Test method, device and equipment for improving estimation accuracy of state of charge of power battery

Abstract

The application discloses a test method and device for improving the estimation accuracy of the state of charge of a power battery and equipment, and relates to the technical field of power batteries. The method comprises the following steps: discharging the power battery to a first state of charge at a constant current and charging the power battery to a second state of charge at a pulse constant current; discharging the power battery, which is at rest, to a third state of charge at a specific temperature; performing a charge-discharge cycle test on the power battery based on the third state of charge and a fourth state of charge; discharging the power battery to the first state of charge; determining the absolute error of the state of charge based on the true value of the state of charge recorded by a charge-discharge device in the charge-discharge test and the state of charge BMS value obtained by a power battery management system, determining the evaluation result of the state of charge, and improving the estimation accuracy of the state of charge of the power battery management system. The absolute error of the state of charge is determined, the evaluation result of the state of charge is determined, the SOC is corrected in real time, and the estimation accuracy of the state of charge of the power battery management system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power batteries, in particular to a test method and device for improving the estimation accuracy of the state of charge of a power battery and equipment. BACKGROUND

[0002] A power battery management system (BMS) ensures the safe and efficient operation of a battery and is crucial for improving the overall performance, safety and cycle life of an electric vehicle. The estimation of the state of charge (SOC) of a battery by the BMS is an important part of power battery management, which can provide accurate battery usage information for the driver or operator, understand the remaining capacity of the battery, and provide basic data for the charge and discharge management, thermal management and health management of the battery. Due to the complex structure of the battery and the numerous factors affecting the state of charge of the battery, there is currently less research on the test method for the estimation of the state of charge of the power battery management system, and the calculation method for the estimation of the state of charge of the power battery management system is complex and has insufficient accuracy.

[0003] The above content is only used to assist in understanding the technical solutions of the present application and does not represent an acknowledgement that the above content is prior art. SUMMARY

[0004] The main purpose of the present application is to provide a test method, device and equipment for improving the estimation accuracy of the state of charge of a power battery, which aims to solve the technical problem of the complex calculation method and insufficient accuracy of the estimation of the state of charge of the power battery management system in the prior art.

[0005] To achieve the above purpose, the present application provides a test method for improving the estimation accuracy of the state of charge of a power battery, which is applied to a test system for improving the estimation accuracy of the state of charge of a power battery. The test system for improving the estimation accuracy of the state of charge of a power battery at least includes a thermostat, a power battery management system and a charge and discharge device. The power battery is placed in the thermostat, and the power battery management system and the charge and discharge device are respectively connected to the power battery. The charge and discharge device is used for charge and discharge test of the power battery and records the true value of the state of charge of the power battery in the charge and discharge test. The power battery management system is used for obtaining the BMS value of the state of charge of the power battery in the charge and discharge test. The test method for improving the estimation accuracy of the state of charge of a power battery includes:

[0006] After the temperature of the thermostat is adjusted to room temperature, the power battery is discharged at a constant current to a first state of charge and pulse constant current charged to a second state of charge to complete full discharge and full charge;

[0007] After the temperature of the thermostat is adjusted to a specific temperature, the power battery is discharged to a third state of charge after being placed for a period of time.

[0008] based on the third state of charge and the fourth state of charge, performing a charge-discharge cycle test on the power battery under a preset working condition;

[0009] after the charge-discharge cycle test is completed, discharging the power battery to the first state of charge to complete full discharge;

[0010] based on the state of charge true value recorded by the charge-discharge equipment in the charge-discharge test and the state of charge BMS value obtained by the power battery management system, determining a state of charge absolute error;

[0011] based on the state of charge absolute error, determining a state of charge evaluation result to improve the state of charge estimation accuracy of the power battery management system.

[0012] In an embodiment, after the temperature of the thermostat is adjusted to room temperature, the power battery is discharged to the first state of charge at a constant current and is pulse-constant-current charged to the second state of charge to complete the steps of full discharge and full charge, which include:

[0013] after the temperature of the thermostat is adjusted to room temperature, the power battery is discharged to the first state of charge at a constant current based on a first preset discharge rate to complete full discharge;

[0014] after full discharge is completed, the power battery is pulse-constant-current charged to the second state of charge based on a preset pulse current to complete full charge;

[0015] after full charge is completed, the power battery is subjected to a standing treatment based on a first standing time.

[0016] In an embodiment, after the temperature of the thermostat is adjusted to a specific temperature, the power battery that has completed standing is discharged to the third state of charge, which includes:

[0017] after the temperature of the thermostat is adjusted to a specific temperature, the power battery is subjected to a standing treatment based on a second standing time;

[0018] after the standing is completed, the power battery in the second state of charge is discharged to the third state of charge based on a second preset discharge rate.

[0019] In an embodiment, based on the third state of charge and the fourth state of charge, the power battery is subjected to a charge-discharge cycle test under a preset working condition, which includes:

[0020] under the preset working condition, the power battery is discharged to the fourth state of charge based on a third preset discharge rate and is subjected to a standing treatment based on a third standing time;

[0021] the power battery is charged to the third state of charge based on a fast charging strategy and is subjected to a standing treatment based on a fourth standing time;

[0022] The updating of the cycle number is repeated until the cycle number meets a preset cycle number.

[0023] In an embodiment, after the completion of the charge-discharge cycle test, the discharging of the power battery to the first state of charge to complete the full discharge includes:

[0024] After the completion of the charge-discharge cycle test, the power battery is discharged to the discharge cut-off voltage under a preset working condition based on a fourth preset discharge rate;

[0025] After the temperature of the thermostat is adjusted to room temperature, the power battery is subjected to a standing treatment based on a fifth standing time;

[0026] After the standing is completed, the power battery is discharged to the first state of charge based on a fifth preset discharge rate to complete the full discharge.

[0027] In an embodiment, based on the state of charge true value recorded by the charge-discharge device in the charge-discharge test and the state of charge BMS value obtained by the power battery management system, the step of determining the state of charge absolute error includes:

[0028] The charge-discharge current data and the charge-discharge time data recorded by the charge-discharge device are obtained, and based on the charge-discharge current data, the charge-discharge time data and the charge-discharge efficiency, the battery capacity data of the charge-discharge device is determined;

[0029] Based on the battery capacity data and the battery rated capacity, the state of charge true value is determined;

[0030] The state of charge BMS value obtained by the power battery management system is obtained, and the difference between the state of charge true value and the state of charge BMS value is taken as the state of charge absolute error.

[0031] In an embodiment, based on the charge-discharge current data, the charge-discharge time data and the charge-discharge efficiency, the step of determining the battery capacity data of the charge-discharge device includes:

[0032] The charge-discharge efficiency is obtained;

[0033] A first correspondence relationship between the charge-discharge current data, the charge-discharge time data, the charge-discharge efficiency and the battery capacity data is obtained;

[0034] Based on the charge-discharge current data, the charge-discharge time data, the charge-discharge efficiency and the first correspondence relationship, the battery capacity data is obtained.

[0035] In an embodiment, based on the battery capacity data and the battery rated capacity, the step of determining the state of charge true value includes:

[0036] A second correspondence relationship between the battery capacity data, the battery rated capacity and the state of charge true value is obtained;

[0037] determine the state of charge true value based on the battery capacity data, the battery rated capacity, and the second correspondence relationship.

[0038] In an embodiment, the state of charge absolute error includes a state of charge absolute error of the charge-discharge cycle test and a state of charge absolute error of the overall charge-discharge test; and based on the state of charge absolute error, the step of determining the state of charge evaluation result to improve the state of charge estimation accuracy of the power battery management system includes:

[0039] when the state of charge absolute error of the charge-discharge cycle test is greater than the preset error threshold, determining that the state of charge evaluation result of the charge-discharge cycle test is that the accuracy does not meet the requirement, and correcting the state of charge of the power battery management system to improve the state of charge estimation accuracy of the power battery management system;

[0040] when the state of charge absolute error of the overall charge-discharge test is greater than the preset error threshold, determining that the state of charge evaluation result of the overall charge-discharge test is that the accuracy does not meet the requirement, and correcting the state of charge of the power battery management system to improve the state of charge estimation accuracy of the power battery management system.

[0041] In addition, to achieve the above-mentioned purpose, the application further provides a test device for improving the state of charge estimation accuracy of a power battery, which comprises:

[0042] a test module, configured to discharge the power battery to a first state of charge and pulse constant-current charge the power battery to a second state of charge after the temperature of the thermostat is adjusted to room temperature, so as to complete full discharge and full charge;

[0043] the test module is further configured to discharge the power battery to a third state of charge after the temperature of the thermostat is adjusted to a specific temperature.

[0044] the test module is further configured to perform a charge-discharge cycle test on the power battery under a preset working condition based on the third state of charge and a fourth state of charge.

[0045] the test module is further configured to discharge the power battery to the first state of charge after the charge-discharge cycle test is completed, so as to complete full discharge.

[0046] an evaluation module, configured to determine a state of charge absolute error based on a state of charge true value recorded by a charge-discharge device in the charge-discharge test and a state of charge BMS value obtained by the power battery management system.

[0047] the evaluation module is further configured to determine a state of charge evaluation result based on the state of charge absolute error to improve the state of charge estimation accuracy of the power battery management system.

[0048] In addition, to achieve the above object, the application further provides a test device for improving the estimation accuracy of the state of charge of a power battery, which comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the computer program is configured to implement the steps of the test method for improving the estimation accuracy of the state of charge of the power battery.

[0049] In addition, to achieve the above object, the application further provides a storage medium, which is a computer readable storage medium, and the storage medium stores a computer program, and the computer program is executed by a processor to implement the steps of the test method for improving the estimation accuracy of the state of charge of the power battery.

[0050] In addition, to achieve the above object, the application further provides a computer program product, which comprises a computer program, and the computer program is executed by a processor to implement the steps of the test method for improving the estimation accuracy of the state of charge of the power battery.

[0051] The application provides a test method for improving the estimation accuracy of the state of charge of a power battery, after the temperature of a thermostat is adjusted to room temperature, the power battery is discharged at a constant current to a first state of charge, and is pulse constant current charged to a second state of charge, to complete full discharge and full charge; after the temperature of the thermostat is adjusted to a specific temperature, the power battery after static placement is discharged to a third state of charge; based on the third state of charge and the fourth state of charge, the power battery is subjected to a charge-discharge cycle test under a preset working condition; after the charge-discharge cycle test is completed, the power battery is discharged to the first state of charge to complete full discharge; based on the state of charge true value recorded by the charge-discharge equipment in the charge-discharge test and the state of charge BMS value obtained by the power battery management system, the state of charge absolute error is determined; based on the state of charge absolute error, the state of charge evaluation result is determined, to improve the state of charge estimation accuracy of the power battery management system. The application uses the state of charge true value obtained by the charge-discharge equipment in real time under the constant temperature and continuous charge-discharge working condition, determines the state of charge absolute error, determines the state of charge evaluation result based on the design threshold of the state of charge absolute error, performs real-time SOC correction, improves the state of charge estimation accuracy of the power battery management system, and the test method is simple and convenient, easy to operate, effectively saves the development cost, and solves the technical problems of complex calculation method and insufficient precision of the state of charge estimation of the power battery management system. BRIEF DESCRIPTION OF DRAWINGS

[0052] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the application and, together with the specification, serve to explain the principles of the application.

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those skilled in the art, the other drawings can be obtained based on these drawings without any creative effort.

[0054] Figure 1 The test method for improving the estimation accuracy of the state of charge of the power battery according to the present application is related to a test system structure schematic diagram for improving the estimation accuracy of the state of charge of the power battery.

[0055] Figure 2 The test method for improving the estimation accuracy of the state of charge of the power battery according to the present application is related to a test system structure schematic diagram for improving the estimation accuracy of the state of charge of the power battery.

[0056] Figure 3 The test method for improving the estimation accuracy of the state of charge of the power battery according to the present application is related to a test system structure schematic diagram for improving the estimation accuracy of the state of charge of the power battery.

[0057] Figure 4 The test method for improving the estimation accuracy of the state of charge of the power battery according to the present application is related to a test system structure schematic diagram for improving the estimation accuracy of the state of charge of the power battery.

[0058] Figure 5 The test method for improving the estimation accuracy of the state of charge of the power battery according to the present application is related to a test system structure schematic diagram for improving the estimation accuracy of the state of charge of the power battery.

[0059] Figure 6 The test method for improving the estimation accuracy of the state of charge of the power battery according to the present application is related to a test system structure schematic diagram for improving the estimation accuracy of the state of charge of the power battery.

[0060] Figure 7 The test method for improving the estimation accuracy of the state of charge of the power battery according to the present application is related to a test system structure schematic diagram for improving the estimation accuracy of the state of charge of the power battery.

[0061] Figure 8 The test method for improving the estimation accuracy of the state of charge of the power battery according to the present application is related to a test system structure schematic diagram for improving the estimation accuracy of the state of charge of the power battery.

[0062] Figure 9 The test method for improving the estimation accuracy of the state of charge of the power battery according to the present application is related to a test system structure schematic diagram for improving the estimation accuracy of the state of charge of the power battery.

[0063] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0064] It should be understood that the specific embodiments described herein merely serve to explain the technical solutions of the present application, and are not used to limit the present application.

[0065] In order to better understand the technical solutions of the present application, the following will be described in detail in combination with the drawings of the specification and specific embodiments.

[0066] The main solution of the embodiment of the present application is: after the temperature of the thermostat is adjusted to room temperature, the power battery is discharged at a constant current to a first state of charge, and is pulse constant current charged to a second state of charge, to complete full discharge and full charge; after the temperature of the thermostat is adjusted to a specific temperature, the power battery completed by standing is discharged to a third state of charge; based on the third state of charge and the fourth state of charge, the power battery is tested for charge and discharge cycle under a preset working condition; after the charge and discharge cycle test is completed, the power battery is discharged to the first state of charge to complete full discharge; based on the state of charge absolute error determined based on the state of charge true value recorded by the charge and discharge equipment and the state of charge BMS value obtained by the power battery management system during the charge and discharge test, the state of charge evaluation result is determined to improve the state of charge estimation accuracy of the power battery management system.

[0067] At present, there is less related research on the test method of the state of charge estimation of the power battery management system, and the calculation method of the state of charge estimation of the power battery management system is complex and has insufficient accuracy.

[0068] The present application provides a solution, under constant temperature and continuous charge and discharge working condition, the state of charge absolute error is determined by using the state of charge true value obtained by the charge and discharge equipment in real time, the state of charge evaluation result is determined based on the design threshold of the state of charge absolute error, the SOC is corrected in real time to improve the state of charge estimation accuracy of the power battery management system, and the test method is simple and convenient, easy to operate, effectively saves the development cost, and solves the technical problems of complex calculation method and insufficient accuracy of the state of charge estimation of the power battery management system.

[0069] It should be noted that the present embodiment is applied to a test system for improving the state of charge estimation accuracy of the power battery, and reference is made to Figure 1 The test system for improving the state of charge estimation accuracy of the power battery at least includes a thermostat 1, a power battery management system (BMS) 2, a charge and discharge equipment 3, a power battery 4 and a CAN bus 5, the power battery 4 is placed in the thermostat 1, and the power battery management system 2 and the charge and discharge equipment 3 are connected to the power battery 4 through the CAN bus 5 respectively.

[0070] It can be understood that the BMS can generally realize functions such as online monitoring of battery state, SOC estimation, battery health state analysis, and implementation of necessary thermal management, to ensure safe operation of the battery pack and prolong the cycle life of the battery. Illustratively, the BMS can collect the terminal voltage and temperature of each battery in the power battery pack of the electric vehicle, the charging and discharging current, and the total voltage of the battery pack in real time, to prevent overcharging or overdischarging of the battery; the BMS can balance the charging and discharging of the single batteries in the power battery pack, so that each battery in the battery pack reaches a balanced and consistent state; the BMS can analyze whether the SOC is too high, whether the battery temperature is too high / low, whether the voltage of the single battery is too high / low, whether the temperature rise of the battery is too fast, whether the insulation is faulty, whether the current is too high, the consistency of the battery, whether the battery pack is faulty, and whether the communication is faulty, etc.

[0071] In the present embodiment, the charge and discharge device 3 is used to perform charge and discharge tests on the power battery 4 and record the true value of the state of charge of the power battery 4 in the charge and discharge test, and the power battery management system 2 is used to obtain the state of charge BMS value of the power battery 4 in the charge and discharge test. The true value of the state of charge can generally be determined according to the data recorded by the charge and discharge device 3, and the state of charge BMS value, i.e., the SOC value estimated by the power battery management system 2, generally has a certain error with the true value of the state of charge. The CAN bus 5 is used to connect the power battery management system and the power battery, and also used to connect the charge and discharge device and the power battery, to realize data sharing and transmission.

[0072] Further, referring to Figure 2 , the test system for improving the estimation accuracy of the state of charge of the power battery can further include an oscilloscope, a power supply, a multimeter, a debugging bench, a CAN bus, a bus monitoring device, a notebook computer, etc., which are not specifically limited in the present embodiment. The CAN bus is used to connect the BMS battery management system and the notebook computer, for data transmission between the BMS and the notebook computer, to obtain the SOC value estimated by the BMS. The CAN bus is also used to connect the charge and discharge device and the power battery, to obtain the true value of the state of charge of the power battery.

[0073] The present application provides a test method for improving the estimation accuracy of the state of charge of the power battery, referring to Figure 3 , Figure 3 is a flowchart of the first embodiment of the test method for improving the estimation accuracy of the state of charge of the power battery of the present application.

[0074] In the present embodiment, the test method for improving the estimation accuracy of the state of charge of the power battery includes steps S10-S60:

[0075] Step S10, after the temperature of the thermostat is adjusted to room temperature, the power battery is discharged at a constant current to a first state of charge, and is pulse constant current charged to a second state of charge, to complete full discharge and full charge;

[0076] It should be noted that the entire charge and discharge test in this embodiment includes 12 stages, different stages usually need to perform different charge and discharge operations, and these charge and discharge operations can be realized by a charge and discharge device.

[0077] In addition, it should be noted that in this embodiment, under the condition of constant temperature and continuous charge and discharge, the test method is used to obtain the state of charge BMS value and the state of charge true value of the power battery management system, determine the state of charge evaluation result, and thus real-time SOC correction is performed to improve the state of charge estimation accuracy of the power battery management system.

[0078] In a feasible implementation, step S10 can include steps S101-S103:

[0079] Step S101, after the temperature of the thermostat is adjusted to room temperature, the power battery is discharged to a first state of charge based on a first preset discharge rate, so as to complete full discharge.

[0080] Generally, less than or equal to 1 / 3C is a low discharge rate, greater than 1 / 3C and less than 3C is a medium discharge rate, and greater than or equal to 3C is a high discharge rate.

[0081] It should be noted that the temperature of the thermostat is set to room temperature, which is usually 25°C, the first stage is a preparation stage, and the power battery needs to be fully discharged, and the constant current discharge mode is used in this embodiment. The first preset discharge rate is the discharge rate used in the first stage, and a lower discharge rate is selected in this embodiment, for example: 1 / 3C, that is, the size of the discharge current is 1 / 3 of the rated capacity of the battery, or other appropriate low discharge rates can also be selected, which are not limited. In this embodiment, the first state of charge is SOC equal to 0.

[0082] It can be understood that in the first stage, the power battery is discharged to SOC=0 at a discharge rate of 1 / 3C. In this process, since a low discharge rate is used, the polarization of the electrode is small, and the active material can be fully utilized, which is beneficial to the discharge process and can completely release the battery capacity, which is beneficial to the use safety and cycle life of the power battery.

[0083] Step S102, after full discharge is completed, the power battery is pulse constant current charged to a second state of charge based on a preset pulse current, so as to complete full charge.

[0084] It should be noted that the full charging is completed, and the second stage is entered, and the second stage to the twelfth stage is a test stage, and the power battery needs to be fully charged in the second stage, and the pulse constant current charging mode is adopted in the embodiment. The preset pulse current is the pulse current used in the second stage, which can be set according to actual needs, and is not limited specifically. In the embodiment, the second state of charge is SOC equal to 100%, that is, the full charging state.

[0085] In addition, it should be noted that referring to Figure 4 , the pulse constant current charging usually sets a plurality of charging periods T, each charging period T is provided with a pulse duration T1 and a pulse interval time T2, the pulse duration T1 indicates that the preset pulse current I is used to charge the battery with constant current, and the pulse interval time T2 indicates that the battery stops charging, that is, the preset pulse current is used to charge the battery with pulse constant current, the charging time is T1, then the battery stops charging, the stop charging time is T2, then the preset pulse current is used to charge the battery with pulse constant current, the charging time is T1, and then the battery stops charging, the stop charging time is T2, and the cycle is repeated. In this process, the pulse constant current charging makes the power battery fully charged, and the pulse interval time makes the concentration of the electrolyte balanced, the charge on the electrode balanced, and the battery polarization phenomenon (including ohmic polarization, concentration polarization and electrochemical polarization) eliminated, thereby reducing the pressure inside the power battery, so that the next round of constant current charging can be carried out more smoothly, the power battery can absorb more electricity, and the charging efficiency is improved.

[0086] It can be understood that in the second stage, the power battery is charged with pulse constant current to SOC=100% with the preset pulse current.

[0087] Step S103, after the full charging is completed, the power battery is subjected to a static treatment based on a first static time.

[0088] It should be noted that the full charging is completed, and the third stage is entered, and the third stage needs to be static to the power battery. The first static time is the time required for the static treatment in the third stage, and the first static time usually needs to be greater than or equal to 30 minutes, which can be flexibly adjusted according to actual needs, and is not limited specifically.

[0089] It can be understood that in the third stage, the BMS power supply is disconnected within 1 min after full charging, and is static for more than 30 min, then the BMS power supply is connected, the BMS data and the charging and discharging equipment data in the static time are recorded, the SOC is adjusted to 100%, and the BMS power supply is disconnected within 1 min, and is static. The static treatment can eliminate the polarization effect of the electrode, and correct and adjust the SOC to 100%, thereby improving the state of charge estimation accuracy of the power battery management system.

[0090] It should be noted that the BMS data and the charging and discharging equipment data can include the temperature of the battery, the charging and discharging current, the charging and discharging time, the true value of the state of charge, the BMS value of the state of charge, and the like.

[0091] It should be understood that the temperature of the incubator in the first phase to the third phase needs to be adjusted to room temperature, which can be usually set to 25℃, or other values according to actual needs, which are not limited in the embodiment.

[0092] In step S20, after the temperature of the incubator is adjusted to the specific temperature, the power battery which is completed with the static treatment is discharged to the third state of charge.

[0093] In an available embodiment, step S20 can include steps S201-S202.

[0094] In step S201, after the temperature of the incubator is adjusted to the specific temperature, the power battery is treated with the static treatment based on the second static time.

[0095] It should be noted that after the static treatment in the third phase is completed, the fourth phase is entered, and the power battery needs to be treated with the static treatment at the specific temperature, so the temperature of the incubator needs to be adjusted to the specific temperature. The specific temperature is the temperature corresponding to the constant temperature working condition which needs to be tested in the embodiment, which is usually set in the normal working temperature range of the power battery, for example, the normal working temperature range of the power battery is -20℃-45℃, and the specific temperature can be set to 25℃, which is not limited.

[0096] In addition, it should be noted that the second static time is the time required for the static treatment in the fourth phase, which usually needs to be greater than or equal to 8 hours, so that the temperature of the power battery and the ambient temperature of the incubator can reach a temperature equilibrium state (the temperature difference between the temperature of the power battery and the specific temperature is not greater than 2℃), on the other hand, the static treatment can eliminate the polarization of the power battery.

[0097] It can be understood that in the fourth phase, the temperature of the incubator is adjusted to the specific temperature, and the power battery continues to be treated with the static treatment for at least 8 hours.

[0098] In step S202, after the static treatment is completed, the power battery in the second state of charge is discharged to the third state of charge based on the second preset discharge rate.

[0099] It should be noted that the fourth stage is completed to enter the fifth stage, and the fifth stage needs to discharge the power battery. The second preset discharge rate is the discharge rate used in the fifth stage. In the embodiment, a lower discharge rate is selected, for example: 1 / 3C, and other appropriate discharge rates can also be selected. When the specific temperature is at subzero low temperature, a lower discharge rate needs to be used, which is not specifically limited. In the embodiment, the third state of charge is SOC equal to 80%.

[0100] It can be understood that in the fifth stage, the BMS power supply is turned on, and the full-charged power battery is discharged to SOC=80% at a discharge rate of 1 / 3C.

[0101] Step S30, based on the third state of charge and the fourth state of charge, the power battery is subjected to charge-discharge cycle test under the preset working condition;

[0102] It should be noted that the preset working condition is NEDC / WLTC working condition, wherein NEDC (New European Driving Cycle) is a European endurance test standard, and WLTC (Worldwide Harmonized Light Vehicles Test Cycle) is a new type of cycle test standard formulated by the United Nations.

[0103] In addition, it should be noted that after the fifth stage is completed, the sixth stage to the ninth stage is entered, and in the embodiment, the sixth stage to the ninth stage is subjected to charge-discharge cycle test, that is, the charge-discharge operation of the sixth stage to the ninth stage needs to be performed multiple times according to the set cycle number.

[0104] In a feasible implementation manner, step S30 can include steps S301-S303:

[0105] Step S301, under the preset working condition, the power battery is discharged to the fourth state of charge based on the third preset discharge rate, and the power battery is subjected to static treatment based on the third static time;

[0106] It should be noted that the sixth stage needs to discharge the power battery. The third preset discharge rate is the discharge rate used in the sixth stage. In the embodiment, a lower discharge rate is selected, for example: 1 / 3C, and other appropriate discharge rates can also be selected. When the specific temperature is at subzero low temperature, a lower discharge rate needs to be used, which is not specifically limited. In the embodiment, the fourth state of charge is SOC equal to 30%.

[0107] Additionally, it should be noted that the seventh stage requires the power battery to be stationary, and the third stationary time, i.e., the duration required for the stationary treatment in the seventh stage, is usually greater than or equal to 30 minutes.

[0108] It can be understood that, in the sixth stage to the seventh stage, the power battery is discharged to SOC=30% at a discharge rate of 1 / 3C under the NEDC / WLTC working condition, the BMS data and the charge-discharge equipment data in the discharging process are recorded, the BMS power supply is disconnected within 1 minute, and the power battery is stationary for more than half an hour.

[0109] In step S302, the power battery is charged to a third state of charge based on a fast charging strategy, and the power battery is stationary based on a fourth stationary time;

[0110] It should be noted that after the stationary of the seventh stage is completed, the eighth stage is entered, and the power battery needs to be charged to SOC=80%. The fast charging strategy is a fast charging mode. In this embodiment, the fast charging mode is selected to maximize the chemical reaction speed of the power battery, shorten the charging time of the power battery, and at the same time, minimize or reduce the polarization phenomenon of the positive and negative plates of the power battery, thereby improving the use efficiency and cycle life of the power battery. In specific implementation, the variable current intermittent charging method can be used, or the fast charging mode can be flexibly adjusted according to actual needs to make the charging curve as close to the optimal charging curve as possible.

[0111] It can be understood that, in the eighth stage, the BMS power supply is turned on, the BMS data and the charge-discharge equipment data in the stationary time are recorded, the power battery is charged to SOC=80% by using the fast charging strategy, and the BMS data and the charge-discharge equipment data in the charging process are recorded.

[0112] Exemplarily, referring to Figure 5 The variable current intermittent charging method is based on constant current charging and pulse charging. First, a large current constant current charging is performed, and then the charging is stopped when the battery voltage rises to the cutoff voltage. Then, a smaller current is used for charging, that is, a variable pulse current charging is used, which takes into account the effects of fast charging in the initial charging stage and pulse charging depolarization. The characteristic is that the constant current charging section is changed to a variable current intermittent charging section. The method of variable current intermittent charging is used in each section in the early charging stage to obtain most of the charging capacity. The constant voltage charging section is used in the later charging stage to obtain overcharging capacity and restore the battery to a fully charged state. By intermittent stopping charging, the polarization effect (including electrochemical polarization, concentration polarization, and ohmic polarization) of the power battery is eliminated, thereby reducing the internal pressure of the power battery, enabling the next round of charging to be more smoothly performed, and enabling the storage battery to absorb more electric capacity.

[0113] Additionally, it should be noted that the ninth stage needs to be placed on the power battery, and the fourth standing time is the time required for the standing treatment of the ninth stage. The fourth standing time usually needs to be greater than or equal to 30 minutes.

[0114] It can be understood that in the ninth stage, the BMS power supply is disconnected, and the BMS power supply is connected within 1 minute. The BMS data and the charge and discharge equipment data during the standing time are recorded.

[0115] In step S303, the cycle number is updated, and the above steps are repeatedly executed until the cycle number meets the preset cycle number.

[0116] It can be understood that the cycle number + 1 is completed after each round of charge and discharge operation of the sixth stage to the ninth stage. The preset cycle number is the number of cycles set, for example: 10 times. When the cycle number reaches 10 times, the charge and discharge cycle test is completed. When the cycle number does not reach 10 times, the next round of charge and discharge operation is continued.

[0117] In step S40, after the completion of the charge and discharge cycle test, the power battery is discharged to the first state of charge to complete the full discharge.

[0118] In one possible implementation, step S40 can include steps S401-S403.

[0119] In step S401, after the completion of the charge and discharge cycle test, the power battery is discharged to the discharge cut-off voltage under the preset working condition based on the fourth preset discharge rate.

[0120] It should be noted that after the completion of the charge and discharge cycle test, the tenth stage is entered, and the fourth preset discharge rate is the discharge rate used in the tenth stage. In this embodiment, a lower discharge rate is selected, for example: 1 / 3C. Other suitable discharge rates can also be selected. When the specific temperature is at a low temperature below zero, a lower discharge rate needs to be used, which is not limited here.

[0121] It can be understood that in the tenth stage, the BMS power supply is connected, and the power battery is discharged to the discharge cut-off voltage at a discharge rate of 1 / 3C under the NEDC / WLTC working condition.

[0122] It should be understood that the fourth stage to the tenth stage are all carried out at a specific temperature.

[0123] In step S402, after the temperature of the thermostat is adjusted to room temperature, the power battery is placed based on the fifth standing time.

[0124] It should be noted that the next step is the eleventh stage, which needs to set the temperature of the thermostat to room temperature, usually 25°C, and the power battery needs to be placed. The fifth standing time, i.e. the duration of the eleventh stage standing treatment, usually needs to be greater than or equal to 8 hours, so that the temperature of the power battery and the ambient temperature of the thermostat reach a balanced state (the temperature difference between the power battery and the room temperature is not greater than 2°C), on the other hand, standing can eliminate the polarization of the power battery.

[0125] It can be understood that in the eleventh stage, the temperature of the thermostat is set to 25°C, the BMS power supply is disconnected within 1 min, and the power battery is placed for more than 8 hours.

[0126] Step S403, after standing, discharge the power battery to the first state of charge based on the fifth preset discharge rate to complete the full discharge.

[0127] It should be noted that after the eleventh stage of standing is completed, the twelfth stage is entered, and in order to ensure the full discharge of the power battery, the twelfth stage needs to continue discharging. The fifth preset discharge rate is the discharge rate used in the twelfth stage. In order to avoid the situation that the SOC is 0 in advance, but the battery discharge cutoff voltage is not triggered, low rate current discharge should be used to reduce polarization, which is beneficial to the battery discharge process and completes the full discharge. Therefore, this embodiment selects a lower discharge rate, for example: 0.05C, other appropriate low discharge rates can also be selected, which are not limited in particular.

[0128] It can be understood that in the twelfth stage, the BMS power supply is connected, and the power battery is discharged to SOC=0 at a discharge rate of 0.05C. The BMS data and the charge and discharge equipment data during the discharge process are recorded.

[0129] Step S50, based on the state of charge true value recorded by the charge and discharge equipment in the charge and discharge test and the state of charge BMS value obtained by the power battery management system, determine the state of charge absolute error;

[0130] It should be noted that the state of charge absolute error is the error between the state of charge true value recorded by the charge and discharge equipment in the charge and discharge test and the state of charge BMS value obtained by the power battery management system. It can be seen that in order to ensure the accuracy of the state of charge estimation of the BMS, the state of charge absolute error usually cannot exceed a certain value.

[0131] Step S60, based on the state of charge absolute error, determine the state of charge evaluation result, to improve the state of charge estimation accuracy of the power battery management system.

[0132] It should be noted that the state of charge evaluation result, i.e. the case of evaluating the state of charge estimation accuracy of the power battery management system, usually has two cases: the accuracy meets the requirements and the accuracy does not meet the requirements. The state of charge absolute error includes the state of charge absolute error of the charge-discharge cycle test and the state of charge absolute error of the overall charge-discharge test, wherein the overall charge-discharge test refers to the entire charge-discharge test process. Based on the state of charge absolute error of the charge-discharge cycle test, the embodiment can determine the state of charge evaluation result in the charge-discharge cycle test. Based on the state of charge absolute error of the overall charge-discharge test, the embodiment can determine the state of charge evaluation result in the overall charge-discharge test.

[0133] In a feasible implementation, when the state of charge absolute error of the charge-discharge cycle test is greater than the preset error threshold, it is determined that the state of charge evaluation result of the charge-discharge cycle test is that the accuracy does not meet the requirements, and the state of charge of the power battery management system is corrected to improve the state of charge estimation accuracy of the power battery management system.

[0134] It should be noted that the preset error threshold is the design threshold of the state of charge absolute error, that is, the state of charge absolute error needs to be less than or equal to the preset error threshold. For different battery types, material systems, battery designs, manufacturing processes, and specific conditions of tests, the preset error threshold is different, which can be flexibly adjusted according to specific conditions to ensure the performance and safety of the battery, and no specific limitation is made, and exemplarily, the preset error threshold of the ternary lithium type power battery is set to 3%, and the preset error threshold of the lithium iron phosphate type power battery is set to 5%.

[0135] It can be understood that when the state of charge absolute error of the charge-discharge cycle test is greater than the preset error threshold, it indicates that the state of charge evaluation result of the charge-discharge cycle test is that the accuracy does not meet the requirements, at this time, the SOC of the power battery management system needs to be corrected, and the correction event is recorded for debugging analysis, so as to improve the state of charge estimation accuracy of the power battery management system. The correction can be performed during the static period. When the state of charge absolute error of the charge-discharge cycle test is less than or equal to the preset error threshold, it indicates that the state of charge evaluation result of the charge-discharge cycle test is that the accuracy meets the requirements.

[0136] In a feasible implementation, when the state of charge absolute error of the overall charge-discharge test is greater than the preset error threshold, it is determined that the state of charge evaluation result of the overall charge-discharge test is that the accuracy does not meet the requirements, and the state of charge of the power battery management system is corrected to improve the state of charge estimation accuracy of the power battery management system.

[0137] It can be understood that the absolute error of the state of charge of the overall charging and discharging test is greater than the preset error threshold, which indicates that the state of charge evaluation result of the overall charging and discharging test does not meet the accuracy requirement, at which time the SOC of the power battery management system needs to be corrected, and the correction event is recorded for debugging analysis, so as to improve the state of charge estimation accuracy of the power battery management system. The correction can be performed during the static period. The absolute error of the state of charge of the overall charging and discharging test is less than or equal to the preset error threshold, which indicates that the state of charge evaluation result of the overall charging and discharging test meets the accuracy requirement.

[0138] It should be understood that the present embodiment can set a plurality of specific temperatures, and the state of charge evaluation result is determined for each specific temperature by performing the charging and discharging test, so as to further improve the state of charge estimation accuracy of the power battery management system. The plurality of specific temperatures are all set within the normal working temperature range of the power battery.

[0139] The present embodiment provides a test method for improving the state of charge estimation accuracy of a power battery. After the temperature of the thermostat is adjusted to room temperature, the power battery is discharged at a constant current to a first state of charge, and is pulse-constant-current charged to a second state of charge, so as to complete full discharge and full charge. After the temperature of the thermostat is adjusted to a specific temperature, the power battery after the static period is discharged to a third state of charge. Based on the third state of charge and the fourth state of charge, the power battery is tested by charging and discharging under a preset working condition. After the charging and discharging cycle test is completed, the power battery is discharged to the first state of charge, so as to complete full discharge. Based on the true value of the state of charge recorded by the charging and discharging equipment and the state of charge BMS value obtained by the power battery management system, the absolute error of the state of charge is determined. Based on the absolute error of the state of charge, the state of charge evaluation result is determined, so as to improve the state of charge estimation accuracy of the power battery management system. Under the constant temperature and continuous charging and discharging working condition, the true value of the state of charge obtained by the charging and discharging equipment in real time is used to determine the absolute error of the state of charge, the state of charge evaluation result is determined based on the design threshold of the absolute error of the state of charge, the SOC is corrected in real time, so as to improve the state of charge estimation accuracy of the power battery management system. The test method is simple and convenient, easy to operate, and effectively saves the development cost.

[0140] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar contents as the above-mentioned first embodiment can be referred to the above introduction, and will not be described in detail. On this basis, please refer to Figure 6 , step S50 can include steps S501-S503:

[0141] In step S501, the charging and discharging current data and the charging and discharging time data recorded by the charging and discharging equipment are obtained, and the battery capacity data of the charging and discharging equipment is determined based on the charging and discharging current data, the charging and discharging time data and the charging and discharging efficiency;

[0142] It should be noted that, since the constant temperature, continuous charging and discharging conditions are tested in the embodiment, it can be considered that the actual capacity of the battery is only affected by the charging and discharging efficiency.

[0143] In a possible implementation, the step S501 can include steps S5011-S5013.

[0144] In step S5011, the charging and discharging efficiency is obtained.

[0145] It should be noted that the charging and discharging efficiency can be obtained according to test and data analysis. In different charging and discharging modes, the charging and discharging cycle test is carried out, and the test time, voltage and current, battery capacity, battery capacity retention rate, charging and discharging capacity and other data are recorded. The experimental data is fitted / regressed by using statistical method (such as least square method), the performance and state of the battery are analyzed, and the charging and discharging efficiency of the battery is evaluated and determined. It can be understood that the charging and discharging efficiency of the power battery is different for different battery types, material systems, battery design, manufacturing process and specific test conditions. Therefore, in actual application, it needs to be flexibly adjusted according to the specific situation to ensure the performance and safety of the battery, and no specific limitation is made.

[0146] In step S5012, a first correspondence relationship between the charging and discharging current data, the charging and discharging time data, the charging and discharging efficiency and the battery capacity data is obtained.

[0147] It should be noted that the first correspondence relationship between the charging and discharging current data, the charging and discharging time data, the charging and discharging efficiency and the battery capacity data is as follows:

[0148]

[0149] In the formula, C t is the battery capacity data recorded by the charging and discharging equipment at time t, η is the charging and discharging efficiency, I(t) is the charging and discharging current of the power battery, which is a function of the charging and discharging time, the positive value represents charging, the negative value represents discharging, t0 is the initial time, and t is the current time.

[0150] In step S5013, the battery capacity data is obtained based on the charging and discharging current data, the charging and discharging time data, the charging and discharging efficiency and the first correspondence relationship.

[0151] It can be understood that the charging and discharging current data, the charging and discharging time data and the charging and discharging efficiency are substituted into the above first correspondence relationship, and the corresponding battery capacity data can be calculated.

[0152] In step S502, the real value of the state of charge is determined based on the battery capacity data and the rated capacity of the battery.

[0153] In one possible implementation, step S502 can include steps S5021-S5022:

[0154] Step S5021, obtaining a second correspondence relationship between the battery capacity data, the battery rated capacity and the real value of the state of charge;

[0155] It should be noted that the second correspondence relationship between the battery capacity data, the battery rated capacity and the real value of the state of charge is as follows:

[0156]

[0157] In the formula, SOC true is the real value of the state of charge, C t is the battery capacity data, C rated is the battery rated capacity.

[0158] Step S5022, determining the real value of the state of charge based on the battery capacity data, the battery rated capacity and the second correspondence relationship.

[0159] It can be understood that the battery capacity data, the battery rated capacity are substituted into the above-mentioned second correspondence relationship, and the corresponding real value of the state of charge can be calculated.

[0160] Step S503, obtaining the state of charge BMS value obtained by the power battery management system, and taking the difference between the real value of the state of charge and the state of charge BMS value as the absolute error of the state of charge.

[0161] It can be understood that the difference between the real value of the state of charge and the state of charge BMS value is the absolute error of the state of charge, which is as follows:

[0162]

[0163] In the formula, DEV ABS is the absolute error of the state of charge, SOC BSM is the state of charge BMS value, SOC true is the real value of the state of charge, C rated is the battery rated capacity, η is the charging and discharging efficiency, I(t) is the charging and discharging current of the power battery, which is a function of the charging and discharging time, the positive value represents charging, and the negative value represents discharging, t0 is the initial time, and t is the current time.

[0164] Exemplarily, assuming that the overall charging and discharging test is t1-t6, t0=t1, t=t6, At this time, the absolute error of the state of charge is:

[0165]

[0166] Exemplarily, assuming that the charge and discharge cycle test is t2-t4, t0=t2, t=t4, At this time, the absolute error of the state of charge is:

[0167]

[0168] The embodiment provides a test method for improving the state of charge estimation accuracy of a power battery. Under a constant temperature and continuous charge and discharge working condition, a state of charge absolute error is determined by using a real value of the state of charge obtained by a charge and discharge device in real time, a state of charge evaluation result is determined based on a design threshold of the state of charge absolute error, and SOC correction is performed in real time, so that the state of charge estimation accuracy of a power battery management system is improved. The test method is simple, convenient and easy to operate, and development cost is effectively saved.

[0169] Exemplarily, in order to help understand the implementation process of the test method for improving the state of charge estimation accuracy of a power battery obtained by combining the above-mentioned embodiment two, please refer to Figure 7 , Figure 7 A brief flowchart of the test method for improving the state of charge estimation accuracy of a power battery is provided, and specifically:

[0170] (1) Preparation stage: 0-t0 stage, place the power battery in a 25 DEG C constant temperature oven, and discharge at a discharge rate of 1 / 3 C to SOC=0, at this time, t0 is recorded;

[0171] (2) t0-t1 stage of the test stage: using a pulse constant current charging method, full charging is completed, SOC=100%, at this time, t1 is recorded;

[0172] (3) t1-t2 stage of the test stage: at t1, the BMS power supply is disconnected within 1 min after full charging, and is placed for more than 30 min, the BMS power supply is connected, the BMS data and the charge and discharge device data during the standing time are recorded, the SOC is adjusted to 100%, the BMS power supply is disconnected within 1 min, and is placed, at this time, t2 is recorded;

[0173] (4) t2-t3 stage of the test stage: at t2, the temperature of the constant temperature oven is set to a specific temperature (for example, 25 DEG C), and the power battery continues to be placed in the constant temperature oven, at this time, t3 is recorded, and t3-t2 is greater than or equal to 8 hours;

[0174] (5) t3-t4 stage of the test stage: at t3, the BMS power supply is connected, and the power battery after full charging is discharged at a discharge rate of 1 / 3 C to SOC=80%, at this time, t4 is recorded;

[0175] (6) t4-t6 stage of the test stage: running in NEDC / WLTC operating condition, discharging to SOC=30% at 1 / 3C discharge rate, at this time t5 is recorded, recording BMS data and charging and discharging equipment data in the discharging process, disconnecting BMS power supply within 1 min, standing for more than half an hour, at this time t6 is recorded;

[0176] (7) t6-t8 stage of the test stage: at t6, connecting BMS power supply, recording BMS data and charging and discharging equipment data in the standing time, charging the power battery to SOC=80% in the fast charging mode, recording BMS data and charging and discharging equipment data in the charging process, at this time t7 is recorded, disconnecting BMS power supply within 1 min, standing for half an hour, at this time t8 is recorded, connecting BMS power supply, recording BMS data and charging and discharging equipment data in the standing time;

[0177] (8) repeating steps 6-7, continuing to cycle for 9 times, after 10 times of cycling, recording BMS data and charging and discharging equipment data;

[0178] (9) flexibly selecting whether to calculate the state of charge absolute error according to the actual situation, the state of charge absolute error can be used to determine whether the state of charge estimation accuracy of the power battery management system in the cycling test process meets the requirements, so as to perform real-time SOC correction;

[0179] (10) t8-t9 stage of the test stage: at t8, connecting BMS power supply, running in NEDC / WLTC operating condition, discharging the power battery to the discharge cut-off voltage at 1 / 3C discharge rate, at this time t9 is recorded;

[0180] (11) t9-t10 stage of the test stage: at t9, setting the temperature of the constant temperature box to 25℃ room temperature, disconnecting BMS power supply within 1 min, the power battery standing for more than 8h, at this time t10 is recorded;

[0181] (12) t10-t11 stage of the test stage: connecting BMS power supply, discharging the power battery to SOC=0 at 0.05C discharge rate, recording BMS data and charging and discharging equipment data in the discharging process, at this time t11 is recorded;

[0182] (13) calculating the state of charge absolute error, the state of charge absolute error can be used to determine whether the state of charge estimation accuracy of the power battery management system in the whole test process meets the requirements, so as to perform real-time SOC correction;

[0183] (14) set the specific temperature of the thermostat to other temperatures, for example: -10℃, 0℃, 25℃, 45℃, the specific temperature is set in the normal working temperature range of the power battery, repeat the above steps, complete the test of improving the state of charge estimation accuracy of the power battery management system under multiple specific temperatures and continuous charging and discharging conditions.

[0184] The application also provides a test device for improving the state of charge estimation accuracy of a power battery, please refer to Figure 8 The test device for improving the state of charge estimation accuracy of a power battery comprises:

[0185] The test module 10 is used for discharging the power battery to a first state of charge and charging the power battery to a second state of charge after adjusting the temperature of the thermostat to room temperature, so as to complete full discharge and full charge.

[0186] The test module 10 is also used for discharging the power battery to a third state of charge after adjusting the temperature of the thermostat to a specific temperature.

[0187] The test module 10 is also used for performing charging and discharging cycle test on the power battery under a preset condition based on the third state of charge and a fourth state of charge.

[0188] The test module 10 is also used for discharging the power battery to the first state of charge after completing the charging and discharging cycle test, so as to complete full discharge.

[0189] The evaluation module 20 is used for determining the absolute error of the state of charge based on the true value of the state of charge recorded by the charging and discharging equipment in the charging and discharging test and the state of charge BMS value obtained by the power battery management system.

[0190] The evaluation module 20 is also used for determining the evaluation result of the state of charge based on the absolute error of the state of charge, so as to improve the state of charge estimation accuracy of the power battery management system.

[0191] In a feasible implementation, the test module 10 is also used for discharging the power battery to the first state of charge based on a first preset discharge rate after adjusting the temperature of the thermostat to room temperature, so as to complete full discharge.

[0192] After completing full discharge, the power battery is pulse constant current charged to the second state of charge based on a preset pulse current, so as to complete full charge.

[0193] After completing full charge, the power battery is subjected to static treatment based on a first static time.

[0194] In a feasible implementation, the test module 10 is also used for subjecting the power battery to static treatment based on a second static time after adjusting the temperature of the thermostat to a specific temperature.

[0195] After the static treatment is completed, the power battery is discharged to a third state of charge based on a second preset discharge rate.

[0196] In an implementable embodiment, the test module 10 is further configured to discharge the power battery to a fourth state of charge based on a third preset discharge rate under the preset working condition, and perform a static treatment on the power battery based on a third static treatment time.

[0197] The power battery is charged to the third state of charge based on a fast charging strategy, and a static treatment is performed on the power battery based on a fourth static treatment time.

[0198] The cycle number is updated, and the above steps are repeated until the cycle number meets a preset cycle number.

[0199] In an implementable embodiment, the test module 10 is further configured to, after the charge-discharge cycle test is completed, discharge the power battery to a discharge cut-off voltage based on a fourth preset discharge rate under the preset working condition.

[0200] After the temperature of the thermostat is adjusted to room temperature, a static treatment is performed on the power battery based on a fifth static treatment time.

[0201] After the static treatment is completed, the power battery is discharged to the first state of charge based on a fifth preset discharge rate to complete full discharge.

[0202] In an implementable embodiment, the evaluation module 20 is further configured to obtain charge-discharge current data and charge-discharge time data recorded by the charge-discharge device, and determine battery capacity data of the charge-discharge device based on the charge-discharge current data, the charge-discharge time data, and the charge-discharge efficiency.

[0203] Based on the battery capacity data and the rated capacity of the battery, a true value of the state of charge is determined.

[0204] A difference between the true value of the state of charge and a state of charge BMS value obtained by the power battery management system is taken as an absolute error of the state of charge.

[0205] In an implementable embodiment, the evaluation module 20 is further configured to obtain the charge-discharge efficiency.

[0206] A first correspondence relationship between the charge-discharge current data, the charge-discharge time data, the charge-discharge efficiency, and the battery capacity data is obtained.

[0207] Based on the charge-discharge current data, the charge-discharge time data, the charge-discharge efficiency, and the first correspondence relationship, the battery capacity data is obtained.

[0208] In an implementable embodiment, the evaluation module 20 is further configured to acquire battery capacity data, a second correspondence relationship between the battery rated capacity and the true value of the state of charge;

[0209] Based on the battery capacity data, the battery rated capacity and the second correspondence relationship, the true value of the state of charge is determined.

[0210] In an implementable embodiment, the evaluation module 20 is further configured to, when the absolute error of the state of charge in the charge-discharge cycle test is greater than a preset error threshold, determine that the evaluation result of the state of charge in the charge-discharge cycle test is that the accuracy does not meet the requirement, and correct the state of charge of the power battery management system to improve the accuracy of the state of charge estimation of the power battery management system.

[0211] When the absolute error of the state of charge in the charge-discharge overall test is greater than a preset error threshold, it is determined that the evaluation result of the state of charge in the charge-discharge overall test is that the accuracy does not meet the requirement, and the state of charge of the power battery management system is corrected to improve the accuracy of the state of charge estimation of the power battery management system.

[0212] The test device for improving the accuracy of the state of charge estimation of the power battery provided in the present application adopts the test method for improving the accuracy of the state of charge estimation of the power battery in the above-mentioned embodiments, and can solve the technical problems of the complex calculation method and insufficient accuracy of the state of charge estimation of the power battery management system. Compared with the prior art, the test device for improving the accuracy of the state of charge estimation of the power battery provided in the present application has the same beneficial effects as the test method for improving the accuracy of the state of charge estimation of the power battery provided in the above-mentioned embodiments, and the other technical features in the test device for improving the accuracy of the state of charge estimation of the power battery are the same as the features disclosed in the above-mentioned embodiments, and will not be repeated here.

[0213] The present application provides a test device for improving the accuracy of the state of charge estimation of the power battery, which comprises at least one processor and a memory in communication connection with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the test method for improving the accuracy of the state of charge estimation of the power battery in the above-mentioned embodiment one.

[0214] Reference will be made to the following Figure 9This document illustrates a schematic diagram of a test device suitable for improving the accuracy of power battery state-of-charge estimation in the embodiments of this application. The test device for improving the accuracy of power battery state-of-charge estimation in the embodiments of this application may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 9 The test equipment shown to improve the accuracy of power battery state of charge estimation is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0215] like Figure 9 As shown, the test equipment for improving the accuracy of power battery state-of-charge estimation may include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 1002 or a program loaded from storage device 1003 into random access memory (RAM) 1004. The RAM 1004 also stores various programs and data required for the operation of the test equipment for improving the accuracy of power battery state-of-charge estimation. The processing unit 1001, ROM 1002, and RAM 1004 are interconnected via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the test equipment for improving the accuracy of power battery state-of-charge estimation to communicate wirelessly or wiredly with other devices to exchange data. Although the figure shows a test equipment for improving the accuracy of power battery state-of-charge estimation with various systems, it should be understood that it is not required to implement or possess all the systems shown. More or fewer systems can be implemented alternatively.

[0216] In particular, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product comprising a computer program carried on a computer readable medium, the computer program containing program code for executing the method shown in the flowchart. In such embodiments, the computer program can be downloaded and installed from a network through a communication device, or installed from the storage device 1003, or installed from the ROM 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the method of the embodiments disclosed in the present application are executed.

[0217] The test device for improving the estimation accuracy of the state of charge of the power battery provided in the present application adopts the test method for improving the estimation accuracy of the state of charge of the power battery in the above-mentioned embodiments, and can solve the technical problems of complex calculation method and insufficient precision of the state of charge estimation of the power battery management system. Compared with the prior art, the test device for improving the estimation accuracy of the state of charge of the power battery provided in the present application has the same beneficial effects as the test method for improving the estimation accuracy of the state of charge of the power battery provided in the above-mentioned embodiments, and other technical features in the test device for improving the estimation accuracy of the state of charge of the power battery are the same as the features disclosed in the previous embodiment method, which will not be repeated here.

[0218] It should be understood that parts of the present application can be realized by hardware, software, firmware or a combination thereof. In the description of the above-mentioned embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0219] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0220] The present application provides a computer readable storage medium having stored thereon computer readable program instructions (i.e. computer program) for executing the test method for improving the estimation accuracy of the state of charge of the power battery in the above-mentioned embodiments.

[0221] The computer readable storage medium provided in the application may be, for example, a U disk, but is not limited to an electric, magnetic, optical, electromagnetic, infrared, or semiconductor system, system, or device, or any combination of the above. More specific examples of the computer readable storage medium may include, but are not limited to, an electric connection with one or more conductive wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present embodiment, the computer readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer readable storage medium can be transmitted by any suitable medium, including but not limited to an electric wire, an optical cable, an RF (Radio Frequency), and the like, or any suitable combination of the above.

[0222] The computer readable storage medium described above carries one or more programs, which, when executed by the test device for improving the estimation accuracy of the state of charge of the power battery, cause the test device for improving the estimation accuracy of the state of charge of the power battery to: after the temperature of the thermostat is adjusted to room temperature, discharge the power battery at a constant current to a first state of charge, and pulse constant current charge to a second state of charge to complete full discharge and full charge; after the temperature of the thermostat is adjusted to a specific temperature, discharge the power battery at rest to a third state of charge; based on the third state of charge and the fourth state of charge, perform a charge-discharge cycle test on the power battery under a predetermined working condition; after the charge-discharge cycle test is completed, discharge the power battery to the first state of charge to complete full discharge; based on the true value of the state of charge recorded by the charge-discharge equipment in the charge-discharge test and the state of charge BMS value obtained by the power battery management system, determine the absolute error of the state of charge; based on the absolute error of the state of charge, determine the evaluation result of the state of charge to improve the estimation accuracy of the state of charge of the power battery management system.

[0223] Computer program code for carrying out operations of the present application can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0224] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0225] The readable storage medium provided by the present application is a computer readable storage medium, which stores computer readable program instructions (i.e., a computer program) for executing the test method for improving the estimation accuracy of the state of charge of the power battery, and can solve the technical problem of the complex calculation method and insufficient precision of the state of charge estimation of the power battery management system. Compared with the prior art, the computer readable storage medium provided by the present application has the same beneficial effects as the test method for improving the estimation accuracy of the state of charge of the power battery provided by the above-mentioned embodiments, and will not be described here.

[0226] The present application also provides a computer program product comprising a computer program, which, when executed by a processor, implements the steps of the test method for improving the estimation accuracy of the state of charge of the power battery as described above.

[0227] The computer program product provided in the application can solve the technical problems of complex calculation method and insufficient precision of state of charge estimation of the power battery management system. Compared with the prior art, the beneficial effects of the computer program product provided in the application are the same as those of the test method for improving the state of charge estimation precision of the power battery provided in the above-mentioned embodiments, and will not be repeated here.

[0228] The above is only some embodiments of the application, and does not limit the patent scope of the application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or the like made by using the content of the application specification and drawings within the technical concept of the application is included in the patent protection scope of the application.

Claims

1. A test method for improving the estimation accuracy of the state of charge of a power battery, characterized in that, The application relates to a test system for improving the estimation accuracy of the state of charge of a power battery, and the test system comprises at least a thermostat, a power battery management system and a charging and discharging device. After the temperature of the thermostat is adjusted to room temperature, the power battery is discharged to a first state of charge at a constant current and is charged to a second state of charge at a pulse constant current, so as to complete full discharge and full charge; After the temperature of the thermostat is adjusted to a specific temperature, the power battery is discharged to a third state of charge after being placed. Based on the third state of charge and a fourth state of charge, the power battery is subjected to a charging and discharging cycle test under a preset working condition, and the fourth state of charge is that the SOC is equal to 30%; After the charging and discharging cycle test is completed, the power battery is discharged to the first state of charge, so as to complete full discharge; The charging and discharging current data and charging and discharging time data recorded by the charging and discharging device are obtained, the charging and discharging efficiency is obtained, the first correspondence relationship among the charging and discharging current data, the charging and discharging time data, the charging and discharging efficiency and the battery capacity data is obtained, and the battery capacity data is obtained based on the charging and discharging current data, the charging and discharging time data, the charging and discharging efficiency and the first correspondence relationship; The second correspondence relationship among the battery capacity data, the battery rated capacity and the true value of the state of charge is obtained, and the true value of the state of charge is determined based on the battery capacity data, the battery rated capacity and the second correspondence relationship; The difference between the true value of the state of charge and the state of charge BMS value obtained by the power battery management system is taken as the state of charge absolute error, and the state of charge absolute error comprises the state of charge absolute error of the charging and discharging cycle test and the state of charge absolute error of the overall charging and discharging test; Based on the state of charge absolute error, the state of charge evaluation result is determined, so as to improve the state of charge estimation accuracy of the power battery management system. The first corresponding relationship is The second corresponding relationship is The calculation relationship of the absolute error of the state of charge is The battery capacity data at the time recorded by the charging and discharging device in real time is The charging and discharging current of the power battery is a function of the charging and discharging time, and a positive value indicates charging and a negative value indicates discharging. The initial time is The current time is The true value of the state of charge is The battery capacity data is The rated capacity of the battery is The state of charge BMS value is The charging and discharging efficiency is ​ 2. The method of claim 1, wherein, After the temperature of the thermostat is adjusted to room temperature, the power battery is discharged to a first state of charge at a constant current and is charged to a second state of charge at a pulse constant current, so as to complete full discharge and full charge; After the temperature of the thermostat is adjusted to room temperature, the power battery is discharged to a first state of charge at a constant current and is charged to a second state of charge at a pulse constant current, so as to complete full discharge and full charge; After the temperature of the thermostat is adjusted to a specific temperature, the power battery is discharged to a third state of charge after being placed. After the temperature of the thermostat is adjusted to a specific temperature, the power battery is discharged to a third state of charge after being placed.

3. The method of claim 1, wherein, After the temperature of the thermostat is adjusted to a specific temperature, the power battery is discharged to a third state of charge after being placed. After the temperature of the thermostat is adjusted to a specific temperature, the power battery is discharged to a third state of charge after being placed. ​ 4. The method of claim 1, wherein, ​ In a preset working condition, the power battery is discharged to the fourth state of charge based on a third preset discharge rate, and the power battery is subjected to a standing treatment based on a third standing time; The power battery is charged to the third state of charge based on a fast charging strategy, and the power battery is subjected to a standing treatment based on a fourth standing time; The cycle number is updated, and the above steps are repeatedly executed until the cycle number meets a preset cycle number.

5. The method of claim 1, wherein, The step of discharging the power battery to the first state of charge to complete full discharge after the completion of the charge-discharge cycle test comprises: In a preset working condition, the power battery is discharged to a discharge cutoff voltage based on a fourth preset discharge rate after the completion of the charge-discharge cycle test; After the temperature of the thermostat is adjusted to room temperature, the power battery is subjected to a standing treatment based on a fifth standing time; After the standing is completed, the power battery is discharged to the first state of charge based on a fifth preset discharge rate to complete full discharge.

6. The method of any one of claims 1 to 5, wherein, The step of determining a state of charge evaluation result based on the state of charge absolute error to improve the state of charge estimation accuracy of the power battery management system comprises: When the state of charge absolute error of the charge-discharge cycle test is greater than a preset error threshold, it is determined that the state of charge evaluation result of the charge-discharge cycle test is that the accuracy does not meet the requirements, and the state of charge of the power battery management system is corrected to improve the state of charge estimation accuracy of the power battery management system; When the state of charge absolute error of the charge-discharge overall test is greater than a preset error threshold, it is determined that the state of charge evaluation result of the charge-discharge overall test is that the accuracy does not meet the requirements, and the state of charge of the power battery management system is corrected to improve the state of charge estimation accuracy of the power battery management system.

7. A test device for improving the estimation accuracy of the state of charge of a power battery, characterized in that The device comprises: A test module is configured to discharge the power battery to a first state of charge and pulse constant current charge to a second state of charge to complete full discharge and full charge after the temperature of the thermostat is adjusted to room temperature; The test module is further configured to discharge the power battery to a third state of charge after the temperature of the thermostat is adjusted to a specific temperature; The test module is further configured to perform a charge-discharge cycle test on the power battery in a preset working condition based on the third state of charge and a fourth state of charge, and the fourth state of charge is SOC equal to 30%; The test module is further configured to discharge the power battery to the first state of charge to complete full discharge after the completion of the charge-discharge cycle test; An evaluation module is configured to determine a state of charge absolute error based on a state of charge true value recorded by a charge-discharge device in a charge-discharge test and a state of charge BMS value obtained by a power battery management system; The evaluation module is further configured to determine a state of charge evaluation result based on the state of charge absolute error to improve the state of charge estimation accuracy of the power battery management system; The evaluation module is further configured to determine a state of charge evaluation result based on the state of charge absolute error to improve the state of charge estimation accuracy of the power battery management system; The evaluation module is further configured to obtain the charging and discharging current data and the charging and discharging time data recorded by the charging and discharging device, obtain the charging and discharging efficiency, obtain a first correspondence relationship among the charging and discharging current data, the charging and discharging time data, the charging and discharging efficiency and the battery capacity data, and obtain the battery capacity data based on the charging and discharging current data, the charging and discharging time data, the charging and discharging efficiency and the first correspondence relationship; obtain a second correspondence relationship among the battery capacity data, the battery rated capacity and the true value of the state of charge, and determine the true value of the state of charge based on the battery capacity data, the battery rated capacity and the second correspondence relationship; obtain the state of charge BMS value obtained by the power battery management system, and take a difference between the true value of the state of charge and the state of charge BMS value as the absolute error of the state of charge, the absolute error of the state of charge including the absolute error of the state of charge in the charging and discharging cycle test and the absolute error of the state of charge in the overall charging and discharging test; The first correspondence is The second correspondence is The formula for calculating the absolute error of the state of charge is: Real-time recording for charging and discharging equipment Battery capacity data at any given time. The charging and discharging current of the power battery is a function of the charging and discharging time; a positive value indicates charging, and a negative value indicates discharging. At the initial moment, For the current moment, This represents the true value of the state of charge. For battery capacity data, For the battery's rated capacity, This is the BMS value for the state of charge. This refers to the charge / discharge efficiency.

8. A test device for improving the estimation accuracy of the state of charge of a power battery, characterized by The device comprises a memory, a processor and a computer program stored on the memory and executable on the processor, and the computer program is configured to implement the steps of the test method for improving the estimation accuracy of the state of charge of a power battery according to any one of claims 1 to 6.

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