CN114290958B - A battery low temperature pulse charging method and device - Google Patents

Abstract

The invention provides a battery low-temperature pulse charging method and a device, which are characterized in that in the charging process of a battery pack, the battery pack is subjected to instant pulse discharge for a reverse time period, and then is charged, the whole process is a bidirectional pulse charging process, the charging method has obvious effect on inhibiting the lithium precipitation phenomenon, the polarization phenomenon in the battery charging process can be relieved, the charging acceptance of the battery is improved, no additional equipment is required to be added for heating the battery pack, and the waste of resources is reduced.

Description

A battery low temperature pulse charging method and device

Technical Field

The present invention relates to the technical field of new energy vehicles, and in particular to a method and device for low-temperature pulse charging of a battery.

Background Art

In the context of energy demand and carbon emission requirements, new energy vehicles, especially electric vehicles, have become an important development direction for future vehicles. Among them, the main power system of electric vehicles is the battery pack, such as the lithium-ion power battery pack. However, the lithium-ion power battery pack is prone to lithium deposition when charging in a low-temperature environment, making it difficult to charge the lithium-ion power battery pack and reducing safety.

Summary of the invention

In view of this, an embodiment of the present invention provides a battery low-temperature pulse charging method and device to achieve safe charging of a battery pack.

To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

A battery low-temperature pulse charging method is applied to a control module of a battery charging system, wherein the battery charging system comprises a charging pile and the control module, and the method comprises:

Determining a maximum discharge current of a battery pack, the battery pack comprising a plurality of battery cells, one of the battery cells being a reference battery cell having a built-in reference electrode;

Controlling the battery pack to discharge to the charging pile at the maximum discharge current for a first preset time period;

When the discharge is completed, the charging pile is controlled to charge the battery pack. When the potential of the negative electrode of the reference battery cell relative to the reference electrode reaches a preset threshold potential, the step of controlling the battery pack to discharge to the charging pile with the maximum discharge current for a first preset time period is returned to execute until the terminal voltage of the reference battery cell reaches the charging cut-off voltage.

Optionally, determining the maximum discharge current of the battery pack includes:

The battery pack is discharged for a second preset time period using the initial discharge current as the discharge current, the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is calculated, and it is determined whether the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within an allowable difference range; if it is beyond the allowable difference range, the discharge current is increased and the process returns to the step of discharging the battery pack for the second preset time period until the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range; the discharge current when the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range is used as the maximum discharge current.

Optionally, increase the discharge current, including:

Increase the discharge current based on a preset step size.

Optionally, charging the battery pack includes:

The battery pack is charged with a standard battery charging current.

Optionally, also include:

When the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within an allowable difference range, taking the temperature of the battery pack as a reference temperature;

Obtaining the real-time temperature of the battery pack;

Determining whether the difference between the reference temperature and the real-time temperature of the battery pack is greater than a preset temperature threshold;

When the difference between the reference temperature and the real-time temperature of the battery pack is greater than a preset temperature threshold, the maximum discharge current of the battery pack is re-determined.

A battery low-temperature pulse charging device is applied to a control module of a battery charging system. The battery charging system includes a charging pile and the control module. The device includes:

a maximum discharge current determination unit, used to determine a maximum discharge current of a battery pack, wherein the battery pack includes a plurality of battery cells, one of which is a reference battery cell having a built-in reference electrode;

A discharge control unit, used for controlling the battery pack to discharge to the charging pile at the maximum discharge current for a first preset time period;

The charging unit is used to control the charging pile to charge the battery pack after the discharge is completed, and trigger the discharge control unit when the potential of the negative electrode of the reference battery cell relative to the reference electrode reaches a preset threshold potential, and stop charging the battery pack when the terminal voltage of the reference battery cell reaches a charging cut-off voltage.

Optionally, when determining the maximum discharge current of the battery pack, the maximum discharge current determination unit is specifically used to:

The battery pack is discharged for a second preset time period using the initial discharge current as the discharge current, the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is calculated, and it is determined whether the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within an allowable difference range; if it is beyond the allowable difference range, the discharge current is increased and the process returns to the step of discharging the battery pack for the second preset time period until the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range; the discharge current when the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range is used as the maximum discharge current.

A charging system, comprising: a charging pile and a control module;

The charging pile is a charging pile with battery charging and discharging functions;

The control module is specifically used for:

Determining a maximum discharge current of a battery pack, the battery pack comprising a plurality of battery cells, one of the battery cells being a reference battery cell having a built-in reference electrode;

Controlling the battery pack to discharge to the charging pile at the maximum discharge current for a first preset time period;

When the discharge is completed, the charging pile is controlled to charge the battery pack. When the potential of the negative electrode of the reference battery cell relative to the reference electrode reaches a preset threshold potential, the step of controlling the battery pack to discharge to the charging pile with the maximum discharge current for a first preset time period is returned to execute until the terminal voltage of the reference battery cell reaches the charging cut-off voltage.

Optionally, the charging pile is a pulse charging pile.

Optionally, the charging pile has a built-in battery discharge circuit, in which a discharge resistor is configured. One end of the discharge resistor is grounded, and the other end is connected to the charging interface of the charging pile via a control switch. When the battery pack is controlled to discharge to the charging pile at the maximum discharge current for a first preset time, the control switch is closed.

Based on the above technical solution, in the above solution provided by the embodiment of the present invention, during the battery pack charging process, the battery pack is firstly subjected to a reverse discharge operation to the charging pile at the maximum discharge current for a first preset time, and then the battery pack is charged by the charging pile, and the whole process is a bidirectional pulse charging process. The use of this charging method for charging has a significant effect on suppressing the lithium deposition phenomenon of the battery pack, can alleviate the polarization phenomenon during the charging process of the battery pack, improve the charging acceptance and safety of the battery pack, and does not require the addition of additional equipment to heat the battery, thereby reducing the waste of resources.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

FIG1 is a schematic diagram of the structure of a charging system provided by the present invention;

FIG2 is a schematic diagram of a flow chart of a low-temperature pulse charging method for a battery disclosed in an embodiment of the present invention;

FIG3 is a schematic flow chart of a low-temperature pulse charging method for a battery according to another embodiment of the present invention;

4 is a schematic diagram of the change of charging and discharging current during the charging and discharging process of the low-temperature pulse charging method for a battery disclosed in an embodiment of the present invention;

FIG5 is a schematic flow chart of a low-temperature pulse charging method for a battery according to another embodiment of the present invention;

Figure 6 is the battery charge and discharge current waveform at the initial moment;

Figure 7 Charging and discharging current waveforms at the end of charging;

FIG8 is a schematic diagram of the structure of a low-temperature pulse charging device for a battery disclosed in an embodiment of the present invention.

DETAILED DESCRIPTION

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

The purpose of the present invention is to provide a low-temperature pulse charging solution for a battery, so as to ensure that the battery can be charged without lithium deposition. At the same time, the technical solution of the embodiment of the present invention does not need to add additional equipment to heat the battery, thereby reducing energy waste.

The low-temperature battery charging method proposed in the embodiment of the present invention utilizes the polarization phenomenon of the battery to heat the battery pack. The battery is first polarized through a short-term discharge. At this time, it is charged again. Due to the existence of the polarization phenomenon, lithium deposition will not occur during battery charging even at low temperatures.

In the technical solution disclosed in the embodiment of the present invention, this patent proposes a charging system, as shown in Figure 1, the system may include a charging pile A and a control module B, the charging pile A is a charging pile with battery charging and discharging functions, for example, it can be a pulse charging pile or other types of charging piles. Specifically, the control module B is used to execute the technical solutions disclosed in the various embodiments of the following battery low-temperature pulse charging method in the process of controlling the charging pile A to charge the battery pack. During the charging process, it is necessary to discharge the battery pack, and the discharge function is realized by the battery discharge circuit built into the charging pile A. In the technical solution disclosed in one embodiment of the present invention, a discharge resistor is configured in the battery discharge circuit, one end of the discharge resistor is grounded, and the other end is connected to the charging interface of the charging pile through a control switch. When the charging pile is controlled to discharge the battery pack, the control switch is closed, and when the battery pack is charged to the charging pile, the control switch is opened, and the current flows to the ground through the discharge resistor.

In the embodiment of the present invention, the battery pack to be charged may be a lithium-ion power battery, each battery pack may include multiple battery modules, each battery module may include multiple single cells, and the connection relationship between the single cells (such as parallel or series) is determined according to the design requirements. The charging pile A uses pulse current to charge and discharge the battery pack in the power battery. The battery pack has a battery cell with a built-in reference electrode, which is called a reference battery cell. In order to facilitate data measurement (such as potential and temperature measurement), the reference battery cell is placed at the corner of the battery pack. The control module B monitors the potential and temperature of the battery cell in real time and controls the charging pile based on the built-in logic of the control module B. It can be understood that the reference battery cell can also be located at other positions of the battery pack.

In the technical solution disclosed in the embodiment of the present invention, all battery cells of the battery pack for charging have good consistency. The battery pack has a special battery cell with a built-in reference electrode, which can be any one of a lithium metal reference electrode, an alloy reference electrode, a polymer material coated reference electrode, and a battery in-situ lithium-plated reference electrode. The terminal voltage, temperature, and potential of the negative electrode relative to the reference electrode of the reference battery cell can be measured in real time. This reference battery cell can be arranged at a position with the best heat dissipation conditions for the battery pack, such as a corner of the battery pack, but is not limited to this.

Refer to Figure 2, which is a flow chart of a battery low-temperature pulse charging method disclosed in an embodiment of the present invention. The battery low-temperature pulse charging method can be applied to the control module of the battery charging system, and the battery charging system includes a charging pile and the control module, that is, the battery low-temperature pulse charging method is the built-in logic of the control module B.

In the technical solution disclosed in the embodiment of the present invention, as shown in FIG2 , the battery low temperature pulse charging method may include:

Step S101: Determine the maximum discharge current of the battery pack.

In the technical solution disclosed in the embodiment of the present invention, the ambient temperature of the battery pack is collected. When the ambient temperature is detected to be lower than the low temperature threshold, it indicates that the battery pack is in a low temperature environment. If it is directly charged, lithium deposition is likely to occur. Therefore, in the embodiment of the present invention, when the battery pack is detected to be in a low temperature environment, the battery pack is discharged with a maximum discharge current of a first preset time (generally less than 1ms), and the temperature of the battery pack is increased by discharging the battery pack. When judging whether the battery pack is in a low temperature environment, the detected ambient temperature of the battery pack can be compared with a preset threshold temperature, and whether the battery pack is in a low temperature environment can be judged based on the comparison result. When the detected ambient temperature is lower than the threshold temperature, it indicates that the battery pack is in a low temperature environment, otherwise it indicates that the battery pack is not in a low temperature environment. When the battery pack is in a low temperature environment, the control logic corresponding to the solution disclosed in the present invention is triggered to realize charging of the battery pack at low temperature. The specific value of the threshold temperature can be set based on the design requirements and battery performance. For example, the temperature threshold can be set to any temperature such as 0°C, -1°C, -2°C, etc. It is understandable that in actual applications, it is also possible not to identify the low temperature environment and directly use the battery low temperature pulse charging method of the embodiment of the present invention. However, it is not meaningful to use the battery low temperature pulse charging method of the embodiment of the present invention when the battery is not at a low temperature. Therefore, it is preferred to execute the battery low temperature pulse charging method of the embodiment of the present invention when the ambient temperature is detected to be lower than the low temperature threshold.

In the technical solution disclosed in the embodiment of the present invention, in order to charge the battery by utilizing the battery polarization phenomenon, in the embodiment of the present invention, during the discharge process, the magnitude of the discharge current needs to be adjusted so that the terminal voltage of the reference battery cell is close to the preset threshold voltage, thereby causing the battery pack to polarize rapidly. Specifically, referring to FIG. 3 , determining the maximum discharge current of the battery pack may specifically include:

Step S201: discharging the battery pack for a second preset time period with the initial discharge current _I1 as the discharge current.

In an embodiment of the present invention, the value of the initial discharge current _I1 can be set according to user experience. Generally, a smaller initial discharge current is set, and the terminal voltage of the corresponding reference battery cell is less than the preset threshold voltage. When setting according to user experience, the principle of no over-discharge is taken as the benchmark, and the present invention does not specifically limit its size. It should be noted that in actual applications, the first preset time length and the second preset time length may be equal or unequal. In order to reduce the control variables during the implementation of the scheme, the first preset time length and the second preset time length may be selected to be equal. However, the size of the first preset time length and the second preset time length should be able to alleviate the battery polarization phenomenon, such as taking tens to hundreds of microseconds.

Step S202: Calculate the difference between the terminal voltage of the reference battery cell and the preset threshold voltage.

Each battery pack includes a plurality of battery cells, one of which is a reference battery cell with a built-in reference electrode. When the battery pack is discharged, the terminal voltage of the reference battery cell is collected, and the difference between the terminal voltage of the reference battery cell and a preset threshold voltage is calculated. The preset threshold voltage is a preset threshold voltage set according to the configuration parameters of the battery pack, and the preset threshold voltage can be determined by the type of the battery pack, for example, the preset threshold voltage of the ternary battery is 2.5V, and the preset threshold voltage of the lithium battery is 2V.

Step S203: determining whether the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within an allowable difference range.

For example, assuming that the discharge current is I ₁ (i) (the initial discharge current is recorded as I ₁ (0), the discharge current after adjustment is recorded as I ₁ (1), and so on), the terminal voltage of the reference battery cell after the battery pack is discharged for a second preset time with the discharge current I ₁ (i) is U ₁ (i), and the preset threshold voltage is U _dch . At the initial moment, i=0, and the initial discharge current I ₁ (0) satisfies U ₁ (0)＜U _dch . It is determined whether U _dch -U ₁ (0) is less than or equal to ε; ε determines the allowable difference range. ε can be based on experience, for example, when ε is 10mV, the allowable difference range ε is 0-10mV. After each discharge current discharges the battery pack for the second preset time, it is determined whether the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is less than or equal to 10mV. When the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is less than or equal to 10mV, it indicates that the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range. If the difference between the terminal voltage of the reference battery cell and the preset threshold voltage exceeds the allowable difference range, step S205 will be entered, otherwise, step S204 will be executed.

Step S204: record the maximum discharge current.

When the discharge current is the initial discharge current, taking the initial discharge current as I ₁ (0) as an example, if U _dch -U ₁ (0) is less than or equal to ε, it indicates that the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range, and the initial discharge current is taken as the maximum discharge current.

Step S205: increasing the amplified current.

Continuing with the example of the initial discharge current being recorded as I ₁ (0), if U _dch -U ₁ (0) is greater than ε, it indicates that the difference between the terminal voltage of the reference battery cell and the preset threshold voltage exceeds the allowable difference range, and the discharge current is increased, that is, the discharge current is increased on the basis of the initial discharge current I ₁ (0).

In some embodiments, when the discharge current is increased, the discharge current can be increased based on a preset step size, that is, the discharge current after the increase is greater than the discharge current before the increase by a preset step size. It should be noted that the preset step size should be small enough, at least the difference between the terminal voltage of the reference battery cell after each increase of the discharge current and the terminal voltage of the reference battery cell before the discharge current is increased should be less than or equal to the error threshold ε corresponding to the allowable error range, so as to ensure that after the discharge current is increased a certain number of times, the difference between the terminal voltage of the reference battery cell and the preset threshold voltage can be within the allowable difference range. Taking the initial discharge current as I ₁ (0) as an example, after the discharge current is increased, i=1, and it is found that the discharge current I ₁ (1) also satisfies U ₁ (1)-U _dch greater than ε. At this time, the above judgment is repeated again until U _dch -U ₁ (i) is less than ε, and the discharge current I ₁ (i) is output as the maximum discharge current. In a specific embodiment, the value of the initial discharge current can be 0, and when adjusting the discharge current, the discharge current is adjusted in a manner that the discharge current increases by 0.1C each time.

When adjusting the size of the discharge current, the charging pile can control the size of the discharge current as required. For example, when discharging the battery pack, the battery pack can be grounded through the discharge resistor in the charging pile. The size of the discharge current of the battery pack can be adjusted by adjusting the resistance value of the discharge resistor in the path.

It is understandable that in some other embodiments, the discharge current may be adjusted in other ways, such as increasing the discharge current according to the difference between the terminal voltage of the previous reference battery cell and the preset threshold voltage. For another example, when the discharge current is just beginning to be adjusted, the first step may be used to adjust, and the difference between the terminal voltage of the reference battery cell and the preset threshold voltage may be continuously compared. When the difference between the terminal voltage of the reference battery cell and the preset threshold voltage exceeds the allowable error range but the value of the excess value is less than a certain threshold, the discharge current may be increased by the second step. It is understandable that the second step should be smaller than the first step, and the second step should be small enough to ensure that after the discharge current is increased a certain number of times, the difference between the terminal voltage of the reference battery cell and the preset threshold voltage can be within the allowable difference range.

Step S102: Control the battery pack to discharge to the charging pile at a maximum discharge current for a first preset time.

In this step, after the maximum discharge current is determined, the battery pack is discharged to the charging pile at the maximum discharge current for a first preset time, that is, the battery pack is discharged at the maximum discharge current for a first preset time (generally less than 1ms). During the discharge process, the temperature of the battery pack continues to rise. It should be noted that the control object in this step is the charging pile, and the purpose of the control is to discharge the battery pack to the charging pile at the maximum discharge current for a first preset time.

During discharge, the discharge current flows to the charging pile. In an embodiment of the present invention, the charging pile refers to a charging pile with charging and discharging functions, which can both charge and discharge the battery pack. The charging and discharging of the battery pack can be achieved by controlling the voltage value of the charging interface of the charging pile. For example, when the battery pack needs to be discharged, the voltage output by the charging pile interface can be controlled to be a low voltage. For example, the charging pile interface is connected to the ground through a discharge resistor. At this time, the charging pile interface voltage is lower than the battery pack charging interface voltage, and the battery pack will discharge to the charging pile. When the charging pile is used to charge the battery pack, the charging pile interface voltage is controlled to switch to a high voltage. At this time, the charging pile will charge the battery pack.

Step S103: After the discharge is completed, the charging pile is controlled to charge the battery pack.

In this step, after the discharge action in step S102 is completed, the charging pile is controlled to charge the battery pack. During the charging process, the battery pack can be charged with the battery standard charging current as the charging current. It is understandable that in some embodiments, the battery pack can be charged with a smaller charging current first, and then the battery pack can be charged with the battery standard charging current as the charging current after a period of time. In addition, the control object in this step is still the charging pile, and the purpose of the control is to charge the battery pack with the charging pile.

In the embodiment of the present invention, for the convenience of description, the duration of the charging process can be recorded as the pulse charging duration _t2 . In the above scheme disclosed in the embodiment of the present invention, as the battery charging process continues to advance, the temperature of the battery pack will continue to rise, the pulse charging duration _t2 will continue to increase, and the amount of electricity charged into the battery pack in each pulse charging cycle will increase, and the charging speed will increase. As shown in Figure 4, as the charging progresses, the pulse charging time _t2 becomes longer to _t2x .

Step S104: During the charging process, the negative electrode potential of the reference battery cell and the potential of the reference electrode are detected.

The reference electrode may refer to the reference electrode of the reference battery cell mentioned above.

Step S105: determining whether the potential of the negative electrode of the reference battery cell relative to the reference electrode reaches a preset threshold potential.

In this step, the potential difference between the negative electrode of the reference battery cell and the reference electrode is calculated to determine whether the potential difference between the two reaches a preset threshold potential. If the preset threshold potential is reached, it indicates that the current charging is completed, and step S106 is executed. If the preset threshold potential is not reached, charging is continued, wherein the preset threshold potential is the lithium deposition potential of the battery pack. In an embodiment of the present invention, the reference electrode of the battery pack may be one of a lithium metal reference electrode, an alloy reference electrode, a polymer material coated reference electrode, and a battery in-situ lithium-plated reference electrode. The lithium deposition potential corresponding to metallic lithium is 0V. Therefore, in order to prevent lithium deposition from occurring at the reference electrode, the preset threshold potential is set to 0V.

Step S106: Return to step S102 and execute until the terminal voltage of the reference battery cell reaches the charging cut-off voltage.

In an embodiment of the present invention, a charge cutoff voltage may be pre-set. The charge cutoff voltage may refer to the terminal voltage of the reference battery cell when the battery pack is in a fully charged state. When the terminal voltage of the reference battery cell reaches the charge cutoff voltage, it indicates that the battery pack is fully charged and the charge and discharge operations on the battery pack are stopped. It should be noted that in some embodiments, each time the potential of the negative electrode of the reference battery cell relative to the reference electrode reaches a preset threshold potential, a judgment may be made as to whether the terminal voltage of the reference battery cell has reached the charge cutoff voltage. When the terminal voltage of the reference battery cell does not reach the charge cutoff voltage, the process returns to step S102. In other embodiments, since the terminal voltage of the reference battery cell will not reach the charge cutoff voltage at the beginning of charging, it may be possible to judge whether the terminal voltage of the reference battery cell has reached the charge cutoff voltage after a certain period of time. The certain period of time here may be determined comprehensively based on the remaining power of the battery pack, the theoretical charging time, etc.

In the embodiment of the present invention, the entire charging process of the battery pack can be shown in FIG4 , wherein in FIG4 , t ₁ is the discharging stage of the battery, and the stages t ₂ and t _2x are the charging stages of the battery.

In the battery low temperature pulse charging method disclosed in the embodiment of the present invention, during the battery pack charging process, the battery pack is firstly reversely discharged to the charging pile at the maximum discharge current for a first preset time, and then the battery pack is charged by the charging pile. The whole process is a bidirectional pulse charging process. The charging method has a significant effect on suppressing the lithium deposition phenomenon of the battery pack, can alleviate the polarization phenomenon during the charging process of the battery pack, improve the charging acceptance and safety of the battery pack, and does not need to add additional equipment to heat the battery, thus reducing the waste of resources.

In the embodiment of the present invention, as the charging process of the battery pack continues, the temperature of the battery pack will continue to rise. If the temperature of the battery pack rises significantly, if the detected current temperature of the battery pack (i.e., the real-time temperature) is greater than the calibrated temperature of the battery pack when the maximum discharge current of the battery is calibrated in step S204 (i.e., the reference temperature), the maximum discharge current can be updated. As shown in FIG. 4 , the maximum discharge current I _1,t is updated to the maximum discharge current I _1,ty after a period of time.

It should be noted that in actual use, when calibrating the maximum discharge current, the temperature of the battery cell with the lowest temperature in the battery pack can be used as the calibration temperature of the battery pack. During the charging and discharging process, the temperature of the battery cell with the lowest temperature in the battery pack can be used as the real-time temperature of the battery pack. Since the discharge current of the battery cell with the lowest temperature in the battery pack is the smallest, when this is used as the standard, other battery cells will not be over-discharged. When the reference battery cell is set at the edge with the best heat dissipation, the temperature of the reference battery cell in the battery pack is the lowest. At this time, the temperature of the reference battery cell can be used as the temperature of the battery pack to ensure that other battery cells will not be over-discharged. That is, referring to Figure 5, the technical solution disclosed in the above embodiment of the present invention may also include:

Step S301: when the difference between the reference battery cell terminal voltage and the preset threshold voltage is within the allowable difference range, the temperature of the battery pack at this time is used as the reference temperature.

That is, in step S204, the temperature of the battery pack is obtained when the maximum discharge current of the battery pack is calibrated. Referring to the above discussion, the reference temperature of the battery pack is recorded as the temperature of the battery cell with the lowest temperature in the battery pack when the maximum discharge current of the battery pack is calibrated.

Step S302: Obtain the real-time temperature of the battery pack.

The real-time temperature of a battery pack may refer to the real-time temperature of a single battery with the lowest temperature in the battery pack, which may be obtained through a temperature sensing device such as a temperature sensor.

Step S303: Determine whether the difference between the reference temperature and the real-time temperature of the battery pack is greater than a preset temperature threshold. If so, re-execute steps S201-S205 to redetermine the maximum discharge current. If not, keep the maximum discharge current of the battery pack unchanged.

In order to more clearly introduce the entire charging process, the present invention will illustrate the charging process with a specific embodiment below. In this embodiment, a battery pack of ternary positive electrode materials is charged. The battery pack has a special battery cell, and the battery cell has a built-in reference electrode (the reference electrode can be made by in-situ lithium plating of copper wire). The special battery cell is the reference battery cell. The terminal voltage, temperature and potential of the negative electrode relative to the reference electrode of the reference battery cell can be measured in real time.

First, the battery pack is discharged for 0.2ms, and the maximum discharge current of the battery pack is 2.4C (ε is 10mV). At this time, the terminal voltage of the reference battery cell is close to the preset threshold voltage of 2.5V.

Then, pulse charging of the battery pack is started. At this time, the battery pack is charged at 1/3C. When the potential of the negative electrode of the reference battery cell relative to the reference electrode reaches the preset threshold potential of 0V, charging is stopped. The pulse charging time is 2ms, and it is switched to 2.4C pulse discharge. The above process is repeated continuously. The pulse charging time continues to increase as the charging progresses. When the temperature of the battery pack stabilizes, the charging time stabilizes at 6ms.

Finally, when the terminal voltage of the reference battery cell reaches the charging cut-off voltage of 4.2V, the battery pack is fully charged.

During the entire charge and discharge process of the battery pack, the charge and discharge current waveforms of the battery pack at the initial moment are shown in FIG6 , and the charge and discharge current waveforms at the final stage of charging are shown in FIG7 . It can be seen from FIG6 and FIG7 that during the charging process of the battery pack, the charging time gradually increases.

This embodiment discloses a low-temperature pulse charging device for a battery. For the specific working contents of each unit in the device, please refer to the contents of the above method embodiment.

The following is a description of a battery low-temperature pulse charging device provided by an embodiment of the present invention. The battery low-temperature pulse charging device described below and the battery low-temperature pulse charging method described above can be referenced to each other.

Referring to FIG8 , the battery low-temperature pulse charging device disclosed in this embodiment is applied to a control module of a battery charging system. The battery charging system includes a charging pile and the control module. The device includes:

A maximum discharge current determination unit 100, for determining a maximum discharge current of a battery pack, wherein the battery pack includes a plurality of battery cells, one of which is a reference battery cell having a built-in reference electrode;

A discharge control unit 200, configured to control the battery pack to discharge to the charging pile at the maximum discharge current for a first preset time period;

The charging unit 300 is used to control the charging pile to charge the battery pack after the discharge is completed. When the potential of the negative electrode of the reference battery cell relative to the reference electrode reaches a preset threshold potential, the discharge control unit 200 is triggered. When the terminal voltage of the reference battery cell reaches the charging cut-off voltage, the charging of the battery pack is stopped.

Corresponding to the above method, in the above battery low temperature pulse charging device, the maximum discharge current determination unit 100 is specifically used for:

The battery pack is discharged for a second preset time period using the initial discharge current as the discharge current, the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is calculated, and it is determined whether the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within an allowable difference range; if it is beyond the allowable difference range, the discharge current is increased and the process returns to the step of discharging the battery pack for the second preset time period until the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range; the discharge current when the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range is used as the maximum discharge current.

Corresponding to the above method, in the above battery low temperature pulse charging device, the maximum discharge current determination unit 100 is specifically used to:

Increase the discharge current based on a preset step size.

Corresponding to the above method, in the above battery low temperature pulse charging device, when the charging unit 300 charges the battery, it is specifically used for:

Charge the battery with the battery standard charging current.

Corresponding to the above method, the above battery low temperature pulse charging device further includes:

Temperature monitoring unit for:

When the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range, the temperature of the battery pack is used as the reference temperature;

Get the real-time temperature of the battery pack;

Determining whether the difference between the reference temperature and the real-time temperature of the battery pack is greater than a preset temperature threshold;

When the difference between the reference temperature and the real-time temperature of the battery pack is greater than a preset temperature threshold, the maximum discharge current determination unit is triggered to update the maximum discharge current of the battery pack.

For the convenience of description, the above system is described as being divided into various modules according to their functions. Of course, when implementing the present invention, the functions of each module can be implemented in the same or multiple software and/or hardware.

Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A battery low temperature pulse charging method, characterized in that it is applied to a control module of a battery charging system, the battery charging system includes a charging pile and the control module, and the method includes: When it is detected that the battery pack is in a low temperature environment, determining a maximum discharge current of the battery pack, the battery pack comprising a plurality of battery cells, one of which is a reference battery cell having a built-in reference electrode; Controlling the battery pack to discharge to the charging pile at the maximum discharge current for a first preset time period; When the discharge is completed, the charging pile is controlled to charge the battery pack, and when the potential of the negative electrode of the reference battery cell relative to the reference electrode reaches a preset threshold potential, the step of controlling the battery pack to discharge to the charging pile at the maximum discharge current for a first preset time period is returned to be executed until the terminal voltage of the reference battery cell reaches a charging cut-off voltage; Among them, as the battery charging process continues to advance, the pulse charging duration will continue to increase. 2. The battery low-temperature pulse charging method according to claim 1, characterized in that the determining the maximum discharge current of the battery pack comprises: The battery pack is discharged for a second preset time period using the initial discharge current as the discharge current, the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is calculated, and it is determined whether the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within an allowable difference range; if it is beyond the allowable difference range, the discharge current is increased and the process returns to the step of discharging the battery pack for the second preset time period until the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range; the discharge current when the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range is used as the maximum discharge current. 3. The battery low temperature pulse charging method according to claim 2, characterized in that increasing the discharge current comprises: Increase the discharge current based on a preset step size. 4. The battery low-temperature pulse charging method according to claim 1, characterized in that charging the battery pack comprises: The battery pack is charged with a standard battery charging current. 5. The battery low temperature pulse charging method according to claim 2, characterized in that it also includes: When the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within an allowable difference range, taking the temperature of the battery pack as a reference temperature; Obtaining the real-time temperature of the battery pack; Determining whether the difference between the reference temperature and the real-time temperature of the battery pack is greater than a preset temperature threshold; When the difference between the reference temperature and the real-time temperature of the battery pack is greater than a preset temperature threshold, the maximum discharge current of the battery pack is re-determined. 6. A battery low-temperature pulse charging device, characterized in that it is applied to a control module of a battery charging system, the battery charging system includes a charging pile and the control module, and the device includes: a maximum discharge current determination unit, configured to determine a maximum discharge current of a battery pack when it is detected that the battery pack is in a low temperature environment, wherein the battery pack includes a plurality of battery cells, one of which is a reference battery cell having a built-in reference electrode; A discharge control unit, used for controlling the battery pack to discharge to the charging pile at the maximum discharge current for a first preset time period; A charging unit, used to control the charging pile to charge the battery pack after the discharge is completed, trigger the discharge control unit when the potential of the negative electrode of the reference battery cell relative to the reference electrode reaches a preset threshold potential, and stop charging the battery pack when the terminal voltage of the reference battery cell reaches a charging cut-off voltage; Among them, as the battery charging process continues to advance, the pulse charging duration will continue to increase. 7. The battery low-temperature pulse charging device according to claim 6, characterized in that the maximum discharge current determination unit, when determining the maximum discharge current of the battery pack, is specifically used to: The battery pack is discharged for a second preset time period using the initial discharge current as the discharge current, the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is calculated, and it is determined whether the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within an allowable difference range; if it is beyond the allowable difference range, the discharge current is increased and the process returns to the step of discharging the battery pack for the second preset time period until the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range; the discharge current when the difference between the terminal voltage of the reference battery cell and the preset threshold voltage is within the allowable difference range is used as the maximum discharge current. 8. A charging system, characterized by comprising: a charging pile and a control module; The charging pile is a charging pile with battery charging and discharging functions; The control module is specifically used for: When it is detected that the battery pack is in a low temperature environment, determining a maximum discharge current of the battery pack, wherein the battery pack includes a plurality of battery cells, one of which is a reference battery cell having a built-in reference electrode; Controlling the battery pack to discharge to the charging pile at the maximum discharge current for a first preset time period; When the discharge is completed, the charging pile is controlled to charge the battery pack, and when the potential of the negative electrode of the reference battery cell relative to the reference electrode reaches a preset threshold potential, the step of controlling the battery pack to discharge to the charging pile at the maximum discharge current for a first preset time period is returned to be executed until the terminal voltage of the reference battery cell reaches a charging cut-off voltage; Among them, as the battery charging process continues to advance, the pulse charging duration will continue to increase. 9 . The charging system according to claim 8 , wherein the charging pile is a pulse charging pile. 10. The charging system according to claim 8 is characterized in that the charging pile has a built-in battery discharge circuit, a discharge resistor is configured in the battery discharge circuit, one end of the discharge resistor is grounded, and the other end is connected to the charging interface of the charging pile through a control switch, and when the battery pack is controlled to discharge to the charging pile at the maximum discharge current for a first preset time, the control switch is closed.