A power battery rapid heating and charging method, system, device and electric vehicle

Abstract

The present invention relates to the technical field of power batteries for electric vehicles, and specifically to a method, system, device and electric vehicle for rapid heating and charging of power batteries; the scheme uses the battery temperature, SOC and battery charging MAP at the initial moment to determine the logic of differentiated optimal temperature thresholds, as well as a calculation method for the heating and charging exit threshold, which includes the establishment of an online or offline heating and charging temperature optimization model, and a method for identifying and acquiring simulation key parameters such as PTC characteristics; the scheme can effectively improve the problem of low battery charging rate at low temperatures, and at the same time adopt a current compensation strategy during the heating process. After the battery has the charging capacity, it can enter the heating and charging stage, and its threshold of 5 to 10°C can be reduced to -20°C. Based on the offline calculation or online estimation at the initial moment of charging, the optimal exit temperature of different initial temperatures and SOCs is formulated, thereby shortening the heating time and reducing energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of power batteries for electric vehicles, and in particular to a method, system, device and electric vehicle for rapid heating and charging of a power battery. Background Art

[0002] Existing heating charging usually includes three stages, namely the heating stage, the heating and charging stage, and the charging stage. These three stages are distinguished by preset temperature thresholds. Usually, the termination temperature of the heating stage is -5-0℃, and the termination temperature of the heating and charging stage is 5-10℃. Because the allowable charging current capacity affects the SOC and battery temperature, the optimal heating charging termination temperature usually varies at different SOCs and initial temperatures.

[0003] Under the current method of fixed thresholds for heating and charging, the thresholds set are all compromise thresholds, that is, the thresholds at low temperatures and low SOCs are usually lower than the optimal threshold for charging time, resulting in excessively long charging times; while at high SOCs, the battery takes a shorter time to fully charge, and the heating benefit is not obvious. If the same heating threshold as at low temperatures is adopted, unnecessary energy consumption will be caused.

[0004] Power batteries usually use lithium-ion batteries, and the transmission, embedding and extraction of internal lithium ions are extremely sensitive to temperature. At lower temperatures, mass transfer and chemical reaction activity are low, which greatly limits the allowable charging current limit of the battery, resulting in a decrease in charging speed. In response to the above problems, the current practice in the industry is to heat the battery before heating or charging. The logic of heating charging is the most important factor affecting the low-temperature charging speed of the battery besides the intrinsic charging capacity. Therefore, a reasonable heating charging method can significantly reduce the low-temperature charging time while optimizing energy consumption. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a method, system, device and electric vehicle for rapid heating and charging of power batteries, which can significantly reduce the low-temperature charging time under the premise of optimizing energy consumption.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is: the method for rapid heating and charging of a power battery comprises the following steps:

[0007] (1) Obtain the charging MAP, initial SOC, initial battery temperature, ambient temperature, and PTC characteristic data of the power battery;

[0008] (2) Obtaining corresponding charging time according to multiple heating exit temperatures and charging time calculation models;

[0009] (3) Screening the highest temperature during the charging process to ensure that the highest temperature is lower than the cooling start temperature;

[0010] (4) Tolerance screening of charging time;

[0011] (5) Tolerance screening of energy consumption during charging;

[0012] (6) Obtaining the optimal heating exit temperature result;

[0013] (7) Start the heating and charging process.

[0014] Further, in step (4), the T that does not trigger cooling during the full charging process out Sort the corresponding time t and take the minimum value t min , and its corresponding heating charging exit temperature is recorded as T out1 ;

[0015] Get the heating charging time as t min to min+b The heating charge exit temperature is denoted as T out2 , where b is the upper limit of the time extension allowed to reduce energy consumption, compared with T out1 and T out2 , take the lower value as the heating charging termination temperature T of the current charge out .

[0016] Furthermore, in step (2), the charging time is simulated based on the Bernadi heat generation calculation method for calculating the heat generated by charging according to the battery characteristics, the Newton cooling formula calculation method for calculating the heat dissipation by convection heat transfer, and the Fourier law formula calculation method for calculating the heat dissipation by conduction heat transfer.

[0017] Furthermore, the Bernadi calculation formula is:

[0018]

[0019] In the above formula, Q is the heat generated by the battery; I is the charge and discharge current of the battery, which is positive when charging and negative when discharging; U is the battery voltage; U0 is the open circuit voltage of the battery; T is the battery temperature; is the temperature coefficient; V b is the battery volume.

[0020] Furthermore, the Newtonian cooling formula is:

[0021]

[0022] In the above formula, Δt m is the average temperature difference between the fluid and the solid surface on the heat transfer surface A; A is the convective heat transfer area; h is the convective heat transfer coefficient; Convection heat transfer.

[0023] Furthermore, the Fourier law calculation formula is:

[0024] q = λ·ΔT / L;

[0025] In the above formula, q is the heat flux density per unit area; λ is the thermal conductivity; ΔT is the temperature difference; and L is the thickness.

[0026] The power battery rapid heating and charging system includes a battery status acquisition module, a model calculation module, a tolerance screening module, a strategy output module and a process module;

[0027] The battery status acquisition module acquires the battery's charging MAP, initial SOC, initial battery temperature, ambient temperature, and PTC characteristic data;

[0028] The model calculation module performs simulation calculation on the charging time;

[0029] The tolerance screening module determines whether the current heating exit temperature will cause the temperature of the battery during charging to reach the cooling start temperature.

[0030] Furthermore, the model calculation module includes a Bernadi heat generation calculation unit for calculating charging heat generation according to battery characteristics, a Newton cooling formula calculation unit for calculating convection heat transfer heat dissipation, and a Fourier law formula calculation unit for conducting heat transfer heating calculation.

[0031] The electric vehicle uses the above-mentioned power battery rapid heating and charging system.

[0032] The power battery rapid heating and charging device stores a computer program, and when the computer program is executed by a processor, the power battery rapid heating and charging method described above is implemented.

[0033] Compared with the existing technology, this solution has the following significant advantages:

[0034] This solution can effectively improve the problem of low battery charging rate at low temperatures. At the same time, a current compensation strategy is adopted in the heating process. After the battery has the charging capacity, it can enter the heating charging stage and its 5-10℃ threshold can be reduced to -20℃.

[0035] Secondly, the optimal exit temperature for different initial temperatures and SOCs is determined based on offline calculation or online estimation at the initial moment of charging, thereby shortening the heating time and reducing energy consumption. This solution uses the initial state temperature and SOC for electrothermal coupling optimization calculation, which is highly feasible in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0037] Figure 1 This is a flow chart of the steps of the heating and charging method of the present invention;

[0038] Figure 2 This is a module structure diagram of the heating and charging system of the present invention;

[0039] Figure 3 The present invention is a flowchart of charging time calculation in the heating charging method. DETAILED DESCRIPTION

[0040] The preferred examples of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred examples described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0041] like Figure 1 As shown, the power battery rapid heating charging method of the present invention comprises the following steps:

[0042] (1) Obtain the charging MAP, initial SOC, initial battery temperature, ambient temperature, and PTC characteristic data of the power battery;

[0043] (2) Obtaining corresponding charging time according to multiple heating exit temperatures and charging time calculation models, where: Figure 3 As shown, the charging time is simulated based on the Bernadi heat generation calculation method for charging heat generation calculation according to battery characteristics, the Newton cooling formula calculation method for convective heat transfer heat dissipation calculation, and the Fourier law formula calculation method for conductive heat transfer heating calculation;

[0044] The Bernadi calculation formula is:

[0045]

[0046] In the above formula, Q is the heat generated by the battery; I is the charge and discharge current of the battery, which is positive when charging and negative when discharging; U is the battery voltage; U0 is the open circuit voltage of the battery; T is the battery temperature; is the temperature coefficient; V b is the battery volume;

[0047] The Newtonian cooling formula is:

[0048]

[0049] In the above formula, Δt mis the average temperature difference between the fluid and the solid surface on the heat transfer surface A; A is the convective heat transfer area; h is the convective heat transfer coefficient; It is convection heat transfer;

[0050] The calculation formula of Fourier's law is:

[0051] q = λ·ΔT / L;

[0052] In the above formula, q is the heat flux density per unit area; λ is the thermal conductivity; ΔT is the temperature difference; L is the thickness;

[0053] (3) Screen the maximum temperature during the charging process to ensure that the maximum temperature is lower than the cooling start temperature to avoid energy loss;

[0054] (4) Tolerance screening of charging time, where T is the time when the full charging process does not trigger cooling. out Sort the corresponding time t and take the minimum value t min , and its corresponding heating charging exit temperature is recorded as T out1 ;

[0055] Get the heating charging time as t min to min+b The heating charge exit temperature is denoted as T out2 , where b is the upper limit of the time extension allowed to reduce energy consumption, compared with T out1 and T out2 , take the lower value as the heating charging termination temperature T of the current charge out ;

[0056] (5) Tolerance screening of energy consumption during charging to achieve the same heating and charging effect, the battery heating and charging exit temperature T out The lower it is, the better the energy consumption;

[0057] (6) Obtaining the optimal heating exit temperature result, that is, the optimal temperature with the shortest overall charging time (including heating charging and simple charging after heating exit), the best energy consumption, and no cooling during the full charging process;

[0058] (7) Start the heating and charging process.

[0059] The core of this solution is to use the battery temperature, SOC and battery charging MAP at the initial moment to determine the logic of differentiated optimal temperature thresholds, as well as the calculation method of the heating charging exit threshold. It includes the establishment of an online or offline heating charging temperature optimization model, and the identification and acquisition method of key simulation parameters such as PTC characteristics.

[0060] like Figure 2As shown, the power battery rapid heating and charging system of the present invention includes a battery state acquisition module, a model calculation module, a tolerance screening module, a strategy output module and a process module;

[0061] The battery status acquisition module acquires the battery's charging MAP, initial SOC, initial battery temperature, ambient temperature, and PTC characteristic data;

[0062] The model calculation module performs simulation calculation on the charging time;

[0063] The tolerance screening module determines whether the current heating exit temperature will cause the temperature of the battery during charging to reach the cooling start temperature.

[0064] Among them, the model calculation module includes a Bernadi heat generation calculation unit for calculating charging heat generation according to battery characteristics, a Newton cooling formula calculation unit for calculating convection heat transfer heat dissipation, and a Fourier law formula calculation unit for conducting heat transfer heating.

[0065] The electric vehicle described in the present invention applies the above-mentioned power battery rapid heating and charging system.

[0066] The power battery rapid heating and charging device described in the present invention stores a computer program, and when the computer program is executed by a processor, the above-mentioned power battery rapid heating and charging method is implemented.

[0067] Through the above technical solution, the problem of low battery charging rate at low temperature can be effectively improved. At the same time, a current compensation strategy is adopted in the heating process. After the battery has the charging capacity, it can enter the heating charging stage and its threshold of 5 to 10°C can be reduced to -20°C.

[0068] Secondly, the optimal exit temperature for different initial temperatures and SOCs is determined based on offline calculation or online estimation at the initial moment of charging, thereby shortening the heating time and reducing energy consumption. This solution uses the initial state temperature and SOC for electrothermal coupling optimization calculation, which is highly feasible in engineering.

[0069] Finally, it should be noted that the above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for rapid heating and charging of a power battery, characterized in that: The following steps are involved: (1) Obtain the charging MAP, initial SOC, initial battery temperature, ambient temperature, and PTC characteristic data of the power battery; (2) simulating and calculating the charging time according to multiple heating exit temperatures and a charging time calculation model; (3) Based on the simulation results, the maximum temperature during the charging process is screened to ensure that the maximum temperature is lower than the cooling start-up temperature; (4) Tolerance screening of charging time based on simulation results; (5) Tolerance screening of energy consumption during charging based on simulation results; (6) obtaining an optimal heating exit temperature result based on the screening result; (7) starting the heating and charging process according to the optimal heating exit temperature result; In step (2), based on the Bernadi heat generation calculation formula for calculating the heat generated by charging according to the battery characteristics, the Newton cooling calculation formula for calculating the heat dissipation by convection heat transfer, and the Fourier law calculation formula for calculating the heat dissipation by conduction heat transfer, the charging current is first determined, and then the charging time is determined according to the charging current; The Bernadi heat generation calculation formula is: Among them, Q is the heat generated by the battery; I is the charge and discharge current of the battery, which is positive when charging and negative when discharging; U is the battery voltage; U0 is the open circuit voltage of the battery; T is the battery temperature; is the temperature coefficient; V b is the battery volume; The Newtonian cooling calculation formula is: Among them, Δt m is the average temperature difference between the fluid and the solid surface on the heat transfer surface A; A is the convective heat transfer area; H is the convective heat transfer coefficient; It is convection heat transfer; The Fourier law calculation formula is: q = λ·ΔT / L; Where q is the heat flux per unit area; λ is the thermal conductivity; ΔT is the temperature difference; L is the thickness; In step (4), the T that does not trigger cooling during the full charging process out Sort the corresponding time t and take the minimum value t min , and its corresponding heating charging exit temperature is recorded as T out1 ; Get the heating charging time as t min to min+b The heating charge exit temperature is denoted as T out2 , where b is the upper limit of the time extension allowed to reduce energy consumption, compared with T out1 and T out2 , take the lower value as the heating charging termination temperature T of the current charge out .

2. A power battery rapid heating and charging system, characterized in that: The system includes a battery status acquisition module, a model calculation module, a tolerance screening module, a strategy output module and a process module; The battery status acquisition module is used to acquire the battery's charging MAP, initial SOC, initial battery temperature, ambient temperature, and PTC characteristic data; The model calculation module is used to simulate and calculate the charging time according to multiple heating exit temperatures and charging time calculation models; The tolerance screening module is used to: screen the maximum temperature during the charging process based on the simulation results to ensure that the maximum temperature is lower than the cooling start-up temperature; Based on the simulation results, the charging time is screened for tolerance; Based on the simulation results, the energy consumption during charging is screened for tolerance; The strategy output module is used to obtain the optimal heating exit temperature result based on the screening result; The process module is used to start the heating and charging process according to the optimal heating exit temperature result; The model calculation module is based on the Bernadi heat generation calculation formula for calculating the heat generation of charging according to the battery characteristics, the Newton cooling calculation formula for calculating the heat dissipation by convection heat transfer, and the Fourier law calculation formula for calculating the heat dissipation by conduction heat transfer. The charging current is first determined, and then the charging time is determined according to the charging current. The Bernadi heat generation calculation formula is: Among them, Q is the heat generated by the battery; I is the charge and discharge current of the battery, which is positive when charging and negative when discharging; U is the battery voltage; U0 is the open circuit voltage of the battery; T is the battery temperature; is the temperature coefficient; V b is the battery volume; The Newtonian cooling calculation formula is: Among them, Δt m is the average temperature difference between the fluid and the solid surface on the heat transfer surface A; A is the convective heat transfer area; H is the convective heat transfer coefficient; It is convection heat transfer; The Fourier law calculation formula is: q = λ·ΔT / L; Where q is the heat flux per unit area; λ is the thermal conductivity; ΔT is the temperature difference; L is the thickness; Tolerance screening of charging time includes: T for full charging process without triggering cooling out Sort the corresponding time t and take the minimum value t min , and its corresponding heating charging exit temperature is recorded as T out1 ; Get the heating charging time as t min to min+b The heating charge exit temperature is denoted as T out2 , where b is the upper limit of the time extension allowed to reduce energy consumption, compared with T out1 and T out2 , take the lower value as the heating charging termination temperature T of the current charge out .

3. An electric vehicle, characterized in that: The power battery rapid heating and charging system described in claim 2 above is used.

4. A power battery rapid heating and charging device, characterized in that: The device includes the power battery rapid heating and charging system described in claim 2.

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