Patent Application
20250004061
The present invention relates to the field of batteries, and more particularly to a control method and device for impedance spectrum measurement of a battery, a vehicle electronic control unit, a computer-readable storage medium, a computer program product, a system for impedance spectrum measurement of a battery, and a vehicle.
In electrochemical impedance spectrum measurement, variation characteristics of an impedance (parameters such as an amplitude value of the impedance or a phase angle of the impedance) of an electrochemical system as a function of frequency are calculated by applying an alternating current disturbance or an alternating voltage disturbance to the electrochemical system and measuring a ratio of an alternating voltage signal to an alternating current signal.
With continuous development of fuel cells, more and more attention has been paid to electrochemical impedance spectrum measurement of the fuel cells. By measuring the electrochemical impedance spectrum of the fuel cells, many details about working states of the fuel cells can be reflected.
Currently, impedance spectrum characteristics of fuel cells can be measured in the laboratory, but such a measurement method in the laboratory requires the preparation of particular measurement devices and the construction of a particular test platform, which is costly and cannot reflect on-line impedance characteristics of the fuel cells.
Additionally, impedance spectrum measurement of a battery can be implemented by controlling a power electronic device at an output end of the battery to inject disturbances into the battery. However, the highest frequency at which measurement can be performed in this solution is very limited. Moreover, when a system current is small (that is, in a low-current condition), a disturbance current may enable a current output by the battery to the power electronic device to be negative, that is, a current reversal phenomenon occurs, which is often unbearable by the battery.
According to an aspect of the present invention, a control method for impedance spectrum measurement of a battery is provided. The battery outputs a power via a DC-DC converter. The control method includes: sending a first signal, where the first signal indicates a conduction mode of the DC-DC converter to be set, and the conduction mode includes a discontinuous conduction mode or a critical conduction mode; receiving a current measurement value and a voltage measurement value at an output end of the battery; and calculating an impedance spectrum of the battery based on the received current measurement value and the received voltage measurement value.
As an alternative or addition to the above solution, in the control method according to an embodiment of the present invention, the conduction mode further includes a continuous conduction mode. If at least one of the battery, the DC-DC converter, and a load of the battery meets a predetermined criterion, the first signal indicates the DC-DC converter to be set to the discontinuous conduction mode or the critical conduction mode, otherwise, the first signal indicates the DC-DC converter to be set to the continuous conduction mode.
As an alternative or addition to the above solution, the control method according to an embodiment of the present invention further includes: fusing the impedance spectra calculated in different conduction modes.
As an alternative or addition to the above solution, in the control method according to an embodiment of the present invention, the predetermined criterion includes: a current of the load of the battery being less than a predetermined threshold; and/or the battery being in a purge phase.
As an alternative or addition to the above solution, in the control method according to an embodiment of the present invention, when the DC-DC converter is set to the critical conduction mode, the control method further includes: sending a second signal, where the second signal indicates the load of the battery to be changed, so that a switching frequency of the DC-DC converter changes; receiving the current measurement values and the voltage measurement values at the output end of the battery at different switching frequencies; and calculating the impedance spectra of the battery at the different switching frequencies based on the received current measurement values and the received voltage measurement values at the different switching frequencies.
As an alternative or addition to the above solution, the control method according to an embodiment of the present invention further includes: fusing the calculated impedance spectra at the different switching frequencies.
According to another aspect of the present invention, a control device for impedance spectrum measurement of a battery is provided. The control device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. The computer program, when executed by the processor, implements the steps in the above control method for impedance spectrum measurement of a battery.
According to another aspect of the present invention, a vehicle electronic control unit is provided. The vehicle electronic control unit includes the above control device for impedance spectrum measurement of a battery.
According to another aspect of the present invention, a computer-readable storage medium is provided. The computer-readable storage medium has a computer program stored thereon. The computer program, when executed by a processor, implements the steps in the above control method for impedance spectrum measurement of a battery.
According to another aspect of the present invention, a computer program product including a computer program is provided. The computer program, when executed by a processor, implements the steps in the above control method for impedance spectrum measurement of a battery.
According to another aspect of the present invention, a system for impedance spectrum measurement of a battery is provided. The system for impedance spectrum measurement includes: a DC-DC conversion device configured to convert an output power of the battery, and transmit the converted power to a load, where a conduction mode of the DC-DC conversion device includes a discontinuous conduction mode or a critical conduction mode; a measurement device configured to measure an output current value and an output voltage value of the battery; and a calculation device for calculating an impedance spectrum of the battery based on the measured output current value and the measured output voltage value.
As an alternative or addition to the above solution, in the system according to an embodiment of the present invention, the conduction mode of the DC-DC conversion device further includes a continuous conduction mode. The system for impedance spectrum measurement further includes a switching device configured to: if at least one of the battery, the DC-DC conversion device, and the load meets a predetermined criterion, switch the DC-DC conversion device to the discontinuous conduction mode or the critical conduction mode, otherwise, switch the DC-DC conversion device to the continuous conduction mode.
As an alternative or addition to the above solution, in the system according to an embodiment of the present invention, the calculation device is further configured to fuse the impedance spectra calculated in different conduction modes.
As an alternative or addition to the above solution, in the system for impedance spectrum measurement according to an embodiment of the present invention, the predetermined criterion includes: a current of the load being less than a predetermined threshold; and/or the battery being in a purge phase.
As an alternative or addition to the above solution, the system according to an embodiment of the present invention further includes a sending device. The sending device is configured to send a second signal when the DC-DC conversion device is set to the critical conduction mode, where the second signal indicates the load to be changed, so that a switching frequency of the DC-DC conversion device changes. The measurement device is further configured to measure the output current values and the output voltage values of the battery at different switching frequencies. The calculation device is further configured to calculate the impedance spectra of the battery at the different switching frequencies based on the measured output current values and the measured output voltage values.
As an alternative or addition to the above solution, in the system according to an embodiment of the present invention, the calculation device is further configured to fuse the calculated impedance spectra at the different switching frequencies.
As an alternative or addition to the above solution, the system according to an embodiment of the present invention further includes the battery and/or the load.
According to a further aspect of the present invention, a vehicle is provided. The vehicle is equipped with the above system for impedance spectrum measurement of a battery.
In the control solution for impedance spectrum measurement of a battery according to the embodiments of the present invention, it is possible to use an inherent ripple of the DC-DC converter to measure the impedance spectrum of the battery in a low-current condition by setting the conduction mode of the DC-DC converter, thereby avoiding a problem of current reversal from the DC-DC converter to the battery in a measurement process. The control solution neither needs to add an additional harmonic power source to the battery or the DC-DC converter, nor needs to additionally control the DC-DC converter to generate harmonic disturbances. The control solution is simple to operate and easy to implement, and electrochemical impedance values of the battery at high frequencies can be measured.
Further, in the control solution for impedance spectrum measurement of a battery according to the embodiments of the present invention, the conduction mode of the DC-DC converter can be flexibly switched based on actual working conditions of the battery, the DC-DC converter, and the load, to reduce disturbances caused by the measurement to the system as much as possible on the premise of avoiding current reversal. Still further, in the control solution for impedance spectrum measurement of a battery according to the embodiments of the present invention, a range of measurement frequencies can be changed by changing the load in the critical conduction mode, to obtain electrochemical impedance information of the battery in more frequency ranges.
The above and other objects and advantages of the present invention will be more complete and clearer from the following detailed description in conjunction with the accompanying drawings, where the same or similar elements are denoted by the same reference numerals.
To make the objects, technical solutions, and advantages of the present invention clearer, the technical solutions for forming motor windings according to various exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It may be understood that the specific embodiments described herein are merely used to explain the present invention, but not to limit the present invention.
It should be noted that, in the context of the present invention, the terms such as “first” and “second” are used to distinguish similar objects, and are not intended to describe the order in terms of time, space, size, etc. Furthermore, the terms “including/comprising”, “having”, and similar expressions are intended to mean a non-exclusive inclusion, unless otherwise specifically stated.
In the context of the present invention, the term “vehicle” or other similar terms include general motor vehicles, such as passenger vehicles (including sport utility vehicles, buses, trucks, etc.), various commercial vehicles, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, etc. A hybrid vehicle is a vehicle with two or more power sources, such as a vehicle powered by a gasoline engine and an electric motor.
There is a measurement method for measuring an impedance spectrum of a battery by using an inherent ripple of a DC-DC converter at an output end of the battery as a disturbance current. In such a measurement method, the DC-DC converter is usually set to a continuous conduction mode. This is because the DC-DC converter has a smaller harmonic content and a lower harmonic amplitude value in the continuous conduction mode.
However, it has found that there are some drawbacks in such a measurement method. For example, when the system is in a low-current condition, it is difficult to implement the above measurement method. This is because, when a direct current of the system is small, an alternating disturbance caused by the inherent ripple of the DC-DC converter working in the continuous conduction mode may enable a total system current to be negative, that is, the current will reversely flow from the DC-DC converter into the fuel cell. This is often unbearable by the fuel cell. For this reason, the present invention proposes an improved solution for impedance spectrum measurement of a battery.
In step S510, a first signal is sent. The first signal indicates a conduction mode of the DC-DC converter 420 to be set. The conduction mode may be a discontinuous conduction mode or a critical conduction mode.
In step S520, a voltage measurement value VFC and a current measurement value iFC at an output end of the battery 410 set to the discontinuous conduction mode or the critical conduction mode in step S510 are received. The voltage measurement value VFC and the current measurement value iFC are obtained, for example, by a measurement apparatus such as a current transformer or a voltage transformer provided at the output end of the battery 410.
In step S530, an impedance spectrum of the battery is calculated based on the current measurement value iFC and the voltage measurement value VFC received in step S520. Specifically, measured current and voltage values in a time domain may be converted into current and voltage values in a frequency domain by means of a time-frequency transform (such as a Fourier transform (FT), a fast Fourier transform (FFT), or a Z-transform), and impedance values of the battery at different frequencies are then calculated respectively to form an electrochemical impedance spectrum (EIS) measurement result of the battery.
Therefore, the control method 5000 for impedance spectrum measurement of a battery implements impedance spectrum measurement of the battery by using an inherent ripple of the DC-DC converter in a low-current condition, without being limited by current reversal. This is because the current value output by the battery to the DC-DC converter in the discontinuous conduction mode and the critical conduction mode is always greater than zero. Therefore, using the inherent ripple of the DC-DC converter working in the two conduction modes as a disturbance current to the impedance spectrum measurement of the battery does not cause a problem of current reversal from the DC-DC converter to the battery.
The control method 5000 for impedance spectrum measurement of a battery can be flexibly applied to various scenarios, especially on-line measurement scenarios, without adding any additional measurement device or controlling the DC-DC converter to generate any additional voltage and current. This makes the control method simple to operate, easy to implement, and low in investment costs. Compared with the solution of additionally controlling the DC-DC converter to generate an additional disturbance current to measure an impedance of the battery, the control method 5000 can measure an impedance value at a higher frequency.
Optionally, the conduction mode indicated by the first signal in step S510 further includes a continuous conduction mode. If at least one of the battery 410, the DC-DC converter 420, and the load 430 meets a predetermined criterion, the first signal indicates the DC-DC converter 420 to be set to the discontinuous conduction mode or the critical conduction mode. If none of the battery 410, the DC-DC converter 420, and the load 430 meets the predetermined criterion, the first signal indicates the DC-DC converter 420 to be set to the continuous conduction mode.
As an example, the predetermined criterion may be the load 430 being in a low-current condition, for example, a current of the load 430 being less than a predetermined current threshold. In this case, an example of a waveform of the current measurement value iFC at the output end of the battery 410 is as shown in
It can be seen from
Herein, the current threshold may be 0.2 A, 0.5 A, 1 A, or any other current values that can indicate that the system is in a low-current condition.
As another example, the predetermined criterion may be alternatively the entire system being in any other suitable condition, for example, the battery 410 being in a purge phase.
Optionally, the impedance spectra of the battery 410 calculated in different conduction modes are fused. For example, when the impedance spectra of the battery calculated in the different conduction modes do not overlap in terms of frequency, these impedance spectra are directly combined into one impedance spectrum. When the impedance spectra of the battery calculated in the different conduction modes overlap in terms of frequency, screening, a weighted recombination, and other operations can be performed on impedances at an overlapping frequency. Therefore, a higher-precision impedance spectrum measurement result of the battery can be obtained by fusing a plurality of impedance spectra.
Therefore, in the control method 5000 for impedance spectrum measurement of a battery, the conduction mode of the DC-DC converter can be flexibly switched according to actual working conditions of the system, to select an appropriate conduction mode to implement impedance spectrum measurement of the battery. For example, as shown in
As an example, when the first signal in step S510 indicates the conduction mode of the DC-DC converter 420 to be set to the critical conduction mode, the control method 5000 for impedance spectrum measurement of a battery may further include the following steps.
In step S540 (not shown in the figure), a second signal is sent. The second signal indicates the load 430 to be changed, so that a switching frequency of the DC-DC converter 420 changes.
In the context of the present invention, “changing the load” is intended to mean changing various parameters of the load 430, for example, a power, a voltage, a current, and any other parameters that can change the switching frequency of the DC-DC converter 420. In the critical conduction mode, since the switching frequency of the DC-DC converter 420 may vary with the load 430, an inherent ripple frequency of the DC-DC converter 420 may also vary accordingly, that is, measurement frequency of the battery 410 may vary accordingly.
In step S550 (not shown in the figure), the voltage measurement values VFC and the current measurement values iFC at the output end of the battery at different switching frequencies are received. In addition, in step S560 (not shown in the figure), the impedance spectra of the battery 410 at the different switching frequencies are respectively calculated based on the received voltage measurement values VFC and the received current measurement values iFC at the different switching frequencies. Similar to the above, the impedance spectra of the battery at the different switching frequencies may be fused.
Therefore, when the DC-DC converter is in the critical conduction mode, the switching frequency of the DC-DC converter may be changed by changing the load, thereby changing the measurement frequency of the battery, so that more abundant and accurate impedance spectrum information can be obtained by the control method 5000 for impedance spectrum measurement of a battery.
The memory 710 may be a random access memory (RAM), a read-only memory (ROM), an electrically programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM) or an optical disk storage device, a magnetic disk storage device, or any other media capable of carrying or storing desired program code in the form of machine-executable instructions or data structures and capable of being accessed by the processor 720. The processor 720 may be any suitable dedicated or general-purpose processor such as a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or a digital signal processor (DSP).
Those skilled in the art can readily understand that the above control device 7000 for impedance spectrum measurement of a battery can be incorporated into a vehicle. For example, the battery under test may be a vehicle-mounted battery, and the DC-DC converter is a DC-DC converter that converts a high-voltage direct-current power of the vehicle-mounted battery into a low-voltage direct-current power required by a vehicle load. The control device 7000 may be an independent control device used for impedance spectrum measurement of a battery, or may be integrated into another control device such as an electronic control unit (ECU) or a domain control unit (DCU).
Additionally, those skilled in the art readily understand that the control method for impedance spectrum measurement of a battery provided in one or more of the embodiments of the present invention may be implemented by a computer program. For example, when a computer storage medium (such as a USB flash drive) storing the computer program is connected to a computer, the control method in one or more embodiments of the present invention can be performed by executing the computer program.
The DC-DC conversion device 820 is configured to convert an output power of the battery 810, and transmit the converted power to the load 830. A conduction mode of the DC-DC conversion device 820 includes a discontinuous conduction mode, a critical conduction mode, etc. The measurement device 840 is configured to measure an output current value iFC and an output voltage value VFC of the battery 810, and send the measured current value iFC and the measured voltage value VFC to the calculation device 850. The measurement device 840 includes any measurement apparatus capable of measuring a current value and a voltage value at an output port of the battery 810, such as a voltage transformer or a current transformer. The calculation device 850 is configured to calculate an impedance spectrum of the battery 810 based on the measured output current value iFC and the measured voltage value VFC. For example, measured output current and voltage values in a time domain may be converted into current and voltage values in a frequency domain by means of a time-frequency transform (such as a Fourier transform (FT), a fast Fourier transform (FFT), or a Z-transform), and impedance values of the battery at different frequencies are then calculated respectively to form an electrochemical impedance spectrum measurement result of the battery 810.
When the DC-DC conversion device 820 in the system 8000 is set to the discontinuous conduction mode or the critical conduction mode, a current of the DC-DC conversion device 820 is always positive. Therefore, a current output by the battery to the DC-DC conversion device 820 does not become negative even in a low-current condition. In this way, the system 8000 for impedance spectrum measurement of a battery can implement impedance spectrum measurement of the battery using an inherent ripple of the DC-DC conversion device in a low-current condition.
Optionally, the system 8000 further includes a switching device 860, and the conduction mode of the DC-DC conversion device 820 further includes a continuous conduction mode. The switching device 860 is configured to switch the DC-DC conversion device 820 to the discontinuous conduction mode or the critical conduction mode when one or more of the battery 810, the DC-DC conversion device 820, and the load 830 meet a predetermined criterion, and switch the DC-DC conversion device 820 to the continuous conduction mode when the criterion is not met. The calculation device 850 may be further configured to fuse the impedance spectra of the battery in the different conduction modes.
The predetermined criterion may be, for example, a current of the load 830 being less than a predetermined current threshold. For example, the current of the load 830 is less than the predetermined current threshold. Herein, the current threshold may be 0.2 A, 0.5 A, 1 A, or any other current values that can indicate that the system is in a low-current condition. In addition, the predetermined criterion may be alternatively the entire system being in any other suitable condition, for example, the battery 810 being in a purge phase.
Optionally, the system 8000 further includes a sending device 870. The sending device 870 is configured to send a second signal when the DC-DC conversion device 820 is in the critical conduction mode. The second signal indicates the load to be changed, so that a switching frequency of the DC-DC conversion device 820 changes. As mentioned above, “changing the load” is intended to mean changing parameters of the load 830, for example, a power, a voltage, a current, and any other parameters of the load 830 that can change the switching frequency of the DC-DC converter 820. In the critical conduction mode, since the switching frequency of the DC-DC converter 820 may vary with the load 830, an inherent ripple frequency of the DC-DC converter 820 may also vary accordingly, that is, measurement frequency of the battery 810 may vary accordingly.
In this regard, the measurement device 840 may be further configured to measure the output current values and the output voltage values of the battery 810 at different switching frequencies. The calculation device 850 may be further configured to calculate the impedance spectra of the battery 810 at the different switching frequencies based on the measured output current values and the measured output voltage values. Further, the calculation device 850 may be further configured to fuse the impedance spectra at the different switching frequencies.
Those skilled in the art can readily understand that the above system 8000 for impedance spectrum measurement of a battery can be incorporated into a vehicle. For example, the battery under test may be a vehicle-mounted battery, and the DC-DC conversion device may be a DC-DC converter that converts a high-voltage direct-current power of the vehicle-mounted battery into a low-voltage direct-current power required by a vehicle load. The system 8000 can implement an on-line test of an electrochemical impedance spectrum of the vehicle-mounted battery in a low-current condition by switching the conduction mode of the DC-DC converter configured between the battery and the load.
It should be understood that some of the block diagrams shown in the accompanying drawings of the present invention are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in the form of software, in one or more hardware modules or integrated circuits, or in different networks and/or processor apparatuses and/or micro-controller apparatuses.
It should also be understood that in some alternative embodiments, the functions/steps included in the above method may occur out of the order shown in the flowchart. For example, two functions/steps shown in sequence may be executed substantially simultaneously or even in a reverse order. This specifically depends on the functions/steps involved.
In conclusion, in the control solution for impedance spectrum measurement of a battery according to the embodiments of the present invention, it is possible to use an inherent ripple of the DC-DC converter to measure the impedance spectrum of the battery in a low-current condition by setting the conduction mode of the DC-DC converter, thereby effectively avoiding a problem of current reversal from the DC-DC converter to the battery. In addition, the control solution neither needs to add an additional harmonic power source to the battery or the DC-DC converter, nor needs to additionally control the DC-DC converter to generate harmonic disturbances. The control solution is simple to operate and easy to implement, and electrochemical impedance values of the battery at high frequencies can be measured.
Further, in the control solution for impedance spectrum measurement of a battery according to the embodiments of the present invention, the conduction mode of the DC-DC converter can be flexibly switched based on actual working conditions of the battery, the DC-DC converter, and the load. Still further, in the control solution for impedance spectrum measurement of a battery according to the embodiments of the present invention, a range of measurement frequencies can be changed by changing the load in the critical conduction mode, to obtain electrochemical impedance information of the battery in more frequency ranges.
Although only some of the implementations of the present invention have been described above in this specification, those of ordinary skill in the art should understand that the present invention can be implemented in many other forms without departing from its spirit and scope. Therefore, the presented examples and implementations are considered to be schematic rather than restrictive, and without departing from the spirit and scope of the present invention that are defined by the appended claims, the present invention may cover various changes and replacements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202111243951.8 | Oct 2021 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/078527 | 10/13/2022 | WO |
