Method and device for regulating the ac injection current component of phase current of a battery system

Abstract

The present invention relates to a method for regulating an AC injection current component of a phase current of a battery system, comprising: In each pulse width modulation (PWM) cycle of the DC / DC converter, the collected stack current of the battery stack is analyzed to obtain the AC component amplitude of the stack current. Based on at least the AC component amplitude of the stack current and the expected AC component amplitude of the acquired stack current, the expected AC component of the phase current is adjusted as follows: Reduce the AC component amplitude of the stack current and the steady-state error between the acquired stack current's expected AC component amplitude; based at least on the expected AC component of the phase current and the acquired phase current, adjust the AC injection current into the phase current. The invention also relates to a device and computer program product for regulating the phase current of a battery system AC by injecting a current component. According to the present invention, the AC injection current component of phase current of the battery system can be precisely adjusted, enhancing the accuracy of the electrochemical impedance spectrum calculation for the battery stack.

Description

[0001] Specification

[0002] Method and Device for Regulating the AC Injection Current Component of Phase Current of a Battery System

[0003] Technical Field

[0004] This invention pertains to the field of batteries, specifically to a method for adjusting the AC injection current component of phase current of a battery system, a device for adjusting the AC injection current component of phase current of a battery system, and a computer program product that at least assists the steps of the method according to this invention.

[0005] Background Art

[0006] Fuel cells are highly efficient, environmentally friendly, and easy and flexible to assemble, but reliability is one of the key factors limiting their large-scale application. Electrochemical impedance spectrum is a crucial method for diagnosing faults in fuel cell systems. By measuring the electrochemical impedance spectrum of a fuel cell stack, one can infer the internal state of the fuel cell, including the water content of the proton exchange membrane, the liquid water content in the cathode, and the status of gas supply, among other factors.

[0007] Currently, most fuel cell system DC / DC converters are designed based on Buck and Boost circuits, utilizing digital pulse width modulation (PWM) for control. However, these DC / DC converters control the voltage and current signals of the output, with both input and output being smooth DC signals. When measuring the electrochemical impedance spectrum of a fuel cell stack, an AC signal needs to be applied. Therefore, the existing DC / DC converter control methods cannot meet the functional requirements for conducting electrochemical impedance spectrum analysis on fuel cell stacks.

[0008] Therefore, designing a control strategy for a DC / DC converter suitable for measuring the electrochemical impedance spectrum of battery stacks, especially fuel cell stacks, has become a pressing technical challenge that needs to be addressed.

[0009] Summary of Invention

[0010] The purpose of this invention is to provide a method for adjusting the AC injection current component of phase current of a battery system, a device for adjusting the AC injection current component of phase current of a battery system, and a computer program product to at least partially address the issues present in the current technology.

[0011] According to the first aspect of the present invention, a method is provided for regulating AC injection current component of phase current of a battery system, which may include the following steps:

[0012] - In each PWM cycle of the DC / DC converter within the battery system, analyze the collected stack current Is of the battery stack to obtain the AC component amplitude A_ISAC of the stack current Is.

[0013] - At least based on the AC component amplitude A_ISAC of stack current Is and the expected AC component amplitude A_ISAC* of the acquired stack current Is, adjust the expected AC component IPAC* of phase current IP of the DC / DC converter in such a way that: Reduce the steady-state error between the AC component amplitude A_ISAC of the stack current Is and the desired AC component amplitude A_ISAC* of the obtained stack current Is.

[0014] - at least based on the phase current IP expectation AC component IPAC* and the collected phase current IP adjust the AC injection current AC of phase current Ip.

[0015] The core idea of the present disclosure is as follows: In each PWM cycle of the DC / DC converter, the stack current Is of the battery stack is analyzed to obtain the AC component amplitude AJSAC of stack current Is. By reducing the steady-state error between AC component amplitude AJSAC of the stack current Is and the expected AC component amplitude A SAC* of the obtained stack current Is, the expected AC component IPAC* of the phase current IP is adjusted. Based on the expected AC component IPAC* and the collected phase current IP, the AC injection current component AC in the phase current IP can be adjusted, thereby enhancing the calculation accuracy of the electrochemical impedance spectrum of the battery stack, especially the fuel cell stack, laying a foundation for effectively improving the operational efficiency and lifespan of the battery system.

[0016] According to the second aspect of the present invention, a device is provided for adjusting the AC injection current component of phase current of a battery system, which is used to perform the method according to the present invention, wherein the device comprises the following components:

[0017] - A collection module, configured to collect the stack current Is of the battery stack and the battery system’s phase current IP of the DC / DC converter;

[0018] - An analysis module configured to process the stack current Is collected from the battery stack during each PWM cycle of the DC / DC converter in the battery system, yielding the AC component amplitude AJSAC of the stack current Is.

[0019] - Phase current AC component adjustment module, configured to regulate the desired AC component IPAC* of DC / DC converter’s phase current IP based on at least the amplitude of the AC component AJSAC of the stack current Is and the desired AC component amplitude AJSAC* of the acquired stack current Is. Reduce the steady-state error between AC component amplitude AJSAC of stack current Is and the expected AC component amplitude AJSAC* of the obtained stack current Is;

[0020] - AC injection current regulation module configured to adjust the injected AC injection current component AC of phase current IP at least based on AC component IPAC* of the phase current IP and the obtained phase current Ip.

[0021] According to a third aspect of the present disclosure, a computer program product is provided, such as a computer-readable program carrier comprising computer program instructions, wherein the execution of the computer program instructions by a processor at least assists in implementing the steps of the method according to the present disclosure.

[0022] Description of Accompanying Drawings

[0023] In the following, the present disclosure is described in greater detail with reference to the accompanying drawings to provide a better understanding of its principles, features, and advantages. The accompanying drawings include the following:

[0024] FIG. 1 illustrates a flowchart of a method for adjusting AC injection current component of phase current in a battery system according to an exemplary example of the present invention;

[0025] FIG. 2 illustrates a schematic block diagram of a battery system according to another exemplary example of the present invention;

[0026] FIG. 3 illustrates a schematic diagram of the parsing module according to another exemplary example of the present invention;

[0027] FIG. 4 illustrates a schematic diagram of the AC component adjustment module of phase current according to another exemplary example of the present invention;

[0028] FIG. 5 illustrates a schematic diagram of a phase current duty cycle adjustment module according to another exemplary example of the present invention;

[0029] FIG. 6 illustrates a flowchart of a method for adjusting the AC injection current components of phase current of a battery system, according to another exemplary example of the present invention;

[0030] FIG. 7 illustrates a schematic diagram of the phase current DC component adjustment module according to another exemplary example of the present invention;

[0031] FIG. 8 illustrates the topology of a DC / DC converter according to another exemplary example of the present invention;

[0032] FIG. 9 illustrates a flowchart of a method for adjusting AC injection current component of phase current of a battery system according to another exemplary example of the present invention; and

[0033] FIG. 10 illustrates a block diagram of a device for adjusting the AC injection current component of phase current of a battery system according to an exemplary example of the present invention.

[0034] Specific Embodiments

[0035] To provide a clearer understanding of the technical problems, technical solutions, and beneficial technical effects to be addressed by the present disclosure, the following detailed description of the present disclosure will be provided with reference to the accompanying drawings and multiple exemplary examples. It should be understood that the specific examples described herein are provided solely for the purpose of explaining the present disclosure and not for limiting the scope of protection of the present disclosure.

[0036] FIG. 1 illustrates a flowchart of a method for adjusting AC current component of phase current in a battery system according to an exemplary example of the present invention. The following exemplary examples describe the method in accordance with the present invention in more detail.

[0037] As shown in FIG 1 , the method may include steps S1 to S3. In step S1 , in each PWM cycle of the DC / DC converter 3 in the battery system 100, the collected stack current of the battery stack 2 is analyzed to obtain the AC component amplitude of the stack current. In the current example of this invention, the battery system 100 can particularly be a fuel cell system, or it may be other types of battery systems such as a lithium battery system. As shown in FIG 2, an exemplary example of a battery system 100 according to the present invention is illustrated in a schematic block diagram. The output voltage of the battery stack 2 (i.e. , stack voltage Us) is converted by DC / DC converter 3 into high-voltage direct current UH and delivered to the high-voltage supply network of the electric vehicle. The device 1 is connected to the input side of the DC / DC converter 3 and is configured to control the battery system’s 100 DC / DC converter 3. Here, you can use the collection module 11 of the device 1 to gather the stack current Is and stack voltage Us of the battery stack 2, and analyze the collected stack current Is to obtain the AC component amplitude AJSAC and AC component phase (p_lsAc.

[0038] The following, in conjunction with Figure 3, provides a detailed explanation of the schematic diagram of the analysis module according to another exemplary example of the present invention, elaborating on the analysis process of the stack current Is. As shown in 3, the collected stack current Is is input into the parsing module 12 for analysis. Suppose the expression for the collected stack current Is is:

[0039] Is= Acos(2nft + 0) + M

[0040] Among them, A represents the amplitude of the sinusoidal wave of the stack current Is, f denotes the frequency of the sinusoidal wave of the stack current Is, 0 indicates the phase of the sinusoidal wave of the stack current Is, M represents the DC component of the stack current Is.

[0041] Generated by the reference signal generator 121 of the parsing module 12, a first reference signal Ri is produced, and the phase shifter 122 performs a phase shift on the first reference signal Ri, such that the second reference signal R2 is phase-shifted by 90° relative to the first reference signal Ri. First reference signal Ri and second reference signal R2 have a frequency f that can match the sinusoidal frequency of the stack current Is, which can be expressed by the following formula:

[0042] Ri = 2 cos(2nft)

[0043] R2= — 2 sin(2nft)

[0044] Multiply the stack current Is with the first reference signal Ri and pass it through the first low-pass filter LPF of the low-pass filter 123 to obtain the first intermediate parameter X. Multiply the stack current Is with the second reference signal R2 and pass it through the low- pass filter 124 of the second low-pass filter LPF to obtain the second intermediate parameter Y. This calculation can be represented by the following formula:

[0045] X = LPF(Ri x Is) = Acos(O)

[0046] Y = LPF(R2x ls) = Asin(O)

[0047] Next, through the first calculation step 125, the AC component amplitude AJSAC of the stack current Is is calculated, and through the second calculation step 126, the AC component phase (PJSAC of the stack current Is is determined. This achieves the analysis of the stack current Is. The calculation processes of the first calculation step 125 and the second calculation step 126 can be represented by the following formulas:

[0048] AJSAC = Vx2+ Y2

[0049] CP SAC=arctan Y / X

[0050] Alternatively, the stack voltage Us can be analyzed using the aforementioned method to obtain the AC component amplitude A_USAC of stack voltage Us and the AC component phase <P_USAC of the stack voltage Us.

[0051] In step S2, it is possible to adjust the desired AC component IPAC* of the phase current IP of the DC / DC converter based at least on AC component amplitude AJSAC of the stack current Is and the desired AC component amplitude A SAC* of the obtained stack current Is in such a way that: Reduce the steady-state error between AC component amplitude AJSAC of stack current Is and the obtained expected AC component amplitude AJSAC* of stack current Is. This step S2 can be achieved through the phase current AC component adjustment module 13. The following is a detailed explanation based on the schematic diagram of the phase current AC component adjustment module 13 shown in FIG 4, according to another exemplary example of this invention. As shown in FIG 4, the desired AC component amplitude A_ISAC* of the stack current Is can be obtained from the control unit of the battery system 100 (not shown here), which can be determined by the control unit of the battery system 100 in the following manner: In the battery stack 2, under the premise that the calculation accuracy of the impedance meets the preset standards, the expected AC component amplitude AJSAC* of the stack current Is is determined to be sufficiently small, ensuring that the AC component of the stack current Is does not affect the stable operational state of the battery stack 2.

[0052] Here, the difference signal between the desired AC component amplitude AJSAC* of the stack current Is and the AC component amplitude AJSAC of the stack current Is is adjusted through a PI control unit 131 to reduce the steady-state error between the AC component amplitude AJSAC of the stack current Is and the desired AC component amplitude AJSAC*. The adjusted difference signal is then modulated by multiplying it with a periodic signal generated by the signal generator 132, thereby obtaining the adjusted desired AC component IPAC* of phase current IP of DC / DC converter 3. The periodic signal can be, for example, a sine wave generated using the internal clock signal of the signal generator chip.

[0053] Optionally, the difference signal of expected AC component amplitude AJSAC* of stack current Is and AC component amplitude AJSAC of stack current Is can also be adjusted through a trained mathematical model, thereby reducing the steady-state error between the expected AC component amplitude AJSAC of stack current Is and the obtained expected AC component amplitude AJSAC* of stack current Is. It should be noted that the AC component amplitude of stack current Is of the battery system and AC component of phase current IP have a corresponding mathematical relationship that can be expressed with mathematical expressions under different DC / DC converter operating modes. Therefore, the mathematical model can be trained based on pre-collected experimental data, and the trained mathematical model can be used to achieve the purpose of reducing the steady-state error through adjustment. The mathematical model includes, but is not limited to, machine learning models, convolutional neural networks, and more.

[0054] In step S3, based at least on the desired AC component IPAC* of the phase current IP and the acquired phase current IP, adjust the AC injection current component AC injected into the phase current Ip. The adjustment process can be achieved using the duty cycle adjustment module 151 and the converter control module 152. In the duty cycle adjustment module 151 , the switching signal duty cycle D of the DC / DC converter 3 can be adjusted based on at least the desired AC component IPAC* of the phase current IP and the collected phase current Ip. In the converter control module 152, the DC / DC converter 3 can be controlled based on the switching signal duty cycle D, to adjust the AC injection current component AC in the phase current Ip.

[0055] Below, in conjunction with FIG 5, a detailed explanation is provided for the schematic diagram of the phase current duty cycle adjustment module 151 according to another exemplary example of the present invention.

[0056] Considering that during the chopping process of the transistor in DC / DC converter 3, the phase current flowing through the phase inductance of DC / DC converter 3 can generate significant ripples, in each PWM cycle, the sampling module 11 can perform multiple samplings of the phase current flowing through the phase inductance of DC / DC converter 3 and calculate the average value. This results in the phase current I P of the DC / DC converter 3 associated with that PWM cycle. Next, calculate the DC / DC converter 3’s desired phase current IP* (in this example, the desired phase current IP* only includes the phase current IP’S desired AC component IPAC*) and the difference signal with the acquired phase current Ip. Input the difference signal into the PIR control loop to adjust the DC / DC converter 3’s switching signal duty cycle D. Here, through PR control step 1512, a regulated AC injection current component AC can be introduced into the phase current Ip. Using this AC injection current component AC, the electrochemical impedance spectrum of the battery stack 2 can be calculated.

[0057] FIG 6 illustrates a flowchart of a method for adjusting the AC injection current component of phase current of a battery system according to another exemplary example of the present invention. Only the differences with the examples shown in FIG. 1 are set forth below, while the same steps are not repeated for brevity.

[0058] As shown in FIG 6, the method may also include steps S4 to S6. In step S4, at least based on the collected stack current IS‘s DC component ISDC and the expected DC component ISDC* of the obtained stack current Is, adjust the expected DC component IPDC* of the phase current Ip. This step S4 can be implemented through the phase current DC component adjustment module 14. The following provides a detailed explanation in conjunction with FIG 7, which illustrates a schematic diagram of the phase current DC component adjustment module 14 according to another exemplary example of the present invention.

[0059] As shown in FIG 7, the desired DC component ISDC* of the stack current Is can be obtained from the control unit (not shown here) of the battery system 100. For example, this can be set by the control unit of the battery system 100 based on the power demands and status parameters of the battery system. Through the acquisition module 11 (such as a high- precision current sensor), the stack current Is’s DC component ISDC is collected, and the difference signal between the stack current Is’s DC component ISDC and the expected DC component ISDC* is input into the PI control module 141 to reduce the steady-state error of the stack current Is’s DC component ISDC, and the phase current IP’S expected DC component IPDC* is output as the output signal.

[0060] In step S5, at least the desired DC component IPDC* of the phase current IP and the acquired phase current IP adjust the duty cycle D of the switching signal of the DC / DC converter 3. In step S6, the DC / DC converter 3 is controlled based at least on the duty cycle D of the switching signal to adjust the DC component IPDC of the phase current IP, thereby achieving regulation of the phase current IP flowing through the phase inductor L in each PWM cycle using the duty cycle D of the switching signal.

[0061] For example, in the schematic diagram shown in FIG 5 illustrating another exemplary example of the phase current duty cycle adjustment module 151 according to the present invention, the desired AC component IPAC* of the phase current IP can be obtained along with the desired DC component IPDC*, resulting in the desired phase current IP* of the DC / DC converter 3. This involves calculating the difference signal between the desired phase current IP* (in this example, the sum signal) and the collected phase current Ip. The difference signal is then input into the PIR control segment to adjust the duty cycle D of the switching signal of the DC / DC converter 3. Here, the differential signal is input into the PI control step 1511 , through which the PI control step 1511 can eliminate the steady-state error of the phase current IP’S DC component. Considering the significant ripple in the phase current IP of the phase inductor flowing through the DC / DC converter 3, even though the phase current IP is the average value obtained from multiple samples within a PWM cycle, these sampled values still have a considerable ripple. The phase current IP derived from these samples has a certain steady-state error. Simultaneously, the differential signal is also input into the PR control step 1512, through which the PR control step 1512 can generate the AC injection current component AC to be injected into the phase current Ip.

[0062] Particularly in DC / DC converters 3 configured as BUCK-BOOST converters, DC / DC converter 3 switches between different operating modes based on the relationship between input and output voltage. Therefore, the DC / DC converter 3 can allocate adjusted duty cycles of switching signals to its transistors based on its operating mode, allowing for the regulation of the injected phase current IP in AC injection current component AC and I or the DC component IPDC of the phase current Ip. Below, in conjunction with FIG 8, illustrates the topology of a DC / DC converter according to another exemplary example of the present invention, detailing the aforementioned regulation process.

[0063] FIG 8 illustrates the topology of a single-phase BUCK-BOOST converter, which includes four transistors D1-D4 (e.g., silicon carbide-based field-effect transistors), two stabilizing capacitors C1 , C2 and a phase inductor L. Battery stack 2 stack current Is serves as the input current from DC / DC converter 3 on the left side input. Due to the presence of a stabilizing capacitor C1 on the input side, the AC component of the stack current Is is relatively small compared to the DC component, while the phase current flowing through the DC / DC converter 3 has significant ripple due to the chopping control of the transistor.

[0064] DC / DC converter 3 can switch between different operating modes of a BUCK-BOOST converter based on the relationship between the input and output voltages of the DC / DC converter, including BUCK mode, BOOST mode, and BUCK-BOOST mode. For example, when the input voltage exceeds the output voltage by a preset threshold, DC / DC converter 3 can operate in BUCK mode, where the first transistor D1 functions as the main control transistor for chopping control, and the fourth transistor D4 remains continuously on; when the input voltage is less than the output voltage by another preset threshold, DC / DC converter 3 can operate in BOOST mode, where the third transistor D3 functions as the main control transistor for chopping control, and the first transistor D1 remains continuously on; when the deviation between the input and output voltage is less than the aforementioned preset threshold, DC / DC converter 3 can operate in BUCK-BOOST mode, with both the first transistor D1 and the third transistor D3 acting as main control transistors for chopping control.

[0065] When the DC / DC converter 3 operates in BOOST mode, since the first transistor D1 remains continuously on, meaning the duty cycle of the first transistor D1 is maintained at 100%, during the process of injecting AC current component AC into the phase current IP through the PR control section 1512, the amplitude of the stack current Is remains consistent with the amplitude of the phase current Ip. When the DC / DC converter 3 operates in BUCK mode or BUCK-BOOST mode, the first transistor D1 acts as the main control transistor for chopper control, or both the first transistor D1 and the third transistor D3 serve as main control transistors for chopper control. This means the duty cycle of the first transistor D1 is less than 100%. Therefore, during the process of injecting the AC current component AC into the phase current IP through the PR control section 1512, the AC component of the stack current Is will attenuate, leading to a deviation between the amplitude of the AC component of the stack current Is and the amplitude of the AC component of the phase current Ip. Typically, the amplitude of the AC component of the stack current lsis less than that of the phase current Ip. The control strategies of existing DC / DC converters struggle to precisely control the amplitude of the AC component of the stack current Is, which affects the calculation accuracy of the electrochemical impedance spectrum of the battery stack 2.

[0066] In the configuration of this invention, during each DC / DC converter 3 PWM cycle, the stack current Is is analyzed to obtain the AC component amplitude AJSAC of the stack current Is, which is introduced as a control factor to adjust the duty cycle D of the switching signal of the DC / DC converter 3. Based on the operating mode of the DC / DC converter 3, the adjusted duty cycle D is allocated to the first transistor D1 and the third transistor D3 of the DC / DC converter 3, while the second transistor D2 and the fourth transistor D4 are controlled for synchronous rectification to enhance the efficiency of the DC / DC converter 3. This is used to adjust in real-time the AC injection current component AC in the phase current Ip.

[0067] The purpose of control the stack current Is’s AC component amplitude, thereby effectively enhancing the calculation accuracy of the battery stack 2’s electrochemical impedance spectrum. Optionally, it is also possible to adjust the phase current IP’S DC component lPDc, thereby regulating the stack current Is’s DC component ISDC, thus controlling the output power of the battery stack 2.

[0068] FIG 9 illustrates a flowchart of a method for adjusting the AC injection current component of phase current of a battery system according to another exemplary example of the present invention. Only the differences with the examples shown in FIG. 6 are set forth below, while the same steps are not repeated for brevity.

[0069] The method may also include the step S7. In step S7, based at least on the collected stack current Is and stack voltage Us of the battery stack 2, the impedance Zs of the battery stack 2 is calculated. For example, it can be assumed that the collected stack current Is and stack voltage Us are expressed as:

[0070] Is= Asin(2nft + 0- + M

[0071] Us= B sin(2nft + 02) + N

[0072] Among them, A represents the sinusoidal amplitude of the stack current Is, f represents the sinusoidal frequency of the stack current Is and stack voltage Us, 01 represents the sinusoidal phase of the stack current Is, M represents the DC component of the stack current Is, B represents the sinusoidal amplitude of the stack voltage Us, 02 represents the sinusoidal phase of the stack voltage Us, N represents the DC component of the stack voltage Us. Then, the impedance Zs of battery stack 2 can be calculated using the following formula:

[0073] Among them, j represents the imaginary unit.

[0074] This method allows for obtaining the electrochemical impedance spectrum of the battery stack 2. Based on this electrochemical impedance spectrum, it is possible to infer the internal state of the fuel cell, including the water content of the proton exchange membrane, the cathode liquid water content, the gas supply status, and so on, thereby enhancing the operational efficiency and lifespan of the fuel cell system.

[0075] In addition, it should be noted that the serial numbers of the steps described herein do not necessarily represent a sequential order, but are merely reference numerals. Depending on the circumstances, the order may be changed as long as it achieves the technical objectives of the present disclosure.

[0076] FIG 10 illustrates a block diagram of a device 1 for adjusting the AC injection current component of phase current of a battery system according to an exemplary example of the present invention.

[0077] As shown in FIG 10, the device 1 may include the following components:

[0078] Collection module 11 , configured to collect the stack current Is of the battery stack 2 and the phase current IP of the DC / DC converter 3;

[0079] Analysis Module 12, configured to analyze the stack current Is of the collected battery stack 2 during each PWM cycle of the DC / DC converter 3 in the battery system to obtain the AC component amplitude AJSAC of the stack current Is.

[0080] Phase current AC component adjustment module 13, configured to adjust the desired DC / DC converter phase current IP’S AC component IPAC* based at least on AC component amplitude AJSAC of the stack current Is and the desired AC component amplitude A SAC* of the acquired stack current Is, in such a way that: Reduce the steady-state error between stack current Is’s AC component amplitude AJSAC and the obtained stack current Is’s desired AC component amplitude AJSAC*; and

[0081] AC injection current regulation module 15, configured to, based on the IP’S AC injection current component IPAC* and obtained phase current IP, adjust the AC injection current component AC of phase current Ip.

[0082] Optionally, the device 1 may also include a phase current DC component adjustment module 14, which is configured to adjust the desired DC component IPDC* of the phase current IP based on at least the collected stack current Is’s DC component ISDC and the desired DC component ISDC* of the obtained stack current Is.

[0083] Optionally, the AC injection current regulation module 15 may include: Duty cycle adjustment module 151 , configured to adjust the duty cycle of the switching signal D of the DC / DC converter based at least on the collected phase current IP and the desired AC component IPAC* and I or the desired DC component IPDC* of the phase current IP; Converter control module 152, configured to control the DC / DC converter 3 based at least on the duty cycle of the switching signal D, in order to adjust the AC injection current component AC and I or the DC component IPDC injected into the phase current Ip.

[0084] Optionally, the device 1 may also include an impedance calculation module 16, which is configured to calculate the impedance Zs of the battery stack 2 based at least on the stack current Is and stack voltage Us of the battery stack 2, where the stack voltage Us of the battery stack 2 can be acquired through the collection module 11.

[0085] In addition, it should be understood that in this document, terms such as “first,” “second,” “third,” etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, such terms should not be understood as implying a specific quantity of the indicated technical features.

[0086] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the present disclosure, even when described with respect to specific features of individual embodiments. The examples of features provided in the present disclosure are intended to be illustrative and not limiting, unless otherwise specified. In a specific implementation, multiple features may be combined with one another as per actual requirements and when technically feasible. Various substitutions, alterations, and modifications may be conceived without departing from the spirit and scope of the present disclosure.

Claims

Claims1 . A method for regulating the AC injection current of phase current of a battery system, comprising the following steps:In each PWM cycle of the DC / DC converter (3) in the battery system, the collected stack current Is of the battery stack (2) is analyzed to obtain the AC component amplitude A_ISAC of the stack current Is. at least based on the stack current Is’s AC component amplitude AJSAC and the obtained expected AC component amplitude of the stack current AJSAC*, adjust the expected DC / DC converter’s phase current IP AC component IPAC*, in such a way that: reduce the AC component amplitude AJSAC of stack current Is and the expected AC component amplitude AJSAC* of acquired stack current Is between the steady-state error; and at least based on the phase current IP expectation AC component IPAC* and the collected phase current IP adjust the AC injection current AC of phase current Ip.

2. According to Claim 1 , the method is characterized by adjusting the duty cycle D of the switching signal of the DC / DC converter (3) at least based on the desired AC component IPAC* of the phase current IP and the acquired phase current IP, and based on the duty cycle of the switching signal D, the DC / DC converter (3) is controlled to adjust the AC injection current component AC injected into the phase current Ip.

3. According to Claim 1 , the method is characterized by adjusting the difference signal between the desired AC component amplitude AJSAC* of the acquired stack current IS and the AC component amplitude AJSAC of the stack current IS through a PI control step and / or a trained mathematical model, to reduce the steady-state error between the AC component amplitude AJSAC of the stack current Is and the desired AC component amplitude AJSAC*, and multiplying the adjusted difference signal by a periodic signal generated by a signal generator, thereby obtaining the adjusted DC / DC converter (3) phase current IP desired AC component IPAC*.

4. According to any one of Claims 1 to 3, wherein the method further comprises: at least based on the collected stack current Is of DC component ISDC and the expected DC component ISDC* of the acquired stack current Is, adjust the expected DC component IPDC* of the phase current IP, at least the expected DC component IPDC* of the phase current IP and the collected phase current IP adjust the duty cycle D of the switching signal of the DC / DC converter (3) ; andat least based on the duty cycle D of the switch signal to control the DC / DC converter (3), in order to regulate the DC component IPDC of the phase current Ip.

5. The method according to Claim 4, characterized in that at least based on the collected stack current Is’s DC component ISDC and the desired DC component ISDC* of the acquired stack current Is, the phase current DC component adjustment module (14) adjusts the desired DC component IPDC* of the phase current IP, wherein the phase current DC component adjustment module (14) includes a PI control element to reduce the steady-state error of the DC component ISDC of the stack current Is.

6. According to Claim 4, the method is characterized by adjusting the duty cycle D of the switching signal of the DC / DC converter (3) through a duty cycle adjustment module (15) based at least on the collected phase current IP and the desired AC component IPAC* and I or the desired DC component IPDC* of the phase current IP, wherein the duty cycle adjustment module (15) includes a PI control step to reduce the steady-state error of the DC component of the phase current IP and a PR control segment to generate the AC injection current component AC-7. According to Claim 4, the method is characterized by adjusting the duty cycle D of the switching signal allocated to the transistors of the DC / DC converter (3) based on its operating mode to regulate the AC injection current component AC and / or the DC component IPDC of the phase current Ip.

8. According to the method of any one of Claims 1 to 3, wherein the stack current Is is modulated by multiplying with a first reference signal Ri and low-pass filtered to obtain the first intermediate parameter X, and the stack current Is is modulated by multiplying with a second reference signal R2 and low-pass filtered to obtain the second intermediate parameter Y. The second reference signal R2 is phase-shifted by 90° relative to the first reference signal R1. The AC component amplitude AJSAC of the stack current Is is calculated using the formula x2+ Y2as, and the AC component phase of the stack current Is is calculated using the formula arctan YX as (p_lsAc, thereby achieving the analysis of the stack current Is.

9. According to any one of Claims 1 to 3, wherein the method further comprises the following steps: at least based on the collected battery stack (2) stack current Is and stack voltage Us, calculate the impedance Zs of the battery stack (2).

10. A device for regulating the phase current of a battery system AC injection current component (1), the device (1) is used to perform the method according to any one of Claims 1 to 9, wherein the device (1) comprises the following components: a collection module (11), configured to collect the stack current Is of the battery stack (2) and the phase current IP of the DC / DC converter (3) of the battery system; the analysis module (12) is configured to analyze the stack current Is of the collected battery stack (2) during each PWM cycle of the DC / DC converter (3) in the battery system, obtaining the AC component amplitude A_ISAC of the stack current Is, phase current AC component adjustment module (13), configured to adjust the desired AC component IPAC* of DC / DC converter phase current IP based at least on the stack current Is’s AC component amplitude AJSAC and the acquired desired AC component amplitude A_ISAC* of the stack current Is, in such a way that: Reduce the AC component amplitude A SAC of stack current Is of and the steady-state error between the acquired stack current Is and expected AC component amplitude A SAC*; andAC injection current regulation module (15), configured to regulate the AC injection current component AC injected into the phase current IP based on at least the desired AC component IPAC* and the acquired phase current IP.11 . According to Claim 10, the device (1) is characterized in that the device (1) further includes a phase current DC component adjustment module (14), which is configured to adjust the desired DC component IPDC* of the phase current Is based on at least the acquired DC component ISDC of stack current Is and the desired DC component ISDC* of the stack current Is.

12. According to Claim 11 , the device (1) is characterized in that the AC injection current regulation module (15) includes: duty cycle adjustment module (151), configured to adjust the duty cycle D of the switching signal of the DC / DC converter based on at least the acquired phase current I P and the desired AC component IPAC* and / or the desired DC component IPDC* of the phase current IP; and converter control module (152), configured to control the DC / DC converter (3) based on at least the duty cycle D of the switching signal, to adjust the AC injection current component AC and / or the DC component IPDC of the phase current Ip.

13. According to any one of Claims 10 to 12, the described device (1) is characterized in that the acquisition module (11) is further configured to collect the stack voltage Us of the battery stack (2), and the device (1) also includes an impedance calculation module (16), which is configured to calculate the impedance Zs of the battery stack (2) based at least on the collected stack current Is and stack voltage Us.

14. A computer program product, such as a computer-readable program carrier comprising computer program instructions, wherein the execution of the computer program instructions by a processor at least assists in implementing the steps of the method according to any of Claims 1 to 9.

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