22 can be additionally configured to acquire temperature data 39 for the battery cell 26A (in... Figure 2 (As shown in the diagram), such as via a temperature sensor (not shown). Furthermore, the first-order hysteresis filter algorithm 40 may include a calibrated second filter gain coefficient 40B, which is determined as a function of the voltage data 38 and temperature data 39 acquired for the battery cell 26A. Therefore, the calibrated second filter gain coefficient 40B can be specifically used to establish a predetermined margin 44.

[0089] The electronic controller 22 is also configured to use the over-predicted OCV value from the battery cell 26A to determine or look up the corresponding over-predicted SOC value 48 in the SOC data table 34 (in Figure 4B (As shown in the image). The over-predicted SOC value of 48 exceeds the actual SOC of the battery cell (26A) of 46 (in the image). Figure 4B (As shown in the diagram) This predetermined margin 44. In the case of an over-predicted SOC value 48, the predetermined margin 44 will be based on the percentage of the battery's actual SOC 46. The predetermined margin 44 can be specifically controlled to not exceed 5% relative to the actual SOC 46. The electronic controller 22 is additionally configured to adjust the RESS 24 using the over-predicted SOC value 48 determined for the battery cell 26A via the operation of various vehicle 10 systems and accessories.

[0090] The electronic controller 22 may be specifically configured to control the flow rate and / or temperature of the coolant 50 through the RESS 24, such as by circulating the coolant through a coolant plate 52 arranged adjacent to the battery cell 26. Figure 2 (As shown in the diagram). Controlling the flow rate and / or temperature of the coolant 50 is intended to remove heat energy from the battery cell 26A when the over-predicted SOC value 48 is within a predetermined margin 44 or a preset lower limit. In addition to the above, the electronic controller 22 may also be configured to regulate the RESS 24 by controlling the cooling fan 56 (in the diagram). Figure 2 (As shown in the figure) to remove heat energy from battery cell 26A at a speed of (the speed shown in the figure).

[0091] The electronic controller 22 may also be configured to regulate the RESS 24 by controlling the charging and / or discharging rates of the plurality of battery cells 26. Specifically, the electronic controller 22 may regulate the discharge rate of battery cell 26A by limiting the power output of traction motor 14 or regulate the cell charging rate by adjusting the amount of regenerative braking of the traction motor. Additionally, when the over-predicted SOC value 48 is within a predetermined margin 44, the electronic controller 22 may regulate the discharge rate of battery cell 26A by limiting the charging current of on-board charging station 58 or off-board charging station 60 (e.g., in plug-in vehicle applications).

[0092] In summary, the over-predicted OCV 41 generated via the described filtering is intended to represent an over-predicted SOC that does not underestimate the true SOC of the battery cell 26. Therefore, the over-predicted OCV 41 enables earlier derating of the current draw in the RESS 24 and targets a lower operating temperature for the RESS 24. This measure mitigates the probability of the RESS 24 entering a thermal runaway event, in which a thermal event initiating within an individual cell can cause heat to spread uncontrollably to adjacent cells in the module and affect the entire battery array. Furthermore, the early remedial measures based on the over-predicted OCV 41 can prevent thermal events in specific battery cells that might otherwise be triggered by conditions such as intra-cell short circuits, improper cell use, physical abuse, manufacturing defects, or cell exposure to extreme external temperatures.

[0093] Method 100 for adjusting RESS 24 Figure 5 As shown in the figure and referenced below Figure 1 The structure shown in -4 is described. Method 100 begins in frame 102, where the operation of RESS 24 is monitored and current inflow or current consumption (e.g., from various vehicle systems and accessories in vehicle 10) is detected. Following frame 102, the method continues to frame 104. In frame 104, the method includes: during the active cycling of RESS 24, acquiring real-time voltage data 38 for each individual battery cell 26 (e.g., cell 26A) via electronic controller 22. As described above regarding... Figure 1 As described in section -4, the electronic controller 22 is programmed to have a battery cell OCV vs. SOC data table 34, wherein the subject data table is used to calculate the peak OCV change 36 of battery cell 26A at a predetermined capacity and maximum discharge or charge rate. Following frame 104, the method proceeds to frame 106.

[0094] In framework 106, the method includes: passing acquired voltage data 38 via an electronic controller 22 through a first-order hysteresis filter algorithm 40. Therefore, filtering the acquired voltage data 38 aims to generate an over-predicted OCV 41 for battery cell 26A, such that the over-predicted OCV is calibrated to progress slower during discharge and faster during charging than the actual OCV change 43. Passing the acquired voltage data 38 through the first-order hysteresis filter algorithm 40 includes calibrating a first filter gain coefficient 40A to generate the over-predicted OCV 41 for battery cell 26A. In framework 106, the method may additionally include: acquiring temperature data 39 for battery cell 26A via an electronic controller. The first-order hysteresis filter algorithm 40 may include a calibrated second filter gain coefficient 40B, which is determined as a function of the acquired voltage data 38 and temperature data 39 for battery cell 26A.

[0095] The method moves from frame 106 to frame 108, wherein the method includes: determining an over-predicted SOC value 48 for battery cell 26A in the OCV vs. SOC data table 34, using the OCV value from the over-predicted OCV 41, via electronic controller 22. As described above, the over-predicted SOC value 48 is intended to exceed the true SOC 46 of battery cell 26A by a predetermined margin 44. Specifically, the predetermined margin 44 may be controlled to not exceed 5% relative to the true SOC 46. After frame 108, the method proceeds to frame 110.

[0096] In frame 110, the method includes: adjusting RESS 24 via electronic controller 22 using remedial measures based on an over-predicted SOC value 48 determined for battery cell 26A. According to the method, adjusting RESS 24 may be accomplished by controlling at least one of the flow rate and / or temperature of coolant 50 through RESS 24 to remove heat energy from battery cell 26A. Adjusting RESS 24 may also include controlling the speed of cooling fan 56. Additionally, the method may include controlling the charging and / or discharging rate of battery cell 26A. As described above, controlling the charging and / or discharging rate of battery cell 26A may include limiting the power output of traction motor 14 or limiting the charging current of on-board charging station 58 or off-board charging station 60. Each of the measures listed above may be accomplished in response to the over-predicted SOC value 48 being assessed as being within a predetermined margin 44.

[0097] After either frame 108 or 110, the method can loop back to frame 104 to continue acquiring voltage data 38 for battery cell 26, filtering the acquired voltage data 38, and determining the over-predicted SOC value 48. Using the over-predicted OCV 41 and finally taking remedial action in frame 110 allows preemptive regulation of RESS 24 to avoid extreme battery cell temperatures and other concerns. Alternatively, the method can also be operated using a scaled voltage for each cell group 28, module 30, subgroup 32, and typically on RESS 24. The method can repeat frames 104-110 for each battery cell 26 while RESS 24 is active until at least one of the battery cells 26 is assessed as needing replacement. Alternatively, the method can terminate in frame 112.

[0098] The detailed description and accompanying drawings support and describe this disclosure, but the scope of this disclosure is defined only by the claims. While some of the best modes and other embodiments for implementing the claimed disclosure have been described in detail, various alternative designs and embodiments exist for practicing the disclosure as defined in the appended claims. Furthermore, the features of the embodiments shown in the drawings or the various embodiments mentioned in this description need not be construed as embodiments independent of each other. Rather, it is possible that each of the features described in one example of an embodiment may be combined with one or more desired features from other embodiments, resulting in other embodiments that are not described in words or by reference to the drawings. Therefore, such other embodiments fall within the framework of the appended claims.

Claims

1. A battery system comprising: Multi-cell rechargeable energy storage system (RESS) has multiple battery cells; as well as An electronic controller, which is connected to the RESS and configured to process data from the plurality of battery cells; in: The electronic controller is programmed to have a battery cell open-circuit voltage (OCV) versus state of charge (SOC) data table; The OCV-to-SOC data table is used to calculate the peak OCV change of a representative battery cell at a predetermined capacity and maximum discharge or charge rate; and The electronic controller is configured such that: During the active cycling of the RESS, voltage data is acquired for one of the plurality of battery cells; The acquired voltage data is passed through a first-order hysteresis filter algorithm to generate an over-predicted OCV for one of the plurality of battery cells, such that the over-predicted OCV is calibrated to progress slower during discharge and faster during charging than the calculated peak OCV change by a predetermined margin. The first-order hysteresis filter algorithm includes a first filter gain coefficient, which is calibrated to generate the over-predicted OCV for one of the plurality of battery cells using the voltage data acquired for one of the plurality of battery cells during the active cycling of the RESS. Using the OCV value from the over-predicted OCV, an over-predicted SOC value is determined for one of the plurality of battery cells in the OCV vs. SOC data table, wherein the over-predicted SOC value exceeds the predetermined margin of the true SOC of the one of the plurality of battery cells; and The RESS is adjusted using the over-predicted SOC value determined for one of the plurality of battery cells.

2. The battery system according to claim 1, wherein, The predetermined margin is controlled to be no more than 5% error relative to the actual SOC, which is the over-predicted SOC.

3. The battery system according to claim 1, wherein, The electronic controller is additionally configured to acquire temperature data for one of the plurality of battery cells, and the first-order hysteresis filter algorithm includes a calibrated second filter gain coefficient, which is determined as a function of the temperature and voltage data acquired for one of the plurality of battery cells.

4. The battery system according to claim 1, wherein, The electronic controller is configured to adjust the RESS by controlling the flow rate and / or temperature of the coolant through the RESS to remove heat energy from one of the plurality of battery cells when the over-predicted SOC value is within a predetermined margin.

5. The battery system according to claim 1, wherein, The electronic controller is configured to adjust the RESS by controlling the speed of a cooling fan to remove heat from one of the plurality of battery cells when the over-predicted SOC value is within a predetermined margin.

6. The battery system according to claim 1, wherein, The electronic controller is configured to adjust the RESS by controlling the charging and / or discharging rates of the plurality of battery cells when the over-predicted SOC value is within a predetermined margin.

7. The battery system according to claim 6, wherein, Controlling the charging and / or discharging rate of the plurality of battery cells includes at least one of the following: Limit the power output of the traction motor operatively connected to the RESS; and Adjust the charging current of either the on-board charging station or the off-board charging station.

8. A method for regulating a multi-cell rechargeable energy storage system (RESS) having multiple battery cells, the method comprising: During the active cycling of the RESS, voltage data is acquired for one of the plurality of battery cells, wherein: The electronic controller is programmed to have a battery cell open-circuit voltage (OCV) versus state of charge (SOC) data table; The OCV-to-SOC data table is used to calculate the peak OCV change of a representative battery cell at a predetermined capacity and maximum discharge or charge rate. The acquired voltage data is transmitted via the electronic controller through a first-order hysteresis filter algorithm to generate an over-predicted OCV for one of the plurality of battery cells, such that the over-predicted OCV is calibrated to progress slower during discharge and faster during charging than the calculated peak OCV change by a predetermined margin, including: calibrating a first filter gain coefficient to generate the over-predicted OCV for one of the plurality of battery cells using the voltage data acquired for one of the plurality of battery cells during the active cycling of the RESS; Via the electronic controller, using the OCV value from the over-predicted OCV, an over-predicted SOC value is determined for one of the plurality of battery cells in the OCV vs. SOC data table, wherein the over-predicted SOC value exceeds the predetermined margin of the true SOC of the one of the plurality of battery cells; and The RESS is adjusted via the electronic controller using the over-predicted SOC value determined for one of the plurality of battery cells.

9. The method according to claim 8, wherein, The predetermined margin is controlled to be no more than 5% error relative to the actual SOC, which is the over-predicted SOC.

10. The method of claim 8, further comprising: Temperature data is acquired for one of the plurality of battery cells via the electronic controller, wherein the first-order hysteresis filter algorithm includes a calibrated second filter gain coefficient, the calibrated second filter gain coefficient being determined as a function of the temperature and voltage data acquired for the one of the plurality of battery cells.

11. The method according to claim 8, wherein, The adjustment of the RESS is accomplished by at least one of the following when the over-predicted SOC value is within a predetermined margin: controlling the flow rate and / or temperature of the coolant through the RESS to remove heat from one of the plurality of battery cells, controlling the speed of the cooling fan to remove heat from one of the plurality of battery cells, and controlling the charging and / or discharging rate of the plurality of battery cells.

12. The method according to claim 11, wherein, Controlling the charging and / or discharging rate of the plurality of battery cells includes at least one of the following: Limit the power output of the traction motor operatively connected to the RESS; and Adjust the charging current of either the on-board charging station or the off-board charging station.

13. A motor vehicle comprising: Multi-cell rechargeable energy storage system (RESS) has multiple battery cells; A traction motor, operatively connected to the RESS; as well as An electronic controller, which is connected to each of the RESS and the traction motor and is configured to process data from the plurality of battery cells; in: The electronic controller is programmed to have a battery cell open-circuit voltage (OCV) versus state of charge (SOC) data table; The OCV-to-SOC data table is used to calculate the peak OCV change of a representative battery cell at a predetermined capacity and maximum discharge or charge rate; and The electronic controller is configured such that: During the active cycling of the RESS, voltage data is acquired for one of the plurality of battery cells; The acquired voltage data is passed through a first-order hysteresis filter algorithm to generate an over-predicted OCV for one of the plurality of battery cells, such that the over-predicted OCV is calibrated to progress slower during discharge and faster during charging than the calculated peak OCV change by a predetermined margin. The first-order hysteresis filter algorithm includes a first filter gain coefficient, which is calibrated to generate the over-predicted OCV for one of the plurality of battery cells during the active cycling of the RESS, the over-predicted OCV tracking the acquired voltage data for one of the plurality of battery cells within the predetermined margin. Using the OCV value from the over-predicted OCV, an over-predicted SOC value is determined for one of the plurality of battery cells in the OCV vs. SOC data table, wherein the over-predicted SOC value exceeds the predetermined margin of the true SOC of the one of the plurality of battery cells; and The RESS is adjusted using the over-predicted SOC value determined for one of the plurality of battery cells.

14. The motor vehicle according to claim 13, wherein, The predetermined margin is controlled to be no more than 5% error relative to the actual SOC, which is the over-predicted SOC.

15. The motor vehicle according to claim 13, wherein, The electronic controller is additionally configured to acquire temperature data for one of the plurality of battery cells, and the first-order hysteresis filter algorithm includes a calibrated second filter gain coefficient, which is determined as a function of the temperature and voltage data acquired for one of the plurality of battery cells.

16. The motor vehicle according to claim 13, wherein, The electronic controller is configured to adjust the RESS via at least one of the following when the over-predicted SOC value is within a predetermined margin: controlling the flow rate and / or temperature of the coolant through the RESS to remove heat from one of the plurality of battery cells, controlling the speed of the cooling fan to remove heat from one of the plurality of battery cells, and controlling the charging and / or discharging rate of the plurality of battery cells.

17. The motor vehicle according to claim 16, wherein, Controlling the charging and / or discharging rate of the plurality of battery cells includes at least one of the following: Limit the power output of the traction motor operatively connected to the RESS; and Adjust the charging current of either the on-board charging station or the off-board charging station.

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