Method and device for testing peak power of lithium ion battery

Abstract

The application provides a lithium ion battery peak power test method and device, and relates to the technical field of battery testing. The method comprises the following steps: constructing a Thevenin equivalent circuit model of a lithium ion battery to be tested under a resistance-capacitance link, and determining the maximum pulse current of the lithium ion battery to be tested under different states of charge through the Thevenin equivalent circuit model; calculating the direct current internal resistance of the lithium ion battery to be tested under different states of charge according to the maximum pulse current; determining the target open circuit voltage when the lithium ion battery to be tested reaches the peak current based on the direct current internal resistance, and determining the peak power of the lithium ion battery to be tested according to the peak current and the target open circuit voltage. The application can quickly and accurately evaluate the peak power of the lithium ion battery while avoiding electrochemistry and related hardware devices.

Description

Technical Field

[0001] This invention relates to the field of battery testing technology, and in particular to a method and apparatus for testing the peak power of lithium-ion batteries. Background Technology

[0002] With the increasing severity of energy and environmental issues, new energy vehicles have become a key direction for future development in various countries. Power batteries, represented by lithium-ion batteries, are widely used in electric vehicles due to their advantages of high energy density and low cost. Peak power is one of the important performance indicators of electric vehicles, and its State of Power (SOP) is the limit of power that the battery can input and output under different states, representing the battery's ability to withstand charging and discharging power.

[0003] Peak power is an implicit state of lithium-ion batteries, subject to the combined constraints of operating conditions, temperature, state of charge, and degradation, making it impossible to describe uniformly with a mathematical expression. Extensive experimental verification is necessary, and even then, accuracy is difficult to guarantee. Therefore, evaluating the peak charging and discharging power of power batteries under different temperatures, states of charge, and time periods is crucial for designing powertrains that meet the high-power performance requirements of vehicle acceleration and hill climbing, and for maximizing vehicle regenerative braking capabilities. Furthermore, as a vital indicator throughout the battery's lifespan, the proper use of peak power conditions can prevent overcharging and over-discharging abuse, extending battery life. Measuring and correcting battery peak power using appropriate methods has practical applications.

[0004] In current methods for determining battery peak power, such as Hybrid Pulse Power Characteristic (HPPC) testing, the mainstream approach is to use a single current for charge and discharge testing. However, this method ignores the fact that the maximum current a battery can withstand varies at different states of charge (SOC). According to existing research, DC internal resistance can be categorized into ohmic internal resistance, electrochemical polarization internal resistance, and concentration polarization internal resistance. All three internal resistances of a battery change with increasing discharge rate and current. Furthermore, the temperature rise generated by charging and discharging with different currents also varies, further affecting the battery's DC internal resistance. Therefore, the peak power value obtained by this testing method is not the true peak power. Summary of the Invention

[0005] This invention provides a method for testing the peak power of lithium-ion batteries, which can quickly and accurately evaluate the peak power of lithium-ion batteries without bypassing electrochemistry and related hardware devices.

[0006] This invention provides a method for testing the peak power of a lithium-ion battery, comprising: A Thevenin equivalent circuit model of the lithium-ion battery under test is constructed under the resistance-capacitance circuit, and the maximum pulse current of the lithium-ion battery under test under different states of charge is determined by the Thevenin equivalent circuit model. The DC internal resistance of the lithium-ion battery under test under different states of charge is calculated based on the maximum pulse current. The target open-circuit voltage at which the lithium-ion battery under test reaches its peak current is determined based on the DC internal resistance, and the peak power of the lithium-ion battery under test is determined based on the peak current and the target open-circuit voltage.

[0007] In some embodiments, the model equations of the Thevenin equivalent circuit model are as follows: in, This indicates the open-circuit voltage of the lithium-ion battery under test. This represents the ohmic internal resistance of the lithium-ion battery under test. The polarization voltage is represented by the RC circuit, and I represents the target pulse current to be determined. This indicates the termination voltage of the lithium-ion battery under test.

[0008] In some embodiments, determining the maximum pulse current of the lithium-ion battery under test under different states of charge using the Thevenin equivalent circuit model includes: The constraints for determining the maximum pulse current include: When the lithium-ion battery under test is discharging, the circuit's termination voltage is not less than a preset minimum voltage; when the lithium-ion battery under test is charging, the circuit's termination voltage is not greater than a preset maximum voltage. The target pulse current must be determined to be no more than the specified peak current of the lithium-ion battery under test. Under the RC circuit, the open-circuit voltage, ohmic internal resistance, and polarization voltage under different charging states are obtained; Under the aforementioned constraints, the open-circuit voltage, the ohmic internal resistance, and the polarization voltage are substituted into the Thevenin equivalent circuit model for solution, thereby obtaining the maximum pulse current of the lithium-ion battery under test under different states of charge.

[0009] In some embodiments, the solution process for the Thevenin equivalent circuit model includes: When the applied pulse is an instantaneous pulse, the open-circuit voltage, the ohmic internal resistance, and the termination voltage are substituted into the Thevenin equivalent circuit model for solution, and the target pulse current to be determined is obtained as the maximum pulse current. The polarization voltage is 0. During discharge, the termination voltage is the minimum voltage, and during charging, the termination voltage is the maximum voltage. When the applied pulse is a continuous pulse, the polarization resistance and polarization capacitance under different charging states are obtained, and the differential equation of the polarization voltage is constructed based on the polarization resistance, the polarization capacitance and the target pulse current to be determined. Under the condition that the termination voltage is not less than the minimum voltage, the differential equation is substituted into the Thevenin equivalent circuit model to construct the inequality for the target pulse current to be determined. Solve the inequality to determine the target pulse current and obtain the maximum pulse current.

[0010] In some embodiments, the method further includes: The maximum pulse current is applied to the lithium-ion battery under test for charging or discharging, and the termination voltage during charging or discharging is measured. If the termination voltage is not within the specified voltage range, the maximum pulse current is adjusted until the termination voltage is within the specified voltage range, then charging or discharging is stopped, and the maximum pulse current is corrected using the current pulse current.

[0011] In some embodiments, determining the target open-circuit voltage at which the lithium-ion battery under test reaches its peak current based on the DC internal resistance includes: The lithium-ion battery under test is discharged or charged by the upper limit voltage of the lithium-ion battery under test, and the current open circuit voltage is determined according to the change in state of charge when the peak current is reached. The internal resistance voltage of the lithium-ion battery under test is calculated based on the peak current and the DC internal resistance. The difference between the current open-circuit voltage and the internal resistance voltage divider is determined as the target open-circuit voltage when the lithium-ion battery under test reaches its peak current.

[0012] In some embodiments, determining the current open-circuit voltage based on the change in state of charge when the peak current is reached includes: Determine the discharge capacity of the lithium-ion battery under test: The change in state of charge is calculated based on the discharge or charge time, the peak current, and the discharge capacity, and the current state of charge of the lithium-ion battery under test is determined based on the change value. Obtain the mapping relationship between the state of charge and open-circuit voltage of the lithium-ion battery under test; The current open-circuit voltage is estimated based on the current charge state and the mapping relationship.

[0013] The present invention also provides a testing device for the peak power of a lithium-ion battery, comprising: The model building module is used to construct the Thevenin equivalent circuit model of the lithium-ion battery under test in the context of resistance and capacitance, and to determine the maximum pulse current of the lithium-ion battery under test under different states of charge through the Thevenin equivalent circuit model. An internal resistance calculation module is used to calculate the DC internal resistance of the lithium-ion battery under test under different states of charge based on the maximum pulse current. The power determination module is used to determine the target open-circuit voltage of the lithium-ion battery under test when it reaches the peak current based on the DC internal resistance, and to determine the peak power of the lithium-ion battery under test based on the peak current and the target open-circuit voltage.

[0014] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a method for testing the peak power of a lithium-ion battery as described above.

[0015] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a method for testing the peak power of a lithium-ion battery as described above.

[0016] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements a method for testing the peak power of a lithium-ion battery as described above.

[0017] The method and apparatus for testing the peak power of lithium-ion batteries provided by this invention test the peak power of lithium-ion batteries through pure electrical algorithms without resorting to electrochemical and hardware devices. This results in low testing costs. Furthermore, during the testing process, the maximum current that a lithium-ion battery can withstand varies depending on its DC internal resistance under different states of charge, which is used to calculate the maximum pulse current and DC internal resistance and ultimately evaluate the peak power, ensuring the accuracy and reliability of the peak power test. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced one by one below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the method for testing the peak power of a lithium-ion battery provided by the present invention.

[0020] Figure 2 This is a schematic diagram of the test device for peak power of lithium-ion batteries provided by the present invention.

[0021] Figure 3 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] The method and apparatus for testing the peak power of lithium-ion batteries of the present invention will be described below with reference to the accompanying drawings. Figure 1 This is a flowchart illustrating the method for testing the peak power of a lithium-ion battery provided by the present invention, as shown below. Figure 1 As shown, the method includes the following steps 101 to 103.

[0024] Step 101: Construct the Thevenin equivalent circuit model of the lithium-ion battery under test in the circuit of the resistor-capacitor link, and determine the maximum pulse current of the lithium-ion battery under test under different states of charge through the Thevenin equivalent circuit model.

[0025] The Thevenin equivalent circuit model is specifically designed for analyzing the dynamic characteristics of lithium-ion batteries. By introducing voltage sources, internal resistance, and resistor-capacitor (RC) circuit elements, the model can simulate the electrochemical polarization and concentration polarization phenomena during the charging and discharging process of lithium-ion batteries.

[0026] Here, the Thevenin equivalent circuit model of the lithium-ion battery under test is constructed under the circuit of the resistor-capacitor link. The model equation of the Thevenin equivalent circuit model is as follows: (1) In the above formula (1), This indicates the open-circuit voltage of the lithium-ion battery under test. This represents the ohmic internal resistance of the lithium-ion battery under test. The polarization voltage is represented by the RC circuit, and I represents the target pulse current to be determined. This indicates the termination voltage of the lithium-ion battery under test.

[0027] The embodiments of the present invention, through the construction of the Thevenin equivalent circuit model described above, determine the calculation method for the target pulse current to be determined, providing a model basis for the subsequent calculation of the maximum pulse current using experimental parameters.

[0028] Furthermore, the maximum pulse current of the lithium-ion battery under test under different states of charge (SOC) is determined using the Thevenin equivalent circuit model. Since the open-circuit voltage and ohmic internal resistance of a lithium-ion battery change with SOC, and the polarization resistance and polarization capacitance, used to characterize the dynamic properties of the lithium-ion battery under test, also change with SOC, different SOCs of the lithium-ion battery can be simulated through experiments or parameter identification. The open-circuit voltage, ohmic internal resistance, polarization resistance, and polarization capacitance of the lithium-ion battery under different SOCs can then be measured and obtained, yielding multiple sets of data.

[0029] However, when calculating the maximum pulse current, it is necessary to first determine the limiting conditions for the maximum pulse current. The limiting conditions are different for different specifications of lithium-ion batteries, and the specific implementation should be based on the specifications of the corresponding lithium-ion battery.

[0030] The limitations here include two aspects. The first is the voltage limitation, specifically the circuit's termination voltage during the discharge of the lithium-ion battery under test. Not less than the preset minimum voltage For example, 2.5V / cell is the circuit's termination voltage when the lithium-ion battery under test is charging. No greater than the preset maximum voltage For example, 4.2V / cell.

[0031] Secondly, there is the current limitation, specifically, the target pulse current to be determined must not exceed the peak current specified by the lithium-ion battery under test, denoted as... This peak current is specified by the manufacturer of the lithium-ion battery being tested. Different battery specifications have different peak currents. In practice, the peak current specified by the manufacturer can be used to determine the peak current.

[0032] Optionally, temperature limitations exist in certain scenarios. Specifically, the temperature of the lithium-ion battery under test during pulse heating should theoretically not exceed a certain temperature threshold. In other words, the battery temperature during pulse heating must not be too high, otherwise it may damage the battery and cause an accident. The temperature of the lithium-ion battery under test during pulse heating can generally be calculated after determining the maximum pulse current and DC internal resistance, and is expressed as follows: I is the target pulse current to be determined as the maximum pulse current, and R represents the DC internal resistance.

[0033] Next, in the RC circuit, the open-circuit voltage, ohmic internal resistance, and polarization voltage under different states of charge are obtained. Here, a pulse experiment can be performed on the lithium-ion battery under test. Through experimentation or parameter identification, different states of charge of the lithium-ion battery are simulated, and the open-circuit voltage of the lithium-ion battery is measured and obtained under different states of charge. Ohmic internal resistance Polarization resistance and polarization capacitors Multiple sets of data were obtained. The polarization voltage... It needs to be determined based on the duration t of the pulse applied during the experiment.

[0034] Finally, under the above constraints, the open-circuit voltage, ohmic internal resistance, and polarization voltage are substituted into the Thevenin equivalent circuit model for solution, and the maximum pulse current of the lithium-ion battery under test under different states of charge is obtained.

[0035] Here, multiple sets of data obtained through pulse experiments can be directly substituted into the model equation of the Thevenin equivalent circuit model in the above formula (1). Thus, there is only one unknown in the model equation: the target pulse current I to be determined. Under the two limiting conditions of voltage and current, the corresponding target pulse current to be determined can be obtained. Multiple target pulse currents to be determined can be obtained through multiple sets of data, thereby determining the maximum pulse current.

[0036] In this embodiment of the invention, relevant data obtained from the RC circuit and under different states of charge are substituted into the Thevenin equivalent circuit model to solve for the maximum pulse current. This overcomes the defect in existing technologies that ignore the different maximum currents that the battery can withstand under different states of charge when calculating the battery's peak power. By setting a limit on the maximum pulse current, the reliability of the calculation results is ensured.

[0037] The solution process for Thevenin's equivalent circuit model is explained in detail below.

[0038] First, the pulse experiment is divided into instantaneous pulses and continuous pulses. Under an instantaneous pulse, the pulse time t is less than 1, meaning the pulse time is within one second. In this case, the RC circuit is not considered, and the polarization voltage... Approximately equal to 0, negligible. Continuous pulse refers to a long-term applied pulse; the dynamic polarization of the lithium-ion battery under test must be considered. In this case, the polarization resistance needs to be measured and obtained according to different states of charge. and polarization capacitors To calculate polarization voltage Simultaneously, the open-circuit voltage of lithium-ion batteries under different states of charge was measured and acquired. Ohmic internal resistance Used for calculation and solution.

[0039] When the applied pulse is a transient pulse, the open circuit voltage will be... Ohmic internal resistance and termination voltage Substitute the values ​​into the Thevenin equivalent circuit model for solution, and use the obtained target pulse current I as the maximum pulse current. .in, The polarization voltage is 0, and the termination voltage during discharge is the minimum voltage, i.e. The termination voltage during charging is the maximum voltage mentioned above. Therefore, the model equations of the Thevenin equivalent circuit model can be rewritten as: (2) When the applied pulse is a continuous pulse, the polarization resistance under different charging states is obtained. and polarization capacitor And based on the polarization resistance Polarized capacitors And the target pulse current I to be determined, and the polarization voltage is constructed. The differential equation is expressed as: (3) (4) Furthermore, at the termination voltage Not less than the minimum voltage Under these conditions, substituting the differential equation into the Thevenin equivalent circuit model, we construct the inequality for the target pulse current I to be determined, as follows: (5) Finally, the target pulse current I to be determined in the inequality is solved to obtain the maximum pulse current.

[0040] In the continuous pulse experiment, the open-circuit voltage will be measured and obtained. Ohm resistance Polarization resistance and polarization capacitor Substituting these equations into the system of inequalities formed by formulas (3), (4), and (5) above, the target pulse current I to be determined can be obtained. By measuring and acquiring multiple sets of data under different states of charge, multiple target pulse currents I to be determined can be obtained. In the continuous pulse experiment, the state of charge range is taken as 10% to 90%, with a step size of 10%, thereby determining multiple states of charge and acquiring multiple sets of data.

[0041] In this embodiment of the invention, the dynamic polarization characteristics of lithium-ion batteries during charging or discharging are fully considered in two different pulse scenarios: instantaneous pulse and continuous pulse. This reduces the impact of dynamic polarization characteristics on pulse current and ensures the accuracy of maximum pulse current calculation.

[0042] In some embodiments, after determining the maximum pulse current, it is also necessary to use the maximum pulse current for charging or discharging verification in order to verify and correct the maximum pulse current.

[0043] Specifically, the maximum pulse current is applied to the lithium-ion battery under test to charge or discharge it, and the termination voltage during charging or discharging is measured. At this point, it is determined whether the termination voltage is within the specified voltage range. This specified voltage range is the voltage range that the lithium-ion battery under test is required to achieve. The voltage range is different during charging and discharging, and it is used to determine whether the lithium-ion battery meets the production requirements.

[0044] If the termination voltage is not within the specified voltage range, the maximum pulse current is adjusted until the termination voltage is within the specified voltage range, then charging or discharging is stopped, and the maximum pulse current is corrected using the current pulse current.

[0045] Here, if the termination voltage during charging is not within the preset charging voltage range, the maximum pulse current needs to be adjusted, for example, by increasing or decreasing the maximum pulse current accordingly. Simultaneously, the change in termination voltage is verified until the termination voltage falls within the preset charging voltage range, at which point charging is stopped. The same applies to discharging; if the termination voltage during discharging is not within the preset discharging voltage range, the maximum pulse current also needs to be adjusted, for example, by increasing or decreasing the maximum pulse current accordingly. Simultaneously, the change in termination voltage is verified until the termination voltage falls within the preset discharging voltage range, at which point discharging is stopped.

[0046] When charging or discharging is complete, the current pulse current is the pulse current after it has been increased or decreased. The current pulse current is used to correct the maximum pulse current.

[0047] In this embodiment of the invention, the termination voltage of the lithium-ion battery under test is limited by specifying a voltage range, thereby correcting the maximum pulse current while meeting the requirements of the specified voltage range, further verifying the reliability and accuracy of the maximum pulse current.

[0048] Step 102: Calculate the DC internal resistance of the lithium-ion battery under test under different states of charge based on the maximum pulse current.

[0049] After calculating the maximum pulse current of the lithium-ion battery under test under different states of charge through step 101 above, the DC internal resistance can be further calculated for subsequent calculation of peak power. The formula for calculating the DC internal resistance R is as follows: (6) In the above formula (6), Indicates the maximum pulse current. This represents the termination voltage corresponding to the maximum pulse current. This represents the open-circuit voltage corresponding to the maximum pulse current.

[0050] Step 103: Determine the target open-circuit voltage of the lithium-ion battery under test when it reaches the peak current based on the DC internal resistance, and determine the peak power of the lithium-ion battery under test based on the peak current and the target open-circuit voltage.

[0051] After determining the DC internal resistance in step 102, the voltage divider of the internal resistance can be determined after the lithium-ion battery under test reaches its peak current, thereby determining the open-circuit voltage that the lithium-ion battery under test can output under the peak current operating state, and then the peak power can be calculated.

[0052] In some embodiments, the target open-circuit voltage at which the lithium-ion battery under test reaches its peak current can be determined based on the DC internal resistance, which is explained in detail below.

[0053] First, the lithium-ion battery under test needs to be charged or discharged until it reaches its peak current, denoted as . This peak current characterizes the maximum current that the lithium-ion battery under test can provide under operating conditions.

[0054] Here, the lithium-ion battery under test is discharged or charged using its upper and lower voltage limits. The upper voltage limit of the lithium-ion battery under test is denoted as... This is a fixed value, and the specific value can be provided by the manufacturer of the lithium-ion battery being tested. When the upper limit voltage is exceeded... When the lithium-ion battery under test is charged or discharged, the battery current will fluctuate accordingly, eventually reaching a maximum value, which is called the peak current. .

[0055] Furthermore, the current open-circuit voltage is determined based on the change in state of charge when the peak current is reached. Specifically, the discharge capacity of the lithium-ion battery under test is first determined. The discharge capacity of the lithium-ion battery under test can be obtained through pretreatment. Considering that different battery samples may have different states before being submitted for testing, in order to ensure the consistency of the state and batch of battery test samples, the battery test samples should be in a stable and balanced activated state before testing. Referring to relevant industry standards, the pretreatment process before the formal test is specified as follows: the battery cell / module is charged and discharged five times and adapted to the environment according to a certain process. If the change in discharge capacity between two consecutive tests is not higher than 3% of the rated capacity, the cell / module is considered to have completed the pretreatment, and the pretreatment cycle can be stopped.

[0056] After the above pretreatment process, the lithium-ion battery under test can be determined to have a stable discharge capacity, denoted as . Therefore, based on the discharge or charge time T and the peak current, further analysis can be performed. and discharge capacity The change in the state of charge is calculated and denoted as . The formula is as follows: (6) Next, the current state of charge (SOC) of the lithium-ion battery under test can be determined based on the change value. Since the SOC of the lithium-ion battery under test changes in real time during charging or discharging, it is not easy to measure in real time. However, the current SOC of the lithium-ion battery under test can be directly determined by the change value of the SOC, expressed as SOC + ΔSOC, where SOC represents the original SOC value of the lithium-ion battery under test, generally obtained by designing SOC-OCV tests at different temperatures. Specifically, first, the voltage at the end of the 2-hour resting period after the lithium-ion battery under test is fully charged is recorded, which is expressed as the open-circuit voltage (OCV) at 100% SOC. At room temperature, the SOC is gradually adjusted at 10% or shorter intervals according to the actual discharge capacity until the SOC reaches 0%. After adjusting to each SOC point, the battery is allowed to rest for 2 hours, and the OCV curve at the corresponding SOC state is recorded.

[0057] Here, the mapping relationship between the state of charge and open-circuit voltage of the lithium-ion battery under test is also obtained. The mapping relationship can be obtained by mathematical fitting based on the above OCV curve, and is denoted as f.

[0058] Finally, the current open-circuit voltage can be estimated based on the current charge state and mapping relationship, denoted as . , which represents f(SOC+ΔSOC).

[0059] In this embodiment of the invention, the mapping relationship between the state of charge and open-circuit voltage of the lithium-ion battery under test is determined by designing a SOC-OCV test. After calculating the change in state of charge when charging or discharging reaches the peak current, the open-circuit voltage when the peak current is reached is accurately calculated, which is in line with the theoretical relationship between state of charge and maximum current.

[0060] Furthermore, when the charging or discharging reaches the peak current, the internal resistance voltage of the lithium-ion battery under test is calculated based on the peak current and the DC internal resistance. This can be directly calculated by multiplying the peak current by the DC internal resistance; the internal resistance voltage is denoted as... .

[0061] The difference between the current open-circuit voltage and the voltage divided by the internal resistance is determined as the target open-circuit voltage when the lithium-ion battery under test reaches its peak current. The target open-circuit voltage is denoted as... , represented as: (7) In this embodiment of the invention, based on the peak current reached by discharging or charging the lithium-ion battery under test, the voltage division of the resistor is calculated using the DC internal resistance. Furthermore, under experimental verification, the current open-circuit voltage at the peak current is determined by the change in the state of charge. This allows for the accurate calculation of the target open-circuit voltage at the peak current of the lithium-ion battery under test, characterizing the actual operating voltage of the battery. The entire process avoids electrochemical and hardware devices, requiring only experimental verification and theoretical calculations, making it convenient and quick.

[0062] Finally, based on the peak current and target open circuit voltage Determine the peak power of the lithium-ion battery under test, denoted as . The calculation formula is as follows: (8) This invention, by bypassing electrochemical and hardware devices, tests the peak power of lithium-ion batteries using purely electrical algorithms. This results in low testing costs. Furthermore, during the testing process, the maximum current that a lithium-ion battery can withstand varies depending on its DC internal resistance under different states of charge, which is used to calculate the maximum pulse current and DC internal resistance, and ultimately evaluate the peak power, ensuring the accuracy and reliability of the peak power test.

[0063] The testing apparatus for the peak power of lithium-ion batteries provided by the present invention will be described below. The testing apparatus for the peak power of lithium-ion batteries described below can be referred to in correspondence with the testing method for the peak power of lithium-ion batteries described above.

[0064] like Figure 2As shown, the testing device for the peak power of a lithium-ion battery specifically includes: a model building module 201, an internal resistance calculation module 202, and a power determination module 203. The model building module 201 is used to construct a Thevenin equivalent circuit model of the lithium-ion battery under test in a resistive-capacitive configuration, and to determine the maximum pulse current of the lithium-ion battery under test under different states of charge using the Thevenin equivalent circuit model. The internal resistance calculation module 202 is used to calculate the DC internal resistance of the lithium-ion battery under test under different states of charge based on the maximum pulse current. The power determination module 203 is used to determine the target open-circuit voltage at which the lithium-ion battery under test reaches its peak current based on the DC internal resistance, and to determine the peak power of the lithium-ion battery under test based on the peak current and the target open-circuit voltage.

[0065] In some embodiments, the model building module 201 is further configured to apply the maximum pulse current to the lithium-ion battery under test for charging or discharging, and measure the termination voltage during charging or discharging; if the termination voltage is not within the specified voltage range, the maximum pulse current is adjusted until the termination voltage is within the specified voltage range, then charging or discharging is stopped, and the maximum pulse current is corrected using the current pulse current.

[0066] It should be noted that the beneficial effects of the lithium-ion battery peak power testing device described here correspond to those of the lithium-ion battery peak power testing method mentioned above, therefore the beneficial effects of the lithium-ion battery peak power testing device will not be elaborated here.

[0067] Figure 3 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 3 As shown, the electronic device may include a processor 310, a communications interface 320, a memory 330, and a communication bus 340, wherein the processor 310, communications interface 320, and memory 330 communicate with each other via the communication bus 340. The processor 310 can call logic instructions in the memory 330 to execute a method for testing the peak power of a lithium-ion battery. This method includes: constructing a Thevenin equivalent circuit model of the lithium-ion battery under test in a resistive-capacitive configuration, and determining the maximum pulse current of the lithium-ion battery under test under different states of charge using the Thevenin equivalent circuit model; calculating the DC internal resistance of the lithium-ion battery under test under different states of charge based on the maximum pulse current; determining the target open-circuit voltage at which the lithium-ion battery under test reaches its peak current based on the DC internal resistance; and determining the peak power of the lithium-ion battery under test based on the peak current and the target open-circuit voltage.

[0068] Furthermore, the logical instructions in the aforementioned memory 330 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0069] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the lithium-ion battery peak power test method provided by the above methods. The method includes: constructing a Thevenin equivalent circuit model of the lithium-ion battery under test in a resistive-capacitive circuit, and determining the maximum pulse current of the lithium-ion battery under test under different states of charge through the Thevenin equivalent circuit model; calculating the DC internal resistance of the lithium-ion battery under test under different states of charge based on the maximum pulse current; determining the target open-circuit voltage when the lithium-ion battery under test reaches the peak current based on the DC internal resistance, and determining the peak power of the lithium-ion battery under test based on the peak current and the target open-circuit voltage.

[0070] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements a method for testing the peak power of a lithium-ion battery provided by the methods described above. This method includes: constructing a Thevenin equivalent circuit model of the lithium-ion battery under test in a resistive-capacitive configuration, and determining the maximum pulse current of the lithium-ion battery under test under different states of charge using the Thevenin equivalent circuit model; calculating the DC internal resistance of the lithium-ion battery under test under different states of charge based on the maximum pulse current; determining the target open-circuit voltage at which the lithium-ion battery under test reaches its peak current based on the DC internal resistance; and determining the peak power of the lithium-ion battery under test based on the peak current and the target open-circuit voltage.

[0071] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0072] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing the peak power of a lithium-ion battery, characterized in that, include: A Thevenin equivalent circuit model of the lithium-ion battery under test is constructed under the resistance-capacitance circuit, and the maximum pulse current of the lithium-ion battery under test under different states of charge is determined by the Thevenin equivalent circuit model. The DC internal resistance of the lithium-ion battery under test under different states of charge is calculated based on the maximum pulse current. The target open-circuit voltage at which the lithium-ion battery under test reaches its peak current is determined based on the DC internal resistance, and the peak power of the lithium-ion battery under test is determined based on the peak current and the target open-circuit voltage. The step of determining the maximum pulse current of the lithium-ion battery under test under different states of charge using the Thevenin equivalent circuit model includes: The constraints for determining the maximum pulse current include: When the lithium-ion battery under test is discharging, the circuit's termination voltage is not less than a preset minimum voltage; when the lithium-ion battery under test is charging, the circuit's termination voltage is not greater than a preset maximum voltage. The target pulse current must be determined to be no more than the specified peak current of the lithium-ion battery under test. Under the RC circuit, the open-circuit voltage, ohmic internal resistance, and polarization voltage under different charging states are obtained; Under the aforementioned constraints, the open-circuit voltage, the ohmic internal resistance, and the polarization voltage are substituted into the Thevenin equivalent circuit model for solution, thereby obtaining the maximum pulse current of the lithium-ion battery under test under different states of charge.

2. The method for testing the peak power of a lithium-ion battery according to claim 1, characterized in that, The model equations for the Thevenin equivalent circuit model are as follows: ； in, This indicates the open-circuit voltage of the lithium-ion battery under test. This represents the ohmic internal resistance of the lithium-ion battery under test. The polarization voltage is represented by the RC circuit, and I represents the target pulse current to be determined. This indicates the termination voltage of the lithium-ion battery under test.

3. The method for testing the peak power of a lithium-ion battery according to claim 1, characterized in that, The solution process for the Thevenin equivalent circuit model includes: When the applied pulse is an instantaneous pulse, the open-circuit voltage, the ohmic internal resistance, and the termination voltage are substituted into the Thevenin equivalent circuit model for solution, and the target pulse current to be determined is obtained as the maximum pulse current. The polarization voltage is 0. During discharge, the termination voltage is the minimum voltage, and during charging, the termination voltage is the maximum voltage. When the applied pulse is a continuous pulse, the polarization resistance and polarization capacitance under different charging states are obtained, and the differential equation of the polarization voltage is constructed based on the polarization resistance, the polarization capacitance and the target pulse current to be determined. Under the condition that the termination voltage is not less than the minimum voltage, the differential equation is substituted into the Thevenin equivalent circuit model to construct the inequality for the target pulse current to be determined. Solve the inequality to determine the target pulse current and obtain the maximum pulse current.

4. The method for testing the peak power of a lithium-ion battery according to claim 1, characterized in that, The method further includes: The maximum pulse current is applied to the lithium-ion battery under test for charging or discharging, and the termination voltage during charging or discharging is measured. If the termination voltage is not within the specified voltage range, the maximum pulse current is adjusted until the termination voltage is within the specified voltage range, then charging or discharging is stopped, and the maximum pulse current is corrected using the current pulse current.

5. The method for testing the peak power of a lithium-ion battery according to claim 1, characterized in that, The step of determining the target open-circuit voltage at which the lithium-ion battery under test reaches its peak current based on the DC internal resistance includes: The lithium-ion battery under test is discharged or charged by the upper limit voltage of the lithium-ion battery under test, and the current open circuit voltage is determined according to the change in state of charge when the peak current is reached. The internal resistance voltage of the lithium-ion battery under test is calculated based on the peak current and the DC internal resistance. The difference between the current open-circuit voltage and the internal resistance voltage divider is determined as the target open-circuit voltage when the lithium-ion battery under test reaches its peak current.

6. The method for testing the peak power of a lithium-ion battery according to claim 5, characterized in that, The step of determining the current open-circuit voltage based on the change in state of charge when the peak current is reached includes: Determine the discharge capacity of the lithium-ion battery under test: The change in state of charge is calculated based on the discharge or charge time, the peak current, and the discharge capacity, and the current state of charge of the lithium-ion battery under test is determined based on the change value. Obtain the mapping relationship between the state of charge and open-circuit voltage of the lithium-ion battery under test; The current open-circuit voltage is estimated based on the current charge state and the mapping relationship.

7. A testing device for the peak power of a lithium-ion battery, characterized in that, include: The model building module is used to construct the Thevenin equivalent circuit model of the lithium-ion battery under test in the context of resistance and capacitance, and to determine the maximum pulse current of the lithium-ion battery under test under different states of charge through the Thevenin equivalent circuit model. An internal resistance calculation module is used to calculate the DC internal resistance of the lithium-ion battery under test under different states of charge based on the maximum pulse current. The power determination module is used to determine the target open-circuit voltage of the lithium-ion battery under test when it reaches the peak current based on the DC internal resistance, and to determine the peak power of the lithium-ion battery under test based on the peak current and the target open-circuit voltage. The model building module is specifically used for: The constraints for determining the maximum pulse current include: When the lithium-ion battery under test is discharging, the circuit's termination voltage is not less than a preset minimum voltage; when the lithium-ion battery under test is charging, the circuit's termination voltage is not greater than a preset maximum voltage. The target pulse current must be determined to be no more than the specified peak current of the lithium-ion battery under test. Under the RC circuit, the open-circuit voltage, ohmic internal resistance, and polarization voltage under different charging states are obtained; Under the aforementioned constraints, the open-circuit voltage, the ohmic internal resistance, and the polarization voltage are substituted into the Thevenin equivalent circuit model for solution, thereby obtaining the maximum pulse current of the lithium-ion battery under test under different states of charge.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the method for testing the peak power of a lithium-ion battery as described in any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the method for testing the peak power of a lithium-ion battery as described in any one of claims 1 to 6.

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