Current measurement arrangements for precision current monitoring in battery applications

Abstract

A battery management system (BMS) associated with a battery is described. The battery includes one or more battery cells. The BMS includes a first shunt and a second shunt. The first shunt has a first shunt resistance value for measuring a current within an upper subrange of a range of current. The second shunt has a second shunt resistance value for measuring the current within a lower subrange of the range of current. The BMS is configured to determine a current measurement mode for measuring the current associated with the battery using one or both of the first shunt and the second shunt, where the current measurement mode being determined based on one or more parameters, measure the current based on the current measurement mode, and perform one or more actions based on one or both of the current measurement mode and the measured current.

Description

[0001] CURRENT MEASUREMENT ARRANGEMENTS FOR PRECISION CURRENT

[0002] MONITORING IN BATTERY APPLICATIONS

[0003] TECHNICAL FIELD

[0004] This disclosure relates to battery parameter measurements and in particular to a method, apparatus and system for current monitoring in batteries.

[0005] BACKGROUND

[0006] Batteries are an integral part of many devices, including vehicles. Vehicle batteries may be used to provide starting energy such as to start an internal combustion engine, to provide locomotive energy such as to drive electric motors coupled to wheels and / or to provide energy to power auxiliary vehicle devices such as lights, multi-media, anti-lock braking systems, power steering, etc. As such, it is desirable to have knowledge of the state of charge and / or health of the battery. This is particularly relevant for safety scenarios where knowledge that the battery has enough charge to power the vehicle’s safety equipment, such as anti-lock braking systems, air bags, pretensioners, etc. This may involve monitoring a number of battery parameters, including battery current.

[0007] In order to obtain as accurate a measurement of the state of charge as possible, accurate measurement of battery current, such as the current being provided by each battery cell, is needed. However, the operating nature of vehicle batteries results in a very large range of operating currents. For example, a battery may provide 1000 Amps when starting the vehicle’s engine, provide 30 Amps during operation once the engine is running but draw just a few milliamps when idle. Thus, the measurement range required over the entire operating range of the battery ranges from a few milliamps to 1000 Amps and more. While techniques exist for measuring battery current, these existing approaches do not provide the level of accuracy desired across the entire operating range of the battery. The result is that measurements may meet or exceed an accuracy or fidelity threshold for some values of the current range, but not for all values, thereby lacking measurement accuracy throughout the entire range. SUMMARY

[0008] Some embodiments advantageously provide a method and system for current monitoring in batteries that allows for a consistent high degree of accuracy and / or fidelity (as compared with known solutions) across the entire current operating range of the battery.

[0009] The devices and methods described herein provide arrangements under which a higher value measurement shunt is used in conjunction with a lower value measurement shunt to increase fidelity, reduce dynamic range and increase signal-to-noise ratio (SNR) for lower current measurements to provide a more accurate measurement in the lower current ranges as compared with a single shunt used to measure current across the entire current range of the battery.

[0010] This can be done on the high current side or the low current side and accomplished in one embodiment using a metal-oxide-semiconductor field-effect transistor (MOSFET) switch. In some embodiments the MOSFET switch may be a secondary MOSFET switch that is already used for battery management as a secondary MOSFET switch used to diagnose the health and operational ability of the primary or main MOSFET switch. As a result, highly accurate current measurements can be made across the entire current operating range of the battery to achieve increased State of Charge (SoC) accuracy, meet higher Automotive Safety Integrity Levels (ASILs), increase vehicle controllability monitoring of vehicle loads as compared with existing solutions, and in a manner that is more cost effective than existing solutions.

[0011] According to one aspect, a battery management system (BMS) associated with a battery is described. The battery includes one or more battery cells, and the BMS includes a first shunt and a second shunt electrically coupled to the one or more battery cells. The first shunt has a first shunt resistance value for measuring a current within an upper subrange of a range of current. The second shunt has a second shunt resistance value for measuring the current within a lower subrange of the range of current. The BMS is configured to determine a current measurement mode for measuring the current associated with the battery using one or both of the first shunt and the second shunt. The current measurement mode is determined based on one or more parameters. The BMS is further configured to measure the current based on the current measurement mode and perform one or more actions based on one or both of the current measurement mode and the measured current.

[0012] In some embodiments, determining the current measurement mode may include selecting one or both of the first shunt and the second shunt based on the one or more parameters to measure the current. The current measurement mode may include a first current measurement mode to measure the current using the selected first shunt and a second current measurement mode to measure the current using the selected second shunt.

[0013] In some other embodiments, the BMS further includes a switch. The switch is electrically coupled to the second shunt and a second battery terminal different from a first battery terminal.

[0014] In some embodiments, the first shunt is electrically coupled to the one or more battery cells, the second shunt is electrically coupled to the one or more battery cells, and the BMS is further configured to energize, based on the one or more parameters, the switch to allow the current to flow from the second battery terminal through the switch and the second shunt to the one or more battery cells, and measure the current using the first shunt or the second shunt when the switch is energized.

[0015] In some other embodiments, the BMS is further configured to determine a BMS function based on the one or more parameters. The energizing of the switch being further based on the BMS function. The BMS function is associated with battery output, a battery operating mode, a predetermined battery load.

[0016] In some embodiments, the BMS includes a main relay and a secondary relay. The secondary relay includes the second shunt. The BMS is further configured to cause the main relay to enter a relay sleep mode, measure the current using the second shunt in the secondary relay, perform a relay diagnosis of the main relay based on the measured current.

[0017] In some other embodiments, the one or more parameters include one or both of the current and a vehicle operating mode.

[0018] In some embodiments, the one or more actions includes transmitting a first indication indicating the measured current, transmitting a second indication indicating the one or more parameters, and selecting a BMS operating mode.

[0019] According to another aspect, a battery comprising a battery management system (BMS) and one or more battery cells is described. The BMS includes a first shunt and a second shunt electrically coupled to the one or more battery cells. The first shunt has a first shunt resistance value for measuring a current within an upper subrange of a range of current, and the second shunt has a second shunt resistance value for measuring the current within a lower subrange of the range of current. The BMS is configured to determine a current measurement mode for measuring the current associated with the battery using one or both of the first shunt and the second shunt. The current measurement mode is determined based on one or more parameters. The BMS is configured to measure the current based on the current measurement mode and perform one or more actions based on one or both of the current measurement mode and the measured current.

[0020] According to one aspect, a system is described. The system includes a vehicle and a battery positionable within the vehicle. The vehicle includes a vehicle control system, and the BMS includes a first shunt and a second shunt electrically coupled to the one or more battery cells. The first shunt has a first shunt resistance value for measuring a current within an upper subrange of a range of current, and the second shunt has a second shunt resistance value for measuring the current within a lower subrange of the range of current. The BMS is configured to determine a current measurement mode for measuring the current associated with the battery using one or both of the first shunt and the second shunt. The current measurement mode is determined based on one or more parameters. The BMS is configured to measure the current based on the current measurement mode and cause transmission of a first indication to the vehicle control system, the first indication indicating the measured current.

[0021] In some embodiments, the BMS is further configured to cause transmission of a second indication to the vehicle control system, and the second indication indicates the one or more parameters.

[0022] In some other embodiments, one or both of the first indication and the second indication causes the vehicle control system to perform a control action.

[0023] In some embodiments, the vehicle control system includes one or more electronic control units (ECUs), and the control action includes one or more of performing an ECU diagnosis, resetting at least one ECU of the one or more ECUs, powered down at least one ECU of the one or more ECUs, power cycling at least one ECU of the one or more ECUs, and reconfiguring at least one ECU of the one or more ECUs.

[0024] According to one aspect, a method implemented in a battery management system (BMS) associated with a battery including one or more battery cells is described. The BMS includes a first shunt and a second shunt electrically coupled to the one or more battery cells. The first shunt has a first shunt resistance value for measuring a current within an upper subrange of a range of current, and the second shunt has a second shunt resistance value for measuring the current within a lower subrange of the range of current. The method includes determining a current measurement mode for measuring the current associated with the battery using one or both of the first shunt and the second shunt. The current measurement mode is determined based on one or more parameters. The method also includes measuring the current based on the current measurement mode and performing one or more actions based on one or both of the current measurement mode and the measured current.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS

[0026] A more complete understanding of embodiments described herein, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

[0027] FIG. 1 is a block diagram of an example system including a vehicle and battery constructed in accordance with the principles of present disclosure;

[0028] FIG. 2 is a block diagram of an example battery management system constructed in accordance with the principles of present disclosure;

[0029] FIG. 3 is a block diagram of a battery current monitoring system constructed in accordance with the principles of present disclosure;

[0030] FIG. 4 is a block diagram of another battery current monitoring system constructed in accordance with the principles of present disclosure;

[0031] FIG. 5 is a block diagram of an example relay with integrated current monitoring constructed in accordance with the principles of present disclosure; and

[0032] FIG. 6 is a flowchart of an example method in a battery management system in accordance with the principles of present disclosure.

[0033] DETAILED DESCRIPTION

[0034] Before describing in detail exemplary embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to current monitoring in batteries. In one or more embodiments, a current measuring mode is determined, where the current measurement mode may include selecting a first or second shunt to use for measuring a current associated with a battery, vehicle, etc., e.g., such that the selected shunt provides an accurate reading of current. Accordingly, the system and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and / or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0035] As used herein, high side refers to high current side and low side refers to low current side of the measurement range. The high side refers to greater current than the low side. By way of example, the low side may be used to provide measurements of up to 30 Amps, while the high side may be used from the range beyond the low side to the maximum operating current of the battery, e.g., 1000 Amps.

[0036] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0037] In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication.

[0038] In some embodiments, the term “range” is used and may refer to a plurality of values which may be arranged in increasing order such as from a minimum value to a maximum value, although the plurality of values may be arranged in any other order. For example, a range may include a current range, e.g., from 0 Amps (A) to 30A. A range may include multiple subranges such that each subrange includes a set of values of the plurality of values. For example, a first subrange of a range from 0A-30A may include values from 0A to 15A, while a second subrange may include values greater than 15A to 30A. In some embodiments, the second subrange that includes values that are greater than the values of the first subrange may be referred to as an upper subrange, while the first subrange may be referred to as a lower subrange.

[0039] In some embodiments, the general description elements in the form of “one of A and B” corresponds to A or B. In some embodiments, at least one of A and B corresponds to A, B or AB, or to one or more of A and B. In some embodiments, at least one of A, B and C corresponds to one or more of A, B and C, and / or A, B, C or a combination thereof.

[0040] As discussed below in detail, the battery current monitoring system described herein reduces noise error sources in the measurement system (as compared with known arrangements), enabling measurement detection and prediction for critical safety functions to ensure that the battery can deliver proper power to the vehicle when needed.

[0041] Referring now to the drawing figures in which like reference numbers refer to like elements, there is shown in FIG. 1, a system 1 comprising battery 10 and / or vehicle 11. Battery 10 is constructed in accordance with the principles of the present disclosure. Battery 10 may be, by way of non-limiting example, a lead-acid battery such as an AGM battery. Battery 10 includes a housing 12 into which one or more cells 14 are positioned. The cells 14 may be electrically interconnected (not shown in the FIGS), such as via an electrically conductive bus bar system which electrically interconnects the cells 14 in an electrically serial, electrically parallel or combination of electrically serial and parallel manner, depending on the intended voltage and current requirements. Arrangements are not limited to lead-acid batteries. It is contemplated that other battery technologies may be implemented such as Lithium-Ion. Thus, although the disclosure focuses on lead-acid technology, it is understood that this is for ease of explanation and understanding.

[0042] A battery monitoring system (BMS) 16 may be included. In some embodiments, the BMS may measure certain battery parameters, e.g., voltage, temperature, pressure, power, current, etc., and provide the data to an external system. BMS 16 may include a monitoring connector 18 that allows for an external connection to the vehicle’s data bus, or to some other communication device. The monitoring connector 18 can, in some embodiments, be integrated with the housing 12, such as in a cover 20 of the housing 12. Battery 10 also includes terminals, such as a negative terminal 22a and a positive terminal 22b (collectively referred to as terminals 22) to provide the contact points for electrical connection of the battery 10 to the vehicle to provide the auxiliary power to the vehicle. Terminals 22 are arranged to protrude through housing 12, such as protruding through cover 20. Terminals 22 may be electrically connected to the bus bars inside housing 12 and / or directly connected to the cells 14 (not shown in the FIGS). In some embodiments, housing 12 includes one or more vent holes to allow venting from one or more of the cells 14. Battery 10 also includes current monitoring system 24 arranged to monitor battery current levels as described herein. Current monitoring system 24 can be implemented as part of BMS 16 or separate from BMS 16. Although shown as part of battery 10, it is understood that current monitoring system 24 can be implemented separately from battery 10 and interconnected to battery 10 via electrical connections.

[0043] Battery 10 can be arranged to provide many power capacities and physical sizes, and to operate under various parameters and parameter ranges. It is also noted that implementations of battery 10 can be scaled to provide various capacities. Power capacity scaling can be accomplished, for example, by using higher or lower power capacity cells 14 in the housing 12, and / or by using fewer or more cells 14 in the housing 12. In some embodiments, battery 10 may be incorporated as part of a vehicle such as an electric vehicle (EV) or another type of vehicle where battery power is needed. Other electrical parameters of the battery 10 can be adjusted / accommodated by using cells 14 that may cumulatively have the desired operational characteristics, e.g., voltage, charging capacity / rate, discharge rate, etc. Thermal properties can be managed based on cell 14 characteristics, the use of heat sinks and / or thermal energy discharge plates, etc., within or external to the housing 12.

[0044] Battery 10 may be associated with vehicle 11. For example, battery 10 may be arranged to power systems of vehicle 11 such as vehicle control system 13 and / or any other vehicle system and / or component. In another example, vehicle 11 comprises vehicle control system 13 which comprises one or more electronic control units (ECUs) 15 (collectively referred to as ECU 15). Vehicle 11 and / or vehicle control system 13 and / or ECUs 15 may be configured to communicate with battery 10 and any components of battery 10 such as BMS 16. For example, BMS 16 may transmit signals to and / or receive signals from vehicle 11 and / or vehicle control system 13. In some embodiments, BMS 16 and / or any other component of battery 10 (e.g., current monitoring system 24) may be electrically coupled to vehicle 11 and / or vehicle control system 13 and / or ECU 15 via monitoring connector 18. In some other embodiments, BMS 16 and / or any other component of battery 10 is connected to vehicle 11 and vehicle control system 13 and / or ECU 15 via a wired / wireless communication link.

[0045] In some embodiments, vehicle control system 13 and / or ECU 15 are configured to perform one or more control functions associated with vehicle 11 and may draw current from battery 10 to perform the control functions or any other functions. Further, ECU 15 may be configured to operate in one or more operation modes where each mode is expected to draw a predetermined current or current in a predetermined range and / or consume a predetermined power or a power within a predetermined power range. For example, an ECU 15 may draw a current that is within a current range and within a first current subrange (e.g., low current subrange) when the ECU 15 is operating in a first operation mode (e.g., such as in sleep mode). The ECU 15 may draw a current that is within the current range and within a second current subrange (e.g., high current range) when the ECU 15 is operating in a second operation mode (e.g., such as in active mode). BMS 16 may be configured to determine the current draw of vehicle 11 and / or vehicle control system 13 and / or ECU 15 and make one or more other determinations and / or perform actions. For example, BMS 16 may determine the current draw of an ECU 15 and determine that although the ECU 15 is expected to be in a sleep mode, the current draw of the ECU 15 does not correspond to a sleep mode and thus may be malfunctioning. The BMS 16 may transmit indications and / or data and / or information associated with such determinations to vehicle 11 and / or vehicle control system 13 and / or ECU 15, e.g., so that an action associated with the malfunctioning ECU 15 can be performed such as resetting ECU 15, powering down ECU 15, disconnecting loads or other circuit components from ECU 15, etc.

[0046] Although a vehicle 11 is shown, any other system may be powered by battery 10 and may be arranged to perform similar functions as vehicle 11, and BMS 16 may perform any of the functions described herein in connection with any other system.

[0047] As shown in FIG. 2, the BMS 16 comprises hardware (HW) 42 including processing circuitry 48, which may include a processing unit (e.g., processor) 52 and memory 50, to perform one or more functions described herein. BMS 16 may include communication unit(s) 46 (e.g., communication interfaces) 46 to communicate with sensors that monitor the cells 14, and other operational parameters of the battery 10, and / or communicate with external elements of system 1 or any other system. For example, communication interface 46 may also be configured to communicate with vehicle 11 and / or vehicle control system 13 and / or ECU 15 (shown in FIG. 1). More specifically, communication interface 46 may be configured to transmit and / or receive one or more signals associated with a determination (by BMS 16) of a parameter (e.g., current draw) associated with battery 10 and / or vehicle 11 and / or vehicle control system 13 and / or ECU 15 and / or any other component of system 1. The signals may comprise indications and / or data and / or information usable to determine battery parameters, vehicle parameters, vehicle control system parameters, ECU parameters, etc. Any of the parameters may include current draw, power, ranges, subranges, state information, state of charge, state of function, commands, etc. For example, the signals may be used by BMS 16 or any component of BMS described herein to perform one or more functions. Similarly, the signals may be used by vehicle 11 and / or vehicle control system 13 and / or ECU 15 or any component of vehicle 11 to perform one or more functions. BMS 16 may be operated using one or more BMS operating modes such as sleep mode, energy saving mode, active mode, diagnostics mode, a mode to manage high battery loads, a mode to manage low battery loads, a mode to manage currents in a lower subrange, a mode to manage current in an upper subrange, etc.

[0048] In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry may comprise integrated circuitry for processing and / or control, e.g., one or more processors and / or processor cores and / or FPGAs (Field Programmable Gate Array) and / or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 52 may be configured to access (e.g., write to and / or read from) memory, which may comprise any kind of volatile and / or nonvolatile memory, e.g., cache and / or buffer memory and / or RAM (Random Access Memory) and / or ROM (Read-Only Memory) and / or optical memory and / or EPROM (Erasable Programmable Read- Only Memory).

[0049] Processing circuitry 48 may be configured to control any of the methods and / or processes described herein and / or to cause such methods, and / or processes to be performed, e.g., by BMS 16. Processor 52 corresponds to one or more processors 52 for performing BMS 16 functions described herein. The BMS 16 includes memory 50 that is configured to store data, programmatic software code and / or other information described herein. In some embodiments, the software (SW) 40 and / or the BMS application 44 may include instructions that, when executed by the processor 52 and / or processing circuitry 48, causes the processor 52 and / or processing circuitry 48 to perform the processes described herein with respect to BMS 16. The instructions may be software associated with the BMS 16.

[0050] The processing circuitry 48 of the BMS 16 may include a monitoring unit 54 configured to perform one or more BMS 16 functions described herein, including functions related to battery current monitoring. Additional functions that may be performed by the BMS 16 are as follows. In some embodiments, BMS 16 may include one or more components such as current monitoring system 24 which may include one or more circuit elements and / or be configured to perform monitoring of parameters such as monitoring current. However, current monitoring system 24 may not be in BMS 16 and / or may be remote and / or standalone and / or in communication with BMS 16.

[0051] FIG. 3 is a block diagram of an example battery current monitoring system 24 constructed in accordance with the principles of present disclosure. Battery current monitoring system 24 may include one or more of current measurement unit 58, main relay 60, secondary relay 62, and shunts 64, 66. Main relay 60 may be electrically coupled to cells 14 (e.g., to positive side of cells 14) and also be electrically coupled to terminal 22b (e.g., positive terminal) of battery 10. Further, secondary relay 62 may be electrically coupled to shunt 66 and to terminal 22b, while shunt 66 is also electrically coupled to cells 14 (e.g., positive side of cells 14). Shunt 64 may be electrically coupled to cells 14 (e.g., negative side of cells 14) and to terminal 22a (e.g., negative terminal) of battery 10. Current measurement unit may be electrically coupled to shunt 64 and / or shunt 66. In a nonlimiting example, shunt 64 is a low ohmic shunt, and shunt 66 is a high ohmic shunt.

[0052] In some embodiments, main relay 60 is configured to act as connect / disconnect between the battery 10 and a load on terminals 22 (e.g., the vehicle bus or power net). More specifically, main relay 60 may open / close the electrical path that includes main relay 60 between terminal 22b and cells 14. Secondary relay 62 is configured to enable / disable a connection to the load coupled to terminals 22 (e.g., vehicle). The connection may be enabled while BMS 16 performs diagnosis functions on the main relay 60. That is, secondary relay 62 may provide a switching mechanism that provides an electrical path from cells 14 to terminal 22b, when the electrical path that includes main relay 60 is open or not available. Further, current measurement unit 54 may be configured to perform functions related to battery current monitoring such as measuring the current through shunt 64 and / or shunt 66. In a nonlimiting example, current monitoring unit 58 may measure the current through shunt 66 such as when main relay 60 is being diagnosed by BMS 16. In other words, some embodiments provide a dual function (e.g., diagnosis and current measurement). At least secondary relay 62 allows switching shunt 66 to provide greater resolution and fidelity of the current such as when the battery 10 is supplying power (associated with a lower current range / subrange) to the vehicle 11, vehicle control system 13, ECU 15, etc.

[0053] In some other embodiments, shunt 64 and / or current measurement unit 58 may be used to measure the full range (or a subrange) of current of battery 10. For example, shunt 64 (e.g., low ohmic shunt) may be always in use (i.e., current flowing through shunt 64). That is, the path where shunt 64 is located or shunt 64 is not required to be switched on or off, while the path where shunt 66 is located or shunt 66 may be switched on or off (e.g., via secondary relay 62) to measure current on the corresponding path such as when main relay 60 is disconnected or being diagnosed.

[0054] In some embodiments, the positive side and negative side of the cells 14 may be at different locations than those shown in FIG. 3.

[0055] FIG. 4 shows a block diagram of another example battery current monitoring system 24 constructed in accordance with the principles of present disclosure. Battery current monitoring system 24 may include one or more of power unit 56, current measurement unit 58, main relay 60, secondary relay 62, etc. Further, current monitoring system 24 may include one or more of each one of shunt 64 and shunt 66. Any of the components of current monitoring system 24 may be in communication with (e.g., electrically coupled to) another battery component such as battery cells 14 and / or BMS function 68.

[0056] For example, shunt 64 may be electrically coupled to battery cells 14, BMS function 68, main relay 60, secondary relay 62, etc. Shunt 64 may be used by BMS 16 to measure current passing through the component to which it is coupled or through the circuit branch on which shunt 64 is located. Current measurement unit 58 may be in communication with shunt 64 and be configured to measure such current. Secondary relay 62 may include 66 used to measure the current through the relay based on the voltage drop across the shunt measured by current measurement unit 58.

[0057] In some embodiments, power unit 56 is electrically coupled to battery cells 14. In some other embodiment, power unit56 is arranged to provide isolated power to current measurement unit 58, e.g., by using the same isolated ground as current measurement unit 58. However, the embodiments of the present disclosure are not limited as such and the high side current measurement (i.e., associated with shunt 66) may not require an isolated power supply such as power unit 56. Further, power unit 56 can be used to convert the cell battery voltage to a voltage suitable for use by current measurement unit 58. In some embodiments, current measurement unit 58 is an analog to digital converter (ADC). The ADC can be a multichannel ADC, thereby allowing current measurement unit 58 to sample and determine separate current values for each of main relay 60 and secondary relay 62. Current measurement unit 58 outputs the digital current values to a processor for further evaluation and current determination, such as the processing circuitry 48 of BMS 16.

[0058] Main relay 60 and secondary relay 62 may be electrically connected to one or more battery cells 14 as well as BMS function 68. BMS function 68 can be implemented by BMS 16 or can be performed as a BMS-like function in a separate device such as a cell monitoring device (CMD) where the CMD does not perform all functions of a BMS and only performs some cell monitoring functions. BMS functions may include any tasks and / or steps and / or processes performed by the BMS 16. As discussed below in detail with reference to FIG. 4, the current from battery cells 14 may be (directly / indirectly) passed through shunts 64 and 66.

[0059] As discussed below in detail, using different resistor values in shunts 64 and 66 allows current to be accurately measured over the entire operating current range of battery 10 (e.g. where shunt 64 is configured for one subrange of the entire operating current range, and shunt is configured for another subrange of the entire operating current range). The overall operation of main relay 60, secondary relay 62, shunt 64, and shunt 66 may be controlled by BMS function 68. In some embodiments such as arrangements where BMS function 68 is implemented by a BMS 16 (as opposed to a stand-alone CMD that does not include all BMS circuitry / functionality), BMS function 68 is electrically connected to battery cells 14 (shown in FIG. 3 as a dashed line connection). In some embodiments, main relay 60 and secondary relay 62 are solid state relays (SSRs) in which the switch portions of the relays are semiconductors such as Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). The power outputs of main relay 60 and secondary relay 62 are electrically coupled to the positive battery terminal 22b. The electrical grounds of main relay 60, secondary relay 62 and BMS function 68 are electrically coupled to negative battery terminal 22a. In some embodiments, main relay 60 and / or shunt 64 can be used to measure high side current (i.e., current within a second subrange or upper subrange) and secondary relay 62 can be used to measure low side current (i.e., current within a first subrange or lower subrange). It is understood that implementations are not limited to this arrangement and that main relay 60 can be used to measure low side current and secondary relay 62 can be used to measure high side current. In some arrangements, secondary relay 62 may also be used to evaluate the operating performance of main relay 60 such as to confirm that main relay is properly operating as a relay.

[0060] FIG. 5 is a block diagram of an example relay with integrated current monitoring constructed in accordance with the principles of present disclosure. For ease of understanding, FIG. 5 shows only a single relay as the general construction of secondary relay 62 may be the same other than the values of its components such as resistance.

[0061] Relay 62 may include switch 70 in the electrical path from battery cells 14 to the positive battery terminal 22b (or negative terminal 22a). Switch 70 may be a MOSFET having one or more gates controlled by relay controller 72, based on instructions received from BMS function 68. Controller 72 may be comprised in BMS 16 and / or may refer to any of its components such as processor 52, monitoring unit 54, etc. In some embodiments, when switch 70 is closed, current flows through shunt 66 to battery terminal 22b (or if connected to another terminal, from the battery terminal). Also, current measurement unit 58 can measure the voltage drop across shunt 66. Processing circuitry 48 receives the measurements taken from secondary relay 62 and can determine, e.g., based on programming logic / instructions, which value to use to determine current and / or current consumption (e.g., by a vehicle 11, vehicle control system 13, ECU 15, etc.).

[0062] In some embodiments, the values of the resistors associated with shunts 64 and 66 can be different on the high side and low side (i.e., upper subrange and lower subrange). In a nonlimiting example, the high side shunt 64 (shown in FIG. 3) resistor may have a value in the micro-ohm range, while the low side shunt 66 resistor may have a value in the milli-ohm range. The effect is that the higher value shunt resistor is effectively “switched” into the measurement circuit for lower current measurements, i.e., currents at the lower operating range of battery 10. This arrangement allows for a more precise measurement on the low side than would be possible using the same relay and shunt for both high and low current measurements. The larger voltage drop across the low side shunt 66 resistor as compared with using the smaller value high side shunt 64 resistor provides better SNR on the low side than trying to measure low current values using the resistor used to measure the high side current. This arrangement may allow a 50 or more times improvement in current measurement accuracy than known arrangements.

[0063] Of note, although FIG. 5 shows a single shunt 66 in relay 62, it is understood that multiple resistors can be used to form each shunt 66 (or shunt 64) such as by placing the resistors in an electrically parallel circuit arrangement. Thus, the specific values of shunts 64 and 66 can be created using multiple resistors. Similarly, although FIG. 4 shows a single switch 70 in relay 62, it us understood that multiple switches, e.g., multiple MOSFETs, can be used in relay 62 depending on design needs, e.g., current capacity requirements.

[0064] Although FIGS. 2 and 3 show an embodiment where the current is measured along a predetermined signal path, it is also contemplated that the current be measured by placing shunts 64, 66 along another path and by measuring the resultant current. It is also contemplated that multiple shunt 64 can be used to measure high side current and / or shunt 66 can be used to measure low side current. Further, although FIG.4 shows an arrangement that uses power unit 56, other embodiments can be implemented without power unit 56. For example, the current measurements taken through shunts 64 and 66 can be fed to front end operating amplifiers (op-amps), and then fed to an ADC. Such an arrangement would boost the signal values fed to the ADC, thereby reducing the need for isolated power while still maintaining accuracy and an acceptable SNR.

[0065] In some embodiments, shunts 64, 66 may be located low side (e.g., on the negative side of the cells 14 where shunt 64 is located on FIG. 3) and switch shunt 66 such as to measure current as described with respect to shunt 66.

[0066] In some embodiments, shunts 64, 66 may be used to measure (e.g. via current measurement unit 58 and / or BMS 16) current within an entire range of current (or one or more subranges within the entire range). For example, shunt 66 may be arranged for measuring a lower subrange (e.g., OA to first current value), and shunt 64 an upper subrange (e.g., first current value to maximum current value) or the entire range. In some other embodiments, BMS 16 may be configured to switch any shunt such as shunt 66 on (by enabling switch 70) to measure the current in a corresponding subrange / range based on one or more parameter or information such as the state of a load such as an ECU 15. For example, current measurement unit 58 may be arranged to measure the current that passes through shunt 64 (e.g., based on the voltage drop and resistance value of shunt 64). This current may be in the upper subrange (or the entire range), and the resistance value of the shunt 64 may be preselected specifically to obtain accurate current readings in the upper subrange or range, e.g., that meet or exceed a fidelity threshold. Further, controller 72 may trigger switch 70 (e.g., MOSFET) to allow current to flow across switch 70, thereby allowing current to flow from the positive battery terminal 22b through switch 70b and shunt 66 to battery cells 14. Current measurement unit 58 may be arranged to measure the current that passes through shunt 66 (e.g., based on the voltage drop and resistance value of shunt 66). This current may be in the lower subrange (or any other subrange / range) and the resistance value of the shunt 66 may be preselected specifically to obtain accurate current readings in the lower subrange e.g., that meet or exceed another fidelity threshold.

[0067] In some embodiments, when one shunt is switched on, the other shunt is switched off. That is, current may be allowed to pass via the corresponding shunt 64, 66 based on one or more parameters, e.g., the subrange for which current is desired to be measured. Thus, BMS 16 at least via components shown in FIGS. 3-5 may be configured to assign a shunt 64, 66 to a subrange of current and switch on or off the flow of current to a corresponding shunt such as shunt 66 based on or more parameters. Put differently, current measurement unit 58 can measure current on multiple subranges within an operating current range using one or more shunts 64, 66 that provide accurate readings for their corresponding subranges. In some embodiments, BMS 16 may obtain information from vehicle 11, vehicle control system 13, and / or ECU 15 and determine based on the obtained information that a current to be measured is expected to be within a first subrange. BMS 16 may select the shunt 64, 66 that corresponds to the subrange and / or trigger switch 70 corresponding to shunt 66, causing current to flow through the corresponding shunt 66and measure (e.g., via current measurement unit 58) the current. The BMS 16 may transmit the value of the measured current (e.g., comprised in signaling, an indication, a report, etc.) to vehicle 11, vehicle control system 13, and / or ECU 15. The transmitted value may trigger vehicle 11, vehicle control system 13, and / or ECU 15 to perform an action which may be associated with the management of vehicle 11, vehicle control system 13, and / or ECU 15. For example, if the current value for an ECU 15 is outside a predetermined range (e.g., current range for sleep mode of the ECU 15), they ECU 15 may be malfunctioning and may be diagnosed, reset, powered down, power cycled, reconfigured, etc.

[0068] In some embodiments, BMS 16 may perform a diagnosis of main relay 60 by turning off main relay 60, turning secondary relay 62 (and / or shunt 66) on to measure current. Turning main relay 60 off and turning secondary relay 62 on may increase the accuracy of the current reading than if main relay 60 is left on. As shunt 66 may measure the current that goes through the secondary relay 62 when operating in a low current mode, the current within the lower subrange is driven to go through the secondary relay 62 and / or shunt 66.

[0069] In some embodiments, the BMS 16 can determine a period of time for which switch 70 may be turned on / off (based on a predetermined configuration associated with BMS 16 and / or vehicle 11 and / or vehicle control system 13 and / or ECU 15). For example, a sleep mode may be associated with vehicle 11 and / or vehicle control system 13 and / or ECU 15 and may have a corresponding sleep time window. The sleep time window may be used to turn switch 70 on and use the shunt 66 to measure current that is associated with a sleep mode (e.g., current in the lower subrange). Similarly, an active mode may be associated with vehicle 11 and / or vehicle control system 13 and / or ECU 15 and may have a corresponding active time window. The active time window may be used to measure current (e.g., via shunt 64) that is associated with the active mode (e.g., current in the upper subrange). Any other combinations of shunts 64, 66 and modes may be used.

[0070] Further, BMS 16 may obtain information or an indication indicating what mode vehicle 11 and / or vehicle control system 13 and / or ECU 15 is in or will be in within a predetermined period of time. The information and / or indication may be used by BMS 16 to determine when to use shunts 64, 66 to measure current. BMS 16 may also read a state or status of a vehicle system and / or battery and determine that the current of the lower / upper subrange is to be measured. The measured current may be used to further determine a parameter such as state of charge of battery 10 as the measured current has greater fidelity and less measurement errors than using conventional methods.

[0071] In some other embodiments, BMS 16 and / or vehicle 11 and / or vehicle control system 13 and / or ECU 15 may be used for vehicle controllability monitoring. For example, measured current may be used to determine when vehicle 11 and / or vehicle control system 13 and / or ECU 15 is going to enter a sleep mode. For example, different ECUs 15 in the vehicle 11 may turn off or enter a sleep mode at different times. Each ECU 15 may have a predetermined characteristic current drop such as changes of current within a unit of time. The predetermined characteristic current drops and the measured current may be used to determine when the vehicle 11 and / or vehicle control system 13 and / or ECU 15 is shutting down or entering the sleep mode. BMS 16 may use this information to perform one or more actions such as changing a battery function (e.g., remove power to the ECU 15).

[0072] FIG. 6 shows an example method implemented in a BMS 16. One or more blocks may be performed by any of the components of BMS 16 such as BMS application 44, communication interface 46, processing circuitry 48, memory 50, processor 52, monitoring unit 54, current monitoring system 24, etc. The BMS 16 is associated with a battery 10 that includes one or more battery cells 14. The BMS 16 includes a first shunt 64 and a second shunt 66 electrically coupled to the one or more battery cells 14. The first shunt has a first shunt resistance value for measuring a current within an upper subrange of a range of current. The second shunt 66 has a second shunt resistance value for measuring the current within a lower subrange of the range of current. BMS 16 is configured to determine (Block S100) a current measurement mode for measuring the current associated with the battery 10 using one or both of the first shunt 64 and the second shunt 66, where the current measurement mode is determined based on one or more parameters, measure (Block S102) the current based on the current measurement mode, and perform (Block S104) one or more actions based on one or both of the current measurement mode and the measured current.

[0073] In some embodiments, determining the current measurement mode may include selecting one or both of the first shunt and the second shunt based on the one or more parameters to measure the current. The current measurement mode may include a first current measurement mode to measure the current using the selected first shunt and a second current measurement mode to measure the current using the selected second shunt. In some other embodiments, the BMS 16 further includes a switch 70. The switch 70 is electrically coupled to the second shunt 66 and a second battery terminal 22.

[0074] In some embodiments, the first shunt 64 is electrically coupled to the one or more battery cells 14, the second shunt 66 is electrically coupled to the one or more battery cells 14, and the BMS 16 is further configured to energize based on the one or more parameters, the switch 70 to allow the current to flow from the second battery terminal 22 through the switch 70 and the second shunt 66 to the one or more battery cells 14, and measure the current using the first shunt 64 or the second shunt 66 when the second switch 70 is energized.

[0075] In some other embodiments, the BMS 16 is further configured to determine a BMS function 68 based on the one or more parameters, the energizing of the switch 70 being further based on the BMS function 68, the BMS function 68 being associated with battery output, a battery operating mode, a predetermined battery load.

[0076] In some embodiments, the BMS 16 comprises a main relay 60 and a secondary relay 62. The secondary relay 62 includes the second shunt 66, and the BMS 16 is further configured to cause the main relay 60 to enter a relay sleep mode, measure the current using the second shunt 66 in the secondary relay 62, perform a relay diagnosis of the main relay 60 based on the measured current.

[0077] In some other embodiments, the one or more parameters include the current, the first shunt resistance value, the upper subrange, the second shunt resistance value, the lower subrange, the range of current, and a battery characteristic (e.g., a battery specification value).

[0078] In some embodiments, the one or more actions includes transmitting a first indication indicating the measured current, transmitting a second indication indicating the one or more parameters, and selecting a BMS operating mode.

[0079] It will be appreciated by persons skilled in the art that the present embodiments are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings and following claims.

Claims

What is claimed:

1. A battery management system, BMS, (16) associated with a battery (10) comprising one or more battery cells (14), the BMS (16) comprising: a first shunt (64) and a second shunt (66) electrically coupled to the one or more battery cells (14), the first shunt (64) having a first shunt resistance value for measuring a current within an upper subrange of a range of current, the second shunt (66) having a second shunt resistance value for measuring the current within a lower subrange of the range of current; the BMS (16) being configured to: determine a current measurement mode for measuring the current associated with the battery (10) using one or both of the first shunt (64) and the second shunt (66), the current measurement mode being determined based on one or more parameters; measure the current based on the current measurement mode; and perform one or more actions based on one or both of the current measurement mode and the measured current.

2. The BMS (16) of Claim 1, wherein one or both of: determining the current measurement mode includes selecting one or both of the first shunt (64) and the second shunt (66) based on the one or more parameters to measure the current; and the current measurement mode includes a first current measurement mode to measure the current using the selected first shunt (64) and a second current measurement mode to measure the current using the selected second shunt (66).

3. The BMS (16) of any one of Claims 1 and 2, wherein the BMS (16) further includes a switch (70), the switch (70) being electrically coupled to the second shunt (66) and a second battery terminal (22) different from a first battery terminal (22).

4. The BMS (16) of Claim 3, wherein the first shunt (64) is electrically coupled to the one or more battery cells (14), the second shunt (66) is electrically coupled to the one or more battery cells (14), and the BMS (16) is further configured to:energize, based on the one or more parameters, the switch (70) to allow the current to flow from the second battery terminal (22) through the switch (70) and the second shunt (66) to the one or more battery cells (14); and measure the current using: the first shunt (64); or the second shunt (66) when the switch (70) is energized.

5. The BMS (16) of Claim 4, wherein the BMS (16) is further configured to: determine a BMS function based on the one or more parameters, the energizing of the switch (70) being further based on the BMS function, the BMS function being associated with battery output, a battery operating mode, a predetermined battery load.

6. The BMS (16) of any one of Claims 1-5, wherein the BMS (16) comprises a main relay (60) and a secondary relay (62), the secondary relay (62) comprising the second shunt (66), the BMS (16) being further configured to: cause the main relay (60) to enter a relay sleep mode; measure the current using the second shunt (66) in the secondary relay (62); and perform a relay diagnosis of the main relay (60) based on the measured current.

7. The BMS (16) of any one of Claims 1-6, wherein the one or parameters include one or both of the current and a vehicle operating mode.

8. The BMS (16) of any one of Claims 1-6, wherein the one or more actions includes: transmitting a first indication indicating the measured current; transmitting a second indication indicating the one or more parameters; and selecting a BMS operating mode.

9. A battery (10) comprising a battery management system, BMS, (16) and one or more battery cells (14), the BMS (16) comprising: a first shunt (64) and a second shunt (66) electrically coupled to the one or more battery cells (14), the first shunt (64) having a first shunt resistance value for measuring a current within an upper subrange of a range of current, the second shunt (66) having asecond shunt resistance value for measuring the current within a lower subrange of the range of current; the BMS (16) being configured to: determine a current measurement mode for measuring the current associated with the battery (10) using one or both of the first shunt (64) and the second shunt (66), the current measurement mode being determined based on one or more parameters; measure the current based on the current measurement mode; and perform one or more actions based on one or both of the current measurement mode and the measured current.

10. A system (1), the system (1) comprising a vehicle (11 )and a battery (10) positionable within the vehicle (11), the vehicle (l l)comprising a vehicle control system (13), the BMS (16) comprising: a first shunt (64) and a second shunt (66) electrically coupled to the one or more battery cells (14), the first shunt (64) having a first shunt resistance value for measuring a current within an upper subrange of a range of current, the second shunt (66) having a second shunt resistance value for measuring the current within a lower subrange of the range of current; the BMS (16) being configured to: determine a current measurement mode for measuring the current associated with the battery (10) using one or both of the first shunt (64) and the second shunt (66), the current measurement mode being determined based on one or more parameters; measure the current based on the current measurement mode; and cause transmission of a first indication to the vehicle control system (13), the first indication indicating the measured current.

11. The system (1) of Claim 10, wherein the BMS (16) is further configured to: cause transmission of a second indication to the vehicle control system (13), the second indication indicating the one or more parameters.

12. The system (1) of Claim 11, wherein one or both of the first indication and the second indication causes the vehicle control system (13) to perform a control action.

13. The system (1) of Claim 12, wherein the vehicle control system (13) comprises one or more electronic control units, ECUs, (15) and the control action includes one or more of: performing an ECU diagnosis; resetting at least one ECU (15) of the one or more ECUs (15); powered down at least one ECU (15) of the one or more ECUs (15); power cycling at least one ECU (15) of the one or more ECUs (15); and reconfiguring at least one ECU (15) of the one or more ECUs (15).

14. A method implemented in a battery management system, BMS (16), associated with a battery (10) comprising one or more battery cells (14), the BMS (16) comprising a first shunt (64) and a second shunt (66) electrically coupled to the one or more battery cells (14), the first shunt (64) having a first shunt resistance value for measuring a current within an upper subrange of a range of current, the second shunt (66) having a second shunt resistance value for measuring the current within a lower subrange of the range of current, the method comprising: determining (SI 00) a current measurement mode for measuring the current associated with the battery (10) using one or both of the first shunt (64) and the second shunt (66), the current measurement mode being determined based on one or more parameters; measuring (S102) the current based on the current measurement mode; and performing (SI 04) one or more actions based on one or both of the current measurement mode and the measured current.

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