A battery management unit, energy storage system electrochemical impedance detection device and method

Abstract

The application discloses a battery management unit, an energy storage system electrochemical impedance detection device and method, and relates to the technical field of electrochemical impedance detection. The battery management unit is composed of an energy exchange device, a microcontroller, an analog front end and a first sampling resistor. The energy exchange device comprises a capacitor, an inductor, a first MOS tube, a second MOS tube and a driving chip. The energy storage system electrochemical impedance detection device is composed of a power supply, a battery cluster management unit, a pre-charging circuit, a second sampling resistor and at least one battery management unit. By controlling the energy exchange device, the on-off state of the first MOS tube and the second MOS tube is alternately switched in each excitation current period, and alternating excitation is performed on the battery module. Therefore, the single cell electrochemical impedance detection without external power supply and suitable for floating charging conditions can be realized.

Description

Technical Field

[0001] This invention relates to the field of electrochemical impedance spectroscopy, and more particularly to an electrochemical impedance spectroscopy device and method for a battery management unit and an energy storage system. Background Technology

[0002] Battery state assessment methods based on electrochemical impedance spectroscopy (EIS) technology can effectively characterize battery health, state of charge, and aging by injecting a small AC excitation signal into the battery and analyzing its impedance response.

[0003] However, existing EIS testing technologies still face several challenges in practical engineering applications, especially in scenarios such as data center energy storage where batteries operate under float charging conditions for extended periods. First, current testing solutions typically only acquire overall electrochemical impedance information of the battery system, obtaining system-level impedance spectrum data by analyzing the AC response of the battery pack's total voltage and current. They cannot achieve refined impedance measurements at the individual cell or module level. Second, existing impedance testing methods lack independent active excitation sources; the generation of their excitation signals relies on external power modules, resulting in low integration of the testing device and strong dependence on external equipment. Third, in applications such as data center energy storage, batteries operate under float charging conditions for extended periods. Float charging refers to a state where, in backup power applications, the battery is always connected in parallel with the charging device, which continuously provides a small supplementary current to maintain its full charge. Under these conditions, the battery cannot interrupt the charging circuit, nor can it discharge normally to the outside world. This makes it difficult for traditional detection methods that rely on high current excitation injection or require changes in the battery's charging and discharging state to start normally or work stably under these conditions. The enable control of the excitation source cannot be effectively executed, making it almost impossible to implement existing EIS technology in this type of scenario. Summary of the Invention

[0004] To address the aforementioned technical problems, embodiments of the present invention provide a battery management unit, an electrochemical impedance spectroscopy device and method for an energy storage system, which solves the technical problem that existing electrochemical impedance spectroscopy methods cannot perform cell electrochemical impedance spectroscopy without relying on an external power source.

[0005] A first aspect of this invention provides a battery management unit, including an energy exchange device, a microcontroller, an analog front-end, and a first sampling resistor. The energy exchange device includes a capacitor, an inductor, a first MOSFET, a second MOSFET, and a driver chip. The analog front-end includes at least a first analog input terminal and a second analog input terminal. The first terminal of the capacitor and the first terminal of the inductor are both used to connect to the positive terminal of the battery module formed by connecting multiple battery cells in series. The second terminal of the capacitor is connected to the first terminal of the first MOSFET. The second terminal of the inductor and the first terminal of the second MOSFET are both connected to the second terminal of the first MOSFET. The second terminal of the second MOSFET and the first analog input terminal are both connected to the first terminal of the first sampling resistor. The second terminal of the first sampling resistor is used to connect to the negative terminal of the battery module formed by connecting multiple battery cells in series. The second terminal of the first sampling resistor is also connected to the second analog input terminal. The driver chip includes a first control signal output pin and a second control signal output pin. The first pin is connected to the third terminal of the first MOSFET, and the second pin is connected to the third terminal of the second MOSFET. The microcontroller is used to output control signals to the driver chip, thereby driving the driver chip's first control signal output pin and second control signal output pin to output closed or open signals. Furthermore, it also includes: The microcontroller communicates with the analog front end and is also used to receive voltage and current data sent by the analog front end.

[0006] A second aspect of the present invention provides an electrochemical impedance spectroscopy device for an energy storage system, comprising a power supply, a battery cluster management unit, a precharge circuit, a second sampling resistor, and at least one battery management unit as claimed in this claim, wherein... The first terminal of the power supply and the first terminal of the precharge circuit are used to connect to the positive terminal of the battery pack. The second terminal of the precharge circuit is used to connect to the positive terminal of the load. The second terminal of the power supply is connected to the battery cluster management unit. The battery cluster management unit is connected to the battery management unit. The first terminal of the second sampling resistor is used to connect to the positive terminal of the battery pack. The second terminal of the second sampling resistor is used to connect to the negative terminal of the load. Power supply, used to power the battery cluster management unit; The battery management unit is used to send an electrochemical impedance detection signal to the battery management unit, and to obtain the electrochemical impedance value based on the current data and voltage data sent by the battery management unit.

[0007] Furthermore, the pre-charge circuit includes at least a discharge contactor, a charging contactor, a pre-charge contactor, a discharge diode, and a pre-charge resistor; The first end of the discharge contactor and the first end of the precharge contactor are used to connect to the positive terminal of the battery pack. The second end of the discharge contactor is connected to the second end of the charging contactor. The second end of the charging contactor is used to connect to the load. The second end of the precharge contactor is connected to the first end of the precharge resistor, and the second end of the precharge resistor is used to connect to the load.

[0008] Furthermore, the precharge circuit can also be replaced by a precharge control module, which includes an integrated circuit or component with precharge control function.

[0009] A third aspect of the present invention provides a method for detecting electrochemical impedance spectroscopy in an energy storage system, comprising: The energy exchange device controls the alternating excitation of the battery module by alternately switching the conduction states of the first MOSFET and the second MOSFET during each excitation current cycle. During each excitation current cycle, the current data flowing through the battery module and the voltage data across each cell in the battery module are collected by the analog front end. For each cell, multiple current and voltage data are converted in the frequency domain to obtain the complex vectors of current and voltage for each cell. The electrochemical impedance value of the battery cell is obtained based on the complex vectors of current and voltage.

[0010] Furthermore, the energy exchange device controls the alternating excitation of the battery module by alternately switching the conduction states of the first MOSFET and the second MOSFET during each excitation current cycle, including: During each excitation current cycle, the first MOSFET is turned off, and the second MOSFET is turned on for a first preset time before the first MOSFET is turned off again, and the second MOSFET is turned off, so that the inductor charges the capacitor. When the current flowing through the inductor is zero, the first MOSFET is closed and the second MOSFET is opened to allow the capacitor to discharge into the inductor. When the current collected during the discharge of the capacitor to the inductor reaches the preset current threshold, the first MOSFET and the second MOSFET are both turned off, so that the inductor charges the battery module.

[0011] Furthermore, after the inductor charges the battery module, it also includes: Charging stops when the current from the inductor charging the battery module is zero.

[0012] Furthermore, based on the complex vectors of current and voltage, the electrochemical impedance value of the battery cell is obtained, including: Calculate the ratio of the complex current vector to the complex voltage vector, and obtain the ratio result; The imaginary part of the ratio result is determined to be the electrochemical impedance value of the battery cell.

[0013] Furthermore, a fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method of the third aspect of this embodiment.

[0014] Compared with the prior art, the beneficial effects of the embodiments of the present invention are at least one of the following: The battery management unit includes an energy exchange device, a microcontroller, an analog front-end, and a first sampling resistor. The energy exchange device includes a capacitor, an inductor, a first MOSFET, a second MOSFET, and a driver chip. The analog front-end includes at least a first analog input terminal and a second analog input terminal. The first terminals of the capacitor and the inductor are both connected to the positive terminal of the battery module. The second terminal of the capacitor is connected to the first terminal of the first MOSFET. The second terminal of the inductor and the first terminal of the second MOSFET are both connected to the second terminal of the first MOSFET. The second terminal of the second MOSFET and the first analog input terminal are both connected to the first terminal of the first sampling resistor. The second terminal of the first sampling resistor is connected to the negative terminal of the battery module and the second analog input terminal. The first and second control signal output pins of the driver chip are respectively connected to the third terminals of the first and second MOSFETs. The microcontroller outputs control signals to the driver chip to drive the first and second control signal output pins of the driver chip to output closed or open signals. This battery management unit enables single-cell electrochemical impedance detection without an external power supply, suitable for float charging conditions. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the circuit structure of the battery management unit in one embodiment of the present invention; Figure 2 This is a structural diagram of an electrochemical impedance spectroscopy device for an energy storage system according to one embodiment of the present invention; Figure 3 This is a flowchart of an electrochemical impedance spectroscopy method for an energy storage system according to one embodiment of the present invention; Figure 4 This is a schematic diagram of the excitation period current waveform of the electrochemical impedance detection method for an energy storage system in one embodiment of the present invention. The reference numerals in the accompanying drawings are as follows: 11, Energy exchange device; 12, Microcontroller; 13, Analog front end; 14, First sampling resistor; 111, Capacitor; 112, Inductor; 113, First MOSFET; 114, Second MOSFET; 115, Driver chip; 131, First analog input terminal; 132, Second analog input terminal; 1151, First control signal output pin; 1152, Second control signal output pin; 100, Fourth resistor; 200, Battery cluster management unit; 300, Precharge circuit; 400, Second sampling resistor; 500, Battery management unit; 301, Discharge contactor; 302, Charging contactor; 303, Precharge contactor; 304, Precharge resistor; 305, Discharge diode. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0018] One embodiment of the present invention provides a battery management unit; for details, please refer to [link to specific documentation]. Figure 1 , Figure 1 The diagram shows the overall structure of a battery management unit in one embodiment of the present invention, including an energy exchange device 11, a microcontroller 12, an analog front-end 13, and a first sampling resistor 14. The energy exchange device 11 includes a capacitor 111, an inductor 112, a first MOS (Metal-Oxide-Semiconductor Field-Effect Transistor) 113, a second MOS 114, and a driver chip 115. The analog front-end 13 includes at least a first analog input terminal 131 and a second analog input terminal 132. In this embodiment, the battery management unit 500 (BMU) manages a specific battery module, which is composed of multiple cells connected in series. The battery management unit 500 monitors the voltage, temperature, and other operating parameters of each cell within the battery module and sends voltage and temperature data reports to the higher-level management unit.

[0019] The first end of capacitor 111 and the first end of inductor 112 are both used to connect to the positive terminal of the battery module formed by connecting multiple cells in series. The second end of capacitor 111 is connected to the first end of first MOSFET 113. The second end of inductor 112 and the first end of second MOSFET 114 are both connected to the second end of first MOSFET 113. The second end of second MOSFET 114 and the first analog input terminal 131 are both connected to the first end of first sampling resistor 14. The second end of first sampling resistor 14 is used to connect to the negative terminal of the battery module formed by connecting multiple cells in series. The second end of first sampling resistor 14 is also connected to second analog input terminal 132. The driver chip 115 includes a first control signal output pin 1151 and a second control signal output pin 1152. The first pin is connected to the third terminal of the first MOSFET 113, and the second pin is connected to the third terminal of the second MOSFET 114. The microcontroller 12 is used to output control signals to the driver chip 115 to drive the first control signal output pin 1151 and the second control signal output pin 1152 of the driver chip 115 to output closed or open signals.

[0020] In this embodiment, the first end of capacitor 111 and the first end of inductor 112 are both connected to the positive terminal of the battery module formed by connecting multiple battery cells in series. That is, in application, the common connection terminal of capacitor 111 and inductor 112 is connected to the positive terminal of the battery module. The second end of capacitor 111 is connected to the first end of first MOSFET 113. The second end of inductor 112 and the first end of second MOSFET 114 are both connected to the second end of first MOSFET 113. In other words, first MOSFET 113 and second MOSFET 114 are connected in series, and the second end of inductor 112 is connected between the second end of first MOSFET 113 and the first end of second MOSFET 114. The second end of second MOSFET 114 and the first analog input terminal 131 are both connected to the first end of first sampling resistor 14. The second end of first sampling resistor 14 is used to connect to the negative terminal of the battery module formed by connecting multiple battery cells in series, and the second end of first sampling resistor 14 is also connected to second analog input terminal 132. With the above connection method, the first sampling resistor 14 is connected in series in the main charging and discharging circuit between the battery module and the energy exchange device 11. The current flowing through the battery module will flow through the first sampling resistor 14 and form a voltage drop across it. The analog front end 13 collects the differential voltage signal across the first sampling resistor 14 through its first analog input terminal 131 and second analog input terminal 132. Then, the battery cluster management unit 200 calculates the current value flowing through the battery module according to Ohm's law.

[0021] It should be noted that both the first MOSFET 113 and the second MOSFET 114 are metal-oxide-semiconductor field-effect transistors (MOSFETs). The first terminal of the first MOSFET 113 is the drain, the second terminal is the source, and the third terminal is the gate; the first terminal of the second MOSFET 114 is the drain, the second terminal is the source, and the third terminal is the gate. Of course, the definitions of the first, second, and third terminals can be adjusted according to the type of MOSFET. For example, in a P-channel MOSFET, the connection relationship between the source and drain is reversed compared to an N-channel MOSFET. Those skilled in the art can make corresponding adjustments based on the actual type of MOSFET selected, as long as the same switching control function is achieved.

[0022] In this embodiment, the driver chip 115 is an isolated driver integrated circuit used to convert the low-voltage control signal output by the microcontroller 12 into a drive level that can drive the MOSFETs to turn on or off. The driver chip 115 includes a first control signal output pin 1151 and a second control signal output pin 1152. The first control signal output pin 1151 is connected to the gate of the first MOSFET 113, and the second control signal output pin 1152 is connected to the gate of the second MOSFET 114Q2. After receiving the control signal output by the microcontroller 12, the driver chip 115 outputs corresponding drive voltages through the first control signal output pin 1151 and the second control signal output pin 1152, respectively, to control the gate voltages of the first MOSFET 113 and the second MOSFET 114, thereby controlling their on or off states.

[0023] In some embodiments, it also includes: The microcontroller 12 is communicatively connected to the analog front-end 13, and the microcontroller 12 is also used to receive voltage and current data sent by the analog front-end 13.

[0024] In this embodiment, the microcontroller 12 is communicatively connected to the analog front-end 13 to receive voltage and current data sent by the analog front-end 13. For example, the microcontroller 12 establishes a bidirectional communication connection with the analog front-end 13 via an SPI bus. SPI (Serial Peripheral Interface) is a high-speed, full-duplex, synchronous communication bus suitable for short-distance, high-speed data transmission between chips. On the one hand, the microcontroller 12 sends configuration commands to the analog front-end 13 via the SPI bus, such as setting parameters like sampling channel, sampling rate, and gain; on the other hand, the microcontroller 12 reads the current and voltage data collected and converted by the analog front-end 13 via the SPI bus. It should be noted that this embodiment does not limit the specific communication method between the microcontroller 12 and the analog front-end 13. In other embodiments, the microcontroller 12 and the analog front-end 13 can also use an I2C bus, CAN bus, or other communication interfaces for data transmission. Any interface method that can achieve bidirectional communication between the microcontroller 12 and the analog front-end 13 can be used instead.

[0025] In some embodiments, such as Figure 2As shown, this embodiment of the invention provides an electrochemical impedance spectroscopy device for an energy storage system, including a power supply 100, a battery cluster management unit 200, a precharge circuit 300, a second sampling resistor 400, and at least one battery management unit 500 as described in the above embodiment. The battery cluster management unit 200 (BCMU) is responsible for managing a battery cluster, which is composed of multiple battery modules connected in series. Its functions include receiving data reported by each battery management unit 500, executing cluster-level protection strategies, and communicating with the upper-level system. The precharge circuit 300 is a circuit structure used to precharge the capacitor 111 on the load side through a current-limiting element when the battery pack is connected to a load, in order to avoid generating excessive inrush current when directly connected.

[0026] In this embodiment, the first terminal of the power supply 100 and the first terminal of the precharge circuit 300 are connected to the positive terminal of the battery pack. The power supply 100 is a power conversion module that draws power from the battery pack and is used to provide operating power to the battery cluster management unit 200. The second terminal of the power supply 100 is connected to the battery cluster management unit 200. The second terminal of the precharge circuit 300 is connected to the positive terminal of a load, which may include the DC bus of the energy storage system, an inverter, or other electrical equipment. The power supply 100 is used to supply power to the battery cluster management unit 200. The battery cluster management unit 200 is communicatively connected to the battery management unit 500 and is used to send an electrochemical impedance detection signal to the battery management unit 500, and to obtain the electrochemical impedance value based on the current data and voltage data sent by the battery management unit 500. In this embodiment, the battery cluster management unit 200 and the battery management unit 500 are communicatively connected via a CAN bus. Of course, in other embodiments, the BCMU and BMU may also use an RS485 bus, Ethernet, or other communication methods.

[0027] In this embodiment, one end of the second sampling resistor 400 is connected to the positive terminal of the battery pack, and the other end is connected to the negative terminal of the load. The second sampling resistor 400 is also connected to the battery cluster management unit communication 200.

[0028] In some embodiments, the precharge circuit 300 includes at least a discharge contactor 301, a charging contactor 302, a precharge contactor 303, a discharge diode 305, and a precharge resistor 304; The first end of the discharge contactor 301 and the first end of the precharge contactor 303 are used to connect to the positive terminal of the battery pack. The second end of the discharge contactor 301 is connected to the second end of the charging contactor 302. The second end of the charging contactor 302 is used to connect to the load. The second end of the precharge contactor 303 is connected to the first end of the precharge resistor 304, and the second end of the precharge resistor 304 is used to connect to the load.

[0029] In this embodiment, as Figure 2 As shown, the pre-charge circuit 300 in the electrochemical impedance spectroscopy device of the energy storage system includes at least a discharge contactor 301, a charging contactor 302, a pre-charge contactor 303, a discharge diode 305, and a pre-charge resistor 304. The discharge contactor 301 is used to connect or disconnect the main circuit during discharge, the charging contactor 302 is used to connect or disconnect the main circuit during charging, and the pre-charge contactor 303 is used to connect the pre-charge branch during the pre-charge stage. The specific connection method of the pre-charge circuit 300 is as follows: the first end of the discharge contactor 301 and the first end of the pre-charge contactor 303 are connected to the positive terminal of the battery pack. The second end of the discharge contactor 301 is connected to the second end of the charging contactor 302, and the second end of the charging contactor 302 is used to connect to the load; that is, the discharge contactor 301 and the charging contactor 302 are connected in series and then connected to the positive terminal of the load. In this embodiment, the second end of the pre-charge contactor 303 is connected to the first end of the pre-charge resistor 304, and the second end of the pre-charge resistor 304 is connected to the load. The circuit formed by the series connection of pre-charge contactor 303 and pre-charge resistor 304 is connected in parallel with the main circuit. Discharge diode 305 is connected in parallel with charging contactor 302, serving to prevent reverse current flow and provide freewheeling. When charging contactor 302 is open, the reverse electromotive force generated by the inductive element on the load side can form a freewheeling path through discharge diode 305, protecting the contactor and other circuit components. It should be noted that this main circuit refers to the discharge circuit where the battery pack outputs electrical energy to the external load. When the system is powered on, the battery cluster management unit 200 first controls the pre-charge contactor 303 to close, and the battery pack current charges the load side through pre-charge resistor 304. After the load side is charged to near the battery pack voltage, it then controls either discharge contactor 301 or charging contactor 302 to close, and finally opens pre-charge contactor 303, completing the power-on process.

[0030] In some embodiments, the precharge circuit 300 may also be replaced by a precharge control module, which includes an integrated circuit or component having a precharge control function.

[0031] In this embodiment, the precharge circuit 300 can also be replaced by a precharge control module, which includes an integrated circuit or component with precharge control function. For example, the precharge control module can be an intelligent precharge chip integrating a precharge resistor 304 and a precharge switch, or it can be a precharge control circuit composed of discrete components. Any circuit or module that can perform precharge on the load side upon power-up can replace the precharge circuit 300 in this embodiment.

[0032] Another embodiment of the present invention provides a method for detecting the electrochemical impedance spectroscopy of an energy storage system. Please refer to [link to relevant documentation]. Figure 3 , Figure 3The diagram shows a flowchart of an electrochemical impedance spectroscopy (EIS) detection method for an energy storage system according to one embodiment of the present invention. The method is implemented using an EIS detection device for an energy storage system as described in any of the above embodiments, and includes the following steps S1 to S4: S1. The energy exchange device controls the alternating excitation of the battery module by alternately switching the conduction states of the first MOSFET and the second MOSFET during each excitation current cycle.

[0033] In this embodiment, after the battery management unit and battery cluster management unit are powered on, the data center battery is in standby mode. Therefore, the system returns power to charge the battery. After it is fully charged, the charging contactor disconnects. Since the positive and negative terminals of the external load are in a floating charge state due to the continuous charging voltage, they cannot be discharged externally as an excitation source. The battery pack is also in a fully charged state and cannot be used as an excitation source for charging. At this time, the battery cluster management unit sends a command through communication control signals to enable the battery management unit to start the cell electrochemical internal resistance detection.

[0034] The microcontroller in the battery management unit controls the conduction states of the first and second MOSFETs via a driver chip, causing the energy exchange device to alternately switch the conduction states of the first and second MOSFETs in each excitation current cycle, thereby generating an alternating excitation current in the main circuit of the battery module. The excitation current cycle referred to here is one complete cycle of the alternating excitation current waveform, as shown in the figure below. Figure 4 As shown.

[0035] This embodiment does not limit the specific duration of the excitation current cycle. This duration can be set according to the electrochemical impedance frequency response characteristics of the battery cell under test. For example, it can be set to any value between 1ms and 100ms, corresponding to an excitation frequency of 10Hz to 1000Hz. Of course, in other embodiments, this duration can also be set to other values ​​according to specific testing requirements.

[0036] In some embodiments, the energy exchange device performs alternating excitation to the battery module by alternately switching the conduction states of the first MOSFET and the second MOSFET during each excitation current cycle, including: During each excitation current cycle, the first MOSFET is turned off, and the second MOSFET is turned on for a first preset time before the first MOSFET is turned off again, and the second MOSFET is turned off, so that the inductor charges the capacitor. When the current flowing through the inductor is zero, the first MOSFET is closed and the second MOSFET is opened to allow the capacitor to discharge into the inductor. When the current collected during the discharge of the capacitor to the inductor reaches the preset current threshold, the first MOSFET and the second MOSFET are both turned off, so that the inductor charges the battery module.

[0037] In this embodiment, during each excitation current cycle, the microcontroller controls the first MOSFET to turn off and the second MOSFET to turn on for a first preset time via the driver chip. At this point, the current path is: positive terminal of the battery module, inductor, second MOSFET, first sampling resistor, and negative terminal of the battery module. This current path is a forward excitation current path. The total voltage of the battery module is determined by the inductor, the current at this point, and the first preset closing time of the second MOSFET, expressed as: In the formula, This is the total voltage of the battery module. This is the inductance value. This is the excitation current of the current path. This is the first preset time.

[0038] After a first preset time, the microcontroller controls the first MOSFET to remain off while simultaneously controlling the second MOSFET to turn off. At this time, the inductor stores magnetic field energy. Based on the characteristic that inductor current cannot change abruptly, the inductor generates an induced electromotive force. Current flows through the body diode of the first MOSFET to charge the capacitor, converting the magnetic field energy in the inductor into the electric field energy in the capacitor. The energy formula is: In the formula, For energy, This is the inductance value. The current flowing through the inductor, This is the capacitance value. Charge the capacitor to the maximum permissible voltage, and When all the energy in the inductor has been released, the current drops to 0. The time it takes for the inductor to release all its energy is... .

[0039] When the inductor passes through After the stored energy is released into the capacitor, the microcontroller, via the driver chip, controls the first MOSFET to close while the second MOSFET remains open. At this point, the electric field energy stored in the capacitor discharges through the first MOSFET to the inductor, converting the electric field energy in the capacitor into magnetic field energy in the inductor. This phase lasts for [duration missing]. It should be noted that, and The expression is: In the formula, This is the inductance value. This is the capacitance value.

[0040] In some embodiments, after the inductor charges the battery module, the method further includes: Charging stops when the current from the inductor charging the battery module is detected to be 0.

[0041] In this embodiment, when the analog front-end detects that the current discharging from the capacitor to the inductor reaches a preset current threshold, the microcontroller controls the first and second MOSFETs to disconnect via the driver chip. At this time, the magnetic field energy in the inductor needs to be released via freewheeling, and the induced electromotive force generated by the inductor causes current to flow to the battery module. This current direction is opposite to the forward excitation current direction, i.e., it is the reverse excitation current, which reverse-charges the battery. When the energy in the inductor is completely released, the reverse excitation current drops to 0, and a complete excitation current cycle ends. Repeating the above process yields multiple excitation current cycles.

[0042] S2. During each excitation current cycle, the current data flowing through the battery module and the voltage data at both ends of each cell in the battery module are collected by the analog front end.

[0043] In this embodiment, during each excitation current cycle, the analog front-end acquires the differential voltage signal across the first sampling resistor through its first and second analog input terminals, and calculates the current data flowing through the battery module based on the resistance value of the first sampling resistor. In this embodiment, the analog front-end can also acquire the voltage data across each individual battery cell through its multiple cell voltage sampling channels. The number of cell voltage sampling channels is determined by the number of cells connected in series in the battery module, with the positive and negative terminals of each cell connected to their respective sampling channels on the analog front-end. When acquiring current and voltage data, the analog front-end triggers synchronous sampling based on the same clock source to ensure that the current and voltage data are strictly time-corresponding, thereby guaranteeing the accuracy of subsequent impedance calculations.

[0044] S3. Perform frequency domain transformation on the multiple current and voltage data corresponding to each cell to obtain the complex current vector and complex voltage vector of each cell.

[0045] In this embodiment, the battery cluster management unit performs frequency domain transformation on the current and voltage data of each cell under each excitation cycle to obtain the corresponding complex current vector and complex voltage vector. The expression for the complex current vector is as follows: In the formula, It is a complex vector of current. Let be the real part of the complex vector of current. represents the imaginary part coefficient of the complex vector of current.

[0046] The expression for the complex voltage vector is: In the formula, It is a voltage complex vector. Let be the real part of the voltage complex vector. These are the imaginary coefficients of the voltage complex vector.

[0047] S4. Based on the complex vectors of current and voltage, the electrochemical impedance value of the battery cell is obtained.

[0048] In this embodiment, according to Ohm's law for complex numbers, the electrochemical impedance is equal to the complex vector of voltage divided by the complex vector of current. Since both the complex vector of voltage and the complex vector of current are complex numbers, the result obtained after the operation is also a complex number, including both real and imaginary parts.

[0049] In some embodiments, the electrochemical impedance value of the battery cell is obtained based on the complex vector of current and the complex vector of voltage, including: Calculate the ratio of the complex current vector to the complex voltage vector, and obtain the ratio result; The imaginary part of the ratio result is determined to be the electrochemical impedance value of the battery cell.

[0050] In this embodiment, the complex impedance of each cell is calculated based on the complex current vector and the complex voltage vector of each cell. The expression for the complex impedance is as follows: In the formula, It is a complex vector of current. It is a complex voltage vector.

[0051] Then, the imaginary part of the complex impedance is taken as the electrochemical impedance value of the cell. Of course, in other embodiments, the real and imaginary parts can be taken simultaneously for judgment, for example, the impedance magnitude or impedance phase angle can be calculated as a health status assessment index. The battery cluster management unit can also compare the test data of the cells under different temperatures and health status conditions to determine the health status of each string of cells in the system.

[0052] It should be noted that the battery cluster management unit calculates the electrochemical impedance value of each cell based on the current and voltage data obtained in each excitation cycle according to pre-set rules. For example, when the battery cluster management unit obtains the complex current vector and complex voltage vector corresponding to each excitation current cycle, it calculates the electrochemical impedance value under each excitation current cycle, and then uses the average value of the calculated electrochemical impedance values ​​under each excitation current cycle as the final electrochemical impedance value. Alternatively, the electrochemical impedance values ​​can be sorted by size, and the electrochemical impedance value in the middle position after sorting can be selected as the final electrochemical impedance value. It is understood that those skilled in the art can also use other statistically acceptable impedance value determination methods, as long as the final electrochemical impedance value can be calculated from the measurement data of multiple excitation cycles, which will not be elaborated in this embodiment.

[0053] In one embodiment, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0054] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0055] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A battery management unit, characterized in that, The system includes an energy exchange device (11), a microcontroller (12), an analog front-end (13), and a first sampling resistor (14). The energy exchange device (11) includes a capacitor (111), an inductor (112), a first MOSFET (113), a second MOSFET (114), and a driver chip (115). The analog front-end (13) includes at least a first analog input terminal (131) and a second analog input terminal (132). The first end of the capacitor (111) and the first end of the inductor (112) are both used to connect to the positive terminal of the battery module formed by connecting the multiple battery cells in series. The second end of the capacitor (111) is connected to the first end of the first MOS transistor (113). The second end of the inductor (112) and the first end of the second MOS transistor (114) are both connected to the second end of the first MOS transistor (113). The second end of the second MOS transistor (114) and the first analog input terminal (131) are both connected to the first end of the first sampling resistor (14). The second end of the first sampling resistor (14) is used to connect to the negative terminal of the battery module formed by connecting the multiple battery cells in series. The second end of the first sampling resistor (14) is also connected to the second analog input terminal (132). The driver chip (115) includes a first control signal output pin (1151) and a second control signal output pin (1152). The first pin is connected to the third terminal of the first MOS transistor (113), and the second pin is connected to the third terminal of the second MOS transistor (114). The microcontroller (12) is used to output control signals to the driver chip (115) to drive the first control signal output pin (1151) and the second control signal output pin (1152) of the driver chip (115) to output closed or open signals.

2. The battery management unit as described in claim 1, characterized in that, Also includes: The microcontroller (12) is communicatively connected to the analog front end (13), and the microcontroller (12) is also used to receive voltage data and current data sent by the analog front end (13).

3. An electrochemical impedance spectroscopy device for an energy storage system, characterized in that, It includes a power supply (100), a battery cluster management unit (200), a precharge circuit (300), a second sampling resistor (400), and at least one battery management unit (500) as described in claim 1, wherein, The first end of the power supply (100) and the first end of the precharge circuit (300) are used to connect to the positive terminal of the battery pack. The second end of the precharge circuit (300) is used to connect to the positive terminal of the load. The second end of the power supply (100) is connected to the battery cluster management unit (200). The battery cluster management unit (200) is communicatively connected to the battery management unit (500). The first end of the second sampling resistor (400) is used to connect to the positive terminal of the battery pack. The second end of the second sampling resistor (400) is used to connect to the negative terminal of the load. The power supply (100) is used to supply power to the battery cluster management unit (200); The battery pack management unit is used to send an electrochemical impedance detection signal to the battery management unit (500) and to obtain an electrochemical impedance value based on the current data and voltage data sent by the battery management unit (500).

4. The electrochemical impedance spectroscopy device for energy storage systems as described in claim 3, characterized in that, The precharge circuit (300) includes at least a discharge contactor (301), a charging contactor (302), a precharge contactor (303), a discharge diode (305), and a precharge resistor (304). The first end of the discharge contactor (301) and the first end of the precharge contactor (303) are used to connect to the positive terminal of the battery pack. The second end of the discharge contactor (301) is connected to the second end of the charging contactor (302). The second end of the charging contactor (302) is used to connect to the load. The second end of the precharge contactor (303) is connected to the first end of the precharge resistor (304), and the second end of the precharge resistor (304) is used to connect to the load.

5. The electrochemical impedance spectroscopy device for energy storage systems as described in claim 3, characterized in that, The precharge circuit (300) can also be replaced by a precharge control module, which includes an integrated circuit or component with precharge control function.

6. A method for detecting electrochemical impedance spectroscopy in an energy storage system, characterized in that, For implementation via the energy storage system electrochemical impedance spectroscopy device as described in any one of claims 3-5, comprising: The energy exchange device controls the alternating excitation of the battery module by alternately switching the conduction states of the first MOSFET and the second MOSFET during each excitation current cycle. During each excitation current cycle, current data flowing through the battery module and voltage data across each cell in the battery module are collected by an analog front end. For each battery cell, the multiple current and voltage data are converted in the frequency domain to obtain the complex current vector and complex voltage vector of each battery cell. The electrochemical impedance value of the battery cell is obtained based on the current complex vector and the voltage complex vector.

7. The method for detecting electrochemical impedance spectroscopy in an energy storage system as described in claim 6, characterized in that, The energy exchange control device performs alternating excitation on the battery module by alternately switching the conduction states of the first MOSFET and the second MOSFET during each excitation current cycle, including: During each excitation current cycle, the first MOSFET is turned off, and the second MOSFET is turned on for a first preset time before the first MOSFET is turned off again, and the second MOSFET is turned off, so that the inductor charges the capacitor. When the current flowing through the inductor is zero, the first MOSFET is controlled to close and the second MOSFET is controlled to open, so that the capacitor discharges into the inductor. When the current collected when the capacitor discharges to the inductor reaches a preset current threshold, the first MOSFET and the second MOSFET are both turned off, so that the inductor charges the battery module.

8. The method for detecting electrochemical impedance spectroscopy in an energy storage system as described in claim 7, characterized in that, After the inductor charges the battery module, the following is also included: Charging stops when the current from the inductor charging the battery module is 0.

9. The method for detecting electrochemical impedance spectroscopy in an energy storage system as described in claim 7, characterized in that, The step of obtaining the electrochemical impedance value of the battery cell based on the current complex vector and the voltage complex vector includes: Calculate the ratio of the current complex vector to the voltage complex vector to obtain the ratio result; The imaginary part of the ratio result is determined to be the electrochemical impedance value of the battery cell.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method as described in claims 6-9.

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