Charging Control Method and Device, Battery Management System, Readable Storage Medium

Abstract

The present application provides a charging control method and device, a battery management system, and a readable storage medium. The charging control method includes: obtaining the battery temperature and battery state of charge; determining the pulse charging frequency based on the battery temperature, the battery state of charge, and a pre-calibrated correspondence; the pre-calibrated correspondence is the correspondence between the battery temperature, the battery state of charge, and the pulse charging frequency; obtaining the waveform characteristics of a preset pulse charging waveform; the waveform characteristics include: the ratio range of the area of the positive pulse waveform to the area of the negative pulse waveform in each pulse cycle of the pulse charging waveform; generating a charging request based on the pulse charging frequency and the waveform characteristics and sending it to the charging device. This method is used to improve the stability and safety of battery charging.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a charging control method and device, a battery management system, and a readable storage medium. Background Art

[0002] Pulse charging is a battery charging technology that uses pulse current to charge the battery. In existing technologies, pulse charging typically uses a bidirectional pulse current to charge the battery, and the pulse charging frequency is set to the battery's characteristic frequency. During the charging process, the battery's characteristic frequency varies with changes in battery temperature, and the pulse charging frequency is adjusted according to the battery's characteristic frequency until charging is complete.

[0003] The existing technical solution cannot effectively determine the pulse charging frequency and has potential safety hazards. Therefore, the stability and safety of battery charging are poor. Summary of the Invention

[0004] The purpose of this application is to provide a charging control method and device, a battery management system, and a readable storage medium to improve the stability and safety of battery charging.

[0005] In a first aspect, the present application provides a charging control method, comprising: obtaining a battery temperature and a battery state of charge; determining a pulse charging frequency based on the battery temperature, the battery state of charge, and a pre-calibrated correspondence; the pre-calibrated correspondence is a correspondence between the battery temperature, the battery state of charge, and the pulse charging frequency; obtaining waveform characteristics of a preset pulse charging waveform; the waveform characteristics include: a ratio range of the area of a positive pulse waveform to the area of a negative pulse waveform in each pulse period of the pulse charging waveform; generating a charging request based on the pulse charging frequency and the waveform characteristics and sending it to a charging device.

[0006] In this application, compared with the prior art, on the one hand, the correspondence between battery temperature, battery state of charge and pulse charging frequency is pre-calibrated. When the battery management system performs charging control, the real-time battery temperature and battery state of charge are first obtained. Then, based on the obtained battery temperature and state of charge and the corresponding relationship, the pulse charging frequency is determined, thereby effectively determining the pulse charging frequency. On the other hand, the waveform characteristics of the pulse charging waveform are preset, and the waveform characteristics include: the ratio range of the area of the positive pulse waveform to the area of the negative pulse waveform in each pulse cycle of the pulse charging waveform; by setting the lower limit of the ratio range, the normal progress of pulse charging can be ensured; by setting the upper limit of the ratio range, the safety hazard caused by lithium plating in the battery due to a large positive pulse can be avoided. In addition, the safety and stability of the pulse charging of the battery by the charging equipment are improved, and the impact of battery charging on battery performance is avoided.

[0007] As a possible implementation method, the waveform characteristics also include: a preset current peak value of the positive pulse waveform corresponding to the battery temperature and the battery state of charge, and a preset current peak value of the negative pulse waveform corresponding to the battery temperature and the battery state of charge; the current peak value of the negative pulse waveform is greater than the current peak value of the positive pulse waveform.

[0008] In this application, through research on charging pulse waveforms, it was found that: within a pulse cycle, if the current peak of the negative pulse waveform is greater than the current peak of the positive pulse waveform, when switching from positive pulse charging to negative pulse charging, the current peak increases, and the battery is less likely to experience lithium deposition and cell polarization. Therefore, by limiting the current peak of the negative pulse waveform to be greater than the current peak of the positive pulse waveform in the waveform characteristics, the safety of pulse charging can be improved and the impact on battery performance can be avoided.

[0009] As a possible implementation, the waveform feature further includes: a forward pulse waveform feature; the forward pulse waveform feature is expressed as: Wherein, F(t) represents the positive pulse waveform, is the area of the forward pulse waveform, t1 is the start time of the forward pulse waveform, t2 is the end time of the forward pulse waveform, I max+ is the peak current of the forward pulse waveform.

[0010] In the present application, the forward pulse waveform feature can be understood as the area of the forward pulse waveform being greater than half the area of the rectangular region corresponding to the forward pulse waveform. Through this forward pulse waveform feature, the maximum discharge current can be achieved by pulse charging.

[0011] As a possible implementation, the battery voltage corresponding to the current peak of the forward pulse waveform is lower than a pre-calibrated charge cut-off voltage, where the charge cut-off voltage is the decomposition voltage of the battery electrolyte or the breakdown voltage of the battery separator.

[0012] In this application, as the current increases, the voltage increases accordingly; the battery voltage corresponding to the current peak of the forward pulse waveform is the voltage upper limit, which can be limited by the charge cutoff voltage. The charge cutoff voltage is the decomposition voltage of the battery electrolyte or the breakdown voltage of the battery separator. These two voltages are higher than the conventional charge cutoff voltage and correspond to higher charging current peaks. Therefore, by determining these two voltages as the voltage upper limit, the peak value of the charging current can be increased, allowing the battery to complete charging as quickly as possible, thereby improving the battery's charging efficiency.

[0013] As a possible implementation manner, the frequency range of the pulse charging frequency in the pre-calibrated corresponding relationship is: 200 Hz-1500 Hz.

[0014] In this application, if the frequency is less than 200Hz, the battery is prone to lithium deposition, which in turn leads to capacity decay; 1500Hz can be understood as the maximum frequency that the charging device can reach; therefore, by limiting this frequency range, while ensuring the safety of battery charging and avoiding affecting battery performance, it ensures that the charging device can complete charging smoothly.

[0015] As a possible implementation manner, before determining the pulse charging frequency according to the battery temperature, the battery state of charge and a pre-calibrated correspondence, the charging control method also includes: determining whether the battery temperature is within a preset temperature range; determining the pulse charging frequency according to the battery temperature, the battery state of charge and a pre-calibrated correspondence includes: when it is determined that the battery temperature is within the preset temperature range, determining the pulse charging frequency according to the battery temperature, the battery state of charge and the pre-calibrated correspondence.

[0016] In the present application, when it is determined that the battery temperature is within a preset temperature range, the battery management system controls the battery to perform pulse charging, which is equivalent to the battery charging control strategy being able to be flexibly adjusted according to the temperature conditions, thereby improving the flexibility of battery charging.

[0017] As a possible implementation manner, the upper limit of the ratio range is 10, and the lower limit of the ratio is 1.

[0018] In this application, the lower limit of the ratio range is 1, which can ensure the normal progress of pulse charging; the upper limit of the ratio range is 10, which can avoid the safety hazard caused by battery lithium deposition due to too large a positive pulse.

[0019] In a second aspect, the present application provides a charging control device, comprising: functional modules for implementing the charging control method described in the first aspect and any possible implementation manner of the first aspect.

[0020] In a third aspect, the present application provides a battery management system comprising: a processor; and a memory communicatively connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor can execute the charging control method described in the first aspect and any possible implementation of the first aspect.

[0021] In a fourth aspect, the present application provides a readable storage medium having a computer program stored thereon. When the computer program is executed by a computer, the charging control method as described in the first aspect and any possible implementation of the first aspect is executed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0023] Figure 1 is a schematic diagram of a charging system disclosed in one embodiment of the present application;

[0024] Figure 2 This is a flow chart of a charging control method disclosed in one embodiment of the present application;

[0025] Figure 3 This is an example diagram of a pulse charging waveform disclosed in an embodiment of the present application;

[0026] Figure 4 This is an example diagram of a pulse charging waveform disclosed in another embodiment of the present application;

[0027] Figure 5 This is a structural diagram of a charging control device disclosed in one embodiment of the present application;

[0028] Figure 6 This is a schematic structural diagram of a battery management system disclosed in one embodiment of the present application.

[0029] In the drawings, the drawings are not drawn to scale.

[0030] Description of the markings: 10 - charging system; 11 - charging device; 12 - battery management system; 120 - processor; 121 - memory; 122 - communication module; 500 - charging control device; 510 - acquisition module; 520 - processing module. DETAILED DESCRIPTION

[0031] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0032] In the description of this application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly perpendicular, but is within the allowable error range. "Parallel" is not strictly parallel, but is within the allowable error range.

[0033] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of this application. In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0034] Please refer to Figure 1 , which is a schematic diagram of a charging system 10 according to an embodiment of the present application, includes a charging device 11, a battery management system 12, and a battery. When charging the battery via the charging device 11, the charging device 11 and the battery management system 12 are in communication connection, the charging device 11 and the battery are electrically connected, and the battery management system 12 and the battery are electrically connected.

[0035] The charging device 11 may be in the form of a charging pile, a charging box, a charging cabinet, etc. The charging device 11 may include a DC charging module and a pulse charging module, that is, the charging device 11 can implement both DC charging and pulse charging.

[0036] The battery management system 12 is used to manage the battery, such as various parameters such as the battery's SOC (State of Charge), battery capacity, and battery temperature; another example is to control the battery's charging. Therefore, the hardware environment used in the charging control method provided in the embodiments of the present application can be the battery management system 12 corresponding to the battery.

[0037] The hardware environment of the battery system composed of the battery management system 12 and the battery can be an electric vehicle or other electric device that uses a power battery as a power source, such as an electric car, an electric motorcycle, etc. Therefore, the charging control method provided in the embodiment of the present application can be applied to various electric devices.

[0038] The battery can be various types of lithium batteries, such as lithium iron phosphate batteries, lithium iron sulfide batteries, etc.

[0039] When the charging device 11 and the battery management system 12 are in communication, charging messages can be exchanged between the charging device 11 and the battery management system 12. For example, the battery management system 12 transmits corresponding charging information to the charging device 11 in the form of a charging message, and the charging device 11 charges the battery based on the charging information in the received charging message.

[0040] Before charging begins, the battery management system 12 and the charging device 11 can exchange charging messages. During the charging process, these messages can continue to be exchanged between the battery management system 12 and the charging device 11, allowing adjustments to be made to the charging information and the battery's charging strategy. For example, the pulse charging frequency and waveform can be adjusted.

[0041] Based on the introduction of the above application scenarios, please refer to Figure 2 , is a flow chart of a charging control method provided in an embodiment of the present application, which can be applied to the battery management system 12, including:

[0042] Step 210: Obtain battery temperature and battery SOC.

[0043] Step 220: Determine the pulse charging frequency based on the battery temperature, the battery SOC, and a pre-calibrated corresponding relationship, wherein the pre-calibrated corresponding relationship is the corresponding relationship between the battery temperature, the battery SOC, and the pulse charging frequency.

[0044] Step 230: Obtaining the waveform characteristics of the preset pulse charging waveform, wherein the waveform characteristics include: the ratio range of the area of the positive pulse waveform to the area of the negative pulse waveform in each pulse cycle of the pulse charging waveform.

[0045] Step 240 : Generate a charging request based on the pulse charging frequency and waveform characteristics and send it to the charging device 11 .

[0046] The charging control method provided in the embodiment of the present application is adopted. On the one hand, the correspondence between the battery temperature, the battery SOC and the pulse charging frequency is pre-calibrated. When the battery management system 12 performs charging control, the real-time battery temperature and battery SOC are first obtained. Then, based on the obtained battery temperature and battery SOC and the correspondence, the pulse charging frequency is determined to achieve effective determination of the pulse charging frequency. On the other hand, the waveform characteristics of the pulse charging waveform are preset, and the waveform characteristics include: the ratio range of the area of the positive pulse waveform to the area of the negative pulse waveform in each pulse cycle of the pulse charging waveform; by setting the lower limit of the ratio range, the normal progress of the pulse charging can be ensured; by setting the upper limit of the ratio range, the safety hazard caused by the lithium deposition of the battery due to the positive pulse being too large can be avoided. In addition, the safety and stability of the pulse charging of the battery by the charging device 11 are improved, and the impact of battery charging on the battery performance is avoided.

[0047] Next, the detailed implementation of the charging control method is introduced.

[0048] In step 210, the battery management system 12 may acquire the battery temperature through a temperature acquisition module within the battery information acquisition module. The temperature acquisition module may be a thermistor, temperature sensor, or the like. The battery management system 12 may also acquire information such as the battery voltage, current, and power through a voltage, current, and power acquisition module within the acquisition module. Based on the acquired information, the battery SOC is estimated to acquire the battery SOC.

[0049] It can be understood that for a battery, the battery status information includes: battery temperature, battery SOC, voltage, current, etc.; correspondingly, for the battery management system 12, in addition to obtaining battery temperature and battery SOC, other battery status information, such as battery voltage, current, etc., can also be obtained when necessary.

[0050] In step 220 , the correspondence between the battery temperature, the battery SOC, and the pulse charging frequency may be calibrated offline. The implementation of the offline calibration will be described below.

[0051] During offline calibration, the relationship between cell impedance and frequency is utilized. This relationship can be represented by a cell impedance-frequency curve (graph). The horizontal axis of this curve represents the frequency of the AC signal, and the vertical axis represents the cell anode AC impedance, which is divided into the real and imaginary parts of the impedance. As the frequency of the AC signal increases, the cell anode AC impedance gradually decreases.

[0052] The process of determining the correspondence between frequency and temperature based on the cell impedance-frequency curve includes: for the same cell, under different temperature conditions and different cell capacities, multiple real and imaginary part curves are drawn to obtain the curve functions of the real and imaginary parts respectively. Then, the curve function is differentiated once. When the derivative is negative and the derivative is less than a preset threshold for the first time, the frequency corresponding to the derivative (the horizontal axis value) is the minimum value of the pulse current frequency.

[0053] In the above process, under the same temperature condition, corresponding pulse current frequencies can be obtained for different SOC intervals, thereby obtaining pulse current frequencies for different SOC intervals under the same temperature condition.

[0054] For example, assuming there are 4 imaginary part curves, 4 corresponding frequency values can be obtained at the same temperature and different SOC ranges.

[0055] In the embodiment of the present application, when calibrating the corresponding relationship, the pulse charging frequency can also be limited to a fixed frequency range.

[0056] Through the battery cell impedance-frequency curve, it is found that when the pulse charging frequency is greater than a certain value, the effective values of the real and imaginary parts of the impedance are greatly reduced. Therefore, within a certain range, the greater the pulse charging current frequency, the less likely the battery cell is to deposit lithium.

[0057] Therefore, the lower limit of the fixed frequency range can be set based on the frequency at which the effective values of the real and imaginary impedance parts begin to decrease significantly. Taking a 173Ah lithium iron phosphate battery cell as an example, when the pulse charging frequency exceeds 195Hz, the effective values of the real and imaginary impedance parts decrease significantly. Therefore, the lower limit of the frequency range corresponding to this battery cell can be a frequency slightly greater than 195Hz, for example: 200Hz.

[0058] Since the battery capacity will decrease accordingly when lithium plating occurs, in addition to the above embodiment, a conventional battery charge and discharge capacity test can also be performed at room temperature. When the battery capacity decreases compared to the normal battery capacity, the corresponding frequency value can be determined as the lower limit of the frequency range.

[0059] As a pulse current generator, the charging device 11 has a limited pulse charging frequency. If the pulse charging frequency is too high, the charging device 11 may not be able to provide the corresponding pulse charging current. Therefore, the upper limit of the fixed frequency range can be set according to the charging device 11.

[0060] As an optional implementation, a frequency upper limit value applicable to most charging devices 11 may be directly preset in the battery management system 12 .

[0061] As another optional implementation, the battery management system 12 may exchange messages with the charging device 11 so that the battery management system 12 determines the maximum pulse charging frequency that the charging device 11 can accept.

[0062] For example, the battery management system 12 provides several optional maximum pulse charging frequencies to the charging device 11. The charging device 11 then determines a maximum pulse charging frequency that suits it and sends it to the battery management system 12. Another example is that the charging device 11 proactively transmits its acceptable maximum pulse charging frequency to the battery management system 12.

[0063] In the embodiment of the present application, an optional pulse charging frequency range is provided: 200 Hz-1500 Hz. This pulse charging frequency range can be applied to lithium iron phosphate batteries and most charging devices 11.

[0064] By limiting the frequency range, it is possible to ensure that the charging safety of the battery is guaranteed, avoid affecting the battery performance, and ensure that the charging device 11 can successfully complete the charging.

[0065] Please refer to Table 1, which is an example of the correspondence between battery temperature, battery SOC and pulse charging frequency provided in an embodiment of the present application. It can be understood that the correspondence shown in Table 1 is only an example and does not constitute a limitation on the embodiment of the present application.

[0066] Table 1 shows four SOC ranges for each temperature condition, each corresponding to a pulse charging frequency. Based on this correspondence and the real-time battery temperature and SOC, the pulse charging frequency can be determined. For example, if the battery temperature is -16°C and the battery SOC is 40%, the pulse charging frequency is 1400Hz. If the battery temperature is 2°C, the pulse charging frequency remains 300Hz regardless of the battery SOC.

[0067] Table 1

[0068]

[0069]

[0070] In step 230, the battery management system 12 obtains a preset waveform feature of the pulse charging waveform, which includes the ratio range of the area of the positive pulse waveform to the area of the negative pulse waveform in each pulse cycle of the pulse charging waveform.

[0071] For easier understanding, please refer to Figure 3 and Figure 4 , are two examples of pulse charging waveforms for one pulse cycle provided in this application. Figure 3 and Figure 4 In the figure, the waveform function is F(t). The pulse charging waveform during the period t1-t2 is a positive pulse waveform, and the pulse charging waveform during the period t2-t3 is a negative pulse waveform. t1-t3 is one pulse cycle. Accordingly, the area of region S1 is the area of the positive pulse waveform, and the area of region S2 is the area of the negative pulse waveform.

[0072] Combine Figure 3 and Figure 4 For example, the waveform characteristics above can be expressed as: A ≤ S1 / S2 ≤ B. By setting the upper limit (B) of this ratio range, we can avoid the safety hazard of excessive positive pulses and lithium deposition in the battery. By setting the lower limit (A) of this ratio range, we can ensure normal pulse charging.

[0073] Combining the upper and lower limits of the ratio range, when the ratio range is preset, the lower limit of the ratio range can be determined based on the minimum area ratio that ensures pulse charging. The upper limit of the ratio range can be determined by offline testing the battery lithium deposition corresponding to different area ratios to determine the upper limit of the area ratio at which battery lithium deposition does not occur.

[0074] As an optional implementation, the ratio range may be 1-10, then the above waveform characteristics are expressed as: 1≤S1 / S2≤10.

[0075] In addition to the possibility that excessive positive pulses may cause lithium deposition in batteries, other reasons may also cause lithium deposition in batteries. Therefore, more limiting conditions can be included in the waveform characteristics.

[0076] Through research on charging pulse waveforms, it was found that: within a pulse cycle, if the current peak of the negative pulse waveform is greater than the current peak of the positive pulse waveform, when the positive pulse charging is switched to the negative pulse charging, the current peak increases, and the battery is less likely to experience lithium deposition and cell polarization. Therefore, as an optional embodiment, the waveform characteristics also include: a preset current peak of the positive pulse waveform corresponding to the battery temperature and battery state of charge, and a preset current peak of the negative pulse waveform corresponding to the battery temperature and battery state of charge; and the current peak of the negative pulse waveform is greater than the current peak of the positive pulse waveform.

[0077] In this embodiment, assuming that the preset value of the current peak of the positive pulse waveform is M, and the preset value of the current peak of the negative pulse waveform is N, then, at different temperatures, M may be different, N may also be different, but N is always greater than M; at the same temperature, the battery SOC may be different, M may be different, N may also be different, but N is always greater than M.

[0078] As an optional implementation, the pre-calibrated corresponding relationship can be, in addition to the relationship between battery temperature, battery state of charge and pulse charging frequency, the relationship between battery temperature, battery state of charge, pulse charging frequency, the current peak value of the positive pulse waveform and the current peak value of the negative pulse waveform.

[0079] If this embodiment is adopted, after the pulse charging frequency is determined based on the corresponding relationship in step 220, the current peak value of the corresponding positive pulse waveform and the current peak value of the negative pulse waveform are determined in combination with the corresponding relationship.

[0080] As another optional implementation, the relationship between the battery temperature and battery state of charge and the current peak value of the positive pulse waveform and the current peak value of the negative pulse waveform can also be pre-calibrated. In step 230, the current peak value of the positive pulse waveform and the current peak value of the negative pulse waveform are determined in combination with the corresponding relationship and the real-time battery temperature and the real-time battery state of charge.

[0081] It can be understood that during the pulse charging process, as the pulse current increases, the battery voltage also increases accordingly. The battery voltage corresponding to the current peak of the forward pulse waveform is the voltage upper limit. The battery voltage upper limit can be calibrated by the charging cut-off voltage. Then, the battery voltage corresponding to the current peak of the forward pulse waveform is less than the pre-calibrated charging cut-off voltage.

[0082] The charge cut-off voltage is the decomposition voltage of the battery electrolyte or the breakdown voltage of the battery separator. Both the decomposition voltage and the breakdown voltage can be determined through offline testing.

[0083] Based on the pre-calibrated charging cut-off voltage, the voltage upper limit can be determined, and then based on the positive correlation between voltage and current, the current peak of the forward pulse waveform can be determined.

[0084] In conventional DC charging, if the current is too large, ions will transfer rapidly, causing the polarization voltage to quickly reach its peak value, and the battery will quickly reach a fully charged state, and the battery will no longer be able to charge. However, the embodiments of the present application use pulse charging, which is provided with a pulse charging cycle. Within a pulse charging cycle, based on positive and negative pulses, the transfer of ions is back and forth. Excessive current will not cause the polarization voltage to reach its peak value. Therefore, in pulse charging, the current peak value can be as large as possible.

[0085] In the embodiments of the present application, the decomposition voltage of the battery electrolyte or the breakdown voltage of the battery separator is selected as the charge cutoff voltage. These two voltages are higher than conventional charge cutoff voltages (such as the charge cutoff voltage of DC charging), and the corresponding charging current peak is also higher. Therefore, by determining these two voltages as the voltage upper limit, the peak charging current can be increased, allowing the battery to complete charging as quickly as possible, thereby improving the battery's charging efficiency.

[0086] For the current peak of the negative pulse waveform, the corresponding battery voltage is greater than the pre-calibrated discharge cut-off voltage. The discharge cut-off voltage here is a conventional discharge cut-off voltage and does not need to be combined with specific battery characteristics for offline testing. It is not introduced in detail in the embodiments of this application.

[0087] Based on Table 1, please refer to Table 2, which provides an example of the correspondence between the battery temperature, battery SOC, pulse charging frequency, current peak value of the positive pulse waveform, and current peak value of the negative pulse waveform provided in the embodiment of the present application. It can be understood that the correspondence shown in Table 2 is only an example and does not constitute a limitation on the embodiments of the present application.

[0088] In Table 2, under each temperature condition, there are 4 SOC intervals, and each SOC interval corresponds to a positive current peak (i.e., the current peak of the positive pulse waveform) and a negative current peak (i.e., the current peak of the negative pulse waveform). Based on this correspondence, and the real-time acquired battery temperature and battery state of charge, the positive current peak and negative current peak can be determined. For example: assuming the battery temperature is -16°C and the battery SOC is 40%, the positive current peak is 0.05C (C represents coulomb, as a unit), and the negative current peak is 0.1C. Assuming the battery temperature is 2°C and the battery SOC is 80%, the positive current peak is 0.3C and the negative current peak is 1.2C.

[0089] Table 2

[0090]

[0091] In order to ensure that the pulse charging can achieve the maximum discharge current, the area of the positive pulse waveform should be as large as possible. Based on this characteristic, the waveform characteristics can also include: positive pulse waveform characteristics. Figure 3 and Figure 4 For example, the positive pulse waveform characteristics are expressed as: Where F(t) represents the positive pulse waveform, is the area of the forward pulse waveform, t1 is the start time of the forward pulse waveform, t2 is the end time of the forward pulse waveform, I max+ is the peak current of the forward pulse waveform.

[0092] The forward pulse waveform feature can be understood as the area of the forward pulse waveform being greater than half the area of the rectangular region corresponding to the forward pulse waveform. Figure 3 In , the area of the positive pulse waveform is equal to the area of the rectangular region corresponding to the positive pulse waveform, which meets this condition. Figure 4 In the example, the area of the positive pulse waveform is greater than half of the area of the matrix region corresponding to the positive pulse waveform, which also meets this condition.

[0093] After the above-mentioned waveform characteristics and pulse charging frequency are determined, the duty cycle of the pulse charging waveform (determined by the pulse charging frequency), the positive pulse current amplitude, the negative pulse current amplitude, the ratio of the effective values of the positive and negative pulses (areas), the cut-off voltage of the positive and negative pulses of the battery, and other information are also limited accordingly.

[0094] In practical applications, the waveform characteristics may include at least one of the above-mentioned waveform characteristics, namely, at least one of the positive-negative pulse area ratio, positive pulse current amplitude, negative pulse current amplitude, and positive pulse waveform characteristics.

[0095] Although the waveform characteristics are limited, the waveform shape of the pulse charging waveform is not limited. Whether it is a positive pulse or a negative pulse, as long as the waveform characteristics are met, it can be: square wave, trapezoidal wave, sine wave, etc., or it can be a distortion or superposition of these waveforms, and is not limited to a specific waveform.

[0096] Furthermore, in step 240, when generating a charging request based on the pulse charging frequency and waveform characteristics, the charging request may include: the pulse charging frequency and waveform characteristics; may also include: some optional waveform shapes; and may also include: battery temperature.

[0097] Since each of the aforementioned waveform characteristics has a corresponding effect on improving the lithium deposition risk of the battery, the waveform characteristics can be flexibly limited based on the actual lithium deposition risk of the battery. The lithium deposition risk of the battery can be roughly judged in combination with the battery temperature.

[0098] The waveform characteristics in the charging request may be specified waveform characteristics determined by the battery management system 12 based on the current battery temperature. For example, when the current battery temperature is low, the waveform characteristics may include: positive-to-negative pulse area ratio, positive pulse current amplitude, negative pulse current amplitude, and positive pulse waveform characteristics. When the current battery temperature is normal, the waveform characteristics may include one to three waveform characteristics, such as: positive-to-negative pulse area ratio, positive pulse current amplitude, and negative pulse current amplitude.

[0099] The charging request may also include the aforementioned waveform characteristics: positive-to-negative pulse area ratio, positive pulse current amplitude, negative pulse current amplitude, and positive pulse waveform characteristics; and the battery temperature. In this embodiment, the battery management system 12 feeds back each determined waveform characteristic to the charging device 11, which then determines a waveform characteristic that matches the battery temperature based on the battery temperature. This determination method can be similar to the aforementioned embodiment in which the battery management system 12 determines a specific waveform characteristic based on the battery temperature.

[0100] Furthermore, for the charging device 11, after receiving the charging request, it generates a corresponding pulse charging current according to each charging information in the charging request to perform pulse charging for the battery.

[0101] As an optional implementation, based on the pulse charging frequency in the charging request, the frequency of the pulse charging waveform finally output by the charging device 11 may be equal to the pulse charging frequency, or may be a frequency higher than the pulse charging frequency.

[0102] Pulse charging technology works better when applied to a lower battery temperature. Therefore, in actual application, if the charging device 11 has both a DC charging module and a pulse charging module, pulse charging and DC charging can be flexibly adjusted.

[0103] As an optional implementation, before step 240 , the method further includes: determining whether the battery temperature is within a preset temperature range; and executing step 240 when it is determined that the battery temperature is within the preset temperature range.

[0104] In this embodiment, the preset temperature range is equivalent to the condition of the pulse charging mode. When the temperature is within the preset temperature range, pulse charging is adopted; when the temperature is not within the preset temperature range, conventional DC charging can be adopted.

[0105] The preset temperature range may be, for example, (-∞, 5°C), that is, when the battery temperature is less than or equal to 5°C, pulse charging is adopted; when the battery temperature is greater than 5°C, DC charging is adopted.

[0106] Through this implementation, the battery charging control strategy can be flexibly adjusted according to temperature conditions, thereby improving the flexibility of battery charging.

[0107] It is understandable that the battery can also be pulse charged throughout the entire process until the battery is fully charged, but the frequency of pulse charging will change accordingly with changes in battery temperature through charging control of the battery management system 12.

[0108] In the embodiments of the present application, both the pre-calibrated correspondence and the waveform characteristics of the preset pulse charging waveform are pre-calibrated. Using this calibration information, the battery can be charged at low temperatures and the impact of pulse charging on battery performance can be avoided. However, this pre-calibrated information may not take into account the impact of other factors on the battery during use, such as inaccurate SOC estimation and battery wear and tear. The battery charging effect is better when the battery is in use for a short time, but may be less than ideal if the battery is in use for a long time.

[0109] Therefore, considering the impact of other factors on the battery during use, the embodiment of the present application provides two implementation methods for updating the pre-calibrated correspondence and the preset waveform characteristics.

[0110] A first optional implementation method is to update the pulse charging frequency in the corresponding relationship through interaction with the charging device 11. Specifically, before each charging, the battery management system 12 requests the charging device 11 for the maximum pulse charging frequency that the charging device 11 can output (which can be understood as the actual maximum pulse charging frequency), and compares the actual maximum pulse charging frequency with the maximum pulse charging frequency in the corresponding relationship (which can be understood as the theoretical maximum pulse charging frequency). If the actual maximum pulse charging frequency is greater than or equal to the theoretical maximum pulse charging frequency, there is no need to update the various pulse charging frequencies in the corresponding relationship. If the actual maximum pulse charging frequency is less than the theoretical maximum pulse charging frequency, then the various pulse charging frequencies in the corresponding relationship are reduced by a preset amount. The preset amount can be the difference between the actual maximum pulse charging frequency and the theoretical maximum pulse frequency.

[0111] A correspondence between the number of battery charge cycles and the amplitude loss is preset for the positive and negative pulse amplitudes. The battery management system 12 records the number of battery charge cycles. For example, after each full charge, the number of battery charge cycles is incremented by 1, with the initial value of the battery charge cycle set to 0. After the battery charge cycle reaches the corresponding number of charge cycles in the correspondence, the corresponding amplitude loss is subtracted from the original positive and negative pulse amplitudes.

[0112] The positive pulse waveform characteristics and the ratio range of the positive and negative pulse areas in the waveform characteristics generally do not change with changes in battery performance and therefore do not need to be updated.

[0113] In a second optional embodiment, after each full charge, the battery management system 12 records the maximum SOC that the battery can reach. When the maximum SOC that the battery can reach is less than a preset SOC, a corresponding prompt message is output, which is used to instruct the pre-calibrated correspondence and waveform characteristics to be updated.

[0114] In this embodiment, the battery management system 12 assesses battery wear based on changes in SOC and prompts an update based on the battery wear. After the user receives the prompt, the battery can be recalibrated offline to update the pre-calibrated correspondence and waveform characteristics.

[0115] In actual applications, other feasible implementation methods may also be adopted to update the pre-calibrated correspondence and waveform characteristics, which are not limited in the embodiments of the present application.

[0116] Based on the same invention concept, please refer to Figure 5 In an embodiment of the present application, a charging control device 500 is further provided, including: an acquisition module 510 and a processing module 520.

[0117] The acquisition module 510 is used to obtain the battery temperature and battery state of charge. The processing module 520 is used to determine the pulse charging frequency based on the battery temperature, the battery state of charge, and a pre-calibrated correspondence; the pre-calibrated correspondence is the correspondence between the battery temperature, the battery state of charge, and the pulse charging frequency. The acquisition module 510 is also used to obtain the waveform characteristics of a preset pulse charging waveform; the waveform characteristics include: the ratio range of the area of the positive pulse waveform to the area of the negative pulse waveform in each pulse cycle of the pulse charging waveform. The processing module 520 is also used to generate a charging request based on the pulse charging frequency and the waveform characteristics and send it to the charging device 11.

[0118] In an embodiment of the present application, the processing module 520 is also used to: determine whether the battery temperature is within a preset temperature range; and specifically to: when it is determined that the battery temperature is within the preset temperature range, determine the pulse charging frequency according to the battery temperature, the battery state of charge and a pre-calibrated correspondence.

[0119] The charging control device 500 corresponds to the charging control method described in the aforementioned embodiment, and each functional module corresponds one-to-one to each step of the charging control method. Therefore, the implementation of each functional module refers to the implementation of the charging control method and will not be repeated here.

[0120] Based on the same invention concept, please refer to Figure 6 In an embodiment of the present application, a battery management system 12 is further provided, including: a processor 120, a memory 121, and a communication module 122.

[0121] The processor 120, memory 121, and communication module 122 are electrically connected, directly or indirectly, to enable data transmission or interaction. For example, these components may be electrically connected via one or more communication buses or signal buses. Each charging control method includes at least one software functional module that can be stored in the memory 121 in the form of software or firmware.

[0122] The processor 120 can be an integrated circuit chip with signal processing capabilities. The processor 120 can be a general-purpose processor, including a CPU (Central Processing Unit), an NP (Network Processor), etc.; it can also be a digital signal processor, an application-specific integrated circuit, an off-the-shelf programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor.

[0123] The memory 121 can store various software programs and modules, such as the program instructions / modules corresponding to the charging control method and apparatus provided in the embodiments of the present application. The processor 120 executes the software programs and modules stored in the memory 121 to perform various functional applications and data processing, thereby implementing the technical solutions in the embodiments of the present application.

[0124] The memory 121 may include but is not limited to RAM (Random Access Memory), ROM (Read Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electric Erasable Programmable Read-Only Memory), etc.

[0125] The communication module 122 is used to realize the communication connection between the battery management system 12 and the charging device 11, which can be: a wireless communication module, a Bluetooth communication module, a 4G / 5G communication module, etc.

[0126] I understand. Figure 6 The components shown are only examples, and the battery management system 12 may also include more components, such as a temperature acquisition module.

[0127] In an embodiment of the present application, an electric vehicle is further provided, comprising: a power battery and Figure 6 The battery management system 12 shown also includes a vehicle controller and other basic structures or components of an electric vehicle.

[0128] In an embodiment of the present application, a readable storage medium is further provided, on which a computer program is stored. When the computer program is executed by a computer, the charging control method provided in the embodiment of the present application is executed.

[0129] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A charging control method, characterized in that: include: Get battery temperature and battery state of charge; determining a pulse charging frequency according to the battery temperature, the battery state of charge, and a pre-calibrated corresponding relationship; The pre-calibrated corresponding relationship is the corresponding relationship between battery temperature, battery state of charge and pulse charging frequency; Obtaining waveform characteristics of a preset pulse charging waveform; The waveform characteristics include: a ratio range of the area of the positive pulse waveform to the area of the negative pulse waveform in each pulse cycle of the pulse charging waveform; the upper limit of the ratio range is 10, and the lower limit of the ratio range is 1; A charging request is generated according to the pulse charging frequency and the waveform characteristics and sent to a charging device.

2. The charging control method according to claim 1, wherein: The waveform characteristics also include: a preset current peak value of the positive pulse waveform corresponding to the battery temperature and the battery state of charge, and a preset current peak value of the negative pulse waveform corresponding to the battery temperature and the battery state of charge; the current peak value of the negative pulse waveform is greater than the current peak value of the positive pulse waveform.

3. The charging control method according to claim 2, wherein: The waveform characteristics also include: a forward pulse waveform characteristic; the forward pulse waveform characteristic is expressed as: Wherein, F(t) represents the positive pulse waveform, is the area of the forward pulse waveform, t1 is the start time of the forward pulse waveform, t2 is the end time of the forward pulse waveform, I max+ is the peak current of the forward pulse waveform.

4. The charging control method according to claim 2 or 3, characterized in that: The battery voltage corresponding to the current peak of the forward pulse waveform is less than a pre-calibrated charge cut-off voltage, and the charge cut-off voltage is the decomposition voltage of the battery electrolyte or the breakdown voltage of the battery separator.

5. The charging control method according to any one of claims 1 to 3, characterized in that: The frequency range of the pulse charging frequency in the pre-calibrated corresponding relationship is: 200Hz-1500Hz.

6. The charging control method according to any one of claims 1 to 3, characterized in that: Before determining the pulse charging frequency according to the battery temperature, the battery state of charge, and a pre-calibrated corresponding relationship, the charging control method further includes: determining whether the battery temperature is within a preset temperature range; The determining of the pulse charging frequency according to the battery temperature, the battery state of charge, and a pre-calibrated corresponding relationship includes: When it is determined that the battery temperature is within the preset temperature range, the pulse charging frequency is determined according to the battery temperature, the battery state of charge, and a pre-calibrated corresponding relationship.

7. A charging control device, characterized in that: include: An acquisition module is used to obtain battery temperature and battery state of charge; a processing module, configured to determine a pulse charging frequency based on the battery temperature, the battery state of charge, and a pre-calibrated correspondence relationship; the pre-calibrated correspondence relationship being a correspondence relationship between the battery temperature, the battery state of charge, and the pulse charging frequency; The acquisition module is also used to obtain the waveform characteristics of a preset pulse charging waveform; the waveform characteristics include: the ratio range of the area of the positive pulse waveform to the area of the negative pulse waveform in each pulse cycle of the pulse charging waveform; the upper limit of the ratio range is 10, and the lower limit of the ratio range is 1; the processing module is also used to generate a charging request based on the pulse charging frequency and the waveform characteristics and send it to the charging device.

8. The charging control device according to claim 7, characterized in that: The waveform characteristics also include: a preset current peak value of the positive pulse waveform corresponding to the battery temperature and the battery state of charge, and a preset current peak value of the negative pulse waveform corresponding to the battery temperature and the battery state of charge; the current peak value of the negative pulse waveform is greater than the current peak value of the positive pulse waveform.

9. The charging control device according to claim 8, characterized in that: The waveform characteristics also include: a forward pulse waveform characteristic; the forward pulse waveform characteristic is expressed as: Wherein, F(t) represents the positive pulse waveform, is the area of the forward pulse waveform, t1 is the start time of the forward pulse waveform, t2 is the end time of the forward pulse waveform, I max+ is the peak current of the forward pulse waveform.

10. The charging control device according to claim 8 or 9, characterized in that: The battery voltage corresponding to the current peak of the forward pulse waveform is less than a pre-calibrated charging cut-off voltage.

11. The charging control device according to any one of claims 7 to 9, characterized in that: The frequency range of the pulse charging frequency in the pre-calibrated corresponding relationship is: 200Hz-1500Hz.

12. The charging control device according to any one of claims 7 to 9, characterized in that: The processing module is further configured to: determine whether the battery temperature is within a preset temperature range; And specifically used for: when it is determined that the battery temperature is within the preset temperature range, determining the pulse charging frequency according to the battery temperature, the battery state of charge and a pre-calibrated corresponding relationship.

13. A battery management system, characterized in that: include: processor; and a memory communicatively connected to the processor; The memory stores instructions that can be executed by the processor, and the instructions are executed by the processor to enable the processor to execute the charging control method according to any one of claims 1 to 6.

14. A readable storage medium, characterized in that The readable storage medium stores a computer program, and when the computer program is executed by a computer, the charging control method according to any one of claims 1 to 6 is executed.

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