CN116859260A

CN116859260A - Battery parameter calculation method, device and system

Info

Publication number: CN116859260A
Application number: CN202310902061.6A
Authority: CN
Inventors: 朱坤旭; 詹福春
Original assignee: Xinxiang Technology Hefei Co ltd
Current assignee: Xinxiang Technology Hefei Co ltd
Priority date: 2023-07-21
Filing date: 2023-07-21
Publication date: 2023-10-10

Abstract

A battery parameter calculation method, device and system, the method includes: obtaining a current measurement value of a current battery; acquiring a current voltage measurement value of the battery; calculating a model-based open circuit voltage based on the current measurement, the voltage measurement, and a battery model, wherein the battery model includes a battery resistance component and a battery voltage component for characterizing a relationship between the current measurement, the voltage measurement, and the model-based open circuit voltage; calculating a current voltage-based state of charge; receiving a previous state of charge; calculating a current state of charge based on coulomb counting; and calculating a current state of charge.

Description

Battery parameter calculation method, device and system

Technical Field

The present application relates to the field of battery management technologies, and in particular, to a battery parameter calculation method, and a battery parameter calculation device and system.

Background

Lithium batteries are a non-linear chemical energy storage system that varies over time. State of charge (SOC) is a key parameter to track the percentage of the current remaining capacity to the maximum capacity of the battery. SOC actually reflects the real-time internal chemical state of the battery, but can only be estimated from limited measurable battery parameters, including voltage, current, and temperature of the battery. Because of the complex non-linear relationship of SOC with temperature, current, and inherent characteristics of the battery, such as Open Circuit Voltage (OCV) and resistance, accurate estimation of SOC over the life of the battery over different temperatures and load usage scenarios is challenging.

Typically, one simple method of estimating SOC is to use a coulomb counter to accumulate the capacity passed during charging or discharging. However, the accuracy of SOC is limited by the initial SOC value and the current integration accumulated error. Although SOC may be modified to some extent when the battery is fully charged or discharged, this approach is not suitable for batteries operating within a narrower SOC range because it rarely reaches a fully charged or discharged condition, thereby modifying the initial SOC of the coulomb counter.

Another method of estimating SOC is to combine OCV correction and coulomb counter, but not apply a battery model. In this method, OCV correction is used to adjust the initial SOC at battery relaxation, the measured voltage is directly used as the OCV value, and the SOC is corrected according to the OCV value. However, this approach is still limited if the battery is continuously charged or discharged and a relaxed condition cannot be reached for a long time to trigger OCV correction.

The methods for estimating SOC described above have certain limitations. A simple and efficient method is desired to accurately estimate the SOC of the battery. The present application addresses this need.

Disclosure of Invention

By providing a method of accurately calculating a state of charge (SOC) of a battery based on a battery model, preferred embodiments of the present disclosure generally solve or circumvent these and other problems, and technical advantages are generally achieved.

The application provides a method for calculating a state of charge, SOC, of a battery, comprising: acquiring a current measured value of the battery; acquiring a current voltage measurement value of the battery; calculating a model-based open circuit voltage, OCV, of the battery based on the current measurement, the voltage measurement, and a battery model _model Wherein the battery model includes a battery resistance component and a battery voltage component for characterizing the current measurement, the voltage measurement, and the OCV of the battery _model A relationship between; based on the OCV _model Calculating a current voltage-based state of charge VSOC _k+1 The method comprises the steps of carrying out a first treatment on the surface of the Receiving a previous state of charge SOC _k The method comprises the steps of carrying out a first treatment on the surface of the Based on the SOC _k Calculating current coulomb count-based chargeState CCSOC _k+1 The method comprises the steps of carrying out a first treatment on the surface of the Based on the VSOC _k+1 And the CCSOC _k+1 Calculating the current state of charge SOC _k+1 。

Optionally, the method further comprises: receiving the previous open circuit voltage OCV _k The method comprises the steps of carrying out a first treatment on the surface of the Based on the OCV _model And the OCV _k Calculating the current open circuit voltage OCV _k+1 And based on the OCV _k+1 Calculating the VSOC _k+1 。

Optionally, the battery resistance component includes an equivalent series resistance component and a resistance component in an RC network, and the calculating the OCV of the battery _model Comprises calculating an OCV of the battery based on the current measurement, the voltage measurement, the equivalent series resistance component value, and a resistance component value in an RC network _model 。

Optionally, the battery resistance component includes an equivalent series resistance component and a transient resistance component, and the calculating the OCV of the battery _model Comprises calculating an OCV of the battery based on the current measurement, the voltage measurement, the equivalent series resistance component value, and the transient resistance component value _model 。

Optionally, the calculating the current state of charge SOC _k+1 Including at the VSOC according to an allocation _k+1 And the CCSOC _k+1 Weight on to calculate the SOC _k+1 The weight depends on the SOC confidence and the current measurement of the battery.

Optionally, the calculating the current state of charge SOC _k+1 Includes obtaining the VSOC _k+1 And the CCSOC is connected with _k+1 Is a difference in (2); based on the SOC error gain generated by the difference and the CCSOC _k+1 Calculating the SOC _k+1 The SOC error gain is dependent on SOC confidence and a current measurement of the battery.

Optionally, the method further comprises: the above steps are repeated to base on the next voltage-based state of charge VSOC _k+2 And the next coulomb count-based state of charge CCSOC _k+2 To calculate the next state of charge SOC _k+2 。

Optionally, the method further comprises: acquiring a current temperature measurement of the battery and calculating the OCV of the battery based on the temperature measurement _model The battery model also characterizes the temperature measurements and the OCV _model Relationship between them.

The present application also provides an apparatus for calculating a state of charge, SOC, of a battery, the apparatus comprising: an open circuit voltage OCV calculation circuit configured to receive a current measurement of the battery and a current measurement of a voltage of the battery, and calculate a model-based open circuit voltage OCV of the battery based on the current measurement, the voltage measurement, and a battery model _model Wherein the battery model includes a battery resistance component and a battery voltage component for characterizing the current measurement, the voltage measurement, and the OCV of the battery _model A relationship between; an SOC calculation circuit configured to be based on the OCV _model Calculating a current voltage-based state of charge VSOC _k+1 And is configured to receive a previous state of charge, SOC _k And based on the SOC _k Calculating current state of charge CCSOC based on coulomb count _k+1 The method comprises the steps of carrying out a first treatment on the surface of the And an SOC adaptation circuit configured to be based on the VSOC _k+1 And the CCSOC _k+1 Calculating the current state of charge SOC _k+1 。

Optionally, the apparatus further comprises: an OCV filter circuit configured to be based on the OCV _model And the previous open circuit voltage OCV _k Calculating the current open circuit voltage OCV _k+1 Wherein the SOC calculation circuit is further configured to be based on the OCV _k+1 Calculating the VSOC _k+1 。

Optionally, the battery resistance component includes an equivalent series resistance component and a resistance component in an RC network, the open circuit voltage calculation circuit is further configured to calculate the OCV of the battery based on the current measurement, the voltage measurement, the equivalent series resistance component value, and a resistance component value in an RC network _model 。

Alternatively, the process may be carried out in a single-stage,the battery resistance component includes an equivalent series resistance component and a transient resistance component, and the open circuit voltage calculation circuit is further configured to calculate the OCV of the battery based on the current measurement, the voltage measurement, the equivalent series resistance component value, and the transient resistance component value _model 。

Optionally, the SOC adaptation circuitry is further configured to, according to an allocation at the VSOC _k+1 And the CCSOC _k+1 Weight on to calculate the SOC _k+1 The weight depends on the SOC confidence and the current measurement of the battery.

Optionally, the SOC adaptation circuit is further configured to obtain the VSOC _k+1 And the CCSOC is connected with _k+1 Is a difference in (2); based on the SOC error gain generated by the difference and the CCSOC _k+1 Calculating the SOC _k+1 The SOC error gain is dependent on SOC confidence and a current measurement of the battery.

Optionally, the OCV calculation circuit is further configured to receive a current temperature measurement of the battery and calculate the OCV of the battery based on the temperature measurement _model Wherein the battery model is further used to characterize the temperature measurement and the OCV of the battery _model Relationship between them.

The present application also provides a system for calculating a state of charge SOC of a battery, characterized in that the system comprises: a current sensor configured to measure a current value of the current battery; a voltage sensor configured to measure a current voltage value of the battery; and an SOC computing device including: a battery model device configured to receive a current value of the battery and a voltage value of the battery to generate a model-based Open Circuit Voltage (OCV) of the battery _model The method comprises the steps of carrying out a first treatment on the surface of the And a control circuit configured to be based on the OCV _model Calculating a current voltage-based state of charge VSOC _k+1 Receive the previous state of charge SOC _k And based on the SOC _k Calculating current state of charge CCSOC based on coulomb count _k+1 And based on the VSOC _k+1 And said CCSOC _k+1 Calculating the current state of charge SOC _k+1 。

Optionally, the control circuit is further configured to receive a previous open circuit voltage OCV _k The method comprises the steps of carrying out a first treatment on the surface of the Based on the OCV _model And the OCV _k Calculating the current open circuit voltage OCV _k+1 And based on the OCV _k+1 Calculating the VSOC _k+1 。

Optionally, the battery model includes an equivalent series resistance component and a transient resistance component, the battery model device is further configured to calculate the OCV of the battery based on the current value, the voltage value, the equivalent series resistance component value, and a transient resistance component value _model 。

Optionally, the control circuit is further configured to control the operation of the VSOC based on the allocation _k+1 And the CCSOC _k+1 Weight on to calculate the SOC _k+1 The weight depends on the SOC confidence and the current measurement of the battery.

Optionally, the control circuit is further configured to obtain the VSOC _k+1 And the CCSOC is connected with _k+1 Is a difference in (2); based on the SOC error gain generated by the difference and the CCSOC _k+1 Calculating the SOC _k+1 The SOC error gain is dependent on SOC confidence and a current measurement of the battery.

The application can realize at least one of the following beneficial effects: the method provided by the application can directly calculate the SOC based on the voltage according to the model, and then correct the SOC based on the coulomb count as feedback, so that the determination of the correction weight of the voltage to the SOC based on the current integration under different scenes becomes simple and visual, namely, the SOC based on the coulomb count is directly corrected by using the SOC based on the voltage, and the method is easy to realize in a chip or equipment of a battery management system.

The foregoing has outlined rather broadly the features and technical advantages of the present application in order that the detailed description of the application that follows may be better understood. Additional features and advantages of the application will be described hereinafter which form the subject of the claims of the application. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present application. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the application as set forth in the appended claims.

Drawings

For a more complete understanding of the present application, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 depicts a high-level block diagram of an apparatus for calculating state of charge (SOC) of a battery, according to one embodiment of the present application;

fig. 2 shows an equivalent circuit model diagram of a battery provided by an embodiment of the present application;

fig. 3 is a diagram showing an equivalent circuit model of a battery according to another embodiment of the present application;

FIG. 4 depicts a high-level block diagram of a battery model provided by an embodiment of the present application;

FIG. 5 depicts a high-level block diagram of an apparatus for calculating state of charge (SOC) of a battery, according to another embodiment of the present application;

FIG. 6 depicts a high-level block diagram of an OCV filter provided in accordance with one embodiment of the present application;

FIG. 7 depicts a high-level block diagram of an SOC adapter provided by one embodiment of the application;

FIG. 8 depicts a high-level block diagram of a SOC adapter provided by another embodiment of the application;

FIG. 9 is a flow chart of a method for calculating the state of charge of a battery according to an embodiment of the present application;

FIG. 10 shows a graph of time parameters of resistance and RC networks versus SOC and temperature in a battery model, according to one embodiment of the present application;

FIG. 11 is a graph showing open circuit voltage versus state of charge and temperature for a battery according to an embodiment of the present application;

FIG. 12 is a flowchart of a method for creating a battery model according to one embodiment of the present application;

FIG. 13 depicts a high-level block diagram of a system for calculating state of charge (SOC) of a battery, according to one embodiment of the present application; and

fig. 14 depicts a high-level block diagram of a system for calculating state of charge (SOC) of a battery, in accordance with another embodiment of the present application.

Corresponding numerals and symbols in the various drawings generally indicate corresponding parts unless otherwise indicated. The drawings are not necessarily to scale in order to clearly illustrate the relevant aspects of the various embodiments.

Detailed Description

The following description of the embodiments of the present application will be made more apparent and fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the application are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

In general, a better method of improving the accuracy of SOC estimation is to introduce a battery model to estimate SOC. In this method, the measured battery voltage may be used continuously to correct the SOC calculated by the current-based coulomb counter, whether the battery is operating in charge, discharge or relaxation mode. For example, a model-based battery voltage is calculated and compared to the measured battery voltage, which is then used as a feedback factor to correct the coulomb count-based SOC to produce a new battery SOC. However, this method has the disadvantage that the measured voltage is used as feedback to correct the SOC in an implicit manner, and that the appropriate correction weights cannot be determined from their physical meaning, but rather that the SOC performance is ensured in a trial-and-error manner at different temperatures and loads. Thus, if the voltage-based SOC can be calculated directly from the model and then used as a correction feedback for the coulomb count-based SOC, the determination of the correction weights in different scenarios is simplified (i.e., the coulomb count-based SOC is corrected directly with the voltage-based SOC, rather than with the measured voltage), and is easy to implement in a Battery Management System (BMS) chip or device.

In one embodiment of the application, a system for calculating SOC may include current, temperature and voltage sensors to obtain corresponding data. The system may implement a battery model based algorithm. The cell model may consist of an ohmic resistor in series and RC elements in order of 1 to n. The battery model may generate model-based OCV values by compensating the measured voltage with a voltage drop caused by the battery resistance. The OCV value may be converted into an SOC value, that is, a voltage-based SOC, and the current SOC value may be generated by correcting the coulomb count-based SOC value with this SOC as feedback. The correction weight of the voltage-based SOC can be adjusted by the SOC adapter to ensure the accuracy and robustness of the SOC calculation.

Referring to fig. 1, fig. 1 is a high-level block diagram of an apparatus for calculating a state of charge (SOC) of a battery according to an embodiment of the present application.

As shown in fig. 1, the apparatus 10 for calculating SOC of a battery may acquire data reflecting the state of the battery measured by various sensors. For example, the device 10 may obtain a present current value I of the battery measured by the current sensor _k+1 . In one embodiment, the current sensor may use a sense resistor to detect current flowing into and out of the battery. The device 10 can obtain the current voltage value U of the battery measured by the voltage sensor _k+1 . In an embodiment, the battery is used to power the electronic device, and the measured present current and voltage values reflect information of the load the electronic device loads on the battery. The device 10 may also obtain the current temperature value T of the battery measured by the temperature sensor _k+1 . The temperature measuring element of the temperature sensor may be positioned around the battery.

The apparatus 10 for calculating the SOC of the battery further includes a coulomb counter 106. The coulomb counter 106 receives the present current value I measured from the current sensor _k+1 And generates a current state of charge delta SOC _k+1 . The summing element 108 adds the current state of charge increment ΔSOC _k+1 And the previous state of charge SOC _K To generate a state of charge CCSOC based on the rendition count _k+1 。

The apparatus 10 further includes a voltage-based SOC calculator 104. Generated by the battery model 102Model-based open circuit voltage OCV _model Is fed into a voltage-based SOC calculator 104 to generate a current voltage-based SOC value VSOC _k+1 。VSOC _k+1 Is used to communicate with CCSOC _k+1 Comparing and combining to generate a current state of charge SOC _k+1 . For example, comparing VSOC using SOC adapter 110 _k+1 And CCSOC (Central control System) _k+1 。

In the present application, the SOC adapter 110 may also be referred to as an SOC adapter circuit. The coulomb counter 106, voltage-based SOC calculator 104, and summing element 108 may also be referred to as an SOC calculation circuit to generate VSOC _k+1 And CCSOC (Central control System) _k+1 . The battery model 102 may also be referred to as an Open Circuit Voltage (OCV) calculation circuit or battery model device. The SOC adaptation circuit and the SOC calculation circuit may also be referred to as a control circuit.

The apparatus 10 also includes an SOC delay circuit 112 that receives the output of the SOC adapter 110 to generate the previous state of charge SOC _k And SOC is taken _k Feed into the summing element 108 and the battery model 102.

The battery model 102 may be used to estimate the open circuit voltage of the battery, which outputs a model-based open circuit voltage OCV _model . The battery model 102 is based on the acquired current measurements, voltage measurements, temperature measurements, and the received previous state of charge, SOC, of the battery _k To output OCV _model 。

Fig. 2 shows an equivalent circuit model diagram on which the battery model is based. The equivalent circuit model includes a voltage source that represents the open circuit voltage OCV of the battery. The equivalent circuit model also comprises an equivalent series resistance R _ohmic Which reflects the transient resistance characteristics of the battery. The equivalent circuit model also includes n RC parallel networks reflecting the charge transfer reactions and charge diffusion characteristics of the battery. The number n of RC networks may be 1 to 3 or even more. More RC networks mean more complex computational effort and more resources consumed by the device to run the battery model. The components (OCV, R) of the battery model in FIG. 2 _ohmic RC network) depends on various parameters, such as temperature, SOC, load, degree of aging, etc., and the relationship between these parameters is nonlinear,the relationship between OCV and SOC is nonlinear and temperature dependent; the relationship between the individual resistance values and the SOC in the model is also nonlinear and temperature dependent. The relationship between the different parameters can be expressed in terms of a system of mathematical equations. Taking a second order equivalent model (n=2) as an example, the discrete form of the battery model can be described as the following formula:

OCV(t _k+1 )＝U(t _k+1 )-I(t _k+1 )*R _ohmic (SOC(t _k ),T(t _k+1 ))-I _R1 (t _k+1 )*R1(SOC(t _k ),T(t _k+1 ))-I _R2 (t _k+1 )*R2(SOC(t _k ),T(t _k+1 )) (3)

wherein I is _R1 Representing the current flowing through resistor R1; i _R2 Representing the current flowing through resistor R2; i represents the flow-through resistance R _ohmic Is set to be a current of (a); u represents the battery terminal voltage measured in real time; OCV represents the open circuit voltage of the battery; t represents the battery temperature; SOC represents state of charge. t is t _k Representing the previous time in the cycle; t is t _k+1 Indicating the current time in the cycle.

The open circuit voltage OCV of the battery can be calculated as the battery voltage U minus the equivalent series resistance R _ohmic Voltage drop across n RC networks.

In some embodiments, it may be desirable to run a complex battery model with limited resources, and then the battery model may be reduced to the equivalent circuit model shown in fig. 3. Referring to FIG. 3, n RC networks are approximated as a constant resistance R _slow It only considers short RC responses in seconds or even minutes, and ignores long RC responses. In addition, R _slow Can be based on the temperature range DeltaT and the load range DeltaTR _L The SOC range Δsoc and the time period Δt. For example, the compensation coefficient may be determined as a simple function f (ΔT, ΔSOC).

Fig. 4 depicts a high-level block diagram of a battery model provided in accordance with an embodiment of the present application. As shown in fig. 4, the battery model 102 includes R _ohmic Module 204 and RC _1…n A module 202. The input parameters of the battery model 102 include the current battery voltage measurement U _k+1 Current measurement I of the current battery _k+1 Current battery temperature value T _k+1 And the previous state of charge SOC of the battery _k . These input parameters are processed by the battery model 102 to generate the current open circuit voltage OCV of the battery _model I.e. model based open circuit voltage.

R _ohmic Module 204 generates R for the battery _ohmic Value of R _ohmic The value is fed into a product element 216 to output a representation R _ohmic And I _k+1 Voltage V of the product _ESR 。RC _1…n The module 202 can generate a plurality of resistance values R ₁ …R _n And a current value I corresponding to the plurality of resistance values _R1 …I _Rn . These resistance values and current values are fed into the product element 212 to output a representation R ₁ …R _n And I _R1 …I _Rn Multiple voltage values V of the product _R1 …V _Rn Subsequently V _R1 …V _Rn Outputs the sum of the voltage values Σv via the summing element 214 _Rn . For example, for a second order battery model, Σv _R2 ＝I _R1 *R ₁ +I _R2 *R ₂ . The differencing element 218 incorporates U _k+1 And V _ESR To generate U _k+1 And V is equal to _ESR The difference element 220 combines the difference and Σv _Rn To generate a representation U _k+1 And V is equal to _ESR Sum sigma V _Rn And model-based open circuit voltage OCV _model 。

Fig. 5 depicts a high-level block diagram of an apparatus for calculating state of charge (SOC) of a battery, in accordance with another embodiment of the present application. The high-level block diagram shown in fig. 5 is similar to that shown in fig. 1, except that the device 10 also includes an OCV filter 114, which may also be referred to as an OCV filter circuit.

An OCV filter 114 is connected between the battery model 102 and the voltage-based SOC calculator 104. OCV filter 114 receives the OCV output from battery model 102 _model And outputs the current open circuit voltage OCV to the SOC calculator 104 _k+1 . In this embodiment, the SOC calculator 104 is based on the OCV _k+1 Calculating a current voltage-based state of charge VSOC _k+1 . The OCV filter 114 can avoid significant OCV caused by abrupt current changes or battery model errors _model The voltage value jumps to ensure the open circuit voltage OCV input to the SOC calculator 104 _k+1 Thereby improving the accuracy of the whole device SOC estimation.

Fig. 6 depicts a high-level block diagram of an OCV filter provided by one embodiment of the present application. The OCV filter 114 includes a weight module 402 that receives a current model-based open circuit voltage OCV _model Open circuit voltage OCV of previous time _k And generates the current open circuit voltage OCV through a preset weight factor a _k+1 I.e. OCV _k+1 ＝aOCV _model +(1-a)OCV _k . The weight factor a depends on the battery model accuracy and the current load size, for example, when the battery model accuracy is good or the current is small, the open circuit voltage value OCV is calculated based on the model _model The accuracy is high, the true electrode potential state in the battery can be accurately reflected, and the value of a can be larger to improve the OCV _model For OCV _k+1 To calculate a more accurate VSOC _k+1 Otherwise, the value a should be selected to be smaller.

The OCV filter 114 also includes a delay circuit 404 that receives the previous open circuit voltage OCV _k And feeds it back to the weight module 402. The delay circuit 404 is used to preserve the previous (or current) open circuit voltage and is used to calculate the current (or next) open circuit voltage.

Referring back to fig. 1 or 5, soc adapter 110 receives the current coulomb count-based state of charge, the current voltage-based state of charge, the confidence of the voltage-based state of charge, and the current measurement to generate the current state of chargeStatus of the device. FIG. 7 depicts a high-level block diagram of an SOC adapter, according to one embodiment of the application. As shown in fig. 7, SOC adapter 110 includes VSOC weighting means 701 for generating a weight factor assigned between the voltage-based state of charge and the coulomb count-based state of charge based on the received VSOC confidence and the current measurement of the present battery, thereby calculating the present state of charge. Specifically, the VSOC weighting device 701 outputs a weighting factor w to the product element 703 and the differencing element 705. The product element 703 receives the current voltage-based state of charge VSOC _k+1 And a weight factor w to output the product of both to the summing element 709. The difference element 705 outputs the difference between 1 and the weight factor w. The product element 707 receives the current coulomb count based state of charge CCSOC _k+1 And the difference value output by the difference element 705 to output the product of both to the summing element 709. Finally, summing element 709 combines the outputs of product element 703 and product element 707 to generate a current state of charge, SOC _k+1 . In one embodiment, the weight factor w has a value between 0 and 1. . The VSOC confidence level represents the confidence level of the VSOC value, which can be expressed by the OCV _model 、OCV _k Current I _k+1 An equivalent amount is determined, for example, that there is a sudden change in current in the current period, from 0.1C at time t=k to 1C (C is the multiplying factor) at time t=k+1, and the open circuit voltage OCV calculated at this time is calculated _model 3800mV, and OCV at time t=k last time _k =3900 mV, this model-based calculation of OCV since the electromotive force inside the battery is normally unlikely to cause transient large-scale jumps _model Filtered OCV _k+1 With a large deviation from true values, VSOC _k+1 The reliability is small, and w should take a small value, i.e. not substantially to CCSOC based on current integration _k+1 And (5) making correction.

FIG. 8 depicts a high-level block diagram of an SOC adapter according to another embodiment of the present application. In this embodiment, an error gain value of the SOC is generated and fed back to the state of charge based on the coulomb count, thereby calculating the current state of charge. Specifically, as shown in FIG. 8, the differencing element 803 generates the current voltage-based state of charge VSOC _k+1 And the current baseState of charge CCSOC in coulomb counting _k+1 Is a difference in (c). The SOC error gain device generates an error gain coefficient based on the received VSOC confidence level and the current measurement value of the current battery, and based on the VSOC _k+1 And CCSOC (Central control System) _k+1 The difference of (c) outputs the SOC error gain value to the summing element 805. Summing element 805 incorporates CCSOC _k+1 And the SOC error gain value to generate the current state of charge SOC _k+1 . The error gain method in this embodiment can more intuitively obtain the VSOC calculated from the model based on the voltage than the embodiment shown in fig. 7, which determines the final correction weight w more depending on the confidence _k+1 Integrated with coulomb CCSOC _k+1 The difference between them, thereby facilitating determination of the final pair CCSOC _k+1 The difference should not vary much over a sampling period, if so, indicating VSOC _k+1 If the calculation error is larger, the output of the error gain module should be very small or directly 0, so as to ensure that the SOC is calculated by using coulomb integration as the main component.

Fig. 9 shows a flowchart of a method for calculating a state of charge of a battery according to an embodiment of the present application. The flow chart shown in fig. 9 is merely an example, which should not unduly limit the scope of the claims. Those of ordinary skill in the art will recognize many variations, alternatives, and modifications. For example, various steps shown in fig. 9 may be added, removed, replaced, rearranged, and repeated.

In step 902, the apparatus 10 that calculates the SOC of the battery may acquire various battery measurements. For example, the apparatus 10 obtains a current value I through the battery measured by a current sensor _k+1 The method comprises the steps of carrying out a first treatment on the surface of the The apparatus 10 acquires a battery voltage value U measured by a voltage sensor _k+1 The method comprises the steps of carrying out a first treatment on the surface of the Temperature T of battery _k+1 Can be measured and acquired by a temperature sensor.

In step 904, the battery model 102 receives the various battery measurements obtained in step 902, as well as the previous state of charge, SOC _k To update or generate model-based open circuit voltage OCV _model 。

In step 906, the device 10 is based on the previous state of charge SOC _k Determination in a battery modelIs described. Referring back to fig. 2 and 3, the resistance R in the equivalent circuit diagram of the battery model _ohmic 、R ₁ …R _n 、R _slow And the time parameter Tau of the RC network depends on variables such as SoC, temperature and battery state of the battery (e.g., the battery is in a charged state or a discharged state; the battery is being charged in a constant current mode or in a constant voltage mode, etc.). The relationship of the resistance or time parameter and these variables can be represented by a table or graph. The data for the table or graph may be stored in memory for recall by the processor. Fig. 10 shows a graph of time parameters of resistance and RC network versus SOC and temperature in a battery model provided in accordance with an embodiment of the present application. In this embodiment, the battery model is a first-order equivalent circuit model of the battery. As shown in the upper diagram in fig. 10, the abscissa represents the state of charge SOC, and the ordinate represents the resistance R _ohmic The solid line in the figure shows the resistance R at 25 degrees Celsius _ohmic Graph of curve versus SOC. The dotted line indicates the resistance R at 0 degrees Celsius _ohmic Graph of curve versus SOC. The relationship between battery resistance and SOC can be obtained by Hybrid Pulse Power Characteristic (HPPC) detection. Similarly, in the middle graph in FIG. 10, the resistance R is shown at 0 degrees Celsius and 25 degrees Celsius ₁ Graph of curve versus SOC. In the lower graph in fig. 10, a graph of time parameter Tau1 of the RC network versus SOC in the first-order equivalent circuit at 0 degrees celsius and 25 degrees celsius is shown. As shown in fig. 10, the resistor R _ohmic And resistance R ₁ Shows a non-linear negative correlation with the SOC, while the time parameter Tau1 shows a non-linear positive correlation with the SOC.

In step 908, the apparatus 10 determines a model-based open circuit voltage, OCV, of the battery _model . Based on the resistance value determined in step 906 and the current and voltage values received in step 904, the apparatus 10 may calculate the OCV from the equivalent circuits in fig. 2 and 3 _model . For example, taking a first-order equivalent model as an example, OCV _model ＝U _k+1 -I _k+1 *R _ohmic -I _R1 *R ₁ 。

In step 910, the apparatus 10 sets an OCV _model Filtering to generate OCV _K+1 . In other embodiments, step 910 may also be omitted, where the OCV _model Directly feed into SOC calculator 104 in fig. 1.

In step 912, the device 10 is based on the received OCV _K+1 Calculation of VSOC _k+1 . The OCV of a battery depends on a number of factors, such as the SoC, temperature, and battery state of the battery (e.g., the battery is in a charged state or a discharged state; the battery is being charged in a constant current mode or in a constant voltage mode, etc.). For simplicity, the OCV may be expressed as a function of SOC. Fig. 11 shows a graph of open circuit voltage versus state of charge and temperature for a battery according to an embodiment of the present application. The long-dashed, short-dashed and solid lines in fig. 11 represent graphs of open circuit voltage versus state of charge of the battery at 0 degrees celsius, 25 degrees celsius and 55 degrees celsius, respectively. These graphs can be obtained by capacity and OCV testing. In some embodiments, the VSOC value may be calculated by interpolating a lookup table. In other embodiments, to reduce the data stored in memory, the SOC-OCV relationship may be fitted to a mathematical function, such as a polynomial equation of a plurality of times. If desired, the curve may be divided into segments and then fit separately to a simpler equation.

In step 914, the SOC based on the coulomb count is determined. The device 10 generates an delta state of charge, ΔSOC, from the current measurement, by comparing the delta state of charge, SOC, with the current state of charge, SOC _k+1 Summing to produce a current coulomb count-based state of charge CCSOC _k+1 。

In step 916, the apparatus 10 is based on VSOC _k+1 And CCSOC (Central control System) _k+1 Calculating the current state of charge SOC _k+1 Such as using SOC adapter 110 shown in fig. 1. Specifically, in one embodiment, a weight factor assigned between the voltage-based state of charge and the coulomb count-based state of charge is generated based on the received VSOC confidence and the current measurement of the present battery, thereby calculating the present state of charge. In another embodiment, an error gain value for the SOC is generated and added to the state of charge based on the coulomb count to calculate the current state of charge.

After the calculation of the current SOC is completed, the entire process loops back to step 902 and repeats the calculation of the next SOC of the battery in a subsequent iteration, where the current battery SOC is used as the previous battery SOC.

Fig. 12 shows a flowchart of a method for creating a battery model according to an embodiment of the present application.

In step 1202, a characterization test is performed on the characteristics of the battery to obtain a relationship map, formula, or list of battery parameters. For example, the SOC-OCV-T curve of the battery shown in FIG. 11, and the R-SOC-T curve of the battery shown in FIG. 10 were obtained by characterization tests.

In step 1204, for the parameters in the relationship diagram of step 1202, the parameters of impedance and time parameters are identified by HPPC test data and according to the relationships of current, voltage, and time parameters in equations 1 and 2 above, to build an equivalent circuit model. As shown in FIG. 2, the equivalent circuit pattern may be an n-order circuit model (n.gtoreq.1).

Fig. 13 depicts a high-level block diagram of a system for calculating state of charge (SOC) of a battery in accordance with an embodiment of the present application. The system includes a temperature sensor 1002, a voltage sensor 1004, a current sensor 1006, and an apparatus 1300 that calculates a battery SOC. In this embodiment, device 1300 may include memories such as Flash memory 1302 and SRAM 1304. Flash memory 1302 may be used to store specific coefficients or settings for the battery, as well as other battery parameters generated from battery characteristics. For example, flash memory 1302 may store a graph or table of relationships for SOC-OCV-T of the battery shown in FIG. 11. Flash memory 1302 may also store a function that fits the curve of SOC-OCV-T shown in FIG. 11. Flash memory 1302 may also store various mathematical equations, such as mathematical equation parameters that characterize the equivalent circuit diagram shown in FIG. 2. Flash memory 1302 may also store state quantities (e.g., SOC values) and other parameters (e.g., time, OCV times, etc.) of the algorithm calculation output.

The device 1300 may include I ² C module 1306.I ² The C-module 1306 may provide communication with the device 1300, e.g., configuring the device, reading and writing data, etc.

The device 1300 may also include an ADC module for converting various analog measurement voltages into suitable digital signals. The ADC module includes a voltage ADC 1308 for converting voltage measurements and temperature measurements of the battery. The ADC module also includes a current ADC 1310 for converting current measurements of the battery. In some embodiments, the current ADC 1310 and the voltage ADC 1308 may operate synchronously to provide conversion at the same time.

The apparatus 1300 includes a processing module CPU 1312. The CPU 1312 may include a BMS algorithm module and a driver. The BMS algorithm module may be used to perform the above-described method flows. For example, the method flow in fig. 9 and 10.

The various elements or modules in the device 1300 described above may be interconnected by a communication and control bus 1314 to permit transmission of data.

In some embodiments, a more complex Battery Management System (BMS) may be required for a battery system having many battery cells and a complex electrical structure, such as a battery pack of an electric car or an energy storage system. Fig. 14 depicts a high-level block diagram of a system for calculating state of charge (SOC) of a battery, in accordance with another embodiment of the present application. The system includes a plurality of sensors and a device that calculates a battery SOC. The apparatus for calculating the battery SOC includes two Analog Front End (AFE) chips and one microcontroller unit (MCU) chip. In other embodiments, the Analog Front End (AFE) chip can be expanded into multiple chips according to actual requirements. Each AFE chip corresponds to a plurality of sensors. Specifically, the AFE chip 1 can acquire a temperature measurement value by the temperature sensor 1402a, a voltage measurement value by the voltage sensor 1404a, and a current measurement value by the current sensor 1406. The AFE chip 2 can acquire a temperature measurement value by the temperature sensor 1402b and a voltage measurement value by the voltage sensor 1404 b.

AFE chip 1 includes a voltage ADC 1408a for converting the analog signal input of the sensor into temperature and voltage values in digital form. AFE chip 1 also includes current ADC 1408a for converting the analog input of the sensor to a current value in digital form.

The AFE chip 1 may include a watchdog module 1412a for monitoring whether the AFE chip 1 works as intended. AFE chip 1 may include LDO module 1418a for providing voltage input to internal circuitry. The AFE chip 1 may include an equalization module 1414a for controlling or driving equalization circuitry to reduce inconsistencies in the charge and discharge of the individual cells in the battery pack, thereby improving battery pack life. The AFE chip 1 may include a Serial Peripheral Interface (SPI) module that provides a communication channel with other AFE chips or MCU chips. The various elements or modules in AFE chip 1 may be interconnected by a communication and control bus 1420a to allow for the transfer of data. Other modules may be added to meet specific requirements of the chip according to different requirements. As shown in fig. 14, the AFE chip 2 also includes similar modules in the above AFE chip 1 to achieve the same functions, which are not described herein again.

The MCU chip may be a general purpose commercially available chip supporting fixed point or floating point data processing. The MCU chip includes volatile memory, such as RAM 1422, and nonvolatile memory, such as ROM 1424. These memories may be used to store specific coefficients or settings of the battery, as well as other battery parameters generated from battery characteristics, such as storing a graph or table of relationships of the SOC-T-OCV of the battery shown in fig. 11. These memories may also store functions that fit the curve of the SOC-T-OCV shown in FIG. 11, or store various mathematical equations or formulas, such as those that characterize the equivalent circuit diagram shown in FIG. 2.

The MCU chip also includes a processing module CPU 1426. The CPU 1426 may include a BMS algorithm module and a driver. The BMS algorithm module may be used to perform the above-described method flows. For example, the method flow in fig. 9 and 10. The MCU chip may include an LDO module 1418c for providing voltage inputs to internal circuitry. The MCU chip may also include a Serial Peripheral Interface (SPI) module that provides a communication channel with other AFE chips. In other embodiments, a Controller Area Network (CAN) may be selected as the communication medium between the chips or components in the device that calculates the battery SOC instead of SPI.

Although embodiments of the present application and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Furthermore, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. It will be readily apparent to those of ordinary skill in the art from this disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present application. It is therefore intended that the following appended claims include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

1. A method for calculating a state of charge (SOC) of a battery, comprising:

acquiring a current measured value of the battery;

acquiring a current voltage measurement value of the battery;

calculating a model-based Open Circuit Voltage (OCV) of the battery based on the current measurement, the voltage measurement, and a battery model _model ) Wherein the battery model includes a battery resistance component and a battery voltage component for characterizing the current measurement, the voltage measurement, and the OCV of the battery _model A relationship between;

based on the OCV _model Calculating a current voltage-based state of charge (VSOC _k+1 )；

Receives the previous state of charge (SOC _k )；

Based on the SOC _k Calculating a current state of charge based on coulomb counting (CCSOC _k+1 ) The method comprises the steps of carrying out a first treatment on the surface of the And

based on the VSOC _k+1 And the CCSOC _k+1 Calculating the current state of charge (SOC _k+1 )。

2. The method of claim 1, further comprising:

receiving a previous Open Circuit Voltage (OCV) _k ) The method comprises the steps of carrying out a first treatment on the surface of the And

based on the OCV _model And the OCV _k Calculating the current Open Circuit Voltage (OCV) _k+1 ) And based on the OCV _k+1 Calculating the VSOC _k+1 。

3. The method of claim 1, wherein,

the battery resistance component includes an equivalent series resistance component and a resistance component in an RC network, and the calculating the OCV of the battery _model Comprises calculating an OCV of the battery based on the current measurement, the voltage measurement, the equivalent series resistance component value, and a resistance component value in an RC network _model 。

4. The method of claim 1, wherein,

the battery resistance component includes an equivalent series resistance component and a transient resistance component, and the calculating the OCV of the battery _model Comprises calculating an OCV of the battery based on the current measurement, the voltage measurement, the equivalent series resistance component value, and the transient resistance component value _model 。

5. The method of claim 1, wherein,

the calculation of the current state of charge (SOC _k+1 ) Including at the VSOC according to an allocation _k+1 And the CCSOC _k+1 Weight on to calculate the SOC _k+1 The weight depends on the SOC confidence and the current measurement of the battery.

6. The method of claim 1, wherein,

the calculation of the current state of charge (SOC _k+1 ) Includes obtaining the VSOC _k+1 And the CCSOC is connected with _k+1 Is a difference in (2); based on the SOC error gain generated by the difference and the CCSOC _k+1 Calculating the SOC _k+1 The SOC error gain is dependent on SOC confidence and a current measurement of the battery.

7. The method of claim 1, further comprising:

the above steps are repeated to determine the next voltage-based state of charge (VSOC _k+2 ) And next coulomb count-based state of charge (CCSOC) _k+2 ) To calculate the next state of charge (SOC) _k+2 )。

8. The method of claim 1, further comprising:

acquiring a current temperature measurement of the battery and calculating the OCV of the battery based on the temperature measurement _model The battery model also characterizes the temperature measurements and the OCV _model Relationship between them.

9. An apparatus for calculating a state of charge (SOC) of a battery, the apparatus comprising:

an Open Circuit Voltage (OCV) calculation circuit configured to receive a current measurement of the battery and a current voltage measurement of the battery, and calculate a model-based Open Circuit Voltage (OCV) of the battery based on the current measurement, the voltage measurement, and a battery model _model ) Wherein the battery model includes a battery resistance component and a battery voltage component for characterizing the current measurement, the voltage measurement, and the OCV of the battery _model A relationship between;

an SOC calculation circuit configured to be based on the OCV _model Calculating a current voltage-based state of charge (VSOC _k+1 ) And is configured to receive a previous state of charge (SOC _k ) And based on the SOC _k Calculating a current state of charge based on coulomb counting (CCSOC _k+1 ) The method comprises the steps of carrying out a first treatment on the surface of the And

an SOC adaptation circuit configured to be based on the VSOC _k+1 And the CCSOC _k+1 Calculating the current state of charge (SOC _k+1 )。

10. The apparatus of claim 9, wherein the apparatus further comprises:

an OCV filter circuit configured to be based on the OCV _model And the previous Open Circuit Voltage (OCV) _k ) Calculating the current Open Circuit Voltage (OCV) _k+1 ) Wherein the SOC calculation circuit is further configured to be based on the OCV _k+1 Calculating the VSOC _k+1 。

11. The apparatus of claim 9, wherein the device comprises a plurality of sensors,

the battery resistance component includes an equivalent series resistance component and a resistance component in an RC network, the open circuit voltage calculation circuit further configured to calculate the OCV of the battery based on the current measurement, the voltage measurement, the equivalent series resistance component value, and a resistance component value in the RC network _model 。

12. The apparatus of claim 9, wherein the device comprises a plurality of sensors,

the battery resistance component includes an equivalent series resistance component and a transient resistance component, and the open circuit voltage calculation circuit is further configured to calculate the OCV of the battery based on the current measurement, the voltage measurement, the equivalent series resistance component value, and the transient resistance component value _model 。

13. The apparatus of claim 9, wherein the device comprises a plurality of sensors,

the SOC adaptation circuit is further configured to allocate at the VSOC _k+1 And the CCSOC _k+1 Weight on to calculate the SOC _k+1 The weight depends on the SOC confidence and the current measurement of the battery.

14. The apparatus of claim 9, wherein the device comprises a plurality of sensors,

the SOC adaptation circuit is further configured to obtain the VSOC _k+1 And the CCSOC is connected with _k+1 Is a difference in (2); based on the sum of SOC error gains generated from the differenceThe CCSOC _k+1 Calculating the SOC _k+1 The SOC error gain is dependent on SOC confidence and a current measurement of the battery.

15. The apparatus of claim 9, wherein the device comprises a plurality of sensors,

the OCV calculation circuit is further configured to receive a current temperature measurement of the battery and calculate the OCV of the battery based on the temperature measurement _model Wherein the battery model is further used to characterize the temperature measurement and the OCV of the battery _model Relationship between them.

16. A system for calculating a state of charge (SOC) of a battery, the system comprising:

a current sensor configured to measure a current value of the current battery;

a voltage sensor configured to measure a current voltage value of the battery; and

an SOC computing device comprising:

a battery model device configured to receive a current value of the battery and a voltage value of the battery to generate a model-based Open Circuit Voltage (OCV) of the battery _model ) The method comprises the steps of carrying out a first treatment on the surface of the And

a control circuit configured to be based on the OCV _model Calculating a current voltage-based state of charge (VSOC _k+1 ) Receives the previous state of charge (SOC _k ) And based on the SOC _k Calculating a current state of charge based on coulomb counting (CCSOC _k+1 ) And based on the VSOC _k+1 And the CCSOC _k+1 Calculating the current state of charge (SOC _k+1 )。

17. The apparatus of claim 16, wherein the device comprises a plurality of sensors,

the control circuit is further configured to receive a previous Open Circuit Voltage (OCV) _k ) The method comprises the steps of carrying out a first treatment on the surface of the Based on the OCV _model And the OCV _k Calculating the current Open Circuit Voltage (OCV) _k+1 ) And based on the OCV _k+1 Calculating the VSOC _k+1 。

18. The apparatus of claim 16, wherein the device comprises a plurality of sensors,

the battery model includes an equivalent series resistance component and a transient resistance component, the battery model device further configured to calculate the OCV of the battery based on the current value, the voltage value, the equivalent series resistance component value, and a transient resistance component value _model 。

19. The apparatus of claim 16, wherein the device comprises a plurality of sensors,

the control circuit is further configured to control the VSOC based on the allocation _k+1 And the CCSOC _k+1 Weight on to calculate the SOC _k+1 The weight depends on the SOC confidence and the current measurement of the battery.

20. The apparatus of claim 16, wherein the device comprises a plurality of sensors,

the control circuit is further configured to obtain the VSOC _k+1 And the CCSOC is connected with _k+1 Is a difference in (2); based on the SOC error gain generated by the difference and the CCSOC _k+1 Calculating the SOC _k+1 The SOC error gain is dependent on SOC confidence and a current measurement of the battery.