Electrochemical impedance spectrum acquisition method and device based on energy storage battery

Abstract

The invention relates to the technical field of electrochemical impedance spectrum testing, in particular to an electrochemical impedance spectrum obtaining method and device based on an energy storage battery, a microprocessor system, a computer readable storage medium and a computer program product. The method comprises the following steps: sampling to obtain a direct-current bus side voltage, and performing direct-current voltage conversion on the direct-current bus side voltage; carrying out single-pole frequency multiplication modulation on the direct current bus side voltage after the direct current voltage conversion to obtain sine voltage disturbance signals under different frequencies; inputting the sinusoidal voltage disturbance signals under different frequencies into the energy storage battery, and sampling to obtain a current response signal of the energy storage battery; according to the sinusoidal voltage disturbance signal and the current response signal, battery impedance under different frequencies is calculated; and acquiring an electrochemical impedance spectrum of the energy storage battery pack according to the battery impedance under different frequencies. By adopting the method, wide-range, low-cost and high-efficiency online electrochemical impedance spectroscopy detection can be realized.

Description

Technical Field

[0001] The present application relates to the technical field of electrochemical impedance spectroscopy testing, and particularly to a method, device, microprocessor system, computer-readable storage medium, and computer program product for obtaining an electrochemical impedance spectrum based on an energy storage battery. Background Art

[0002] In the fields of new energy power generation and power grid peak shaving and frequency modulation, the health state of energy storage batteries is crucial for the performance and safety of equipment. Accurate assessment and prediction of battery health are the prerequisites for building a battery state monitoring and health management system. As the core component of an energy storage system, the establishment of a digital twin model for a lithium battery pack requires accurate characteristic parameters such as voltage, SOC, temperature, etc. These parameters can be obtained in real time through sensors, but it is difficult to measure the internal electrochemical impedance spectrum of the battery by conventional means.

[0003] Currently, the methods for obtaining impedance information are mainly divided into two categories: non-intrusive and intrusive. Non-intrusive detection techniques include the bridge method, resonance method, and network analyzer method, etc. The principle of the bridge method is simple, but the operation is cumbersome, the hardware connection is complex, and the detection range is limited; although the resonance method is easy to understand, it takes a long time to find the resonance point, has high requirements for the power supply and detection system, and the applicable scenarios are limited; the network analyzer method has strict requirements for measurement conditions, the equipment is complex and the cost is high, making it difficult to promote and use. Intrusive detection techniques measure impedance by introducing a perturbation signal, including the switching methods of passive and active devices, and the method of generating a perturbation source through a specific module. However, these methods cannot precisely control the magnitude and energy distribution of harmonics, making it difficult to expand the application range, and there are problems such as high cost of test equipment, strict requirements for the test environment, and long test time in the off-line detection method.

[0004] Traditional electrochemical impedance spectroscopy detection is usually completed in a laboratory electrochemical workstation, which only supports off-line detection, has a long test time, high cost, and strict requirements for the test environment. Therefore, how to achieve wide-range, low-cost, and high-efficiency on-line electrochemical impedance spectroscopy detection has become an urgent technical problem to be solved. Summary of the Invention

[0005] Based on this, in view of the above technical problems, it is necessary to provide a method, device, microprocessor system, computer-readable storage medium, and computer program product for obtaining an electrochemical impedance spectrum based on an energy storage battery, which can achieve wide-range, low-cost, and high-efficiency on-line electrochemical impedance spectroscopy detection.

[0006] In a first aspect, the present application provides a method for obtaining an electrochemical impedance spectrum based on an energy storage battery, including:

[0007] Sampling the DC bus voltage and performing DC voltage conversion on the DC bus voltage;

[0008] Perform single - pole frequency - doubling modulation on the DC bus - side voltage after DC voltage conversion to obtain sinusoidal voltage disturbance signals at different frequencies;

[0009] Input the sinusoidal voltage disturbance signals at different frequencies into the energy - storage battery, and sample to obtain the current response signal of the energy - storage battery;

[0010] Calculate the battery impedance at different frequencies according to the sinusoidal voltage disturbance signal and the current response signal;

[0011] Obtain the electrochemical impedance spectrum of the energy - storage battery pack according to the battery impedance at different frequencies.

[0012] In one embodiment, the DC voltage conversion of the DC bus - side voltage includes:

[0013] Adopt an LLC resonant conversion circuit to perform DC voltage conversion on the DC bus - side voltage;

[0014] The single - pole frequency - doubling modulation of the DC bus - side voltage after DC voltage conversion includes:

[0015] Adopt an H - bridge inverter circuit to perform single - pole frequency - doubling modulation on the DC bus - side voltage after DC voltage conversion;

[0016] Among them, the voltage output end of the LLC resonant conversion circuit is connected to the DC voltage input end of the H - bridge inverter circuit.

[0017] In one embodiment, the adoption of the H - bridge inverter circuit to perform single - pole frequency - doubling modulation on the DC bus - side voltage after DC voltage conversion includes:

[0018] Adopt an H - bridge inverter circuit, use a bipolar triangular carrier wave and two modulation waves with opposite polarities to perform single - pole frequency - doubling modulation on the DC bus - side voltage after DC voltage conversion, obtain the PWM signal of the switching tube at the corresponding frequency, and further obtain the sinusoidal voltage disturbance signals at different frequencies.

[0019] In one embodiment, the sampling to obtain the DC bus - side voltage includes:

[0020] Sample the DC bus - side voltage through a neutral - point - clamped circuit adopting a T - type connection method.

[0021] In a second aspect, the present application also provides an apparatus for obtaining the electrochemical impedance spectrum based on an energy - storage battery. The apparatus includes a main - circuit module, an impedance detection module, a calculation module, and an impedance - spectrum acquisition module;

[0022] The impedance detection module is used to sample the DC bus - side voltage through the main - circuit module and perform DC voltage conversion on the DC bus - side voltage;

[0023] The impedance detection module is used to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion to obtain sinusoidal voltage disturbance signals at different frequencies;

[0024] The impedance detection module is further used to input the sinusoidal voltage disturbance signals at different frequencies into the energy storage battery, and sample to obtain the voltage response signal and current response signal of the energy storage battery;

[0025] The calculation module is used to calculate the battery impedance at different frequencies according to the voltage response signal and the current response signal;

[0026] The impedance spectrum acquisition module is used to obtain the electrochemical impedance spectrum of the energy storage battery pack according to the battery impedance at different frequencies.

[0027] In one embodiment, the impedance detection module includes an LLC resonant conversion circuit and an H-bridge inverter circuit;

[0028] The LLC resonant conversion circuit is used to sample the DC bus voltage through the main circuit module and perform DC voltage conversion on the DC bus voltage;

[0029] The H-bridge inverter circuit is used to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion to obtain sinusoidal voltage disturbance signals at different frequencies;

[0030] Wherein, the voltage output end of the LLC resonant conversion circuit is connected to the DC voltage input end of the H-bridge inverter circuit.

[0031] In one embodiment, the H-bridge inverter circuit is specifically used to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion by using a bipolar triangular carrier wave and two modulation waves with opposite polarities, obtain the PWM signal of the switching tube at the corresponding frequency, and further obtain sinusoidal voltage disturbance signals at different frequencies.

[0032] In one embodiment, the H-bridge inverter circuit includes a DC bus capacitor, an output inductor, an output capacitor, and four enhanced Nmos transistors; wherein, a freewheeling diode is connected in parallel with each enhanced Nmos transistor.

[0033] In a third aspect, the present application further provides a microprocessor system, including a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0034] Sample the DC bus voltage and perform DC voltage conversion on the DC bus voltage;

[0035] Perform single - pole frequency - doubling modulation on the DC bus voltage after DC voltage conversion to obtain sinusoidal voltage disturbance signals at different frequencies;

[0036] Input the sinusoidal voltage disturbance signals at different frequencies into the energy - storage battery, and sample to obtain the current response signal of the energy - storage battery;

[0037] Calculate the battery impedance at different frequencies according to the sinusoidal voltage disturbance signal and the current response signal;

[0038] Obtain the electrochemical impedance spectrum of the energy - storage battery pack according to the battery impedance at different frequencies.

[0039] In a fourth aspect, the present application also provides a computer - readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0040] Sample the DC bus voltage and perform DC voltage conversion on the DC bus voltage;

[0041] Perform single - pole frequency - doubling modulation on the DC bus voltage after DC voltage conversion to obtain sinusoidal voltage disturbance signals at different frequencies;

[0042] Input the sinusoidal voltage disturbance signals at different frequencies into the energy - storage battery, and sample to obtain the current response signal of the energy - storage battery;

[0043] Calculate the battery impedance at different frequencies according to the sinusoidal voltage disturbance signal and the current response signal;

[0044] Obtain the electrochemical impedance spectrum of the energy - storage battery pack according to the battery impedance at different frequencies.

[0045] In a fifth aspect, the present application also provides a computer program product, including a computer program. When the computer program is executed by a processor, the following steps are implemented:

[0046] Sample the DC bus voltage and perform DC voltage conversion on the DC bus voltage;

[0047] Perform single - pole frequency - doubling modulation on the DC bus voltage after DC voltage conversion to obtain sinusoidal voltage disturbance signals at different frequencies;

[0048] Input the sinusoidal voltage disturbance signals at different frequencies into the energy - storage battery, and sample to obtain the current response signal of the energy - storage battery;

[0049] Calculate the battery impedance at different frequencies according to the sinusoidal voltage disturbance signal and the current response signal;

[0050] Obtain the electrochemical impedance spectrum of the energy - storage battery pack according to the battery impedance at different frequencies.

[0051] The above-mentioned method, device, microprocessor system, computer-readable storage medium, and computer program product for obtaining the electrochemical impedance spectrum of an energy storage battery achieve real-time monitoring of the health status of the energy storage battery by performing impedance spectrum detection during the normal operation of the energy storage system without the need for shutdown or offline operation. This online monitoring method can promptly detect potential problems of the battery and improve the reliability and safety of the energy storage system. Through the single-pole frequency doubling modulation technology, sinusoidal voltage perturbation signals at different frequencies can be generated and injected into the energy storage battery. This method can cover a wide range of frequencies, thereby obtaining more comprehensive battery impedance spectrum information and improving the detection accuracy and resolution. Integrating the impedance detection function into a power electronic converter (such as a PCS) avoids the complex equipment and high costs required for traditional offline detection. At the same time, through fast signal processing and calculation, the acquisition of the impedance spectrum can be efficiently completed, greatly shortening the detection time. Description of the Drawings

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments of the present application or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0053] Figure 1 It is an application environment diagram of the method for obtaining the electrochemical impedance spectrum of an energy storage battery in an embodiment;

[0054] Figure 2 It is a schematic flowchart of the method for obtaining the electrochemical impedance spectrum of an energy storage battery in an embodiment;

[0055] Figure 3 It is a schematic circuit structure diagram of an impedance detection module in an embodiment;

[0056] Figure 4 It is a structural block diagram of the device for obtaining the electrochemical impedance spectrum of an energy storage battery in an embodiment;

[0057] Figure 5 It is a schematic PCS system structure diagram of an impedance detection module in an embodiment;

[0058] Figure 6 It is a schematic diagram of the battery impedance spectrum detection method in an embodiment;

[0059] Figure 7 It is an internal structure diagram of a microprocessor system in an embodiment. Detailed Embodiments

[0060] As energy storage batteries are widely used in many fields such as new energy power generation and power grid peak shaving and frequency modulation, a series of problems caused by the health status of energy storage batteries may lead to the performance degradation or complete failure of electrical equipment, resulting in huge hazards. How to achieve scientific and rapid estimation and prediction of battery health status is crucial. At present, for energy storage systems, establishing a digital twin model to map the operating conditions of the actual system can obtain the health status of each key device in advance, which is of great significance for further constructing a battery state monitoring and health management system. As the core component of the energy storage system, when establishing a digital twin model for the lithium battery pack, accurate characteristic parameters need to be obtained. Information such as voltage, SOC, and temperature can be obtained in real time through sensing means, but the internal electrochemical impedance spectrum is difficult to obtain through conventional means.

[0061] Based on their respective different characteristics, the current common methods for obtaining impedance information have different applicable scenarios and can be roughly divided into the following two types: non-intrusive and intrusive. The non-intrusive impedance detection technology mainly measures impedance parameters by using existing components or structures and matching hardware structures that conform to basic detection methods or principles without adding interference sources, such as the bridge method, resonance method, network analyzer method, etc.; the intrusive impedance detection technology is mainly divided into three categories: one is to use existing passive devices to perform corresponding switching operations to realize the construction, generation, and injection of disturbance signals; the second is to generate and controllably inject disturbance signals through existing active devices; the third is to generate a disturbance source through a specific module or device to achieve the purpose of disturbance injection.

[0062] However, the existing impedance detection methods have many shortcomings. Although the bridge measurement method is simple in principle, the actual measurement process is cumbersome and has many steps. In order to achieve system balance, it often takes too long to adjust. In addition, the overall hardware connection circuit of the bridge is complex and the detection range is narrow; although the principle of the resonant circuit method is simple and understandable, the adjustment time to find the resonance point is too long, and the actual use process is too cumbersome. At the same time, the resonance detection method places too high requirements on the system power supply and detection system, and the measurement range and applicable scenarios of this method are relatively limited; the measurement conditions of the network analyzer method are relatively harsh, and the actual transmission line cannot be a uniform system with constant unit parameters to be tested, and it cannot meet the premise requirements of uniformity and losslessness. At the same time, when using this method for measurement, the required equipment is too professional, the process is relatively complicated, and it is difficult to promote and use. When measuring communication lines and equipment, signals need to be matched, otherwise reflection interference will be introduced, and there are too many restrictions; the passive and active device switching method cannot accurately control the size and energy distribution of harmonics in a more detailed manner, and it is difficult to expand the scope of application; in an offline state, a disturbance source is generated through a specific module or device. This method has high test equipment costs, strict test environment requirements, and long test time. Traditional electrochemical impedance spectroscopy is usually completed in a laboratory electrochemical engineering station, which only supports impedance detection in an offline state, has a long test time, high cost, and strict test environment requirements.

[0063] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0064] The electrochemical impedance spectrum acquisition method based on the energy storage battery provided in the embodiment of the present application can be applied to Figure 1 In the application environment shown, the terminal 102 communicates with the server 104 through a network. The data storage system can store data that the server 104 needs to process. The data storage system can be integrated on the server 104, or placed on the cloud or other network servers.

[0065] The terminal 102 samples the DC bus side voltage, and the server 104 controls the terminal 102 to convert the DC bus side voltage into a DC voltage; the server 104 controls the terminal 102 to perform unipolar frequency multiplication modulation on the DC bus side voltage after the DC voltage conversion to obtain sinusoidal voltage disturbance signals at different frequencies; the sinusoidal voltage disturbance signals at different frequencies are input into the energy storage battery, and the terminal 102 samples to obtain the current response signal of the energy storage battery; the server 104 calculates the battery impedance at different frequencies based on the sinusoidal voltage disturbance signal and the current response signal; and obtains the electrochemical impedance spectrum of the energy storage battery pack based on the battery impedance at different frequencies.

[0066] The server 104 can be an independent physical server, a server cluster or a distributed system composed of multiple physical servers, or a cloud server providing cloud computing services.

[0067] In an exemplary embodiment, as Figure 2 shown, a method for obtaining the electrochemical impedance spectrum based on an energy storage battery is provided. Taking the method applied to the Figure 1 server in as an example for illustration, it includes the following steps S202 to step S210. Among them:

[0068] Step S202, sample the DC bus side voltage and perform DC voltage conversion on the DC bus side voltage.

[0069] Specifically, the DC bus side voltage is an important parameter in the energy storage system, usually a relatively high DC voltage (such as 750V). In this application, the DC bus voltage (Vdc) is the input power supply of the impedance detection device. To achieve impedance detection, it is first necessary to sample the DC bus voltage. The specific steps are as follows:

[0070] Generally, a high-precision voltage sensor (such as a Hall voltage sensor or a resistor divider) is used to sample the DC bus voltage. These sensors can convert the high-voltage signal into a low-voltage signal suitable for subsequent processing, while ensuring the accuracy and stability of the signal. The sampled DC bus voltage signal is sent to the computer as the DC bus status detection signal.

[0071] Since the DC bus voltage is relatively high (such as 750V), while the impedance detection device needs to work at a lower voltage (for example, the perturbation signal voltage injected into the battery is relatively low, about 10V), it is necessary to step down the DC bus voltage. This step is achieved through DC voltage conversion (DC / DC conversion), and an LLC resonant conversion circuit is used for step-down. The LLC resonant conversion circuit can achieve the step-down function by adjusting the transformer turns ratio, and at the same time achieve the function of electrical isolation. The stepped-down DC voltage is used as the input voltage of the H-bridge inverter circuit.

[0072] Step S204, perform single-pole frequency doubling modulation on the DC bus side voltage after DC voltage conversion to obtain the PWM signal of the switching tube at the corresponding frequency, and then obtain the sine voltage perturbation signal at different frequencies.

[0073] Among them, single-pole frequency doubling modulation is a pulse width modulation (PWM) technology used to generate high-frequency and low-distortion sine waveforms. Unipolar means that the modulation signal is modulated only on one polarity (positive or negative). Through a special modulation method, the equivalent switching frequency of the switching device is doubled, thereby reducing switching losses and output harmonics. It can generate high-quality sine waveforms and is suitable for precise signal injection and measurement.

[0074] Specifically, as Figure 3 shown, the modulation signal is a sine wave, and its frequency can be set to different values as needed (e.g., from low frequency to high frequency). The frequency of this sine wave determines the frequency of the perturbation signal injected into the energy storage battery.

[0075] The carrier signal is usually a high-frequency triangular wave or sawtooth wave. The frequency of the carrier is much higher than that of the modulation signal and is used to intersect with the modulation signal to generate a PWM signal. The core of single-pole frequency doubling modulation is to use two modulation waves with opposite polarities to intersect with the carrier. Specifically: Intersect the sine modulation wave with the carrier to generate a set of PWM signals. At the same time, intersect a modulation wave with the opposite polarity with the carrier to generate another set of PWM signals. In this way, a pair of modulation waves can generate two signals within one carrier cycle, doubling the equivalent switching frequency of the switching device. In the positive half cycle, after the modulation wave intersects with the carrier, the output voltage is only 0 and the positive amplitude (Ud). In the negative half cycle, after the modulation wave intersects with the carrier, the output voltage is only 0 and the negative amplitude (-Ud). In this way, the output PWM signal can obtain a sine voltage perturbation signal with adjustable amplitude and frequency after filtering.

[0076] Step S206, input the sine voltage perturbation signals at different frequencies into the energy storage battery, and sample to obtain the current response signal of the energy storage battery.

[0077] Specifically, inject the generated sine voltage perturbation signal into the energy storage battery through an impedance detection device (such as an H-bridge circuit). The H-bridge circuit can output a sine voltage signal with adjustable amplitude and frequency to ensure that the signal can be accurately applied to the battery. The injected sine voltage perturbation signal will cause corresponding current changes inside the battery, and these current changes reflect the response characteristics of the battery to signals at different frequencies. Set a current sensor at the output end or detection loop of the energy storage battery to measure the current response signal of the battery in real time.

[0078] Usually, a high-precision current sensor (such as a Hall current sensor or a shunt resistor) is used to measure the current. These sensors can convert the current signal into a voltage signal suitable for subsequent processing. The sampling device needs to have high precision and high dynamic response ability to ensure that the current response of the battery at different frequencies can be accurately measured.

[0079] Since the current response signal may be weak, it needs to be amplified by an amplifier to improve the signal-to-noise ratio. To remove noise and interference signals, usually, the sampled current signal needs to be filtered to ensure the purity of the signal. Convert the processed current signal into a digital signal through an analog-to-digital converter (ADC) for subsequent calculation and analysis.

[0080] Step S208: Calculate the battery impedance at different frequencies based on the sine voltage perturbation signal and the current response signal.

[0081] Specifically, the impedance (Z) in the electrochemical impedance spectroscopy (EIS) is the total resistance of the battery to an alternating current (AC) signal, including the ohmic resistance and polarization resistance of the battery. The impedance is defined as the ratio of the AC voltage (U) to the AC current (I), i.e., Z = U / I. For each frequency point, the magnitude of the impedance is the ratio of the voltage magnitude to the current magnitude, and the phase of the impedance is the difference between the voltage phase and the current phase.

[0082] Step S210: Obtain the electrochemical impedance spectrum of the energy storage battery pack based on the battery impedance at different frequencies.

[0083] Specifically, arrange the impedance values at different frequencies in the order of frequency to form a complete data set. Plot this data set on a coordinate graph, usually with frequency as the horizontal axis and impedance magnitude or phase as the vertical axis. In this way, the electrochemical impedance spectrum of the battery is obtained.

[0084] In the above method for obtaining the electrochemical impedance spectrum of the energy storage battery, by performing impedance spectrum detection during the normal operation of the energy storage system, it is possible to achieve real-time monitoring of the health state of the energy storage battery without shutdown or offline operation. This online monitoring method can timely detect potential problems of the battery and improve the reliability and safety of the energy storage system. Through the single-pole frequency doubling modulation technology, sine voltage perturbation signals at different frequencies can be generated and injected into the energy storage battery. This method can cover a wide range of frequencies, thereby obtaining more comprehensive battery impedance spectrum information and improving the detection accuracy and resolution. Integrating the impedance detection function into a power electronic converter (such as a PCS) avoids the complex equipment and high costs required for traditional offline detection. At the same time, through fast signal processing and calculation, the acquisition of the impedance spectrum can be efficiently completed, greatly shortening the detection time.

[0085] In an exemplary embodiment, the DC voltage conversion of the DC bus voltage includes:

[0086] Adopt an LLC resonant conversion circuit to perform DC voltage conversion on the DC bus voltage;

[0087] The single-pole frequency doubling modulation of the DC bus voltage after DC voltage conversion includes:

[0088] Adopt an H-bridge inverter circuit to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion;

[0089] Wherein, the voltage output end of the LLC resonant conversion circuit is connected to the DC voltage input end of the H-bridge inverter circuit.

[0090] Specifically, the LLC resonant conversion circuit is an efficient DC-DC converter used to convert a relatively high DC bus voltage into a lower DC voltage. The input of the LLC converter is the high voltage on the DC bus side (such as 750V). It outputs a lower DC voltage to provide a suitable input voltage for the subsequent H-bridge inverter circuit. For example, it converts 750V into a DC voltage of dozens of volts. The LLC converter achieves electrical isolation between the input and output through a transformer, ensuring the safety of the system, and has a high conversion efficiency, capable of achieving voltage conversion with low switching losses.

[0091] The output terminal of the LLC resonant conversion circuit is directly connected to the input terminal of the H-bridge inverter circuit, providing a stable DC voltage source for the H-bridge. The H-bridge inverter circuit is a DC-AC converter used to convert DC voltage into AC voltage. In this embodiment, the H-bridge inverter circuit is used to implement single-pole frequency doubling modulation to generate a sinusoidal voltage perturbation signal.

[0092] Among them, the sinusoidal voltage perturbation signal output by the H-bridge inverter circuit has the characteristics of adjustable amplitude and frequency, and is suitable for injecting into the battery for impedance detection. By adjusting the frequency of the modulation signal, a sinusoidal voltage perturbation signal covering a wide frequency range can be generated to meet the impedance detection requirements at different frequencies.

[0093] In this embodiment, the LLC resonant conversion circuit efficiently converts the high voltage on the DC bus side (such as 750V) into a low voltage suitable for the operation of the H-bridge inverter circuit. This conversion not only reduces the voltage level but also ensures high efficiency and low loss through soft-switching technology and isolation characteristics, while improving the safety and reliability of the system. The H-bridge inverter circuit uses single-pole frequency doubling modulation technology to further convert the converted low-voltage DC signal into a high-quality sinusoidal voltage perturbation signal with adjustable amplitude and frequency. This modulation method not only improves the purity of the output signal but also reduces high-frequency harmonics through frequency doubling technology, further enhancing the signal quality and meeting the requirements of impedance detection for signal accuracy.

[0094] In an exemplary embodiment, an H-bridge inverter circuit is used to perform single-pole frequency doubling modulation on the DC bus side voltage after DC voltage conversion, including:

[0095] Using an H-bridge inverter circuit, with a bipolar triangular carrier wave and two modulation waves with opposite polarities, perform single-pole frequency doubling modulation on the DC bus side voltage after DC voltage conversion to obtain the PWM signal of the switching tube at the corresponding frequency, and then obtain sinusoidal voltage perturbation signals at different frequencies.

[0096] Specifically, the H-bridge circuit consists of four switching devices (such as MOSFETs or IGBTs). By controlling the on and off states of these switching devices, the conversion from DC voltage to AC voltage can be achieved. The H-bridge inverter circuit converts the DC input voltage into a sinusoidal voltage perturbation signal with adjustable amplitude and frequency through the single-pole frequency-doubling modulation (SPFM) technique. Two modulation waves with opposite polarities are intercepted with a high-frequency triangular carrier wave to generate PWM signals. In the positive half-cycle, the output voltage is 0 or the positive amplitude; in the negative half-cycle, the output voltage is 0 or the negative amplitude. This modulation method doubles the switching frequency, reduces switching losses, and improves the quality of the output signal at the same time. Since two modulation waves with opposite polarities are used, two state transitions occur within each carrier cycle, doubling the equivalent switching frequency of the switching devices. This not only improves the quality of the output signal but also reduces high-frequency harmonics.

[0097] In this embodiment, through single-pole frequency-doubling modulation, using a bipolar triangular carrier wave and two modulation waves with opposite polarities, a high-quality sinusoidal voltage perturbation signal is generated. The generated signal has the characteristics of low harmonic distortion, wide frequency range, and high dynamic response, and is suitable for on-line impedance detection of energy storage batteries. This method not only improves the signal quality but also reduces system losses, improving the detection efficiency and reliability.

[0098] In an exemplary embodiment, sampling the DC bus voltage includes:

[0099] Sampling the DC bus voltage through a neutral-point clamped circuit with a T-type connection.

[0100] Among them, the neutral-point clamped circuit is a topology used in multilevel inverters and is commonly used in high-voltage and high-power applications. The NPC circuit with a T-type connection divides the DC bus voltage into multiple levels by introducing a neutral point, thereby achieving a smoother output voltage waveform and lower harmonic content.

[0101] Specifically, the NPC circuit divides the bus voltage into multiple levels by introducing a neutral point between the positive and negative poles of the DC bus, thereby achieving a smoother waveform. The multilevel output can reduce the harmonic content of the output voltage and improve the overall performance of the system. Usually, multiple switching devices (such as IGBTs or MOSFETs) and diodes are used to achieve the level switching and clamping functions. The neutral-point clamping function can effectively limit the transient change of the voltage and protect the circuit from overvoltage or undervoltage.

[0102] Sampling refers to obtaining the real-time value of the DC bus voltage through sensors or other measurement devices. In the NPC circuit, the sampling process needs to consider:

[0103] Sampling points are usually located at the positive pole, neutral point, and negative pole of the DC bus to obtain complete voltage information. By installing high-precision voltage sensors at these positions, the voltage status on the DC bus side can be monitored in real time.

[0104] In this embodiment, the multi-level output characteristic of the NPC circuit can effectively reduce the harmonic content, improve the overall performance and efficiency of the system. The neutral point clamping function can effectively limit the transient change of the voltage, protect the circuit from overvoltage or undervoltage, and improve the reliability and stability of the system.

[0105] It should be understood that although the steps in the flowcharts involved in the above-described embodiments are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-described embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same moment, but can be executed at different moments. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or steps or stages in other steps.

[0106] Based on the same inventive concept, the embodiments of the present application also provide an apparatus for obtaining the electrochemical impedance spectrum based on an energy storage battery for implementing the above-mentioned method for obtaining the electrochemical impedance spectrum based on an energy storage battery. The solution provided by this apparatus to solve the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the apparatus for obtaining the electrochemical impedance spectrum based on an energy storage battery provided below can refer to the limitations on the method for obtaining the electrochemical impedance spectrum based on an energy storage battery in the above text, and will not be repeated here.

[0107] In an exemplary embodiment, as Figure 4 shown, an apparatus for obtaining the electrochemical impedance spectrum based on an energy storage battery is provided. The apparatus includes a main circuit module 402, an impedance detection module 404, a calculation module 406, and an impedance spectrum acquisition module 408;

[0108] The impedance detection module 404 is configured to sample the voltage on the DC bus side through the main circuit module 402 and perform DC voltage conversion on the voltage on the DC bus side;

[0109] The impedance detection module 404 is configured to perform single-pole frequency doubling modulation on the voltage on the DC bus side after DC voltage conversion to obtain the PWM signal of the switching tube at the corresponding frequency, and further obtain the sinusoidal voltage perturbation signal at different frequencies;

[0110] The impedance detection module 404 is further configured to input sinusoidal voltage perturbation signals at different frequencies into the energy storage battery, and sample to obtain the voltage response signal and current response signal of the energy storage battery;

[0111] The calculation module 406 is configured to calculate the battery impedance at different frequencies according to the voltage response signal and current response signal;

[0112] The impedance spectrum acquisition module 408 is configured to obtain the electrochemical impedance spectrum of the energy storage battery pack according to the battery impedance at different frequencies.

[0113] In one embodiment, the impedance detection module 404 includes an LLC resonant conversion circuit and an H-bridge inverter circuit;

[0114] The LLC resonant conversion circuit is configured to sample and obtain the DC bus voltage through the main circuit module, and perform DC voltage conversion on the DC bus voltage;

[0115] The H-bridge inverter circuit is configured to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion to obtain the PWM signal of the switching tube at the corresponding frequency, and further obtain sinusoidal voltage perturbation signals at different frequencies;

[0116] Wherein, the voltage output end of the LLC resonant conversion circuit is connected to the DC voltage input end of the H-bridge inverter circuit.

[0117] In one embodiment, the H-bridge inverter circuit is specifically configured to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion by using a bipolar triangular carrier wave and two modulation waves with opposite polarities to obtain the PWM signal of the switching tube at the corresponding frequency, and further obtain sinusoidal voltage perturbation signals at different frequencies.

[0118] In one embodiment, the H-bridge inverter circuit includes a DC bus capacitor, an output inductor, an output capacitor, and four enhanced Nmos transistors; wherein, each enhanced Nmos transistor is connected in parallel with a freewheeling diode.

[0119] The most detailed embodiment of this application is:

[0120] As Figure 5 shown, the PCS system structure of the impedance detection module is shown, which is composed of Figure 5It can be seen that the system structure consists of a main circuit and an impedance detection module. The main circuit is a TNPC three-level topology, which controls the charging and discharging processes of the energy storage system and performs AC-DC conversion; the impedance detection module adopts a structure in which a DC / DC converter and a DC / AC converter are connected in series. The DC / AC converter injects a sinusoidal perturbation signal into the battery, and its circuit structure selects an H-bridge inverter circuit; the DC / DC converter reduces the DC bus voltage to an appropriate level and then connects it to the DC side of the H-bridge inverter circuit. Its circuit structure selects an LLC circuit, which mainly plays the role of isolation and step-down. The circuit structure of the impedance detection module is as Figure 3 shown:

[0121] Among them, V dc is the 750V DC bus voltage. Since the injected ripple voltage V C is relatively low, about 10V, the DC / DC converter is required to reduce the DC bus voltage to an appropriate level before connecting it to the H-bridge inverter circuit. The H-bridge inverter circuit outputs a sinusoidal voltage perturbation signal with adjustable amplitude and frequency and injects it into the battery.

[0122] The output modulation of the DC / AC converter adopts the method of single-pole double-frequency modulation. The principle is as Figure 6 shown. Two modulation waves with opposite polarities are used to modulate with a bipolar triangular carrier to generate PWM signals. In this modulation method, a pair of modulation waves can intersect with the carrier to generate two signals. When both S1 and S3 are at high level, the output voltage of the H-bridge inverter circuit is equal to the input voltage U d , and when one of S1 and S3 is at low level, the output voltage of the H-bridge inverter circuit is 0. In the positive half cycle, the high level of S1 is always wider than the low level of S3, and the output voltage is only 0 and U d ; similarly, in the negative half cycle, the output is only 0 and -U d . There are two state transitions within one carrier cycle, which can double the equivalent switching frequency of the switching device, so that the switching frequency harmonics in the output voltage move to high frequencies, reducing the values of the filter inductor and capacitor.

[0123] Figure 6 is a schematic diagram of the battery impedance spectrum detection method. After injecting a voltage perturbation signal into the energy storage battery through the H-bridge inverter circuit, the current response signal of the energy storage battery is obtained by sampling, and the battery impedance can be calculated according to the formula.

[0124] ;

[0125] In the formula, Z(jω) is the battery impedance at frequency ω, and U(jω) and I(jω) are the injected voltage perturbation signal and current response signal respectively. By setting the frequency of the sinusoidal modulation wave, different frequency perturbation voltage waveforms can be obtained. Thus, the battery impedance at a series of frequencies can be obtained, and the impedance spectrum of the battery can be obtained.

[0126] Each module in the above-mentioned device for obtaining the electrochemical impedance spectrum of the energy storage battery can be implemented by software, hardware, or a combination thereof. The main circuit module 402 and the impedance detection module 404 are designed in hardware form, and the circuit control and calculation parts are stored in the microprocessor in software form. The calculation module 406 and the impedance spectrum acquisition module 408 are stored in the microprocessor in software form.

[0127] In an exemplary embodiment, a microprocessor system is provided, and its internal structure diagram can be as Figure 7 shown. The microprocessor system includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the microprocessor system is used to provide computing and control capabilities. The memory of the microprocessor system includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the microprocessor system is used to store relevant data of the DC bus side voltage data, the sinusoidal voltage disturbance signal, and the current response signal. The input / output interface of the microprocessor system is used to exchange information between the processor and external devices. The communication interface of the microprocessor system is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements a method for obtaining the electrochemical impedance spectrum of an energy storage battery.

[0128] Those skilled in the art can understand that Figure 7 the structure shown in merely represents the block diagram of some structures related to the solution of the present application, and does not constitute a limitation on the microprocessor system to which the solution of the present application is applied. The specific microprocessor system may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0129] In an exemplary embodiment, a microprocessor system is provided, including a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, the following steps are implemented:

[0130] Sample the DC bus side voltage and perform DC voltage conversion on the DC bus side voltage;

[0131] Perform single-pole frequency doubling modulation on the DC bus side voltage after DC voltage conversion to obtain the PWM signal of the switching tube at the corresponding frequency, and then obtain the sinusoidal voltage disturbance signal at different frequencies;

[0132] Input sine voltage disturbance signals at different frequencies into the energy storage battery, and sample the current response signal of the energy storage battery;

[0133] Calculate the battery impedance at different frequencies according to the sine voltage disturbance signal and the current response signal;

[0134] Obtain the electrochemical impedance spectrum of the energy storage battery pack according to the battery impedance at different frequencies.

[0135] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0136] Adopt an LLC resonant conversion circuit to perform DC voltage conversion on the DC bus voltage;

[0137] Perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion, including:

[0138] Adopt an H-bridge inverter circuit to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion;

[0139] Among them, the voltage output end of the LLC resonant conversion circuit is connected to the DC voltage input end of the H-bridge inverter circuit.

[0140] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0141] Adopt an H-bridge inverter circuit, use a bipolar triangular carrier wave and two modulation waves with opposite polarities to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion, obtain the PWM signal of the switching tube at the corresponding frequency, and further obtain sine voltage disturbance signals at different frequencies.

[0142] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0143] Sample the DC bus voltage by adopting a neutral point clamping circuit in a T-type connection mode.

[0144] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0145] Sample the DC bus voltage and perform DC voltage conversion on the DC bus voltage;

[0146] Perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion, obtain the PWM signal of the switching tube at the corresponding frequency, and further obtain sine voltage disturbance signals at different frequencies;

[0147] Input sinusoidal voltage disturbance signals at different frequencies into the energy storage battery, and sample the current response signal of the energy storage battery;

[0148] According to the sinusoidal voltage disturbance signal and the current response signal, calculate the battery impedance at different frequencies;

[0149] According to the battery impedance at different frequencies, obtain the electrochemical impedance spectrum of the energy storage battery pack.

[0150] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented:

[0151] Adopt an LLC resonant conversion circuit to perform DC voltage conversion on the DC bus voltage;

[0152] Perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion, including:

[0153] Adopt an H-bridge inverter circuit to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion;

[0154] Among them, the voltage output end of the LLC resonant conversion circuit is connected to the DC voltage input end of the H-bridge inverter circuit.

[0155] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented:

[0156] Adopt an H-bridge inverter circuit, use a bipolar triangular carrier wave and two modulation waves with opposite polarities to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion, obtain the PWM signal of the switching tube at the corresponding frequency, and further obtain the sinusoidal voltage disturbance signals at different frequencies.

[0157] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented:

[0158] By adopting a neutral point clamping circuit in a T-type connection mode, sample the DC bus voltage.

[0159] In one embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by the processor, the following steps are implemented:

[0160] Sample the DC bus voltage and perform DC voltage conversion on the DC bus voltage;

[0161] Perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion, obtain the PWM signal of the switching tube at the corresponding frequency, and further obtain the sinusoidal voltage disturbance signals at different frequencies;

[0162] Input sinusoidal voltage perturbation signals at different frequencies into the energy storage battery, and sample the current response signal of the energy storage battery;

[0163] Calculate the battery impedance at different frequencies according to the sinusoidal voltage perturbation signal and the current response signal;

[0164] Obtain the electrochemical impedance spectrum of the energy storage battery pack according to the battery impedance at different frequencies.

[0165] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented:

[0166] Adopt an LLC resonant conversion circuit to perform DC voltage conversion on the DC bus voltage;

[0167] Perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion, including:

[0168] Adopt an H-bridge inverter circuit to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion;

[0169] Wherein, the voltage output end of the LLC resonant conversion circuit is connected to the DC voltage input end of the H-bridge inverter circuit.

[0170] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented:

[0171] Adopt an H-bridge inverter circuit to perform single-pole frequency doubling modulation on the DC bus voltage after DC voltage conversion by using a bipolar triangular carrier wave and two modulation waves with opposite polarities, obtain the PWM signal of the switching tube at the corresponding frequency, and further obtain the sinusoidal voltage perturbation signals at different frequencies.

[0172] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented:

[0173] Sample the DC bus voltage by adopting a neutral point clamping circuit in a T-type connection mode.

[0174] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use, and processing of relevant data need to comply with relevant regulations.

[0175] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in the present application can be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, data processing logics based on quantum computing, artificial intelligence (AI) processors, etc., without limitation.

[0176] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in the present application.

[0177] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A method for acquiring electrochemical impedance spectroscopy based on energy storage batteries, characterized in that: The method comprises: Sampling to obtain the DC bus side voltage, and performing DC voltage conversion on the DC bus side voltage; The DC bus side voltage after the DC voltage conversion is subjected to unipolar frequency multiplication modulation to obtain sinusoidal voltage disturbance signals at different frequencies; Inputting sinusoidal voltage disturbance signals at different frequencies into the energy storage battery, sampling and obtaining the current response signal of the energy storage battery; Calculating the battery impedance at different frequencies according to the sinusoidal voltage disturbance signal and the current response signal; According to the battery impedance at different frequencies, the electrochemical impedance spectrum of the energy storage battery pack is obtained.

2. The method according to claim 1, characterized in that The DC voltage conversion of the DC bus side voltage includes: Adopt LLC resonant conversion circuit to convert the DC bus side voltage into DC voltage; The unipolar frequency multiplication modulation of the DC bus side voltage after the DC voltage conversion comprises: An H-bridge inverter circuit is used to perform unipolar frequency multiplication modulation on the DC bus voltage after the DC voltage conversion; Wherein, the voltage output end of the LLC resonant conversion circuit is connected to the DC voltage input end of the H-bridge inverter circuit.

3. The method according to claim 2, characterized in that The H-bridge inverter circuit is used to perform unipolar frequency multiplication modulation on the DC bus side voltage after the DC voltage is converted, including: An H-bridge inverter circuit is used to perform unipolar frequency multiplication modulation on the DC bus voltage after DC voltage conversion using a bipolar triangle carrier and two modulation waves with opposite polarities, so as to obtain the PWM signal of the switch tube at the corresponding frequency, and then obtain the sinusoidal voltage disturbance signal at different frequencies.

4. The method according to claim 1, characterized in that: The sampling to obtain the DC bus side voltage includes: The DC bus side voltage is sampled and obtained by adopting a neutral point clamping circuit in a T-type connection mode.

5. An electrochemical impedance spectrum acquisition device based on energy storage battery, characterized in that: The device comprises a main circuit module, an impedance detection module, a calculation module and an impedance spectrum acquisition module; The impedance detection module is used to obtain the DC bus side voltage through sampling of the main circuit module, and perform DC voltage conversion on the DC bus side voltage; The impedance detection module is used to perform unipolar frequency multiplication modulation on the DC bus side voltage after the DC voltage conversion, to obtain the PWM signal of the switch tube at the corresponding frequency, and then to obtain the sinusoidal voltage disturbance signal at different frequencies; The impedance detection module is also used to input sinusoidal voltage disturbance signals at different frequencies into the energy storage battery, and sample to obtain voltage response signals and current response signals of the energy storage battery; The calculation module is used to calculate the battery impedance at different frequencies according to the voltage response signal and the current response signal; The impedance spectrum acquisition module is used to acquire the electrochemical impedance spectrum of the energy storage battery pack according to the battery impedance at different frequencies.

6. The device according to claim 5, characterized in that The impedance detection module includes an LLC resonant conversion circuit and an H-bridge inverter circuit; The LLC resonant conversion circuit is used to obtain the DC bus side voltage by sampling through the main circuit module, and perform DC voltage conversion on the DC bus side voltage; The H-bridge inverter circuit is used to perform unipolar frequency multiplication modulation on the DC bus side voltage after the DC voltage conversion, to obtain a PWM signal of the switch tube at a corresponding frequency, and then to obtain a sinusoidal voltage disturbance signal at different frequencies; Wherein, the voltage output end of the LLC resonant conversion circuit is connected to the DC voltage input end of the H-bridge inverter circuit.

7. The device according to claim 6, characterized in that The H-bridge inverter circuit is specifically used to use a bipolar triangle carrier and two modulation waves with opposite polarities to perform unipolar frequency multiplication modulation on the DC bus side voltage after the DC voltage is converted, to obtain a PWM signal of the switch tube at the corresponding frequency, and then to obtain a sinusoidal voltage disturbance signal at different frequencies.

8. The device according to claim 6, characterized in that The H-bridge inverter circuit comprises a DC bus capacitor, an output inductor, an output capacitor and four enhanced NMOS tubes; wherein each enhanced NMOS tube is connected in parallel with a freewheeling diode.

9. A microprocessor system, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 4 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

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