Method and apparatus for estimating state of charge of battery

Abstract

The invention provides a method for estimating the state of charge of a battery, and the method comprises the following steps: S1, obtaining the reference power consumption of a slave control unit of a battery management system connected with the battery, and determining the reference power consumption in an offline manner; s2, acquiring actual working condition information of the slave control unit in an actual operation scene; s3, determining the actual power consumption of the slave control unit based on the reference power consumption of the slave control unit and the actual working condition information; and S4, estimating the state of charge of the battery based on the actual power consumption of the slave control unit. The application also proposes an apparatus for estimating the state of charge of a battery, a battery management system, a battery system, a vehicle and a computer program product.

Description

Technical Field

[0001] The present application relates to a method for estimating the state of charge of a battery. The present application also relates to a device for estimating the state of charge of a battery, a battery management system, a battery system, a vehicle and a computer program product. Background Art

[0002] The battery management system (BMS) is a key component to ensure the safe and efficient operation of batteries in electric vehicles and energy storage systems. One of the core functions of the battery management system is to accurately estimate the battery's state of charge (SOC), which is crucial for battery energy management, life prediction, and performance optimization.

[0003] Traditional battery state of charge estimation methods include the ampere-hour integration method. Although this method is widely used, it has limitations in the accuracy of collecting fine currents, which means that when estimating the battery state of charge online, the power consumption of the slave control unit of the battery management system cannot be fully considered. This unaccounted-for power consumption may accumulate over time and cause the accuracy of the battery state of charge estimation to decrease.

[0004] Therefore, the prior art still has deficiencies in estimating the state of charge of the battery. Summary of the invention

[0005] The purpose of the present application is to provide a method for estimating the state of charge of a battery, a device for estimating the state of charge of a battery, a battery management system, a battery system, a vehicle and a computer program product to at least solve some of the problems in the prior art.

[0006] According to a first aspect of the present application, a method for estimating a state of charge of a battery is provided, the method comprising the following steps:

[0007] S1: Acquire a reference power consumption of a slave control unit of a battery management system connected to a battery, wherein the reference power consumption is determined in an offline manner;

[0008] S2: Acquiring actual operating condition information of the slave control unit in an actual operation scenario;

[0009] S3: determining the actual power consumption of the slave control unit based on the reference power consumption of the slave control unit and the actual operating condition information; and

[0010] S4: Estimate the state of charge of the battery based on the actual power consumption of the slave control unit.

[0011] This application particularly includes the following technical ideas: by combining the offline test technology of the slave control unit with the actual working condition information, it not only cleverly avoids the high-precision requirements of the current acquisition equipment in actual use, but also dynamically considers various complex situations encountered in actual use. It improves the flexibility and accuracy of the battery management system in estimating the battery state of charge.

[0012] In an exemplary embodiment, step S4 includes: using the main control unit of the battery management system to estimate the rough state of charge of the battery by time integrating the charge and discharge current of the battery over a predetermined time period; and correcting the rough state of charge based on the actual power consumption of the slave control unit to obtain the precise state of charge of the battery, and determining the precise state of charge as the state of charge of the battery. In this way, the traditional state of charge estimation strategy can be optimized without significantly changing the existing battery management system architecture.

[0013] In an exemplary embodiment, the actual working condition information includes the actual working time of the slave control unit under each preset working condition within a predetermined time period, and step S3 includes: calculating the actual power consumption of the slave control unit by the following formula using a time weighted method:

[0014]

[0015] Among them, P act is the actual power consumption of the slave control unit, P ref,i is the reference power consumption of the slave control unit under the i-th preset working condition, t i is the actual working time of the slave control unit under the i-th preset working condition, m is the number of preset working conditions involved in the slave control unit within the predetermined time period, and N is the number of slave control units included in the battery management system. Therefore, the actual power consumption of the slave control unit can be more accurately estimated according to the working time distribution of the slave control unit under different working conditions, thereby improving the accuracy of the charge state estimation.

[0016] In an exemplary embodiment, step S2 includes: using the battery management system to monitor the current direction, current magnitude, type and voltage of the connected charging interface of the battery to identify the preset working condition of the slave control unit, and using the timing chip of the battery management system to record the actual working time of the slave control unit under the preset working condition. This power consumption calculation method that distinguishes working conditions takes into account the energy consumption changes of the slave control unit under different working conditions, and improves the accuracy of charge state estimation.

[0017] In an exemplary embodiment, the actual working condition information includes the actual working conditions of the slave control unit under various preset working conditions within a predetermined time period, and step S3 includes: correcting the reference power consumption according to the deviation between the actual working condition and the reference working condition used when determining the reference power consumption in an offline manner, and determining the actual power consumption based on the corrected reference power consumption. Thus, the reference power consumption can be corrected more accurately, thereby improving the estimation accuracy of the actual power consumption.

[0018] In an exemplary embodiment, step S3 includes: determining a correction factor according to a deviation between the actual working condition and the reference working condition, and correcting the reference power consumption by superimposing the correction factor on the reference power consumption, wherein the correction factor is determined based on the deviation between the actual working condition and the reference working condition in terms of temperature, humidity, vehicle load and / or road conditions. The correction factor can be used to quantify the difference between the offline test condition and the actual working condition, and the power consumption calibration value can be dynamically adjusted.

[0019] In an exemplary embodiment, the preset operating conditions include normal operating conditions and energy-saving operating conditions, in which the slave control unit is continuously connected, and in which the slave control unit is turned off or only periodically connected; and / or, the preset operating conditions include: DC charging conditions, AC charging conditions, driving discharge conditions, timed wake-up conditions, sleep balance conditions, and full sleep conditions. Considering that the actual power consumption of the slave control unit will change with the operating conditions, by defining multiple preset operating conditions, an adaptive reference power consumption can be dynamically selected. Compared with using a single static power consumption reference, it can ensure the accuracy of power consumption estimation even when the operating conditions change.

[0020] In an exemplary embodiment, the reference power consumption and / or actual power consumption of the slave control unit under the energy-saving operating condition is determined in the following manner: for the case where the slave control unit is in an operating state and a non-operating state in the energy-saving operating condition, the reference power consumption and / or actual power consumption of the slave control unit is determined separately. By distinguishing the energy-saving power consumption of different operating states, a more refined energy-saving power consumption estimation can be achieved.

[0021] In an exemplary embodiment, step S1 includes: performing offline power consumption test on the actually used and / or other slave control units under a series of preset working conditions; and, for each slave control unit tested offline, obtaining its average power consumption per unit time under each preset working condition, and determining the reference power consumption based on the average power consumption per unit time. Through offline power consumption test, the dependence on high-precision current and voltage sampling equipment can be reduced in actual application scenarios, the calculation burden and hardware cost can be reduced, and the charge state estimation accuracy of the battery management system can be ensured.

[0022] In an exemplary embodiment, step S1 includes: simulating the battery state and / or load change under each preset working condition by means of a simulation test tool, and for each preset working condition, measuring the current and voltage of the actually used and / or other slave control units by means of a high-precision current and voltage measurement unit within the test time; and, for each slave control unit tested offline, calculating its average power consumption per unit time by the following formula:

[0023]

[0024] Among them, P i is the average power consumption per unit time of the slave control unit under the i-th preset working condition, t i1 is the test start time of the i-th preset working condition, t i2 is the test end time of the i-th preset working condition, V i (t) is the voltage of the slave control unit under the i-th preset working condition, I i (t) is the current of the slave control unit under the i-th preset operating condition.

[0025] In an exemplary embodiment, step S1 includes: storing the reference power consumption determined by the slave control unit in an offline manner in a calibration database locally and / or in the cloud of the battery management system; and, in response to the battery state of charge estimation requirement and / or charge state correction requirement, retrieving the reference power consumption from the calibration database locally and / or in the cloud of the battery management system. By storing the offline measurement results, it is possible to ensure that these reference data can be quickly and accurately called in the actual operation of the battery management system, thereby improving the accuracy and efficiency of battery state of charge estimation and reducing the real-time calculation burden.

[0026] According to a second aspect of the present application, a device for estimating the state of charge of a battery is provided, the device comprising a memory and a processor, the memory storing computer program instructions, and when the computer program instructions are executed by the processor, the processor is capable of executing the method described in the first aspect of the present application.

[0027] According to a third aspect of the present application, a battery management system is provided, the battery management system comprising a master control unit and a slave control unit, the master control unit comprising the device according to the second aspect of the present application.

[0028] In an exemplary embodiment, the battery management system includes a human-machine interface, which is configured to: output the state of charge of the battery and / or output a rough state of charge that is not corrected based on the actual power consumption of the slave control unit; adjust the estimation frequency of the state of charge of the battery according to the user's input data; and / or, adjust the type and number of preset operating conditions considered when calculating the actual power consumption of the slave control unit according to the user's input data. This provides the user with instant information on the battery state of charge and an overview of the battery power at different correction levels.

[0029] According to a fourth aspect of the present application, a battery system is provided, comprising a battery and a battery management system according to the third aspect of the present application connected to the battery.

[0030] According to the fifth aspect of the present application, a vehicle is provided, which includes the device according to the second aspect of the present application, the battery management system according to the third aspect of the present application and / or the battery system according to the fourth aspect of the present application.

[0031] According to a sixth aspect of the present application, a computer program product having a program code unit is provided, wherein the program code unit is configured to cause the computer to execute the method according to the first aspect of the present application when the computer program product is run on a computer or stored on a computer-readable storage medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present application will be described in more detail below with reference to the accompanying drawings, so that the principles, features and advantages of the present application can be better understood. The accompanying drawings include:

[0033] Figure 1 A block diagram of a battery system according to an exemplary embodiment of the present application is shown;

[0034] Figure 2 A block diagram showing a detailed configuration of a main control unit of a battery management system according to an exemplary embodiment of the present application;

[0035] Figure 3 A block diagram of an offline test circuit for determining a reference power consumption of a slave control unit of a battery management system according to an exemplary embodiment of the present application is shown;

[0036] Figure 4 A flow chart of a method for estimating the state of charge of a battery according to an exemplary embodiment of the present application is shown;

[0037] Figure 5 Shows Figure 4 A flow chart of step S1 of the method shown;

[0038] Figure 6Shows Figure 4 A flowchart of steps S2 and S3 of the method shown; and

[0039] Figure 7 Shows Figure 4 Flowchart of steps S2 and S3 of the method shown. DETAILED DESCRIPTION

[0040] In order to make the technical problems, technical solutions and beneficial technical effects to be solved by the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and multiple exemplary embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the scope of protection of the present application.

[0041] Figure 1 A block diagram of a battery system 1 is shown. The battery system 1 may be installed in a vehicle, for example. The vehicle may be provided with driving power for traveling by the battery 10, or may be provided with operating power for operating electronic components such as audio, air conditioning, etc. by the battery 10. In the context, the vehicle may be, for example, a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), an extended range electric vehicle (EREV), or a pure electric vehicle (BEV).

[0042] The battery system 1 includes a battery 10 (also commonly referred to as a battery pack) and a battery management system 20. The battery 10 includes a plurality of battery modules M1, M2, M3 connected in series and / or in parallel, and the battery modules M1, M2, M3 further include a plurality of battery cells C1, C2, C3 coupled in series. In practical applications, the output power of the battery 10 can be adjusted by increasing or decreasing the number of connected battery modules M1, M2, M3. Figure 1 In the embodiment, the external device 50 is connected between the two output terminals OUT+ and OUT- of the battery 10, so that the battery 10 can provide the required power to the external device 50. The external device 50 can be a load (such as a drive motor, an ECU, etc.) or a secondary battery.

[0043] like Figure 1 As shown, the battery management system 20 is a master-slave architecture, which includes, for example, a master control unit BCU and a plurality of slave control units BMU1 , BMU2 , and BMU3 .

[0044] The main control unit BCU is used to monitor or adjust the overall state and function of the battery 10. The state includes, for example, voltage, current and / or temperature. The main control unit BCU is communicatively connected to multiple slave control units BMU1, BMU2, BMU3 to collect information from each slave control unit BMU1, BMU2, BMU3 and control their operation. The communication between the main control unit BCU and the slave control units BMU1, BMU2, BMU3 can adopt a variety of protocols, such as CAN bus or wireless communication, to ensure the real-time and reliability of data transmission. The main control unit BCU is also responsible for estimating the state of charge of the battery 10. Typically, the main control unit BCU receives the current measurement result from the current measurement unit 22 arranged in the main charge and discharge loop, and estimates the rough state of charge of the battery 10 based on the result with the help of the ampere-hour integration method. Figure 1 In the embodiment, the current measuring unit 22 is exemplarily connected between the positive electrode of the battery 10 and the output terminal OUT+. It should be noted that the main control unit BCU and the current measuring unit 22 are Figure 1 Although shown as a separate component, the current measuring unit 22 can also be part of the main control unit BCU.

[0045] Each slave control unit BMU1, BMU2, BMU3 is connected to the corresponding battery module M1, M2, M3, and is responsible for monitoring the real-time status of each battery module M1, M2, M3, which includes, for example, key parameters such as the voltage, current, and temperature of the battery cells C1, C2, C3 in each battery module. The slave control units BMU1, BMU2, and BMU3 transmit these data to the master control unit BCU, so the master control unit BCU processes these data and executes the battery management strategy. The slave control units BMU1, BMU2, and BMU3 are also used to perform voltage balancing operations when there are differences in the voltages of the battery modules M1, M2, and M3. For example, the slave control units BMU1, BMU2, and BMU3 can form a current path at both ends of each battery module M1, M2, and M3 (or battery cells C1, C2, and C3), and set a switch element on the current path. By controlling the switch element, the voltage of each battery module M1, M2, and M3 can be reduced or increased. In this way, voltage balancing can be achieved.

[0046] In terms of power supply, the master control unit BCU is powered by a DC / DC converter or a secondary battery (not specifically shown) disposed between the output terminals OUT+ and OUT- of the battery 10, while the slave control units BMU1, BMU2, and BMU3 are directly powered by the battery modules M1, M2, and M3 they monitor. The power supply mode of the master control unit BCU and the slave control units BMU1, BMU2, and BMU3 has a direct impact on the accuracy of the charge state estimation.

[0047] The above power supply mode of the main control unit BCU determines that it is already located in the main charge and discharge circuit of the battery, so its own influence as a load can be reflected by the measurement value of the current measurement unit 22 located in the main charge and discharge circuit. Therefore, the power consumption of the main control unit BCU has been reflected and considered in the traditional charge state estimation.

[0048] In contrast, the slave control units BMU1, BMU2, and BMU3 are directly powered by the battery modules M1, M2, and M3 they monitor. Their own working current is actually diverted from the current of the battery modules M1, M2, and M3. This part is not directly reflected in the current measurement value of the main circuit, so it is easy to be ignored when estimating the state of charge with the help of ampere-hour integration. Since the electric energy consumed by the slave control units BMU1, BMU2, and BMU3 directly reduces the actual available energy of the battery modules M1, M2, and M3, if it is not taken into account in the state of charge estimation, it will cause the estimated state of charge to be too high, thereby affecting the battery management system 20's accurate judgment of the remaining battery power. In order to accurately evaluate this impact, in theory, it is necessary to use high-precision current detection equipment to monitor the current of the control units BMU1, BMU2, and BMU3. However, in practical applications, such high-precision current measurement equipment is not only costly but also leads to a significant increase in the volume of the battery management system.

[0049] In the above context, the battery management system 20 further includes a device 21 for estimating the state of charge of the battery 10. Figure 1 In the embodiment shown, for example, the device is arranged in the main control unit BCU. The device 21 comprises a processor and a memory, wherein the memory stores computer program instructions. When the computer program instructions are executed by the processor, the processor can, for example, execute a method for estimating the state of charge of a battery (which will be described below with reference to Figure 4 Detailed description). The computer program instructions may be stored in a computer-readable storage medium. The computer-readable storage medium may include, for example, a high-speed random access memory, and may also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card, a secure digital card, a flash memory card, at least one disk storage device, a flash memory device, or other volatile solid-state storage devices. The processor may be a central processing unit, or may be other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0050] like Figure 1As shown, the battery management system 20 may also optionally include a human-machine interface 25, which is configured to output the state of charge of the battery 10 and / or output a rough state of charge that is not corrected based on the actual power consumption of the slave control units BMU1, BMU2, and BMU3. In addition, the human-machine interface 25 can also adjust the estimation frequency of the state of charge of the battery 10 according to the user's input data. The human-machine interface 25 can also adjust the type and number of preset operating conditions considered when calculating the actual power consumption according to the user's input data. This allows the user to adjust the state of charge estimation frequency as needed, and select the type and number of operating conditions that need to be focused on according to actual needs (such as computing overhead and time efficiency). This increases the personalization and adaptability of system operation.

[0051] Figure 2 A block diagram showing a detailed configuration of a main control unit BCU of a battery management system 20 according to an exemplary embodiment of the present application.

[0052] like Figure 2 As shown, the main control unit BCU may include, in addition to the device 21 for estimating the battery state of charge, a SOC estimation unit 27 , a timing chip 28 and a communication unit 29 .

[0053] The SOC estimation unit 27 estimates the rough state of charge of the battery by the ampere-hour integration method based on the measurement value of the current measurement unit 22 in the main charge and discharge circuit.

[0054] The timing chip 28 is used to provide an accurate time reference. In addition, it can also record the actual working time of the slave control units BMU1, BMU2, and BMU3 in each preset working condition.

[0055] The communication unit 29 is responsible for sending instructions to each slave control unit BMU1 , BMU2 , BMU3 and receiving data to control the working mode of the slave control unit battery 1 .

[0056] In this embodiment, the device 21 can, for example, act as a correction unit, which receives the rough state of charge of the battery 10 from the SOC traditional estimation unit 27 and reads the actual working time of the slave control units BMU1, BMU2, and BMU3 under each preset working condition from the timing chip 28, and then uses the calculated actual power consumption of the slave control units BMU1, BMU2, and BMU3 to correct the traditional estimation result of the state of charge to improve the estimation accuracy.

[0057] Figure 3 A block diagram of an offline test circuit for determining a reference power consumption of a slave control unit of a battery management system according to an exemplary embodiment of the present application is shown. The offline test circuit includes a battery system 1' to be tested, a simulation test tool 40, a high-precision current measurement unit 41, a high-precision voltage measurement unit 42, and an offline calculation unit 47.

[0058] In an exemplary embodiment of the present application, the battery management system 20 actually used can be directly disassembled to test the slave control units BMU1, BMU2, and BMU3 separately. In another embodiment, the other slave control units BMU1', BMU2', and BMU3' contained in another battery management system 20' of the same specification can also be tested, and the test results can be applied to the slave control units BMU1, BMU2, and BMU3 actually used. The battery 10' (battery modules M1', M2', M3' and battery cells C1', C2', C3'), connectors, and the main control unit BCU' of the battery management system 20' and the remaining hardware and software configurations used in the offline test should also strictly follow the design standards of the battery system 1 in actual applications.

[0059] The simulation test tool 40 generally includes a host computer and a test bench, which is connected to the output terminals OUT+ and OUT- of the battery system 1' to be tested to simulate the battery state and / or load changes under various preset working conditions. It provides a controllable test environment for the slave control units BMU1', BMU2', and BMU3' to ensure the consistency and repeatability of the test conditions.

[0060] In order to achieve high-precision measurement, each slave control unit BMU1', BMU2', BMU3' is equipped with a separate high-precision current measurement unit 41 and a high-precision voltage measurement unit 42, which can monitor and record the current and voltage of each slave control unit BMU1', BMU2', BMU3' under different preset working conditions in real time and send them to the offline calculation unit 47. Specifically, the high-precision voltage measurement unit 42 is connected to both ends of each slave control unit to measure its voltage. The high-precision current measurement unit 41 measures the current flowing through the slave control unit.

[0061] The offline calculation unit 47 is responsible for collecting and processing data from the high-precision current measurement unit 41 and the high-precision voltage measurement unit 42, and performing offline power consumption calculation and analysis according to the test time, so as to determine the average power consumption per unit time of each slave control unit BMU1', BMU2', BMU3' under each preset working condition. After obtaining the average power consumption per unit time of each slave control unit, the offline calculation unit 47 can further perform data processing (such as calculating the average value, eliminating outliers and / or filtering, etc.) and determine the reference power consumption of the slave control unit under each preset working condition.

[0062] Before offline testing, for example, the ambient temperature can be controlled to be maintained at 25±2°C, the humidity can be controlled to be maintained at 40%-60%, and external battery interference can be shielded. The battery system actually used or with the same specifications is disassembled, and the high-precision current measurement unit 41 and the high-precision voltage measurement unit 42 (for example, current accuracy ≤0.01mA, measurement range 0A-5A; voltage accuracy ≤0.01mV, measurement range 0V-100V) are connected to the slave control unit loop. Then, a series of preset working conditions are simulated with the help of the simulation test tool 40, and the data captured by the high-precision current and voltage measurement units 41 and 42 are recorded at the same time, providing an accurate data basis for the reference power consumption analysis of the slave control units BMU1', BMU2', and BMU3'.

[0063] In an embodiment not shown, multiple (e.g., 5) battery systems of the same specification may be tested offline in parallel. The test time for each preset working condition is, for example, at least 200 hours. By averaging the offline test results of multiple slave control units in terms of quantity and time, the reliability and accuracy of the reference power consumption obtained may be effectively improved.

[0064] Figure 4 A flow chart of a method for estimating the state of charge of a battery according to an exemplary embodiment of the present application is shown.

[0065] In step S1, a reference power consumption of a slave control unit of a battery management system connected to a battery is obtained, where the reference power consumption is determined in an offline manner.

[0066] In one embodiment, the reference power consumption is determined for a plurality of different preset working conditions. For example, the reference power consumption of the slave control unit is composed of a plurality of sub-items, each of which represents the average power consumption of one or more slave control units in a preset working condition and within a unit time.

[0067] In one embodiment, the reference power consumption can be obtained by performing an offline power consumption test on the actually used and / or other slave control units. The offline test results are usually stored in advance so as to be called when needed.

[0068] In one embodiment, the reference power consumption data of the slave control unit can also be collected by crowdsourcing. For example, offline test results of the slave control unit can be collected from laboratories around the world. These laboratories may perform offline power consumption tests under different environmental conditions, and for example, take into account factors such as different road conditions, temperature, humidity, and simulated driving habits, thereby generating diverse reference data. The server collects and stores this data to form a large-scale reference power consumption database. Vehicles in different regions can connect to the server through the network, and call the most matching reference power consumption to estimate the battery state of charge according to their specific environmental conditions and needs.

[0069] In step S2, actual operating condition information of the slave control unit is obtained in an actual operating scenario.

[0070] The actual working condition information includes two aspects of information:

[0071] One is the actual working time of the slave control unit under various preset working conditions within a predetermined time period. Here, the length of the predetermined time period can be adjusted according to actual needs. Generally, the predetermined time period is, for example, the time interval from the last battery state of charge estimation. For example, the preset working condition of the slave control unit can be identified by monitoring the current direction, magnitude, type of charging interface engaged, and voltage of the battery with the help of the battery management system. The direction and magnitude of the current can indicate whether the battery is charging or discharging, while the voltage and temperature measurements can provide more details about the current state of the battery. Then, the actual working time of the slave control unit under the preset working conditions can be recorded using the (RTC) timing chip or other time recording device built into the battery management system.

[0072] The second is the actual working conditions of the slave control unit under various preset working conditions within a predetermined time period. This includes a series of environmental parameters that may affect battery performance (such as temperature, humidity, ambient air pressure, weather conditions, road slope and road condition information). In addition, the actual working conditions may also include state parameters of the vehicle and / or battery management system (such as charge and discharge rates, chemical reaction rates inside the battery, vehicle load, vehicle speed, acceleration or deceleration). These parameters can be detected by the vehicle's own sensors or obtained from the outside with the help of a communication interface. By comprehensively analyzing the parameters of the above-mentioned reaction working conditions, the battery management system can more accurately evaluate the state of the slave control unit in actual use.

[0073] In step S3, the actual power consumption of the slave control unit is determined based on the reference power consumption of the slave control unit and the actual operating condition information.

[0074] The actual power consumption can be determined in a variety of ways. For example, the reference power consumption can be selected in a targeted manner according to the preset working condition type, number, and duration contained in the actual working condition information, and then the actual power consumption is calculated based on the selected reference power consumption. For another example, the reference power consumption can be corrected according to the actual working condition information, and then the actual power consumption is calculated based on the corrected reference power consumption. This will be combined with Figure 6 and Figure 7 The detailed description will not be repeated here.

[0075] In step S4, the state of charge of the battery is estimated based on the actual power consumption of the slave control unit.

[0076] In one embodiment, the battery state of charge estimation process is performed in two stages.

[0077] First, the main control unit of the battery management system receives the battery charge and discharge current from the current measurement unit located in the main charge and discharge circuit, and estimates the rough state of charge of the battery by time integrating the current over a predetermined time period. This preliminary estimation process can be expressed by the following formula:

[0078]

[0079] Among them, SOC is the rough state of charge, SOC 0 is the starting state of charge at the beginning of the estimation, I(t) is the charge and discharge current value of the battery during the estimation period (negative for charging, positive for discharging), Q is the nominal capacity of the battery, t1 represents the start time of the estimation, and t2 represents the end time of the estimation.

[0080] Then, the rough state of charge is corrected using the actual power consumption of the slave control unit to obtain the precise state of charge of the battery. The precise state of charge can be finally determined as the state of charge of the battery. This correction process can be expressed by the following formula:

[0081]

[0082] Among them, SOC′ is the precise state of charge of the battery, SOC is the rough state of charge, and P act is the actual power consumption of the slave control unit during the estimation period (ie, within a predetermined time period), and Q is the nominal capacity of the battery.

[0083] As an alternative, the two stages mentioned above can be combined and the state of charge can be estimated directly using the following formula:

[0084]

[0085] Among them, SOC′ is the precise state of charge of the battery, SOC 0 To estimate the initial state of charge at the beginning, P act is the actual power consumption of the slave control unit during the estimation period, Q is the nominal capacity of the battery, t1 represents the start time of the estimation, t2 represents the end time of the estimation, and I(t) is the charge and discharge current value of the battery during the estimation period (negative for charging, positive for discharging).

[0086] Figure 5 Shows Figure 4 Flow chart of step S1 of the method shown. In this embodiment, Figure 4 Step S1 of the method shown comprises, for example, sub-steps S11 to S14 .

[0087] In sub-step S11, the slave control unit and / or other slave control units actually used in the battery management system are tested for offline power consumption under a series of preset working conditions. Specifically, the battery state and / or load changes under each preset working condition can be simulated by means of a simulation test tool, and for each preset working condition, the current and voltage of the actually used and / or other slave control units are measured within the test time by means of a high-precision current measurement unit and a high-precision voltage measurement unit.

[0088] In one embodiment, the preset operating conditions include normal operating conditions and energy-saving operating conditions. In normal operating conditions, the slave control unit is continuously connected or operates at full power to meet the frequent needs for battery status monitoring when the vehicle is driving or charging. In this case, the slave control unit needs to monitor the voltage, current, temperature and other parameters of the battery module (and the battery cell) in real time to ensure the safety and stability of the battery under high load. In energy-saving operating conditions, the slave control unit is turned off or only periodically connected to meet the reduced battery monitoring needs when the vehicle is parked and turned off, and to achieve energy saving.

[0089] Normal operating conditions include, for example:

[0090] AC charging condition, in which AC charging equipment is used to charge the vehicle or battery system;

[0091] DC charging conditions, in which a DC charging device is used to charge the vehicle or battery system;

[0092] · Driving discharge conditions, which include, for example, the CLTC (China Light-duty Vehicle Test Cycle) condition. The CLTC condition is a driving condition standard unique to China, which comprehensively considers multiple factors such as China's road conditions, traffic conditions, driving habits, etc. and is mainly used to test the energy consumption and emissions of light vehicles. The total duration of the CLTC condition is 1800 seconds and includes, for example, three speed ranges: low speed, medium speed, and high speed, to simulate the energy consumption and emissions of urban congested sections, normal urban driving and suburban sections, and highway sections. The driving discharge condition can be adaptively adjusted according to regional characteristics. For example, the test time allocation, average vehicle speed, and idle speed ratio of the vehicle speed range can be changed to match the traffic conditions and driving behaviors of different countries.

[0093] In order to simulate the battery status and load changes under the preset working conditions, the simulation test tool can generate a voltage-current (VI) mapping table (also commonly referred to as a MAP table) based on the actual vehicle driving data and actual charging data, so as to accurately simulate the battery charging and discharging curve. In addition, it can not only provide static test conditions, but also simulate various dynamic conditions under the preset working conditions, such as high temperature fault, open circuit fault, short circuit fault and / or communication interruption.

[0094] Energy-saving operating conditions include, for example:

[0095] Scheduled wake-up condition, in which the battery management system wakes up at a fixed time after sleeping to check the battery cell voltage, battery cell temperature, SOC and other information, and then goes back to sleep after the check is completed;

[0096] Sleep balancing condition, in which the battery management system will issue a sleep balancing request based on the inconsistency of the battery cell state before it goes into sleep mode, so that when the battery management system goes into sleep mode, the slave control unit still works to perform balancing operations on the battery cells;

[0097] Fully dormant condition, in which the battery management system is in electrical dormancy, that is, a state of non-scheduled wake-up and non-dormant balance.

[0098] In sub-step S12, for each slave control unit being tested offline, the average power consumption per unit time under each preset working condition is calculated, and the reference power consumption is determined based on the average power consumption per unit time.

[0099] Specifically, for each slave control unit under test, its average power consumption per unit time can be calculated by the following formula:

[0100]

[0101] Among them, P i is the average power consumption per unit time of the slave control unit under the i-th preset working condition, t i1 is the test start time of the i-th preset working condition, t i2 is the test end time of the i-th preset working condition, V i (t) is the voltage of the slave control unit under the i-th preset working condition, I i (t) is the current of the slave control unit under the i-th preset operating condition.

[0102] For example, when testing the AC charging condition, the battery can be charged according to the AC charging voltage-current mapping table of the whole vehicle, and the current and voltage of each slave control unit are monitored and recorded at all times. Under the AC charging condition, the average power consumption P of each slave control unit per unit time is AC It can be calculated by the following formula:

[0103]

[0104] Among them, t AC1 is the start time of the AC charging test, t AC2 is the end time of the AC charging test, V AC (t) is the voltage across the slave control unit during the AC charging test, I AC(t) is the current of the slave control unit during the AC charging test.

[0105] For example, when testing the DC charging condition, the battery can be DC charged according to the DC charging voltage-current mapping table of the vehicle, and the current and voltage of each slave control unit are monitored and recorded at all times. Under the DC charging condition, the average power consumption P of each slave control unit per unit time is DC It can be calculated by the following formula:

[0106]

[0107] Among them, t DC1 is the start time of the DC charging test, t DC2 is the end time of the DC charging test, V DC (t) is the voltage across the slave control unit during the DC charging test, I DC (t) is the current of the slave control unit during the DC charging test.

[0108] For example, when testing the CLTC working condition, the battery can be discharged according to the voltage-current mapping table under the CLTC working condition, and the current and voltage of each slave control unit are constantly monitored and recorded. Under the CLTC working condition, the average power consumption P of each slave control unit per unit time is CLTC It can be calculated by the following formula:

[0109]

[0110] Among them, t CLTC1 is the start time of the CLTC discharge test, t CLTC2 is the end time of the CLTC discharge test, V CLTC (t) is the voltage across the slave unit during the CLTC discharge test, I CLTC (t) is the current of the slave unit during the CLTC discharge test.

[0111] For example, when testing the timed wake-up condition, the battery management system is controlled to enter the timed wake-up mode, that is, the slave control unit of the battery management system is woken up at regular intervals (for example, 1 hour or 2 hours) to detect the voltage, temperature, internal pressure value and other signals of the battery module and / or battery cell at this moment. After the detection is completed, the slave control unit goes to sleep again. When the slave control unit is woken up regularly, the average power consumption P of each slave control unit per unit time is RTC It can be calculated by the following formula:

[0112]

[0113] Among them, t RTC1 is the start time of the scheduled wake-up, t RTc2 is the end time of the scheduled wake-up, VRTC (t) is the voltage across the slave control unit during the timed wake-up period, I RTC (t) is the current of the slave unit during the timed wake-up period.

[0114] For example, when testing the dormant balancing condition, the battery management system is powered off and the dormant balancing requirement is periodically triggered so that the slave control unit performs the balancing operation. When the slave control unit performs the dormant balancing task, the average power consumption P of each slave control unit per unit time is Bal It can be calculated by the following formula:

[0115]

[0116] Among them, t Bal1 is the start time of sleep equilibrium, t Bal2 is the end time of sleep balance, V Bal (t) is the voltage across the slave unit during the sleep balance test, I Bal (t) is the current of the slave control unit during the sleep balance test.

[0117] For example, when testing the full sleep condition, the slave control unit may be powered off and put into sleep mode, and the average power consumption of each slave control unit per unit time may be calculated by the following formula:

[0118]

[0119] Among them, t Sleep1 is the start time of sleep equilibrium, t Sleep2 is the end time of sleep balance, V Sleep (t) is the voltage across the slave unit during the sleep balance test, I Sleep (t) is the current of the slave control unit during the sleep balance test.

[0120] As mentioned above, the average power consumption per unit time under each preset working condition is obtained for each slave control unit. To determine the reference power consumption, for example, the average power consumption per unit time of all tested slave control units can be averaged. Taking the DC charging working condition as an example, the average power consumption per unit time of 10 slave control units P is obtained through offline testing. DC , P DC ,…P DC10 The reference power consumption P of each slave control unit under DC charging conditions can be obtained by summing them and dividing by the number. ref,DC , that is, there exists:

[0121]

[0122] In the embodiment shown above, determining the reference power consumption of the slave control unit under energy-saving operating conditions involves consideration of different operating states. On the one hand, when the slave control unit is in an operating state (for example, the slave control unit performs a battery status monitoring operation or a voltage balancing operation when awakened), the first reference energy-saving power consumption of the slave control unit is determined. This reference value reflects the energy consumption level of the slave control unit when there is a task action in the energy-saving operation. On the other hand, when the slave control unit is in a non-operating state (i.e., completely dormant), the second reference energy-saving power consumption of the slave control unit is determined. In this state, the energy consumption of the slave control unit is minimized because most functions are turned off to achieve maximum energy savings.

[0123] In another embodiment, the specific operating state of the slave control unit under the energy-saving operating condition may not be distinguished, but the reference energy-saving power consumption may be directly calculated according to different operating condition categories. For example, when testing the timed wake-up condition, the total power consumption of the slave control unit over a period of time (including both the awakened period and the non-awakened period) may be calculated; when testing the sleep balance condition, the total power consumption of the slave control unit over a period of time (including both the sleep balance task execution period and the full sleep period) may be calculated. This method is particularly suitable for application scenarios that do not require very precise energy consumption control or require reduced computing overhead.

[0124] In sub-step S13, the reference power consumption of the slave control unit determined in an offline manner is stored in a calibration database.

[0125] Exemplarily, the calibration database may include:

[0126] An Internet database, which contains, for example, reference power consumption data of slave control units of different models in different countries or regions, so as to facilitate query and acquisition according to different requirements.

[0127] A local database of the vehicle and / or battery management system, which is used, for example, to store reference power consumption data that matches the slave control units actually used for a long time, so as to facilitate quick access and use.

[0128] In sub-step S14, in response to the battery state of charge estimation requirement and / or the state of charge correction requirement, the reference power consumption is retrieved from the calibration database of the battery management system locally and / or in the cloud. For example, in the absence of a network connection, key data stored locally can be accessed. By storing in the cloud, data can be shared between different vehicles or battery management systems, and real-time updating and maintenance of reference power consumption data is supported.

[0129] It should be noted that although step S1 is shown as including four sub-steps in this embodiment, in actual operation, not all sub-steps must be executed. For example, if the battery management system can directly retrieve reference power consumption data that is compatible with the current vehicle and battery status from a local or cloud database, step S14 can be executed directly, that is, these data are directly used for subsequent actual power consumption estimation and battery status monitoring. However, if the vehicle is in a new driving environment or a new model of battery management system is used, so there is no ready-made historical reference power consumption data available, then offline testing is required first. These results can then be used to update the local or cloud calibration database to provide the battery management system with the latest reference data.

[0130] Figure 6 Shows Figure 4 Flow chart of step S2 and step S3 of the method shown. In this embodiment, Figure 4 Step S2 of the method shown includes sub-steps S21 and S22, and step S3 includes sub-step S31.

[0131] In sub-step S21, the preset working condition of the slave control unit is identified by means of the battery management system. As described above, the preset working condition of the slave control unit can be identified by means of the battery management system by monitoring the current direction, current magnitude, connected charging interface type and voltage of the battery.

[0132] In sub-step S22, the actual working time of the slave control unit under the preset working conditions is recorded with the help of the timing chip of the battery management system.

[0133] For example, if you want to estimate the current state of charge, then for the time interval since the last estimated state of charge, identify all preset operating conditions involved in the slave control unit during this period, and record the actual working time of the slave control unit under each preset operating condition accordingly.

[0134] In sub-step S31, the actual power consumption of the slave control unit may be calculated by the following formula using the time weighted method:

[0135]

[0136] Among them, P act is the actual power consumption of the slave control unit, P ref,i is the reference power consumption of the slave control unit under the i-th preset working condition, t i is the actual working time of the slave control unit under the i-th preset working condition, m is the number of preset working conditions involved in the slave control unit within a predetermined time period, and N is the number of slave control units included in the battery management system.

[0137] For example, 5 minutes have passed since the last update of the battery state of charge. During these 5 minutes, the slave control unit operates in the DC charging condition and the driving discharge condition in turn, where the DC charging condition lasts for 4 minutes and the driving discharge condition lasts for 1 minute. The battery management system includes 10 slave control units. Therefore, the actual power consumption of the slave control unit in these 5 minutes can be calculated according to the following formula:

[0138] P act =10×(P ref,dC ×4+P ref,CLTC ×1)

[0139] Among them, P ref,DC is the reference power consumption of the slave control unit under DC charging conditions, P ref,CLTC is the reference power consumption of the slave control unit under driving discharge conditions (such as CLTC conditions), P act It is the actual power consumption of the slave control unit.

[0140] Figure 7 Shows Figure 4 Flowchart of step S2 and step S3 of the method shown. In this embodiment, step S2 includes sub-steps S21 and S23, and step S3 includes sub-steps S310-S320.

[0141] exist Figure 7 The specific implementation process of sub-steps S21 and S22 can be referred to Figure 6 The corresponding steps in are executed, which will not be repeated here for the sake of brevity.

[0142] In sub-step S23, the actual working conditions of the slave control unit under various preset working conditions within a predetermined time are collected. Specifically, the driving environment parameters (such as humidity, temperature, traffic flow, etc.) and vehicle state parameters (such as vehicle load, speed, acceleration, charge and discharge current, charge and discharge time, etc.) can be detected with the help of the vehicle's sensors. In addition, the Internet can be accessed with the help of corresponding communication interfaces, or external parameters (such as traffic conditions, the number of traffic lights on the driving section, weather conditions, etc.) can be received in real time based on vehicle-to-vehicle communication (V2V) or vehicle-to-infrastructure communication (V2I).

[0143] In sub-step S310, the reference power consumption is corrected according to the deviation between the actual working condition and the reference working condition used when the reference power consumption is determined in an offline manner. Specifically, a correction factor may be determined according to the deviation between the actual working condition and the reference working condition, and the reference power consumption may be corrected by superimposing the correction factor on the reference power consumption. For example, the correction factor may be determined based on the deviation between the actual working condition and the reference working condition in terms of temperature, humidity, vehicle load, and / or road conditions.

[0144] In one embodiment, if the actual operating condition information shows that the current ambient temperature is lower than the ambient temperature during the offline power consumption test, a correction factor a can be calculated based on the temperature deviation. Then, the correction factor a is added to the reference power consumption by the following formula:

[0145] P ref,CLTC ′=P ref,CLTC +P ref,CLTC ×a

[0146] Among them, P ref,CLTC is the uncorrected reference power consumption of the slave control unit under driving discharge conditions, P ref,CLTC ' is the corrected reference power consumption of the slave control unit under the driving discharge condition, and a is a correction factor related to temperature. For example, such correction increases the reference power consumption measured offline accordingly, because low temperature usually leads to reduced efficiency of components inside the slave control unit or increased heating demand, thereby increasing energy consumption.

[0147] In other embodiments, the correction factor may be determined based on a variety of other factors, such as humidity, vehicle load, speed, acceleration, charge and discharge current, road conditions, etc., and the combined impact of these factors on the reference power consumption may be weighted. Each factor may be assigned a different weight according to its actual impact on battery performance to ensure that the corrected reference power consumption more accurately reflects the energy consumption level of the slave control unit under different preset working conditions.

[0148] In sub-step S320, the actual power consumption may be determined based on the corrected reference power consumption. Figure 6 The sub-step S31 shown in is performed. For example, the actual power consumption of the slave control unit under each preset working condition can be calculated by multiplying the corrected reference power consumption by the actual working time under the preset working condition. Alternatively, the actual power consumption of the slave control unit can also be calculated according to the proportion of the working time of the slave control unit under each preset working condition within a predetermined time period.

[0149] When calculating the actual power consumption, the operating state and non-operating state of the slave control unit can also be discussed separately for the energy-saving operation condition, and the actual working time can be recorded for these two conditions and the corresponding actual power consumption can be calculated. Alternatively, this distinction can be omitted, and the actual working time can be recorded and the actual power consumption can be calculated according to the working mode category in each energy-saving operation condition.

[0150] Although the specific embodiments of the present application are described in detail herein, they are provided for the purpose of explanation only and should not be considered to limit the scope of the present application. Various substitutions, changes and modifications may be conceived without departing from the spirit and scope of the present application.

Claims

1. A method for estimating the state of charge of a battery (10), the method comprising the following steps: S1: obtaining a reference power consumption of a slave control unit of a battery management system (20) connected to the battery (10), wherein the reference power consumption is determined in an offline manner; S2: Acquiring actual operating condition information of the slave control unit in an actual operation scenario; S3: determining the actual power consumption of the slave control unit based on the reference power consumption of the slave control unit and the actual operating condition information; and S4: estimating the state of charge of the battery (10) based on the actual power consumption of the slave control unit.

2. The method according to claim 1, wherein: Step S4 includes: By means of a main control unit (BCU) of a battery management system (20), a rough state of charge of the battery (10) is estimated by time integration of the charge and discharge current of the battery (10) over a predetermined time period; and The rough state of charge is corrected based on the actual power consumption of the slave control unit to obtain the precise state of charge of the battery (10), and the precise state of charge is determined as the state of charge of the battery (10).

3. The method according to claim 1 or 2, wherein: The actual working condition information includes the actual working time of the slave control unit under each preset working condition within a predetermined time period. Step S3 includes: calculating the actual power consumption of the slave control unit by the following formula using a time weighted method: Among them, P act is the actual power consumption of the slave control unit, P ref,i is the reference power consumption of the slave control unit under the i-th preset working condition, t i is the actual working time of the slave control unit under the i-th preset working condition, m is the number of preset working conditions involved in the slave control unit within a predetermined time period, and N is the number of slave control units included in the battery management system (20).

4. The method according to claim 3, wherein: Step S2 comprises: using the battery management system (20) to monitor the current direction, current magnitude, type and voltage of the connected charging interface of the battery (10) to identify the preset working condition of the slave control unit, and using the timing chip of the battery management system (20) to record the actual working time of the slave control unit under the preset working condition.

5. The method according to any one of claims 1 to 4, wherein: The actual operating condition information includes the actual operating conditions of the slave control unit under each preset operating condition within a predetermined time period. Step S3 includes: correcting the reference power consumption according to the deviation between the actual operating conditions and the reference operating conditions used when determining the reference power consumption in an offline manner, and determining the actual power consumption based on the corrected reference power consumption.

6. The method according to claim 5, wherein: Step S3 includes: determining a correction factor according to a deviation between the actual working conditions and the reference working conditions, and correcting the reference power consumption by superimposing the correction factor on the reference power consumption, wherein the correction factor is determined based on the deviation between the actual working conditions and the reference working conditions in terms of temperature, humidity, vehicle load and / or road conditions.

7. The method according to any one of claims 3 to 6, wherein: The preset operating conditions include a normal operating condition and an energy-saving operating condition, in which the slave control unit is continuously connected, and in which the slave control unit is turned off or only periodically connected; and / or The preset operating conditions include: DC charging condition, AC charging condition, driving discharge condition, timed wake-up condition, sleep balance condition and complete sleep condition.

8. The method according to claim 7, wherein: The reference power consumption and / or actual power consumption of the slave control unit under the energy-saving operation condition is determined in the following manner: for the case where the slave control unit is in an operating state and a non-operating state under the energy-saving operation condition, the reference power consumption and / or actual power consumption of the slave control unit is determined separately.

9. The method according to any one of claims 1 to 8, wherein: Step S1 includes: Performing offline power consumption tests on the actual and / or other slave control units under a series of preset operating conditions; and For each slave control unit being tested offline, the average power consumption per unit time under each preset working condition is calculated, and the reference power consumption is determined based on the average power consumption per unit time.

10. The method according to claim 9, wherein: Step S1 includes: Simulating the battery state and / or load changes under each preset working condition by means of a simulation test tool, and for each preset working condition, measuring the current and voltage of the actual used and / or other slave control units by means of a high-precision current and voltage measurement unit within the test time; and For each slave control unit being tested offline, the average power consumption per unit time is calculated using the following formula: Among them, P i is the average power consumption per unit time of the slave control unit under the i-th preset working condition, t i1 is the test start time of the i-th preset working condition, t i2 is the test end time of the i-th preset working condition, V i (t) is the voltage of the slave control unit under the i-th preset working condition, I i (t) is the current of the slave control unit under the i-th preset operating condition.

11. The method according to any one of claims 1 to 10, wherein: Step S1 includes: storing the reference power consumption of the slave control unit determined in an offline manner in a calibration database locally in the battery management system (20) and / or in the cloud; and In response to a state of charge estimation requirement and / or a state of charge correction requirement of the battery (10), the reference power consumption is retrieved from a local and / or cloud calibration database of the battery management system (20).

12. A device (21) for estimating the state of charge of a battery (10), the device (21) comprising a memory and a processor, the memory storing computer program instructions, and when the computer program instructions are executed by the processor, the processor is capable of executing the method according to any one of claims 1 to 11.

13. A battery management system (20), comprising a master control unit (BCU) and a slave control unit, wherein the master control unit (BCU) comprises the device (21) according to claim 12.

14. The battery management system (20) according to claim 13, further comprising a human-machine interface (25), wherein the human-machine interface (25) is configured to: Outputting the state of charge of the battery (10) and / or outputting a rough state of charge that is not corrected based on the actual power consumption of the slave control unit; Adjusting the frequency of estimating the state of charge of the battery (10) based on user input data; and / or The type and number of preset operating conditions considered when calculating the actual power consumption of the slave control unit are adjusted according to the user's input data.

15. A battery system (1), comprising a battery (10) and a battery management system (20) according to claim 13 or 14 connected to the battery (10).

16. A vehicle comprising the device (21) according to claim 12, the battery management system (20) according to claim 13 or 14 and / or the battery system (1) according to claim 15. 17 . A computer program product having program code means, which are configured to cause a computer to execute the method according to claim 1 , when the computer program product is run on a computer or is stored on a computer-readable storage medium.

Images