Adaptation for charging current limits in rechargeable energy storage systems

Abstract

This application relates to an adaptation for charging current limiting in a rechargeable energy storage system. The battery system includes a rechargeable energy storage system and a battery controller. The rechargeable energy storage system has a fast charging mode and a discharging mode. The battery controller is electrically connected to the rechargeable energy storage system and configured to store a plurality of charging meters containing multiple charging current limit entries, wherein each charging meter corresponds to a unique one of a plurality of initial state of charge (PSC) values; in response to entering the fast charging mode, determining the initial PSC value of the rechargeable energy storage system; in response to the initial PSC value of the rechargeable energy storage system being adjacent to at most two of the initial PSC values, selecting at most two charging meters; and controlling the charging current supplied to the rechargeable energy storage system based on the charging current limit entries in the selected at most two charging meters.

Description

Technical Field

[0001] This disclosure relates to systems and methods for adapting to charging current limitations for rechargeable energy storage systems. Background Technology

[0002] The charging current limitation of rechargeable battery packs is sensitive to the initial state of charge (SOC). Due to the increased polarization accumulated by the battery cells in the pack, the current limitation suitable for avoiding lithium plating is more constrained when the pack starts charging from a lower SOC. Therefore, the conventional approach is to assume that the pack always has a 0% SOC to account for the worst-case charging profile.

[0003] The desired technology is one that adapts to the charging current limitations used in rechargeable energy storage systems. Summary of the Invention

[0004] This document discloses a battery system. The battery system includes a rechargeable energy storage system and a battery controller. The rechargeable energy storage system has a fast charging mode and a discharging mode. The battery controller is electrically connected to the rechargeable energy storage system. The battery controller is configured to store a plurality of charging meters containing a plurality of charging current limit entries, wherein each of the plurality of charging meters corresponds to a unique one of a plurality of initial state of charge (PSC) values; in response to entering the fast charging mode, determine the initial PSC value of the rechargeable energy storage system; in response to the initial PSC value of the rechargeable energy storage system being adjacent to at most two of the plurality of PSC values, select at most two charging meters from the plurality of charging meters; and control the charging current supplied to the rechargeable energy storage system based on the plurality of charging current limit entries in the selected at most two charging meters.

[0005] In one or more embodiments of the battery system, in response to the initial state of charge value of the rechargeable energy storage system matching a single value among a plurality of initial state of charge values, a single one of a plurality of charging meters is selected.

[0006] In one or more embodiments of the battery system, the battery controller is further configured to generate a plurality of intermediate charging current limit entries by interpolation calculations between a plurality of charging current limit entries in at most two charging meters, in response to the initial state of charge (SPC) value of the rechargeable energy storage system falling between two of a plurality of initial SPC values. Control of the charging current provided to the rechargeable energy storage system is based on the plurality of intermediate charging current limit entries.

[0007] In one or more embodiments of the battery system, a first initial state of charge (PSO) among a plurality of initial PSO values ​​is less than a second initial PSO value among a plurality of initial PSO values; and a plurality of charging current limit entries corresponding to the first PSO value cause the rechargeable energy storage system to charge at a lower rate than the plurality of charging current limit entries corresponding to the second PSO value.

[0008] In one or more embodiments of the battery system, the battery controller is further configured to adjust the initial state of charge (PSC) value by a margin value before selecting up to two charging meters. This margin value takes into account inaccuracies in one or more of the measurements used to determine the PSC value, the calculations used to determine the PSC value, and the fact that the rechargeable energy storage system is in a non-rested condition when the PSC value is determined.

[0009] In one or more embodiments of the battery system, the battery charger is further configured to receive multiple charging meters from a test station configured to calibrate multiple charging current limit entries to simulate recharging of the rechargeable energy storage system.

[0010] In one or more embodiments of the battery system, multiple charging current limit entries in multiple charging meters form a three-dimensional surface of the entries, wherein the battery cell potential is a first dimension, the charging rate is a second dimension, and multiple initial state of charge values ​​are a third dimension.

[0011] In one or more embodiments of the battery system, a rechargeable energy storage system and a battery controller may be installed in the vehicle.

[0012] In one or more embodiments of the battery system, the fast charging mode is a DC fast charging mode, in which the vehicle receives DC power from a charging station.

[0013] This document provides a method for adapting charging current limits for a rechargeable energy storage system. The method includes storing multiple charging meters containing multiple charging current limit entries for the rechargeable energy storage system in a battery controller. Each of the multiple charging meters corresponds to a unique one among multiple initial state of charge (POC) values; and the rechargeable energy storage system has a fast charging mode and a discharging mode. The method includes determining the initial POC value of the rechargeable energy storage system in response to entering a fast charging mode; selecting at most two charging meters from the multiple charging meters in response to the initial POC value of the rechargeable energy storage system being adjacent to at most two of the multiple POC values; and controlling the charging current supplied to the rechargeable energy storage system based on the multiple charging current limit entries in the selected at most two charging meters.

[0014] In one or more embodiments of the method, in response to the initial state of charge value of the rechargeable energy storage system matching a single value among a plurality of initial state of charge values, a single one of a plurality of charging meters is selected.

[0015] In one or more embodiments, the method further includes generating a plurality of intermediate charging current limit entries by interpolation calculations between a plurality of charging current limit entries in at most two charging meters, in response to the initial state of charge value of the rechargeable energy storage system falling between two of a plurality of initial state of charge values. Control of the charging current provided to the rechargeable energy storage system is based on the plurality of intermediate charging current limit entries.

[0016] In one or more embodiments of the method, a first initial state of charge (SFC) among a plurality of initial SFC values ​​is less than a second initial SFC value among a plurality of initial SFC values; and a plurality of charging current limit entries corresponding to the first initial SFC value cause the rechargeable energy storage system to charge at a slower rate than the plurality of charging current limit entries corresponding to the second initial SFC value.

[0017] In one or more embodiments, the method further includes adjusting the initial state of charge (PSC) value by a margin value before selecting up to two charging meters. This margin value accounts for inaccuracies in one or more of the measurements used to determine the PSC value, the calculations used to determine the PSC value, and the fact that the rechargeable energy storage system is in a non-resting state when the PSC value is determined.

[0018] In one or more embodiments, the method further includes calibrating a plurality of charging current limit entries to simulate recharging of a rechargeable energy storage system, and transmitting a plurality of charging meters to a battery controller after calibration.

[0019] In one or more embodiments of the method, in response to the initial state of charge value of the rechargeable energy storage system falling between two of a plurality of initial state of charge values, the slower charging meter of up to two charging meters is selected.

[0020] A vehicle is provided herein. The vehicle includes a rechargeable energy storage system, a DC fast charging connector, and a battery controller. The rechargeable energy storage system has a fast charging mode and a discharge mode. The battery controller is electrically connected to the rechargeable energy storage system and the DC fast charging connector. The battery controller is configured to: store a plurality of charging meters containing a plurality of charging current limit entries, wherein each of the plurality of charging meters corresponds to a unique one of a plurality of initial state of charge (PSC) values; determine the initial PSC value of the rechargeable energy storage system in response to entering the fast charging mode; select at most two charging meters from the plurality of charging meters in response to the initial PSC value of the rechargeable energy storage system being adjacent to at most two of the plurality of PSC values; and control the charging current from the DC fast charging connector to the rechargeable energy storage system based on the plurality of charging current limit entries in the selected at most two charging meters.

[0021] In one or more embodiments of the vehicle, the battery controller is further configured to generate a plurality of intermediate charging current limit entries by interpolation calculations between a plurality of charging current limit entries in at most two charging meters, in response to a measured initial state of charge value of the rechargeable energy storage system falling between two of a plurality of initial state of charge values. Control of the charging current provided to the rechargeable energy storage system is based on the plurality of intermediate charging current limit entries.

[0022] In one or more embodiments, the vehicle also includes a charger configured to adjust the charging current to the rechargeable energy storage system in response to a control signal from the battery controller.

[0023] In one or more embodiments, the vehicle further includes an alternator or generator. The rechargeable energy storage system has a normal charging mode. The charger is also configured to direct charging current from a DC fast charging connector when in a fast charging mode and to direct charging current from an alternator or generator when in a normal charging mode.

[0024] Option 1. A battery system comprising:

[0025] A rechargeable energy storage system with fast charging and discharging modes; and

[0026] A battery controller, electrically connected to the rechargeable energy storage system and configured to:

[0027] The system stores multiple charging tables containing multiple charging current limit entries, wherein each of the multiple charging tables corresponds to a unique one among multiple initial state of charge values;

[0028] In response to entering the fast charging mode, the initial state of charge value of the rechargeable energy storage system is determined;

[0029] In response to the fact that the initial state of charge value of the rechargeable energy storage system is adjacent to at most two of the plurality of initial state of charge values, at most two charging meters are selected from the plurality of charging meters; and

[0030] The charging current supplied to the rechargeable energy storage system is controlled based on the plurality of charging current limit entries in the selected up to two charging meters.

[0031] Option 2. The battery system according to Option 1, wherein, in response to the initial state of charge value of the rechargeable energy storage system matching a single value among the plurality of initial state of charge values, a single one of the plurality of charging meters is selected.

[0032] Option 3. The battery system according to Option 1, wherein the battery controller is further configured to generate a plurality of intermediate charging current limit entries by interpolation calculation between the plurality of charging current limit entries in at most two charging tables in response to the initial state of charge value of the rechargeable energy storage system falling between two of the plurality of initial state of charge values; wherein the control of the charging current provided to the rechargeable energy storage system is based on the plurality of intermediate charging current limit entries.

[0033] Option 4. The battery system according to Option 1, wherein a first initial state of charge (PSC) among the plurality of initial PSC values ​​is less than a second initial PSC value among the plurality of initial PSC values; and the plurality of charging current limit entries corresponding to the first PSC value cause the rechargeable energy storage system to charge at a lower rate than the plurality of charging current limit entries corresponding to the second PSC value.

[0034] Option 5. The battery system according to Option 1, wherein the battery controller is further configured to: adjust the initial state of charge value by a margin value before selecting the at most two charging meters; wherein the margin value takes into account inaccuracies in one or more of the measurements used to determine the initial state of charge value, the calculations used to determine the initial state of charge value, and the rechargeable energy storage system being in a non-resting state when the initial state of charge value is determined.

[0035] Option 6. The battery system according to Option 1, wherein the battery charger is further configured to receive a plurality of charging meters from a test station, the test station being configured to calibrate the plurality of charging current limit entries to simulate the recharging of the rechargeable energy storage system.

[0036] Option 7. The battery system according to Option 1, wherein the plurality of charging current limit entries in the plurality of charging meters form a three-dimensional surface of the entries, wherein the battery cell potential is a first dimension, the charging rate is a second dimension, and the plurality of initial state of charge values ​​are a third dimension.

[0037] Option 8. The battery system according to Option 1, wherein the rechargeable energy storage system and the battery controller can be installed in a vehicle.

[0038] Option 9. The battery system according to Option 8, wherein the fast charging mode is a DC fast charging mode, in which the vehicle receives DC power from the charging station.

[0039] Option 10. A method for adapting to charging current limitations for rechargeable energy storage systems, comprising:

[0040] The battery controller stores multiple charging tables containing multiple charging current limit entries for a rechargeable energy storage system, wherein each of the multiple charging tables corresponds to a unique one among multiple initial state of charge values; and the rechargeable energy storage system has a fast charging mode and a discharge mode;

[0041] In response to entering the fast charging mode, the initial state of charge value of the rechargeable energy storage system is determined;

[0042] In response to the fact that the initial state of charge value of the rechargeable energy storage system is adjacent to at most two of the plurality of initial state of charge values, at most two charging meters are selected from the plurality of charging meters; and

[0043] The charging current supplied to the rechargeable energy storage system is controlled based on the plurality of charging current limit entries in the selected up to two charging meters.

[0044] Option 11. The method according to Option 10, wherein, in response to the initial state of charge value of the rechargeable energy storage system matching a single value among the plurality of initial state of charge values, a single one of the plurality of charging meters is selected.

[0045] Option 12. The method according to Option 10 further includes:

[0046] In response to the initial state of charge value of the rechargeable energy storage system falling between two of the plurality of initial state of charge values, a plurality of intermediate charging current limit entries are generated by interpolation calculation between the plurality of charging current limit entries in the at most two charging tables; wherein the control of the charging current provided to the rechargeable energy storage system is based on the plurality of intermediate charging current limit entries.

[0047] Option 13. The method according to Option 10, wherein a first initial state of charge value among the plurality of initial state of charge values ​​is less than a second initial state of charge value among the plurality of initial state of charge values; and the plurality of charging current limit entries corresponding to the first initial state of charge value cause the rechargeable energy storage system to charge at a slower rate than the plurality of charging current limit entries corresponding to the second initial state of charge value.

[0048] Option 14. The method according to Option 10 further includes:

[0049] Before selecting the at most two charging meters, the initial state of charge (PSC) value is adjusted by a margin value, wherein the margin value takes into account inaccuracies in one or more of the measurements used to determine the PSC value, the calculations used to determine the PSC value, and the rechargeable energy storage system being in a non-resting state when the PSC value is determined.

[0050] Option 15. The method according to Option 10 further includes:

[0051] The plurality of charging current limit entries are calibrated to simulate the recharging of the rechargeable energy storage system; and

[0052] After the calibration, the plurality of charging meters are transmitted to the battery controller.

[0053] Option 16. The method according to Option 10, wherein, in response to the initial state of charge value of the rechargeable energy storage system falling between two of the plurality of initial state of charge values, the slower charging meter among the at most two charging meters is selected.

[0054] Option 17. A vehicle comprising:

[0055] A rechargeable energy storage system with fast charging and discharging modes;

[0056] DC fast charging connector; and

[0057] A battery controller, electrically connected to the rechargeable energy storage system and the DC fast charging connector, is configured as follows:

[0058] The system stores multiple charging tables containing multiple charging current limit entries, wherein each of the multiple charging tables corresponds to a unique one among multiple initial state of charge values;

[0059] In response to entering fast charging mode, the initial state of charge value of the rechargeable energy storage system is determined;

[0060] In response to the fact that the initial state of charge value of the rechargeable energy storage system is adjacent to at most two of the plurality of initial state of charge values, at most two charging meters are selected from the plurality of charging meters; and

[0061] The charging current from the DC fast charging connector to the rechargeable energy storage system is controlled based on the plurality of charging current limit entries in the selected up to two charging meters.

[0062] Option 18. The vehicle according to Option 17, wherein the battery controller is further configured to: generate a plurality of intermediate charging current limit entries by interpolation calculation between the plurality of charging current limit entries in the at most two charging meters, in response to the measured initial state of charge value of the rechargeable energy storage system falling between two of the plurality of initial state of charge values; wherein the control of the charging current provided to the rechargeable energy storage system is based on the plurality of intermediate charging current limit entries.

[0063] Option 19. The vehicle according to Option 17 further includes a charger configured to adjust the charging current to the rechargeable energy storage system in response to a control signal from the battery controller.

[0064] Option 20. The vehicle according to Option 19 further includes an alternator or generator, wherein the rechargeable energy storage system has a normal charging mode, and the charger is further configured to guide charging current from the DC fast charging connector when in the fast charging mode, and to guide charging current from the alternator or generator when in the normal charging mode.

[0065] The foregoing features and advantages, as well as other features and advantages, of this disclosure will become apparent when considered in conjunction with the accompanying drawings and from the following detailed description of the best mode for carrying out this disclosure. Attached Figure Description

[0066] Figure 1 This is a schematic floor plan showing the background of the system.

[0067] Figure 2This is a schematic diagram of a calibration system according to one or more exemplary embodiments.

[0068] Figure 3 It is a diagram of a set of charging current limit entries according to one or more exemplary embodiments.

[0069] Figure 4 This is a flowchart of a method for adapting to charging current limits for a rechargeable energy storage system, according to one or more exemplary embodiments.

[0070] Figure 5 It is a graph that returns the state of charge according to one or more exemplary embodiments.

[0071] Figure 6 It is a graph of the peak charging power curve according to one or more exemplary embodiments. Detailed Implementation

[0072] Embodiments of this disclosure provide systems and techniques to improve DC fast charging (DCFC) charging time for rechargeable energy storage systems (e.g., battery packs) by modulating between high-voltage battery charging current limit tables used to control fast charging current. The advantage of different charging current limits is that less polarized DC fast charging current limits are used for higher onset state of charge (PSC) values ​​of the rechargeable energy storage system. This system and technique generally allow for robust limits for lower PSC values ​​while also allowing for greater capacity limits for customers charging at higher PSC values. The battery controller can optimize DC fast charging time by interpolating between charging current limit tables selected based on PSC values.

[0073] In one or more embodiments, the test station in the calibration system can characterize the lithium plating capability of the rechargeable energy storage system through cell-level and battery pack-level testing at multiple initial state of charge (SOC) values. The resulting charging current limit entries are grouped into charging meters, each associated with a specific (or distinguishable) SOC value, and each meter represents a fast-charging profile. The charging meters are stored in the vehicle carrying the rechargeable energy storage system. This technique takes into account sensing inaccuracies and customer diversity to apply biases to the calibration meters.

[0074] The battery controller uses the state of charge (health and / or voltage) of the rechargeable energy storage system as input to the process, which can select one of the stored calibration tables and / or interpolate between two of the stored calibration tables, and then select the optimal limit to control fast charging.

[0075] refer to Figure 1The diagram shows a schematic plan view of the background of system 80. System 80 can be implemented as a vehicle 82 connectable to a charging station 84 via a charging cable 86. Vehicle 82 includes a DC fast charging connector 88, a power inverter module 90, a charger 92, one or more electric motors 94 (one shown), a generator 96, and a battery system 100. Battery system 100 includes a rechargeable energy storage system 102 and a battery controller 104. Rechargeable energy storage system 102 includes a sensor unit 106. Rechargeable energy storage system 102 may have a discharge mode 110, a normal charging mode 112, and a fast charging mode 114. Battery controller 104 stores multiple charging meters 116.

[0076] A charging control signal (e.g., CC) is generated by the battery controller 104 and transmitted to the charger 92. The charging control signal CC conveys data used by the battery controller 104 to control the output voltage and / or output current of the charger 92. A power control signal (e.g., PC) is exchanged between the battery controller 104 and the power inverter module 90. The power control signal PC transmits data and information for controlling the electric motor 94 and for charging and discharging the rechargeable energy storage system 102. A sensor signal (e.g., SU) is generated by the sensor unit 106 and transmitted to the battery controller 104. The sensor signal SU can convey data acquired by the sensor unit 106 from the battery cells within the rechargeable energy storage system 102.

[0077] Vehicle 82 may include, but is not limited to, moving objects such as automobiles, trucks, motorcycles, hybrid vehicles, electric vehicles, hybrid electric vehicles, boats, trains, and / or aircraft. In some embodiments, vehicle 82 may include stationary objects such as billboards, kiosks, backup power systems (e.g., uninterruptible power supplies), and / or awnings. Other types of vehicle 82 may be implemented to meet the design criteria of a particular application. Where vehicle 82 is moving, vehicle 82 typically uses an electric motor 94 and / or an internal combustion engine to drive the wheels that propel vehicle 82 on the ground and / or roads.

[0078] Charging station 84 is implemented as a DC fast charging (DCFC) charging station. Charging station 84 operates to provide DC power for rapid charging of vehicle 82 (e.g., rechargeable energy storage system 102) via charging cable 86. Fast charging is typically completed in less than 25 minutes. In various embodiments, charging station 84 can deliver high-voltage power in the range of approximately 50,000 watts (W) to 150,000 W at a charging current of at least 100 amperes (A) and up to 500 A at approximately 300 volts DC (Vdc) to 500 Vdc.

[0079] Connector 88 is implemented as a DC fast charging connector. Connector 88 operates to receive high-voltage electrical power from charging station 84 via charging cable 86. In some embodiments, connector 88 may include a socket for alternating current (AC) power. Various designs of connector 88 may include a socket for low-voltage electrical power (e.g., 12 Vdc) to charge one or more conventional batteries used to power electrical accessories within vehicle 82 and start an internal combustion engine (if present).

[0080] The power inverter module 90 is implemented as a DC-to-AC converter / switching circuit. Controlled by data received from the battery controller 104 in the power control signal PC, the power inverter module 90 operates to deliver power to the electric motor 94 and the battery system 100. When the rechargeable energy storage system 102 is in discharge mode 110, the power inverter module 90 operates to convert the DC high-voltage power received from the rechargeable energy storage system 102 into AC power to power the electric motor 94. When the rechargeable energy storage system 102 is in normal charging mode 112 or fast charging mode 114, the power inverter module 90 can direct high-voltage power from the charger 92 to the rechargeable energy storage system 102.

[0081] The power inverter module 90 can also connect the high-voltage system of vehicle 82 to the low-voltage system and can perform a variety of different functions with this capability. In various embodiments, the power inverter module 90 includes an accessory power module (APM) circuit that is electrically connected to both the high-voltage bus and the low-voltage bus in vehicle 82, enabling the exchange of electrical energy between them. The power inverter module 90 may include any combination of processing and storage resources, as well as transformers and / or other electrical components for transferring or exchanging electrical power between different parts, devices, modules, etc., of vehicle 82.

[0082] Charger 92 is implemented as a controllable battery charger. Controlled by a charging control signal CC, charger 92 operates to direct high-voltage power from connector 88 and generator 96 to power inverter module 90. The voltage and / or current of the high-voltage power delivered by charger 92 is variable, based on data received from battery controller 104 in the charging control signal CC. Charger 92 directs high-voltage power received from charging station 84 to provide rapid recharging for battery system 100. In the case where vehicle 82 is propelled by an internal combustion engine, charger 92 also directs high-voltage power received from generator 96 to provide normal recharging for battery system 100.

[0083] The electric motor 94 is implemented as a multiphase (e.g., three-phase) motor. The electric motor 94 operates to propel the vehicle 82 using electrical power stored in the battery system 100. The electric motor 94 may include any suitable type of electric motor known in the art. The electrical power consumed by the electric motor 94 may be provided by the battery system 100 and / or the generator 96 under the control of the battery controller 104. Although the electric motor 94 is depicted as a discrete device, other embodiments may be implemented in which the electric motor 94 is integrated with or otherwise combined with a transmission, generator 96, etc.

[0084] The generator 96 is implemented as a generator, alternator, or inverter. When implemented as a high-voltage power source, the generator uses mechanical motion provided by an internal combustion engine to generate high-voltage electrical power for charging the battery system 100. In some embodiments, the generator 96 may also operate to generate low-voltage electrical power (e.g., 12 Vdc) for powering electrical accessories within the vehicle 82. Any number of suitable generators 96 known in the art can be used. When implemented as an inverter (e.g., in an all-electric vehicle), the generator 96 operates to convert the high-voltage electrical power available in the battery system 100 into low-voltage electrical power.

[0085] The battery system 100 can be implemented as a high-voltage rechargeable battery system. The battery system 100 operates to store energy used by the electric motor 94. In charging mode, the battery system 100 can receive current from the generator 96 or from the charging station 84. In discharging mode, the battery system 100 can provide current to the power inverter module 90 to operate the electric motor 94.

[0086] The rechargeable energy storage system 102 is implemented as a high-voltage battery pack. The rechargeable energy storage system 102 is configured to store electrical energy. The rechargeable energy storage system typically operates to receive electrical power from the power inverter module 90 and provide electrical power to the power inverter module 90. The rechargeable energy storage system may include multiple battery modules electrically connected in series and / or parallel. In various embodiments, the rechargeable energy storage system can provide a DC (direct current) potential of approximately 200 to 1,000 volts. Other battery voltages may be implemented to meet the design requirements of specific applications.

[0087] In various embodiments, the rechargeable energy storage system 102 can be any suitable battery type known in the art. Examples of suitable battery types include all types of lithium-ion (e.g., lithium iron phosphate, lithium nickel manganese cobalt, lithium iron sulfide, and lithium polymers), lead-acid, advanced lead-acid, nickel-metal hydride (NiMH), nickel-cadmium (NiCd), zinc bromide, sodium-nickel chloride (NaNiCl), zinc-air, vanadium redox, and others.

[0088] Sensor unit 106 operates to sense, monitor, evaluate, control, and manage certain charging and / or discharging functions associated with rechargeable energy storage system 102. In some embodiments, sensor unit 106 is a battery pack control module (BPCM) integrated within rechargeable energy storage system 102 and includes one or more battery sensors coupled to rechargeable energy storage system 102, as well as processing and memory resources. Battery sensors may include temperature sensors, state of charge (SOC) sensors, voltage and / or current sensors, and any other suitable battery sensors, and provide readings that can be processed by the sensor unit itself and / or forwarded to other devices, components, modules, etc. For example, various battery conditions may be collected, processed, and stored by sensor unit 106, and then transmitted to battery controller 104 as sensor signals SU. Although the rechargeable energy storage system 102 and the sensor unit 106 are schematically shown herein as integrated into a single component, it should be understood that other embodiments may involve mounting the sensor unit 106 externally to the rechargeable energy storage system 102 and connecting battery-mounted sensors to the sensor unit 106 via a communication medium.

[0089] The rechargeable energy storage system 102 typically operates in one of three modes: discharge mode 110, normal charging mode 112, and fast charging mode 114. In discharge mode 110, the rechargeable energy storage system 102 provides a discharge current (D) to the power inverter module 90 to operate the motor 94. In normal charging mode 112, the rechargeable energy storage system 102 receives a charging current (C) generated by the generator 96. In fast charging mode 114, the rechargeable energy storage system 102 receives a charging current C as a DC fast charging (FC) current generated by the charging station 84.

[0090] The battery controller 104 includes any of a variety of electronic processing devices, memory devices, input / output (I / O) devices, and / or other known components, and is capable of performing various control and / or communication-related functions. The battery controller 104 operates to store a charging meter 116 containing multiple charging current limit entries; upon entering fast charging mode 114, it determines the initial state of charge (PBC) value of the rechargeable energy storage system 102; in response to at most two of the PBC values ​​of the rechargeable energy storage system 102 that are adjacent to (or similar to) the initial PBC values ​​of the charging meters, it selects at most two of the charging meters; and based on the charging current limit entries in the selected at most two charging meters, it controls the charging current supplied to the rechargeable energy storage system 102. Each charging meter corresponds to a unique initial PBC value.

[0091] The battery controller 104 is also operable to store various sensor readings (e.g., battery temperature, SOC, voltage, and current sensor readings), data structures, software, etc. The battery controller 104 can store relevant characteristics and background information, including but not limited to battery state-of-charge limits, battery voltage limits, battery current limits, battery temperature limits, and temperature profiles. The battery controller 104 can be electronically coupled to other vehicle devices and modules via suitable vehicle communication connections and can interact with other devices as appropriate.

[0092] According to specific embodiments, the battery controller 104 may be a standalone vehicle electronic module (e.g., a hybrid power control module (HCM), a vehicle control integrated module (VCIM), a traction power inverter module (TPIM), a battery power inverter module (BPIM), a portion of the instrument cluster itself, an engine control module (ECM), etc.). The battery controller 104 may be incorporated into or included within another vehicle electronic module (e.g., a powertrain control module or a hybrid power control module), or it may be part of a larger network or system (e.g., a battery management system (BMS), a vehicle energy management system, a hybrid power control system, etc.), to name just a few possibilities. The battery controller 104 may also be part of or interact with a system that determines or governs desired hybrid operating modes (e.g., acceleration, braking, idling, stopping, etc.) and accordingly implements electric power management actions.

[0093] The charging meters 116 are implemented as charging limit meters, each containing multiple charging current limit entries. Each charging meter 116 corresponds to a unique initial state of charge value. At least during fast charging mode 114, the battery controller 104 uses one or two charging current limit entries from the charging meters 116 each time to manage the charging current C supplied to the rechargeable energy storage system 102.

[0094] refer to Figure 2 The diagram illustrates an exemplary embodiment of a calibration system 140 according to one or more exemplary embodiments. The calibration system 140 includes a test station 142, a rechargeable energy storage system 102, and a corresponding battery controller 104.

[0095] Test signals (TS) are exchanged between the rechargeable energy storage system 102 and the test station 142. The test signal TS contains test commands and test results for testing the fast charging of the rechargeable energy storage system 102. A calibration signal (CL) is generated by the test station 142 and transmitted to the battery controller 104. The calibration signal CL carries a charging meter 116 that simulates recharging or fast recharging of the rechargeable energy storage system 102.

[0096] Test station 142 operates to establish various initial state of charge (SOC) conditions via test signal TS, and subsequently measures the charging rate characteristics of rechargeable energy storage system 102 using the SOC values. Test station 142 uses the measurements to calculate a charging current limit entry for each charging meter 116, each charging meter 116 corresponding to one of the SOC values. The charging meters 116 are then transmitted to battery controller 104 via calibration signal CL. Therefore, the charging meters 116 stored in battery controller 104 are customized for a specific rechargeable energy storage system 102.

[0097] refer to Figure 3 A graph 160 illustrates an exemplary set of charging current limit entries according to one or more exemplary embodiments. The first axis 162 of graph 160 represents the battery cell potential in volts. The second axis 164 of graph 160 represents the C-rate (current divided by the battery's nominal capacity). The third axis 166 represents the initial state of charge value in percentage terms. In this example, the conditions are 25 degrees Celsius, 1.67C-rate, constant current, constant anode potential = 0V vs. Li / Li. + The three axes 162, 164, and 166 provide the battery cell potential as the first dimension, the charging rate as the second dimension, and the initial state of charge as the third dimension.

[0098] The 0% start state of charge condition (curve 170) generally provides a series of calibration limits that protect against all customer use. The 20% start state of charge condition (curve 172) provides a series of calibration limits where the rechargeable energy storage system 102 begins fast charging at approximately 20% state of charge. The 40% start state of charge condition (curve 174) provides a series of calibration limits where the rechargeable energy storage system 102 begins fast charging at approximately 40% state of charge. The 50% start state of charge condition (curve 176) provides a series of calibration limits where the rechargeable energy storage system 102 begins fast charging at approximately 50% state of charge. Curves 172 to 176 show that when the start state of charge is above 0%, the rechargeable energy storage system 102 can charge at a higher rate to a higher cell potential. A set of charging current limit entries for each curve 170-176 is provided by test station 142 ( Figure 2 The data is collected in the charging meter 116 and loaded into the battery controller 104.

[0099] For initial state of charge (PSC) values ​​that do not fall directly on curves 170-176, the battery controller 104 may perform interpolation calculations between the two most recent charge meters 116 to generate an intermediate set of charging current limit entries. These intermediate charging current limit entries are then used by the battery controller 104 to control the fast charging of the rechargeable energy storage system 102. In various embodiments, the interpolation may be proportional to the distance between the measured PSC value and the most recent initial PSC value. For example, for two of the charge meters 116, a 30% PSC value may fall between a 20% first initial PSC value and a 40% second initial PSC value. Therefore, the battery controller 104 may weight each intermediate current limit entry to half of the corresponding entry in the 20% initial PSC charge meter 116 and half of the corresponding entry in the 40% initial PSC charge meter 116. For a 42% initial state of charge (SOC) value, the battery controller 104 can weight each intermediate charging current limit entry to 4 / 5 of the corresponding entry in the 40% SOC charging table 116 and 1 / 5 of the corresponding entry in the 50% SOC charging table 116. Other interpolation techniques can be implemented to meet the design criteria of a specific application. In various embodiments, the second-lowest charging table can be selected to provide a conservative approach. For example, if the SOC value is 30%, a table corresponding to a 20% SOC value can be used.

[0100] Using a charging meter 116 calibrated for a specific initial state of charge (SOC) value for the rechargeable energy storage system 102, and interpolating charging current limit entries between the charging meters 116, the battery controller 104 has a three-dimensional surface with entry 178, which can be used to optimize DCFC charging time based on the SOC value of the rechargeable energy storage system 102. The three-dimensional surface of entry 178 allows the battery system 100 to charge rapidly to near the true limits of the rechargeable energy storage system 102.

[0101] refer to Figure 4 This diagram illustrates a flowchart of an example method 200 for adapting to charging current limitations for a rechargeable energy storage system 102, according to one or more exemplary embodiments. Method (or process) 200 may be implemented by a battery system 100. Method 200 includes steps 202, 204, 206, 208, 210, 212, 214, 216, 218, and 220. The order of the steps is shown as a representative example. Other step sequences may be implemented to meet the standards of a particular application.

[0102] The method typically begins at step 202 with the rechargeable energy storage system 102 entering fast charging mode 114. In step 204, sensor unit 106 measures the current of the rechargeable energy storage system 102 and compares it to a threshold to determine if the rechargeable energy storage system 102 is approaching a rested condition. Controller 104 typically knows how long the current has been below the threshold and also knows that this time should meet a minimum threshold. The initial state of charge (SOC) value can also be the last stored value calculated by the process in controller 104. If the rechargeable energy storage system 102 is not in a rested condition when the SOC value is determined, battery controller 104 may default to using the 0% initial SOC charging meter 116 in step 206. If the rechargeable energy storage system 102 is approaching or in a rested condition (e.g., approximately no current flowing in or out), in step 208, battery controller 104 calculates the SOC value for the rechargeable energy storage system 102. This SOC value is typically based on the measured voltage of the battery cell or the entire battery pack.

[0103] In step 210, the battery controller 104 subtracts a calibrable margin value from the initial state of charge (PSC) value. Reducing the PSC value typically takes into account issues such as sensor inaccuracies in the sensor unit 106, computational inaccuracies in determining the PSC value from the measured voltage, and / or the rechargeable energy storage system 102 not being fully at rest. Other issues may be considered to meet the design criteria for specific applications.

[0104] In step 212, the battery controller 104 compares the adjusted initial state of charge (PSC) value from step 208 with the initial PSC value corresponding to the charging meter 116. In step 214, if the PSC value matches or nearly matches (e.g., ±1%) a specific one of the initial PSC values, the battery controller 104 selects the corresponding matching charging meter 116. Otherwise, in step 216, the battery controller 104 selects two similar initial PSC values ​​and interpolates the charging current limit entries in the two corresponding charging meters 116 to create an intermediate set of charging current limit entries. In some embodiments, in step 216, the battery controller 104 may select the slower charging meter 116 among the two similar charging meters 116 instead of interpolating between the two charging meters 116.

[0105] In step 218, the battery controller 104 uses the charging current limit entry and the initial state of charge value to rapidly charge the rechargeable energy storage system 102. After the rapid charging is complete, method 200 may end at step 220.

[0106] refer to Figure 5 A graph 240 is shown illustrating the state of charge returned by an example according to one or more exemplary embodiments. The first axis 242 of graph 240 represents time in minutes. The second axis 244 of graph 240 represents the state of charge returned by the battery system 100 as a percentage. The example conditions are 25 degrees Celsius, 1.67C rate constant current / constant anodic potential = 0V vs. Li / Li. + .

[0107] Curve 246 illustrates an example state-of-charge return, where the rechargeable energy storage system 102 is rapidly charged according to the charging current limit entry in the 0% initial state-of-charge meter 116. Curve 248 illustrates an example state-of-charge return, where the rechargeable energy storage system 102 is rapidly charged at the maximum rate according to the charging current limit entry in the 50% initial state-of-charge meter 116. Curve 248 shows a greater than 40% improvement in charging time when using the 50% initial state-of-charge meter 116 instead of the 0% initial state-of-charge meter 116.

[0108] refer to Figure 6 A graph 260 illustrates an example peak charging power curve according to one or more exemplary embodiments. The first axis 262 of graph 260 represents the initial state of charge (SOC) of the rechargeable energy storage system 102 in percentage terms. The second axis 264 of graph 260 represents the charging power of the rechargeable energy storage system 102 in kilowatts. The example conditions are 25 degrees Celsius, a peak current of 500 amperes, and a variable SOC.

[0109] Curve 266 shows the peak charging power based on the charging meter 116 at 0% initial state of charge. Curve 268 shows the peak charging power based on the charging meter 116 at 20% initial state of charge. Curve 270 shows the peak charging power based on the charging meter 116 at 40% initial state of charge. Curve 272 shows the peak charging power based on the charging meter 116 at 50% initial state of charge. As shown by curves 266-272, the peak charging power increases as the initial state of charge of the rechargeable energy storage system 102 increases. Furthermore, curves 266-272 show that the power used for the constant state of charge is higher when starting from a higher initial state of charge.

[0110] Embodiments of this disclosure reduce DC fast charging time by modulating between high-voltage battery charging current limiting tables selected based on the initial state of charge (PSC) of the rechargeable energy storage system. This technique generally optimizes DC fast charging time by selecting the charging table using the PSC of the rechargeable energy storage system and / or by interpolating between two nearest charging tables. This technique allows for robust limiting for lower PSC values ​​and also allows for greater capacity limiting for customers charging at higher PSC values. For customers plugging into charging stations with higher PSC values, charging speed is increased without increasing the unit price of the battery cell / pack.

[0111] While the best mode for carrying out this disclosure has been described in detail, those skilled in the art related to this disclosure will recognize various alternative designs and embodiments for carrying out this disclosure within the scope of the appended claims.

Claims

1. A battery system comprising: a rechargeable energy storage system operating in one of three modes: a discharge mode in which the rechargeable energy storage system provides a discharge current to operate a motor, a normal charge mode in which the rechargeable energy storage system receives a charge current generated by a generator, and a fast charge mode in which the rechargeable energy storage system receives a charge current as a direct current fast charge current generated by a charging station; and a battery controller electrically coupled to the rechargeable energy storage system and configured to: store a plurality of charge tables containing a plurality of charge current limit entries, wherein each of the plurality of charge tables corresponds to a unique one of a plurality of initial state of charge values; in response to entering the fast charge mode, determine a starting state of charge value of the rechargeable energy storage system; in response to the starting state of charge value of the rechargeable energy storage system being adjacent to at most two of the plurality of initial state of charge values, select at most two charge tables from the plurality of charge tables; and control a charge current provided to the rechargeable energy storage system based on the plurality of charge current limit entries in the at most two selected charge tables.

2. The battery system of claim 1, wherein, in response to the starting state of charge value of the rechargeable energy storage system matching a single value of the plurality of initial state of charge values, a single one of the plurality of charge tables is selected.

3. The battery system of claim 1, wherein, the battery controller is further configured to, in response to the starting state of charge value of the rechargeable energy storage system falling between two of the plurality of initial state of charge values, generate a plurality of intermediate charge current limit entries by interpolating between the plurality of charge current limit entries in the at most two charge tables; wherein the control of the charge current provided to the rechargeable energy storage system is based on the plurality of intermediate charge current limit entries.

4. The battery system of claim 1, wherein, a first initial state of charge value of the plurality of initial state of charge values is less than a second initial state of charge value of the plurality of initial state of charge values; and the plurality of charge current limit entries corresponding to the first initial state of charge value cause the rechargeable energy storage system to charge at a lower rate than the plurality of charge current limit entries corresponding to the second initial state of charge value.

5. The battery system of claim 1, wherein, the battery controller is further configured to, prior to the selection of the at most two charge tables, adjust the starting state of charge value by a margin value; wherein the margin value accounts for inaccuracies in one or more of a measurement used to determine the starting state of charge value, a calculation used to determine the starting state of charge value, and a non-resting condition of the rechargeable energy storage system at the time the starting state of charge value is determined.

6. The battery system of claim 1, wherein, the battery charger is further configured to receive the plurality of charge tables from a test station configured to calibrate the plurality of charge current limit entries to simulate recharging of the rechargeable energy storage system.

7. The battery system of claim 1, wherein, The plurality of charge current limit entries in the plurality of charge tables forms a three-dimensional surface of entries with battery cell potential as a first dimension, charge rate as a second dimension, and the plurality of initial state of charge values as a third dimension.

8. The battery system of claim 1, wherein, The rechargeable energy storage system and the battery controller can be installed in a vehicle.

9. The battery system of claim 8, wherein, The fast charge mode is a direct current fast charge mode in which the vehicle receives direct current power from a charging station.

10. A method for adapting a charge current limit for a rechargeable energy storage system, comprising: storing, in a battery controller, a plurality of charge tables containing a plurality of charge current limit entries for a rechargeable energy storage system, wherein each of the plurality of charge tables corresponds to a unique one of a plurality of initial state of charge values; and the rechargeable energy storage system operates in one of three modes: a discharge mode in which the rechargeable energy storage system provides a discharge current to operate a motor, a normal charge mode in which the rechargeable energy storage system receives a charge current generated by an electrical generator, and a fast charge mode in which the rechargeable energy storage system receives a charge current that is a direct current fast charge current generated by a charging station; in response to entering the fast charge mode, determining a starting state of charge value of the rechargeable energy storage system; in response to the starting state of charge value of the rechargeable energy storage system being adjacent to at most two of the plurality of initial state of charge values, selecting at most two charge tables from the plurality of charge tables; and controlling a charge current provided to the rechargeable energy storage system based on the plurality of charge current limit entries in the at most two selected charge tables.

11. The method of claim 10, wherein, In response to the starting state of charge value of the rechargeable energy storage system matching a single value of the plurality of initial state of charge values, a single one of the plurality of charge tables is selected.

12. The method of claim 10, further comprising: in response to the starting state of charge value of the rechargeable energy storage system falling between two of the plurality of initial state of charge values, generating a plurality of intermediate charge current limit entries by interpolating between the plurality of charge current limit entries in the at most two charge tables; wherein the controlling of the charge current provided to the rechargeable energy storage system is based on the plurality of intermediate charge current limit entries.

13. The method of claim 10, wherein, a first initial state of charge value of the plurality of initial state of charge values is less than a second initial state of charge value of the plurality of initial state of charge values; and the plurality of charge current limit entries corresponding to the first initial state of charge value cause the rechargeable energy storage system to charge at a slower rate than the plurality of charge current limit entries corresponding to the second initial state of charge value.

14. The method of claim 10, further comprising: adjusting the start state of charge value by a margin value prior to the selection of the at most two charge tables; wherein the margin value accounts for inaccuracies in one or more of measurements used to determine the start state of charge value, calculations used to determine the start state of charge value, and the state of the rechargeable energy storage system when the start state of charge value is determined.

15. The method of claim 10, further comprising: calibrating the plurality of charge current limit entries to emulate recharging of the rechargeable energy storage system; and transmitting the plurality of charge tables to the battery controller after the calibration.

16. The method of claim 10, wherein, selecting a slower of the at most two charge tables in response to the start state of charge value of the rechargeable energy storage system falling between two of the plurality of initial state of charge values.

17. A vehicle, comprising: a rechargeable energy storage system operating in one of three modes: a discharge mode in which the rechargeable energy storage system provides a discharge current to operate a motor, a normal charge mode in which the rechargeable energy storage system receives a charge current generated by a generator, and a fast charge mode in which the rechargeable energy storage system receives a charge current as a direct current fast charge current generated by a charging station; a direct current fast charge connector; and a battery controller electrically coupled to the rechargeable energy storage system and the direct current fast charge connector and configured to: store a plurality of charge tables containing a plurality of charge current limit entries, wherein each of the plurality of charge tables corresponds to a unique one of a plurality of initial state of charge values; determine a start state of charge value of the rechargeable energy storage system in response to entering a fast charge mode; select at most two charge tables from the plurality of charge tables in response to the start state of charge value of the rechargeable energy storage system being adjacent to at most two of the plurality of initial state of charge values; and control a charge current from the direct current fast charge connector to the rechargeable energy storage system based on the plurality of charge current limit entries in the selected at most two charge tables.

18. The vehicle of claim 17, wherein, the battery controller is further configured to, in response to the measured start state of charge value of the rechargeable energy storage system falling between two of the plurality of initial state of charge values, generate a plurality of intermediate charge current limit entries by interpolating between the plurality of charge current limit entries in the at most two charge tables; wherein the control of the charge current provided to the rechargeable energy storage system is based on the plurality of intermediate charge current limit entries.

19. The vehicle of claim 17, further comprising a charger configured to adjust a charge current to the rechargeable energy storage system in response to a control signal from the battery controller.

20. The vehicle of claim 19, further comprising an alternator or generator, wherein, The rechargeable energy storage system has a normal charging mode, and the charger is further configured to direct charging current from the DC fast charging connector when in the fast charging mode, and to direct charging current from the alternator or the generator when in the normal charging mode.

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