Battery real-time internal short circuit detection

Abstract

The invention discloses battery real-time internal short circuit detection. A system may include a battery and a processor configured to continuously record a voltage and a current as a function of time. A time window may be determined based on the current as a function of time. During the time window, the accumulated charge may be substantially zero, and the accumulated absolute value of the charge may be substantially equal to the stored comparison value. The processor may calculate an energy loss of the battery and a charge loss rate of the battery over the time window. The processor may further determine whether there is an internal short circuit within the battery based on the charge loss rate and a predetermined threshold. In response to determining that the internal short circuit is present, the processor may generate an indication that the internal short circuit is present.

Description

Technical Field The present disclosure relates generally to the field of short circuit detection, and more particularly to real-time internal short circuit detection of a battery. Background Art Internal short circuits (ISC) may occur within lithium-ion battery cells due to the establishment of short-circuit pathways, which may be the result of the lithium-ion dendritic process. The dendritic process may be caused by manufacturing defects, deformation of the battery cell due to external forces, battery abuse (such as fast charging or overcharging), degradation over time, or a combination of each of these factors. ISC may lead to thermal runaway and even catastrophic failure, causing significant economic losses in transportation and other industries. Offline detection of ISC can include interrupting battery operation. For example, the system can be temporarily offline, and in some cases, the battery can be removed for testing. Therefore, these detection methods are not suitable for real-time detection, such as during vehicle operation. Temperature sensing can also provide an indication of ISC. However, the temperature criteria associated with the ISC condition are difficult to determine because the temperature increase may be caused by reasons other than ISC, such as high current conditions or external cooling of the battery. In addition, when ISC occurs, the temperature may rise rapidly. Therefore, temperature sensing is not a reliable method for early ISC detection. Internal resistance sensing within the battery can also be considered for detection of ISC conditions. For example, when ISC has been established, the internal resistance of the battery may become infinitely small. However, typical batteries have internal parameters such that the resistance calculated based on the voltage and current at the battery terminals may be inconsistent with the actual ISC establishment process. There may be other disadvantages. Summary of the invention Disclosed herein is a system and method for real-time ISC detection of a battery that overcomes at least one of the above-mentioned shortcomings. In one embodiment, a method includes determining a dynamic time window based on the law of conservation of charge, and then calculating the internal charge loss rate within the time window based on the law of conservation of energy. The internal charge loss rate can be compared with a given threshold to determine whether the battery ISC has occurred. In addition, the internal charge loss rate can be compared with the internal charge loss rate of the dynamic window previously acquired, thereby minimizing the impact of measurement errors. These operations can enable real-time detection of ISC without interrupting normal battery operation. As an additional benefit, common battery signals (e.g., voltage and current) can be used for detection, which can be measured at the battery terminals. Therefore, compared with other ISC detection methods, the disclosed method can be simple and easy to implement. In one embodiment, a system includes: a battery having a set of terminals; and one or more processing elements configured to continuously record a voltage as a function of time and a current as a function of time at the set of terminals. The one or more processing elements are further configured to determine a time window based on the current as a function of time. During the time window, the accumulated charge is substantially zero. In addition, during the time window, the accumulated absolute value of the charge is substantially equal to a stored comparison value. The one or more processing elements are also configured to calculate the energy loss of the battery within the time window, calculate the charge loss rate of the battery within the time window based at least in part on the energy loss of the battery within the time window, and determine whether there is an internal short circuit in the battery based on the charge loss rate and a predetermined threshold. In response to determining that there is an internal short circuit, the one or more processing elements are configured to generate an indication that there is an internal short circuit. In some embodiments, the one or more processing elements are configured to, in response to an indication of the presence of an internal short circuit, initiate a battery automatic shutdown operation associated with the battery, transfer a load to another battery, or both. In some embodiments, the one or more processing elements are configured to continuously and repeatedly determine an additional time window based on the current as a function of time, continuously and repeatedly calculate an additional energy loss of the battery within the additional time window, continuously and repeatedly calculate an additional charge loss rate of the battery within the additional time window, and continuously and repeatedly determine whether an internal short circuit exists based on the additional charge loss rate of the battery and a predetermined threshold. In some embodiments, one or more processing elements are configured to continuously update an average charge loss rate of the battery based on a predetermined number of most recently calculated additional charge loss rates. In some embodiments, the stored comparison value is a rated cell capacity value associated with the battery. In some embodiments, as part of calculating the energy loss of the battery within a time window, the one or more processing elements are configured to: calculate the amount of energy transferred at a set of terminals during the time window during charging of the battery, calculate the amount of energy transferred at a set of terminals during the time window during discharging of the battery, and calculate the internal resistance energy loss at a set of terminals during the time window based on a predetermined resistance of the battery. In some embodiments, the energy loss of the battery within the time window is substantially equal to the difference between the calculated amount of energy transferred during charging of the battery and the combination of the amount of energy transferred during discharging of the battery and the internal resistance energy loss. In some embodiments, the predetermined resistance of the battery is determined by manufacturer specifications or laboratory testing. In some embodiments, as part of calculating the charge loss rate of the battery within the time window, the one or more processing elements are configured to calculate the average battery potential during the time window. In some embodiments, the charge loss rate of the battery is substantially equal to the energy loss of the battery within the time window divided by the product of the average battery potential during the time window and the duration of the time window. In some embodiments, as part of determining whether there is an internal short circuit, the one or more processing elements are configured to: calculate the average charge loss rate of the battery based on a predetermined number of recently calculated charge loss rates, calculate the difference between the charge loss rate of the battery and the average charge loss rate of the battery, and determine whether the difference is greater than a predetermined threshold. In some embodiments, the battery and the one or more processing elements are incorporated into the aircraft. In one embodiment, a system includes a processor and a memory, wherein the memory stores instructions that, when executed by the processor, cause the processor to continuously record voltage as a function of time and current as a function of time at a set of terminals of a battery. The instructions further cause the processor to select a start time T of a time window that substantially satisfies the following equation start and the end time of the time window T stop , the time window is determined based on the current as a function of time: and where i is the current as a function of time, and where C W is a stored comparison value. The instructions further cause the processor to calculate the energy loss of the battery within the time window, calculate a charge loss rate of the battery within the time window based at least in part on the energy loss of the battery within the time window, and determine whether there is an internal short circuit within the battery based on the charge loss rate of the battery and a predetermined threshold. In response to determining that an internal short circuit exists, the instructions cause the processor to generate an indication that an internal short circuit exists. In some embodiments, the energy loss of the battery within the time window substantially satisfies the following equation: Where E2 is the calculated energy loss of the battery, v is the voltage as a function of time, and R is the predetermined resistance of the battery. In some embodiments, the charge loss rate of the battery within the time window substantially satisfies the following equation: Where CLR is the charge loss rate of the battery within the time window, E2 is the calculated energy loss of the battery, v is the voltage as a function of time, and R is the predetermined resistance of the battery. In one embodiment, a method includes continuously recording a voltage as a function of time and a current as a function of time at a set of terminals of a battery. The method further includes determining a time window based on the current as a function of time, wherein during the time window, the accumulated charge is substantially zero, and wherein during the time window, the accumulated absolute value of the charge is substantially equal to a stored comparison value. The method also includes calculating the energy loss of the battery within the time window, calculating the charge loss rate of the battery within the time window based at least in part on the energy loss of the battery within the time window, and determining whether there is an internal short circuit within the battery based on the charge loss rate of the battery and a predetermined threshold. The method includes generating an indication that an internal short circuit exists. In some embodiments, the method includes initiating a battery automatic shutdown operation associated with the battery, transferring a load to another battery, or both in response to the indication that an internal short circuit exists. In some embodiments, the method includes determining an additional time window based on the current as a function of time, calculating an additional energy loss of the battery within the additional time window, calculating an additional charge loss rate of the battery within the additional time window, and determining whether an internal short circuit exists based on the additional charge loss rate of the battery and a predetermined threshold. In some embodiments, the method includes calculating an amount of energy transferred at a set of terminals during a time window during charging of the battery, calculating an amount of energy transferred at a set of terminals during a time window during discharging of the battery, and calculating internal resistance energy losses at the set of terminals during the time window based on a predetermined resistance of the battery. In some embodiments, the energy losses of the battery within the time window are substantially equal to a difference between the calculated amount of energy transferred during charging of the battery and a combination of the amount of energy transferred and the internal resistance energy losses during discharging of the battery. In some embodiments, the method includes determining a predetermined resistance of the battery by measuring. In some embodiments, the method includes calculating an average battery potential during a time window, wherein a charge loss rate of the battery is substantially equal to the energy loss of the battery within the time window divided by the product of the average battery potential during the time window and the duration of the time window. In some embodiments, the method includes calculating a difference between the charge loss rate of the battery and an average charge loss rate of the battery, and determining whether the difference is greater than a predetermined threshold. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram depicting a battery real-time ISC detection system. Figure 2 is a block diagram depicting predetermined values ​​that may be stored in a memory at a battery real-time ISC detection system. Figure 3is a block diagram depicting calculated values ​​that may be calculated by a battery real-time ISC monitoring system and stored in its memory. Figure 4 is a schematic diagram depicting an equivalent circuit used to illustrate the energy parameters of a lithium-ion battery. Figure 5 is a schematic diagram depicting the law of conservation of energy as applied to lithium-ion batteries. Figure 6 is a schematic diagram depicting the law of conservation of charge as applied to lithium-ion batteries. Figure 7 is a plot depicting the recorded current as a function of time at a set of battery terminals and the time window calculated therefrom. Figure 8 is a flow chart depicting a method for real-time ISC detection of a battery. Although the present disclosure is susceptible to various modifications and alternatives, specific embodiments have been shown by way of example in the accompanying drawings and will be described in detail herein. However, it should be understood that the present disclosure is not intended to be limited to the specific form disclosed. On the contrary, it is intended to cover all modifications, equivalents and alternatives that fall within the scope of the present disclosure. DETAILED DESCRIPTION refer to Figure 1 , which depicts a battery real-time ISC detection system 100. The system 100 may include a battery 102, a load or source 128, a processor 108, and a memory 114. Although the description herein is sufficient to illustrate the elements of battery real-time ISC detection, it should be noted that the system 100 may include additional features or elements depending on the specific application of the present disclosure. The battery 102 may include a first terminal 104 and a second terminal 106 as a group. Although only two terminals are depicted in this group of terminals 104, 106, it should be understood that the battery may include additional terminals depending on the internal configuration and application of the battery. A voltage sensor 130 (e.g., a voltmeter) may be connected between the group of terminals 104, 106 to read the voltage therebetween. A current sensor 132 (e.g., an ammeter) may be connected between one of the terminals (e.g., terminal 104) and a load or source 128 to read the current therebetween. The battery 102 may be coupled to a load or source 128 so that the load or source 28 may draw power from the battery 102 or provide power to the battery 102 through the group of terminals 104, 106. The load or source 128 may include one or more electrical systems that draw power from the battery 102 and one or more electrical sources that provide power to the battery 102. In some cases, the load or source 128 may include a low-power system, such as a power system of a portable electronic device. In other cases, the load or source 128 may include a high-power system, such as those used in vehicle (e.g., aircraft) navigation and propulsion, into which the system 100 may be incorporated. Other applications may exist. Processor 108 may include a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a peripheral interface controller (PIC), another type of microprocessor or microcontroller, and / or a combination thereof. In addition, processor 108 may be implemented using an integrated circuit, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a combination of logic gate circuit systems, other types of digital or analog electrical design components, or a combination thereof. Processor 108 may include a set of processing elements, such as processing element 110 and processing element 112. These processing elements 110, 112 may be packaged together or remotely located in a distributed processor configuration. Voltage sensor 130 and current sensor 132 may be coupled to processor 108 to enable processor 108 to receive data therefrom. Although not shown, additional circuitry and components (e.g., analog-to-digital converters, etc.) may be used to help communicate real-time voltage and current from a set of terminals 104, 106 to processor 108. The memory 114 may include a memory device such as a random access memory (RAM), a read-only memory (ROM), a magnetic disk memory, an optical disk memory, a flash memory, another type of memory capable of storing data and processor instructions, etc., or a combination thereof. The memory 114 may store instructions 116 for real-time ISC detection of a battery as described herein. For example, the instructions 116 may be readable by the processor 108 to perform any of the operations described herein. The memory 114 may further store logged data associated with the battery 102, such as voltage 118 as a function of time and current 120 as a function of time. The voltage 118 and current 120 may be periodically sampled by the processor 108 using a voltage sensor 130 and a current sensor 132 to create their respective functions. Predetermined values ​​122 and calculated values ​​124 may also be stored in the memory 114. These values ​​may be used for real-time ISC detection of the battery as described herein. During operation, the voltage sensor 130 may continuously measure the voltage across the set of terminals 104, 106, which may be recorded or logged as a voltage as a function of time 118. Likewise, the current sensor 132 may continuously measure the current across the set of terminals 104, 106, which may be recorded or logged as a current as a function of time 120. As further described herein, based on the voltage 118, the current 120, and the predetermined value 122, a calculated value 124 may be generated, and if ISC is detected, an indication 126 of the presence of ISC may be generated. The predetermined value 122 may be received based on user input, a configuration file, an encoding definition, etc. Figure 2 The predetermined values ​​122 may include a stored comparison value 202, a number 204 of recent charge loss rates, a resistance 206 of the battery 102, and a threshold value 208. Each of the predetermined values ​​122 may be used at some point during the process of ISC detection. Calculations 124 may include various intermediate calculations and data used to determine whether ISC has occurred. Figure 3 , calculated values ​​124 may include cumulative charge value 302, time window 304, amount of energy transferred during charging 306, amount of energy transferred during discharging 308, internal resistance energy loss 312, energy loss 314, average battery potential 316, charge loss rate 318, average charge loss rate 320, and difference 322 between average charge loss rate 320 and charge loss rate 318. Calculation and use of these values ​​for detecting ISC are further described herein. In addition, because the process for ISC detection is continuous and in real time, the processor 108 can continuously calculate and store additional accumulated charge values ​​324, additional time windows 326, additional amounts of energy transferred during charging 328, additional amounts of energy transferred during discharging 330, additional internal resistance energy losses 334, additional energy losses 336, additional average battery potential 338, additional charge loss rates 340, additional or updated average charge loss rates 342, and additional differences 344 between the additional average charge loss rates 342 and the additional charge loss rates 340. The operations described herein with respect to system 100 may rely on the laws of conservation of energy and conservation of charge as they relate to rechargeable batteries. Figure 4 , Figure 5 and Figure 6 can be used to describe these principles.

[0034] refer to Figure 4, which depicts an equivalent circuit 400 for illustrating energy parameters of a lithium-ion battery (e.g., battery 102). Circuit 400 may include a set of terminals 104, 106. Circuit 400 may present a voltage 402 across the set of terminals 104, 106. Likewise, when connected to an external circuit (e.g., a load or source 128), circuit 400 may present a current 404. The energy charged into circuit 400 may be determined based on voltage 402 and current 404, which is mathematically represented herein as E0. Similarly, the charge input into circuit 400 may also be calculated based on current 404 and time, which may be mathematically represented herein as C0. Circuit 400 may include voltage source 418 to represent the stored reusable voltage within a lithium-ion battery, such as battery 102. Voltage source 418 may enable calculation of reusable energy and reusable charge, which may be mathematically represented herein as E1 and C1, respectively. The circuit 400 may further include an internal loss model 406 to represent the losses occurring inside the lithium-ion battery (e.g., battery 102). These losses may be due to resistive leakage and irreversible process losses. Resistive leakage (which may include self-discharge losses) may be represented by a variable resistor 414. Irreversible process losses (which may include lithium losses, electrolyte degradation, activation overpotential losses, concentration overpotential losses, etc.) may be represented by a diode 408, a variable resistor 410, and a capacitor 412. These loss elements may result in a loss current 416 within the circuit 400. The internal loss model 406 may enable the calculation of non-reusable energy losses and non-reusable charge losses, both of which may be mathematically represented herein as E2 and C2, respectively. Circuit 400 may also include resistor 405 to represent the internal resistance of the battery cell due to conductive losses in internal wiring, electrodes, electrolyte, etc. The resistance of resistor 405 may be mathematically represented herein as R, and may enable calculation of internal resistance losses during charge and discharge, which may be mathematically represented herein as E3 and E4, respectively. refer to Figure 5 , the diagram 500 depicts the Figure 4 The energy conservation law associated with the circuit 400. The energy 502 (E0) charged to the battery is equal to the sum of the battery's reusable energy 510 (E1), non-reusable energy loss 508 (E2), internal resistance loss during discharge 506 (E3), and internal resistance loss during charge 504 (E4). refer to Figure 6 , diagram 600 depicts the Figure 4The charge conservation law associated with the circuit 400. The charge 602 (C0) charged to the battery is equal to the sum of the reusable charge 608 (C1) (which is the charge that can be discharged) and the charge loss 604 (C2) due to irreversible processes. refer to Figure 7 , plot 700 depicts a function 706 representing a current 702 as a function of time 704. Function 706 may be used to determine a time window 708 that enables real-time ISC detection of the battery. The time window 708 may correspond to Figure 3 , and can be surrounded by a start time 712 and an end time 710 (in order from most recent to earliest). In addition, the time window 708 can be selected so that it meets at least two criteria. First, during the time window, the cumulative charge can be substantially equal to zero. Second, during the time window, the accumulated absolute value of the charge can be substantially equal to a stored comparison value (e.g., stored comparison value 202). As used herein, the term "substantially equal to" means that the difference falls within a typical engineering tolerance range when real defects in engineering systems are taken into account. The stored comparison value 202 can affect the length of the time window 708. Higher values ​​can result in longer intervals. In some embodiments, the stored comparison value 202 can be a rated battery cell capacity value associated with the battery 102. However, other values ​​can be used based on the desired typical time window duration. Mathematically expressed, the time window 708 may be selected such that: And make Where T start is the start time 712, T stop is the end time 710, i is the function 706, and C W is the stored comparison value 202. The right sides of Equation 1 and Equation 2 may correspond to Figure 3 , where the right side of Equation 1 may be the accumulated charge and the right side of Equation 2 may be the accumulated absolute value of the charge. In order to determine whether there is battery ISC, energy loss can be calculated. Energy loss can be calculated based on the law of conservation of energy. For batteries, the law of conservation of energy can be expressed as: E0=E1+E2+E3+E4, E0 is charged to Figure 4 , or in other words, E0 may be the energy of the circuit 400 depicted in FIG. 1 , or in other words, ... Figure 1), E1 is the amount of energy measured at the set of terminals 104, 106 during discharge, E2 is the energy loss, E3 is the internal resistance loss during discharge, and E4 is the internal resistance loss during charge. Each term in the above equation can be replaced by their calculation as follows (note that E3+E4 is combined into a single integral in the equation below): Where T start yes Figure 7 The start time 712 of the time window 708, T stop is the end time 710 of the time window 708, and v is a function of voltage over time (e.g., Figure 1 The voltage 118), i is the function of the current changing with time (e.g. Figure 1 The current is 120), E2 is the energy loss, and R is Figure 1 The internal resistance of the battery 102. R may correspond to Figure 2 The integrals in the above equations can correspond to Figure 3 The amount of energy transferred during charging 306, the amount of energy transferred during discharging 308, and the internal resistance energy loss 312. E2 may correspond to Figure 3 The energy loss is 314. The internal resistance R can be determined according to the manufacturer's specifications or laboratory testing. The above equation can be rewritten to solve for the energy loss. Once the energy loss E2 is determined, the charge loss rate can be calculated. The charge loss rate can be expressed mathematically as: Where CLR is the charge loss rate, E2 is the energy loss, U avg is Figure 7 The average cell potential over the time window 708, T start is the start time 712 of the time window 708, and T stop is the end time 710 of the time window 708 . Average battery potential U avg It can be expressed mathematically as: Among them U avg is the average cell potential, T start is the start time 712 of the time window 708, T stopis the end time 710 of the time window 708, and v is a function of voltage over time (e.g., Figure 1 The voltage 118), i is the function of the current changing with time (e.g. Figure 1 The current is 120), and R is Figure 1 The internal resistance of the battery 102. Combining Equation 4 and Equation 5 above, the charge loss rate can be expressed as: An ISC condition may exist when the charge loss rate is elevated relative to normal battery operation. To determine whether the charge loss rate is elevated, it may be compared to an average charge loss rate associated with the battery. When the difference between the two is greater than a threshold, it may be determined that ISC is occurring. The average charge loss rate can be expressed mathematically as: The CLR avg is the average charge loss rate, M is the predetermined number of most recently calculated charge loss rates, and each CLR j are different calculated charge loss rates CLR. Although Equation 7 represents the arithmetic mean of the previously calculated charge loss rates, other averages (eg, weighted, median, etc.) are possible. An ISC condition may exist when the difference between the charge loss rate from Equation 6 and the average charge loss rate from Equation 7 is greater than a threshold. This can be expressed mathematically as: |CLR-CLR avg |>δ, (Equation 8) Where CLR is the charge loss rate, CLR avg is the average charge loss rate; and δ is the threshold value. refer to Figure 8 The process of real-time ISC detection can be described in method 800, which can be Figure 1 The method 800 may include inputting a comparison value C at 802. W , resistance R, the number of recent charge loss rates M and a threshold δ. For example, C W may correspond to comparison value 202, R may correspond to resistance 206 of battery 102, M may correspond to number 204 of recent charge loss rates, and δ may correspond to threshold 208. These values ​​may be predetermined by input by a user of system 100, by storage in memory 114, or both. The method 800 may also include measuring the voltage as a function of time and the current as a function of time and logging the data to a storage device at 804. For example, the processor 108 may continuously record the voltage 118 as a function of time and the current 120 as a function of time at a set of terminals 104, 106, which may be stored in the memory 114. The method 800 may also include searching for and determining a dynamic time window at 806. For example, the processor 108 may determine the time window 304 (and / or the time window 708) based on the current 120 as a function of time. During the time window 304, the accumulated charge (which may be one of the accumulated charge values ​​302) may be substantially zero, and the accumulated absolute value of the charge (which may be another one of the accumulated charge values ​​302) may be substantially equal to the stored comparison value (C W ) 202. In some cases, the stored comparison value (C W ) 202 may be a rated cell capacity value associated with the battery. However, other values ​​may also be used. These criteria may be expressed herein as Equations 1 and 2. The method 800 may include calculating energy losses in the time window at 808. For example, the processor 108 may be configured to calculate an amount of energy transferred during charging 306 at the set of terminals 104, 106 during the time window 304 during charging of the battery 102. The processor 108 may be further configured to calculate an amount of energy transferred during discharging 308 at the set of terminals 104, 106 during the time window 304 during discharging of the battery 102. The processor 108 may also be configured to calculate internal resistance energy losses 312 at the set of terminals 104, 106 during the time window 304 based on a predetermined resistance (R) 206 of the battery 102. The energy losses 314 of the battery 102 within the time window 304 may be substantially equal to a difference between the calculated amount of energy transferred during charging 306 of the battery 102 and a combination of the amount of energy transferred during discharging 308 of the battery 102 and the internal resistance energy losses 312. The predetermined resistance (R) 206 of the battery 102 may be determined according to manufacturer specifications or laboratory testing. These calculations may be expressed herein as Equation 3. The method 800 may also include calculating an internal charge loss rate at 810. For example, the processor 108 may calculate the average battery potential 316. The charge loss rate 318 of the battery 102 may be substantially equal to the energy loss 314 of the battery 102 divided by the product of the average battery potential 316 and the duration of the time window, which may be determined by finding the difference between the start time 712 and the end time 710 of the time window 708. These calculations may be represented herein as Equation 6. The method 800 may also include calculating an average internal charge loss rate at 812. For example, the average charge loss rate 320 may be calculated as the arithmetic mean of the predetermined number (M) 204 of the most recently calculated charge loss rates. These calculations may be represented herein by Equation 7. The processor 108 may continuously update the average charge loss rate 320 as additional charge loss rates 340 are calculated. Or in other words, the processor 108 may calculate additional average charge loss rates 342. The method 800 may include comparing the difference between the internal charge loss rate and the average internal charge loss rate to a threshold at 814. For example, the processor 108 may be configured to calculate the difference between the charge loss rate 318 of the battery 102 and the average charge loss rate 320 of the battery 102. The processor 108 may then determine whether the difference is greater than a predetermined threshold δ 208. These calculations may be represented herein as Equation 8. The method 800 may further include: when the difference is not greater than the threshold, repeating the method 800 at 804-814. For example, the processor 108 may continuously repeat determining the additional time window 326 based on the current 120. The processor 108 may further continuously repeat calculating the additional energy loss 336 of the battery 102 within the additional time window 326. The processor may also continuously repeat calculating the additional charge loss rate 340 of the battery 102 within the additional time window 326. Finally, the processor 108 may continuously repeat determining whether ISC is present by comparing the additional charge loss rate 340 of the battery to the average charge loss rate 320 of the battery (or the additional or updated charge loss rate 342). The method 800 may include determining that battery ISC is detected in response to the difference being greater than a threshold at 816. For example, an indication 126 may be generated to provide an alert that an ISC condition exists. Additionally, in response to determining that battery ISC is detected, mitigation steps may be taken at the battery 102, which may include initiating a battery auto-shutdown operation associated with the battery 102. It should be noted that the embodiments herein are described in terms of continuous functions and integrals of these functions (e.g., ∫f(x)). However, since the described embodiments can measure data in discrete time periods, the present disclosure and claims should be interpreted as being equally applicable to discrete functions and sums of these functions (e.g., ∑f[n]). In other words, as used herein, continuous functions and continuous function operations should be understood to be interchangeable with their corresponding discrete functions and discrete function operations (i.e., ∫f(x) can be used interchangeably with ∑f[n]). While various embodiments have been shown and described, the disclosure is not limited thereto, and is to be construed to include all such modifications and variations as would be apparent to those skilled in the art.

Claims

1. A system (100), comprising: a battery (102) having a set of terminals (104, 106); One or more processing elements (110, 112) configured to: continuously recording a voltage as a function of time (118) and a current as a function of time (120) at the set of terminals (104, 106); determining a time window (304) based on the current (120) as a function of time, wherein during the time window (304) the accumulated charge (302) is substantially zero, and wherein during the time window (304) the accumulated absolute value of the charge (302) is substantially equal to the stored comparison value (202); calculating energy loss (314) of the battery (102) within the time window (304); calculating a charge loss rate (318) of the battery (102) within the time window (304) based at least in part on the energy loss (314) of the battery (102) within the time window (304); determining whether an internal short circuit exists within the battery (102) based on the charge loss rate (318) and a predetermined threshold (208); and In response to determining that the internal short circuit exists, an indication that the internal short circuit exists is generated (126).

2. The system (100) of claim 1, wherein the one or more processing elements (110, 112) are further configured to, in response to the indication (102) that the internal short circuit exists, initiate a battery (102) automatic shutdown operation associated with the battery (102), transfer a load (128) to another battery, or both.

3. The system (100) of claim 1, wherein the one or more processing elements (110, 112) are further configured to: continuously repeating determining additional time windows (326) based on the current (120) as a function of time; Continuously and repeatedly calculating an additional energy loss (336) of the battery (102) within the additional time window (326); continuously and repeatedly calculating an additional charge loss rate (340) of the battery (102) within the additional time window (326); and The determination of whether the internal short circuit exists is continuously repeated based on the additional charge loss rate (340) of the battery (102) and the predetermined threshold (208).

4. The system (100) of claim 3, wherein the one or more processing elements (110, 112) are further configured to continuously update an average charge loss rate (320) of the battery (102) based on a predetermined number of most recently calculated additional charge loss rates (204).

5. The system of claim 1, wherein the stored comparison value (202) is a rated cell capacity value associated with the battery (102).

6. The system (100) of claim 1, wherein as part of calculating the energy loss (314) of the battery within the time window (304), the one or more processing elements (110, 112) are configured to: calculating a magnitude (306) of energy transferred at the set of terminals (104, 106) during the time window (304) during charging of the battery (102); calculating a magnitude (308) of energy transferred at the set of terminals (104, 106) during the time window (304) during discharge of the battery (102); and calculating an internal resistance energy loss (312) at the set of terminals (104, 106) during the time window (304) based on a predetermined resistance (206) of the battery (102), wherein the energy loss (314) of the battery (102) within the time window (304) is substantially equal to a calculated difference between the amount (308) of energy transferred during charging of the battery (102) and a combination of the amount (308) of energy transferred during discharging of the battery (102) and the internal resistance energy loss (312).

7. The system (100) of claim 6, wherein the predetermined resistance of the battery (206) is determined by manufacturer specifications or laboratory testing.

8. The system (100) of claim 1, wherein as part of calculating the charge loss rate (318) of the battery (102) within the time window (304), the one or more processing elements (110, 112) are configured to calculate an average battery potential (316) during the time window (304), wherein the charge loss rate (316) of the battery (102) is substantially equal to the energy loss (314) of the battery (102) within the time window (304) divided by the product of the average battery potential (316) during the time window (304) and the duration of the time window (304).

9. The system (100) of claim 1, wherein as part of determining whether an internal short circuit exists, the one or more processing elements (110, 112) are configured to: calculating an average charge loss rate (320) of the battery (102) based on a predetermined number of most recently calculated charge loss rates (204); calculating a difference (322) between the charge loss rate (318) of the battery (102) and the average charge loss rate (320) of the battery (102); and A determination is made as to whether the difference (322) is greater than the predetermined threshold (208).

10. The system (100) of claim 1, wherein the battery (102) and the one or more processing elements (110, 112) are incorporated into an aircraft.

11. A system (100) comprising a processor (108) and a memory (114), wherein the memory (114) stores instructions that, when executed by the processor (108), cause the processor (108) to: continuously recording a voltage as a function of time (118) and a current as a function of time (120) at a set of terminals (104, 106) of a battery (102); By selecting the start time (710) of the time window that substantially satisfies the following equation: start and the end time (712) T of the time window stop , determining the time window (304) based on the current (120) as a function of time: and where i is the current (120) as a function of time, and where C W is the stored comparison value (202); calculating energy loss (314) of the battery (102) within the time window (304); calculating a charge loss rate (318) of the battery (102) within the time window (304) based at least in part on the energy loss (318) of the battery (102) within the time window (304); determining whether an internal short circuit exists within the battery (1102) based on the charge loss rate (318) of the battery (102) and a predetermined threshold (208); and In response to determining that the internal short circuit exists, an indication that an internal short circuit exists is generated (126).

12. The system (100) of claim 11, wherein the energy loss (314) of the battery (102) within the time window (304) substantially satisfies the following equation: Where E2 is the calculated energy loss (314) of the battery (102), v is the voltage (118) as a function of time, and R is the predetermined resistance (206) of the battery (102).

13. The system (100) of claim 11, wherein the charge loss rate (318) of the battery (102) within the time window (304) substantially satisfies the following equation: wherein CLR is the charge loss rate (318) of the battery (102) within the time window (304), E2 is the calculated energy loss (314) of the battery (102), v is the voltage (118) as a function of time, and R is a predetermined resistance (206) of the battery (102).

14. A method comprising: continuously recording (804) a voltage (118) as a function of time and a current (120) as a function of time at a set of terminals (104, 106) of a battery (102); determining a time window (304) based on the current (120) as a function of time, wherein during the time window (304) the accumulated charge (302) is substantially zero, and wherein during the time window (304) the accumulated absolute value of the charge (302) is substantially equal to the stored comparison value (202); calculating (808) an energy loss (314) of the battery (102) within the time window (304); calculating (810) a charge loss rate (318) of the battery (102) within the time window (304) based at least in part on the energy loss (318) of the battery (102) within the time window (304); determining (814) whether an internal short circuit exists within the battery (102) based on the charge loss rate (318) of the battery (102) and a predetermined threshold (208); and An indication (126) that the internal short circuit exists is generated (816).

15. The method of claim 14, further comprising initiating a battery (102) automatic shutdown operation associated with the battery (102), transferring a load (128) to another battery, or both, in response to the indication (126) that the internal short circuit exists.

16. The method according to claim 14, further comprising: determining an additional time window (326) based on the current (120) as a function of time; calculating an additional energy loss (336) of the battery (102) within the additional time window (326); calculating an additional charge loss rate (340) of the battery (102) within the additional time window (326); and A determination is made as to whether the internal short circuit exists based on the additional charge loss rate (340) of the battery (102) and the predetermined threshold (208).

17. The method according to claim 14, further comprising: calculating a magnitude (306) of energy transferred at the set of terminals (104, 106) during the time window (304) during charging of the battery (102); calculating a magnitude (308) of energy transferred at the set of terminals (104, 106) during the time window (304) during discharge of the battery (102); and calculating an internal resistance energy loss (312) at the set of terminals (104, 106) during the time window (304) based on a predetermined resistance of the battery (206), wherein the energy loss (314) of the battery (102) within the time window (304) is substantially equal to a difference between the calculated amount (306) of energy transferred during charging of the battery (102) and a combination of the amount (308) of energy transferred during discharging of the battery (102) and the internal resistance energy loss (312).

18. The method of claim 17, further comprising determining the predetermined resistance (206) of the battery (102) by measurement.

19. The method according to claim 14 further includes calculating an average battery potential (316) during the time window (304), wherein the charge loss rate (318) of the battery (102) is substantially equal to the energy loss (314) of the battery (102) within the time window (304) divided by the product of the average battery potential (316) during the time window (304) and the duration of the time window (304).

20. The method of claim 14, further comprising: calculating a difference (322) between the charge loss rate (318) of the battery (102) and an average charge loss rate (320) of the battery (102); and A determination is made as to whether the difference (322) is greater than a predetermined threshold (208).

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