Electrochemical impedance spectroscopy system and method

Abstract

Electrochemical impedance spectroscopy systems and methods. An electrochemical impedance system includes a vehicle battery, a battery management system (BMS), an excitation power supply module, and a current sensor. The vehicle battery in turn includes one, two, or more battery modules. Each battery module includes a plurality of battery cells. The BMS is configured to control the excitation power supply module to excite at least the one, two or more battery modules. The current sensor is configured to sense current of at least the one, two or more battery modules. The BMS is further configured to sense, determine, or receive voltages of the plurality of battery cells of the one, two, or more battery modules, and also receive currents of the one, two, or more battery modules sensed by the current sensor. In this way, the system of the present disclosure can determine the electrochemical impedance of the vehicle battery. A corresponding method is also provided.

Description

Technical Field

[0001] This application relates to an electrochemical impedance spectroscopy (EIS) system. The EIS system is configured to determine the electrochemical impedance of a vehicle battery. For this purpose, the system is equipped with a battery management system that controls an excitation power module configured to excite the vehicle battery. The system can also be configured to generate a battery cell degradation output based at least on the determined impedance. A corresponding method is also provided. Background Technology

[0002] Electric vehicles (EVs) have at least an electric motor and a vehicle battery. In operation, the electric motor is adapted to provide propulsion to the vehicle, for example, by driving a drivetrain connected to the vehicle's wheels. EVs can be pure electric vehicles, electric-only vehicles, or fully electric vehicles. EVs can also include hybrid electric vehicles, which combine a conventional internal combustion engine system with an electric propulsion system.

[0003] Different types of batteries are used to power electric motors. Lithium-ion batteries are the most commonly used technology in electric vehicles. However, other types of vehicle batteries are known. In any case, operating the vehicle battery within predefined safety limits to ensure the safety of the user and the electric vehicle is crucial.

[0004] During use, vehicle batteries will experience aging, wear, or degradation. The purpose of monitoring and controlling the (high-voltage) vehicle batteries in electric vehicles throughout their lifecycle is to maximize efficiency while extending their remaining lifespan.

[0005] The State of Health (SOH) of a vehicle battery is a measure of its current condition or performance compared to its ideal or original condition when it was brand new. SOH is usually expressed as a percentage, with 100% indicating that the vehicle battery is in perfect condition, and lower percentages indicating aging, wear, or degradation. In fact, SOH helps assess the remaining lifespan of a vehicle battery and indicates when replacement or maintenance may be necessary.

[0006] Improving and optimizing energy management, as well as extending battery life, are key issues for the automotive industry. Recent innovations in computing and electronics have brought significant progress to the implementation of battery control. The use of novel artificial intelligence and other predictive models helps improve the accuracy of battery state-of-the-art (SOH) estimation. Battery remaining life is closely related to SOH.

[0007] Furthermore, battery degradation can lead to hazardous events, with thermal runaway being the most well-known. The State of Safety (SOS) of a vehicle battery refers to an assessment of its safety condition, ensuring that its operation does not pose a risk of fire, explosion, leakage, or other hazardous conditions. SOS assesses the vehicle battery's ability to operate safely under normal and stress conditions, including extreme temperatures, overcharging, physical damage, and other environmental factors. Therefore, monitoring SOS is also an important metric to consider in the field of electric vehicle technology.

[0008] State of Charge (SOC) can be defined as an indication of the current charge level of a vehicle's battery, typically expressed as a percentage, showing how much energy is available for use. Existing algorithms have achieved significant results in estimating SOC; however, SOH requires more complex algorithms, and SOS calculations for electric vehicle batteries remain challenging.

[0009] In known existing technologies, the algorithms used for State of Health (SOH) and State of Operation (SOS) in battery management systems rely on measurement signals from the vehicle battery. Specifically, known battery management systems utilize direct measurements such as voltage, current, and temperature to calculate these metrics. However, the accuracy of these calculations depends on the performance of the underlying algorithms.

[0010] Therefore, it is desirable to provide a system and method for determining the electrochemical impedance of a vehicle battery, in order to eliminate the aforementioned drawbacks and provide an advantageous solution to the shortcomings of the prior art. Summary of the Invention

[0011] One object of the present invention is to provide an electrochemical impedance spectroscopy system configured at least to determine the electrochemical impedance of a vehicle battery. For clarity and brevity, this electrochemical impedance spectroscopy system will be referred to as "the System" below.

[0012] The system includes a vehicle battery, a battery management system (BMS), or a battery management system (BMS). Multiple voltage sensors may also be provided, preferably as part of the battery management system. The system also includes an excitation power module and current sensors.

[0013] A vehicle battery is located within a motor vehicle (used to drive a configured electric motor) to move its wheels as needed. Vehicle batteries can be high-voltage batteries used in electric and hybrid vehicles. The operating voltage of a vehicle battery may be higher than 100 volts, for example, in the range of 200 to 1000 volts. The specific voltage depends on the vehicle type and the manufacturer's design. In essence, a vehicle battery is a rechargeable battery used to provide power to an electric vehicle, for example, to an electric operating system (further explained below). The primary function of a vehicle battery is to provide the necessary power to electric operating systems, such as traction systems. Additionally, vehicle batteries can also power low-voltage systems, which may include auxiliary electrical components such as lights, infotainment systems, and sensors.

[0014] A vehicle battery includes one, two, or more battery modules. Each battery module includes multiple battery cells. That is, a vehicle battery includes at least one battery module, namely a first battery module. The first battery module includes multiple battery cells arranged adjacent to each other. The vehicle battery may preferably include a second battery module, which may in turn include multiple battery cells arranged adjacent to each other. Of course, a third battery module and more battery modules may also be provided in the vehicle battery.

[0015] Each of the plurality of voltage sensors may be electrically connected to one, two, or more battery modules (i.e., at least to the first and / or second battery module). Each voltage sensor may be configured to sense the voltage of at least one or more battery cells (e.g., a group of battery cells). The battery management system may include a cell monitoring controller or CMC, which may include the plurality of voltage sensors.

[0016] The excitation power module (also referred to herein as an EIS excitation generator or excitation power converter) is electrically connected to the vehicle battery (e.g., connected to one, two, or more battery modules) and the battery management system. The excitation power module can be configured to excite at least one, two, or more battery modules. That is, the excitation power module can generate electricity with a non-constant current disturbance to be received by the battery cells. For this purpose, the battery management system is configured to control the excitation power module as needed.

[0017] A current sensor can be configured to sense the current of one, two, or more battery modules (i.e., at least the first and / or the second battery module). The current sensor can be connected to one, two, or more battery modules (i.e., at least the first and / or the second battery module).

[0018] As described above, the system is configured at least to determine the electrochemical impedance of a vehicle battery. The electrochemical impedance of a vehicle battery refers to the resistance exhibited by the battery's electrochemical structure to the flow of alternating current within a certain frequency range. It combines the resistive and reactive components of the vehicle battery's internal resistance and provides insight into the various processes occurring within the vehicle battery, such as charge transfer, diffusion, and double-layer capacitance. Specifically, the system is configured to perform electrochemical impedance spectroscopy to determine the internal impedance value of the system (in this particular application, the battery cell). The impedance of a battery cell has both resistive and reactive values; therefore, impedance is a complex value. To calculate it, the current and voltage through the battery cell are measured, and then Ohm's law is applied to calculate the magnitude of the impedance, and the phase is obtained from the phase change. The determination of electrochemical impedance can be performed using either potentiostatic or galvanostatic techniques.

[0019] A constant potential mode or technique involves applying a constant DC potential and superimposing a non-constant (or AC / sine wave) disturbance. The input or excitation signal is a potential (or voltage), and the resulting current response is measured, both using a sensor.

[0020] Constant current mode, or technique, involves applying a constant current and superimposing a small non-constant current perturbation. In this case, the excitation input signal is current, and the resulting voltage response is measured.

[0021] To determine the impedance, the system requires spectral analysis of the impedance to determine the reactance of the battery cell. Therefore, the system involves voltage and current signals ranging from low to high frequencies (e.g., 0.1 to 4000 Hz). It is desirable that the excitation input signal is non-constant, ideally a sine wave. However, if frequency analysis is performed on the measurement signal, other discontinuous signals, such as square waves, can be applied.

[0022] The excitation input signal (current or voltage) (constant current or constant potential mode) is controlled by the battery management system. A unique excitation input signal can be generated for one, two, or more battery modules. Voltage perturbation response can be measured at the multiple battery cell level, while current perturbation response can be measured at the two or more battery module level to successfully characterize the impedance of the multiple battery cells. The measured signal typically enters an analog-to-digital interface and is then processed to calculate the impedance. In any case, the excitation signal through the battery cell should be small enough not to alter the cell's conditions, such as its state of charge.

[0023] Battery cells are inherently nonlinear systems; however, impedance can only be defined or calculated for linear systems. If linear time-invariant conditions are assumed, the impedance of the cell can be approximated. Linearization of such a system requires the following conditions to be met: - Causality: The system's response to a disturbance must be generated solely by the applied disturbance or excitation signal; - Linear: The relationship between disturbance and response must follow the linear differential law; - Stability: The system should exhibit minimal variation relative to environmental conditions (especially the state of charge, temperature, and voltage levels of the battery cells); - Stability: The system must remain stable over time, which means that once the disturbance is removed, it should return to its initial state.

[0024] The Battery Management System (BMS) is electrically connected to the vehicle battery. In practice, the BMS is at least configured to control the vehicle battery. The BMS may be responsible for acquiring data and signals from the vehicle battery and performing basic controls, including at least directly operating the battery pack assemblies and communicating with other controllers. For example, the BMS is configured to receive multiple measurements from the vehicle battery, including at least one of the following: current, cell voltage, and one or more temperatures. Additionally, the BMS can receive measurements such as gases (e.g., H2, CO, CO2), pressure, insulation, and leakage. The BMS processes these values, which can be transmitted to an external controller, such as the vehicle controller, via a bus communication channel. Furthermore, the BMS can use these measurements (or instructions or commands) received via the bus communication channel to directly operate battery pack assemblies, such as junction box contactors / relays, operate the thermal management system, balance battery cells, or calculate estimated parameters of the battery state, such as state of charge (SOC) or state of health (SOH).

[0025] In use, the battery management system is configured to specifically sense or determine the voltage of the plurality of battery cells in the one, two, or more battery modules (i.e., at least the first and / or second battery modules). Furthermore, the battery management system is configured to receive the current of the one, two, or more battery modules (i.e., at least the first and / or second battery modules) sensed by a current sensor.

[0026] Thanks to this system, the impedance of the plurality of battery cells can be calculated, estimated, or determined, at least in part, based on current and voltage. There are two options for determining the impedance of the plurality of battery cells: First: The battery management system is configured to determine the impedance of the plurality of battery cells in the one, two or more battery modules based at least on current and voltage.

[0027] Second: The battery management system is configured to send current and voltage to an external controller, which is configured to determine the impedance of the plurality of battery cells of the one, two or more battery modules based at least on the current and voltage.

[0028] The system can be further configured to monitor the electrochemical degradation of battery cells by determining impedance changes compared to one or more previous measurements. In fact, one result of electrochemical impedance spectroscopy can be used to monitor battery cell degradation, and it can also be used to detect hazardous events, such as early warnings of thermal runaway.

[0029] In any case, a preliminary analysis or study of the battery cell impedance is required early in its lifespan. To achieve this analysis, a dataset obtained from previous aging tests can be used, in which impedance data has been determined at each stage. This approach allows for the calculation of the degradation state of the cells within a vehicle over its lifespan. The electrochemical impedance spectroscopy results can then be compared with one or more previous measurements, and the impedance changes can be used, for example, to determine more accurate real-time battery estimates.

[0030] Preliminary analysis or research on battery cell impedance can be performed early in the battery's lifespan. To achieve this analysis, a dataset obtained from previous aging tests can be used, in which impedance data was determined at each stage. This method allows for the calculation of the degradation state of battery cells within a vehicle throughout its lifespan.

[0031] The accuracy of impedance results depends on the voltage and current sensors. The measurement resolution and accuracy preferably meet the requirements of the Kramers-Kronig conditions to ensure linear cell response and stable conditions. Therefore, if a small-amplitude perturbation response is expected, the sensor resolution should be designed accordingly, as phase difference detection accuracy is crucial for impedance measurement.

[0032] Preferably, the current sensor is a single current sensor, i.e., a single-cell current sensor. This current sensor is configured to sense the current of at least two or more battery modules (at least the first and second battery modules). For this purpose, the current sensor can be connected (directly or indirectly) to two or more battery modules (at least to the first and second battery modules). The reason for using a single current sensor is that the vehicle battery configuration is known in advance. If all battery cells are connected in series, the current of each battery cell is the measured current. If a parallel group exists, the assumption of an equivalent load distribution can be applied. If an imbalance exists, the measured voltage may present a different voltage response for the entire parallel group. Using a single current sensor in electrochemical impedance spectroscopy helps reduce the cost of the solution and provides a simplified solution where the current measurement can be used (simultaneously) for impedance calculations in the power converter control loop and the BMS.

[0033] A current sensor can be electrically positioned between the excitation power module and the vehicle battery. The term "between" should be understood as meaning the current sensor can be included within either the excitation power module or the vehicle battery. Therefore, the current sensor may be (physically) positioned within the battery management system, a junction box (described below), or the power operating system. If the current sensor is positioned within a junction box, it can be part of the junction box circuitry that receives / supplyes high power (further explained below). Alternatively, if the current sensor is positioned within the power operating system or a junction box, it may not be part of the power operating system circuitry that receives / supplyes high power. Importantly, the current sensor is electrically connected to an electrical connection device suitable for connecting the excitation power module and the vehicle battery, regardless of its physical location.

[0034] Preferably, the excitation power module is a single excitation power module. In operation, the excitation power module is configured to excite at least two or more battery modules (first and / or second battery modules), such as all battery modules.

[0035] Preferably, the excitation power module is located outside the vehicle battery and battery management system. Alternatively, the excitation power module may be located in a junction box (in a circuit separate from the contactor) or in an on-board charger as a module independent of the powertrain (i.e., the traction system).

[0036] The excitation power module, vehicle battery, current sensor and battery management system form a circuit that can be electrically isolated from the power flowing through the junction box and / or the power operating system (at least received by the traction system).

[0037] The electric operating system can be at least one of the following: an air conditioning system, a low-voltage system, an on-board charger or OBC, and a traction system (i.e., a vehicle propulsion system). The traction system may include an electric powertrain, also known as an electric motor. Specifically, the electric operating system can be equipped with or connected to multiple devices. Furthermore, when a stop / stop mode is anticipated, the junction box contactor or relay may disconnect, allowing the vehicle battery to be isolated to perform electrochemical impedance spectroscopy, thereby ensuring stable conditions. If the driving mode is activated, the junction box contactor or relay may close, allowing at least the traction system to receive power from the vehicle battery.

[0038] The difference between this invention and most existing technologies lies in the fact that the execution of the current and voltage measurement process for impedance calculation and characterization is not defined at the vehicle level considering the various components within the vehicle that must participate to successfully complete the impedance measurement. Therefore, this invention requires control of the battery connection system, including junction box contactors, high-voltage bus measurements (including high-voltage and high-voltage current), synchronization of cell voltage and battery current, and the reception and subsequent data processing by the BMS and other ECUs.

[0039] Preferably, the battery management system is configured to receive vehicle input signals. The battery management system is also configured to determine a system trigger command based at least on the vehicle input signals. The vehicle input signals are related to at least the vehicle state and the vehicle battery state.

[0040] The vehicle status is at least one of the following: parked mode, ignition off, or vehicle not started. Additionally, the vehicle battery status includes whether the vehicle battery is receiving and / or supplying power. This ensures the stability and linearity of the vehicle battery.

[0041] Preferably, the battery management system is further configured to receive or generate a start command. Thus, the system's trigger command is based on this start command.

[0042] Conversely, the initiation command is based on at least one predefined event, such as a predefined time, a predefined distance, and instructions from the user or driver.

[0043] Preferably, the system's trigger command is also based on the vehicle battery temperature and / or a preset time. More preferably, the trigger command is delayed by a preset time or until the vehicle battery temperature is below a preset temperature.

[0044] Preferably, the vehicle input signal is received from an external controller. For example, the external controller may be located outside the system. Alternatively, the vehicle input signal is received (directly) via a vehicle communication channel (e.g., CAN-BUS communication).

[0045] Preferably, the battery management system or external controller is configured to receive changes in vehicle state (e.g., parking mode) or vehicle battery state (e.g., a change in the power supplied by the vehicle battery). In the event of a change in vehicle state and / or vehicle battery state, the battery management system or external controller can be configured to stop determining impedance.

[0046] The system's trigger command can also be based on cell balancing of the vehicle's battery to ensure stable conditions. Optionally, the trigger command is delayed until cell balancing is complete. This ensures that all battery cells are at the same voltage level and that impedance measurements will be uniform.

[0047] In use, this system or an external controller (with an embedded algorithm) is further configured to generate a battery cell degradation output based at least on the determined impedance. The (embedded) algorithm may include an artificial intelligence module, such as a trained machine learning module. Alternatively, it may be a data analysis or data association system. During its lifespan, the battery cell degrades, losing some electrochemical properties. Cell degradation affects the remaining lifespan of the battery and the vehicle. If this gradual degradation is detected, the vehicle's energy management can be adjusted towards optimized and more efficient energy use. Furthermore, electrochemical impedance spectroscopy results can be used for forensic analysis; to check battery status in the event of an accident; or for second-life use to determine battery status and consider more suitable applications.

[0048] Preferably, the excitation power module includes an energy storage device and an energy modulator. In use, the energy storage device can be configured to store electrical energy to supply the energy modulator. Conversely, the energy modulator can be configured to generate a (variable) excitation current signal to the vehicle battery. Therefore, the excitation current signal enables the excitation power module (e.g., the energy modulator) to excite at least one, two, or more battery modules, thereby allowing a (single) current sensor to sense the current of at least one, two, or more battery modules during excitation. The variable excitation current signal to the vehicle battery can be understood as a non-constant electrical signal that varies over time, and its nature can be periodic or aperiodic. Examples of such signals include, but are not limited to, sine waves, polytone signals, square waves, triangular waves, or binary pulse sequences. The signal is configured to be capable of frequency domain decomposition, i.e., it contains frequency components other than zero, allowing analysis of the battery impedance as a function of frequency.

[0049] The system may also include a first switching device connected to the vehicle battery. The first switching device can be configured to switch between an open position and a closed position. Furthermore, an energy modulator may be associated with the first switching device. During operation of the excitation power module, the first switching device is in the open position.

[0050] When the first switch is in the open position, the vehicle battery is electrically isolated, or the EIS system is operating. When the first switch is closed, the vehicle battery can supply power, for example, to the electric motor.

[0051] The system may also include a second switching device connected to the vehicle battery. The second switching device can be configured to switch between an open position and a closed position. Furthermore, an energy modulator may be associated with both the first and second switching devices. During operation of the excitation power module, the first switching device is in the open position, and the second switching device is in the closed position.

[0052] When both (the first and second switching devices) are open, the vehicle battery is electrically isolated. When both (the first and second switching devices) are closed, the vehicle battery can supply power, for example, to the electric motor. During operation of the excitation power module, the first switching device is in the open position and the second switching device is in the closed position.

[0053] Furthermore, in this disclosure, the first and / or second switching devices may be electronic devices such as transistors, or electromechanical devices such as contactors or relays.

[0054] The excitation power module and the vehicle battery are electrically connected to each other via at least a first conductor and a second conductor. The first and second conductors are connected to terminals of the vehicle battery. Preferably, a first switching device can be connected to the first conductor, and a second switching device can be connected to the second conductor. Specifically, the first and second conductors are configured to be connected to the positive and negative terminals of the vehicle battery, respectively. That is, the first conductor is a positive cable, wire, or busbar. Similarly, the second conductor is a negative or ground cable, wire, or busbar. In any case, when connected to the corresponding terminals of the vehicle battery, the potential of the second conductor may optionally be lower than the potential of the first conductor.

[0055] The system may also include a switch controller. The switch controller can be configured to control the open and closed positions of the first and second switch devices.

[0056] Preferably, the first switching device defines a first side and a second side. The first side is arranged between the energy storage device and the first switching device. Conversely, the second side is arranged between the first switching device and the vehicle battery.

[0057] The energy modulator may preferably include a first branch and a second branch, wherein the first branch is electrically connected to the second branch. The first branch is (directly) electrically connected to a first side of a first switching device, and the second branch is (directly) electrically connected to a second side of the first switching device.

[0058] Furthermore, the energy modulator may also include a third branch. When provided, the third branch is (directly) electrically connected to the first and second branches. In operation, the third branch is electrically connected to either side of the second switching device. In other words, the third branch can be (directly) electrically connected to either the first or second side of the second switching device. The first side of the second switching device is arranged between the energy storage device and the second switching device, while the second side of the second switching device is arranged between the second switching device and the vehicle battery.

[0059] A branch (i.e., the first, second, and third branches) refers to a path or line in a circuit (e.g., to the first and / or second conductors) that conducts current between two points. A branch may consist of a single electrical line or include two or more electrical lines. In either case, each line or path preferably includes one or more electrical components.

[0060] The energy modulator may include inductors, resistors, and / or capacitors. Inductors, resistors, and / or capacitors can form current and / or voltage filters. Inductors, resistors, and / or capacitors may be associated with a second branch. Preferably, the second branch includes inductors, resistors, and / or capacitors, for example, attached to a junction box. In any case, the inductor can be configured to store energy when current flows through it, for example, in a magnetic field. Therefore, the inductor can be configured to receive electrical energy from a power source outside the junction box, such as from a DC-link capacitor or DC-DC converter, and accumulate energy while reducing voltage ripple, thereby ensuring a smoother and more stable power supply to the vehicle battery, which is particularly beneficial for achieving accurate electrochemical impedance spectroscopy (EIS) measurements. In practice, less signal filtering is required, and the current control loop does not exhibit severe spikes that could render the system uncontrollable. It is entirely possible for the second branch to further include one or more electronic components, such as additional resistors, additional capacitors, and / or additional inductors. If the second branch includes one or more additional capacitors and / or one or more additional inductors, a filter can be formed to reduce voltage ripple, such as a resonant filter.

[0061] Preferably, the energy modulator includes a first semiconductor switch. More preferably, the first semiconductor switch is operatively associated with a first branch. More preferably, the first branch includes the first semiconductor switch. For example, the first semiconductor switch may be a controllable transistor, such as a MOSFET or an IGBT (insulated-gate bipolar transistor). Because the first semiconductor switch can be controlled to open and close, the energy modulator is able to generate a variable excitation signal, thereby enabling precise electrochemical impedance spectroscopy (EIS) measurements.

[0062] Preferably, the energy modulator may further include a first anti-series semiconductor switch. More preferably, the first anti-series semiconductor switch is (operably) associated with and connected in series with the first semiconductor switch. In use, the conductive path of the first anti-series semiconductor switch is arranged in the opposite direction to the conductive path of the first semiconductor switch. When the EIS system is not operating, the first anti-series semiconductor switch is in the open state, and when the EIS system is operating, it is in the closed state, thereby allowing current to flow. In this way, the first anti-series semiconductor switch ensures that reverse current is prevented when the EIS system is not operating. Therefore, when the EIS system is not operating, the first anti-series semiconductor switch remains open. When the EIS system is operating, the first anti-series semiconductor switch switches to the closed state (e.g., not operating in PWM (pulse width modulation) mode), allowing bidirectional current flow. Subsequently, the first semiconductor switch begins switching operation (i.e., switching between the open and closed positions).

[0063] By controlling the open and closed states of the first anti-series semiconductor switch, short circuits in the vehicle battery can be prevented. Specifically, when the first anti-series semiconductor switch is open, current is blocked due to the presence of the first anti-series and the reverse diode of the first semiconductor switch; these diodes work together to counteract and eliminate any potential current path. This arrangement also allows for the safe disconnection of the EIS system in overcurrent conditions, reducing the risk of damage to system components. For example, the first anti-series semiconductor switch can be a controllable transistor, such as a MOSFET.

[0064] Preferably, the energy modulator may include a second semiconductor switch. The second semiconductor switch may (operably) be associated with a third branch. More preferably, the third branch includes the second semiconductor switch. For example, the second semiconductor switch may be a controllable transistor, such as a MOSFET or an IGBT (Insulated Gate Bipolar Transistor). Providing a third branch with a second semiconductor switch improves the regulation of the excitation current signal delivered to the vehicle battery. In particular, since the third branch is associated with a second terminal of the vehicle battery, it allows the generation and processing of variable excitation signals, such as AC signals including positive and negative components; that is, it allows the system to generate bidirectional currents and / or signals (i.e., both positive and negative). Specifically, the second semiconductor switch is in the open position when the first semiconductor switch is in the closed position (at least at a given instant). Similarly, the second semiconductor switch is in the closed position when the first semiconductor switch is in the open position (at least at a given instant).

[0065] Preferably, the energy modulator may include a second anti-series semiconductor switch. The second anti-series semiconductor switch may (operably) be associated with and connected in series with the second semiconductor switch. In use, the conductive path of the second anti-series semiconductor switch is arranged in the opposite direction to the conductive path of the second semiconductor switch.

[0066] Preferably, the energy modulator may further include a second anti-series semiconductor switch. More preferably, the second anti-series semiconductor switch may (operably) be associated with and connected in series with the third branch. In use, the conductive path of the second anti-series semiconductor switch is arranged in the opposite direction to the conductive path of the second semiconductor switch. When the EIS system is not operating, the second anti-series semiconductor switch is in the open state, and when the EIS system is operating, it is in the closed state, thereby allowing current to flow. In this way, the second anti-series semiconductor switch ensures that reverse current is prevented when the EIS system is not operating. Therefore, when the EIS system is not operating, the second anti-series semiconductor switch remains open. When the EIS system is operating, the second anti-series semiconductor switch switches to the closed state (e.g., not operating in PWM mode), allowing bidirectional current flow. Subsequently, the first semiconductor switch begins switching operation (i.e., switching between the open and closed positions).

[0067] By controlling the open and closed states of the second anti-series semiconductor switch, short circuits in the vehicle battery can be prevented. Specifically, when the second anti-series semiconductor switch is open, current is blocked due to the presence of the second anti-series and the reverse diodes of the second semiconductor switch; these diodes work together to counteract and eliminate any potential current paths. This arrangement also allows for the safe disconnection of the EIS system in overcurrent conditions, reducing the risk of damage to system components. For example, the second anti-series semiconductor switch can be a controllable transistor, such as a MOSFET.

[0068] An energy modulator may include two or more semiconductor switches (i.e., the first and second semiconductor switches explained above) to form at least a two-quadrant topology (i.e., a half-bridge). In use, it enables at least bidirectional current flow to modulate the excitation current signal. Furthermore, the energy modulator may include at least two additional semiconductor switches (i.e., the third and fourth semiconductor switches) to form a four-quadrant topology (i.e., a full-bridge or H-bridge). That is, the energy modulator may include four or more semiconductor switches (i.e., the first, second, third, and fourth semiconductor switches) controlled in such a way that at least bidirectional current flow and bidirectional voltage are achieved to modulate the excitation current signal.

[0069] Preferably, one or more semiconductor switches (e.g., first, second, third, and / or fourth semiconductor switches) are controlled by PWM (pulse width modulation) switching signals. The semiconductor switches are preferably configured to operate at high switching speeds to generate the desired variable excitation current signal. The PWM switching signal enables precise and rapid switching to achieve this high-frequency modulation, thereby allowing efficient regulation of the voltage and / or current delivered for performing electrochemical impedance spectroscopy (EIS) system operation.

[0070] The electrochemical impedance spectroscopy system may also include a semiconductor switch controller. The semiconductor switch controller may be configured to control the open and closed positions of the one or more semiconductor switches (e.g., a first / second / third / fourth semiconductor switch).

[0071] A semiconductor switch controller can be operatively connected to the one or more semiconductor switches, for example, arranged in a half-bridge or full-bridge topology. Therefore, the semiconductor switch controller can be configured to generate and transmit control switching signals, such as pulse-width modulation (PWM) switching signals, to selectively open and close the semiconductor switches.

[0072] In a half-bridge configuration, a semiconductor switch controller alternately drives two semiconductor switches (e.g., first and second semiconductor switches), one of which (e.g., the first semiconductor switch) is connected to the aforementioned first conductor (e.g., a positive voltage supply), and the other is connected to the second conductor (e.g., ground or negative). By modulating the duty cycle of the PWM signal applied to each semiconductor switch, the semiconductor switch controller can generate a variable voltage at the output node, preferably between 0 V and a reference voltage. This allows the excitation current signal to be delivered to the vehicle battery in a controlled manner, thereby facilitating improved EIS measurements.

[0073] In a full-bridge configuration, a semiconductor switch controller drives four semiconductor switches arranged in two complementary pairs. By selectively activating the diagonal pairs of switches in an alternating pattern and adjusting at least the duty cycle of the switch signals, the semiconductor switch controller can generate bidirectional variable electrical signals across the vehicle battery. This configuration enables the generation of AC signals (e.g., bipolar PWM waveforms) that can vary in amplitude, polarity, and frequency according to application requirements.

[0074] Through this controlled switching process, the semiconductor switch controller can precisely adjust the energy flow and waveform characteristics (i.e., the excitation current signal), which can be used as an injected diagnostic signal to operate the electrochemical impedance spectroscopy (EIS) system, thereby enabling accurate EIS measurements.

[0075] For operation of the EIS system, a switching device controller can instruct the (e.g., second) switching device located opposite the inductor to be in the closed position, while the (e.g., first) switching device associated with the inductor is in the open position. Furthermore, a semiconductor switching controller can instruct the (e.g., first) semiconductor switch associated with the inductor to be closed. In this way, energy from the energy storage device passes through the inductor and is received by the vehicle battery, returning to the energy storage device, for example, through the (e.g., second) switching device located opposite the inductor. Subsequently, the semiconductor switching controller can instruct the (e.g., first) semiconductor switch associated with the inductor to be closed. In this way, energy from the energy storage device does not pass through; instead, energy is supplied to the vehicle battery from the inductor, which was charged according to the previous stage (where the (e.g., first) switching device associated with the inductor is in the open position), and this energy may return to the inductor. Again, when the motor or any other load powered by the vehicle battery needs to be powered by the vehicle battery, the switching device controller prioritizes this operation over the EIS measurement and then instructs both (i.e., the first and second) switching devices to be in the closed position. When neither the vehicle battery is required to power the electric motor nor is an EIS measurement being performed, the switching device controller instructs both (i.e., the first and second) switching devices to be in the off position.

[0076] The semiconductor switch controller can be housed in a junction box. Alternatively or additionally, the semiconductor switch controller and switching device controller can be integrated into the electronic control unit, preferably housed in a junction box. It is still possible that the semiconductor switch controller and / or switching device controller are components of the battery management system or BMS.

[0077] The energy modulator can preferably be housed within the junction box. Conversely, it is advantageous to place the energy storage unit outside the junction box. Furthermore, as previously mentioned, the primary function of the junction box is to protect the integrity of the vehicle battery and other powertrain components, and to enable the safe connection and disconnection of the vehicle battery. Positioning the energy modulator within the junction box is advantageous because it ensures the accuracy of the output current measurement (at least when generating the excitation current signal). This configuration helps avoid or reduce the problem of a portion of the excitation current signal being absorbed by system components such as inverter filters or DC links. By integrating the energy modulator inside the junction box, the generated excitation current signal is less susceptible to interference from, for example, inverter filters or capacitive elements. As a result, the integrity and accuracy of the excitation current signal are better maintained, leading to more reliable EIS measurements and battery characterization.

[0078] The aforementioned current sensor can be attached to or form part of a high-voltage circuit, for example, in a junction box. As mentioned above, the current sensor can be a single current sensor used to sense the current of two or more modules of the vehicle battery.

[0079] Preferably, the energy storage device is or at least includes one of the following: a DC-link capacitor, an on-board charger system or OBC, a low-voltage converter, and a DC / DC converter. In other words, a DC-link capacitor, an on-board charger or OBC, a low-voltage converter, and / or a DC / DC converter can also act as an energy storage device. For example, the term "energy storage device" can refer to any component or system configured to store electrical energy (temporarily or for a longer period) to provide power to an energy modulator. When implemented, the energy storage device may include or be embodied in one or more DC-link capacitors, on-board chargers (OBCs), low-voltage converters, or DC / DC converters. While some of these components are not typically referred to as energy storage devices, they may include or be associated with energy storage elements (e.g., capacitors or intermediate storage stages) that perform energy storage functions in the context of implementing an excitation current signal.

[0080] A DC-link capacitor can be configured at least to filter the DC output of the motor inverter. For this purpose, the DC-link capacitor can be positioned between the DC / DC converter and the motor inverter. A low-voltage converter can be configured to convert high-voltage DC from the vehicle battery to low-voltage DC for use in low-voltage systems. A DC / DC converter is an electronic device that converts DC power from a first voltage level to a second, different voltage level. A DC / DC converter, or buck converter, can be configured to reduce the high voltage (e.g., above 400 V) from the vehicle battery to charge low-voltage systems (e.g., lights, infotainment systems, power steering, electronic control units, and sensors) at 12 V.

[0081] This system offers several technical advantages. In particular: - It requires fewer additional components because the same battery current sensor can be used for standard battery current monitoring and EIS (current) measurement; - The (battery) junction box can be placed close to the vehicle battery and battery management system (BMS), thereby reducing the required wiring length and associated energy loss; - The integration of the system within the (battery) junction box can be configured to exhibit minimal heat loss, as it can be thermally coupled to the battery contact plate or the battery cooling system. - The system is designed for easy maintenance, where replacement can be performed by simply replacing the (battery) junction box; - The energy storage is located within the vehicle powertrain system architecture, thus avoiding the need for external components or additional housings outside the vehicle structure.

[0082] According to one aspect of the present invention, a method for operating an electrochemical impedance spectroscopy system is provided. This method can be used to determine the electrochemical impedance of a vehicle battery. The method includes: - Provide a vehicle battery including a first battery module including a plurality of battery cells, and optionally, provide a second battery module including a plurality of battery cells; - Connect the battery management system electrically to the vehicle battery; - A circuit is formed by electrically connecting the first module and the excitation power supply module; - Connect the second module electrically to the circuit; - The current in the circuit is sensed by a current sensor; - Connect the excitation power module electrically to the battery management system; - Powers the excitation power supply module, which is configured as the excitation circuit; - The battery management system receives the current from the circuit sensed by the current sensor; - The voltage of multiple battery cells in the first battery module is sensed or determined by the battery management system; - Optionally, the voltage of multiple battery cells in the second battery module can be sensed or determined by the battery management system; - The impedance of multiple battery cells in the first battery module (and optionally the second battery module) is determined by the battery management system based at least on current and voltage, or The battery management system sends current and voltage to an external controller, which is configured to determine the impedance of multiple battery cells in the first battery module (and optionally the second battery module) based at least on the current and voltage.

[0083] The method may also include: - Receive vehicle input signals, wherein the vehicle input signals are at least related to the vehicle status and the vehicle battery status; - The system's trigger command is determined based at least on vehicle input signals; - Preferably, a startup command is received or generated, wherein the system's trigger command is also based on the startup command. Optionally, the startup command is based at least on a predefined event, for example, on one of the following: - Predefined time, - Predefined distance, and - Instructions from the user or driver.

[0084] The method may also include: - Disconnect the first switching device. If a second switching device is also provided, it is preferable to close the second switching device. Optionally, the first switching device is disconnected at least at the instant the second switching device is closed; - In the first stage, the first semiconductor switch is closed, wherein energy from the energy storage of the power module is received by the vehicle battery through an inductor. This energy can be returned to the energy storage, preferably through a second switching device; and In the second stage, the first semiconductor switch is disconnected, where energy from the energy storage device does not pass through the first semiconductor switch, and the inductor supplies energy to the vehicle battery. This energy can then be returned to the inductor, for example, through a second semiconductor switch or a diode. Attached Figure Description

[0085] Non-limiting examples of this disclosure will be described below with reference to the accompanying drawings.

[0086] In the attached diagram: Figure 1 This is a schematic diagram of an electrochemical impedance spectroscopy system, which is connected to an external controller and a junction box, which is also connected to a power operating system. Figure 2 Is with Figure 1 A similar schematic diagram shows the excitation input signal generated by the excitation power supply module and the current measured by the unit current sensor; Figure 3 This is a schematic diagram showing an electrochemical impedance spectroscopy system without a vehicle battery; Figure 4 This is an overview diagram showing the electrochemical impedance spectroscopy system implemented in a vehicle scenario; Figure 5 This is a schematic diagram showing that the battery management system, cell current sensor, and excitation power module form a circuit that is electrically isolated from the high power flowing through the junction box and / or power operating system. Figure 5 A possible vehicle implementation is further illustrated, in which an external controller is connected to the circuit, which is connected to the vehicle battery, the vehicle battery is connected to a junction box, and the junction box is connected to the power operating system. Figure 6 This is a schematic diagram of an excitation power supply module, which includes an energy storage device arranged outside the junction box and an energy modulator arranged inside the junction box. The energy modulator includes a first branch and a second branch. Figure 7 Is with Figure 6 A similar schematic diagram further illustrates that the energy modulator includes a first semiconductor switch associated with the first branch and an inductor associated with the second branch; Figure 8 Is with Figure 7 A similar schematic diagram further illustrates a first anti-series semiconductor switch connected in series with the first semiconductor switch; Figure 9 Is with Figure 7A similar schematic diagram further illustrates that the energy modulator includes a diode associated with the third branch; Figure 10 Is with Figure 9 A similar diagram, in which Figure 10 Specifically shown is the second semiconductor switch (in place of the diode) associated with the third branch; Figure 11 Is with Figure 10 A similar schematic diagram further illustrates a second anti-series semiconductor switch connected in series with the second semiconductor switch; and Figure 12 This is a schematic diagram illustrating an energy modulator comprising a semiconductor switch with at least a four-quadrant topology, such as a full-bridge configuration of a MOSFET. Detailed Implementation

[0087] Figure 1 The diagram illustrates an electrochemical impedance spectroscopy system connected to an external controller 200 and a junction box 300. The junction box 300 is in turn connected to a power operating system 400. For clarity and simplicity, this electrochemical impedance spectroscopy system will be referred to as "this system" below.

[0088] exist Figure 1 In a non-limiting example, the power operating system 400 includes different subsystems, such as a traction system 410, an air conditioning system 420, a low-voltage system 430, and an on-board charger system 440 or OBC.

[0089] Junction box 300 is a vehicle junction box. Junction box 300 includes contactors 301, 302 and / or relays for connecting vehicle battery 10 to power operating system 400. When contactors 301, 302 are open, vehicle battery 10 and power operating system 400 are in an electrically isolated state. When contactors 301, 302 are closed, vehicle battery 10 and power operating system 400 are in an electrically connected state.

[0090] The external controller 200 is, in particular, a vehicle controller (VCU), such as a vehicle control unit. It is connected to a vehicle bus communication channel, such as a CAN bus. The external controller 200 can obtain signals from the vehicle bus communication channel (e.g., the CAN bus). These signals may include at least data related to the parking mode (or other vehicle modes, such as driving mode). If the parking mode is selected, the contactor or relay in the junction box is open. If the driving mode is selected, the contactor or relay in the junction box is closed.

[0091] As shown in the figure, the electrochemical impedance spectroscopy system includes an EIS excitation power supply module 30, a vehicle battery 10, a battery management system 20 or BMS, and a current sensor 40.

[0092] Figure 1The vehicle battery 10 shown includes two or more battery modules M1, M2. Each battery module M1, M2 includes multiple battery cells C1, C2, C3 (in the example shown, C1, C2, C3 refers to a group of battery cells).

[0093] The battery management system (BMS) 20 is configured to control the vehicle battery 10, for example, two or more battery modules M1, M2. In particular, the battery management system (BMS) 20 is configured to perform cell balancing of the vehicle battery 10, for example, two or more battery modules M1, M2, which is at least partially derived from voltage measurements from voltage sensors (described below).

[0094] More specifically, the Battery Management System (BMS) 20 includes a Cell Monitoring Controller (CMC) 21 and a Battery Monitoring Controller (BMC) 22. The Cell Monitoring Controller (CMC) 21 includes voltage sensors configured to sense or determine the voltages of two or more battery modules M1, M2. Specifically, the voltage sensors include multiple voltage sensing devices VS1, VS2, each configured to sense or determine the voltages V1, V2, V3 of multiple battery cells C1, C2, C3 within the two or more battery modules M1, M2. Furthermore, the Cell Monitoring Controller (CMC) 21 is also configured to perform cell equalization. Additionally, the Battery Monitoring Controller (BMC) 22 includes a main (micro) controller that runs algorithms and performs calculations (e.g., electrochemical impedance spectroscopy).

[0095] In this example, the excitation power module 30 is a single excitation power module. The excitation power module 30 is electrically connected to the vehicle battery 10 and the battery management system (BMS) 20. Furthermore, the excitation power module 30 is configured to excite at least two or more battery modules M1, M2. The battery management system (BMS) 20 is specifically configured to instruct or control the excitation power module 30 to generate an excitation input signal. In particular, Figure 1 The illustration shows that the excitation power module 30 is arranged outside of circuits involving high power, such as the circuits of the vehicle battery 10, junction box 300, and traction system 410.

[0096] like Figure 2As shown, current sensor 40 is electrically connected to two or more battery modules M1, M2. For example, it can be directly connected (e.g., via a shunt resistor) or indirectly connected (e.g., via a Hall sensor). Thus, current sensor 40 is configured to sense the current (I) of at least two or more battery modules M1, M2, particularly the current of all battery modules in vehicle battery 10. Furthermore, current sensor 40 is electrically connected to battery management system (BMS) 20. Therefore, battery management system (BMS) 20 is configured to receive the current (I) of two or more battery modules M1, M2 sensed by current sensor 40.

[0097] In this example, current sensor 40 is a unit current sensor. Specifically, current sensor 40 is electrically connected between EIS excitation power module 30 and vehicle battery 10. Current sensor 40 can be located in excitation power module 30, vehicle battery 10, or junction box 300. As shown, an electrical connection device electrically connects EIS excitation power module 30 and vehicle battery 10 to each other. This electrical connection device includes two cables or wires, for example, a positive and a negative terminal. Current sensor 40 is (directly) connected to the electrical connection device or conductor.

[0098] The battery management system (BMS) 20 is configured to determine the impedances Z1, Z2, Z3, Z1', Z2', Z3' of multiple battery cells C1, C2, C3, C1', C2', C3' of two or more battery modules M1, M2 based at least on current I and voltage V1, V2, V3, V1', V2', V3'. Alternatively, the battery management system (BMS) 20 is configured to send current I and voltage V1, V2, V3, V1', V2', V3' to an external controller 200, which is configured to determine the impedances Z1, Z2, Z3, Z1', Z2', Z3' of multiple battery cells C1, C2, C3, C1', C2', C3' of two or more battery modules M1, M2 based at least on current I and voltage V1, V2, V3, V1', V2', V3'.

[0099] The battery management system (BMS) 20 or external controller 200 is configured to determine the electrochemical impedance Z of the vehicle battery 10 (e.g., Z1, Z2, Z3 of battery cells C1, C2, C3). Specifically, the amplitude and phase of the electrochemical impedance are determined by applying Ohm's law to the current I and voltage V1, V2, V3 input to the vehicle battery cells C1, C2, C3. The determination of the electrochemical impedance Z is performed in either a constant potential mode (i.e., applying a constant DC potential and superimposing an AC / sine wave perturbation) or a constant current mode (i.e., applying a constant current and superimposing a small non-constant current perturbation).

[0100] The Battery Management System (BMS) 20 or external controller 200 is further configured to monitor the electrochemical degradation of battery cells C1, C2, and C3 by determining the impedance change compared to one or more previous measurements of battery cells C1, C2, and C3 (which may include measurements performed at the factory or measurements based on previous aging tests). To determine the impedance Z, the BMS 20 or external controller 200 needs to perform a spectral analysis of the impedance Z to determine the resistance / reactance values ​​of battery cells C1, C2, and C3. In the example, the EIS excitation power module 30 generates voltage and current signals to the vehicle battery 10 in a frequency range of 0.1 to 4000 Hz. These voltage and current signals are part of an excitation input signal i(f), which in this example comprises a sine wave or a square wave. Other types of waveforms can, of course, be used as long as the excitation input signal i(f) contains disturbances. Then, based on the impedance Z measurement, the impedance curve is obtained, which allows the derivation of the equivalent circuit model (ECM) of the vehicle battery 10 (e.g., multiple battery cells C1, C2, C3). This enables an understanding of how it changes or degrades.

[0101] The excitation input signal i(f) is generated at the cell level, with one excitation signal for each cell C1, C2, C3, or a single excitation input signal i(f) for multiple cells C1, C2, C3 connected in parallel and / or series. The perturbation response (voltage or current) is measured at the cell level C1, C2, C3 to successfully characterize the battery cell impedance Z. Alternatively, the perturbation of multiple cells C1, C2, C3 can be obtained through a single measurement, but the accuracy of the results will be reduced. In a non-limiting example, the measured signal enters an analog-to-digital interface and is then processed to calculate the impedance Z. In any case, the excitation input signal i(f) through the battery cells C1, C2, C3 is small enough not to alter the conditions of the battery cells, such as their state of charge.

[0102] Therefore, the battery management system (BMS) 20 is configured to receive or determine voltage and current measurements from multiple voltage sensors VS1, VS2 and current sensors 40, respectively. The battery management system (BMS) 20 or the external controller 200 can then process these measurements to determine the state of the vehicle battery 10. The battery management system (BMS) 20 or the external controller 200 is also configured to control contactors 301, 302 of the junction box 300.

[0103] In a non-limiting example, the battery management system (BMS) 20 is configured to receive additional measurements from the vehicle battery 10, such as temperature, gases (e.g., H2, CO, CO2), pressure, insulation, and leakage. The battery management system (BMS) 20 processes these values, which can be transmitted to an external controller 200 via the vehicle bus communication channel, or can be used internally.

[0104] In the example, tracking impedance states can be used to enhance SoH and SoS.

[0105] EIS performs frequency analysis using voltage and current measurements based on Ohm's law. If voltage excitation input signals are generated at the battery cell level (C1, C2, C3) and the current response is measured at the battery module level (M1, M2), EIS can be performed in constant-potential mode. Alternatively, constant-current mode uses a current excitation input signal, with the disturbance being the voltage drop across cells C1, C2, C3. EIS analysis requires stable conditions for the vehicle battery 10; therefore, the preferred mode is constant-current mode, as it does not affect the system-on-chip (SoC) or temperature of battery cells C1, C2, C3. EIS should report the impedance curves of battery cells C1, C2, C3 as a function of frequency. The frequency range to be analyzed is between 0.1 Hz and 1 kHz. However, for practical applications, a small number of frequencies (5 to 10) are sufficient to study the evolution of impedance Z over the entire vehicle battery lifespan.

[0106] To perform constant current EIS, a controlled power supply module acts as a current source and is directly connected to the vehicle battery 10. As shown, this system is a circuit independent of the power operating system 400. Therefore, the operation of the EIS excitation power supply module 30 can only occur when the power operating system 400 is disconnected from the vehicle battery 10.

[0107] like Figure 2 As shown, the excitation input (EIS current) signal i(f) to the vehicle battery 10 is sensed by a current sensor 40, which reports signal I to the BMS controller. The battery 10 consists of different modules M1, M2, where the independent voltage measurements of each cell C1, C2, C3 report voltage responses V1, V2, V3 to the BMS controller. The voltage values ​​V1, V2, V3 and the current I are then used to calculate the cell-level impedances Z1, Z2, Z3. These impedance results are subsequently used in algorithms within the BMS or other controllers to determine the SoX value and enhance vehicle operation.

[0108] EIS is (in essence) not a recurring analysis because battery degradation is not sudden. Testing can be performed periodically, at the request of the user or driver, or due to an event. Therefore, the vehicle controller (BMS) 200 (or BMC 22) automatically creates a trigger command after a predefined distance, predefined time, or upon driver instruction. This command is transmitted to the battery management system (BMS) 20 via the vehicle bus communication channel. The BMS 20 records the request and checks the vehicle status. As previously mentioned, EIS must be performed under stable conditions. Therefore, the vehicle must be stopped, in parking mode, and there must be no connection between the vehicle battery 10 and the motor drive or charging bus. If the vehicle battery 10 is isolated from the power operating system 400 (e.g., powertrain 410), the BMS 20 sends a wake-up command to the EIS converter controller. The EIS excitation power module 30 is configured with internally predefined parameters, or commanded by the BMS 20. EIS is then performed, and the excitation input current i(f) is reported to the BMS 20 (see...). Figure 2 Voltage disturbances are sensed by CMC 21. After EIS is completed, BMS 20 sends another command to EIS excitation power module 30 to stop it and put it back into sleep mode. Finally, once impedance data processing is complete, the predefined distance or timer counter in external controller 200 (or BMC 22) will be reset.

[0109] According to the Kramers-Kroning conditions, the system can be ensured to be causal and physically consistent. For EIS, the main conditions are causality, linearity, and stability. The stability and linearity of battery cells C1, C2, and C3 can be better ensured under constant current analysis because small potential perturbations through battery cells C1, C2, and C3 can lead to significant current perturbation responses, which may affect battery cell conditions, such as changes in state of charge, resulting in an unstable and nonlinear response.

[0110] In the example, the battery management system (BMS) 20 is further configured to receive or generate a start command. This start command is based at least on one of a predefined time, a predefined distance, and a command from the user or driver. For example, the predefined time could be one year, and the predefined distance could be 100,000 kilometers. Of course, other times and distances are also possible.

[0111] The trigger command of the aforementioned system is also based on this start command. The Battery Management System (BMS) 20 is configured to receive a Vehicle Input Signal (VIS). Specifically, the Battery Management System (BMS) 20 is configured to determine the trigger command based at least on the Vehicle Input Signal (VIS). The Vehicle Input Signal (VIS) is related to at least the vehicle state and the vehicle battery state. The vehicle state is at least one of the following: parking mode, ignition off, vehicle not started. The vehicle state is used to determine whether the vehicle battery is receiving and / or supplying power.

[0112] In a non-limiting example, the trigger command is further delayed by a preset time or until the temperature of the vehicle battery 10 is below a preset temperature. More specifically, the trigger command is delayed until cell equalization is complete.

[0113] In all cases, the vehicle input signal VIS is received from the external controller 200 or via the vehicle bus communication channel. In this example, the external controller 200 is positioned outside the electrochemical impedance spectroscopy system. Specifically, the battery management system (BMS) 20 or the external controller 200 is configured to receive changes in the vehicle battery state of interest (SOX) or the vehicle state. In use, the battery management system (BMS) 20 and the external controller 200 are configured to stop determining impedances Z1, Z2, and Z3 based on changes in the vehicle battery state or the vehicle state.

[0114] Figures 6 to 12 A vehicle battery system is shown, which includes the electrochemical impedance spectroscopy system described herein. The vehicle battery system may also include a junction box 300, and / or a DC link 311, and / or an OBC 440 (see [link to OBC]). Figure 1 ), and / or low-voltage converter 312 (see Figures 9 to 12 The vehicle battery system can supply power to an electric motor inverter (not shown). The electric motor inverter operably converts the DC power supplied by the battery system into AC power to drive the electric motor. The electric motor then provides the mechanical torque required to drive the wheels of an electric or hybrid vehicle, such as a passenger car.

[0115] A DC link capacitor 311 is configured to at least filter the DC output of the motor inverter. For this purpose, the DC link capacitor 311 is arranged between the DC / DC converter and the motor inverter. A low-voltage converter 312 is configured to convert high-voltage DC from the vehicle battery 10 into low-voltage DC for the low-voltage system 430. A DC / DC converter is an electronic device that converts direct current (DC) power from a first voltage level to a second different voltage level. The DC / DC converter is configured to reduce the high voltage from the vehicle battery 10, for example, above 400V, to charge the low-voltage system 430 (e.g., lights, infotainment system, power steering, electronic control unit, and sensors). The low-voltage system 430 operates at a voltage between 5 and 25V.

[0116] Figures 6 to 12 The excitation power supply module is shown to include an energy storage unit 31 and an energy modulator 32. The energy modulator 32 is disposed within a junction box 300, while the energy storage unit 31 is disposed outside the junction box 300. Positioning the energy modulator 32 within the junction box 300 is advantageous because it improves the current measurement accuracy of the current sensor 40 when operating the EIS system (i.e., when an excitation current signal is generated). It reduces the problem of a portion of the excitation current signal being absorbed by filters (e.g., inverter filters). This reduces the likelihood that a portion of the excitation current signal will be absorbed by filters (e.g., inverter filters). By integrating the energy modulator 32 inside the junction box 300, the generated excitation current signal is less affected by the capacitive elements of the inverter (i.e., interference associated with the DC link capacitor 311). As a result, a more reliable EIS system is achieved.

[0117] The energy storage device 31 is configured to store electrical energy to supply the energy modulator 32. In use, the energy modulator 32 is configured to generate a variable excitation current signal to the vehicle battery 10.

[0118] like Figures 6 to 12 As shown, the excitation power module is electrically connected to the vehicle battery 10 via a first conductor 11 and a second conductor 12. The first and second conductors 11 and 12 are connected to the terminals of the vehicle battery 10. The first conductor 11 is a bus connected to the positive terminal of the vehicle battery 10, and the second conductor 12 is a bus connected to the negative terminal of the vehicle battery 10.

[0119] Figures 6 to 12 A first switching device 51 associated with the first conductor 11 is shown, for example, connected to the positive terminal of the vehicle battery 10. Furthermore, a second switching device 52 is associated with the second conductor 12, for example, connected to the negative terminal of the vehicle battery 10. The second switching device 52 is optional and not required. If provided, it can improve the electrical isolation of the vehicle battery 10, for example, when both the first and second switching devices 51 and 52 are in the off position.

[0120] The first and second switching devices 51 and 52 are configured to switch from an open position to a closed position and vice versa. The first and second switching devices 51 and 52 are controlled by a switching device controller (not shown) for switching purposes. Specifically, the switching device controller is located within the junction box 300. For example, the first and second switching devices 51 and 52 are electromechanical devices, such as contactors or relays, but other types of switching devices, such as electronic devices, can certainly be used.

[0121] Figure 6 The diagram also illustrates the energy modulator 32, which includes a first branch 321, a second branch 322, and an optional third branch 323. Figure 6 (Not shown in the image). For example... Figures 6 to 8 As shown, the third branch 323 is not provided, but... Figures 9 to 12 The branch road is provided in the text.

[0122] As shown in the figure, the first branch 321 is electrically connected to the second branch 322. When provided, the third branch 323 is electrically connected to the first and second branches 321 and 322.

[0123] like Figures 6 to 12 As shown, the first switching device 51 defines a first side 511 and a second side 512. The first side 511 is arranged between the energy storage device 31 and the first switching device 51, while the second side 512 is arranged between the first switching device 51 and the vehicle battery 10. Similarly, the second switching device 52 defines a first side 521 and a second side 522 (see...). Figure 9 and Figure 10 (Referring to the reference numerals in the accompanying drawings). The first side 521 of the second switching device 52 is arranged between the energy storage device 31 and the second switching device 52, while the second side 522 is arranged between the second switching device 52 and the vehicle battery 10.

[0124] In the example, the first branch 321 is directly electrically connected to the first side 511 of the first switching device 51, while the second branch 322 is directly electrically connected to the second side 512 of the first switching device 51. In the example, the third branch 323 is directly electrically connected to the first side 521 of the second switching device 52. However, the third branch 323 may also be directly connected to the second side 522 (not shown).

[0125] Figure 7The diagram illustrates a first branch 321 including a first semiconductor switch 325. For example, the first semiconductor switch 325 is a controllable transistor, such as a MOSFET. The first semiconductor switch 325 is controlled by a PWM switching signal. The system also includes a semiconductor switch controller (not shown) configured to control the open and closed positions of the first semiconductor switch 325 via the PWM switching signal. Specifically, the semiconductor switch controller is disposed within a junction box 300. Because the first semiconductor switch 325 can be controlled to open and close, the energy modulator 32 is able to generate a variable excitation signal, thereby enabling accurate EIS measurements.

[0126] Furthermore, the second branch 322 includes an inductor 329. In use, the inductor 329 is configured to store energy in a magnetic field when current flows through it, while reducing voltage ripple, thereby ensuring a smoother and more stable power supply to the vehicle battery 10, which is particularly beneficial for achieving accurate EIS measurements. Therefore, the inductor 329 is configured to receive electrical energy from a power source external to the junction box 300. In this example, the power source external to the junction box 300 is a DC-link capacitor 311, but it could also be from an OBC 440, a low-voltage converter 312, or a DC / DC converter. It is entirely possible for the second branch to further include one or more capacitors and / or one or more additional inductors for this purpose. Thus, the one or more capacitors and / or the one or more additional inductors can be connected in association with the inductor 329 to form a filter, such as a resonant filter. Specifically, the inductor 329 is part of or attached to the junction box 300.

[0127] When the switching device controller instructs the first and second switches 51 and 52 to be in the open position, the vehicle battery 10 does not supply power. Conversely, when the switching device controller instructs both the first and second switches 51 and 52 to be in the closed position, the vehicle battery 10 supplies power. When the switching device controller instructs the first switch 51 to be in the open position and the second switch 52 to be in the closed position, the EIS system generates an excitation current signal to determine the impedances Z1 and Z2 of the battery modules M1 and M2. Specifically, according to the first stage, the semiconductor switching controller instructs the first semiconductor switch 325 to close. In this way, energy from the energy storage 31 passes through the inductor 329 and is received by the vehicle battery 10, returning to the energy storage 31, for example, through the second switch 52. Subsequently, according to the second stage, the semiconductor switching controller instructs the first semiconductor switch 325 to open. In this way, energy from the energy storage 31 does not pass through; instead, the inductor 329, which was charged in the first stage, provides energy to the vehicle battery 10.

[0128] In this example, a current sensor 40 is disposed within a junction box 300 for sensing current during an excitation current signal. Specifically, the current sensor 40 is disposed in either the first conductor 11 or the second conductor 12. More specifically, the current sensor 40 is disposed on the second side 512 of the first switching device 51 or the second side 522 of the second switching device 52.

[0129] Figure 8 A first anti-series semiconductor switch 325' connected in series with the first semiconductor switch 325 is further shown. Therefore, the first branch 321 also includes the first anti-series semiconductor switch 325'. As shown, the conductive path of the first anti-series semiconductor switch 325' is arranged in the opposite direction to the conductive path of the first semiconductor switch 325.

[0130] By controlling the open and closed states of the first anti-series semiconductor switch 325', short circuits in the vehicle battery 10 can be prevented. Furthermore, current flows in only one direction.

[0131] When the EIS system is not operating, the first anti-series semiconductor switch 325' is in the open state, thereby preventing reverse current flow. Conversely, when the EIS system is operating, the first anti-series semiconductor switch 325' is in the closed state, thereby allowing bidirectional current flow. In this way, the first anti-series semiconductor switch 325' is used to prevent short circuits in the vehicle battery and allows the EIS system to be safely disconnected in the event of overcurrent, thereby reducing the risk of damage to system components.

[0132] Figure 9 The third branch 323 is illustrated. The third branch 323 includes a first terminal and a second terminal. The first terminal is connected between the energy storage device 31 and the first semiconductor switch 325. For example, when an anti-series semiconductor switch 325' is provided, the first terminal is directly connected between the anti-series semiconductor switch 325' and the first semiconductor switch 325 (not shown). The second terminal is connected to the second conductor 12. A diode is provided in the third branch 323 as a protection component and is configured to prevent current spikes.

[0133] Figure 10The third branch 323 further includes a second semiconductor switch 326. For example, the second semiconductor switch 326 is a controllable transistor, such as a MOSFET. The second semiconductor switch 326 is controlled by a PWM switching signal. The semiconductor switch controller is further configured to control the open and closed positions of the second semiconductor switch 326 via the PWM switching signal. Because the second semiconductor switch 326 can be controlled to open and close, the energy modulator 32 is able to generate a variable excitation current signal, thereby improving the accuracy of the EIS measurement. Specifically, when the first semiconductor switch 325 is in the open position, the second semiconductor switch 326 is in the closed position, and vice versa.

[0134] Figure 11 The first branch 321 is depicted as including a first semiconductor switch 325 and a first anti-series semiconductor switch 325' (as previously described). Figure 8 The third branch 323 further includes a second semiconductor switch 326 and a second anti-series semiconductor switch 326'. As shown, the conductive path of the second anti-series semiconductor switch 326' is arranged opposite to the conductive path of the second semiconductor switch 326. By controlling the open and closed states of the second anti-series semiconductor switch 326', short circuits of the vehicle battery 10 can be prevented. Furthermore, current flows in only one direction in the third branch 323. Specifically, when the EIS system is not operating, the second anti-series semiconductor switch 326' is in the open state, thereby preventing reverse current flow. Conversely, when the EIS system is operating, the second anti-series semiconductor switch 326' is in the closed state, thereby allowing bidirectional current flow. Thus, the first anti-series semiconductor switch 325' is used to prevent short circuits of the vehicle battery and allows safe disconnection of the EIS system in the event of overcurrent, thereby reducing the risk of damage to system components.

[0135] Figure 12 The diagram illustrates an energy modulator 32 comprising at least four semiconductor switches 325, 326, 327, and 328 arranged in two complementary pairs, e.g., a full-bridge configuration of MOSFETs. In operation, a semiconductor switch controller is configured to select / activate the diagonal pairs of semiconductor switches 325, 326, 327, and 328 in an alternating mode and adjust at least the duty cycle of the switching signals. This configuration enables the generation of AC signals, e.g., bipolar PWM waveforms, which can vary in amplitude, polarity, and frequency according to application requirements.

[0136] In both two-quadrant topologies (e.g., half-bridge) and four-quadrant topologies (e.g., full-bridge), bidirectional current flow is at least achieved to modulate the excitation current signal for exciting (one) two or more battery modules M1, M2. If a four-quadrant topology (e.g., full-bridge) is implemented, bidirectional voltage is further achieved.

[0137] The method for operating an electrochemical impedance spectroscopy system includes the following steps: A vehicle battery 10 is provided, including a first battery module M1 and a second battery module M2. The first battery module M1 includes multiple battery cells C1, C2, and C3. The second battery module M2 also includes multiple battery cells C1', C2', and C3'.

[0138] The battery management system (BMS) 20 is electrically connected to the vehicle battery 10. The battery management system (BMS) 20 includes a cell monitoring controller (CMC) 21 and a battery monitoring controller (BMC) 22.

[0139] A circuit is formed by electrically connecting at least a first module M1 and an excitation power supply module 30. This circuit may not be a high-voltage circuit. Furthermore, the method includes electrically connecting a second module M2 to the circuit (i.e., the excitation power supply module 30 and the first and second modules M1 and M2 form the circuit).

[0140] Connect the excitation power module 30 electrically to the battery management system (BMS) 20.

[0141] Connect the current sensor 40 electrically to the circuit.

[0142] Power is supplied to the excitation power module 30, which is configured to excite the circuit.

[0143] When the circuit is energized, the current I of the circuit is sensed by the current sensor 40.

[0144] The battery management system (BMS) 20 receives the current I of the circuit sensed by the current sensor 40.

[0145] The battery management system (BMS) 20 senses, determines, or receives the voltages V1, V2, and V3 of multiple battery cells C1, C2, and C3 of the first battery module M1.

[0146] The battery management system (BMS) 20 senses, determines, or receives the voltages V1', V2', and V3' of multiple battery cells C1', C2', and C3' in the second battery module M2.

[0147] The battery management system (BMS) 20 determines the impedances Z1, Z2, Z3, Z1', Z2', Z3' of multiple battery cells C1, C2, C3, C1', C2', C3' in the first battery module M1 and the second battery module M2 based at least on the current I and voltages V1, V2, V3, V1', V2', V3'. Alternatively, the method may include sending the current I and voltages V1, V2, V3, V1', V2', V3' to an external controller 200, which is configured to determine the impedances Z1, Z2, Z3, Z1', Z2', Z3' of multiple battery cells C1, C2, C3, C1', C2', C3' in the first battery module M1 and the second battery module M2 based at least on the current I and voltages V1, V2, V3, V1', V2', V3'.

[0148] The method also includes: Receive vehicle input signal (VIS). This vehicle input signal (VIS) is related to at least the vehicle status and the battery pack status.

[0149] The trigger command for the electrochemical impedance spectroscopy system is determined based at least on the vehicle input signal (VIS).

[0150] Receive or generate a start command. The triggering command of the electrochemical impedance spectroscopy system is also based on this start command. This start command is based at least on one of the following: a predefined time, a predefined distance, and a command from the user or driver.

[0151] The vehicle battery 10, junction box 300, and power operating system 400 are connected to each other to form a high-voltage circuit, which differs from the circuit described above. Furthermore, when the contactors 301, 302, and / or relays of the junction box 10 are in the open position, impedances Z1, Z2, Z3, Z1', Z2', and Z3' are determined.

[0152] The method also includes: The first switching device 51 is disconnected, and the second switching device 52 is closed when the second switching device 52 is provided. When the second switching device 52 is provided, the first switching device 51 is disconnected at least at the instant the second switching device 52 is closed.

[0153] In the first stage, the first semiconductor switch 325 is closed. For example, the first semiconductor switch 325 is closed at least at the instant the second semiconductor switch 326 is opened. In this way, energy from the energy storage 31 passes through the first semiconductor switch 325 and the inductor 329 and is received by the vehicle battery 10, returning to the energy storage 31, for example, through the second switching device 52. During this first stage, the inductor 329 is being charged.

[0154] In the second stage, the first semiconductor switch 325 is disconnected. For example, the first semiconductor switch 325 is disconnected at least at the instant the second semiconductor switch 326 is closed. Thus, energy from the energy storage device 31 does not pass through the first semiconductor switch 325. Instead, the inductor 329, which is charging in the first stage, provides energy to the vehicle battery 10, and this energy may return to the inductor 329, for example, through the second semiconductor switch 326 or... Figure 9 The diode described in the text.

[0155] Preferably, the opening and closing of the first semiconductor switch 325 and the second semiconductor switch 326 described above are repeated, i.e., the first and second stages. This operation is performed at a high switching speed to generate the required variable excitation current signal. The PWM switching signal enables precise and fast switching, which is necessary to achieve this high-frequency modulation.

[0156] Preferably, when the first anti-series semiconductor switch 325' is provided, the first anti-series semiconductor switch 325' is closed during EIS system operation, thereby allowing (bidirectional) current (flow) to reach the first semiconductor switch 325. When the second anti-series semiconductor switch 326' is provided, the second anti-series semiconductor switch 326' is closed during EIS system operation.

[0157] All possible combinations of the examples described herein are therefore covered. The scope of this disclosure should not be limited to any particular example, but should only be determined through a fair interpretation of the appended claims. If reference numerals are placed in the claims in connection with the drawings, they are only intended to increase the comprehensibility of the claims and should not be construed as limiting the scope of the claims.

Claims

1. An electrochemical impedance spectroscopy system, the electrochemical impedance spectroscopy system comprising: - Vehicle battery (10), the vehicle battery comprising one, two or more battery modules (M1, M2), wherein each battery module (M1, M2) comprises multiple battery cells (C1, C2, C3). - A battery management system (20) electrically connected to the vehicle battery (10), wherein the battery management system (20) is configured to sense, determine or receive the voltages (V1, V2, V3) of the plurality of battery cells (C1, C2, C3) of the one, two or more battery modules (M1, M2), wherein the battery management system (20) is configured to control the vehicle battery (10). - An excitation power module (30) electrically connected to the vehicle battery (10) and the battery management system (20), wherein the excitation power module (30) is configured to excite at least one, two, or more battery modules (M1, M2); and - A current sensor (40) configured to sense the current (I) of at least one, two or more battery modules (M1, M2) when they are energized. The battery management system (20) is configured to receive the current (I) from the one, two, or more battery modules (M1, M2) sensed by the current sensor (40), and The battery management system (20) is configured to determine the impedance (Z1, Z2, Z3) of the plurality of battery cells (C1, C2, C3) of the one, two, or more battery modules (M1, M2) based at least on the current (I) and the voltage (V1, V2, V3), or The battery management system (20) is configured to send the current (I) and the voltage (V1, V2, V3) to an external controller (200), which is configured to determine the impedance (Z1, Z2, Z3) of the plurality of battery cells (C1, C2, C3) of the one, two, or more battery modules (M1, M2) based at least on the current (I) and the voltage (V1, V2, V3).

2. The system according to claim 1, wherein, The current sensor (40) is a single current sensor electrically connected to two or more battery modules (M1, M2), wherein the current sensor (40) is configured to sense the current of at least the two or more battery modules (M1, M2).

3. The system according to claims 1 to 2, wherein, The excitation power module (30) is a single excitation power module, wherein the excitation power module (30) is configured to excite at least two or more battery modules (M1, M2).

4. The system according to claims 1 to 3, wherein, The excitation power module (30) is located outside the vehicle battery (10) and the battery management system (20).

5. The system according to claims 1 to 4, wherein, The current sensor (40) is electrically arranged between the excitation power module (30) and the vehicle battery (10), including being electrically arranged in the excitation power module (30), electrically arranged in the vehicle battery (10), or electrically arranged in the junction box (300).

6. The system according to claims 1 to 5, wherein the battery management system (20) is configured to receive a vehicle input signal (VIS), wherein, The vehicle input signal (VIS) is related to at least the vehicle state and the vehicle battery state, and the battery management system (20) is configured to determine the system's trigger command based at least on the vehicle input signal (VIS).

7. The system according to claim 6, wherein, The vehicle state is at least one of the following: parking mode, ignition off, vehicle not started, and wherein the vehicle battery state includes whether the vehicle battery is receiving and / or supplying power.

8. The system according to claims 6 to 7, wherein, The battery management system (20) is further configured to receive or generate a startup command, wherein the system's trigger command is also based on the startup command, preferably, the startup command is based on at least one of the following: - Predefined time, - Predefined distance, and - Instructions from the user or driver.

9. The system according to claims 6 to 8, wherein, The trigger command of the system is also based on the temperature of the vehicle battery (10) and / or a preset time. Preferably, the trigger command is delayed by the preset time or until the temperature of the vehicle battery (10) is lower than the preset temperature.

10. The system according to claims 6 to 9, wherein, The vehicle input signal (VIS) is received from the vehicle control unit (VCU) or via a vehicle bus communication channel, wherein the vehicle control unit (VCU) is located outside the system.

11. The system according to claims 6 to 10, wherein, The battery management system (20) or the external controller is configured to receive a change in the vehicle battery state or the vehicle state, and wherein the battery management system (20) or the external controller is configured to stop determining the impedance (Z1, Z2, Z3) based on the change in the vehicle battery state or the vehicle state.

12. The system according to claims 6 to 11, wherein, The system's trigger command is also based on the cell balancing of the vehicle battery (10). Preferably, the trigger command is delayed until the cell balancing is completed.

13. A method for operating an electrochemical impedance spectroscopy system, the method comprising: - Provide a vehicle battery (10), the vehicle battery including a first battery module (M1), the first battery module including a plurality of battery cells (C1, C2, C3); - Connect the battery management system (20) to the vehicle battery (10). - A circuit is formed by electrically connecting at least the first module (M1) and the excitation power supply module (30); - Connect the excitation power module (30) to the battery management system (20). - Connect the current sensor (40) electrically to the circuit; - Power the excitation power supply module (30), which is configured to excite the circuit; - At least when the circuit is energized, the current (I) of the circuit is sensed by the current sensor (40). - The current (I) of the circuit sensed by the current sensor (40) is received by the battery management system (20). - The battery management system (20) senses, determines or receives the voltages (V1, V2, V3) of the plurality of battery cells (C1, C2, C3) of the first battery module (M1). as well as - The battery management system (20) determines the impedances (Z1, Z2, Z3) of the plurality of battery cells (C1, C2, C3) of the first battery module (M1) based at least on the current (I) and the voltage (V1, V2, V3), or The current (I) and the voltage (V1, V2, V3) are sent to an external controller, which is configured to determine the impedance (Z1, Z2, Z3) of the plurality of battery cells (C1, C2, C3) of the one, two, or more battery modules (M1, M2) based at least on the current (I) and the voltage (V1, V2, V3).

14. The method according to claim 13, wherein, The method further includes: - Provide a second battery module (M2) to the vehicle battery (10), the second battery module (M2) including a plurality of battery cells (C1', C2', C3'); - Connect the second module (M2) electrically to the circuit; - The battery management system (20) senses or determines the voltages (V1, V2, V3, V1', V2', V3') of the plurality of battery cells (C1, C2, C3, C1', C2', C3') of the first battery module (M1) and the second battery module (M2); and - The battery management system (20) determines the impedance (Z1, Z2, Z3, Z1', Z2', Z3') of the plurality of battery cells (C1, C2, C3, C1', C2', C3') of the first battery module (M1) and the second battery module (M2) based at least on the current (I) and the voltage (V1, V2, V3, V1', V2', V3').

15. The method according to claims 13 to 14, wherein, The method further includes: - Receive vehicle input signal (VIS), wherein the vehicle input signal (VIS) is related to at least the vehicle state and the battery pack state; - The trigger command of the system is determined at least based on the vehicle input signal (VIS); and - Preferably, a startup instruction is received or generated, wherein the system's trigger command is further based on the startup instruction, and optionally, the startup instruction is based on at least one of the following: - Predefined time, - Predefined distance, and - Instructions from the user or driver.

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