Real-time estimation method for equivalent internal resistance of lithium ion battery

Abstract

The invention relates to the technical field of lithium batteries, in particular to a real-time estimation method for equivalent internal resistance of a lithium ion battery, and the method comprises the steps: obtaining first electrical data, second operation data and third physical data of an electric vehicle in real time; obtaining basic equivalent internal resistance according to the first electrical data; obtaining a first operation state compensation coefficient according to the second operation data; obtaining a second deformation compensation coefficient according to the first operation state compensation coefficient and the third physical data, and obtaining a first corrected equivalent internal resistance according to the first operation state compensation coefficient, the second deformation compensation coefficient and the basic equivalent internal resistance; obtaining a third vibration compensation coefficient and a fourth temperature compensation coefficient according to the third physical data, and obtaining a second corrected equivalent internal resistance according to the third vibration compensation coefficient and the first corrected equivalent internal resistance; and obtaining a third corrected equivalent internal resistance according to the fourth temperature compensation coefficient and the second corrected equivalent internal resistance. According to the invention, the accuracy of real-time estimation of the equivalent internal resistance of the lithium ion battery is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of lithium batteries, and in particular to a real-time estimation method for equivalent internal resistance of a lithium-ion battery. Background Art

[0002] Lithium-ion batteries are core power devices widely used in electric vehicles, energy storage systems, consumer electronic devices, drones and other fields. In order to ensure the safety, efficiency and long-term operation of the battery, the lithium-ion battery management system needs to monitor the working status of the battery in real time, including voltage, temperature, state of charge (SoC), discharge rate and other parameters. Among them, equivalent internal resistance (EIR) is a key indicator, which directly affects the power output, heat generation and life attenuation of the battery.

[0003] Equivalent internal resistance refers to the total resistance exhibited by the battery during operation, including ohmic internal resistance, polarization internal resistance and diffusion internal resistance. Real-time acquisition of the internal resistance of the battery can not only reflect its current working status, but also help determine the battery health status (SoH), battery aging, and battery performance under extreme conditions (such as high-speed charging and discharging, extreme temperature). Accurate and real-time internal resistance estimation is crucial to improving the safety and performance of the battery system.

[0004] Real-time estimation of equivalent internal resistance in the electric vehicle field. During the starting, acceleration and braking of electric vehicles, the battery usually works at a high rate, which accelerates the insertion / deinsertion process of lithium ions in the electrode material, which causes the volume of the battery to deform, thereby affecting its internal resistance. In addition, electric vehicles often encounter bumpy roads during driving, which causes acceleration vibrations. These mechanical vibrations interfere with the electrical signals of the battery, causing fluctuations in voltage and current, which in turn affects the estimation accuracy of the internal resistance.

[0005] At present, there are mainly several traditional methods for estimating the internal resistance of lithium-ion batteries for electric vehicles, including DC voltage-current method (DC VI method), AC impedance spectroscopy (EIS) and pulse current method. The above traditional resistance measurement methods mainly rely on electrical signals such as voltage and current, but easily ignore the impact of battery volume deformation and vibration on the equivalent internal resistance, which leads to the problem of low accuracy in equivalent internal resistance estimation.

[0006] Therefore, a real-time estimation method for the equivalent internal resistance of lithium-ion batteries is proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a real-time estimation method of equivalent internal resistance of lithium-ion batteries, by acquiring first electrical data, second operating data and third physical data of electric vehicles in real time; obtaining basic equivalent internal resistance according to the first electrical data; obtaining first operating state compensation coefficient according to the second operating data; and obtaining second deformation compensation coefficient according to the first operating state compensation coefficient and the third physical data, and obtaining first corrected equivalent internal resistance according to the first operating state compensation coefficient, the second deformation compensation coefficient and the basic equivalent internal resistance; obtaining third vibration compensation coefficient and fourth temperature compensation coefficient according to the third physical data, and obtaining second corrected equivalent internal resistance according to the third vibration compensation coefficient and the first corrected equivalent internal resistance; and obtaining third corrected equivalent internal resistance according to the fourth temperature compensation coefficient and the second corrected equivalent internal resistance. The present invention significantly improves the accuracy of real-time estimation of equivalent internal resistance of lithium-ion batteries.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A real-time estimation method for equivalent internal resistance of a lithium-ion battery, comprising:

[0010] S1. Acquire the first electrical data, second operation data and third physical data of the electric vehicle in real time; the first electrical data includes the voltage data U(t) and current data I(t) of the lithium-ion battery of the electric vehicle acquired by the voltage sensor and the current sensor; the second operation data includes the real-time speed, average speed, elapsed time, real-time acceleration and maximum acceleration of the electric vehicle acquired by the on-board sensor; the third physical data includes the volume deformation data, vibration data and temperature data of the lithium-ion battery acquired by the three-dimensional imaging sensor, the three-axis acceleration sensor and the temperature sensor respectively;

[0011] S2. According to the first electrical data, based on Ohm's law, the basic equivalent internal resistance R is obtained. o (t);

[0012] S3. According to the second operation data, obtain a first operation state compensation coefficient; according to the first operation state compensation coefficient and the volume deformation data, obtain a second deformation compensation coefficient, and according to the first operation state compensation coefficient and the second deformation compensation coefficient and the basic equivalent internal resistance R o (t) Get the first corrected equivalent internal resistance R 1 (t);

[0013] S4. According to the vibration data, a third vibration compensation coefficient is obtained, and according to the third vibration compensation coefficient and the first modified equivalent internal resistance R 1 (t) Get the second corrected equivalent internal resistance R 2 (t);

[0014] S5. According to the temperature data, a fourth temperature compensation coefficient is obtained, and according to the fourth temperature compensation coefficient and the second corrected equivalent internal resistance R 2 (t) Get the third corrected equivalent internal resistance R 3 (t).

[0015] Preferably, the basic equivalent internal resistance R o (t) is calculated as:

[0016]

[0017] Among them, R 0 (t) represents the basic equivalent internal resistance; U(t) represents the voltage data; I(t) represents the voltage data.

[0018] Preferably, the operating data includes real-time vehicle speed, average vehicle speed, real-time acceleration, maximum acceleration and driving time; the volume deformation data includes volume change, volume change rate and reference volume; the vibration data includes vibration acceleration and vibration frequency; the temperature data includes real-time operating temperature, maximum operating temperature, minimum operating temperature and reference temperature.

[0019] Preferably, the first operating state compensation coefficient is:

[0020]

[0021] Among them, k motion (t) represents the first running state compensation coefficient; v(t) represents the real-time vehicle speed; v avg (t) represents the average vehicle speed; a(t) represents the real-time acceleration; a max (t) represents the maximum acceleration; t havedr Indicates the elapsed travel time.

[0022] Preferably, the second deformation compensation coefficient is:

[0023]

[0024] Among them, k shape (t) represents the second deformation compensation coefficient, which is used to represent the influence of the volume deformation of the lithium ion battery on the equivalent internal resistance of the lithium ion battery; α v Denotes deformation correction factor; ΔV shape (t) represents the volume change; V 0 represents the reference volume; Expressed as the volume change rate; k motion (t) is represented as the first operating state compensation coefficient.

[0025] Preferably, the first corrected equivalent internal resistance is:

[0026] R 1 (t) = k shape (t)*R 0 (t);

[0027] Among them, R 1 (t) is represented by the first modified equivalent internal resistance; k shape (t) is represented as the second deformation compensation coefficient.

[0028] Preferably, the third vibration compensation coefficient is:

[0029] k vib (t) = α vib *V vib (t)*(1+β f *f vib (t));

[0030] Among them, k vib (t) represents the third vibration compensation coefficient, which is used to represent the influence of the vibration of the lithium-ion battery on the equivalent internal resistance; α vib Represents the vibration acceleration influence factor; V vib (t) represents vibration acceleration; β f Vibration frequency influence factor; f vib (t) represents the vibration frequency;

[0031] Preferably, the calculation formula of the vibration acceleration is:

[0032]

[0033] in, Respectively represent the vibration acceleration components in the x, y, and z dimensions;

[0034] The vibration frequency is obtained by adjusting the vibration acceleration V vib (t) Perform Fourier transform and extract the frequency domain component;

[0035] Preferably, the second corrected equivalent internal resistance is:

[0036] R 2 (t) = k vib (t)*R 1 (t);

[0037] Among them, R 2 (t) is represented by the second modified equivalent internal resistance; k vib (t) is represented by the third vibration compensation coefficient; R 1 (t) is represented as the first corrected equivalent internal resistance.

[0038] Preferably, the fourth temperature compensation coefficient is:

[0039]

[0040] Among them, k tep (t) represents the fourth temperature compensation coefficient, which is used to represent the influence of temperature change on the equivalent internal resistance; δ T represents the temperature influence factor; TEP(t) represents the real-time operating temperature; TEP max Indicates the maximum operating temperature; TEP min Indicates the minimum operating temperature; TEP 0 Indicates the reference temperature.

[0041] Preferably, the third modified equivalent internal resistance is:

[0042] R 3 (t) = k tep (t)*R 2 (t);

[0043] Among them, R 3 (t) is represented by the third modified equivalent internal resistance; k tep (t) is represented by the fourth temperature compensation coefficient; R 2 (t) represents the second corrected equivalent internal resistance.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. The present invention obtains the first electrical data, the second operating data and the third physical data of the electric vehicle in real time, and obtains the basic equivalent internal resistance according to Ohm's law. The first motion compensation coefficient is obtained by considering the second operating data during the driving of the electric vehicle, and the second deformation compensation coefficient is obtained by comprehensively considering the volume deformation data (volume change, volume change rate and basic volume) in the third physical data. The first corrected equivalent internal resistance is obtained according to the second deformation compensation coefficient and the basic equivalent internal resistance. The first corrected equivalent internal resistance comprehensively considers the operating state of the electric vehicle and the volume deformation of the battery, thereby improving the accuracy of the real-time estimation method of the equivalent internal resistance of the lithium-ion battery.

[0046] 2. The present invention obtains a third vibration compensation coefficient by considering the vibration data (vibration acceleration and vibration frequency) of the electric vehicle, and obtains a second corrected equivalent internal resistance based on the third vibration compensation coefficient and the first corrected equivalent internal resistance. The second corrected equivalent internal resistance further considers the influence of the mechanical vibration data of the electric vehicle on the equivalent internal resistance, which lays a good foundation for the final estimation of the battery equivalent internal resistance, thereby facilitating the improvement of the accuracy of the real-time estimation method of the battery equivalent internal resistance.

[0047] 3. The present invention obtains a fourth temperature compensation coefficient by considering the temperature of the electric vehicle (real-time operating temperature, maximum operating temperature, minimum operating temperature and reference temperature), and obtains a third corrected equivalent internal resistance based on the fourth temperature compensation coefficient and the second corrected equivalent internal resistance. The third corrected equivalent internal resistance further considers the influence of the operating temperature of the electric vehicle on the equivalent internal resistance on the basis of considering the motion state and volume deformation of the electric vehicle, which reflects the comprehensiveness of the real-time estimation method of the equivalent internal resistance and further improves the accuracy of the real-time estimation method of the battery equivalent internal resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic flow chart of a method for real-time estimation of equivalent internal resistance of a lithium-ion battery proposed in an embodiment of the present invention;

[0049] Figure 2 A schematic diagram of a third modified equivalent internal resistance calculation process proposed in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] 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.

[0051] Embodiment 1

[0052] A laboratory is currently studying the real-time estimation of the equivalent internal resistance of lithium-ion batteries in electric vehicles. In order to improve the accuracy of the real-time estimation method of the equivalent internal resistance of lithium-ion batteries, a real-time estimation method of the equivalent internal resistance of lithium-ion batteries is applied;

[0053] Reference Figure 1 , which is a flow chart of a real-time estimation method for equivalent internal resistance of a lithium-ion battery, comprising:

[0054] S1. Acquire the first electrical data, second operation data and third physical data of the electric vehicle in real time; the first electrical data includes the voltage data U(t) and current data I(t) of the lithium-ion battery of the electric vehicle acquired by the voltage sensor and the current sensor; the second operation data includes the real-time speed, average speed, elapsed time, real-time acceleration and maximum acceleration of the electric vehicle acquired by the on-board sensor; the third physical data includes the volume deformation data, vibration data and temperature data of the lithium-ion battery acquired by the three-dimensional imaging sensor, the three-axis acceleration sensor and the temperature sensor respectively;

[0055] The three-dimensional imaging sensor is usually installed in the battery compartment of the electric vehicle, the three-axis acceleration sensor is installed on the outer shell of the battery pack; the temperature sensor is installed on the outer shell of the battery pack;

[0056] Before the electric vehicle is driven, the three-dimensional imaging sensor is used to scan each battery in the battery pack to obtain the reference volume of the lithium-ion battery; the total volume of the lithium-ion battery pack is monitored in real time during driving, and the volume change is calculated in real time;

[0057] S2. According to the first electrical data, based on Ohm's law, the basic equivalent internal resistance R is obtained. o (t);

[0058] S3. According to the second operation data, obtain a first operation state compensation coefficient; according to the first operation state compensation coefficient and the volume deformation data, obtain a second deformation compensation coefficient, and according to the first operation state compensation coefficient and the second deformation compensation coefficient and the basic equivalent internal resistance R o (t) Get the first corrected equivalent internal resistance R 1 (t);

[0059] S4. According to the vibration data, a third vibration compensation coefficient is obtained, and according to the third vibration compensation coefficient and the first modified equivalent internal resistance R 1 (t) Get the second corrected equivalent internal resistance R 2 (t);

[0060] S5. According to the temperature data, a fourth temperature compensation coefficient is obtained, and according to the fourth temperature compensation coefficient and the second corrected equivalent internal resistance R 2 (t) Get the third corrected equivalent internal resistance R 3 (t).

[0061] Furthermore, the basic equivalent internal resistance R o (t) is calculated as:

[0062]

[0063] Among them, R 0 (t) represents the basic equivalent internal resistance; U(t) represents the voltage data; I(t) represents the voltage data.

[0064] Furthermore, the operating data includes real-time vehicle speed, average vehicle speed, real-time acceleration, maximum acceleration and driving time; the volume deformation data includes volume change, volume change rate and reference volume; the vibration data includes vibration acceleration and vibration frequency; the temperature data includes real-time operating temperature, maximum operating temperature, minimum operating temperature and reference temperature.

[0065] Before the electric vehicle is driven, the battery shell is scanned with high precision by a 3D imaging sensor to generate a 3D point cloud mesh model of the battery shell. The model records every spatial coordinate point on the surface of the battery pack to form a complete 3D shape. By performing volume integration on the scanned 3D point cloud data, the initial volume of the battery is calculated and recorded as the reference volume. During the driving of the electric vehicle, the 3D imaging sensor monitors the 3D point cloud mesh model of the battery shell in real time, dynamically updates the volume of the battery pack, and compares it with the reference volume to obtain the volume change, and obtains the volume change rate based on the driving time and the real-time volume change;

[0066] Furthermore, the first operating state compensation coefficient is:

[0067]

[0068] Among them, k motion (t) represents the first running state compensation coefficient; v(t) represents the real-time vehicle speed; v avg (t) represents the average vehicle speed; a(t) represents the real-time acceleration; a max (t) represents the maximum acceleration; t havedr Indicates the elapsed travel time.

[0069] Furthermore, the second deformation compensation coefficient is:

[0070]

[0071] Among them, k shape (t) represents the second deformation compensation coefficient, which is used to represent the influence of the volume deformation of the lithium ion battery on the equivalent internal resistance of the lithium ion battery; α v Denotes deformation correction factor; ΔV shape (t) represents the volume change; V 0 represents the reference volume; Expressed as the volume change rate; k motion (t) is represented as the first operating state compensation coefficient.

[0072] Furthermore, the first corrected equivalent internal resistance is:

[0073] R 1 (t) = k shape (t)*R 0 (t);

[0074] Among them, R 1 (t) is represented by the first modified equivalent internal resistance; k shape (t) is represented as the second deformation compensation coefficient.

[0075] This embodiment obtains the first electrical data, the second operating data and the third physical data of the electric vehicle in real time, and obtains the basic equivalent internal resistance according to Ohm's law. The first motion compensation coefficient is obtained by considering the second operating data during the driving of the electric vehicle, and the second deformation compensation coefficient is obtained by comprehensively considering the volume deformation data (volume change, volume change rate and basic volume) in the third physical data. The first corrected equivalent internal resistance is obtained according to the second deformation compensation coefficient and the basic equivalent internal resistance. The first corrected equivalent internal resistance comprehensively considers the operating state of the electric vehicle and the volume deformation of the battery, thereby improving the accuracy of the real-time estimation method of the equivalent internal resistance of the lithium-ion battery.

[0076] Furthermore, the third vibration compensation coefficient is:

[0077] k vib (t) = α vib *V vib (t)*(1+β f *f vib (t));

[0078] Among them, k vib (t) represents the third vibration compensation coefficient, which is used to represent the influence of the vibration of the lithium-ion battery on the equivalent internal resistance; α vib Represents the vibration acceleration influence factor; V vib (t) represents vibration acceleration; β f Vibration frequency influence factor; f vib (t) represents the vibration frequency;

[0079] The triaxial acceleration sensor is used to monitor the acceleration signal components along the three directions of the battery pack: X (horizontal direction of the battery pack), Y (longitudinal direction of the battery pack), and Z (vertical direction of the battery pack). The vibration acceleration V is obtained according to the acceleration signal components in the three directions. vib (t), and by the vibration acceleration V vib (t) performing Fourier transform and extracting the frequency domain component to obtain the vibration frequency;

[0080] Furthermore, the calculation formula of the vibration acceleration is:

[0081]

[0082] Among them, V vibx (t), V viby (t), V vibz (t) represents the vibration acceleration components in the x, y, and z dimensions respectively;

[0083] The vibration frequency is obtained by adjusting the vibration acceleration V vib (t) Perform Fourier transform and extract the frequency domain component;

[0084] Furthermore, the second corrected equivalent internal resistance is:

[0085] R 2 (t) = k vib (t)*R 1 (t);

[0086] Among them, R 2 (t) is represented by the second modified equivalent internal resistance; k vib (t) is represented by the third vibration compensation coefficient; R 1 (t) is represented as the first corrected equivalent internal resistance.

[0087] This embodiment obtains a third vibration compensation coefficient by considering the vibration data (vibration acceleration and vibration frequency) of the electric vehicle, and obtains a second corrected equivalent internal resistance based on the third vibration compensation coefficient and the first corrected equivalent internal resistance. The second corrected equivalent internal resistance further considers the influence of the mechanical vibration data of the electric vehicle on the equivalent internal resistance, which lays a good foundation for the final estimation of the battery equivalent internal resistance, thereby facilitating the improvement of the accuracy of the real-time estimation method of the battery equivalent internal resistance.

[0088] Furthermore, the fourth temperature compensation coefficient is:

[0089]

[0090] Among them, k tep (t) represents the fourth temperature compensation coefficient, which is used to represent the influence of temperature change on the equivalent internal resistance; δ T represents the temperature influence factor; TEP(t) represents the real-time operating temperature; TEP max Indicates the maximum operating temperature; TEP min Indicates the minimum operating temperature; TEP 0 Indicates the reference temperature.

[0091] Furthermore, the third modified equivalent internal resistance is:

[0092] R 3 (t) = k tep (t)*R 2 (t);

[0093] Among them, R 3 (t) is represented by the third modified equivalent internal resistance; k tep (t) is represented by the fourth temperature compensation coefficient; R 2 (t) represents the second corrected equivalent internal resistance.

[0094] Reference Figure 2, which is a schematic diagram of a third corrected equivalent internal resistance calculation process; the progressive relationship of the specific calculation process is basic equivalent internal resistance-first corrected equivalent internal resistance-second corrected equivalent internal resistance-third corrected equivalent internal resistance.

[0095] This embodiment obtains a fourth temperature compensation coefficient by considering the temperature of the electric vehicle (real-time operating temperature, maximum operating temperature, minimum operating temperature and reference temperature), and obtains a third corrected equivalent internal resistance based on the fourth temperature compensation coefficient and the second corrected equivalent internal resistance. The third corrected equivalent internal resistance further considers the influence of the operating temperature of the electric vehicle on the equivalent internal resistance on the basis of considering the motion state and volume deformation of the electric vehicle, which reflects the comprehensiveness of the real-time estimation method of the equivalent internal resistance and further improves the accuracy of the real-time estimation method of the battery equivalent internal resistance.

[0096] This embodiment acquires the first electrical data, the second operating data and the third physical data of the electric vehicle in real time; obtains the basic equivalent internal resistance according to the first electrical data; obtains the first operating state compensation coefficient according to the second operating data; obtains the second deformation compensation coefficient according to the first operating state compensation coefficient and the third physical data, obtains the first corrected equivalent internal resistance according to the first operating state compensation coefficient, the second deformation compensation coefficient and the basic equivalent internal resistance; obtains the third vibration compensation coefficient and the fourth temperature compensation coefficient according to the third physical data, obtains the second corrected equivalent internal resistance according to the third vibration compensation coefficient and the first corrected equivalent internal resistance; and obtains the third corrected equivalent internal resistance according to the fourth temperature compensation coefficient and the second corrected equivalent internal resistance. This embodiment comprehensively considers the motion state and physical changes of the electric vehicle, and significantly improves the accuracy of real-time estimation of the equivalent internal resistance of the lithium-ion battery.

[0097] Embodiment 2

[0098] Laboratory B is engaged in the research of lithium-ion batteries for electric vehicles. Currently, it is studying the real-time estimation of the equivalent internal resistance of lithium-ion batteries for electric vehicles. In order to improve the accuracy of the real-time estimation method of the equivalent internal resistance of lithium-ion batteries, a real-time estimation method of the equivalent internal resistance of lithium-ion batteries is applied;

[0099] Reference Figure 1 , which is a flow chart of a real-time estimation method for equivalent internal resistance of a lithium-ion battery, comprising:

[0100] S1. Acquire the first electrical data, second operation data and third physical data of the electric vehicle in real time; the first electrical data includes the voltage data U(t) and current data I(t) of the lithium-ion battery of the electric vehicle acquired by the voltage sensor and the current sensor; the second operation data includes the real-time speed, average speed, elapsed time, real-time acceleration and maximum acceleration of the electric vehicle acquired by the on-board sensor; the third physical data includes the volume deformation data, vibration data and temperature data of the lithium-ion battery acquired by the three-dimensional imaging sensor, the three-axis acceleration sensor and the temperature sensor respectively;

[0101] The three-dimensional imaging sensor is usually installed in the battery compartment of the electric vehicle, the three-axis acceleration sensor is installed on the outer shell of the battery pack; the temperature sensor is installed on the outer shell of the battery pack;

[0102] Before the electric vehicle is driven, the three-dimensional imaging sensor is used to scan each battery in the battery pack to obtain the reference volume of the lithium-ion battery; the total volume of the lithium-ion battery pack is monitored in real time during driving, and the volume change is calculated in real time;

[0103] S2. According to the first electrical data, based on Ohm's law, the basic equivalent internal resistance R is obtained. o (t);

[0104] S3. According to the second operation data, obtain a first operation state compensation coefficient; according to the first operation state compensation coefficient and the volume deformation data, obtain a second deformation compensation coefficient, and according to the first operation state compensation coefficient and the second deformation compensation coefficient and the basic equivalent internal resistance R o (t) Get the first corrected equivalent internal resistance R 1 (t);

[0105] S4. According to the vibration data, a third vibration compensation coefficient is obtained, and according to the third vibration compensation coefficient and the first modified equivalent internal resistance R 1 (t) Get the second corrected equivalent internal resistance R 2 (t);

[0106] S5. According to the temperature data, a fourth temperature compensation coefficient is obtained, and according to the fourth temperature compensation coefficient and the second corrected equivalent internal resistance R 2 (t) Get the third corrected equivalent internal resistance R 3 (t).

[0107] Furthermore, the basic equivalent internal resistance R o (t) is calculated as:

[0108]

[0109] Among them, R 0 (t) represents the basic equivalent internal resistance; U(t) represents the voltage data; I(t) represents the voltage data.

[0110] Furthermore, the operating data includes real-time vehicle speed, average vehicle speed, real-time acceleration, maximum acceleration and driving time; the volume deformation data includes volume change, volume change rate and reference volume; the vibration data includes vibration acceleration and vibration frequency; the temperature data includes real-time operating temperature, maximum operating temperature, minimum operating temperature and reference temperature.

[0111] Before the electric vehicle is driven, the battery shell is scanned with high precision by a 3D imaging sensor to generate a 3D point cloud mesh model of the battery shell. The model records every spatial coordinate point on the surface of the battery pack to form a complete 3D shape. By performing volume integration on the scanned 3D point cloud data, the initial volume of the battery is calculated and recorded as the reference volume. During the driving process of the electric vehicle, the 3D imaging sensor monitors the 3D point cloud mesh model of the battery shell in real time, dynamically updates the volume of the battery pack, and compares it with the reference volume to obtain the volume change;

[0112] Furthermore, the first operating state compensation coefficient is:

[0113]

[0114] Among them, k motion (t) represents the first running state compensation coefficient; v(t) represents the real-time vehicle speed; v avg (t) represents the average vehicle speed; a(t) represents the real-time acceleration; a max (t) represents the maximum acceleration; t havedr Indicates the elapsed travel time.

[0115] Furthermore, the second deformation compensation coefficient is:

[0116]

[0117] Among them, k shape (t) represents the second deformation compensation coefficient, which is used to represent the influence of the volume deformation of the lithium ion battery on the equivalent internal resistance of the lithium ion battery; α v Denotes deformation correction factor; ΔV shape (t) represents the volume change; V 0 represents the reference volume; Expressed as the volume change rate; k motion (t) is represented as the first operating state compensation coefficient.

[0118] Furthermore, the first corrected equivalent internal resistance is:

[0119] R 1 (t) = k shape (t)*R 0 (t);

[0120] Among them, R 1 (t) is represented by the first modified equivalent internal resistance; k shape (t) is represented as the second deformation compensation coefficient.

[0121] This embodiment obtains the first electrical data, the second operating data and the third physical data of the electric vehicle in real time, and obtains the basic equivalent internal resistance according to Ohm's law. The first motion compensation coefficient is obtained by considering the second operating data during the driving of the electric vehicle, and the second deformation compensation coefficient is obtained by comprehensively considering the volume deformation data (volume change, volume change rate and basic volume) in the third physical data. The first corrected equivalent internal resistance is obtained according to the second deformation compensation coefficient and the basic equivalent internal resistance. The first corrected equivalent internal resistance comprehensively considers the operating state of the electric vehicle and the volume deformation of the battery, thereby improving the accuracy of the real-time estimation method of the equivalent internal resistance of the lithium-ion battery.

[0122] Furthermore, the third vibration compensation coefficient is:

[0123] k vib (t) = α vib *V vib (t)*(1+β f *f vib (t));

[0124] Among them, k vib (t) represents the third vibration compensation coefficient, which is used to represent the influence of the vibration of the lithium-ion battery on the equivalent internal resistance; α vib Represents the vibration acceleration influence factor; V vib (t) represents vibration acceleration; β f Vibration frequency influence factor; f vib (t) represents the vibration frequency;

[0125] The triaxial acceleration sensor is used to monitor the acceleration signal components along the three directions of the battery pack: X (horizontal direction of the battery pack), Y (longitudinal direction of the battery pack), and Z (vertical direction of the battery pack). The vibration acceleration V is obtained according to the acceleration signal components in the three directions. vib (t), and by the vibration acceleration V vib (t) performing Fourier transform and extracting the frequency domain component to obtain the vibration frequency;

[0126] Furthermore, the calculation formula of the vibration acceleration is:

[0127]

[0128] Among them, V vibx (t), V viby (t), V vibz (t) represents the vibration acceleration components in the x, y, and z dimensions respectively;

[0129] The vibration frequency is obtained by adjusting the vibration acceleration V vib (t) Perform Fourier transform and extract the frequency domain component;

[0130] Furthermore, the second corrected equivalent internal resistance is:

[0131] R 2 (t) = k vib (t)*R 1 (t);

[0132] Among them, R 2 (t) is represented by the second modified equivalent internal resistance; k vib (t) is represented by the third vibration compensation coefficient; R 1 (t) is represented as the first corrected equivalent internal resistance.

[0133] This embodiment obtains a third vibration compensation coefficient by considering the vibration data (vibration acceleration and vibration frequency) of the electric vehicle, and obtains a second corrected equivalent internal resistance based on the third vibration compensation coefficient and the first corrected equivalent internal resistance. The second corrected equivalent internal resistance further considers the influence of the mechanical vibration data of the electric vehicle on the equivalent internal resistance, which lays a good foundation for the final estimation of the battery equivalent internal resistance, thereby facilitating the improvement of the accuracy of the real-time estimation method of the battery equivalent internal resistance.

[0134] Furthermore, the fourth temperature compensation coefficient is:

[0135]

[0136] Among them, k tep (t) represents the fourth temperature compensation coefficient, which is used to represent the influence of temperature change on the equivalent internal resistance; δ T represents the temperature influence factor; TEP(t) represents the real-time operating temperature; TEP max Indicates the maximum operating temperature; TEP min Indicates the minimum operating temperature; TEP 0 Indicates the reference temperature.

[0137] Furthermore, the third modified equivalent internal resistance is:

[0138] R 3 (t) = ktep (t)*R 2 (t);

[0139] Among them, R 3 (t) is represented by the third modified equivalent internal resistance; k tep (t) is represented by the fourth temperature compensation coefficient; R 2 (t) represents the second corrected equivalent internal resistance.

[0140] Reference Figure 2 , which is a schematic diagram of a third corrected equivalent internal resistance calculation process; the progressive relationship of the specific calculation process is basic equivalent internal resistance-first corrected equivalent internal resistance-second corrected equivalent internal resistance-third corrected equivalent internal resistance.

[0141] This embodiment obtains a fourth temperature compensation coefficient by considering the temperature of the electric vehicle (real-time operating temperature, maximum operating temperature, minimum operating temperature and reference temperature), and obtains a third corrected equivalent internal resistance based on the fourth temperature compensation coefficient and the second corrected equivalent internal resistance. The third corrected equivalent internal resistance further considers the influence of the operating temperature of the electric vehicle on the equivalent internal resistance on the basis of considering the motion state and volume deformation of the electric vehicle, which reflects the comprehensiveness of the real-time estimation method of the equivalent internal resistance and further improves the accuracy of the real-time estimation method of the battery equivalent internal resistance.

[0142] This embodiment acquires the first electrical data, the second operating data and the third physical data of the electric vehicle in real time; obtains the basic equivalent internal resistance according to the first electrical data; obtains the first operating state compensation coefficient according to the second operating data; obtains the second deformation compensation coefficient according to the first operating state compensation coefficient and the third physical data, obtains the first corrected equivalent internal resistance according to the first operating state compensation coefficient, the second deformation compensation coefficient and the basic equivalent internal resistance; obtains the third vibration compensation coefficient and the fourth temperature compensation coefficient according to the third physical data, obtains the second corrected equivalent internal resistance according to the third vibration compensation coefficient and the first corrected equivalent internal resistance; and obtains the third corrected equivalent internal resistance according to the fourth temperature compensation coefficient and the second corrected equivalent internal resistance. This embodiment comprehensively considers the motion state and physical changes of the electric vehicle, and significantly improves the accuracy of real-time estimation of the equivalent internal resistance of the lithium-ion battery.

[0143] 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 real-time estimation method for equivalent internal resistance of a lithium-ion battery, characterized in that: include: S1. Real-time acquisition of the first electrical data, the second operation data and the third physical data of the electric vehicle; The first electrical data includes voltage data U(t) and current data I(t) of the lithium-ion battery of the electric vehicle acquired by a voltage sensor and a current sensor; The second operation data includes the real-time speed, average speed, elapsed time, real-time acceleration and maximum acceleration of the electric vehicle acquired through the vehicle-mounted sensor; the third physical data includes the volume deformation data, vibration data and temperature data of the lithium-ion battery acquired through the three-dimensional imaging sensor, the three-axis acceleration sensor and the temperature sensor respectively; S2. According to the first electrical data, based on Ohm's law, the basic equivalent internal resistance R is obtained. o (t); S3. According to the second operation data, obtain a first operation state compensation coefficient; according to the first operation state compensation coefficient and the volume deformation data, obtain a second deformation compensation coefficient, and according to the first operation state compensation coefficient and the second deformation compensation coefficient and the basic equivalent internal resistance R o (t) obtaining the first corrected equivalent internal resistance R1(t); S4. Obtaining a third vibration compensation coefficient according to the vibration data, and obtaining a second corrected equivalent internal resistance R2(t) according to the third vibration compensation coefficient and the first corrected equivalent internal resistance R1(t); S5. Obtain a fourth temperature compensation coefficient according to the temperature data, and obtain a third corrected equivalent internal resistance R3(t) according to the fourth temperature compensation coefficient and the second corrected equivalent internal resistance R2(t).

2. A real-time estimation method for equivalent internal resistance of a lithium-ion battery according to claim 1, characterized in that: The basic equivalent internal resistance R o (t) is calculated as: Among them, R0(t) represents the basic equivalent internal resistance; U(t) represents the voltage data; I(t) represents the voltage data.

3. A real-time estimation method for equivalent internal resistance of a lithium-ion battery according to claim 1, characterized in that: The second operating data includes real-time vehicle speed, average vehicle speed, real-time acceleration, maximum acceleration and driving time; the volume deformation data includes volume change, volume change rate and reference volume; the vibration data includes vibration acceleration and vibration frequency; the temperature data includes real-time operating temperature, maximum operating temperature, minimum operating temperature and reference temperature.

4. A real-time estimation method for equivalent internal resistance of a lithium-ion battery according to claim 3, characterized in that: The first operating state compensation coefficient is: Among them, k motion (t) represents the first running state compensation coefficient; v(t) represents the real-time vehicle speed; v avg (t) represents the average vehicle speed; a(t) represents the real-time acceleration; a max (t) represents the maximum acceleration; t havedr Indicates the elapsed travel time.

5. The real-time estimation method of equivalent internal resistance of a lithium-ion battery according to claim 3, characterized in that: The second deformation compensation coefficient is: Among them, k shape (t) represents the second deformation compensation coefficient, which is used to represent the influence of the volume deformation of the lithium ion battery on the equivalent internal resistance of the lithium ion battery; α v Denotes deformation correction factor; ΔV shape (t) represents the volume change; V0 represents the reference volume; Expressed as the volume change rate; k motion (t) is represented as the first operating state compensation coefficient.

6. A real-time estimation method for equivalent internal resistance of a lithium-ion battery according to claim 1, characterized in that: The first corrected equivalent internal resistance is: R1(t)=k shape (t)*R0(t); Wherein, R1(t) represents the first modified equivalent internal resistance; k shape (t) is represented as the second deformation compensation coefficient.

7. A real-time estimation method for equivalent internal resistance of a lithium-ion battery according to claim 1, characterized in that: The third vibration compensation coefficient is: k vib (t)=α vib *V vib (t)*(1+β f *f vib (t)); Among them, k vib (t) represents the third vibration compensation coefficient, which is used to represent the influence of the vibration of the lithium-ion battery on the equivalent internal resistance; α vib Represents the vibration acceleration influence factor; V vib (t) represents vibration acceleration; β f Vibration frequency influence factor; f vib (t) represents the vibration frequency; The calculation formula of the vibration acceleration is: in, Respectively represent the vibration acceleration components in the x, y, and z dimensions; The vibration frequency is obtained by adjusting the vibration acceleration V vib (t) Perform Fourier transform and extract the frequency domain component.

8. The real-time estimation method of equivalent internal resistance of a lithium-ion battery according to claim 1, characterized in that: The second modified equivalent internal resistance is: R2(t)=k vib (t)*R1(t); Wherein, R2(t) represents the second modified equivalent internal resistance; k vib (t) is represented as the third vibration compensation coefficient; R1(t) is represented as the first corrected equivalent internal resistance.

9. A real-time estimation method for equivalent internal resistance of a lithium-ion battery according to claim 1, characterized in that: The fourth temperature compensation coefficient is: Among them, k tep (t) represents the fourth temperature compensation coefficient, which is used to represent the influence of temperature change on the equivalent internal resistance; δ T represents the temperature influence factor; TEP(t) represents the real-time operating temperature; TEP max Indicates the maximum operating temperature; TEP min Indicates the minimum operating temperature; TEP0 indicates the reference temperature.

10. A real-time estimation method for equivalent internal resistance of a lithium-ion battery according to claim 1, characterized in that: The third modified equivalent internal resistance is: R3(t)=k tep (t)*R2(t); Wherein, R3(t) represents the third modified equivalent internal resistance; k tep (t) is represented as the fourth temperature compensation coefficient; R2(t) is represented as the second corrected equivalent internal resistance.

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