CN115267573B - Voltage measurement method and device of battery management system - Google Patents
Voltage measurement method and device of battery management system Download PDFInfo
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- CN115267573B CN115267573B CN202211178664.8A CN202211178664A CN115267573B CN 115267573 B CN115267573 B CN 115267573B CN 202211178664 A CN202211178664 A CN 202211178664A CN 115267573 B CN115267573 B CN 115267573B
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/385—Arrangements for measuring battery or accumulator variables
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/374—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC] with means for correcting the measurement for temperature or ageing
Abstract
The invention provides a voltage measuring method and a voltage measuring device of a battery management system, wherein the method comprises the following steps: obtaining an initial voltage measurement based on the battery voltage signal and a reference voltage; receiving a set value of a voltage sampling integration period, and continuously obtaining a real-time temperature measurement value of the battery at a first time interval; calculating the ratio of the set value to the first time interval; determining the extraction interval of the continuously acquired real-time temperature measurement values according to the ratio, and obtaining the extraction value of the continuously acquired real-time temperature measurement values; determining the number of extraction values required for calculating the average value of the extraction values at one time according to the total number of the extraction values, and calculating the average value of the extraction values; calculating to obtain a voltage calibration value corresponding to the average value of each extracted value according to the average value of the extracted values of the real-time temperature measurement values, a voltage calibration calculation formula and calibration parameters; and calculating to obtain the calibrated voltage measurement value based on the voltage calibration value corresponding to the average value of each extracted value and the number of the average values of the extracted values.
Description
Technical Field
The invention mainly relates to the technical field of information, in particular to a voltage measuring method and device of a battery management system.
Background
The battery voltage is an important state parameter of the battery, particularly in the field of new energy electric vehicles, the lithium battery voltage is one of basic monitoring indexes, and the voltage monitoring is particularly important for risk early warning of the new energy electric vehicles in charging scenes, driving scenes or stopping scenes, so that higher requirements are provided for high-precision voltage measurement of battery components.
The application relates to the technical field of information, in particular to the technical field of a battery management system, and aims at a high-precision voltage measurement scene, and the environmental temperature is an important factor forming a voltage measurement precision error. Meanwhile, some extreme scenes exist inevitably, the environmental temperature of the battery during working is changed violently in a short time due to natural factors or human factors, and under the extreme scenes, how to eliminate the influence of the violent change of the environmental temperature on voltage measurement is particularly important for achieving high-precision voltage measurement of the battery assembly, and the method is also the key point for carrying out real-time risk early warning on the battery assembly.
Disclosure of Invention
The invention aims to provide a voltage measuring method and a voltage measuring device of a battery management system, which can realize accurate, quick and convenient measurement of the battery voltage of the battery management system.
In order to solve the technical problem, the invention provides a voltage measuring method of a battery management system, which comprises the following steps: obtaining an initial voltage measurement based on the battery voltage signal and a reference voltage; receiving a set value of a voltage sampling integration period, and continuously obtaining a real-time temperature measurement value of the battery at a first time interval; calculating the ratio of the set value to the first time interval; determining the extraction interval of the continuously acquired real-time temperature measurement values according to the ratio, and obtaining the extraction value of the continuously acquired real-time temperature measurement values; determining the number of extraction values required for calculating the average value of the once extraction values according to the total number of the extraction values, and calculating the average value of the corresponding extraction values; calculating to obtain a voltage calibration value corresponding to the average value of each extracted value according to the average value of the extracted values of the real-time temperature measurement values, a voltage calibration calculation formula and calibration parameters; and calculating to obtain a calibrated voltage measurement value corresponding to one voltage sampling integration period based on the voltage calibration value corresponding to the average value of each extracted value and the number of the average values of the extracted values.
In an embodiment of the invention, a ratio of the setting value of the voltage sampling integration period to the first time interval is (n-1) th power of 2, where n is a positive integer.
In an embodiment of the present invention, a product of the extraction interval of the continuously obtained real-time temperature measurement values, the number of extracted values required to calculate the average value of once extracted values, and the number of average values of extracted values is equal to a ratio of a set value of the voltage sampling integration period to the first time interval.
In an embodiment of the invention, when n =1, the decimation interval of the pair of continuously acquired real-time temperature measurements is the same as the first time interval; the number of the extraction values required for calculating the average value of the extraction values at one time is 1; the number of the average values of the extraction values is 1.
In an embodiment of the invention, when n is greater than or equal to 2 and less than or equal to 5, the extraction interval of the continuously acquired real-time temperature measurement values is the same as the first time interval; the number of the extraction values required for calculating the average value of the extraction values at one time is 1; the number of the average values of the extraction values is the power of (n-1) of 2.
In an embodiment of the present invention, when n is greater than or equal to 6 and less than or equal to 9, the extraction interval of the continuously obtained real-time temperature measurement values is the same as the first time interval; the number of the extraction values required for calculating the average value of the extraction values at one time is the power of (n-5) of 2; the number of the average values of the extraction values is 4 times of 2.
In one embodiment of the invention, when n is more than or equal to 10 and less than or equal to 15, the extraction interval of the continuously acquired real-time temperature measurement values is 2 (n-9) times of the first time interval; the number of the extraction values required for calculating the average value of the extraction values at one time is the power of 4 of 2; the number of the average values of the extraction values is 4 times of 2.
In an embodiment of the present invention, the voltage calibration calculation formula is:
wherein the calibration parameters include:
is the initial voltage measurement, N is the quantized bit width of the initial voltage measurement,
offset errors are compensated for temperature dependent analog to digital converters,
for temperature dependent analog to digital converter gain errors,
MA is the ratio of the span of the voltage signal to the reference voltage, which is a temperature-dependent reference voltage.
In an embodiment of the present invention, the reference voltage includes a reference voltage provided by a zener voltage or a reference voltage of a bandgap voltage type.
The present invention also provides a voltage measuring device of a battery management system, including: a base measurement module configured to: obtaining an initial voltage measurement based on the battery voltage signal and a reference voltage; the controller is used for controlling the set value of the transmission voltage sampling integration period and the calibration parameter of the transmission voltage measurement; a sliding decimating average filtering module configured to: receiving a set value of a voltage sampling integration period, and continuously obtaining a real-time temperature measurement value of the battery at a first time interval; calculating the ratio of the set value to the first time interval; determining the extraction interval of the continuously acquired real-time temperature measurement values according to the ratio, and obtaining the extraction value of the continuously acquired real-time temperature measurement values; determining the number of extraction values required for calculating the average value of the once extraction values according to the total number of the extraction values, and calculating the average value of the corresponding extraction values; a voltage measurement calibration engine configured to: calculating to obtain a voltage calibration value corresponding to the average value of each extracted value according to the average value of the extracted values of the real-time temperature measurement values, a voltage calibration calculation formula and calibration parameters; a second average filtering module configured to: calculating to obtain a calibrated voltage measurement value corresponding to a voltage sampling integration period based on the voltage calibration value corresponding to the average value of each extraction value and the number of the average values of the extraction values; and the basic measurement module, the controller, the voltage measurement calibration engine, the sliding extraction average filtering module and the second average filtering module realize data and instruction transmission through network communication.
In one embodiment of the invention, the base measurement module includes a delta-sigma analog-to-digital converter and an integrator.
Compared with the prior art, the invention has the following advantages: according to the technical scheme, the voltage measurement precision under the scene of extreme temperature change can be remarkably improved, the high-precision voltage measurement requirement of the power battery of the new energy automobile is met, the detection reliability and the risk early warning reliability of the power battery of the new energy automobile under the extreme environment can be improved. Meanwhile, the scheme of the application can realize low cost, low time delay and convenient engineering.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the principle of the application. In the drawings:
fig. 1 is a flowchart of a voltage measurement method of a battery management system according to an embodiment of the present application.
Fig. 2 is a schematic diagram of a voltage measurement device of a battery management system according to an embodiment of the present application.
Fig. 3 is a schematic diagram of a part of a voltage measuring device of a battery management system according to an embodiment of the present application.
Fig. 4 is a schematic process diagram of an implementation process of a voltage measurement method of a battery management system according to an embodiment of the present application.
Fig. 5 is a schematic process diagram of an implementation process of a voltage measurement method of a battery management system according to an embodiment of the present application.
Fig. 6 is a schematic process diagram of an implementation process of a voltage measurement method of a battery management system according to an embodiment of the present application.
Fig. 7 is a schematic process diagram of an implementation process of a voltage measurement method of a battery management system according to an embodiment of the present application.
Fig. 8 is a schematic diagram of a cell voltage measurement result of an embodiment.
Fig. 9 is a schematic diagram of measurement results of a voltage measurement method and device of a battery management system according to an embodiment of the present application.
FIG. 10 is an I-V (current-voltage) curve of a Zener tube of an embodiment of the present application at various temperatures.
Detailed Description
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the description of the embodiments will be briefly introduced below. It is obvious that the drawings in the following description are only examples or embodiments of the application, from which the application can also be applied to other similar scenarios without inventive effort for a person skilled in the art. Unless otherwise apparent from the context, or otherwise indicated, like reference numbers in the figures refer to the same structure or operation.
As used in this application and the appended claims, the terms "a," "an," "the," and/or "the" are not intended to be inclusive in the singular, but rather are intended to be inclusive in the plural unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" are intended to cover only the explicitly identified steps or elements as not constituting an exclusive list and that the method or apparatus may comprise further steps or elements.
The relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, so that the scope of the present application is not to be construed as being limited. Further, although the terms used in the present application are selected from publicly known and used terms, some of the terms mentioned in the specification of the present application may be selected by the applicant at his or her discretion, the detailed meanings of which are described in relevant parts of the description herein. Further, it is required that the present application is understood not only by the actual terms used but also by the meaning of each term lying within.
Flow charts are used herein to illustrate operations performed by systems according to embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in the exact order in which they are performed. Rather, various steps may be processed in reverse order or simultaneously. At the same time, other operations are either added to or removed from these processes.
Embodiments of the present application describe voltage measurement methods and apparatus for battery management systems.
The voltage measuring method of the Battery Management System is applied to a vehicle Management System (BMS), and the System realizes real-time monitoring of parameters such as voltage, temperature and impedance of a power Battery of a new energy automobile. Also, given the complexity of the onboard environment, the drastic changes in temperature can present challenges to the accuracy of the voltage measurement parameters of the battery management system.
Fig. 1 is a flowchart of a voltage measurement method of a battery management system according to an embodiment of the present application.
Referring to fig. 1, a voltage measurement method of a Battery Management System (BMS) includes, step 101, obtaining an initial voltage measurement value based on a Battery voltage signal and a reference voltage; step 102, receiving a set value of a voltage sampling integration period, and continuously obtaining a real-time temperature measurement value of a battery at a first time interval; step 103, calculating the ratio of the set value to the first time interval; 104, determining the extraction interval of the continuously acquired real-time temperature measurement values according to the ratio, and obtaining the extraction value of the continuously acquired real-time temperature measurement values; step 105, determining the number of extraction values required for calculating the average value of the extraction values once according to the total number of the extraction values, and calculating the average value of the corresponding extraction values; step 106, calculating to obtain a voltage calibration value corresponding to the average value of each extracted value according to the average value of the extracted values of the real-time temperature measurement values, a voltage calibration calculation formula and calibration parameters; and 107, calculating to obtain a calibrated voltage measurement value corresponding to one voltage sampling integration period based on the voltage calibration value corresponding to the average value of each extracted value and the number of the average values of the extracted values.
Fig. 2 is a schematic diagram illustrating a voltage measurement device of a battery management system according to an embodiment of the present application. Fig. 3 is a schematic diagram of a part of a voltage measuring device of a battery management system according to an embodiment of the present application.
Specifically, referring to fig. 2, the voltage measurement device 200 of the battery management system includes, for example, a basic measurement module 201, a controller 210 (i.e., MCU), and a voltage measurement calibration module 203. The battery management system may further include a memory (memory) connected to the controller and receiving a control signal from the controller to transmit and receive stored data.
Referring to fig. 3, the voltage measurement calibration module 203 includes a sliding decimation averaging filter module, a voltage measurement calibration engine, and a second averaging filter module.
And the basic measurement module, the controller, the voltage measurement calibration engine, the sliding extraction average filtering module and the second average filtering module realize data and instruction transmission through network communication.
In some embodiments, the base measurement module 201 is configured to obtain an initial voltage measurement based on the battery voltage signal and a reference voltage.
In some embodiments, the reference voltage comprises a reference voltage provided by a zener voltage or a bandgap voltage type of reference voltage. A buried Zener (Zener) voltage reference can provide better stability over temperature, time, and other operating conditions. However, both the bandgap voltage reference and the zener voltage reference are affected by abrupt changes in ambient temperature, and voltage measurement errors are introduced. Therefore, the numerical value measured based on the built-in voltage reference is optimized, and the measurement error caused by sudden change of the environmental temperature is reduced, which is very important for improving the voltage measurement precision.
Fig. 10 is an I-V (current-voltage) curve of a ziner according to an embodiment of the present application at different temperatures (high, low and typical). With a continuous time Delta Sigma ADC, a longer sampling and integration period means lower noise in the measurement results and higher measurement accuracy. Therefore, in order to obtain higher measurement accuracy, a longer sampling and integration period is usually set on the premise of meeting the system requirement of voltage measurement response sensitivity. Meanwhile, if a temperature is changed drastically in a long sampling and integration period, the voltage measurement accuracy in the period is seriously affected. Under the conditions of a longer sampling integration period and a faster temperature change, the voltage measurement error is far beyond the high-precision measurement requirement which needs to be met, for example, the high-precision measurement requirement of an error range +/-2 mV is met.
In some embodiments, the base measurement module includes a Delta-Sigma analog-to-digital converter (Delta-Sigma ADC) and an integrator. Specifically, the Delta-Sigma ADC is used for comparing a reference voltage with the voltage of the battery component of the tested object, performing analog-to-digital conversion, outputting bit stream data to the integrator, and the integrator is used for integrating the bit stream data to obtain initial battery voltage measurement data, namely initial voltage measurement values.
Then, for the initial voltage measurement value, it needs to be calibrated by a calibration formula and calibration parameters pre-configured in the Memory to obtain a voltage measurement value with higher accuracy, and further includes calibrating the influence of performance difference of ADCs (analog-to-digital converters) between different batches of chips on the voltage measurement data.
As previously described, at step 102, a set point for a voltage sample integration period is received and real-time temperature measurements of the battery are continuously obtained at first time intervals.
In some embodiments, the ratio of the set value of the voltage sampling integration period to the first time interval is 2 to the power of (n-1), i.e., 2^ (n-1), where n is a positive integer. The voltage sampling integration period may also be attributed to the calibration parameters. And obtaining a calibrated voltage measurement value corresponding to each voltage sampling integration period.
The first Time interval may also be referred to as a Temperature Sample Integration period or a Temperature value Sample Integration Time/Sample. Real-time temperature measurements are obtained, for example, by temperature sensors. The real-time temperature measurement of the battery may refer to a plurality of single batteries in a battery pack (battery pack), or referred to as a real-time temperature measurement of a battery cell.
In order to make the technical scheme of the application more clearly understood, the technical scheme of the application is combined with specific numerical parameters. The first time interval is, for example, 8.192ms (milliseconds).
In some embodiments, the product of the decimation interval for the continuously acquired real-time temperature measurements, the number of decimated values required to calculate the average of one decimated value, and the number of average of decimated values is equal to the ratio of the set value of the voltage sample integration period to the first time interval.
Fig. 7 is a schematic process diagram of an implementation process of a voltage measurement method of a battery management system according to an embodiment of the present application.
In step 103, a ratio of the set value to the first time interval is calculated.
In some embodiments, when n is greater than or equal to 10 and less than or equal to 15, the ratio of the set value of the voltage sampling integration period to the first time interval is 2 9 、2 10 、…、2 13 Or 2 14 。
In step 104, the extraction interval of the continuously acquired real-time temperature measurement values is determined according to the ratio, and the extraction value of the continuously acquired real-time temperature measurement values is obtained. For example, when the ratio of the setting value of the voltage sampling integration period to the first time interval is 2 14 (n = 15), the decimation interval for the continuously acquired real-time temperature measurements is determined to be 2 (n-9) times the first time interval, i.e., 6, 64 times 2. I.e., one value is extracted every 64 consecutive acquired real-time temperature measurements as a value extracted for the consecutive acquired real-time temperature measurements. 2 14 = 16384, when the first time interval or the temperature sampling integration period is 8.192ms, the set value of the voltage sampling integration period is 2 14 * 8.192ms = 134217.728ms. There are 16384 consecutive real-time temperature measurements (e.g., t) taken during a voltage sampling integration period 1 、t 2 、…、t 16384 ）。
In FIG. 7, M is 16384, T [ 2 ]] = T[16384]Denotes a previous Voltage Integration Time/Sample Integration period V [ k-2 ]]To V [ k-1]The last real-time temperature measurement. At the current voltage sampling integration period V [ k-1 ]]To Vk](i.e., slide to next cycle), real-time temperature measurements are taken from T1]Start to recount, T [1 ]]、T[2] 、…、T[16384]Is the aforementioned t 1 、t 2 、…、t 16384 . The S value in fig. 7 is taken to be 64. In the embodiment denoted in FIG. 7, for example from T [1 ]]、T[2] 、…、T[64]Extracting T [64 ]]As a first, real-time temperature measurement, from T65]、T[66] 、…、T[128]Extract T [128 ]]As the first real-time temperature measurement, and so on. This is the process of the decimation process in fig. 7.
In step 105, the number of the extraction values required for calculating the average value of the extraction values at one time is determined according to the total number of the extraction values, and the average value of the corresponding extraction values is calculated. For example, when n =15 and the decimation interval for the continuously acquired real-time temperature measurements is 64 times the first time interval, the total number of decimation values is 2 14 Divide by 64 to 256 (e.g., ts) 1 、ts 2 、…、ts 256 ). Based on the total number of the extracted values, the number of extracted values required for calculating the average value of the extracted values once is determined to be the power of 4 of 2, namely 16, and the corresponding average value of the extracted values is calculated (for example, tsa 1 、tsa 2 、…、tsa 16 Wherein, tsa 1 = (ts 1 + ts 2 +…+ ts 16 )/16，tsa 2 、…、tsa 16 And so on). This is the process of the pre-averaging process in fig. 7. Each pre-averaging process needs to call a sliding extraction average filtering module.
In step 106, a voltage calibration value corresponding to the average value of each extracted value is calculated according to the average value of the extracted values of the real-time temperature measurement values, the voltage calibration calculation formula and the calibration parameters. In fig. 7, this corresponds to the process of iteratively invoking the calibration engine.
In some embodiments, the voltage calibration calculation formula is:
the calibration parameters include:
NR is the quantized bit width of the initial voltage measurement,
offset errors are compensated for temperature dependent analog to digital converters,
for temperature dependent analog to digital converter gain errors,
for a temperature-dependent reference voltage, MA is the ratio of the span of the voltage signal to the reference voltage.
Regarding the range of the voltage signal, if the measurement range of the voltage signal is 1.2V to 6V, the range of the voltage signal is 4.8V. In voltage calibration calculation formulaTThe value, in this case the average of the extracted values of the real-time temperature measurements (namely tsa) 1 、tsa 2 、…、tsa 16 ）。
Next, in step 107, a calibrated voltage measurement value corresponding to one voltage sampling integration period is calculated based on the voltage calibration value corresponding to the average value of each extracted value and the number of the average values of the extracted values. For example, when n =15 and the decimation interval for continuously acquired real-time temperature measurements is 64 times the first time interval, the total number of decimation values is 2 14 Dividing by 64, 256 are obtained. The number of the extracted values required for calculating the average value of the extracted values at one time is 16, which is the power of 4 of 2, so that the number of the average values of the extracted values obtained is 16. Voltage corresponding to average value of extracted valueThe calibration value is also 16 (e.g., including V1, V2, \ 8230;, V16, labeled V _ calibrration [1 ] in FIG. 7)]、V_calibration[2]、…、V_calibration[16]) And a voltage measurement calibration engine is required to be called for the calculation of the voltage calibration value corresponding to the average value of each extracted value. And carrying out average operation on the voltage calibration value corresponding to the average value of the 16 extraction values to obtain a calibrated voltage measurement value V _ Result corresponding to one voltage sampling integration period. In fig. 7, the process of the post-averaging processing is specifically realized by the operation of the second averaging and filtering module in fig. 3.
Referring to the implementation process of the voltage measurement method of the battery management system when n is more than or equal to 10 and less than or equal to 15, when n is more than or equal to 6 and less than or equal to 9, the extraction interval of the continuously acquired real-time temperature measurement values is the same as the first time interval; the number of the extraction values required for calculating the average value of the extraction values at one time is the power of 2 (n-5); the number of the average values of the extraction values is 4 times of 2.
When n is more than or equal to 6 and less than or equal to 9, the ratio of the set value of the voltage sampling integration period to the first time interval is 2 5 、2 6 、2 7 Or 2 8 。
Fig. 6 is a schematic process diagram of an implementation process of a voltage measurement method of a battery management system according to an embodiment of the present application. In fig. 6, since the extraction interval for the continuously acquired real-time temperature measurement values is the same as the first time interval, the real-time temperature measurement value acquired each time is directly taken as the value of the average value of the extraction values, and thus the extraction process is not particularly shown. The number of decimation values required for calculating the average value of the decimation values once is the (N-5) power of 2, i.e., the N value in fig. 6, for example, when N =9, N is the 4 power of 2, i.e., 16, i.e., the number of decimation values required for calculating the average value of the decimation values once is 16; when N =8, N is 3 powers of 2, i.e. 8, i.e. the number of decimation values required to calculate the average value of one decimation value is 8. The pre-averaging process is implemented by, for example, the operation of the sliding decimation averaging filter module in fig. 3. The subsequent implementation process is described with reference to fig. 7. The value of M in FIG. 6 is 2 5 、2 6 、2 7 Or 2 8 I.e. 32, 64, 128 or256。
Similarly, when n is greater than or equal to 2 and less than or equal to 5, the extraction interval of the continuously acquired real-time temperature measurement values is the same as the first time interval; the number of the extraction values required for calculating the average value of the once extraction values is 1; the number of the average values of the extraction values is the power of (n-1) of 2.
When n is more than or equal to 2 and less than or equal to 5, the ratio of the set value of the voltage sampling integration period to the first time interval is 2 1 、2 2 、2 3 Or 2 4 。
Fig. 5 is a schematic process diagram of an implementation process of a voltage measurement method of a battery management system according to an embodiment of the present application. In fig. 5, since the extraction interval for the continuously acquired real-time temperature measurement values is the same as the first time interval and the number of extracted values required to calculate the average value of one extracted value is 1, the extraction process and the pre-averaging process are not particularly shown. The number of decimation values required to calculate the average of one decimation value is 1, in other words, the average of one decimation value is the decimation value itself. For the sake of uniform presentation of the claims of this application, the foregoing definitions are made. The value of M in FIG. 5 is 2 1 、2 2 、2 3 Or 2 4 I.e. 2, 4, 6 or 8. The procedure of invoking the calibration engine and the procedure of post-averaging in subsequent iterations in fig. 5 are similar to fig. 6 or fig. 7, and may be implemented by the operations of the voltage measurement calibration engine and the second averaging filter module in fig. 3, respectively.
When n =1, the decimation interval for the continuously acquired real-time temperature measurements is the same as the first time interval; the number of the extraction values required for calculating the average value of the once extraction values is 1; the number of the average values of the extraction values is 1.
When n =1, the ratio of the set value of the voltage sampling integration period to the first time interval is 2 0 I.e. 1. At this time, the set value of the voltage sampling integration period is equal to the first time interval. I.e. the Voltage Integration Time/Sample is equal to the Temperature Integration Time/Sample. For example, when the temperature sampling integration period is 8.192ms, the voltage sampling integration periodIs also 8.192ms.
Fig. 4 is a schematic process diagram of an implementation process of a voltage measurement method of a battery management system according to an embodiment of the present application. In fig. 4, the decimation interval for the continuously acquired real-time temperature measurements is the same as the first time interval; the number of the extraction values required for calculating the average value of the extraction values at one time is 1; the number of the average values of the extraction values is 1, and actually, the voltage sampling integration period is equal to the temperature sampling integration period, so that each real-time temperature measurement value can be directly used for calculating the battery voltage calibration calculation, namely, the voltage calibration calculation formula is substituted, and the calibrated voltage measurement value corresponding to one voltage sampling integration period is obtained by combining the corresponding calibration parameters. That is, at this time, in the voltage measurement process of a single period, the voltage measurement calibration engine needs to be called only once, so that post-averaging processing of calibration data is not needed, and the calibrated value is directly output as the final voltage measurement result. The illustration in fig. 4 is also simplified accordingly, and the process of invoking the calibration engine is not shown again.
When n takes other positive integer values, the battery voltage measurement and calibration process can be performed with reference to the scheme implementation process.
Fig. 9 is a schematic diagram of measurement results of a voltage measurement method and device of a battery management system according to an embodiment of the present application. Fig. 8 is a schematic diagram of a cell voltage measurement result of an embodiment. The scheme corresponding to fig. 8 is, for example, that the voltage measurement calibration module only includes the voltage measurement calibration engine, and does not include the sliding decimation filtering module and the second averaging filtering module.
Referring to fig. 8 and 9, in a similar temperature variation environment (T), before the implementation of the embodiment of the present application, the voltage measurement Error (Error) is close to 12mV, and after the implementation of the embodiment of the present application, the voltage measurement Error is about 1.33mV, which meets the high-precision voltage measurement requirement of ± 2 mV.
The technical scheme of the application provides a voltage measurement method of a battery management system, which can significantly improve the voltage measurement precision of a BMS and realize low cost and low complexity under an extreme scene of severe temperature change, and can also be called as a voltage measurement temperature compensation method of the battery management system (temperature compensation refers to compensation of errors caused by temperature fluctuation so as to reduce error values).
Compared with the technical solution of the present application, if the voltage measuring device of the battery management system only includes the front averaging filter or only includes the rear averaging filter, a large resource and power consumption cost is faced when the engineering is implemented.
Specifically, if only the front-stage averaging filter is adopted (the second averaging filter module is removed in fig. 3, and the sliding extraction averaging filter module is changed into the averaging filter), all real-time temperature measurement values within the whole voltage sampling integration time are averaged and filtered, so that a temperature average value is obtained within the whole voltage sampling integration time and is used for temperature compensation calculation in the voltage measurement calibration engine, and the voltage measurement accuracy under the scene of rapid temperature change can be greatly improved; only by adopting a post-stage averaging filter (removing the sliding extraction averaging filtering module in fig. 3), voltage measurement calibration calculation is performed on all real-time temperature measurement values within the whole voltage sampling integration time, and then averaging filtering is performed on all voltage measurement calibration values calculated within the whole voltage sampling integration time, so that the voltage measurement accuracy under the scene of rapid temperature change can be greatly improved.
However, for the case that the voltage sampling integration period is long, for example, one voltage sampling integration period corresponds to hundreds, thousands, or 16384 temperature sampling point values, in this case, the voltage measurement device of the battery management system only includes the front averaging filter or only includes the rear averaging filter, which will face a large resource and power consumption cost, and is not favorable for the engineering implementation of the scheme.
Specifically, if a pre-filter is adopted, a maximum of 16384 temperature sampling point values are required to be supported for summation and average value calculation; if the post-filter is adopted, the voltage measurement calibration engine needs to be called iteratively for calibration calculation for each temperature sampling point, at most 16384 engine calls need to be supported, and then at most 16384 calibration values need to be supported for summation and average calculation.
Therefore, no matter the method of adding the pre-filter or the post-filter independently is adopted, at least 16384 bit Flip-Flop (Flip-Flop) needs to be added, which brings great challenges to the chip area during engineering implementation; especially, in the method of adding the post-filter separately, since it needs to call the calibration engine iteratively up to 16384 times, and the processing delay 16384x8 μ s (estimated value of processing delay of single calibration) =131.072ms is additionally added, the processing delay and power consumption are greatly increased.
According to the technical scheme, the front sliding extraction average filtering module and the rear second average filtering module are used in a combined mode, and the sliding extraction average filtering process and the second average filtering process are carried out, so that the voltage measurement precision under the scene of rapid temperature change is greatly improved, and the feasibility of the scheme in engineering implementation is also improved.
Table 1 below is a statistical table of logic resources that need to be consumed when the voltage measurement device of the battery management system according to the embodiment of the present application is implemented in an engineering manner. The voltage value bit width (referred to as binary bit width) is, for example, 16. The consumption of the added logic resource is low compared with the consumption of ten thousand or more Flip-flops (triggers) of the battery management system. In addition, in the logic operation, since the division can adopt a mode of dividing by a power of 2, only simple addition and shift truncation operation processing are needed. Regarding the delay of the processing procedure, since the calibration engine can be executed by serial iteration, the processing delay needs to be increased by 16 times x8 μ s =128 μ s, and thus it can be seen that the processing delay is also extremely small, especially compared with the aforementioned 131.072ms, by several orders of magnitude.
TABLE 1
According to the voltage measurement method and device of the battery management system, the voltage measurement precision under the scene of extreme temperature change can be remarkably improved, the requirement for high-precision voltage measurement of the new energy automobile power battery is met, the detection reliability and risk early warning reliability of the new energy automobile power battery under the extreme environment can be improved. In addition, the scheme of the application can also realize low cost, low time delay and convenient engineering of the scheme implementation.
According to the technical scheme, the calculation and calibration modes can be flexibly selected according to the requirement on the measurement accuracy, for example, in some industrial scale (industrial application) scenes, the accuracy of the measurement on the voltage of the battery is lower than the requirement of +/-2 mV, so that the n value can be set according to the requirement, the calculation process is simplified, and the comprehensive performance of a corresponding system is improved.
Aspects of the present application may be embodied entirely in hardware, entirely in software (including firmware, resident software, micro-code, etc.) or in a combination of hardware and software. The above hardware or software may be referred to as "data block," module, "" engine, "" unit, "" component, "or" system. The processor may be one or more Application Specific Integrated Circuits (ASICs), digital Signal Processors (DSPs), digital signal processing devices (DAPDs), programmable Logic Devices (PLDs), field Programmable Gate Arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, or a combination thereof. Furthermore, aspects of the present application may be represented as a computer product, including computer readable program code, embodied in one or more computer readable media. For example, computer-readable media can include, but are not limited to, magnetic storage devices (e.g., hard disk, floppy disk, magnetic tape \8230;), optical disks (e.g., compact disk CD, digital versatile disk DVD \8230;), smart cards, and flash memory devices (e.g., card, stick, key drive \8230;).
The computer-readable medium may comprise a propagated data signal with the computer program code embodied therein, for example, on a baseband or as part of a carrier wave. The propagated signal may take any of a variety of forms, including electromagnetic, optical, and the like, or any suitable combination. The computer readable medium can be any computer readable medium that can communicate, propagate, or transport the program for use by or in connection with an instruction execution system, apparatus, or device. Program code on a computer readable medium may be propagated over any suitable medium, including radio, electrical cable, fiber optic cable, radio frequency signals, or the like, or any combination of the preceding.
Similarly, it should be noted that in the preceding description of embodiments of the application, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the embodiments. This method of disclosure, however, is not intended to imply that more features are required than are expressly recited in the claims. Indeed, the embodiments may be characterized as having less than all of the features of a single embodiment disclosed above.
Where numerals describing the number of components, attributes or the like are used in some embodiments, it is to be understood that such numerals used in the description of the embodiments are modified in some instances by the modifier "about", "approximately" or "substantially". Unless otherwise indicated, "about", "approximately" or "substantially" indicates that the number allows a variation of ± 20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximations that may vary depending upon the desired properties of the individual embodiments. In some embodiments, the numerical parameter should take into account the specified significant digits and employ a general digit preserving approach. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the range are approximations, in the specific examples, such numerical values are set forth as precisely as possible within the scope of the application.
Although the present application has been described with reference to the present specific embodiments, it will be appreciated by those skilled in the art that the above embodiments are merely illustrative of the present application and that various equivalent changes or substitutions may be made without departing from the spirit of the application, and therefore, it is intended that all changes and modifications to the above embodiments within the spirit of the application fall within the scope of the claims of the application.
Claims (12)
1. A voltage measurement method of a battery management system includes the following steps:
obtaining an initial voltage measurement based on the battery voltage signal and a reference voltage;
receiving a set value of a voltage sampling integration period, and continuously obtaining a real-time temperature measurement value of the battery at a first time interval;
calculating the ratio of the set value to the first time interval;
determining extraction intervals of the continuously acquired real-time temperature measurement values according to the ratio, and obtaining extraction values of the continuously acquired real-time temperature measurement values;
determining the number of extraction values required for calculating the average value of the extraction values at one time according to the total number of the extraction values, and calculating the average value of the corresponding extraction values;
calculating a voltage calibration value corresponding to the average value of each extracted value according to the average value of the extracted values of the real-time temperature measurement value, a voltage calibration calculation formula and a calibration parameter;
calculating to obtain a calibrated voltage measurement value corresponding to a voltage sampling integration period based on the voltage calibration value corresponding to the average value of each extraction value and the number of the average values of the extraction values;
wherein, the voltage calibration calculation formula is as follows:
the calibration parameters include: VM raw For the initial voltage measurement, N is the quantized bit width of the initial voltage measurement, offset (T) is the temperature dependent ADC Offset error, gain (T) is the temperature dependent ADC Gain error, V ref (T) is a reference voltage related to temperature, and MA is a ratio of a span of the voltage signal to the reference voltage.
2. The voltage measurement method of the battery management system according to claim 1, wherein a ratio of the set value of the voltage sampling integration period to the first time interval is 2 to the (n-1) th power, n being a positive integer.
3. The voltage measuring method of a battery management system according to claim 1, wherein the product of the extraction interval of the continuously obtained real-time temperature measurement values, the number of extraction values required to calculate the average value of extraction values at one time, and the number of average values of extraction values is equal to the ratio of the set value of the voltage sampling integration period to the first time interval.
4. The voltage measurement method of a battery management system according to claim 2, wherein when n =1,
the decimation interval for the continuously acquired real-time temperature measurements is the same as the first time interval; the number of the extraction values required for calculating the average value of the extraction values at one time is 1; the number of the average values of the extraction values is 1.
5. The voltage measuring method of a battery management system according to claim 2, wherein when 2. Ltoreq. N.ltoreq.5,
the extraction interval for the continuously acquired real-time temperature measurements is the same as the first time interval; the number of the extraction values required for calculating the average value of the extraction values at one time is 1; the number of the average values of the extraction values is the power of (n-1) of 2.
6. The voltage measuring method of a battery management system according to claim 2, wherein when 6. Ltoreq. N.ltoreq.9,
the extraction interval for the continuously acquired real-time temperature measurements is the same as the first time interval; the number of the extraction values required for calculating the average value of the extraction values at one time is the power of 2 (n-5); the number of the average values of the extraction values is 4 times of 2.
7. The voltage measuring method of a battery management system according to claim 2, wherein when 10. Ltoreq. N.ltoreq.15,
the decimation interval for the continuously acquired real-time temperature measurements is 2 (n-9) times the first time interval; the number of the extraction values required for calculating the average value of the extraction values at one time is the power of 4 of 2; the number of the average values of the extracted values is 4 th power of 2.
8. The voltage measurement method of a battery management system according to claim 1, wherein the reference voltage includes a reference voltage provided by a zener voltage or a reference voltage of a bandgap voltage type.
9. A voltage measurement device of a battery management system, comprising:
a base measurement module configured to: obtaining an initial voltage measurement based on the battery voltage signal and a reference voltage;
the controller is used for controlling the set value of the transmission voltage sampling integration period and the calibration parameter of the transmission voltage measurement;
a sliding decimating average filtering module configured to:
receiving a set value of a voltage sampling integration period, and continuously obtaining a real-time temperature measurement value of the battery at a first time interval;
calculating the ratio of the set value to the first time interval;
determining extraction intervals of the continuously acquired real-time temperature measurement values according to the ratio, and obtaining extraction values of the continuously acquired real-time temperature measurement values;
determining the number of extraction values required for calculating the average value of the extraction values at one time according to the total number of the extraction values, and calculating the average value of the corresponding extraction values;
a voltage measurement calibration engine configured to:
calculating to obtain a voltage calibration value corresponding to the average value of each extracted value according to the average value of the extracted values of the real-time temperature measurement values, a voltage calibration calculation formula and calibration parameters;
a second average filtering module configured to:
calculating to obtain a calibrated voltage measurement value corresponding to a voltage sampling integration period based on the voltage calibration value corresponding to the average value of each extraction value and the number of the average values of the extraction values;
the basic measurement module, the controller, the voltage measurement calibration engine, the sliding extraction average filtering module and the second average filtering module realize data and instruction transmission through network communication;
wherein the voltage calibration calculation formula is as follows:
the calibration parameters include: VM raw For the initial voltage measurement, N is the quantized bit width of the initial voltage measurement, offset (T) is the temperature dependent ADC Offset error, gain (T) is the temperature dependent ADC Gain error, V cref (T) is a temperature dependent reference voltage, and MA is a ratio of the span of the voltage signal to the reference voltage.
10. The battery management system voltage measurement device of claim 9, wherein the base measurement module comprises a delta-sigma analog-to-digital converter and an integrator.
11. The voltage measurement device of the battery management system according to claim 9, wherein a ratio of the set value of the voltage sampling integration period to the first time interval is 2 to the (n-1) th power, n being a positive integer.
12. The voltage measurement device of the battery management system according to claim 9, wherein the product of the decimation interval of the continuously acquired real-time temperature measurement values, the number of decimation values required to calculate the average value of one decimation value, and the number of average values of the decimation values is equal to the ratio of the set value of the voltage sampling integration period to the first time interval.
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Effective date of registration: 20230814 Address after: Building 39, No. 700 Wanrong Road, Jing'an District, Shanghai, 200072 Patentee after: Shanghai Da'en Xinyuan Microelectronics Co.,Ltd. Address before: Room 201, Building A12, South Safety Technology Industrial Park, Lijiang Road, Xuzhou High-tech Industrial Development Zone, Xuzhou City, Jiangsu Province, 221000 Patentee before: Datang NXP Semiconductors (Xuzhou) Co.,Ltd. |