A charging method for a low-temperature cascade charging device for a new energy vehicle power battery

Abstract

The present invention relates to the technical field of charging devices and charging methods, and proposes a charging method for a low-temperature cascade charging device for a new energy vehicle power battery. The method adopts an interval preheating method, selects multiple non-adjacent heating lithium batteries in a low-temperature state to form precharging, thereby achieving the effect of overall preheating of the lithium battery pack, and finally realizes the overall charging operation of the lithium battery pack, so as to realize the charging of the new energy vehicle power battery in a low-temperature state while ensuring the overall endurance of the lithium battery pack. The method comprises a lithium battery pack, an induction detection system, a charging control system and a battery management system. The lithium battery pack comprises multiple energy storage lithium batteries and multiple heating lithium batteries. The charging control system comprises a terminal controller and a combination switch, which is controlled by the terminal controller. The induction detection system comprises an ambient temperature monitor, multiple battery temperature sensors and multiple power sensors. The ambient temperature monitor can accurately sense the ambient temperature of the lithium battery pack.

Description

Technical Field

[0001] The present invention relates to the technical field of charging methods for charging devices, and in particular to a charging method for a low-temperature cascade charging device for a power battery of a new energy vehicle. Background Art

[0002] As we all know, the charging method of the low-temperature cascade charging device for new energy vehicle power batteries is aimed at solving the problem of power battery charging in low-temperature environments, making full use of cascade batteries and improving resource utilization.

[0003] After searching, the invention patent with Chinese patent publication number CN103117421A discloses a low-temperature battery charging method, which is roughly described as comprising the following steps: S1. When the battery temperature is lower than the temperature threshold, pulse charging is performed on the battery, S2. When the battery temperature reaches the temperature threshold, conventional charging is performed on the battery, and the invention patent with Chinese patent publication number CN116053694A discloses a lithium battery low-temperature environment charging system and method, which is roughly described as comprising a lithium battery pack, comprising a plurality of lithium batteries arranged in an array, a lead-acid battery plate, arranged at the bottom of the lithium battery pack, the lead-acid battery plate is electrically connected to the lithium battery pack, the lead-acid battery plate is in thermal contact with the bottom surface of each lithium battery, a heat exchange system, comprising a plurality of heat exchange plates, a micro pump, a circulation pipe and a heating device arranged between each adjacent lithium battery, the heat exchange plate has an inner cavity and is provided inside The cavity is provided with a corrugated support plate, the crests and troughs of the corrugated support plate abut against the inner cavity wall of the heat exchange plate, the gap between the corrugated support plate and the inner cavity wall of the heat exchange plate contains circulating liquid, the circulating pipe connects each heat exchange plate to the heating device to form a circulating loop, and the micro pump is arranged on the circulating pipe. When in use, it includes the following steps: obtaining the temperature detection information of the lithium battery pack, when the detected temperature of the lithium battery pack is higher than the first threshold temperature, the lead-acid battery supplies low power to the heat exchange system, when the detected temperature of the lithium battery pack is lower than the second threshold temperature, the lead-acid battery intermittently supplies high power to the supercapacitor, and the supercapacitor intermittently discharges the lithium battery, when the detected temperature of the lithium battery pack is between the first temperature threshold and the second temperature threshold, the power of the lead-acid battery is detected, if the power is less than the threshold power, the lithium battery charges the capacitor, and the capacitor intermittently charges the lead-acid battery.

[0004] Although the above-mentioned existing technical solutions can realize the charging of new energy vehicle power batteries under low temperature conditions, in actual operation, several array-arranged lithium batteries are charged together, and low temperature conditions are no exception. Charging lithium batteries under low temperature conditions not only affects the battery life, but also affects the charging speed. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a charging method for a low-temperature cascade charging device for a new energy vehicle power battery, which adopts an interval preheating method and selects multiple non-adjacent heated lithium batteries to form pre-charging under a low temperature state, thereby achieving the effect of preheating the entire lithium battery pack, and finally realizing the overall charging operation of the lithium battery pack, so as to realize the charging of the new energy vehicle power battery under a low temperature state while ensuring the overall endurance of the lithium battery pack.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a low-temperature cascade charging device for a new energy vehicle power battery, comprising a lithium battery pack, and also comprising an induction detection system, a charging control system and a battery management system. The lithium battery pack comprises a plurality of energy storage lithium batteries and a plurality of heating lithium batteries. The charging control system comprises a terminal controller and a combination switch, and the combination switch is controlled by the terminal controller. The induction detection system comprises an ambient temperature monitor, a plurality of battery temperature sensors and a plurality of power sensors. The ambient temperature monitor can accurately sense the ambient temperature of the lithium battery pack. The plurality of battery temperature sensors are respectively used for temperature detection of the plurality of energy storage lithium batteries and the temperature detection of the plurality of heating lithium batteries. The plurality of power sensors are respectively used for power detection of the plurality of energy storage lithium batteries and the power detection of the plurality of heating lithium batteries. The battery management system comprises a central controller and a dynamic memory. The central controller and the dynamic memory have an information exchange function. The terminal controller, the ambient temperature monitor, the plurality of battery temperature sensors and the plurality of power sensors are all electrically connected to the central controller. A control system is written in the dynamic memory. The control system is used for charging control of the plurality of energy storage lithium batteries and the plurality of heating lithium batteries.

[0007] Preferably, the combination switch includes a normal temperature electric control switch, a low temperature electric control switch, a normal temperature positive electrode access line, a normal temperature negative electrode access line, a low temperature positive electrode access line and a low temperature negative electrode access line, the normal temperature electric control switch and the low temperature electric control switch are both electrically connected to the terminal controller, the normal temperature positive electrode access line and the normal temperature negative electrode access line are both electrically connected to the normal temperature electric control switch, the positive electrodes of the plurality of energy storage lithium batteries are all electrically connected to the normal temperature positive electrode access line, the negative electrodes of the plurality of energy storage lithium batteries are all electrically connected to the normal temperature negative electrode access line, the low temperature positive electrode access line and the low temperature negative electrode access line are both electrically connected to the low temperature electric control switch, the positive electrodes of the plurality of heating lithium batteries are all electrically connected to the low temperature positive electrode access line, and the negative electrodes of the plurality of heating lithium batteries are all electrically connected to the low temperature negative electrode access line.

[0008] Preferably, the low-temperature positive electrode access line and the low-temperature negative electrode access line are both electrically connected to an external electric switch, the external electric switch is electrically connected to its own charger, the normal temperature positive electrode access line and the normal temperature negative electrode access line are both electrically connected to the own charger, and the external electric switch is electrically connected to the terminal controller.

[0009] Preferably, two of the multiple heating lithium batteries are located at two side edges of the lithium battery group, and the multiple heating lithium batteries at other positions are alternately arranged relative to the multiple energy storage lithium batteries, and two energy storage lithium batteries are arranged between every two adjacent heating lithium batteries.

[0010] Preferably, the central controller is equipped with a communication module.

[0011] Preferably, the control system realizes real-time retrieval of battery status information and dynamically adjusts the charging strategy according to actual changes to ensure charging safety and efficiency.

[0012] Preferably, the control system adopts a verification algorithm to automatically correct the charging parameters to ensure the charging effect.

[0013] The verification algorithm is provided with a heat balance equation matching the heated lithium battery.

[0014] The heat balance equation is:

[0015] ,in

[0016] To heat the density of lithium batteries,

[0017] To heat the specific heat capacity of lithium batteries,

[0018] For the moment The heating lithium battery temperature is

[0019] To heat the lithium battery during charging.

[0020] Heat scattered to heat the lithium battery.

[0021] Preferably, the function formula for heating the heat generated inside the lithium battery during charging is:

[0022] ,in

[0023] is the charging current that varies with time,

[0024] State of charge and temperature A function of the internal resistance of the heated lithium battery.

[0025] Preferably, the function formula of the heat scattered by the heated lithium battery is:

[0026] ,in

[0027] is the heat dissipation coefficient, is the ambient temperature.

[0028] A charging method for a low-temperature cascade charging device for a new energy vehicle power battery comprises the following steps:

[0029] S1. Before use, first set the low temperature threshold. After the low temperature threshold is set, it will be stored in the dynamic memory for the central controller to call. Multiple battery temperature sensors detect the temperature of multiple energy storage lithium batteries and the temperature of multiple heating lithium batteries in real time, and multiple battery temperature sensors transmit the detected temperature data to the central controller in real time. The central controller senses the temperature of multiple energy storage lithium batteries and the temperature of multiple heating lithium batteries in real time;

[0030] S2. Before charging, the central controller senses the ambient temperature through the ambient temperature monitor and compares it with the temperature detected by the battery temperature sensor to determine whether there is any temperature abnormality in the lithium battery pack. If it is determined to be abnormal, the central controller transmits the alarm information through the communication module;

[0031] S3. During charging, when the central controller detects that the temperature of the lithium battery pack is a suitable charging temperature higher than the low temperature threshold, after the matching charging power supply of the lithium battery pack is turned on, multiple energy storage lithium batteries and multiple heating lithium batteries are connected to charge synchronously. When the central controller detects that the temperature of the lithium battery pack is lower than the low temperature threshold, after the matching charging power supply of the lithium battery pack is turned on, multiple heating lithium batteries are connected to charge synchronously, and multiple energy storage lithium batteries are not connected to charge. Heat is generated along with the charging of the multiple heating lithium batteries, so that the overall temperature of the lithium battery pack is increased. When the overall temperature of the lithium battery pack reaches a suitable charging temperature higher than the low temperature threshold, multiple energy storage lithium batteries are connected to charge.

[0032] S4. During the charging process, when the power sensor corresponding to the heating lithium battery detects that the heating lithium battery is fully charged, the heating lithium battery is controlled to stop charging. When the power sensor corresponding to the energy storage lithium battery detects that the energy storage lithium battery is fully charged, the energy storage lithium battery is controlled to stop charging. The charging of both the energy storage lithium battery and the heating lithium battery is completed to realize the overall charging of the lithium battery pack.

[0033] Compared with the prior art, the present invention provides a charging method for a low-temperature cascade charging device for a new energy vehicle power battery, which has the following beneficial effects:

[0034] (1) In the present invention, two independent charging systems are formed by the cooperation of multiple energy storage lithium batteries and multiple heating lithium batteries, which facilitates the formation of successive charging. By adopting the interval preheating method, multiple non-adjacent heating lithium batteries are selected to form pre-charging under low temperature conditions, thereby achieving the effect of overall preheating of the lithium battery pack, and finally realizing the overall charging operation of the lithium battery pack, realizing the charging of the power battery of the new energy vehicle under low temperature conditions while ensuring the overall endurance of the lithium battery pack, ensuring the overall applicability of the lithium battery pack while improving the purpose of protecting the lithium battery pack.

[0035] (2) In the present invention, through the cooperation of the induction detection system, the charging control system and the battery management system, a plurality of energy storage lithium batteries and a plurality of heating lithium batteries are matched to form a corresponding detection and control system, which facilitates the application of the plurality of energy storage lithium batteries and the plurality of heating lithium batteries to different charging modes. At the same time, the energy storage lithium batteries and the heating lithium batteries are matched to form corresponding management, thereby further improving the protection of the lithium battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of signal control of the present invention;

[0037] Figure 2 It is a three-dimensional structural schematic diagram of the relative distribution and wiring status of multiple energy storage lithium batteries and multiple heating lithium batteries of the present invention;

[0038] Figure 3 A curve diagram of charging current drawn by the present invention in combination with specific experimental data;

[0039] Figure 4 The graph of charging capacitance is drawn according to the present invention in combination with specific experimental data.

[0040] In the figure: 1. Energy storage lithium battery; 2. Heating lithium battery; 3. Normal temperature electric control switch; 4. Low temperature electric control switch; 5. Normal temperature positive electrode access line; 6. Normal temperature negative electrode access line; 7. Low temperature positive electrode access line; 8. Low temperature negative electrode access line; 9. External electric switch; 10. Self-charger. DETAILED DESCRIPTION

[0041] 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.

[0042] Example: See Figure 1-Figure 2 A low-temperature cascade charging device for a power battery of a new energy vehicle comprises a lithium battery pack, and also comprises an induction detection system, a charging control system and a battery management system. The lithium battery pack comprises a plurality of energy storage lithium batteries 1 and a plurality of heating lithium batteries 2. Two of the plurality of heating lithium batteries 2 are respectively located at the two side edges of the lithium battery pack, and the plurality of heating lithium batteries 2 at the remaining positions are respectively arranged alternately with respect to the plurality of energy storage lithium batteries 1. Two energy storage lithium batteries 1 are arranged between each two adjacent heating lithium batteries 2. Through the cooperation of the plurality of energy storage lithium batteries 1 and the plurality of heating lithium batteries 2, two independent charging systems are formed, which facilitates the formation of successive cascade charging. By adopting an interval preheating method, a plurality of non-adjacent heating lithium batteries 2 are selected in a low temperature state to form precharging, thereby achieving the effect of overall preheating of the lithium battery pack, and finally realizing the overall charging operation of the lithium battery pack, realizing the charging of the power battery of the new energy vehicle in a low temperature state while ensuring the overall endurance of the lithium battery pack, ensuring the overall applicability of the lithium battery pack while improving the lithium battery For the purpose of group protection, the charging control system includes a terminal controller and a combination switch, the combination switch is controlled by the terminal controller, the induction detection system includes an ambient temperature monitor, multiple battery temperature sensors and multiple power sensors, the ambient temperature monitor can accurately sense the ambient temperature of the lithium battery pack, the multiple battery temperature sensors are respectively used for temperature detection of multiple energy storage lithium batteries 1 and temperature detection of multiple heating lithium batteries 2, the multiple power sensors are respectively used for power detection of multiple energy storage lithium batteries 1 and power detection of multiple heating lithium batteries 2, the battery management system includes a central controller and a dynamic memory, the central controller and the dynamic memory have information exchange function, the terminal controller, the ambient temperature monitor, the multiple battery temperature sensors and the multiple power sensors are electrically connected to the central controller, the central controller is equipped with a communication module, through the communication module with the outside world to realize the central controller relative to the external information transmission, such as communicating with the electronic control system of the vehicle using the lithium battery pack to realize intelligent charging management.

[0043] It should be further explained that a control system is written into the dynamic memory, and the control system is used for charging control of multiple energy storage lithium batteries 1 and multiple heating lithium batteries 2. The combination switch includes a normal temperature electric control switch 3, a low temperature electric control switch 4, a normal temperature positive electrode access line 5, a normal temperature negative electrode access line 6, a low temperature positive electrode access line 7 and a low temperature negative electrode access line 8. The normal temperature electric control switch 3 and the low temperature electric control switch 4 are both electrically connected to the terminal controller, the normal temperature positive electrode access line 5 and the normal temperature negative electrode access line 6 are both electrically connected to the normal temperature electric control switch 3, the positive electrodes of the multiple energy storage lithium batteries 1 are all electrically connected to the normal temperature positive electrode access line 5, and the negative electrodes of the multiple energy storage lithium batteries 1 are all electrically connected to the normal temperature negative electrode The access line 6 is electrically connected, the low-temperature positive electrode access line 7 and the low-temperature negative electrode access line 8 are both electrically connected to the low-temperature electric control switch 4, the positive electrodes of the multiple heating lithium batteries 2 are all electrically connected to the low-temperature positive electrode access line 7, and the negative electrodes of the multiple heating lithium batteries 2 are all electrically connected to the low-temperature negative electrode access line 8. Through the cooperation of the induction detection system, the charging control system and the battery management system, the multiple energy storage lithium batteries 1 and the multiple heating lithium batteries 2 are matched to form a corresponding detection and control system, which facilitates the application of the multiple energy storage lithium batteries 1 and the multiple heating lithium batteries 2 to different charging modes. At the same time, the energy storage lithium batteries 1 and the heating lithium batteries 2 are matched to form corresponding management, which further improves the protection of the lithium battery pack.

[0044] It should be further explained that the control system realizes the real-time retrieval of battery status information, dynamically adjusts the charging strategy according to actual changes, ensures charging safety and efficiency, and adopts a verification algorithm to automatically correct charging parameters to ensure charging effect. The verification algorithm is provided with a thermal balance equation matching the heated lithium battery 2.

[0045] The heat balance equation is:

[0046] ,in

[0047] To heat the density of lithium battery 2,

[0048] To heat the specific heat capacity of lithium battery 2,

[0049] For the moment When the temperature of the heated lithium battery 2 is

[0050] To heat the lithium battery 2 when charging.

[0051] To heat the heat scattered by the lithium battery 2,

[0052] The function formula for heating the heat generated inside the lithium battery 2 during charging is:

[0053] ,in

[0054] is the charging current that varies with time,

[0055] State of charge and temperature A function representing the internal resistance of the heated lithium battery 2,

[0056] Preferably, the function formula of the heat scattered by the heating lithium battery 2 is:

[0057] ,in

[0058] is the heat dissipation coefficient, which is obtained through multiple experiments based on the specific conditions of heating the lithium battery 2. is the ambient temperature, which is detected by the ambient temperature monitor.

[0059] It is also necessary to further explain that the low-temperature positive electrode access line 7 and the low-temperature negative electrode access line 8 are both electrically connected to an external electric switch 9, and the external electric switch 9 is electrically connected to its own charger 10. The normal temperature positive electrode access line 5 and the normal temperature negative electrode access line 6 are both electrically connected to their own charger 10, and the external electric switch 9 is electrically connected to the terminal controller. When the energy storage lithium battery 1 is being charged, due to special reasons, the energy storage lithium battery 1 is not fully charged and the charging is disconnected. The terminal controller will realize the synchronous disconnection of the normal temperature electric control switch 3 and the low temperature electric control switch 4, and control the external electric switch 9 to form a path, so that the self-charger 10 can be connected between the heating lithium battery 2 and the energy storage lithium battery 1, and then the heating lithium battery 2 is used to recharge the energy storage lithium battery 1 until the energy storage lithium battery 1 is fully charged or the power consumption of the heating lithium battery 2 is reduced to the minimum power.

[0060] The simulation experiment of low-temperature cascade charging of new energy vehicle power batteries is as follows:

[0061] The experiment was conducted at different ambient temperatures and different SOC points (State of Charge, which refers to the battery's state of charge, indicating the percentage of the battery's remaining capacity to the total battery capacity) of the lithium battery, including CCCV (Constant Current Constant Voltage) charge and discharge tests and DC+AC (Direct Current and Alternating Current) charging tests. Figure 1The assembled battery pack of the heating lithium battery 2 and the energy storage lithium battery 1 shown in the figure has multiple battery temperature sensors installed on the surface of the heating lithium battery 2 and the energy storage lithium battery 1 with insulating tape. The multiple battery temperature sensors respectively detect the temperature of the multiple heating lithium batteries 2 and the temperature of the multiple energy storage lithium batteries 1 in real time. The battery pack is charged to the specified SOC point using the CCCV charging method, and then the temperature is adjusted to the specified value through the temperature box. After standing for two hours, the battery pack in the temperature box reaches the temperature required for the experiment. Subsequently, the battery pack is charged using the DC+AC charging strategy and the CCCV charging strategy until the battery pack voltage reaches 4.2V, and the temperature, voltage and current are recorded during the experiment. In this experiment, the initial SOC of the DC+AC charging strategy and the CCCV charging strategy are 0%, 20% and 50% respectively, the charging current is set to 2.2A, and the test is conducted at -10℃.

[0062] The specific operation of the experiment includes the following steps:

[0063] (1) Before conducting the experiment, correctly connect the positive and negative poles of the battery pack and the power cord, install the voltage sensor, and finally place the battery pack required for the experiment in the temperature chamber.

[0064] (2) The temperature of the external environment of the battery pack is set to -10°C through a temperature box. The battery pack is discharged at a constant current of 2.2A with a cut-off voltage of 2.5V. After the discharge is completed, the battery pack is left to stand in the temperature box for 1 hour.

[0065] (3) The temperature of the heating lithium battery 2 and the energy storage lithium battery 1 is detected in real time using a battery temperature sensor until the set temperature of the temperature box and the temperatures of the heating lithium battery 2 and the energy storage lithium battery 1 detected by the battery temperature sensor tend to be stable.

[0066] (4) At a current of 2.2A, the heating lithium battery 2 in the battery pack used in the experiment is charged with a constant current, and the temperature of the heating lithium battery 2 and the energy storage lithium battery 1 is monitored at all times. After the temperature of the energy storage lithium battery 1 rises to 0°C, the energy storage lithium battery 1 is charged with a constant current until the capacity in the battery pack reaches 20% of the initial SOC. After charging is completed, the battery pack is left to stand in the temperature box for about 10 minutes (this step is omitted for 0% SOC).

[0067] (5) At a current of 2.2 A, a portion of the battery pack charged to a specified initial SOC in step (4) is charged using a CCCV method, and a portion is charged using a DC+AC method, with a cut-off voltage of 4.2 V. After charging, the battery pack is left to stand for approximately 2 minutes.

[0068] (6) After the rest period, the battery pack used in the experiment was discharged at a constant current of 2.2A to prepare for the next charge of the battery pack. The discharge cut-off voltage was 2.5V. After the discharge was completed, the battery was left to rest for about 2 minutes.

[0069] (7) In order to stabilize the various indicators of the battery pack, the battery pack needs to be left to rest for 1 hour after each charge and discharge cycle.

[0070] (8) Change the initial SOC in step (4) to 50% and 0%, and repeat the charge and discharge experiments at different initial SOCs according to steps (4) to (6).

[0071] After completing the charge and discharge experiment, record the experimental data and select data samples for analysis and research.

[0072] After the battery pack completes the experiment with the initial SOC of 0%, 20%, and 50% at a temperature of -10°C, the temperature needs to be changed to continue the experiment to verify that the DC+AC charging strategy is better than the CCCV charging strategy at different low temperatures. It is worth noting that a new battery pack needs to be replaced before a new experiment to avoid the temperature change affecting the battery pack performance.

[0073] The specific experimental data are as follows (due to the huge amount of experimental data, only part of the data was intercepted):

[0074]

[0075] The charging current curve diagram drawn in combination with specific experimental data is shown in the attached figure. Figure 3 As shown in the figure, the curve diagram of charging capacitance drawn in combination with specific experimental data is shown in the attached figure. Figure 4 shown.

[0076] Experimental conclusion:

[0077] In a low temperature environment, as the temperature decreases, the efficiency of the traditional charging method decreases significantly. For example, at minus 10°C, the traditional charging efficiency may drop to about 60% at room temperature. However, the charging method using the low-temperature ladder charging device for the power battery of a new energy vehicle can still maintain a charging efficiency of more than 80% at room temperature at the same temperature. After repeated experiments, it was found that when the temperature was minus 10°C, the charging efficiency was 80%-85% on average, which shows that the charging method of the low-temperature ladder charging device for the power battery of a new energy vehicle can maintain a high charging efficiency at low temperatures. Ladder charging can effectively extend the service life of the battery pack. By testing the battery pack that has undergone multiple ladder charging experiments, it was found that its capacity decay rate was significantly lower than that of the battery pack using the traditional single charging method. For example, after 500 ladder chargings, the battery pack capacity can still be maintained at about 87% of the initial capacity, while under the traditional charging method, the battery pack capacity may drop to less than 75% of the initial capacity.

[0078] To sum up, the working process of the low-temperature cascade charging device for new energy vehicle power batteries is as follows: before use, first set the low-temperature threshold value, and after the low-temperature threshold value is set, it will be stored in the dynamic memory for the central controller to call, and multiple battery temperature sensors detect the temperature of multiple energy storage lithium batteries 1 and the temperature of multiple heating lithium batteries 2 in real time, and multiple battery temperature sensors transmit the detected temperature data to the central controller in real time. The central controller senses the temperature of multiple energy storage lithium batteries 1 and the temperature of multiple heating lithium batteries 2 in real time. Before charging, the central controller senses the ambient temperature through the ambient temperature monitor and checks it with the temperature detected by the battery temperature sensor to determine whether there is any temperature abnormality in the lithium battery pack. When it is determined that there is an abnormality, the central controller transmits the alarm information through the communication module. During charging, when the central controller detects that the temperature of the lithium battery pack is a suitable charging temperature higher than the low-temperature threshold, it is turned on. After the lithium battery pack is matched with the charging power supply, the normal temperature electric control switch 3 and the low temperature electric control switch 4 both enter the access state, and multiple energy storage lithium batteries 1 and multiple heating lithium batteries 2 are synchronously connected to charge. When the central controller detects that the temperature of the lithium battery pack is lower than the low temperature threshold, after the matching charging power supply of the lithium battery pack is turned on, the low temperature electric control switch 4 enters the access state, and multiple heating lithium batteries 2 are synchronously connected to charge. The normal temperature electric control switch 3 is in an open circuit state, and multiple energy storage lithium batteries 1 are not connected to charging. Heat is generated as the charging of the multiple heating lithium batteries 2 proceeds, so that the overall temperature of the lithium battery pack is increased. When the temperatures of the multiple heating lithium batteries 2 are all higher than the suitable charging temperature of the low temperature threshold, the central controller calls the thermal balance equation to calculate the temperature of the heating lithium battery 2, and compares the calculated value with the corresponding detection value of the corresponding battery temperature sensor. If the two sets of data are within the deviation range, it means that both sets of data are valid.

[0079] Further, according to the specific structure of the lithium battery pack, the corresponding relationship between the temperature change of the heating lithium battery 2 and the temperature change of the energy storage lithium battery 1 is determined by preliminary experiments, as shown in the attached Figure 2 In the arrangement structure of the lithium battery pack shown in the figure, the temperature difference between the heating lithium battery 2 and the energy storage lithium battery 1 is usually maintained between 8 and 10 degrees, that is, after the temperature of the heating lithium battery 2 rises to 8 to 10 degrees above the low temperature threshold, the temperature of the energy storage lithium battery 1 enters above the low temperature threshold, and the calculated relationship is compared with the temperature detected by the battery temperature sensor corresponding to the energy storage lithium battery 1 to achieve verification and confirmation. After that, the normal temperature electric control switch 3 enters the passage state, and multiple energy storage lithium batteries 1 are connected for charging. Under normal circumstances, if the deviation range between the calculated value and the corresponding detection value of the battery temperature sensor is ≤3°C, it is considered that the value is correct. During the charging process, after the power sensor corresponding to the heating lithium battery 2 detects that the heating lithium battery 2 is fully charged, the low temperature electric control switch 4 is controlled to enter the circuit breaker state, and the heating lithium battery 2 stops charging, and the energy storage lithium battery 1 After the corresponding power sensor detects that the energy storage lithium battery 1 is fully charged, the normal temperature electric control switch 3 is controlled to enter the disconnected state, and the energy storage lithium battery 1 stops charging. The energy storage lithium battery 1 and the heating lithium battery 2 are both charged to realize the overall charging of the lithium battery pack. During the charging process of the energy storage lithium battery 1, if the energy storage lithium battery 1 is not fully charged due to special reasons, that is, the charging is disconnected, the terminal controller will realize the synchronous disconnection of the normal temperature electric control switch 3 and the low temperature electric control switch 4, and control the external electric switch 9 to form a path, so that the self-charger 10 can be connected between the heating lithium battery 2 and the energy storage lithium battery 1, and then the heating lithium battery 2 is used to recharge the energy storage lithium battery 1, until the energy storage lithium battery 1 is fully charged or the power consumption of the heating lithium battery 2 is reduced to the minimum power, so as to realize the protection of the energy storage lithium battery 1.

[0080] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A charging method for a low-temperature cascade charging device for a new energy vehicle power battery, characterized in that: The following steps are involved: S1. Before use, a low temperature threshold is first set. After the low temperature threshold is set, it is stored in a dynamic memory for the central controller to call. A plurality of battery temperature sensors detect the temperature of a plurality of energy storage lithium batteries (1) and the temperature of a plurality of heating lithium batteries (2) in real time. The plurality of battery temperature sensors transmit the detected temperature data to the central controller in real time. The central controller senses the temperature of a plurality of energy storage lithium batteries (1) and the temperature of a plurality of heating lithium batteries (2) in real time. S2. Before charging, the central controller senses the ambient temperature through the ambient temperature monitor and compares it with the temperature detected by the battery temperature sensor to determine whether there is any abnormal temperature in the lithium battery pack; S3, during charging, when the central controller detects that the temperature of the lithium battery pack is a suitable charging temperature higher than a low temperature threshold, after the matching charging power supply of the lithium battery pack is turned on, the multiple energy storage lithium batteries (1) and the multiple heating lithium batteries (2) are connected to charge synchronously; when the central controller detects that the temperature of the lithium battery pack is lower than the low temperature threshold, after the matching charging power supply of the lithium battery pack is turned on, the multiple heating lithium batteries (2) are connected to charge synchronously, and the multiple energy storage lithium batteries (1) are not connected to charge. Heat is generated as the multiple heating lithium batteries (2) are charged, so that the overall temperature of the lithium battery pack is increased; when the overall temperature of the lithium battery pack reaches a suitable charging temperature higher than the low temperature threshold, the multiple energy storage lithium batteries (1) are connected to charge; S4, during the charging process, after the power sensor corresponding to the heating lithium battery (2) detects that the heating lithium battery (2) is fully charged, the heating lithium battery (2) is controlled to stop charging, and after the power sensor corresponding to the energy storage lithium battery (1) detects that the energy storage lithium battery (1) is fully charged, the energy storage lithium battery (1) is controlled to stop charging, and the energy storage lithium battery (1) and the heating lithium battery (2) are both fully charged to achieve overall charging of the lithium battery pack; The low-temperature cascade charging device for a new energy vehicle power battery comprises a lithium battery pack, an induction detection system, a charging control system and a battery management system. The lithium battery pack comprises a plurality of energy storage lithium batteries (1) and a plurality of heating lithium batteries (2). Two of the plurality of heating lithium batteries (2) are respectively located at two side edges of the lithium battery pack. The plurality of heating lithium batteries (2) at other positions are respectively arranged alternately with respect to the plurality of energy storage lithium batteries (1). Two energy storage lithium batteries (1) are arranged between each two adjacent heating lithium batteries (2). The charging control system comprises a terminal controller and a combination switch. The combination switch is controlled by the terminal controller. The induction detection system comprises an ambient temperature monitor, a plurality of battery temperature sensors and a plurality of power sensors. The environmental temperature monitor can accurately sense the ambient temperature of the lithium battery pack; the plurality of battery temperature sensors are respectively used for detecting the temperature of the plurality of energy storage lithium batteries (1) and the temperature of the plurality of heating lithium batteries (2); the plurality of power sensors are respectively used for detecting the power of the plurality of energy storage lithium batteries (1) and the power of the plurality of heating lithium batteries (2); the battery management system comprises a central controller and a dynamic memory; the central controller and the dynamic memory have an information exchange function; the terminal controller, the environmental temperature monitor, the plurality of battery temperature sensors and the plurality of power sensors are all electrically connected to the central controller; a control system is written into the dynamic memory; the control system is used for charging control of the plurality of energy storage lithium batteries (1) and the plurality of heating lithium batteries (2); The combined switch comprises a normal temperature electric control switch (3), a low temperature electric control switch (4), a normal temperature positive electrode access line (5), a normal temperature negative electrode access line (6), a low temperature positive electrode access line (7) and a low temperature negative electrode access line (8), the normal temperature electric control switch (3) and the low temperature electric control switch (4) are both electrically connected to the terminal controller, the normal temperature positive electrode access line (5) and the normal temperature negative electrode access line (6) are both electrically connected to the normal temperature electric control switch (3), and a plurality of the energy storage lithium batteries are connected to the terminal controller. The positive electrodes of the battery (1) are all electrically connected to the normal temperature positive electrode access line (5), the negative electrodes of the plurality of energy storage lithium batteries (1) are all electrically connected to the normal temperature negative electrode access line (6), the low temperature positive electrode access line (7) and the low temperature negative electrode access line (8) are all electrically connected to the low temperature electric control switch (4), the positive electrodes of the plurality of heating lithium batteries (2) are all electrically connected to the low temperature positive electrode access line (7), and the negative electrodes of the plurality of heating lithium batteries (2) are all electrically connected to the low temperature negative electrode access line (8); The low-temperature positive electrode access line (7) and the low-temperature negative electrode access line (8) are both electrically connected to an external electric switch (9), and the external electric switch (9) is electrically connected to a self-charger (10). The normal temperature positive electrode access line (5) and the normal temperature negative electrode access line (6) are both electrically connected to the self-charger (10), and the external electric switch (9) is electrically connected to the terminal controller.

2. The charging method of a low-temperature cascade charging device for a new energy vehicle power battery according to claim 1, characterized in that: The central controller is equipped with a communication module.

3. The charging method of a low-temperature cascade charging device for a new energy vehicle power battery according to claim 2, characterized in that: The control system can retrieve battery status information in real time and dynamically adjust the charging strategy according to actual changes to ensure charging safety and efficiency.

4. The charging method of a low-temperature cascade charging device for a new energy vehicle power battery according to claim 3, characterized in that: The control system adopts a verification algorithm to automatically correct the charging parameters to ensure the charging effect. The verification algorithm is provided with a heat balance equation matching the heated lithium battery (2). The heat balance equation is: ,in To heat the density of the lithium battery (2), To heat the specific heat capacity of the lithium battery (2), For the moment The temperature of the heated lithium battery (2) is To heat the lithium battery (2) when charging. The heat is scattered to heat the lithium battery (2).

5. The charging method of a low-temperature cascade charging device for a new energy vehicle power battery according to claim 4, characterized in that: The function formula for heating the internal heat of the lithium battery (2) during charging is: ,in is the charging current that varies with time, R(SOC(t),T(t)) State of charge and temperature A function representing the internal resistance of the heated lithium battery (2).

6. A charging method for a low-temperature cascade charging device for a new energy vehicle power battery according to claim 5, characterized in that: The function formula of the heat scattered by the heated lithium battery (2) is: ,in is the heat dissipation coefficient, is the ambient temperature.

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