Electrochemical impedance measuring circuit, battery management system thereof, battery pack and electric equipment

Abstract

The utility model discloses an electrochemical impedance measurement circuit, a battery management system thereof, a battery pack and electric equipment. The electrochemical impedance measurement circuit comprises a sampling circuit, an excitation circuit and a controller, the sampling circuit is electrically connected with the battery module and the controller and is used for acquiring an internal total voltage value of the battery module; the controller is electrically connected with the excitation circuit, and outputs a first pulse control signal to the excitation circuit according to the internal total voltage value of the battery module; the excitation circuit responds to the first pulse control signal and controls the external power supply to charge the battery module with pulse current with the frequency corresponding to the first pulse control signal; the sampling circuit collects a battery cell excitation voltage value and a battery cell excitation current value of the battery module in the process that the battery module is charged by the pulse current with the frequency corresponding to the first pulse control signal; and the controller determines the electrochemical impedance of the battery module under the frequency corresponding to the first pulse control signal according to the cell excitation voltage value and the cell excitation current value of the battery module.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to an electrochemical impedance measurement circuit and its battery management system, battery pack, and electrical equipment. Background Technology

[0002] The cell impedance of a battery reflects its internal electrochemical characteristics and is of great significance in research, analysis, and practical applications. For example, by measuring the cell impedance and constructing an electrochemical impedance spectroscopy (EIS), high-precision battery state estimation that delves into the battery mechanism can be achieved.

[0003] However, the electrochemical impedance of lithium batteries is currently generally determined by PID control of the difference between the actual sampling signal and the reference sinusoidal signal in the measurement loop of the electrochemical system. The output control signal is then introduced into the measurement loop as an excitation signal, so that the actual sampling signal of the measurement loop gradually matches the reference sinusoidal signal. This is equivalent to applying a sinusoidal AC excitation signal to the electrochemical system under test, and the corresponding response signal is also an AC signal. The electrochemical impedance of the electrochemical system can be calculated based on this AC response signal. However, this method requires the introduction of an AC signal generator and the design of a feedback control circuit, which makes the system design complex and requires additional electronic components, increasing costs. Utility Model Content

[0004] In view of the above problems, this application provides an electrochemical impedance measurement circuit and its battery management system, battery pack and electrical device, which can solve the problem that the current lithium battery electrochemical impedance measurement requires the introduction of AC signal generator and the design of feedback control circuit, which makes the system design complicated and requires additional electronic components to increase costs.

[0005] In a first aspect, this application provides an electrochemical impedance measurement circuit, including a sampling circuit, an excitation circuit, and a controller. The sampling circuit is electrically connected to a battery module and the controller, and is used to collect the total internal voltage value of the battery module and transmit the total internal voltage value of the battery module to the controller. The controller is electrically connected to the excitation circuit and is used to output a first pulse control signal to the excitation circuit based on the total internal voltage value of the battery module. The excitation circuit is electrically connected to an external power supply and the battery module, and is used to control the external power supply to charge the battery module with a pulse current at the frequency corresponding to the first pulse control signal in response to the first pulse control signal. The sampling circuit is also used to collect the cell excitation voltage value and cell excitation current value of the battery module during the charging process of the battery module with the pulse current at the frequency corresponding to the first pulse control signal, and transmit the cell excitation voltage value and cell excitation current value of the battery module to the controller. The controller is also used to determine the electrochemical impedance of the battery module at the frequency corresponding to the first pulse control signal based on the cell excitation voltage value and cell excitation current value of the battery module.

[0006] The electrochemical impedance spectroscopy (EIS) measurement circuit described above transmits a first pulse control signal to the excitation circuit via a controller. This causes the excitation circuit to control an external power supply to charge the battery module with a pulse current at the frequency corresponding to the first pulse control signal, achieving excitation at a specific driving frequency. Then, a sampling circuit acquires the cell excitation voltage and current values ​​of the battery module under the excitation conditions. Based on these values, the EIS of the battery module at the frequency corresponding to the first pulse control signal is determined. This allows for EIS measurement of the battery module at a specific driving frequency using a simple excitation circuit and a special pulse control signal, simplifying the system circuitry and saving on component costs. Furthermore, this solution charges the battery module with a pulse current at the frequency corresponding to the first pulse control signal, ensuring that the polarization voltage of the battery module fluctuates within a certain range during charging. This prevents the polarization voltage from continuously increasing and affecting battery performance and capacity, thus guaranteeing the performance and capacity of the battery module.

[0007] In some embodiments, the excitation circuit includes a DC-DC converter and a controllable switch. A first terminal of the controllable switch is electrically connected to a sampling circuit, and a second terminal of the controllable switch is electrically connected to both the first terminal of the DC-DC converter and the battery module. A control terminal of the controllable switch is electrically connected to a controller, and the second terminal of the DC-DC converter is electrically connected to an external power source. The DC-DC converter is used to convert the output voltage signal from the external power source into a DC-DC converter and output an excitation voltage signal, wherein the voltage value corresponding to the excitation voltage signal is greater than the total internal voltage value. The controller is used to output a first pulse control signal to the controllable switch. The controllable switch, in response to the first pulse control signal, performs an on / off operation at the frequency corresponding to the first pulse control signal, controlling the frequency of the excitation voltage signal output by the DC-DC converter to the battery module, thereby charging the battery module with a pulse current at the frequency corresponding to the first pulse control signal.

[0008] In the above implementation, this solution forms an excitation circuit using a DC-DC converter and a switch. The on / off frequency of the switch is controlled by a first pulse control signal to enable the external power supply to charge the battery module with a pulse current corresponding to the frequency of the first pulse control signal. In this way, the DC-DC converter combined with the controllable switch can quickly generate pulse current excitation for the battery module without the need to introduce an AC signal generator or design a feedback control circuit, thereby simplifying the system circuit, maximizing the reuse of the original hardware design, and reducing costs.

[0009] In some embodiments, the controller is electrically connected to the DC-DC converter; the controller is used to send a conversion signal to the DC-DC converter; the DC-DC converter is used to convert the output voltage signal of the external power supply into a DC-DC converter and output an excitation voltage signal in response to the conversion signal.

[0010] In the above implementation, this solution uses a controller to connect and control the DC-DC converter, thereby controlling the switching of the DC-DC converter and controlling the conversion of the excitation voltage signal. This ensures that the excitation voltage signal is always slightly greater than the total internal voltage of the battery module, thus enabling the charging of battery module A and improving the controllability and adjustability of the measurement.

[0011] In some embodiments, the electrochemical impedance measurement circuit further includes a communication bus, through which the controller is electrically connected to the control terminal of the controllable switch and the DC converter, respectively.

[0012] In the above implementation, the controller is electrically connected to the control terminal of the controllable switch and the DC converter via separate communication buses, thereby improving the control efficiency of the controllable switch and the DC converter.

[0013] In some embodiments, the controllable switch may include a field-effect transistor.

[0014] In the above implementation scheme, the controllable switch is designed using a field-effect transistor. Compared with the shortcomings of traditional relay switching, such as slow speed and short switching life, it can generate pulse current excitation of different frequencies to the battery module very quickly, while retaining and reusing the original hardware design to the maximum extent and reducing costs.

[0015] In some embodiments, the sampling circuit includes an integrated circuit chip and a shunt. The integrated circuit chip is electrically connected to the controller and is electrically connected to the battery module and the excitation circuit respectively through the shunt. The integrated circuit chip is used to differentially sample the internal total voltage value of the battery module through the shunt and transmit the internal total voltage value of the battery module to the controller. The integrated circuit chip is also used to differentially sample the cell excitation voltage value of the battery module through the shunt during the charging process of the battery module by the pulse current at the frequency corresponding to the first pulse control signal, and to calculate the cell excitation current value of the battery module by measuring the differential voltage on both sides of the shunt.

[0016] In some embodiments, the controller is further configured to send a stop excitation signal to the excitation circuit; the excitation circuit is configured to control the external power supply to stop charging the battery module in response to the stop excitation signal; the sampling circuit is further configured to collect the cell voltage value of the battery module under the condition that the external power supply stops supplying power, and transmit the cell voltage value to the controller; the controller is further configured to determine whether the cell voltage of the battery module is stable based on the cell voltage value of the battery module; if the cell voltage of the battery module is determined to be stable, send a second pulse control signal to the excitation circuit; the excitation circuit is further configured to control the external power supply to charge the battery module with a pulse current at the frequency corresponding to the second pulse control signal in response to the second pulse control signal; the sampling circuit is further configured to collect the second cell excitation voltage value and the second cell excitation current value of the battery module during the charging process of the battery module with the pulse current at the frequency corresponding to the second pulse control signal, and transmit the second cell excitation voltage value and the second cell excitation current value to the controller; the controller is further configured to determine the electrochemical impedance of the battery module at the frequency corresponding to the second pulse control signal based on the second cell excitation voltage value and the second cell excitation current value of the battery module.

[0017] In the above-described implementation, this solution can adjust the frequency of the pulse control signal of the drive excitation circuit to achieve electrochemical impedance measurement at different pulse frequencies. This allows the solution to obtain the electrochemical impedance of the battery module at different pulse frequencies by continuously adjusting the pulse frequency, thereby forming the electrochemical impedance spectrum of the battery module. Therefore, this solution can achieve the electrochemical impedance spectrum measurement of the battery module through a simple electrochemical impedance measurement circuit, thereby simplifying the circuit and reducing costs.

[0018] In a second aspect, this application provides a battery management system that includes an electrochemical impedance measurement circuit according to any embodiment of the first aspect.

[0019] The battery management system designed above, incorporating the electrochemical impedance measurement circuit described earlier, transmits a first pulse control signal to the excitation circuit via a controller. This causes the excitation circuit to control an external power supply to charge the battery module with a pulse current at the frequency corresponding to the first pulse control signal, achieving excitation at a specific drive frequency. Then, a sampling circuit acquires the cell excitation voltage and current values ​​of the battery module under the excitation conditions. Based on these values, the electrochemical impedance of the battery module at the frequency corresponding to the first pulse control signal is determined. Thus, the electrochemical impedance measurement of the battery module at a specific drive frequency is achieved through a simple excitation circuit and a special pulse control signal, simplifying the system circuitry and saving on component costs. Furthermore, this solution charges the battery module with a pulse current at the frequency corresponding to the first pulse control signal, ensuring that the polarization voltage of the battery module fluctuates within a certain range during charging. This prevents the polarization voltage from continuously increasing and affecting battery performance and capacity, thereby guaranteeing the performance and capacity of the battery module.

[0020] Thirdly, this application provides a battery pack, including a battery module, an external power supply, and an electrochemical impedance measurement circuit as described in any embodiment of the first aspect. The sampling circuit is electrically connected to the battery module and the controller, the controller is electrically connected to the excitation circuit and the battery module, and the excitation circuit is electrically connected to the external power supply.

[0021] The battery pack designed above, containing the electrochemical impedance measurement circuit described above, transmits a first pulse control signal to the excitation circuit via a controller. This causes the excitation circuit to control an external power supply to charge the battery module with a pulse current at the frequency corresponding to the first pulse control signal, achieving excitation at a specific driving frequency. Then, a sampling circuit collects the cell excitation voltage and current values ​​of the battery module under the excitation conditions. Based on these values, the electrochemical impedance of the battery module at the frequency corresponding to the first pulse control signal is determined. Thus, the electrochemical impedance measurement of the battery module at a specific driving frequency is achieved through a simple excitation circuit and a special pulse control signal, simplifying the system circuitry and saving device costs. Furthermore, this solution charges the battery module with a pulse current at the frequency corresponding to the first pulse control signal, ensuring that the polarization voltage of the battery module fluctuates within a certain range during charging. This prevents the polarization voltage from continuously increasing and affecting battery performance and capacity, thereby guaranteeing the performance and capacity of the battery module.

[0022] Fourthly, this application provides an electrical device that includes the battery pack described in the third aspect.

[0023] The aforementioned electrical device, containing the battery pack described above, uses a controller to transmit a first pulse control signal to the excitation circuit. This causes the excitation circuit to control an external power supply to charge the battery module with a pulse current at the frequency corresponding to the first pulse control signal, achieving excitation at a specific driving frequency. A sampling circuit then collects the cell excitation voltage and current values ​​of the battery module under these excitation conditions. Based on these values, the electrochemical impedance of the battery module at the frequency corresponding to the first pulse control signal is determined. This simplifies the system circuitry and reduces component costs by achieving electrochemical impedance measurement of the battery module at a specific driving frequency using a simple excitation circuit and a special pulse control signal. Furthermore, this design uses a pulse current at the frequency corresponding to the first pulse control signal to charge the battery module, ensuring that the polarization voltage of the battery module fluctuates within a certain range during charging. This prevents the polarization voltage from continuously increasing and affecting battery performance and capacity, thus guaranteeing the performance and capacity of the battery module.

[0024] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0025] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0026] Figure 1 A first circuit diagram of the electrochemical impedance measurement circuit provided in the embodiments of this application;

[0027] Figure 2 A second circuit diagram of the electrochemical impedance measurement circuit provided in the embodiments of this application;

[0028] Figure 3 A schematic diagram of the third circuit of the electrochemical impedance measurement circuit provided in the embodiments of this application;

[0029] Figure 4 A fourth circuit diagram of the electrochemical impedance measurement circuit provided in the embodiments of this application;

[0030] Figure 5The fifth circuit diagram of the electrochemical impedance measurement circuit provided in the embodiments of this application.

[0031] Icons: 1-Electrochemical impedance measurement circuit; A-Battery module; B-External power supply; 10-Sampling circuit; 110-Integrated circuit chip; 120-Shunt unit; 20-Excitation circuit; 210-DC converter; 220-Controllable switch; 30-Controller; 40-Communication bus. Detailed Implementation

[0032] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0034] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0035] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0036] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0037] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0038] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0039] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0040] The cell impedance of a battery reflects its internal electrochemical characteristics and is of great significance in research, analysis, and practical applications. For example, by measuring the cell impedance and constructing an electrochemical impedance spectroscopy (EIS), high-precision battery state estimation that delves into the battery mechanism can be achieved.

[0041] However, the electrochemical impedance of lithium batteries is currently generally determined by PID control of the difference between the actual sampling signal and the reference sinusoidal signal in the measurement loop of the electrochemical system. The output control signal is then introduced into the measurement loop as an excitation signal, so that the actual sampling signal of the measurement loop gradually matches the reference sinusoidal signal. This is equivalent to applying a sinusoidal AC excitation signal to the electrochemical system under test, and the corresponding response signal is also an AC signal. The electrochemical impedance of the electrochemical system can be calculated based on this AC response signal. However, this method requires the introduction of an AC signal generator and the design of a feedback control circuit, which makes the system design complex and requires additional electronic components, increasing costs.

[0042] To address the aforementioned issues, this application designs an electrochemical impedance spectroscopy (EIS) measurement circuit and its battery management system, battery pack, and power device. A controller transmits a first pulse control signal to the excitation circuit, causing the excitation circuit to control an external power supply to charge the battery module with a pulse current at the frequency corresponding to the first pulse control signal, achieving excitation at a specific driving frequency. Then, a sampling circuit collects the cell excitation voltage and current values ​​of the battery module under the excitation conditions. Based on these values, the EIS of the battery module at the frequency corresponding to the first pulse control signal is determined. Thus, the EIS measurement of the battery module at a specific driving frequency is achieved through a simple excitation circuit and a special pulse control signal, simplifying the system circuitry and saving device costs. Furthermore, this solution charges the battery module with a pulse current at the frequency corresponding to the first pulse control signal, ensuring that the polarization voltage of the battery module fluctuates within a certain range during charging. This prevents the polarization voltage from continuously increasing and affecting battery performance and capacity, thereby guaranteeing the performance and capacity of the battery module. Specifically, this solution injects specific driving frequency excitation into the cell module by controlling the output voltage of the external DC-DC converter and the driving frequency of the switching MOSFET, thereby simplifying the system circuit and saving device costs without changing the original circuit structure of the battery management system.

[0043] Based on the above ideas, this application first provides an electrochemical impedance spectroscopy (EIS) measurement circuit, which can measure the electrochemical impedance of battery module A, such as... Figure 1 As shown, the electrochemical impedance measurement circuit includes a sampling circuit 10, an excitation circuit 20, and a controller 30. The sampling circuit 10 is electrically connected to the battery module A and the controller 30, and the excitation circuit 20 is electrically connected to the controller 30, the external power supply B, and the battery module A.

[0044] The electrochemical impedance measurement circuit designed above, the sampling circuit 10 can collect the internal total voltage value of battery module A, and then transmit the internal total voltage value of battery module A to controller 30. The internal total voltage value represents the sum of the battery voltages inside the battery module. The internal total voltage value of the battery module is mainly determined by the rated voltage and capacity of the battery module. The rated voltage of the battery module is the nominal voltage of a single battery cell multiplied by the number of battery cells, and the capacity of the battery module is the capacity of a single battery cell multiplied by the number of parallel cells.

[0045] When the controller 30 obtains the total internal voltage value of the battery module A, the controller 30 outputs a first pulse control signal to the excitation circuit 20 based on the total internal voltage value of the battery module A. Here, pulse refers to a short-lived electrical impulse (voltage or current) signal that is like a pulse and is often used in electronic technology.

[0046] When the excitation circuit 20 receives the first pulse control signal, it responds to the first pulse control signal by controlling the external power supply B to charge the battery module A with a pulse current of the frequency corresponding to the first pulse control signal. The frequency corresponding to the first pulse control signal represents the pulse fluctuation period of the first pulse control signal.

[0047] In this design, during the charging and discharging process of battery module A (lithium-ion battery), incomplete electrochemical reactions due to internal resistance cause the battery voltage to deviate from its theoretical value, resulting in polarization voltage. Therefore, when external power source B charges battery module A, the polarization voltage gradually increases due to the charging effect. Increased polarization voltage leads to deterioration in battery performance and greater capacity loss. To avoid the impact of polarization voltage on the battery, this solution controls the external power source B to charge the battery module with a pulse current at a frequency corresponding to the first pulse control signal. This pulse current at a specific frequency causes battery module A to disconnect from charging after a certain charging time, and then restart charging after a further disconnection. This ensures that after the polarization voltage reaches a certain level during charging, it gradually decreases again after disconnection, and then reconnects to charging once the polarization voltage drops to a certain level. This keeps the polarization voltage fluctuating within a certain range, preventing it from continuously increasing and affecting battery performance and capacity.

[0048] During the charging process of battery module A by external power supply B with a pulse current at the frequency corresponding to the first pulse control signal, sampling circuit 10 can collect the cell excitation voltage and cell excitation current values ​​of battery module A, and transmit them to controller 30. Controller 30 can determine the electrochemical impedance of battery module A at the frequency corresponding to the first pulse control signal based on the cell excitation voltage and cell excitation current values ​​of battery module A. Specifically, the cell excitation voltage value represents the voltage value of a single battery cell in battery module A when charged by a pulse current at the frequency corresponding to the first pulse control signal; the cell excitation current value represents the current value of a single battery cell in battery module A when charged by a pulse current at the frequency corresponding to the first pulse control signal; and the electrochemical impedance represents the impedance of the electrode when the electrode system is disturbed by an AC signal of waveform voltage (current), resulting in a corresponding current (voltage) response signal.

[0049] Specifically, the controller 30 can be pre-configured with an electrochemical impedance calculation method. Given the cell excitation voltage and current values ​​of battery module A transmitted by the sampling circuit, the electrochemical impedance of battery module A at the frequency corresponding to the first pulse control signal can be calculated using the configured electrochemical impedance calculation method. This electrochemical impedance calculation method can specifically employ a fast Fourier transform to calculate the electrochemical impedance, or other methods based on the cell excitation voltage and current values ​​can be used; the specific method is not limited in this application.

[0050] The electrochemical impedance spectroscopy (EIS) measurement circuit described above transmits a first pulse control signal to the excitation circuit via a controller. This causes the excitation circuit to control an external power supply to charge the battery module with a pulse current at the frequency corresponding to the first pulse control signal, achieving excitation at a specific driving frequency. Then, a sampling circuit acquires the cell excitation voltage and current values ​​of the battery module under the excitation conditions. Based on these values, the EIS of the battery module at the frequency corresponding to the first pulse control signal is determined. This allows for EIS measurement of the battery module at a specific driving frequency using a simple excitation circuit and a special pulse control signal, simplifying the system circuitry and saving on component costs. Furthermore, this solution charges the battery module with a pulse current at the frequency corresponding to the first pulse control signal, ensuring that the polarization voltage of the battery module fluctuates within a certain range during charging. This prevents the polarization voltage from continuously increasing and affecting battery performance and capacity, thus guaranteeing the performance and capacity of the battery module.

[0051] In an optional implementation of this embodiment, as one possible implementation, such as Figure 2 As shown, the excitation circuit 20 designed in this scheme may include a DC-DC converter 210 and a controllable switch 220. The first terminal of the controllable switch 220 is electrically connected to the sampling circuit 10, and the second terminal of the controllable switch 220 is electrically connected to the first terminal of the DC-DC converter 210 and the battery module A, respectively. The control terminal of the controllable switch 220 is electrically connected to the controller 30, and the second terminal of the DC-DC converter 210 is electrically connected to the external power supply B. Specifically, the DC-DC converter 210 may be a DC-DC converter, and the controllable switch 220 may be a field-effect transistor, such as a metal-oxide-semiconductor field-effect transistor (MOSFET), etc.

[0052] In the electrochemical impedance measurement circuit designed above, this scheme forms an excitation circuit 20 through a DC-DC converter 210 and a controllable switch 220. In this case, the DC-DC converter 210 can convert the output voltage signal of the external power supply and output an excitation voltage signal. The voltage value corresponding to this excitation voltage signal is greater than the total internal voltage value of the battery module A. When the controller 30 obtains the total internal voltage value of the battery module A, the controller 30 can output a first pulse control signal to the controllable switch 220. The controllable switch 220 can respond to the first pulse control signal and perform a conduction / cutoff operation at the frequency corresponding to the first pulse control signal. That is, the controllable switch 220 is turned on for a period of time and then turned off, and then turned on again after a period of cutoff. Thus, when the controllable switch 220 is turned on, the excitation voltage signal converted and output by the DC-DC converter 210 charges the battery module A. When the controllable switch 220 is turned off, the excitation voltage signal converted and output by the DC-DC converter 210 stops charging the battery module A. Thus, the external power supply B charges the battery module with a pulse current at the frequency corresponding to the first pulse control signal. The first pulse control signal can be a preset pulse signal of a specific frequency.

[0053] The electrochemical impedance measurement circuit designed above uses a DC-DC converter and a switch to form an excitation circuit. The on / off frequency of the switch is controlled by a first pulse control signal to enable the external power supply to charge the battery module with a pulse current corresponding to the frequency of the first pulse control signal. In this way, the DC-DC converter combined with the controllable switch can quickly generate pulse current excitation for the battery module without the need to introduce an AC signal generator or design a feedback control circuit. This simplifies the system circuit, maximizes the reuse of the original hardware design, and reduces costs.

[0054] In one of the optional embodiments of this implementation, as a specific implementation method, such as Figure 3 As shown, the controller 30 can be electrically connected to the control terminal of the controllable switch 220 and the DC converter 210 via the communication bus 40. In this case, the controller 30 can adjust the voltage value corresponding to the excitation voltage signal output by the DC converter 210 so that the excitation voltage signal output by the DC converter 210 is always slightly greater than the total internal voltage value of the battery module A, thereby enabling the excitation voltage signal output by the DC converter 210 to charge the battery module A.

[0055] In an optional implementation of this embodiment, such as Figure 4 As shown, the sampling circuit 10 designed in this scheme may specifically include an integrated circuit chip 110 and a shunt 120. The integrated circuit chip 110 is electrically connected to the controller 30, and the integrated circuit chip 110 is electrically connected to the battery module A and the excitation circuit 20 through the shunt 120.

[0056] In the electrochemical impedance measurement circuit designed above, the integrated circuit chip 110 can differentially sample the total internal voltage value of the battery module through the shunt 120 and transmit the total internal voltage value of the battery module to the controller 30. Furthermore, during the charging process of the battery module by the pulse current corresponding to the frequency of the first pulse control signal, the integrated circuit chip 110 differentially samples the cell excitation voltage value of the battery module through the shunt 120 and calculates the cell excitation current value of the battery module by measuring the differential voltage across the shunt 120. The calculation of the cell excitation current value of the battery module based on the differential voltage can be achieved using any currently available conversion method based on differential voltage to current value.

[0057] Specifically, as shown in the figure, the integrated circuit chip 110 can measure the total internal voltage of the battery module A and sample the cell excitation voltage of the battery module during the charging process of the battery module by the pulse current at the frequency corresponding to the first pulse control signal through a 4-channel differential sampling channel.

[0058] In an optional embodiment of this scheme, the controller 30 can also send a stop excitation signal to the excitation circuit 20. In response to the stop excitation signal, the excitation circuit 20 controls the external power supply B to stop charging the battery module A. Specifically, the controller 30 can send a stop excitation signal to the controllable switch 220. In response to the stop excitation signal, the controllable switch 220 executes a cutoff state, thereby controlling the external power supply B to stop charging the battery module A.

[0059] When the external power supply is interrupted, the sampling circuit 10 can collect the cell voltage value of the battery module and then transmit the cell voltage value to the controller 30. The controller 30 can determine whether the cell voltage of the battery module is stable based on the cell voltage value. If the cell voltage value of the battery module is determined to be stable, a second pulse control signal is sent to the excitation circuit 20. However, when the external power supply is interrupted, the cell voltage of the battery module will fluctuate for a certain period of time. Since the cell voltage value of the battery module needs to remain stable before the next frequency of electrochemical impedance measurement can be performed, this solution requires a determination of whether the cell voltage of the battery module is stable. Specifically, this solution can determine whether the cell voltage of the battery module remains unchanged or whether the cell voltage value of the battery module remains within a stable numerical range. If the cell voltage remains unchanged or remains within a stable numerical range, the cell voltage of the battery module is determined to be stable.

[0060] The excitation circuit 20 can respond to the second pulse control signal and control the external power supply B to charge the battery module with a pulse current at the frequency corresponding to the second pulse control signal; the sampling circuit 10 collects the second cell excitation voltage value and the second cell excitation current value of the battery module A during the charging process of the pulse current at the frequency corresponding to the second pulse control signal, and transmits the second cell excitation voltage value and the second cell excitation current value to the controller; the controller 30 determines the electrochemical impedance of the battery module A at the frequency corresponding to the second pulse control signal based on the second cell excitation voltage value and the second cell excitation current value of the battery module A.

[0061] In the above-described implementation, this solution can adjust the frequency of the pulse control signal of the drive excitation circuit to achieve electrochemical impedance measurement at different pulse frequencies. This allows the solution to obtain the electrochemical impedance of the battery module at different pulse frequencies by continuously adjusting the pulse frequency, thereby forming the electrochemical impedance spectrum of the battery module. Therefore, this solution can achieve the electrochemical impedance spectrum measurement of the battery module through a simple electrochemical impedance measurement circuit, thereby simplifying the circuit and reducing costs.

[0062] In an optional embodiment of this example, in addition to sampling through a sampling circuit, the total internal voltage value of battery module A can also be calculated in advance based on the rated voltage and capacity of battery module A, and then stored in controller 30. Controller 30 can obtain the total internal voltage value of battery module A by calling the stored total internal voltage value.

[0063] This application also provides a battery management system that includes an electrochemical impedance measurement circuit of any of the optional embodiments described above.

[0064] The battery management system designed above, incorporating the electrochemical impedance measurement circuit described earlier, transmits a first pulse control signal to the excitation circuit via a controller. This causes the excitation circuit to control an external power supply to charge the battery module with a pulse current at the frequency corresponding to the first pulse control signal, achieving excitation at a specific drive frequency. Then, a sampling circuit acquires the cell excitation voltage and current values ​​of the battery module under the excitation conditions. Based on these values, the electrochemical impedance of the battery module at the frequency corresponding to the first pulse control signal is determined. Thus, the electrochemical impedance measurement of the battery module at a specific drive frequency is achieved through a simple excitation circuit and a special pulse control signal, simplifying the system circuitry and saving on component costs. Furthermore, this solution charges the battery module with a pulse current at the frequency corresponding to the first pulse control signal, ensuring that the polarization voltage of the battery module fluctuates within a certain range during charging. This prevents the polarization voltage from continuously increasing and affecting battery performance and capacity, thereby guaranteeing the performance and capacity of the battery module.

[0065] This application also provides a battery pack, such as Figure 5 As shown, the battery pack includes a battery module A, an external power supply B, and an electrochemical impedance measurement circuit 1 of any of the optional embodiments described above. The sampling circuit 10 is electrically connected to the battery module A and the controller 30, respectively. The controller 30 is electrically connected to the excitation circuit 20 and the battery module A, respectively. The excitation circuit 20 is electrically connected to the external power supply B.

[0066] The battery pack designed above, containing the electrochemical impedance measurement circuit described above, transmits a first pulse control signal to the excitation circuit via a controller. This causes the excitation circuit to control an external power supply to charge the battery module with a pulse current at the frequency corresponding to the first pulse control signal, achieving excitation at a specific driving frequency. Then, a sampling circuit collects the cell excitation voltage and current values ​​of the battery module under the excitation conditions. Based on these values, the electrochemical impedance of the battery module at the frequency corresponding to the first pulse control signal is determined. Thus, the electrochemical impedance measurement of the battery module at a specific driving frequency is achieved through a simple excitation circuit and a special pulse control signal, simplifying the system circuitry and saving device costs. Furthermore, this solution charges the battery module with a pulse current at the frequency corresponding to the first pulse control signal, ensuring that the polarization voltage of the battery module fluctuates within a certain range during charging. This prevents the polarization voltage from continuously increasing and affecting battery performance and capacity, thereby guaranteeing the performance and capacity of the battery module.

[0067] This application also provides an electrical device that includes the battery pack described above, wherein the electrical device includes, but is not limited to, any one or more of electrical devices such as automobiles, trains, spacecraft, airships, submarines, and airplanes.

[0068] The aforementioned electrical device, containing the battery pack described above, uses a controller to transmit a first pulse control signal to the excitation circuit. This causes the excitation circuit to control an external power supply to charge the battery module with a pulse current at the frequency corresponding to the first pulse control signal, achieving excitation at a specific driving frequency. A sampling circuit then collects the cell excitation voltage and current values ​​of the battery module under these excitation conditions. Based on these values, the electrochemical impedance of the battery module at the frequency corresponding to the first pulse control signal is determined. This simplifies the system circuitry and reduces component costs by achieving electrochemical impedance measurement of the battery module at a specific driving frequency using a simple excitation circuit and a special pulse control signal. Furthermore, this design uses a pulse current at the frequency corresponding to the first pulse control signal to charge the battery module, ensuring that the polarization voltage of the battery module fluctuates within a certain range during charging. This prevents the polarization voltage from continuously increasing and affecting battery performance and capacity, thus guaranteeing the performance and capacity of the battery module.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An electrochemical impedance spectroscopy circuit, characterized in that, The circuit includes a sampling circuit, an excitation circuit, and a controller; The sampling circuit is electrically connected to the battery module and the controller, and is used to collect the internal total voltage value of the battery module and transmit the internal total voltage value of the battery module to the controller. The controller, which is electrically connected to the excitation circuit, is used to output a first pulse control signal to the excitation circuit according to the total internal voltage value of the battery module; The excitation circuit is electrically connected to the external power supply and the battery module, and is used to control the external power supply to charge the battery module with a pulse current of the frequency corresponding to the first pulse control signal in response to the first pulse control signal. The sampling circuit is also used to collect the cell excitation voltage value and cell excitation current value of the battery module during the charging process of the battery module by the pulse current at the frequency corresponding to the first pulse control signal, and to transmit the cell excitation voltage value and cell excitation current value of the battery module to the controller. The controller is further configured to determine the electrochemical impedance of the battery module at the frequency corresponding to the first pulse control signal based on the cell excitation voltage and cell excitation current of the battery module.

2. The circuit according to claim 1, characterized in that, The excitation circuit includes a DC-DC converter and a controllable switch. The first terminal of the controllable switch is electrically connected to the sampling circuit. The second terminal of the controllable switch is electrically connected to the first terminal of the DC-DC converter and the battery module, respectively. The control terminal of the controllable switch is electrically connected to the controller. The second terminal of the DC-DC converter is electrically connected to the external power supply. The DC-DC converter is used to convert the output voltage signal of the external power supply into a DC-DC converter and output an excitation voltage signal, wherein the voltage value corresponding to the excitation voltage signal is greater than the total internal voltage value. The controller is used to output the first pulse control signal to the controllable switch; The controllable switch is used to respond to the first pulse control signal, perform a conduction / cutoff operation at the frequency corresponding to the first pulse control signal, control the frequency of the excitation voltage signal output by the DC converter to the battery module, and realize charging of the battery module with a pulse current at the frequency corresponding to the first pulse control signal.

3. The circuit according to claim 2, characterized in that, The controller is electrically connected to the DC-DC converter; The controller is used to send conversion signals to the DC-DC converter; The DC-DC converter is used to convert the output voltage signal of the external power supply into a DC-DC converter and output an excitation voltage signal in response to the conversion signal.

4. The circuit according to claim 3, characterized in that, The electrochemical impedance measurement circuit also includes a communication bus, through which the controller is electrically connected to the control terminal of the controllable switch and the DC converter.

5. The circuit according to claim 2, characterized in that, The controllable switch includes a field-effect transistor.

6. The circuit according to claim 1, characterized in that, The sampling circuit includes an integrated circuit chip and a shunt. The integrated circuit chip is electrically connected to the controller, and the integrated circuit chip is electrically connected to the battery module and the excitation circuit respectively through the shunt. The integrated circuit chip is used to differentially sample the internal total voltage value of the battery module through the shunt and transmit the internal total voltage value of the battery module to the controller; The integrated circuit chip is also used to differentially sample the cell excitation voltage value of the battery module through the shunt during the charging process of the battery module by the pulse current corresponding to the frequency of the first pulse control signal, and to calculate the cell excitation current value of the battery module by measuring the differential voltage on both sides of the shunt.

7. The circuit according to claim 1, characterized in that, The controller is also configured to send a stop excitation signal to the excitation circuit; The excitation circuit is used to control the external power supply to stop charging the battery module in response to the stop excitation signal; The sampling circuit is also used to collect the cell voltage value of the battery module when the external power supply stops supplying power, and transmit the cell voltage value to the controller; The controller is further configured to determine whether the cell voltage of the battery module is stable based on the cell voltage value of the battery module; and to send a second pulse control signal to the excitation circuit if the cell voltage of the battery module is determined to be stable. The excitation circuit is also used to control the external power supply to charge the battery module with a pulse current of the frequency corresponding to the second pulse control signal in response to the second pulse control signal. The sampling circuit is also used to collect the second cell excitation voltage value and the second cell excitation current value of the battery module during the charging process of the battery module by the pulse current at the frequency corresponding to the second pulse control signal, and to transmit the second cell excitation voltage value and the second cell excitation current value to the controller. The controller is further configured to determine the electrochemical impedance of the battery module at the frequency corresponding to the second pulse control signal based on the second cell excitation voltage value and the second cell excitation current value of the battery module.

8. A battery management system, characterized in that, The battery management system includes the electrochemical impedance measurement circuit according to any one of claims 1-7.

9. A battery pack, characterized in that, The battery pack includes a battery module, an external power supply, and an electrochemical impedance measurement circuit according to any one of claims 1-7. The sampling circuit is electrically connected to the battery module and the controller, the controller is electrically connected to the excitation circuit and the battery module, and the excitation circuit is electrically connected to the external power supply.

10. An electrical appliance, characterized in that, The electrical equipment includes the battery pack as described in claim 9.

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