SOC-based electric quantity estimation circuit

Abstract

The utility model relates to the technical field of battery management, in particular to an SOC-based electric quantity estimation circuit, which comprises a DTW-KiBaM model module and a second-order RC equivalent circuit, the input end of the DTW-KiBaM model module is connected with battery constant-current and constant-voltage charging data Uch (t) and environment temperature Tamb data, the output end of the DTW-KiBaM model module is electrically connected with the RC equivalent circuit, and the RC equivalent circuit is electrically connected with the battery constant-current and constant-voltage charging data Uch (t). An ohm internal resistor R < omega >, an electrochemical polarization internal resistor R and a concentration polarization internal resistor R < c > are arranged on the RC equivalent circuit in series. According to the utility model, the corresponding relation between the charging voltage curve and the cycle index is established by using the constant-current and constant-voltage charging data of the battery. And under the condition that the number of cycles of the battery is unknown, the DTW algorithm is used, and the minimum DTW distance between the actual charging voltage data of the battery and the charging voltage data of different cycle aging is calculated by using the actual charging voltage data of the battery, so that the current cycle state of the battery is calculated.

Description

Technical Field

[0001] This utility model relates to a power estimation circuit, and more particularly to a power estimation circuit based on a State of Charge (SOC), belonging to the field of battery management technology. Background Technology

[0002] With the widespread adoption of energy storage devices, obtaining the battery's state of charge (SOC) has become a crucial aspect of battery management. The SOC is calculated by accumulating the amount of electricity charged or discharged, and the calculated SOC is then compensated based on the discharge rate and battery temperature.

[0003] Since the calculation of SOC directly or indirectly depends on the battery's rated total discharge capacity, the rated total discharge capacity of the battery may vary significantly when the actual discharge path is unpredictable or deviates significantly from the predicted discharge path. This leads to a decrease in the accuracy of SOC estimation. Furthermore, as the number of charge and discharge cycles increases, changes in the rated total discharge capacity due to battery aging will also cause deviations in SOC estimation.

[0004] Therefore, it is urgent to improve the SOC-based power estimation circuit to solve the above-mentioned problems. Utility Model Content

[0005] The purpose of this invention is to provide a power estimation circuit based on SOC (State of Charge). It utilizes constant current and constant voltage charging data from the battery to establish a correlation between the charging voltage curve and the number of battery cycles. When the number of battery cycles is unknown, the DTW (Delayed Time Written) algorithm is used to calculate the minimum DTW distance between the battery's actual charging voltage data and the charging voltage data from different aging cycles, thereby calculating the current battery cycle state.

[0006] To achieve the above objectives, the main technical solutions adopted by this utility model include:

[0007] A power estimation circuit based on SOC includes a DTW-KiBaM model module and a second-order RC equivalent circuit. The DTW-KiBaM model module includes a DTW module and a KiBaM module. The input terminal of the DTW-KiBaM model module is connected to the battery constant current and constant voltage charging data Uch(t) and the ambient temperature Tamb data. The output terminal of the DTW-KiBaM model module is electrically connected to the RC equivalent circuit.

[0008] The RC equivalent circuit is equipped with an ohmic internal resistance RΩ, an electrochemical polarization internal resistance Rp, and a concentration polarization internal resistance Rc connected in series.

[0009] Preferably, a capacitor Cp is connected in parallel to the electrochemical polarization internal resistance Rp, and a capacitor Cc is connected in parallel to the concentration polarization internal resistance Rc.

[0010] Preferably, the DTW-KiBaM model module includes an acquisition module, a calculation module, a display module, and a calibration module.

[0011] Preferably, the acquisition module is electrically connected to a battery pack discharge current detector and a discharge temperature detector to acquire the full charge voltage and discharge voltage of the battery pack.

[0012] The calculation module is used to display the currently estimated SOC value.

[0013] Preferably, the calibration module calibrates the SOC value at the corresponding time by acquiring the full charge voltage and discharge voltage of the battery pack from the acquisition module.

[0014] Preferably, a current-limiting constant current circuit is provided on the RC equivalent circuit. The current-limiting constant current circuit includes a transistor Q1 and a field-effect transistor Q2. A resistor Ra and a capacitor Ca are connected in parallel on the field-effect transistor Q2.

[0015] Preferably, a diode D1 and a resistor Rb are provided between the transistor Q1 and the field-effect transistor Q2, and the diode D1 is of type 1N4746.

[0016] Preferably, a capacitor Ce is electrically connected to the transistor Q1, and a resistor Re and a resistor Rf are connected in parallel to the capacitor Ce.

[0017] This utility model has at least the following beneficial effects:

[0018] By utilizing the constant current and constant voltage charging data of the battery, a correlation between the charging voltage curve and the number of cycles is established. When the number of battery cycles is unknown, the DTW algorithm is used to calculate the minimum DTW distance between the actual charging voltage data of the battery and the charging voltage data of different aging cycles, thereby realizing the calculation of the current battery cycle state. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0020] Figure 1 This is a schematic diagram of the present invention;

[0021] Figure 2 This is the circuit diagram of this utility model. Detailed Implementation

[0022] The following will describe in detail the implementation of this application with reference to the accompanying drawings and embodiments, so that the implementation process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0023] like Figures 1-2 As shown, the SOC-based power estimation circuit provided in this embodiment includes a DTW-KiBaM model module and a second-order RC equivalent circuit. The DTW-KiBaM model module includes a DTW module and a KiBaM module. This application consists of three parts: a DTW algorithm, a KiBaM model, and a second-order RC equivalent circuit. The input terminal of the DTW-KiBaM model module is connected to the battery constant current and constant voltage charging data Uch(t) and the ambient temperature Tamb data. The output terminal of the DTW-KiBaM model module is electrically connected to the RC equivalent circuit. The RC equivalent circuit has an ohmic internal resistance RΩ, an electrochemical polarization internal resistance Rp, and a concentration polarization internal resistance Rc connected in series. A capacitor Cp is connected in parallel on the electrochemical polarization internal resistance Rp, and a capacitor Cc is connected in parallel on the concentration polarization internal resistance Rc. Using the battery constant current and constant voltage charging data Uch(t) and the ambient temperature Tamb, the capacity ratio c and diffusion rate k' in the KiBaM model parameters are obtained. Then, based on the KiBaM model... The M-model calculates the unavailable capacity function Cnot(t) of the battery. Using a recursive least squares method with a forgetting factor, online parameter identification is performed through output voltage and operating current to obtain the ohmic internal resistance RΩ, electrochemical polarization internal resistance Rp, concentration polarization internal resistance Rc, and the corresponding polarization capacitances Cp and Cc in the second-order RC model. The SOC calculation matrix is ​​derived by combining Cmax and Cnot(t). Finally, the UKF algorithm is used to estimate the battery SOC. The main idea of ​​the DTW algorithm is based on dynamic programming, extending or shortening two time series to calculate the similarity distance between them, ultimately obtaining the shortest distance between them (i.e., the DTW distance). It was first applied in the field of speech recognition and has since found some application in battery data analysis. Batteries have a relatively stable charging environment, making it easy and accurate to obtain charging data. Based on this characteristic, the constant current and constant voltage charging data of the battery can be used to establish the correspondence between the charging voltage curve and the number of cycles. When the number of battery cycles is unknown, the DTW algorithm is used to calculate the minimum DTW distance between the actual charging voltage data of the battery and the charging voltage data of different aging cycles, thereby realizing the calculation of the current battery cycle state.

[0024] Furthermore, such as Figure 2 As shown, the DTW-KiBaM model module includes a data acquisition module, a calculation module, a display module, and a calibration module. The data acquisition module is electrically connected to a battery pack discharge current detector and a discharge temperature detector, which are used to acquire the full charge voltage and discharge voltage of the battery pack.

[0025] The calculation module is used to display the current estimated SOC value. It uses the weighted value of the pre-configured full characteristic discharge conditions of the battery pack and the preset rated total discharge capacity of the battery pack, and adopts the weighted ampere-hour integration method to calculate the equivalent rated remaining capacity of the battery at this moment, thereby estimating the current SOC.

[0026] The calibration module calibrates the SOC value at the corresponding moment by acquiring the full charge voltage and discharge voltage of the battery pack from the acquisition module.

[0027] Furthermore, such as Figure 2 As shown, a current-limiting constant current circuit is set on the RC equivalent circuit. The current-limiting constant current circuit includes a transistor Q1 and a field-effect transistor Q2. A resistor Ra and a capacitor Ca are connected in parallel on the field-effect transistor Q2. A diode D1 and a resistor Rb are placed between the transistor Q1 and the field-effect transistor Q2. The diode D1 is a 1N4746. A capacitor Ce is electrically connected to the transistor Q1. A resistor Re and a resistor Rf are connected in parallel on the capacitor Ce. By combining the current-limiting and constant current circuits, more complex circuit functions can be achieved. For example, a constant current source and a current-limiting element can be combined to form a current source to drive the components in the circuit. This current source can provide a fixed current output, making the components in the circuit work more stably and reliably. In addition, the current-limiting constant current circuit can also be used to achieve the stability and reliability of the voltage source by precisely controlling the current to ensure the stability of the voltage output.

[0028] like Figures 1-2 As shown, the principle of the SOC-based power estimation circuit provided in this embodiment is as follows:

[0029] The DTW-KiBaM model module's input is connected to the battery's constant current / constant voltage charging data Uch(t) and ambient temperature Tamb data. The output is electrically connected to an RC equivalent circuit. The RC equivalent circuit contains an ohmic internal resistance RΩ, an electrochemical polarization internal resistance Rp, and a concentration polarization internal resistance Rc connected in series. A capacitor Cp is connected in parallel across the electrochemical polarization internal resistance Rp, and a capacitor Cc is connected in parallel across the concentration polarization internal resistance Rc. Using the battery's constant current / constant voltage charging data Uch(t) and ambient temperature Tamb, the capacity ratio c and diffusion rate k' in the KiBaM model parameters are obtained. Then, based on the KiBaM model, the battery's unusable capacity function Cnot(t) is calculated. A recursive least squares method with a forgetting factor is used to perform online parameter comparison using the output voltage and operating current. The system identifies the ohmic internal resistance RΩ, electrochemical polarization internal resistance Rp, concentration polarization internal resistance Rc, and corresponding polarization capacitances Cp and Cc in the second-order RC model. Combining Cmax and Cnot(t), the SOC calculation matrix is ​​derived. Finally, the UKF algorithm is used to estimate the battery SOC. The DTW algorithm, based on dynamic programming, extends or shortens two time series to calculate their similarity distance, ultimately obtaining the shortest distance (DTW distance). Originally applied in speech recognition, it has also found some application in battery data analysis. Batteries have a relatively stable charging environment, making it easy and accurate to obtain charging data. Based on this characteristic, constant current and constant voltage charging data can be used to establish a correlation between the charging voltage curve and the number of cycles. When the number of battery cycles is unknown, the DTW algorithm is used to calculate the minimum DTW distance between the battery's actual charging voltage data and charging voltage data from different aging cycles, thus calculating the current battery cycle state.

[0030] If certain terms are used in the specification and claims to refer to specific components, those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" as used throughout the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to." "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error.

[0031] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes that element.

[0032] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A power estimation circuit based on SOC, comprising a DTW-KiBaM model module and a second-order RC equivalent circuit, characterized in that, The DTW-KiBaM model module includes a DTW module and a KiBaM module. The input terminal of the DTW-KiBaM model module is connected to the battery constant current and constant voltage charging data Uch(t) and the ambient temperature Tamb data. The output terminal of the DTW-KiBaM model module is electrically connected to the RC equivalent circuit. The RC equivalent circuit is equipped with an ohmic internal resistance RΩ, an electrochemical polarization internal resistance Rp, and a concentration polarization internal resistance Rc connected in series.

2. The power estimation circuit based on SOC according to claim 1, characterized in that: A capacitor Cp is connected in parallel to the electrochemical polarization internal resistance Rp, and a capacitor Cc is connected in parallel to the concentration polarization internal resistance Rc.

3. The power estimation circuit based on SOC according to claim 1, characterized in that: The DTW-KiBaM model module includes an acquisition module, a calculation module, a display module, and a calibration module.

4. The power estimation circuit based on SOC according to claim 3, characterized in that: The acquisition module is electrically connected to a battery pack discharge current detector and a discharge temperature detector, which are used to acquire the full charge voltage and discharge voltage of the battery pack. The calculation module is used to display the currently estimated SOC value.

5. The power estimation circuit based on SOC according to claim 3, characterized in that: The calibration module calibrates the SOC value at the corresponding moment by acquiring the full charge voltage and discharge voltage of the battery pack from the acquisition module.

6. The power estimation circuit based on SOC according to claim 1, characterized in that: The RC equivalent circuit is provided with a current-limiting constant current circuit, which includes a transistor Q1 and a field-effect transistor Q2. A resistor Ra and a capacitor Ca are connected in parallel on the field-effect transistor Q2.

7. The power estimation circuit based on SOC according to claim 6, characterized in that: A diode D1 and a resistor Rb are disposed between the transistor Q1 and the field-effect transistor Q2. The diode D1 is a 1N4746.

8. The power estimation circuit based on SOC according to claim 7, characterized in that: A capacitor Ce is electrically connected to the transistor Q1, and a resistor Re and a resistor Rf are connected in parallel to the capacitor Ce.

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