Method, apparatus, storage medium, and system for controlling a power converter

Abstract

A method for controlling at least one power converter is disclosed, the method including: generating at least one electrochemical impedance spectra (EIS) reference signal, each of the at least one EIS reference signals having a frequency selected for EIS, superimposing the at least one EIS reference signal on at least one control reference signal to generate at least one superimposed reference signal, controlling the at least one power converter based on the at least one superimposed reference signal to respectively charge / discharge the at least one battery module, obtaining at least one response signal generated by the at least one battery module, and calculating at least one EIS signal for each of the at least one battery module based on the at least one superimposed reference signal and the at least one response signal.

Description

[Technical Field]

[0001] Technical Field The present disclosure relates to the field of power conversion, and more particularly to methods, apparatus, computer-readable storage media, and systems for controlling at least one power converter. [Background technology]

[0002] background In recent years, electrochemical impedance spectroscopy (EIS) has been widely used to monitor the state of health of batteries due to its high accuracy. EIS is a non-destructive measurement that can not only provide detailed dynamic information inside the battery, but can also be used to monitor changes in battery characteristics under different usage or storage conditions.

[0003] However, specially designed equipment is usually required to obtain EIS information. Because the specially designed equipment is used only for EIS, the battery health status can only be tested through an offline monitoring process. To date, no online EIS monitoring process for the battery health status has been developed, which limits the application of EIS, especially in battery energy storage systems (BESSs) with power converters.

[0004] A Battery Energy Storage System (BESS) is generally known as a combination of one or more power converters, a Battery Management System (BMS), and battery modules. Typically, in a BESS, one or more power converters are connected between a power grid and a battery module. One of the functions of the power converter is to charge or discharge power between the power grid and the battery module. A Battery Management System (BMS) may be a system connected to the battery module and can communicate with a power converter controller or a higher-level controller in the BESS or power grid management system. The functions of the BMS may include estimating the State of Charge (SOC) of the battery modules, monitoring the status of battery temperature, current, and voltage, and balancing the SOC of different battery modules. Summary of the Invention [Problem to be solved by the invention]

[0005] overview The present disclosure provides a method, apparatus, computer-readable storage medium, and system for controlling at least one power converter. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, a method for controlling at least one power converter is disclosed, the method including generating at least one electrochemical impedance spectra (EIS) reference signal, each having a frequency selected for EIS, superimposing the at least one EIS reference signal on at least one control reference signal to generate at least one superimposed reference signal, controlling the at least one power converter based on the at least one superimposed reference signal to charge / discharge at least one battery module, respectively, obtaining at least one response signal generated by the at least one battery module, and calculating at least one EIS for each of the at least one battery module based on the at least one superimposed reference signal and the at least one response signal.

[0007] According to one embodiment, the at least one battery module each includes at least one battery cell connected in series, and the at least one response signal each includes a voltage signal generated across a respective one of the at least one battery cell. According to one embodiment, charging / discharging the battery module based on the superimposed reference signal includes controlling a charge / discharge current.

[0008] According to one embodiment, each of the at least one battery modules includes at least one battery string connected in parallel, each battery string including at least one battery cell, and each of the at least one response signals includes a current signal output from a respective one of the at least one battery strings. According to one embodiment, charging / discharging the battery modules based on the superimposed reference signal includes controlling a charge / discharge voltage across the at least one battery string.

[0009] According to one embodiment, generating the at least one EIS reference signal includes pulse-width modulating the EIS reference signal.

[0010] According to one embodiment, the number of the at least one battery module is an integer multiple of two, and the EIS reference signals for each of the two power converters are spaced apart by a 180-degree phase shift.

[0011] According to one embodiment, the number of the at least one battery modules is N, an odd number greater than two, and the corresponding EIS reference signals are spaced apart by a phase shift of 360 degrees divided by N.

[0012] According to one embodiment, the method further includes deriving state information regarding a state of health of each of the at least one battery module using each of the at least one calculated EIS.

[0013] According to one embodiment, obtaining the at least one response signal is performed by a battery management system (BMS).

[0014] According to one embodiment, the at least one power converter each comprises power electronic components comprising silicon carbide.

[0015] According to one embodiment, the at least one control reference signal includes an inertial reference signal, a fast frequency support reference signal, a frequency control auxiliary service reference signal, a network support reference signal, and / or a charge / discharge reference signal.

[0016] According to a further aspect of the present disclosure, an embodiment of the present disclosure discloses an apparatus for controlling at least one power converter, the apparatus including means for performing the method described above.

[0017] According to a further aspect of the present disclosure, an embodiment of the present disclosure discloses a computer-readable storage medium, the computer-readable storage medium including instructions that, when executed by a processor, cause the processor to perform the method described above.

[0018] According to a further aspect of the present disclosure, an embodiment of the present disclosure discloses a system for controlling at least one power converter, the system including at least one power converter, at least one battery module, and a controller having means for performing the above-described method.

[0019] The present disclosure further relates to a method for controlling at least one power converter coupled to a power grid, the method including: generating at least one electrochemical impedance spectra (EIS) reference signal to be externally injected into the power grid, the at least one EIS reference signal each having a frequency selected for EIS; superimposing the at least one EIS reference signal on at least one control reference signal to generate at least one superimposed reference signal; controlling the at least one power converter based on the at least one superimposed reference signal to charge / discharge the at least one battery module, respectively; obtaining at least one response signal generated by the at least one battery module, respectively; and calculating at least one EIS for each of the at least one battery module based on the at least one superimposed reference signal and the at least one response signal. A battery management system (BMS) employed within the battery energy storage system (BESS) is communicatively coupled to the at least one battery module such that the at least one response signal generated by the at least one battery module is obtained.

[0020] According to one embodiment, each of the at least one battery modules comprises at least two battery cells connected in series, and each of the at least one response signals comprises a voltage signal generated across a respective one of the at least one battery cells. According to one embodiment, charging / discharging the battery module based on the superimposed reference signal comprises controlling a charge / discharge current.

[0021] According to one embodiment, each of the at least one battery modules includes at least two battery strings connected in parallel, each battery string including at least one battery cell, and each of the at least one response signal includes a current signal output from a respective one of the at least one battery strings. According to one embodiment, charging / discharging the battery modules based on the superimposed reference signal includes controlling a charge / discharge voltage across the at least one battery string.

[0022] According to one embodiment, generating the at least one EIS reference signal includes pulse-width modulating the EIS reference signal.

[0023] According to one embodiment, the number of the at least one battery module is an integer multiple of two, and the EIS reference signals for each of the two power converters are spaced apart by a 180-degree phase shift.

[0024] According to one embodiment, the number of the at least one battery modules is N, an odd number greater than two, and the corresponding EIS reference signals are spaced apart by a phase shift of 360 degrees divided by N.

[0025] According to one embodiment, the method further includes deriving state information regarding a state of health of each of the at least one battery module using each of the at least one calculated EIS.

[0026] According to one embodiment, obtaining the at least one response signal is performed by a battery management system (BMS).

[0027] According to one embodiment, the at least one power converter each comprises power electronic components comprising silicon carbide.

[0028] According to one embodiment, the at least one control reference signal includes an inertial reference signal, a fast frequency support reference signal, a frequency control auxiliary service reference signal, a network support reference signal, and / or a charge / discharge reference signal.

[0029] According to one embodiment, at least one EIS reference signal superimposed on at least one control reference signal is adjusted to generate an interleaved signal with compensated current and voltage signals generated with a phase shift to reduce or eliminate power fluctuations caused by the injection of the EIS reference signal.

[0030] According to one embodiment, multiple power converters of the at least one power converter are grouped together, and harmonic currents caused by each individual power converter of the at least one power converter are compensated for by another power converter of the group.

[0031] According to one embodiment, the BMS includes sub-management units respectively corresponding to the battery cells in the battery module, and the management units acquire each of the response signals.

[0032] The present disclosure further relates to an apparatus for controlling at least one power converter, the apparatus comprising means for carrying out the above-described method.

[0033] The present disclosure further relates to a computer-readable storage medium comprising instructions that, when executed by a processor, cause the processor to perform the above-described method.

[0034] The present disclosure further relates to a system for controlling at least one power converter, the system including at least one power converter, at least one battery module, a battery management system (BMS), a battery energy storage system (BESS), and a controller including at least one processor configured to: generate at least one electrochemical impedance spectra (EIS) reference signal to be externally injected into a power grid, each of the at least one EIS reference signal having a frequency selected for EIS; superimpose the at least one EIS reference signal on at least one control reference signal to generate at least one superimposed reference signal; control each of the at least one power converter based on the at least one superimposed reference signal to respectively charge / discharge the at least one battery module; and calculate at least one EIS for each of the at least one battery module based on the at least one superimposed reference signal and the at least one response signal. A BMS is employed within the BESS, is communicatively coupled to the at least one battery module, and is configured to acquire at least one response signal respectively generated by the at least one battery module.

[0035] According to one embodiment, the power converter includes at least one AC / DC converter. According to one embodiment, the power grid is an AC grid.

[0036] According to one embodiment, the BESS comprises a battery configured to store power from a grid and configured to provide power to a power grid.

[0037] The following items refer to specific embodiments. 1. A method for controlling at least one power converter, comprising: generating at least one electrochemical impedance spectra (EIS) reference signal, each of the at least one EIS reference signal having a frequency selected for EIS; superimposing at least one EIS reference signal onto at least one respective control reference signal to generate at least one superimposed reference signal; controlling at least one power converter based on the at least one superimposed reference signal to respectively charge / discharge the at least one battery module; obtaining at least one response signal generated by each of the at least one battery module; calculating at least one EIS for each of the at least one battery module based on the at least one superimposed reference signal and the at least one response signal; A method comprising:

[0038] 2. At least one battery module each comprising at least one battery cell connected in series; the at least one response signal each includes a voltage signal generated across a respective one of the at least one battery cells; Charging / discharging the battery module based on the superimposed reference signal includes controlling a charge / discharge current; The method according to item 1.

[0039] 3. At least one battery module each includes at least one battery string connected in parallel; each battery string including at least one battery cell; the at least one response signal each including a current signal output from a respective one of the at least one battery string; Charging / discharging the battery module based on the superimposed reference signal includes controlling a charge / discharge voltage across at least one battery string; The method according to item 1.

[0040] 4. Generating at least one EIS reference signal includes pulse-width modulating the EIS reference signal; The method according to any one of items 1 to 3.

[0041] 5. The method of any one of items 1 to 3, wherein the number of the at least one battery module is an integer multiple of two, and the EIS reference signals for each of the two power converters are spaced apart by a phase shift of 180 degrees.

[0042] 6. The method of any one of items 1 to 3, wherein the number of the at least one battery module is N, an odd number greater than two, and the corresponding EIS reference signals are spaced apart by a phase shift of 360 degrees divided by N.

[0043] 7. The method of any one of items 1 to 3, further comprising using each of the at least one calculated EIS to derive status information regarding the state of health of each of the at least one battery module.

[0044] 8. Obtaining the at least one response signal is performed by a battery management system (BMS); The method according to any one of items 1 to 3.

[0045] 9. The method of any one of items 1 to 3, wherein at least one power converter each comprises power electronic components comprising silicon carbide.

[0046] 10. The method of any one of items 1 to 3, wherein the at least one control reference signal includes an inertial reference signal, a fast frequency support reference signal, a frequency control auxiliary service reference signal, a network support reference signal, and / or a charge / discharge reference signal.

[0047] 11. An apparatus for controlling at least one power converter, the apparatus comprising means for carrying out the method according to any one of items 1 to 10.

[0048] 12. A computer-readable storage medium comprising instructions that, when executed by a processor, cause the processor to perform the method of any one of items 1 to 10.

[0049] 13. A system for controlling at least one power converter, comprising: at least one power converter; at least one battery module; A control device comprising means for executing the method according to any one of items 1 to 10; A system comprising:

[0050] According to the present disclosure, the online EIS monitoring process in a BESS can be realized without equipment specially designed for EIS, thus reducing the cost of performing EIS.

[0051] It should be understood that the material set forth in this section is not intended to identify critical or important features of the embodiments of the present disclosure, nor should it be used to limit the scope of the present disclosure. Other features of the present disclosure will be readily apparent from the following specification.

[0052] BRIEF DESCRIPTION OF THE DRAWINGS The drawings illustratively illustrate embodiments, form a part of the specification, and together with the description of the specification are used to illustrate exemplary implementations of the embodiments. The illustrated embodiments are for illustrative purposes only and do not limit the scope of the claims. Throughout the drawings, like reference numerals designate similar, but not necessarily identical, elements. [Brief explanation of the drawings]

[0053] [Figure 1]1 is a flowchart illustrating a method for controlling at least one power converter in accordance with one or more examples of the present disclosure. [Figure 2A] FIG. 1 is a schematic diagram illustrating a method for controlling a DC / AC power converter in accordance with one or more examples of the present disclosure. [Figure 2B] FIG. 1 is a schematic diagram illustrating a method for controlling a DC / AC power converter in accordance with one or more examples of the present disclosure. [Figure 3A] FIG. 1 is a schematic diagram illustrating a method for controlling a DC / DC power converter in accordance with one or more examples of the present disclosure. [Figure 3B] FIG. 1 is a schematic diagram illustrating a method for controlling a DC / DC power converter in accordance with one or more examples of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram illustrating a method for controlling multiple DC / AC power converters in accordance with one or more examples of the present disclosure. [Figure 5] FIG. 1 is a schematic diagram illustrating a method for controlling multiple DC / DC power converters in accordance with one or more examples of the present disclosure. [Figure 6] 1 is a structural block diagram illustrating an apparatus for controlling at least one power converter, according to one or more examples of the present disclosure. [Figure 7] FIG. 1 is a structural block diagram illustrating an example system that may be used to implement one or more examples of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0054] Detailed Description of the Embodiments The present disclosure will be further described in detail below with reference to drawings and embodiments. It can be understood that the embodiments described herein do not limit the present disclosure, but are merely used to describe the relevant disclosure. It should be further noted that for ease of description, only parts related to the relevant disclosure are shown in the drawings.

[0055] It should be noted that the embodiments and features of the embodiments of the present disclosure can be combined with each other without contradiction. Where the number of elements is not specifically defined, one or more elements may be present unless otherwise explicitly indicated in the context. In addition, the number of steps or functional modules used in this disclosure does not limit either the order in which the steps are performed or the connection relationship between the functional modules, but is used merely to identify the steps or functional modules. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The term "based on" should be interpreted as "based at least in part on."

[0056] In the prior art, EIS is implemented by an offline monitoring process via equipment specifically designed for EIS, which poses both cost and design challenges when applied to a battery energy storage system (BESS) with a power converter.

[0057] Aiming at this problem, the present disclosure provides a method for controlling at least one power converter to realize an online EIS monitoring process in a BESS without equipment specifically designed for EIS.

[0058] 1 is a flowchart illustrating a method 100 for controlling at least one power converter according to one or more examples of the present disclosure. As shown in FIG. 1, method 100 may include steps S102-S110, which are described in further detail below.

[0059] In step S102, at least one electrochemical impedance spectra (EIS) reference signal may be generated, and the at least one EIS reference signal may each have a frequency selected for EIS.

[0060] The EIS reference signal may have a particular waveform, such as a sine wave, a square wave, a triangular wave, etc. The waveform of the EIS reference signal may be determined based on the actual application and may not be limited to the above examples.

[0061] The frequency selected for EIS may be determined based on the monitored characteristic or characteristics of interest for the battery. Because the impedance measured by EIS is closely related to various characteristics of the battery, such as the ohmic resistance of the electrolyte, the solid electrolyte interphase (SEI) capacitance, the electron transfer rate, and the diffusion process of species within the intercalation material of the battery, the frequency selected for EIS may correspond to the characteristics of interest based on the actual application, which may not be limited to the above examples. Each characteristic may correspond to a specific frequency or frequency range from about a few μHz to several MHz. For example, to monitor the ohmic resistance of the electrolyte, a frequency selected from the ultra-high frequency range may be employed.

[0062] In some embodiments, generating at least one EIS reference signal can include pulse-width modulating the EIS reference signal. In this manner, various frequencies of interest can be obtained through different modulations to achieve an online EIS monitoring method. The pulse-width modulation can be achieved by a pulse-width modulation (PWM) modulator or can be software-based (e.g., via a field programmable gate array (FPGA)), firmware-based (e.g., via a digital signal processor (DSP)), or hardware-based (e.g., via a digital signal processor (DSP)).

[0063] In some embodiments, the at least one power converter may each include power electronic components including silicon carbide (SiC). The power electronic components may include switching devices. SiC switching devices can switch at much higher frequencies than Si-based switching devices. Due to the higher switching frequency, SiC switching devices can achieve higher frequency bandwidths than Si-based switching devices. SiC switching devices can also provide cost benefits due to reduced filter size / cost. Additionally, the higher frequency bandwidth can help increase the accuracy of state-of-health monitoring and achieve state-of-health monitoring of more elements in the battery.

[0064] In step S104, the at least one EIS reference signal may be respectively superimposed on the at least one control reference signal to generate at least one superimposed reference signal.

[0065] In some embodiments, the at least one control reference signal may include, but is not limited to, an inertial reference signal, a fast frequency support reference signal, a frequency control auxiliary service reference signal, a network support reference signal, and / or a charge / discharge reference signal, etc. In this manner, the EIS reference signal may be flexibly superimposed onto any of a variety of reference signals to implement an online EIS monitoring method according to the present disclosure.

[0066] In step S106, the at least one power converter may be respectively controlled based on the at least one superimposed reference signal to respectively charge / discharge the at least one battery module.

[0067] In step S108, at least one response signal respectively generated by the at least one battery module may be obtained.

[0068] The response signal may include a voltage of the battery module when the power converter is controlling a charging current of the battery module, or may include a current of the battery module when the power converter is controlling a charging voltage of the battery module.

[0069] For example, the voltage or current of the battery module may be measured or obtained using a voltage / current sensor and an AD (Analog / Digital) or ADC (Analog to Digital Converter) module of the BMS. The voltage or current of the battery module may also be measured or obtained by additional measurement equipment that may be separate from the BMS.

[0070] In some embodiments, charging / discharging the battery modules based on the superimposed reference signal may include controlling the charge / discharge current. Accordingly, each of the at least one battery module may include at least one battery cell connected in series. Each of the at least one response signal may include a voltage signal generated across each of the at least one battery cell. Below, Figures 2A and 3A are described in connection with such embodiments.

[0071] In some embodiments, charging / discharging the battery modules based on the superimposed reference signal may include controlling a charge / discharge voltage across at least one battery string. Accordingly, each of the at least one battery module may include at least one battery string connected in parallel, each battery string including at least one battery cell. Each of the at least one response signal may include a current signal output from a respective one of the at least one battery strings. Below, Figures 2B and 3B are described in connection with such embodiments.

[0072] Setting the control current or voltage based on the structure of the battery module allows for adaptation of the superimposed reference signal to the battery module, so that the EIS reference signal used for online EIS monitoring can be injected via the charge / discharge of the battery module.

[0073] In some embodiments, if the number of at least one battery module is an integer multiple of two (e.g., 2, 4, 6, etc.), the EIS reference signals for each of the two power converters may be spaced apart by a phase shift of 180 degrees (i.e., π).

[0074] In some embodiments, if the number of at least one battery module is N, where N is an odd number greater than two (e.g., 3, 5, etc.), the corresponding EIS reference signals may be spaced apart by a phase shift of 360 degrees divided by N (i.e., 2π / N).

[0075] In this way, an interleaved signal with compensated current / voltage pulses may be generated by phase shifting, thereby reducing or eliminating power quality problems due to power fluctuations caused by the injection of the EIS reference signal. Figures 4 and 5 are described below with reference to such an embodiment.

[0076] In some embodiments, obtaining the at least one response signal may be performed by a battery management system (BMS). The BMS may be communicatively coupled to the at least one battery module, such that the at least one response signal generated by the at least one battery module may be obtained. Employing an intrinsic BMS within the BESS facilitates implementation of an online EIS monitoring method without introducing additional signal detection devices.

[0077] A Battery Energy Storage System (BESS) is commonly known as a combination of one or more power converters, a Battery Management System (BMS), and a battery module.

[0078] Typically, a BESS has one or more power converters connected between the power grid and the battery module, one of whose functions is to charge or discharge power between the power grid and the battery module.

[0079] A Battery Management System (BMS) can be a system connected to the battery cells of a battery module, which can communicate with a BESS or a power converter controller or a power converter system (PCS) in a power grid management system or any other higher-level controller. The functions of the BMS may include estimating the State of Charge (SOC) of the battery modules, monitoring the status of battery temperature, current, and voltage, and balancing the SOC of different battery modules.

[0080] In step S110, at least one EIS for each of the at least one battery module may be calculated based on the at least one superimposed reference signal and the at least one response signal.

[0081] In one example, when at least one battery module each includes at least one battery cell connected in series, the impedance of each of the at least one battery cell may be obtained by dividing at least one response signal (i.e., voltage signal) by a superimposed reference signal (i.e., current signal).

[0082] In one example, when at least one battery module each includes at least one battery string connected in parallel, the impedance of each of the at least one battery string may be obtained by dividing the respective superimposed reference signal (i.e., voltage signal) by the at least one response signal (i.e., current signal).

[0083] In some embodiments, after step S110, method 100 may further include step S112, in which state information regarding a state of health of each of the at least one battery module may be derived using each of the at least one calculated EIS. The state of health may include a state of charge (SOC) and / or a state of health (SOH) of the battery, etc.

[0084] According to the present disclosure, a method for controlling at least one power converter to realize an online EIS monitoring process in a BESS is provided without introducing equipment specifically designed for EIS. Through opportunities for charging / discharging the battery module, an EIS reference signal used for the online EIS monitoring process is injected from the power converter to the battery module, thereby enabling real-time monitoring of the battery module's health status. In this way, the online EIS monitoring process can be integrated into the power converter or power converter system (PCS) of the BESS, reducing both cost and design burdens.

[0085] 2A and 2B are schematic diagrams illustrating a method for controlling a DC / AC power converter according to one or more examples of the present disclosure. Except that the internal structures of the battery modules are different from each other and therefore the reference signals (i.e., the EIS reference signal, the control reference signal, and the response signal) are represented by either current signals or voltage signals, the principles of the methods for controlling the power converter are substantially the same.

[0086] As shown in FIG. 2A, the DC / AC power converter 210 receives a control reference signal I con The EIS reference signal I is superimposed on EIS A superimposed reference signal I sup to the battery module 212 to charge / discharge the battery module 212. The power converter 210 may be coupled to a utility side (e.g., a power grid).

[0087] As mentioned above, the EIS reference signal I EIS is pre-generated, and then the control reference signal I con The EIS reference signal I EIS may have a particular waveform (e.g., sine wave, square wave, triangular wave, etc.) and frequency selected for EIS. The frequency selected for EIS may be determined based on the characteristics to be monitored for the battery (e.g., ohmic resistance of the electrolyte, SEI capacitance, electron transfer rate, diffusion process of species within the battery's intercalation material, etc.). The control reference signal I con may include, for example, an inertial reference signal, a fast frequency support reference signal, a frequency control ancillary service reference signal, a network support reference signal, and / or a charge / discharge reference signal.

[0088] The battery module 212 may include a battery string consisting of first to third battery cells 212-1 to 212-3 connected in series. Although three battery cells are shown for illustrative purposes, fewer or more battery cells are possible based on the actual application.

[0089] a predetermined EIS reference signal I having a frequency selected for EIS to monitor the state of health of the battery module; EIS The injected superimposed reference signal I supIn response to V, the first to third battery cells 212-1 to 212-3 may generate respective response signals, namely, response signals V1 to V3, each of which may represent a voltage signal generated across the battery cell.

[0090] According to one embodiment, the response signals V1-V3 may be obtained by a battery management system (BMS) 214 communicatively coupled to the first to third battery cells 212-1-212-3. For example, the BMS 214 may include three sub-management units corresponding to the first to third battery cells 212-1-212-3, respectively, and each sub-management unit may obtain a respective one of the response signals V1-V3.

[0091] Alternatively, the response signals V1-V3 may be obtained by additional detection means communicatively coupled to the first to third battery cells 212-1-212-3. In the case shown in FIG. 2A, the detection means may include three voltage detectors, each connected in parallel to each of the first to third battery cells 212-1-212-3, to detect the voltages generated across the battery cells (i.e., the response signals V1-V3).

[0092] Subsequently, the impedance of each of the first to third battery cells 212-1 to 212-3 is calculated by, for example, superimposing each of the response signals V1 to V3 onto a superimposed reference signal I sup By dividing by the superimposed reference signal I sup and may be calculated based on each of the response signals V1 to V3.

[0093] Thus, the states of health of the first through third battery cells 212-1 through 212-3 may be derived from the calculated EIS. As an example, a threshold for determining the state of health (e.g., an impedance threshold for a characteristic of interest of the battery cells) may be preset to be compared to the calculated impedance to determine the state of health of the battery cells.

[0094] 2B illustrates a method for controlling a DC / AC power converter similar to the method of FIG. 2A. Nevertheless, as shown in FIG. 2B, the DC / AC power converter 220 is controlled by a control reference signal U con The EIS reference signal U is superimposed on EIS A superimposed reference signal U sup to the battery module 222 to charge / discharge the battery module 222. In other words, the reference signal is a voltage signal rather than a current signal. The power converter 220 may be coupled to a utility side (e.g., a power grid).

[0095] Similarly, the EIS reference signal U EIS is generated in advance, and then the control reference signal U con The EIS reference signal U EIS may have a particular waveform (e.g., sine wave, square wave, triangular wave, etc.) and frequency selected for EIS. The frequency selected for EIS may be determined based on the characteristics to be monitored for the battery (e.g., ohmic resistance of the electrolyte, SEI capacitance, electron transfer rate, diffusion process of species within the intercalation material of the battery, etc.). The control reference signal U con may include, for example, an inertial reference signal, a fast frequency support reference signal, a frequency control ancillary service reference signal, a network support reference signal, and / or a charge / discharge reference signal.

[0096] The battery module 222 may include three battery strings 222-1 to 222-3 connected in parallel, each including two battery cells. Although three battery strings and two battery cells in each string are shown for illustrative purposes, fewer or more battery strings and / or battery cells are possible based on the actual application.

[0097] a predetermined EIS reference signal U having a frequency selected for EIS to monitor the state of health of the battery module; EISThe injected superimposed reference signal U sup In response to the input signal, the first to third battery strings 222-1 to 222-3 can generate respective response signals, namely, response signals I1 to I3. Each of the response signals I1 to I3 can represent a current signal output from the battery string.

[0098] According to one embodiment, the response signals I1-I3 may be obtained by a battery management system (BMS) 224 communicatively coupled to the first to third battery strings 222-1-222-3. For example, the BMS 224 may include three sub-management units corresponding to the first to third battery strings 222-1-222-3, respectively, and each sub-management unit may obtain a respective one of the response signals I1-I3.

[0099] Alternatively, the response signals I1 to I3 may be obtained by additional detection means communicatively coupled to the first to third battery strings 222-1 to 222-3. In the case shown in FIG. 2B, the detection means may include three current detectors each connected in series to each of the first to third battery strings 222-1 to 222-3 to detect the current signals output from the battery strings.

[0100] Subsequently, the impedance of each of the first to third battery strings 222-1 to 222-3 is determined by, for example, the superimposed reference signal U sup is divided by each of the response signals I1 to I3 to obtain the superimposed reference signal U sup and may be calculated based on each of the response signals I1 to I3.

[0101] Thus, the states of health of the first through third battery strings 222-1 through 222-3 may be derived from the calculated EIS. As an example, a threshold for determining the state of health (e.g., an impedance threshold for a characteristic of interest of the battery string) may be preset for comparison with the calculated impedance to determine the state of health of the battery string.

[0102] 3A and 3B are schematic diagrams illustrating a method for controlling a DC / DC power converter according to one or more examples of the present disclosure. Except for the type of power converter, the principle of the method for controlling the power converter is substantially the same as that of FIG. 2A and 2B, and therefore, details regarding the same features will be omitted here.

[0103] As shown in FIG. 3A, the DC / DC power converter 310 receives a control reference signal I con The EIS reference signal I is superimposed on EIS A superimposed reference signal I sup to the battery module 312 to charge / discharge the battery module 312. The DC / DC power converter 310 may be coupled to a utility side (e.g., a power grid) via a DC / AC power converter 316.

[0104] The operation for acquiring the response signals V1 to V3 of the first to third battery cells 312-1 to 312-3 in the battery module 312 and the function of the BMS 314 (if any) are substantially the same as those in FIG. 2A. Therefore, the impedance of each of the first to third battery cells 312-1 to 312-3 is, for example, calculated by superimposing the response signals V1 to V3 on the superimposed reference signal I sup By dividing by the superimposed reference signal I sup and response signals V1 to V3, respectively. The states of health of the first to third battery cells 312-1 to 312-3 may then be derived from the calculated EIS.

[0105] As shown in FIG. 3B, the DC / DC power converter 320 is driven by a control reference signal U con The EIS reference signal U is superimposed on EIS A superimposed reference signal U sup to the battery module 322 to charge / discharge the battery module 322. The DC / DC power converter 320 may be coupled to a utility side (e.g., a power grid) via a DC / AC power converter 326.

[0106] The operation for acquiring the response signals I1 to I3 of the first to third battery strings 322-1 to 322-3 in the battery module 322 and the function of the BMS 324 (if any) are substantially the same as those in FIG. 2B. Therefore, the impedance of each of the first to third battery strings 322-1 to 322-3 is, for example, a function of the superimposed reference signal U sup is divided by each of the response signals I1 to I3 to obtain the superimposed reference signal U sup and response signals I1 to I3, respectively. The states of health of the first to third battery strings 322-1 to 322-3 may then be derived from the calculated EIS.

[0107] FIG. 4 is a schematic diagram illustrating a method for controlling multiple DC / AC power converters according to one or more examples of the present disclosure.

[0108] Due to the fact that the EIS reference signal must be injected externally into the power grid while the online EIS monitoring method is being performed, which may result in power quality issues, the present disclosure further provides improved EIS measurements by generating interleaved currents / voltages to mitigate or eliminate power quality issues during the performance of the online EIS monitoring method.

[0109] To measure the impedance of the battery cells in a battery module through online EIS monitoring, a power converter connected to a power grid charges or discharges the battery cells. The resulting changes in the power grid can be used to determine the power absorbed from or generated on the power grid. This can be achieved by controlling the power converter based on a superimposed reference signal.

[0110] The power flow between a power converter and the power grid may not be constant and may contain harmonics resulting from the control of the power converter based on a superimposed reference signal, including the EIS reference signal. Therefore, the EIS reference signal may be injected into the power grid. Harmonics resulting from the operation of the power converter can affect the performance of the AC power system (power grid). Harmonics can be minimized by controlling the power converter to compensate for the harmonics generated by other power converters in the system (BESS).

[0111] As shown in FIG. 4, multiple DC / AC power converters 410-1 to 410-n (where n is a natural number equal to or greater than 2) may be coupled in parallel to a utility side (eg, a power grid).

[0112] Each of the DC / AC power converters 410-1 to 410-n receives a control reference signal I con (For example, the illustrated I con1 and I con2 ) superimposed on the EIS reference signal I EIS (For example, the illustrated I EIS1 and I EIS2 ) including the superimposed reference signal I sup (For example, the illustrated I sup1 and I sup2) to each of the battery modules 412-1 to 412-n to charge / discharge the battery modules 412-1 to 412-n. Each of the battery modules 412-1 to 412-n may be configured similarly to the battery module 212 shown in FIG. 2A. Therefore, detailed internal structures of each of the battery modules 412-1 to 412-n will be omitted here.

[0113] Specifically, the power converter 410-1 receives a control reference signal I con1 The EIS reference signal I is superimposed on EIS1 A superimposed reference signal I sup1 to the battery module 412-1 to charge / discharge the battery module 412-1. Each of the remaining power converters 410-2 to 412-n may be configured to transmit an EIS reference signal I to generate the interleaved current. EIS1 ~I EISn may be configured similarly to power converter 410-1, except that the phase of

[0114] As mentioned above, the additional injection of harmonic currents / voltages into the EIS causes power fluctuations, which can have the drawback of affecting the DC capacitor life of the converter as well as impacting the utility. To this end, multiple power converters may be grouped together to address this issue.

[0115] According to one embodiment, two, four, six, etc. power converters may be grouped together. That is, the number of power converters (and therefore the number of corresponding battery modules) may be an integer multiple of two. In this case, the EIS reference signals for each two power converters may be spaced apart by a phase shift of 180 degrees (i.e., π). For example, if there are two power converters, namely, power converters 410-1 and 410-2, then the corresponding EIS reference signals I EIS1 and I EIS2 may have a phase inversion.

[0116] According to one embodiment, the number of power converters (and therefore the corresponding number of battery modules) may be N, an odd number greater than 2. In this case, the corresponding EIS reference signals may be spaced apart by a phase shift of 360 degrees divided by N (i.e., 2π / N). For example, if there are three power converters, namely, power converters 410-1, 410-2, and 410-3 (when n is 3), the corresponding EIS reference signals I EIS1 , I EIS2 , and I EIS3 may be spaced apart by a phase shift of 120 degrees.

[0117] Therefore, the harmonic currents caused by each individual power converter can be compensated by other power converters in the same group, so that interleaved currents with compensating current pulses can be generated to limit harmonic currents in order to address power quality issues, thus extending the life of the DC capacitors in the converters and limiting harmonic currents on the utility side.

[0118] The above-described embodiments for generating interleaved currents may refer to battery modules 412-1 through 412-n, each having at least one battery cell connected in series, similar to the embodiment shown in Figure 2A. Accordingly, the operations for obtaining the response signals of at least one battery cell in each of the battery modules and the functionality of the BMS (if any) are substantially the same as those in Figure 2A.

[0119] Therefore, the impedance of each of the at least one battery cell in each of the battery modules is calculated based on a respective superimposed reference signal (e.g., I sup1 , I sup2 The state of health of at least one battery cell in each of the battery modules may then be derived from the calculated EIS.

[0120] Alternatively, taking into account the internal structure of the battery modules 412-1 to 412-n, the interleaved current may be replaced with the interleaved voltage. That is, each of the battery modules 412-1 to 412-n may include at least one battery string connected in parallel, similar to the embodiment shown in FIG. 2B. Therefore, the operation for acquiring the response signal of at least one battery string in each of the battery modules and the function of the BMS (if any) are substantially the same as those in FIG. 2B.

[0121] Therefore, the impedance of each of the at least one battery string is determined by a respective superimposed reference signal (e.g., U sup1 , U sup2 ) and the respective response signals of the battery strings. A state of health of at least one battery string in each of the battery modules may then be derived from the calculated EIS.

[0122] FIG. 5 is a schematic diagram illustrating a method for controlling multiple DC / DC power converters in accordance with one or more examples of the present disclosure.

[0123] 5, multiple DC / DC power converters 510-1 to 510-n (where n is a natural number greater than or equal to 2) may be coupled in parallel to a DC bus 505. The DC bus 505 is coupled to a utility side (e.g., a power grid) via a DC / AC power converter 516.

[0124] In this embodiment, except that the type of power converter is modified as a DC / DC power converter, the principle of the method for controlling multiple power converters is substantially the same as that of FIG. 4, and therefore details regarding the same features will be omitted here.

[0125] FIG. 6 is a structural block diagram illustrating an apparatus 600 for controlling at least one power converter, according to one or more examples of the present disclosure.

[0126] As shown in FIG. 6 , the apparatus 600 may include a generating unit 602 configured to generate at least one EIS reference signal for EIS, where the at least one EIS reference signal each has a frequency selected for EIS; a superimposing unit 604 configured to superimpose the at least one EIS reference signal onto at least one control reference signal to generate at least one superimposed reference signal; a control unit 606 configured to control at least one power converter, respectively, based on the at least one superimposed reference signal to charge / discharge the at least one battery module, respectively; an acquiring unit 608 configured to acquire at least one response signal, respectively generated by the at least one battery module; and a computing unit 610 configured to calculate at least one EIS for each of the at least one battery module based on the at least one EIS reference signal and the at least one response signal.

[0127] The functions of each of the above-mentioned units 602 to 610 can correspond to steps S102 to S110 shown in FIG. 1, so similar details will be omitted here.

[0128] In some embodiments, the generating unit 602 may further include a pulse-width modulating (PWM) unit 6020 configured to pulse-width modulate the EIS reference signal.

[0129] In some embodiments, the apparatus 600 may further include a derivation unit 612 configured to derive state information regarding a state of health of each of the at least one battery module using each of the at least one calculated EIS. The function of the derivation unit 612 may correspond to step S112 shown in FIG. 1, and similar details will be omitted here.

[0130] FIG. 7 is a structural block diagram illustrating an example system 700 that may be used to implement one or more examples of the present disclosure.

[0131] 7, system 700 may include a power converter module 702 and a battery module 704. Power converter module 702 may include at least one power converter, and thus battery module 704 may include at least one battery module corresponding to the at least one power converter.

[0132] System 700 may further include a controller 706 for controlling the at least one power converter. In one embodiment, controller 706 may include means for performing the method described above, such as steps S102-S112 described in Figure 1. In one embodiment, device 706 may be implemented similarly to device 600 described in Figure 6, and similar details will therefore be omitted here.

[0133] According to the present disclosure, there is further provided a computer-readable storage medium comprising instructions that, when executed by a processor, cause the processor to perform the method described above.

[0134] According to the present disclosure there is further provided a computer program product which, when executed by a processor, performs the above-described method.

[0135] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, program segment, or portion of code, which includes one or more executable instructions for implementing a logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may also occur in a different order from the order marked in the accompanying drawings. For example, two blocks shown in succession may actually be executed substantially in parallel, or they may sometimes be executed in the reverse order, depending on the functionality involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that executes the function or operation, or by a combination of dedicated hardware and computer instructions.

[0136] The related units / modules described in the embodiments of the present disclosure may be implemented by software or hardware. The described modules may also be located in a processor, and the processor may be described as including, for example, a generating module, a superimposing module, a control module, an acquiring module, and a calculating module. The names of these modules do not limit the modules themselves in a particular situation.

[0137] The foregoing description merely describes preferred embodiments of the present disclosure and the applied technical principles. Those skilled in the art should understand that the scope of the present disclosure included in the embodiments of the present disclosure is not limited to the technical solution formed by a specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the above-mentioned inventive concept. For example, (but not limited to) technical solutions formed by replacing the above-mentioned features with technical features having similar functions in the technical features disclosed in the embodiments of the present disclosure also fall within the scope of the present disclosure.

Claims

1. 1. A method for controlling at least one power converter coupled to a power grid, the method comprising: generating at least one electrochemical impedance spectra (EIS) reference signal to be externally injected into the power grid, the at least one EIS reference signal each having a frequency selected for EIS; superimposing the at least one EIS reference signal onto at least one control reference signal to generate at least one superimposed reference signal; controlling the at least one power converter based on the at least one superimposed reference signal to respectively charge / discharge at least one battery module; obtaining at least one response signal generated by each of the at least one battery module; calculating at least one EIS for each of the at least one battery modules based on the at least one superimposed reference signal and the at least one response signal; Including, a battery management system (BMS) employed within a battery energy storage system (BESS) communicatively coupled to the at least one battery module such that the at least one response signal generated by the at least one battery module is acquired; method.

2. each of the at least one battery module comprises at least two battery cells connected in series; the at least one response signal each including a voltage signal generated across a respective one of the at least one battery cells; The charging / discharging of the battery module based on the superimposed reference signal includes controlling a charging / discharging current. The method of claim 1.

3. each of the at least one battery module includes at least two battery strings connected in parallel; each battery string including at least one battery cell; each of the at least one response signal includes a current signal output from a respective one of the at least one battery strings; the charging / discharging of the battery module based on the superimposed reference signal includes controlling a charge / discharge voltage across the at least one battery string. The method of claim 1.

4. generating the at least one EIS reference signal includes pulse-width modulating the EIS reference signal. The method of claim 1.

5. 10. The method of claim 1, wherein the number of the at least one battery module is an integer multiple of two, and the EIS reference signals for each of two power converters are spaced apart by a 180 degree phase shift.

6. 10. The method of claim 1, wherein the number of the at least one battery module is N, an odd number greater than two, and the EIS reference signals corresponding to each of the power converters are spaced apart by a phase shift of 360 degrees divided by N.

7. 10. The method of claim 1, further comprising: using each of the at least one calculated EIS to derive state information regarding a state of health of each of the at least one battery module.

8. the obtaining of the at least one response signal is performed by a battery management system (BMS). The method of claim 1.

9. The method of claim 1 , wherein the at least one power converter each comprises power electronic components comprising silicon carbide.

10. The method of claim 1 , wherein the at least one control reference signal comprises an inertial reference signal, a fast frequency support reference signal, a frequency control ancillary service reference signal, a network support reference signal, and / or a charge / discharge reference signal.

11. 10. The method of claim 1, wherein the at least one EIS reference signal superimposed on at least one control reference signal is adjusted to generate an interleaved signal having compensated current and voltage signals generated with a phase shift to reduce or eliminate power fluctuations caused by the injection of the EIS reference signal.

12. 2. The method of claim 1, wherein multiple power converters of the at least one power converter are grouped together, and harmonic currents caused by each individual power converter of the at least one power converter are compensated for by another power converter of the group.

13. The method of claim 1 , wherein the BMS includes sub-management units corresponding to respective battery cells in a battery module, and the sub-management units acquire the respective response signals.

14. Apparatus for controlling at least one power converter, said apparatus comprising means for carrying out the method according to any one of claims 1 to 13.

15. A computer-readable storage medium comprising instructions which, when executed by a processor, cause the processor to perform the method of any one of claims 1 to 13.

16. 1. A system for controlling at least one power converter, comprising: the at least one power converter; at least one battery module; Battery management system (BMS), battery energy storage systems (BESSs), and generating at least one electrochemical impedance spectra (EIS) reference signal to be externally injected into the power grid, the at least one EIS reference signal each having a frequency selected for EIS; superimposing the at least one EIS reference signal onto at least one control reference signal to generate at least one superimposed reference signal; controlling the at least one power converter based on the at least one superimposed reference signal to respectively charge / discharge at least one battery module; calculating at least one EIS for each of the at least one battery modules based on the at least one superimposed reference signal and the at least one response signal; a control device comprising at least one processor configured to perform Equipped with the BMS is employed within the BESS, communicatively coupled to the at least one battery module, and configured to acquire at least one response signal respectively generated by the at least one battery module. system.

17. The system of claim 16 , wherein the power converter comprises at least one AC / DC converter.

18. 17. The system of claim 16, wherein the power grid is an AC grid.

19. 19. The system of claim 16, wherein the BESS comprises a battery configured to store power from the power grid and configured to supply power to the power grid.

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