Electrochemical impedance spectroscopy detection device and battery management system

Abstract

The embodiment of the present application provides a kind of electrochemical impedance spectroscopy detection device and battery management system, comprising: waveform generator, the waveform generator is integrated in the battery monitoring chip;Excitation resistance, detection resistance and MOS switch;Wherein, the waveform generator is used to generate pulse waveform;The gate of the MOS switch is used to receive the pulse waveform;The excitation resistance is used to make the battery generate excitation current when the gate of the MOS switch receives the pulse waveform;The detection resistance is used to convert the excitation current into excitation voltage, and the excitation voltage is used to calculate the electrochemical impedance of the battery, and the electrochemical impedance of the battery under different frequencies is used to form the electrochemical impedance spectroscopy of the battery.The electrochemical impedance spectroscopy detection device of the embodiment of the present application can reduce the cost and volume of EIS detection, so that it can be widely applied in BMS.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrochemical impedance spectroscopy detection device and a battery management system. Background Technology

[0002] Existing battery management systems (BMS) for new energy vehicles or energy storage systems primarily monitor battery status by tracking physical parameters such as voltage, temperature, and current. Based on these parameters, they calculate state parameters such as State of Charge (SOC), State of Health (SOH), or Direct Current Resistance (DCR). For example, SOC is calculated based on the ampere-hour integral of the current, supplemented by voltage correction for specific states. However, this method requires a complete charge-discharge cycle to learn and determine the maximum battery capacity. Voltage correction typically requires determining the battery's terminal voltage, which is related to factors such as current, temperature, and DC resistance at that time. Therefore, the algorithm is complex, and accuracy cannot be improved.

[0003] Electrochemical impedance spectroscopy (EIS) is a response of an electrochemical system to an external stimulus. It can be used to analyze the internal resistance, double-layer capacitance, and Faraday impedance of a battery. According to relevant research, the impedance spectrum exhibited by a battery under different state parameters is inconsistent. Therefore, battery state monitoring can be performed based on EIS detection.

[0004] Although existing technologies can perform EIS testing on batteries, they suffer from high costs, large size, and complex solutions. They are typically used in workstations for battery research and analysis, and are not suitable for application in battery status detection during use. Summary of the Invention

[0005] This application provides an electrochemical impedance spectroscopy (EIS) detection device and a battery management system, which can reduce the cost and volume of EIS detection, enabling its widespread application in BMS.

[0006] In a first aspect, an electrochemical impedance spectroscopy (EIS) detection device is provided, comprising a waveform generator integrated into a battery monitoring chip; an excitation resistor, a detection resistor, and a MOS switch; one end of the excitation resistor and one end of the detection resistor are connected to the positive terminal of the battery, the other end of the excitation resistor and the detection resistor are connected to the negative terminal of the battery, one end of the other end of the excitation resistor and the other end of the detection resistor are connected to the source of the MOS switch, and the other end of the other end of the excitation resistor and the detection resistor are connected to the drain of the MOS switch; wherein, the waveform generator is used to generate a pulse waveform, the gate of the MOS switch is used to receive the pulse waveform, the excitation resistor is used to cause the battery to generate an excitation current when the gate of the MOS switch receives the pulse waveform, the detection resistor is used to convert the excitation current into an excitation voltage, the excitation voltage is used to calculate the electrochemical impedance of the battery, and the electrochemical impedance of the battery at different frequencies is used to form the electrochemical impedance spectrum of the battery.

[0007] By injecting excitation current through the waveform generator in the battery monitoring chip, the EIS detection device is cleverly integrated into the chip architecture, thereby reducing the cost and size of EIS detection, enabling its widespread application in BMS, and making it easier to apply to state detection during battery use.

[0008] In conjunction with the first aspect, in a first possible implementation of the first aspect, the detection device further includes: an analog-to-digital converter for sampling the excitation voltage corresponding to the battery.

[0009] By using an analog-to-digital converter to convert analog signals into digital signals that can be processed by a processor, it is possible to quantify the electrochemical impedance of a battery.

[0010] In conjunction with some implementations of the first aspect described above, in a second possible implementation of the first aspect, each of the plurality of analog-to-digital converters is used to sample the excitation voltage corresponding to the corresponding battery in the plurality of batteries, wherein the plurality of analog-to-digital converters correspond one-to-one with the plurality of batteries.

[0011] By employing multiple analog-to-digital converters, the excitation voltages corresponding to multiple batteries can be obtained simultaneously, and the electrochemical impedance spectra of multiple batteries can be further obtained, thereby improving the detection efficiency.

[0012] In conjunction with some implementations of the first aspect described above, in a third possible implementation of the first aspect, the analog-to-digital converter is used to sample multiple excitation voltages that correspond one-to-one with the multiple batteries.

[0013] In combination with some of the implementations of the first aspect, in the fourth possible implementation of the first aspect, the multiple excitation voltages are sampled by the analog-to-digital converter through a multiplexer that switches between channels.

[0014] By employing a common analog-to-digital converter and using a multiplexer to sample the excitation voltages of multiple batteries in different time periods to obtain the electrochemical impedance spectra of these batteries, the circuit structure can be simplified, further reducing the cost of EIS detection.

[0015] In combination with some of the implementations of the first aspect, in the fifth possible implementation of the first aspect, the analog-to-digital converter reuses the analog-to-digital converter in the battery monitoring chip.

[0016] Reusing the analog-to-digital converter in the battery monitoring chip can further reduce the cost and size of EIS testing.

[0017] In combination with some of the implementations of the first aspect, in the sixth possible implementation of the first aspect, the excitation voltage and the actual voltage of the battery during use are sampled by the analog-to-digital converter through a multiplexer in the battery monitoring chip.

[0018] Similarly, by using a common analog-to-digital converter and sampling the excitation voltage of the battery and the actual voltage of the battery during use in time periods through a multiplexer, the circuit structure can be simplified and the cost of EIS detection can be further reduced.

[0019] In combination with some of the implementations of the first aspect, in the seventh possible implementation of the first aspect, the MOS switch is integrated into the battery monitoring chip.

[0020] Integrating the MOS switch into the battery monitoring chip facilitates the diagnosis of the MOS switch.

[0021] In combination with some of the implementations of the first aspect described above, in the eighth possible implementation of the first aspect, the MOS switch is located outside the battery monitoring chip.

[0022] Placing the MOS switch outside the battery monitoring chip allows for flexible MOS switch design and facilitates adjustment of the excitation current generated by the battery.

[0023] In conjunction with some implementations of the first aspect described above, in the ninth possible implementation of the first aspect, the battery is a battery pack formed by multiple individual cells connected in series; the excitation resistor is used to cause the battery pack to generate an excitation current when the gate of the MOS switch receives the pulse waveform; the detection resistor is used to convert the excitation current into an excitation voltage, the excitation voltage is used to calculate the electrochemical impedance of the battery pack, and the electrochemical impedance of the battery pack at different frequencies is used to form the electrochemical impedance spectrum of the battery pack.

[0024] In practical applications, not every single cell needs to be tested by EIS. Using a single EIS detection channel to measure the electrochemical impedance of a battery pack composed of multiple cells can reduce the number of pins on the battery monitoring chip.

[0025] In combination with some of the implementations of the first aspect described above, in the tenth possible implementation of the first aspect, the electrochemical impedance spectroscopy is calculated and obtained by the data processing unit in the battery monitoring chip.

[0026] In conjunction with some implementations of the first aspect described above, in the eleventh possible implementation of the first aspect, the excitation voltage after the analog-to-digital converter is filtered by the data filtering unit in the battery monitoring chip.

[0027] Filtering the digital signal after it has been converted by an analog-to-digital converter can increase the stability of the sampled values.

[0028] In conjunction with some implementations of the first aspect described above, in the twelfth possible implementation of the first aspect, the excitation resistor and the detection resistor are also used to perform discharge equalization of the battery when the MOS switch is turned on.

[0029] In conjunction with some implementations of the first aspect described above, in the thirteenth possible implementation of the first aspect, the electrochemical impedance spectroscopy of the battery is used to obtain the state parameters of the battery, which include at least one of the following: state of charge (SOC), state of health (SOH), and DC impedance (DCR).

[0030] EIS (Electronic Information System) has high sensitivity and good real-time performance in detecting battery state parameters. It can identify and warn of minute material changes inside the battery before they are reflected in the battery's voltage and temperature, thus providing more accurate and timely warnings of thermal runaway.

[0031] In a second aspect, a battery management system is provided, including an electrochemical impedance spectroscopy detection device and a battery monitoring chip as described in the first aspect and any possible implementation of the first aspect. A waveform generator is integrated in the battery monitoring chip. The detection device is used to output the excitation voltage. The battery monitoring chip is used to calculate the electrochemical impedance of the battery based on the excitation voltage. The electrochemical impedance of the battery at different frequencies is used to form the electrochemical impedance spectrum of the battery.

[0032] In conjunction with the second aspect, in the first possible implementation of the second aspect, the MOS switch is integrated into the battery monitoring chip.

[0033] In combination with some implementations of the second aspect described above, in a second possible implementation of the second aspect, the MOS switch is located outside the battery monitoring chip. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0035] Figure 1 This is a schematic block diagram of the electrochemical impedance spectroscopy detection device disclosed in the embodiments of this application.

[0036] Figure 2 This is a schematic block diagram of a single-cell-single EIS detection channel detection device disclosed in an embodiment of this application.

[0037] Figure 3 This is another schematic block diagram of the single-cell-single EIS detection channel detection device disclosed in the embodiments of this application.

[0038] Figure 4 This is another schematic block diagram of the detection device for a single cell-single EIS detection channel disclosed in the embodiments of this application.

[0039] Figure 5 This is a schematic block diagram of a multi-cell, multi-EIS detection channel detection device disclosed in an embodiment of this application.

[0040] Figure 6 This is another schematic block diagram of the multi-cell, multi-EIS detection channel detection device disclosed in the embodiments of this application.

[0041] Figure 7 This is another schematic block diagram of the multi-cell, multi-EIS detection channel detection device disclosed in the embodiments of this application.

[0042] Figure 8 This is a schematic block diagram of the detection device for multi-cell single EIS detection channel disclosed in the embodiments of this application.

[0043] Figure 9 This is a schematic block diagram of the battery management system disclosed in the embodiments of this application. Detailed Implementation

[0044] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0045] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing 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, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0046] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0047] Electrochemical impedance spectroscopy (EIS) involves applying a perturbation signal to an electrochemical system and then observing the system's response to analyze its electrochemical properties. Unlike DC potential or current, EIS applies a small-amplitude AC sinusoidal potential wave with varying frequencies. The measured response signal is not a change in DC current or potential over time, but rather the ratio of AC potential to current, commonly referred to as the system's impedance, which varies with the sinusoidal wave frequency ω, or the phase angle of the impedance with frequency.

[0048] For example, when a disturbance signal X is input into an electrochemical system M, it will output a response signal Y. The function used to describe the relationship between the disturbance and the response is called the transfer function G(ω). That is: G(ω) = Y / X. If X is a sinusoidal current signal with an angular frequency of ω, then Y is a sinusoidal potential signal with an angular frequency of ω. In this case, the transfer function G(ω) is also a function of frequency, called the frequency response function. This frequency response function is called the impedance of system M, denoted by Z. EIS technology measures different frequencies. The ratio of the disturbance signal X to the response signal Y is used to obtain the real part Z', imaginary part Z”, magnitude |Z|, and phase angle of the impedance at different frequencies. These quantities are then plotted as curves in various forms to obtain electrochemical impedance spectroscopy.

[0049] An electrochemical system can be viewed as an equivalent circuit, composed of basic components such as resistors (R), capacitors (C), and inductors (L) connected in series or parallel. Electrochemical inductance analysis (EIS) can determine the composition of this equivalent circuit and the values ​​of each component. By utilizing the electrochemical meaning of these components, the structure of the electrochemical system and the nature of its polarization processes can be analyzed. For example, it can analyze the battery's internal resistance (including the resistance of the electrolyte and electrodes), double-layer capacitance, and Faraday impedance (including charge transfer resistance and Warburg impedance).

[0050] According to relevant research, the electrochemical impedance spectroscopy (EIS) of batteries varies under different state of charge (SOC), state of harmonics (SOH), and direct current retrieval (DCR). Therefore, EIS can be used to detect the state of the battery.

[0051] Current EIS testing of batteries primarily involves directly inputting different frequencies of excitation into the battery using an external DC-DC converter, then acquiring the corresponding responses to calculate the battery's electrochemical impedance spectroscopy (EIS). While existing technologies can perform EIS testing on batteries, the need for an additional DC-DC converter makes these EIS testing devices costly, bulky, and complex. They are mainly used in workstations for battery research and analysis, and not for state monitoring during battery use.

[0052] In view of this, embodiments of this application provide a novel electrochemical impedance spectroscopy detection device, which cleverly injects excitation current through a waveform generator in a battery monitoring chip, thereby achieving...

[0053] The EIS detection device is integrated into the chip architecture, which reduces the cost and size of EIS detection, enabling its widespread application in BMS and making it easier to apply for state detection during battery use.

[0054] It should be understood that the battery in the embodiments of this application can be a lithium-ion battery, lithium metal battery, lead-acid battery, nickel-metal hydride battery, lithium-sulfur battery, lithium-air battery, or sodium-ion battery, etc., and is not limited thereto. In terms of scale, the battery in the embodiments of this application can be a single cell, or a battery module or battery pack including multiple cells, or it can also be called a battery pack, and is not limited thereto. In terms of application scenarios, the battery can be used in power devices such as automobiles and ships. For example, it can be used in electric vehicles to power the motor of the electric vehicle, serving as the power source for electric vehicles. The battery can also power other electrical components in electric vehicles, such as the in-vehicle air conditioner and in-vehicle media player.

[0055] Figure 1 A schematic block diagram of an electrochemical impedance spectroscopy detection device 100 according to an embodiment of this application is shown.

[0056] like Figure 1 As shown, the detection device 100 includes: a waveform generator 110 integrated in the battery monitoring chip 200; an excitation resistor 120, a detection resistor 130, and a MOS switch 140. One end of the excitation resistor 120 and one end of the detection resistor 130 are connected to the positive terminal of the battery 300, the other end of the excitation resistor 120 and one end of the detection resistor 130 are connected to the negative terminal of the battery 300, one of the other ends of the excitation resistor 120 and the other end of the detection resistor 130 is connected to the source of the MOS switch 140, and the other end of the other end of the excitation resistor 120 and the other end of the detection resistor 130 is connected to the drain of the MOS switch 140.

[0057] In this circuit, MOS switch 140 is an abbreviation for Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). Waveform generator 110 is used to generate pulse waveforms, i.e., pulse-width modulation (PWM) waveforms, also known as square waves. The gate of MOS switch 140 is used to receive the pulse waveform generated by waveform generator 110. The excitation resistor 120 is used to cause the battery 300 to generate an excitation current when the gate of MOS switch 140 receives the pulse waveform generated by waveform generator 110. The sensing resistor 130 is used to convert the excitation current generated by battery 300 into an excitation voltage, which is used to calculate the electrochemical impedance of battery 300.

[0058] Waveform generator 110 can generate pulse waveforms of different frequencies. Pulse waveforms of different frequencies correspond to different electrochemical impedances of battery 300. Different electrochemical impedances can form the electrochemical impedance spectrum of battery 300.

[0059] Specifically, the waveform generator 110 can generate pulse waveforms within the frequency range of 100mHz to 5kHz to drive the MOS switch 140 to turn on. The battery 300 will then exhibit different responses depending on the frequency change. By acquiring the voltage across the detection resistor 130, the current response can be determined, allowing the calculation of the electrochemical impedance of the battery 300. After completing one cycle of frequency changes from 100mHz to 5kHz, an electrochemical impedance spectrum, also known as an impedance spectrum curve, can be plotted. Of course, in practical applications, some interference may exist; therefore, multiple measurements can be performed to optimize the impedance spectrum curve.

[0060] EIS detection measures the response of an electrochemical system to external stimuli of different frequencies. Typically, this stimulus can be either a constant voltage or a constant current. Since lithium-ion batteries have low impedance, constant current stimulation is preferred in this embodiment. The constant current stimulation method applies a current of known frequency to the battery through an excitation resistor, causing the battery to generate an excitation current, and then measures the voltage generated across the sensing resistor.

[0061] Battery monitoring chips, also known as battery monitoring chips, battery sampling chips, voltage acquisition chips, cell monitoring chips, or cell sampling chips, are typically used to collect the actual voltage of a battery during use, which is then used by the Battery Management System (BMS) to make various judgments.

[0062] Optionally, the EIS detection device 100 in this embodiment can be applied to a battery management system (BMS), which may include a battery monitoring chip 200.

[0063] Therefore, in this embodiment of the application, by integrating the waveform generator in the EIS detection device into the battery monitoring chip and using simple electronic components such as resistors and MOS switches to apply the excitation to the battery, without the need for additional equipment to inject excitation into the battery, the EIS detection scheme is simplified, the cost of EIS detection is reduced, and EIS detection can be widely used in BMS.

[0064] Optionally, in this embodiment, the electrochemical impedance spectroscopy of the battery 300 is used to obtain the state parameters of the battery 300, which include at least one of SOC, SOH, and DCR. Optionally, the electrochemical impedance spectroscopy of the battery 300 can also be used to evaluate parameters such as internal resistance and internal temperature of the battery 300.

[0065] In one embodiment, the obtained electrochemical impedance spectrum can be compared with the impedance spectrum curve obtained in the testing phase to establish a battery model. The battery model can be the equivalent circuit described above. Based on the battery model, the above-mentioned relevant parameters of battery 300 can be inferred.

[0066] In another embodiment, the aforementioned parameters of battery 300 can be obtained directly from the obtained electrochemical impedance spectroscopy using an algorithm. It should be understood that this application does not limit how the relevant parameters of the battery are obtained based on the electrochemical impedance spectroscopy.

[0067] EIS (Electronic Information System) has high sensitivity and good real-time performance in detecting battery state parameters. It can identify and warn of minute material changes inside the battery before they are reflected in the battery's voltage and temperature, thus providing more accurate and timely warnings of thermal runaway.

[0068] It should be noted that although the waveform generator in the electrochemical impedance spectroscopy detection device provided in this application embodiment is integrated into the battery monitoring chip, optionally, the waveform generator can also be implemented in other ways, for example, by running code in the processor of the BMS to generate pulse waveforms. As long as the waveform generator is implemented using existing chips in the BMS without using additional equipment, it is within the scope of protection of the technical solution of this application.

[0069] Optionally, in this embodiment, the detection device 100 may further include an analog-to-digital converter for sampling the excitation voltage corresponding to the battery 300.

[0070] An analog-to-digital converter (ADC) is a circuit that converts analog signals into digital signals. More specifically, an ADC can convert analog signals that are continuous in time and amplitude into digital signals that are discrete in time and amplitude. In this embodiment, the excitation voltage corresponding to the battery 300 can be sampled by sampling the voltage across the detection resistor 130.

[0071] It's important to note that ADCs can use single-ended input, also known as single-ended sampling, where the ADC has only one input terminal and uses the common ground as the return terminal of the circuit. This input method is simple and easy to implement. ADCs can also use differential input, also known as differential sampling, where the ADC has two input terminals. Since these two input terminals are usually located together, they experience roughly the same level of interference. Input common-mode interference is subtracted when input to the ADC, thus reducing interference.

[0072] For ease of description, a new term will be introduced below: EIS detection channel. An EIS detection channel may include an excitation resistor, a sensing resistor, and a MOS switch. The connection method of the excitation resistor, sensing resistor, and MOS switch can be found in [reference needed]. Figure 1 The description.

[0073] Optionally, in one embodiment of this application, a battery can be considered as a single battery cell. One battery cell corresponds to one EIS detection channel. If EIS detection is required for each of multiple battery cells, then each of the multiple battery cells needs to correspond to one of the multiple EIS detection channels.

[0074] Optionally, in another embodiment of this application, a battery can be considered as multiple individual battery cells. For example, it can be a battery pack formed by connecting multiple individual battery cells in series. In practical applications, not every individual battery cell needs to be EIS detected. Therefore, an EIS detection channel can be used to perform EIS detection on the battery pack. That is, the excitation resistor in the single EIS detection channel is used to generate an excitation current in the battery pack when the gate of the MOS switch in the single EIS detection channel receives a pulse waveform, and the detection resistor in the single EIS detection channel is used to convert the excitation current generated by the battery pack into an excitation voltage. The obtained excitation voltage is used to calculate the electrochemical impedance of the battery pack, and the electrochemical impedance of the battery pack at different frequencies is used to form the electrochemical impedance spectrum of the battery pack.

[0075] In cases where EIS detection is required for each of multiple battery cells, the multiple battery cells are respectively passed through multiple EIS detection channels and sampled by an ADC to obtain multiple excitation voltages.

[0076] Optionally, the detection device 100 includes an ADC, which is used to sample multiple excitation voltages corresponding one-to-one with multiple batteries. Further, the detection device 100 may also include a multiplexer, through which the ADC samples the multiple excitation voltages in separate channels.

[0077] Optionally, the detection device 100 may also include multiple ADCs, i.e., one ADC corresponds to one EIS detection channel, and each of the multiple ADCs is used to sample the excitation voltage of the corresponding battery in the multiple batteries.

[0078] It should be understood that multiple individual cells can be divided into two parts. Each individual cell in one part needs to be tested by EIS, that is, each individual cell in this part corresponds to an EIS testing channel; the other part of the individual cells is tested as a battery pack, that is, the battery pack corresponds to an EIS testing channel.

[0079] Optionally, in this embodiment, the ADC in the detection device 100 can reuse the ADC in the battery monitoring chip. The ADC in the battery monitoring chip is typically used to acquire the actual voltage of the battery during use. That is, the ADC used to acquire the excitation voltage of the battery can reuse the ADC used to acquire the actual voltage of the battery during use. Similarly, the ADC in the battery monitoring chip samples the excitation voltage and the actual voltage of the battery during use through a multiplexer.

[0080] Optionally, in this embodiment, the ADC in the detection device 100 may not reuse the ADC in the battery monitoring chip, but may be integrated into the battery monitoring chip. That is, the ADC used to acquire the excitation voltage and the ADC used to acquire the actual voltage of the battery during use are both integrated into the battery monitoring chip and are independent of each other.

[0081] In summary, if there are multiple excitation voltages and multiple actual voltages, this can be achieved in the following ways:

[0082] Firstly, the battery monitoring chip may consist of only one ADC, which must acquire both the multiple excitation voltages and the multiple actual voltages. Furthermore, this single ADC acquires the multiple excitation voltages and the multiple actual voltages through a multiplexer within the battery monitoring chip, using multiple channels.

[0083] Secondly, the battery monitoring chip includes multiple ADCs, which are divided into two parts. Each ADC in one part is used to acquire the corresponding excitation voltage from the multiple excitation voltages. Each ADC in the other part is used to acquire the corresponding actual voltage from the multiple actual voltages. In other words, each of the multiple ADCs corresponds one-to-one with each of the multiple excitation voltages and the multiple actual voltages. In this implementation, a multiplexer is not required.

[0084] Third, the battery monitoring chip includes two ADCs: one ADC for acquiring the multiple excitation voltages and the other ADC for acquiring the multiple actual voltages. Similarly, the battery monitoring chip may include two multiplexers: one multiplexer for switching multiple excitation voltages to the corresponding ADCs for sampling via separate channels, and the other multiplexer for switching multiple actual voltages to the corresponding ADCs for sampling via separate channels.

[0085] Fourth, the battery monitoring chip includes multiple ADCs, wherein each of the multiple ADCs acquires one of the multiple excitation voltages and one of the multiple actual voltages. Similarly, the battery monitoring chip may include multiple multiplexers, and each of the multiple ADCs acquires a corresponding excitation voltage or a corresponding actual voltage through a corresponding multiplexer.

[0086] Fifth, the battery monitoring chip includes multiple ADCs, which can be divided into at least three of the following five categories: ADC that collects only one excitation voltage, ADC that collects only one actual voltage, ADC that collects multiple excitation voltages, ADC that collects multiple actual voltages, and ADC that collects both excitation voltage and actual voltage.

[0087] It should be understood that the ADC used to acquire the excitation voltage may not be integrated into the battery monitoring chip, but rather a separate ADC chip may be used.

[0088] In one embodiment, the MOS switch 140 in the detection device 100 can be integrated into the battery monitoring chip, which is beneficial for the diagnosis of the MOS switch.

[0089] In another embodiment, the MOS switch 140 in the detection device 100 can also be disposed outside the battery monitoring chip. In this scheme, the MOS switch is flexible and facilitates adjustment of the excitation current generated by the battery.

[0090] Optionally, in the embodiments of this application, the excitation voltage obtained by the ADC sampling can be converted into an electrochemical impedance spectrum by the data processing unit in the battery monitoring chip.

[0091] Optionally, in this embodiment, the excitation voltage sampled by the ADC can also be filtered by the data filtering unit in the battery monitoring chip, thereby increasing the stability of the sampled values ​​and improving the detection reliability of the detection device 100.

[0092] Optionally, in this embodiment, the excitation resistor 120 and the detection resistor 130 can also perform discharge equalization on the battery 300 when the MOS switch 140 is turned on. At this time, the gate of the MOS switch 140 receives a constant level. The level of this constant level can depend on the type of MOS switch 140.

[0093] It should be noted that the above modules may not reuse the functional modules in the battery monitoring chip. For example, the data processing unit can be implemented using the processor in the BMS.

[0094] The following will combine Figures 2 to 8The electrochemical impedance spectroscopy detection device of the present application embodiment is described in detail. The detection device adds EIS detection function to the existing battery monitoring chip. For other functions of the battery monitoring chip, please refer to the battery monitoring chips currently on the market.

[0095] For ease of description, the various modules involved in the embodiments of this application will be introduced one by one below.

[0096] A waveform generator 410 is used to generate pulse waveforms, which then drive a MOS switch 440 to turn on the MOS switch at a specified frequency. This waveform generator 410 can be integrated into the battery monitoring chip 500.

[0097] The excitation resistor 420 is used to generate an excitation current for the battery 600 when the MOS switch 440 is turned on. The appropriate value of the excitation resistor can be selected according to the actual required excitation current.

[0098] The sensing resistor 430 is used to detect the excitation current. Specifically, the excitation current can be converted into an excitation voltage through the sensing resistor 430, and then sampled by the ADC 505. It should be noted that the sensing resistor 430 can have two sampling lines, S_P and S_N, to achieve differential sampling, thereby improving noise immunity. However, S_N is optional.

[0099] The MOS switch 440 is used to control the generation of excitation current; it generates excitation current when turned on and stops generating excitation current when turned off. Specifically, the gate of the MOS switch 440 can receive a pulse waveform generated by the waveform generator 410, and the MOS switch 440 is turned on and off under the control of this pulse waveform. The MOS switch 440 can be integrated into the battery monitoring chip 500, such as... Figure 2 As shown; the MOS switch 440 can be located outside the battery monitoring chip 500, such as... Figures 3 to 8 As shown.

[0100] The ADC 505 is used to acquire the input voltage of the cell voltage input channel, that is, the actual voltage of the battery 600 during use; the ADC 505 is also used to acquire the voltage across the sensing resistor 430, that is, the excitation voltage. Specifically, the ADC 505 converts the input analog voltage signal into a digital signal.

[0101] The multiplexer 510 switches the input voltage (including excitation voltage and / or actual voltage) to the ADC505 for sampling via separate channels.

[0102] The data filtering unit 515 is used to filter the digital signal converted by the ADC 505, increase the stability of sampling, and thus improve the reliability of detection.

[0103] The data processing unit 520 processes the excitation voltage and actual voltage converted by the ADC 505, and converts the acquired excitation voltage into an electrochemical impedance spectroscopy spectrum. This data processing unit 520 can execute instructions transmitted from the communication unit 535 to control the operation of the battery monitoring chip 500.

[0104] Data storage unit 525 is used to store the collected voltage data.

[0105] The power supply unit 530 is used to convert the changing cell voltage into a stable voltage for powering other internal modules, such as providing a reference power supply for the ADC 505 or a power supply for the communication unit 535.

[0106] The communication unit 535 serves as the transmitting and receiving interface for the battery monitoring chip 500, used to receive externally transmitted commands or transmit internal data from the battery monitoring chip 500 to the outside.

[0107] The temperature protection unit 540 is used to detect the temperature of the battery monitoring chip 500. When the temperature exceeds a certain threshold, it disables the MOS switch 440 to reduce chip power consumption and prevent chip overheating and burning or causing instability in other modules.

[0108] The General-Purpose Input / Output (GPIO) control unit 545 is used to control the GPIO interface of the battery monitoring chip, expanding the chip's functionality. This GPIO can be multiplexed as a Serial Peripheral Interface (SPI), an Inter-Integrated Circuit (IIC) bus, or an analog signal sampling interface.

[0109] Additionally, Vss can be understood as the power ground of the battery monitoring chip.

[0110] from Figures 1 to 8 As can be seen, one end of the excitation resistor is connected to the positive terminal of the battery, while one end of the sensing resistor is connected to the negative terminal of the battery. It should be noted that this connection is merely an example; obviously, their positions can be interchanged. That is, one end of the excitation resistor can be connected to the negative terminal of the battery, and one end of the sensing resistor can be connected to the positive terminal of the battery. Similarly, the connection relationships between the excitation resistor and the sensing resistor and the MOS switch can also be interchanged; this embodiment is not intended to limit the scope of the application.

[0111] Figure 2 A schematic block diagram of a detection device with a single cell and a single EIS detection channel is shown. Figure 2As shown, the detection device includes an EIS detection channel 400 and a waveform generator 410. The EIS detection channel 400 includes an excitation resistor 420, a detection resistor 430, and a MOS switch 440, used for EIS detection of the battery 600. The detection resistor 430 has two sampling lines, S_P and S_N, at its two ends. The battery 600 can be a single cell, and the MOS switch 440 is integrated into the battery monitoring chip 500.

[0112] Specifically, the gate of the MOS switch 440 receives the pulse waveform generated by the waveform generator 410; when the gate of the MOS switch 440 receives the pulse waveform, the excitation resistor 420 causes the battery cell 600 to generate an excitation current; the detection resistor 430 converts the excitation current into an excitation voltage; the ADC 505 acquires the excitation voltage, and the data processing unit 520 processes the acquired excitation voltage to obtain the electrochemical impedance of the battery 600. Multiple electrochemical impedances of the battery 600 obtained at multiple frequencies can form the electrochemical impedance spectrum of the battery 600.

[0113] like Figure 2 As shown, the ADC 505 is also used to acquire the actual voltage. The battery 600 also has two sampling lines, VC0 and VC1, at its two ends. The excitation voltage and the actual voltage are switched to the ADC 505 for sampling via a multiplexer 510.

[0114] Figure 3 Another schematic block diagram of a single-cell, single-EIS detection channel detection device is shown. (Compared to...) Figure 2 In contrast, the MOS switch 440 is located externally to the battery monitoring chip 500. The functions of other modules can be found in [reference needed]. Figure 2 The description.

[0115] Figure 4 Another schematic block diagram of a single-cell, single-EIS detection channel detection device is shown. (Compared to...) Figure 3 In contrast, the ADC used to acquire the excitation voltage and the ADC used to acquire the actual voltage are set up independently. That is, ADC 505 includes ADC 505a and ADC 505b. Since both the excitation voltage and the actual voltage are sampled by their respective ADCs, a multiplexer is not required. For the functions of other modules, please refer to [link to documentation]. Figure 2 The description.

[0116] Figure 5 A schematic block diagram of a multi-cell, multi-EIS detection channel detection device is shown. Figure 3In contrast, this detection device includes multiple EIS detection channels (400_1, 400_2, ..., 400_n) and a waveform generator 410 for EIS detection of multiple individual battery cells (600_1, 600_2, ..., 600_n). Each EIS detection channel includes an excitation resistor, a detection resistor, and a MOS switch. For example, EIS detection channel 400_1 includes an excitation resistor 420_1, a detection resistor 430_1, and a MOS switch 440_1; EIS detection channel 400_2 includes an excitation resistor 420_2, a detection resistor 430_2, and a MOS switch 440_2; ...; EIS detection channel 400_n includes an excitation resistor 420_n, a detection resistor 430_n, and a MOS switch 440_n. Each EIS detection channel (400_1, 400_2, ..., 400_n) has sampling lines (S_P1, S_P2, ..., S_Pn) and sampling lines (S_N1, S_N2, ..., S_Nn) at both ends of the detection resistor (430_1, 430_2, ..., 430_n). Similarly, each individual cell (600_1, 600_2, ..., 600_n) has sampling lines (VC0, VC1, ..., VCn-1, VCn) at both ends. The ADC505 samples not only the excitation voltages of multiple individual battery cells (600_1, 600_2, ..., 600_n), but also the actual voltages of these cells. These excitation and actual voltages are switched between channels by a multiplexer 510 and fed to the ADC505 for sampling. The functions of other modules can be found in [link to other modules]. Figure 2 The description.

[0117] Figure 6 Another schematic block diagram of a multi-cell, multi-EIS detection channel detection device is shown. (Compared to...) Figure 5 In contrast, the ADC505 includes multiple ADCs, divided into two categories: ADC 505a and ADC 505b. One category of ADCs is used to acquire excitation voltages, and the other category is used to acquire actual voltages. The number of ADCs in each category is the same as the number of corresponding voltages to be acquired. For example, ADC 505a_1, ADC 505a_2, ..., ADC 505a_n-1, ADC 505a_n are used to acquire n excitation voltages, and ADC 505b_1, ADC 505b_2, ..., ADC 505b_n-1, ADC 505b_n are used to acquire n actual voltages. Since the number of voltages to be acquired is the same as the number of ADCs, no multiplexer is needed. For the functions of other modules, please refer to [link to documentation]. Figure 2 The description.

[0118] Figure 7 Another schematic block diagram of a multi-cell, multi-EIS detection channel detection device is shown. (Compared to...) Figure 5 In comparison, the ADC 505 includes two ADCs, ADC 505a and ADC 505b. One ADC is used to acquire multiple excitation voltages, and the other ADC is used to acquire multiple actual voltages. Similarly, the multiplexer 510 includes two multiplexers, multiplexer 510a and multiplexer 510b. One multiplexer is used to switch multiple excitation voltages to the corresponding ADC for sampling via separate channels, and the other multiplexer is used to switch multiple actual voltages to the corresponding ADC for sampling via separate channels. The functions of other modules can be found in [link to documentation]. Figure 2 The description.

[0119] Figure 8 A schematic block diagram of a multi-cell, single EIS detection channel detection device is shown. Figure 5 In contrast, the single EIS detection channel 400 is used to perform EIS detection on a battery pack composed of multiple individual cells (600_1, 600_2, ..., 600_n) to obtain the corresponding excitation voltage of the battery pack. The ADC 505 is used not only to acquire the actual voltage of each individual cell (600_1, 600_2, ..., 600_n), but also to acquire the corresponding excitation voltage of the battery pack. The multiplexer 510 is used to switch the actual voltages of the multiple individual cells and the excitation voltage of the battery pack to the ADC 505 for sampling via separate channels. It should be noted that... Figure 8 In the illustrated embodiment, (n+1) ADCs can also be set, where n ADCs are used to acquire n actual voltages, and 1 ADC is used to acquire one excitation voltage corresponding to the battery pack. The functions of other modules can be found in [reference needed]. Figure 2 The description.

[0120] It should be noted that, Figures 3 to 8 Each of the embodiments in can be as follows Figure 2 As shown, the MOS switch 440 is integrated into the battery monitoring chip 500.

[0121] like Figure 9As shown in the embodiments of this application, a battery management system 900 is also provided. The battery management system 900 includes an electrochemical impedance spectroscopy detection device 910 and a battery monitoring chip 920. The detection device 910 can be the electrochemical impedance spectroscopy detection device described in the various embodiments above. The waveform generator in the detection device 910 is integrated into the battery monitoring chip 920. The detection device 910 is used to output an excitation voltage. The battery monitoring chip 920 is used to calculate the electrochemical impedance of the battery based on the excitation voltage output by the detection device 910. The electrochemical impedance obtained at different frequencies is used to form the electrochemical impedance spectrum of the battery.

[0122] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. 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. A detection device for electrochemical impedance spectroscopy, characterized in that, include: A waveform generator, which is integrated into a battery monitoring chip; An excitation resistor, a detection resistor, and a MOS switch are provided, wherein the excitation resistor is connected between the positive terminal of the battery and the drain of the MOS switch, and the detection resistor is connected between the negative terminal of the battery and the source of the MOS switch. The waveform generator is used to generate a pulse waveform, the gate of the MOS switch is used to receive the pulse waveform, the excitation resistor is used to cause the battery to generate an excitation current when the gate of the MOS switch receives the pulse waveform, the detection resistor is used to convert the excitation current into an excitation voltage, the excitation voltage is used to calculate the electrochemical impedance of the battery, and the electrochemical impedance of the battery at different frequencies is used to form the electrochemical impedance spectrum of the battery. The excitation resistor and the detection resistor are also used to perform discharge equalization of the battery when the MOS switch is turned on.

2. The detection device according to claim 1, characterized in that, The detection device further includes: An analog-to-digital converter is used to sample the excitation voltage corresponding to the battery.

3. The detection device according to claim 2, characterized in that, Each of the plurality of analog-to-digital converters is used to sample the excitation voltage corresponding to the corresponding battery in the plurality of batteries, wherein the plurality of analog-to-digital converters correspond one-to-one with the plurality of batteries.

4. The detection device according to claim 2, characterized in that, The analog-to-digital converter is used to sample multiple excitation voltages that correspond one-to-one with the multiple batteries.

5. The detection device according to claim 4, characterized in that, The multiple excitation voltages are switched to the analog-to-digital converter for sampling via a multiplexer.

6. The detection device according to claim 2, characterized in that, The analog-to-digital converter reuses the analog-to-digital converter in the battery monitoring chip.

7. The detection device according to claim 6, characterized in that, The excitation voltage and the actual voltage of the battery during use are sampled by the analog-to-digital converter through a multiplexer in the battery monitoring chip.

8. The detection device according to any one of claims 1 to 7, characterized in that, The MOS switch is integrated into the battery monitoring chip.

9. The detection device according to any one of claims 1 to 7, characterized in that, The MOS switch is located outside the battery monitoring chip.

10. The detection device according to any one of claims 1 to 7, characterized in that, The battery is a battery pack formed by connecting multiple individual battery cells in series. The excitation resistor is used to cause the battery pack to generate an excitation current when the gate of the MOS switch receives the pulse waveform; The detection resistor is used to convert the excitation current into an excitation voltage, and the excitation voltage is used to calculate the electrochemical impedance of the battery pack. The electrochemical impedance of the battery pack at different frequencies is used to form the electrochemical impedance spectrum of the battery pack.

11. The detection device according to any one of claims 1 to 7, characterized in that, The electrochemical impedance spectroscopy is calculated by the data processing unit in the battery monitoring chip.

12. The detection device according to any one of claims 1 to 7, characterized in that, The excitation voltage after passing through the analog-to-digital converter is filtered by the data filtering unit in the battery monitoring chip.

13. The detection device according to any one of claims 1 to 7, characterized in that, The electrochemical impedance spectroscopy of the battery is used to obtain the state parameters of the battery, which include at least one of the following: state of charge (SOC), state of health (SOH), and DC impedance (DCR).

14. A battery management system, characterized in that, The device includes an electrochemical impedance spectroscopy detection device and a battery monitoring chip as described in any one of claims 1 to 13, wherein a waveform generator in the detection device is integrated into the battery monitoring chip, the detection device is used to output the excitation voltage, and the battery monitoring chip is used to calculate the electrochemical impedance of the battery based on the excitation voltage, and the electrochemical impedance of the battery at different frequencies is used to form the electrochemical impedance spectrum of the battery.

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