Power battery charge state estimation method, battery management equipment and hybrid electric vehicle

Abstract

The invention discloses a power battery charge state estimation method, battery management equipment and a hybrid electric vehicle, and relates to the technical field of automobiles. According to the power battery state-of-charge estimation method, a charging platform area of a power battery in a target hybrid vehicle is obtained, multiple states of charge in the charging platform area are determined as charging targets based on the charging platform area, a charging test is carried out on the power battery, and a charging relation curve of the power battery for the multiple states of charge under each preset working condition is obtained; when the charge state of the power battery is estimated, the current charging voltage and the current charging capacity of the power battery are obtained, and then the current charge state is calibrated by adopting the charging relation curve of the power battery for multiple charge states under multiple preset working conditions, so that the target charge state of the power battery is obtained; therefore, the problem of inaccurate estimation in the platform area range of the OCV-SOC curve when the SOC of the power battery is estimated by using the OCV-SOC curve is avoided, and the SOC estimation accuracy of the power battery is improved.

Description

Technical Field

[0001] The present invention relates to the field of automobile technology, and in particular to a power battery state of charge estimation method, a battery management device and a hybrid vehicle. Background Art

[0002] The state of charge (SOC) of a battery refers to the ratio of the remaining power of the battery to the total capacity, usually expressed as a percentage. SOC estimation plays a vital role in the battery management system (BMS), and its accuracy directly affects the battery's efficiency, safety, life, and the mileage and performance of electric vehicles.

[0003] The current power battery SOC estimation is mainly achieved based on an OCV-SOC (Open Circuit Voltage to State of Charge) curve formed by the relationship between the open circuit voltage and SOC of the power battery.

[0004] However, the OCV-SOC curve of some power batteries is relatively flat in the middle part, which cannot well reflect the relationship between its open circuit voltage and SOC, resulting in insufficient accuracy in power battery SOC estimation. Summary of the invention

[0005] The main purpose of the present invention is to propose a method for estimating the state of charge of a power battery, a battery management device and a hybrid vehicle, aiming to improve the accuracy of power battery SOC estimation.

[0006] In a first aspect, the present invention provides a method for estimating a state of charge of a power battery, comprising:

[0007] Obtain the charging platform area of ​​the power battery in the target hybrid vehicle;

[0008] Taking multiple charge states in the charging platform area as charging targets, controlling the engine in the target hybrid vehicle to generate pulse current under multiple preset working conditions, performing a charging test on the power battery, and obtaining a charging relationship curve of the power battery for the multiple charge states under each preset working condition, wherein the charging relationship curve of each charge state is used to characterize a relationship curve of voltage and capacity changes during the charging process taking each charge state as the charging target;

[0009] Obtaining the current charging voltage and current charging capacity of the power battery;

[0010] According to the current charging voltage, the current state of charge is calibrated using the charging relationship curves of the power battery for the multiple states of charge under the multiple preset working conditions to obtain a target state of charge of the power battery.

[0011] In an optional implementation manner, obtaining the charging platform area of ​​the power battery in the target hybrid vehicle includes:

[0012] Obtaining a preset relationship curve between the open circuit voltage and the state of charge of the power battery;

[0013] Performing a derivation operation on the preset relationship curve to obtain a charge voltage change rate curve of the power battery, wherein the charge voltage change rate curve is used to characterize a change rate of the preset relationship curve;

[0014] According to the charge change rate curve, a charge state interval in which the charge voltage change rate is less than or equal to a first preset charge voltage change rate threshold is determined as the charging platform area.

[0015] In an optional embodiment, the method of taking multiple charge states in the charging platform area as charging targets, controlling the engine in the target hybrid vehicle to generate pulse current under multiple preset working conditions, performing a charging test on the power battery, and obtaining a charging relationship curve of the power battery for the multiple charge states under each preset working condition includes:

[0016] Under each of the preset operating conditions, the ambient temperature of the power battery is adjusted to a target temperature within a preset temperature range;

[0017] Under each of the preset working conditions, controlling the engine to generate and output a preset standard pulse current to charge the power battery to each state of charge;

[0018] Under each of the preset operating conditions, at a rate in a preset rate range, the engine is controlled to generate and output a pulse current corresponding to the rate, and the power battery is continuously charged for a first preset time period;

[0019] According to the electrical parameters of the power battery when charged to each state of charge, a charging relationship curve of the power battery for each state of charge under each preset working condition is drawn.

[0020] In an optional embodiment, under each of the preset operating conditions, before controlling the engine to generate and output a preset standard pulse current and charging the power battery to each state of charge, the method further includes:

[0021] Under each of the preset operating conditions, the power battery is discharged to a preset cut-off voltage at a preset standard discharge rate and left to stand for a second preset time period.

[0022] In an optional embodiment, under each of the preset operating conditions, at a rate in a preset rate range, the engine is controlled to generate and output a pulse current corresponding to the rate, and before the power battery continues to be charged for a first preset time, the method further includes:

[0023] After the power battery is charged to each state of charge, standing for a third preset time;

[0024] After continuing to charge the power battery for a first preset time period, the method further includes:

[0025] Let stand for a fourth preset time period.

[0026] In an optional embodiment, the step of calibrating the current state of charge according to the current charging voltage and using the charging relationship curves of the power battery for the multiple states of charge under the multiple preset working conditions to obtain the target state of charge of the power battery includes:

[0027] Performing polynomial fitting on the charging relationship curves of the power battery for the multiple states of charge under the multiple preset operating conditions to obtain a fitting coefficient matrix corresponding to the power battery;

[0028] Calculating a current charging voltage change rate according to the current charging voltage and the current charging capacity;

[0029] Calculating a charge voltage variation matrix according to the current charge voltage and the fitting coefficient matrix;

[0030] Determining an error matrix according to the current charge voltage change rate and the charge voltage change matrix;

[0031] The target state of charge is determined according to the error matrix.

[0032] In an optional embodiment, before performing polynomial fitting on the charging relationship curves of the power battery for the multiple states of charge under the multiple preset operating conditions to obtain a fitting coefficient matrix corresponding to the power battery, the method further includes:

[0033] According to the preset window size, a moving average smoothing method is adopted to smooth the charging relationship curves of the power battery for the multiple charge states under the multiple preset working conditions. The preset window size is used to characterize the number of sampling points in a single window during the moving process.

[0034] In an optional implementation manner, determining the target state of charge according to the error matrix includes:

[0035] Determining a minimum element in the error matrix;

[0036] If the charge voltage change rate of the minimum element is less than a second preset charge voltage change rate threshold, the charge state corresponding to the minimum element is determined to be the target charge state.

[0037] In a second aspect, the present invention provides a battery management device, comprising: a processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, the processor and the storage medium communicate via the bus, and the processor executes the machine-readable instructions to perform a method as described in any of the aforementioned embodiments.

[0038] In a third aspect, the present invention provides a hybrid vehicle, comprising: a power battery, an engine and a battery management device as described in the aforementioned embodiments, wherein the power battery and the engine are electrically connected, and the battery management device is also communicatively connected between the power battery and the engine, and the battery management device is used to execute the method as described in any of the aforementioned embodiments.

[0039] The beneficial effects of the present invention are:

[0040] A method for estimating the state of charge of a power battery provided in an embodiment of the present invention comprises: obtaining a charging platform area of ​​a power battery in a target hybrid vehicle; taking multiple states of charge in the charging platform area as charging targets, controlling an engine in the target hybrid vehicle to generate a pulse current under multiple preset operating conditions, performing a charging test on the power battery, and obtaining a charging relationship curve of the power battery for the multiple states of charge under each preset operating condition, wherein the charging relationship curve of each state of charge is used to characterize a relationship curve of voltage and capacity changes during a charging process with each state of charge as a charging target; obtaining a current charging voltage and a current charging capacity of the power battery; and according to the current charging voltage, using the charging relationship curve of the power battery for the multiple states of charge under the multiple preset operating conditions, calibrating the current state of charge to obtain a target state of charge of the power battery. In this embodiment, by obtaining the charging platform area of ​​the power battery in the target hybrid vehicle, and based on this, determining multiple charge states in the charging platform area as charging targets, and then performing a charging test on the power battery, a charging relationship curve of the power battery for multiple charge states under each preset working condition is obtained, and when estimating the power battery charge state, the charging relationship curves of the power battery for multiple charge states under multiple preset working conditions are used to calibrate the current charge state to obtain the target charge state of the power battery, thereby avoiding the problem of inaccurate estimation within the platform area of ​​the OCV-SOC curve when estimating the power battery SOC using the OCV-SOC curve, and improving the accuracy of the power battery SOC estimation. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0042] Figure 1 A schematic diagram of a flow chart of a method for estimating the state of charge of a power battery provided in an embodiment of the present application;

[0043] Figure 2 A schematic diagram of the charging relationship curve of the power battery of this application;

[0044] Figure 3 A schematic diagram of a flow chart of a method for estimating the state of charge of a power battery provided in another embodiment of the present application;

[0045] Figure 4 A schematic diagram of a preset relationship curve between the open circuit voltage and the state of charge of the power battery of the present application;

[0046] Figure 5 A schematic diagram of a charge voltage change rate curve of the power battery of the present application;

[0047] Figure 6 A schematic diagram of a flow chart of a method for estimating the state of charge of a power battery provided in another embodiment of the present application;

[0048] Figure 7 A schematic diagram of a flow chart of a method for estimating the state of charge of a power battery provided in yet another embodiment of the present application;

[0049] Figure 8 A schematic diagram of the structure of a power battery state of charge estimation device provided by an embodiment of the present invention;

[0050] Fig. 9 A schematic structural diagram of a battery management device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0052] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0053] It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures. The terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device that includes a series of elements includes not only those elements, but also includes other elements that are not explicitly listed, or also includes elements that are inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the statement "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device that includes the element.

[0054] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0055] The current power battery SOC estimation method usually directly obtains the current open circuit voltage of the power battery, and reads the current theoretical SOC value of the power battery as the estimation result on the OCV-SOC curve formed by the relationship between the open circuit voltage and SOC of the power battery. However, since the OCV-SOC curve of some power batteries is relatively flat in the middle part, the SOC change is not obvious when the open circuit voltage changes. Therefore, when the current power battery SOC estimation method is used for SOC estimation of this part of the power battery, it cannot achieve accurate estimation in the flat range of the OCV-SOC curve. The present invention aims to propose a power battery state of charge estimation method, which can improve the accuracy of power battery SOC estimation.

[0056] Figure 1 This is a flow chart of a method for estimating the state of charge of a power battery provided in an embodiment of the present application. The execution subject of the method may be an electronic terminal such as a computer, such as Figure 1 As shown, the method includes:

[0057] S101. Obtain a charging platform area of ​​a power battery in a target hybrid vehicle.

[0058] Among them, the above-mentioned charging platform area may refer to a relatively flat part of the OCV-SOC curve formed by the relationship between the open circuit voltage and SOC of the power battery. Of course, the specific standard for defining the relatively flat part of the above-mentioned OCV-SOC curve can be determined according to actual needs and is not limited here. It can be understood that in the same OCV-SOC curve, there may be only one or more charging platform areas.

[0059] Since the relatively flat portion of the above-mentioned OCV-SOC curve cannot well reflect the relationship between the open circuit voltage and SOC of the power battery, the purpose of obtaining the above-mentioned charging platform area can be to clarify the SOC range that needs to be calibrated, and the portion of the OCV-SOC curve outside the above-mentioned charging platform area can more accurately reflect the relationship between the open circuit voltage and SOC of the power battery, and then be directly used for power battery SOC estimation without calibration.

[0060] S102, taking the multiple charge states in the above-mentioned charging platform area as charging targets, controlling the engine in the above-mentioned target hybrid vehicle to generate pulse current under multiple preset operating conditions, and performing a charging test on the above-mentioned power battery to obtain a charging relationship curve of the above-mentioned power battery for the above-mentioned multiple charge states under each preset operating condition, wherein the charging relationship curve of each charge state is used to characterize the relationship curve of the voltage and capacity changes during the charging process with the above-mentioned each charge state as the charging target.

[0061] Among them, the multiple states of charge in the above-mentioned charging platform area can be selected at certain intervals or rules within the state of charge range corresponding to the above-mentioned charging platform area. Exemplarily, the above-mentioned interval can be 1SOC-5SOC. Assuming that there is only one above-mentioned charging platform area, and the state of charge range corresponding to the charging platform area is 30SOC-50SOC, then the multiple states of charge in the above-mentioned charging platform area can be, for example, 30SOC, 35SOC, 40SOC, 45SOC and 50SOC. Of course, the content here is only an example. How to select the multiple states of charge in the specific charging platform area can be determined according to actual needs and is not limited here.

[0062] The above-mentioned preset working conditions can be determined by test parameters such as temperature and pulse current value. The range of the above-mentioned temperature and pulse current value is related to the inherent characteristics of the power battery and can be determined according to the actual situation of the power battery. For example, assuming that the operating temperature range of a power battery is -30℃~55℃, then the range of the above-mentioned temperature can be -30℃~55℃, then the temperature selected within the temperature range can be, for example, -20℃, 25℃, 45℃; assuming that the pulse current range that the power battery can withstand is 0.5C-3C, then the range of the above-mentioned pulse current value can be 0.5C-3C, then in the pulse current The pulse current value selected within the numerical range can be, for example, 0.5C, 1C, 2C, and 3C, that is, by selecting different temperatures and pulse current values ​​within the above-mentioned temperature and pulse current value ranges, a plurality of different preset operating conditions can be determined. It can be understood that the specific number of test parameters used to determine the preset operating conditions can be determined according to actual needs and is not limited to the above examples. Of course, under normal circumstances, the more test parameters there are and the more values ​​selected within the range of each test parameter, the more preset operating conditions will be determined by their combination (that is, the higher the experimental complexity), and the corresponding test data may be more accurate.

[0063] The charging relationship curve of the power battery for the above-mentioned multiple charge states under each of the above-mentioned preset working conditions may refer to the following: Figure 2 The IC curve (Incremental Capacity Curve) of the power battery is shown, wherein the horizontal axis of the IC curve represents the charging voltage V of the power battery, and the vertical axis represents the differential ratio dQ / dV of the charging capacity Q of the power battery to the charging voltage V. The parameters such as the charging voltage V and the charging capacity Q of the power battery can be collected or calculated during the test.

[0064] S103: Obtain the current charging voltage and current charging capacity of the power battery.

[0065] When estimating the actual SOC of the power battery, the charging voltage under the current actual working condition, that is, the above-mentioned current charging voltage, is obtained. Specifically, the current charging voltage of the power battery can be obtained by a sensor, etc., but is not limited to this. For example, the current charging capacity of the power battery can be obtained by collecting the current charging current and the current charging time and then calculating according to the formula q=it, wherein q is the above-mentioned current charging capacity, i is the above-mentioned current charging current, and t is the above-mentioned current charging time. Of course, the specific method of obtaining the current charging capacity of the power battery can be selected and determined according to the actual situation, and is not limited here.

[0066] Similar to the principles of the above content, the current discharge voltage and current discharge capacity of the above power battery can also be obtained. However, when estimating the actual power battery SOC, charging can be completed at any time by relying on the hybrid vehicle generator, while discharging usually requires the driver to step on the accelerator pedal to complete. Therefore, it is easier to collect the current charging voltage and current charging capacity. However, whether to obtain the voltage and capacity through charging, discharging or other methods can be determined according to actual conditions and is not limited to the above content.

[0067] S104 , according to the current charging voltage, using the charging relationship curves of the power battery for the multiple states of charge under the multiple preset working conditions, calibrate the current state of charge to obtain a target state of charge of the power battery.

[0068] Firstly, the charging relationship curve of the power battery for the above-mentioned multiple states of charge under the same working condition as the current actual working condition can be selected from the charging relationship curves of the above-mentioned power battery for the above-mentioned multiple states of charge under the above-mentioned multiple preset working conditions. It can be understood that the above-mentioned multiple preset working conditions obviously cannot guarantee to include any current actual working condition. Therefore, when there is no working condition that is completely consistent with the current actual working condition among the above-mentioned multiple preset working conditions, the charging relationship curve of the above-mentioned power battery for the above-mentioned multiple states of charge under the preset working condition closest to the current actual working condition can be used to calibrate the above-mentioned current state of charge to obtain the target state of charge of the above-mentioned power battery. The specific method of judging the closest preset working condition may be, for example, the temperature being closest, the pulse current value being closest, or the temperature and pulse current being closest in comprehensive calculation, etc. The specific judgment method is not limited here.

[0069] Exemplarily, the above-mentioned calibration of the current state of charge to obtain the target state of charge of the power battery can be specifically to bring the current charging voltage as an input value into the charging relationship curves of the power battery under the same or closest working conditions for the above-mentioned multiple states of charge, and obtain the differential ratio dQ / dV of the charging capacity Q of the power battery corresponding to each charging relationship curve to the charging voltage V (i.e., the above-mentioned Figure 2 The value of the vertical axis in the middle), and then according to the current charging voltage v and the current charging capacity q of the above-mentioned power battery, the differential ratio dq / dv of the current charging capacity v and the current charging voltage q is calculated, and the dq / dv is compared with the multiple dQ / dV corresponding to the above-mentioned multiple charging relationship curves, and the charge state of the charging relationship curve corresponding to the dQ / dV closest to dq / dv (that is, the absolute value of the difference between the two is the smallest) is selected as the corrected power battery charge state estimation result, that is, the target charge state of the above-mentioned power battery.

[0070] In an embodiment of the present invention, a charging platform area of ​​a power battery in a target hybrid vehicle is obtained; with multiple charge states in the charging platform area as charging targets, an engine in the target hybrid vehicle is controlled to generate a pulse current under multiple preset operating conditions, a charging test is performed on the power battery, and a charging relationship curve of the power battery for the multiple charge states under each preset operating condition is obtained, wherein the charging relationship curve of each charge state is used to characterize a relationship curve of voltage and capacity changes during a charging process with each charge state as a charging target; a current charging voltage and a current charging capacity of the power battery are obtained; and according to the current charging voltage, the current charge state is calibrated using the charging relationship curve of the power battery for the multiple charge states under the multiple preset operating conditions to obtain a target charge state of the power battery. In this embodiment, by obtaining the charging platform area of ​​the power battery in the target hybrid vehicle, and based on this, determining multiple charge states in the charging platform area as charging targets, and then performing a charging test on the power battery, a charging relationship curve of the power battery for multiple charge states under each preset working condition is obtained, and when estimating the charge state of the power battery, the charging relationship curve of the power battery for multiple charge states under multiple preset working conditions is used to calibrate the current charge state to obtain the target charge state of the power battery, thereby avoiding the problem of inaccurate estimation within the OCV-SOC curve platform area when estimating the power battery SOC using the OCV-SOC curve, and improving the accuracy of the power battery SOC estimation. .

[0071] Figure 3 A schematic flow chart of a method for estimating the state of charge of a power battery provided in another embodiment of the present application is shown in FIG. Figure 3 As shown, in Figure 1 Based on the embodiment, the above-mentioned acquisition of the charging platform area of ​​the power battery in the target hybrid vehicle may include:

[0072] S301, obtaining a preset relationship curve between the open circuit voltage and the state of charge of the power battery.

[0073] The preset relationship curve between the open circuit voltage and the state of charge of the power battery is the above-mentioned OCV-SOC curve. The preset relationship curve between the open circuit voltage and the state of charge of the power battery can be as follows: Figure 4 As shown, the horizontal axis of the preset relationship curve between the open circuit voltage and the state of charge of the power battery represents the state of charge SOC of the power battery, and the vertical axis represents the open circuit voltage OCV of the power battery. Of course, the specific preset relationship curve style between the open circuit voltage and the state of charge of the power battery is not limited to Figure 4 It can be determined according to actual needs.

[0074] S302 , performing a derivative operation on the preset relationship curve to obtain a charge voltage change rate curve of the power battery, wherein the charge voltage change rate curve is used to characterize a change rate of the preset relationship curve.

[0075] Among them, after the above preset relationship curve is derived, the following can be obtained: Figure 5 The dOCV / dSOC-SOC curve shown is the charge voltage change rate curve of the power battery. Of course, the specific charge voltage change rate curve of the power battery is not limited to Figure 5 It can be determined according to actual needs.

[0076] S303 , according to the charge change rate curve, determining a charge state interval in which a charge voltage change rate is less than or equal to a first preset charge voltage change rate threshold as the charging platform area.

[0077] Please continue to refer to Figure 5 , the first preset charge voltage change rate threshold can be Figure 5 K1 in Figure 5 It can be obtained that the intervals corresponding to the above 30SOC-50.4SOC and 64SOC-90SOC are the above charging platform areas. Of course, how to determine the first preset charge voltage change rate threshold and the charging platform area is not limited to the generated curve, and can also be better displayed in a table or other graphical form, and is not limited to the above combination. Figure 5 The examples are limited.

[0078] In this embodiment, a preset relationship curve between the open circuit voltage and the state of charge of the power battery is obtained; the preset relationship curve is derivatized to obtain the charge voltage change rate curve of the power battery, and the charge voltage change rate curve is used to characterize the change rate of the preset relationship curve; according to the charge change rate curve, the state of charge interval in which the charge voltage change rate is less than or equal to the first preset charge voltage change rate threshold is determined as the charging platform area. By derivating the preset relationship curve to obtain the charge voltage change rate curve of the power battery, the charging platform area is determined by the first preset charge voltage change rate threshold, thereby improving the standardization and accuracy of the acquisition of the charging platform area, and providing support for subsequent targeted experiments on the charging platform area.

[0079] Figure 6 A schematic flow chart of a method for estimating the state of charge of a power battery provided in another embodiment of the present application is shown in FIG. Figure 6 As shown, in Figure 1Based on the embodiment, the above-mentioned multiple charge states in the above-mentioned charging platform area are used as charging targets, the engine in the above-mentioned target hybrid vehicle is controlled to generate pulse current under multiple preset working conditions, and the above-mentioned power battery is charged. The charging relationship curve of the above-mentioned power battery for the above-mentioned multiple charge states under each preset working condition can include:

[0080] S601. Under each of the above preset working conditions, the ambient temperature of the power battery is adjusted to a target temperature in a preset temperature range.

[0081] The above-mentioned adjustment of the ambient temperature of the power battery to a target temperature in a preset temperature range can be achieved in a box with a temperature control function, and the power battery can be placed in the box with a temperature control function. However, the above content is only an example, and the actual implementation method is not limited to this.

[0082] The determination of the above-mentioned preset temperature range is affected by the operating temperature range of the power battery. For example, assuming that the operating temperature range of a power battery is -30℃~55℃, then the above-mentioned preset temperature range can be -30℃~55℃. Then the above-mentioned target temperature selected within the temperature range can be, for example, -20℃, 25℃, 45℃, etc., but is not limited to this.

[0083] S602. Under each of the above preset operating conditions, control the above engine to generate and output a preset standard pulse current to charge the above power battery to each charge state.

[0084] The determination of the above-mentioned preset standard pulse current is affected by the pulse current range that the power battery can withstand. For example, assuming that the pulse current range that a power battery can withstand is 0.5C-3C, then the above-mentioned preset standard pulse current can be, for example, 0.5C, 1C, 2C, 3C, etc., but not limited to this.

[0085] Before charging the above-mentioned power battery to each state of charge, the power battery can be discharged to the cut-off voltage of the power battery according to a preset standard pulse current and then charging can be started. When charging the above-mentioned power battery to each state of charge, it can be charged to each state of charge in sequence, for example, charged to 30SOC, then charged to 35SOC, and then charged to 40SOC... or each time it is charged to a charge state, it is discharged to the cut-off voltage of the power battery according to the preset standard pulse current again, and then charged to the next charge state. The specific charging method can be selected and determined according to actual needs and is not limited here.

[0086] S603. Under each of the above preset operating conditions, at a rate in a preset rate range, control the above engine to generate and output a pulse current corresponding to the above rate, and continue to charge the above power battery for a first preset time period.

[0087] The determination of the above-mentioned preset rate range is also affected by the pulse current range that the power battery can withstand. For example, assuming that the pulse current range that a power battery can withstand is 0.5C-3C, then the above-mentioned preset rate range can be 0.5C-3C, and the pulse current corresponding to the above-mentioned rate that controls the above-mentioned engine to generate and output can be, for example, 0.5C, 1C, 2C, 3C, etc. The above-mentioned first preset time length can be selected and determined within the range of 1s-30s, for example. Of course, the above content is for illustration only and is not limited to this.

[0088] S604: drawing a charging relationship curve of the power battery for each state of charge under each preset working condition according to the electrical parameters of the power battery when charged to each state of charge.

[0089] The electrical parameters of the power battery may include the charging voltage V, the charging current I, and the current charging time T of the power battery, and the charging capacity Q of the power battery may be calculated by the formula Q=IT. Drawing the charging relationship curve of the power battery for each of the above-mentioned charge states under each of the above-mentioned preset working conditions may refer to drawing the following: Figure 2 The IC curve of the power battery shown in FIG. 1 is a graph showing the IC curve of the power battery, wherein the horizontal axis of the IC curve represents the charging voltage V of the power battery, and the vertical axis represents the differential ratio dQ / dV of the charging capacity Q of the power battery to the charging voltage V. The definition and adjustment method of each of the above-mentioned preset working conditions and each state of charge can be referred to the above in step S102, and will not be repeated here. Of course, the above contents are all examples, and are not limited thereto.

[0090] In this embodiment, under each of the above preset working conditions, the ambient temperature of the power battery is adjusted to a target temperature in the preset temperature range; under each of the above preset working conditions, the engine is controlled to generate and output a preset standard pulse current to charge the power battery to each state of charge; under each of the above preset working conditions, the engine is controlled to generate and output a pulse current corresponding to the above rate at a rate in the preset rate range to continue charging the power battery for the first preset time; and according to the electrical parameters of the power battery charged to each of the above states of charge, the charging relationship curve of the power battery for each of the above states of charge under each of the above preset working conditions is drawn. By adjusting the target temperature and the preset standard pulse current, different preset working conditions are constructed, and the drawing of the charging relationship curve of the power battery for each of the above states of charge under each preset working condition is realized, thereby providing necessary data for estimating the state of charge of the power battery using the charging relationship curve.

[0091] In addition, based on the above embodiment, under each of the above preset working conditions, the engine is controlled to generate and output a preset standard pulse current, and before the power battery is charged to each state of charge, the method may further include:

[0092] Under each of the above preset working conditions, the above power battery is discharged to a preset cut-off voltage at a preset standard discharge rate and left to stand for a second preset time period.

[0093] The purpose of doing so may be to restore stability to the power battery after discharge, thereby reducing measurement errors in subsequent work, etc. The above-mentioned second preset time length can be selected and determined within the range of 10min-60min, for example, it can be 20min, 30min, 40min, etc., but is not limited to this.

[0094] Further, in Figure 6 Based on the embodiment, under each of the above preset working conditions, at a rate in a preset rate range, the engine is controlled to generate and output a pulse current corresponding to the above rate, and before continuing to charge the power battery for a first preset time, the method may further include: after the power battery is charged to each of the above charge states, standing for a third preset time;

[0095] After continuing to charge the power battery for the first preset time period, the method further includes: standing for a fourth preset time period.

[0096] The purpose of doing so may also be to restore the stability of the power battery, thereby reducing measurement errors in subsequent work, etc. The third preset time length and the fourth preset time length may also be selected and determined within the range of 10min-60min, for example, 20min, 30min, 40min, etc., but not limited to this.

[0097] Figure 7 A schematic flow chart of a method for estimating the state of charge of a power battery provided in yet another embodiment of the present application is shown in FIG. Figure 7 As shown, in Figure 1 On the basis of the embodiment, the current state of charge is calibrated according to the current charging voltage by using the charging relationship curves of the power battery for the multiple states of charge under the multiple preset working conditions to obtain the target state of charge of the power battery, which may include:

[0098] S701, performing polynomial fitting on the charging relationship curves of the power battery for the multiple charge states under the multiple preset working conditions to obtain a fitting coefficient matrix corresponding to the power battery.

[0099] For example, if the charging voltage V is x, the differential ratio dQ / dV of the charging capacity Q and the charging voltage V is p, and the highest term of the polynomial coefficient is n, then the formula can be obtained based on the least squares method:

[0100] p(x)=p1xn+p2xn-1+...+pnx+pn+1

[0101] Since the power battery has a charging relationship curve for each charge state under each working condition, and each charging relationship curve corresponds to the above formula, taking the highest term n=5 of the above polynomial coefficient as an example, the power battery under a certain working condition is subjected to polynomial fitting for the charging relationship curves of the above multiple charge states, and the fitting coefficient matrix corresponding to the above power battery can be shown in the following Table 1:

[0102]

[0103] Table 1

[0104] Among them, m in Table 1 above represents the number of charge states, and the subscript of P is only used as a matrix position number and has no practical meaning. It can be understood that since there are multiple preset operating conditions, there can also be multiple fitting coefficient matrices shown in Table 1 above. Of course, the actual way to represent the above fitting coefficient matrix can be selected and determined according to actual conditions and is not limited to the form of Table 1 above.

[0105] S702: Calculate the current charging voltage change rate according to the current charging voltage and the current charging capacity.

[0106] The current charge voltage change rate may be the differential ratio dq / dv of the current charge capacity v and the current charge voltage q. The specific calculation process may refer to the above step S104 and will not be repeated here.

[0107] S703: Calculate a charge voltage variation matrix according to the current charge voltage and the fitting coefficient matrix.

[0108] The above-mentioned calculated charge voltage change matrix is ​​to take the above-mentioned current charge capacity v as the input value into the above-mentioned fitting coefficient matrix under the desired working condition or the closest working condition, so as to obtain the differential ratio dQ / dV of multiple power battery charge capacity Q and charge voltage V and record it in matrix form, that is, the above-mentioned charge voltage change matrix.

[0109] S704: Determine an error matrix according to the current charge voltage change rate and the charge voltage change matrix.

[0110] The differential ratio dq / dv of the current charging capacity v and the current charging voltage q is subtracted from the differential ratio dQ / dV of the charging capacity Q and the charging voltage V of multiple power batteries in the charging voltage change matrix, and the absolute value of the difference is recorded in a matrix form, namely the error matrix.

[0111] S705: Determine the target state of charge according to the error matrix.

[0112] The charge state of the charging relationship curve corresponding to the differential ratio dQ / dV of the power battery charging capacity Q to the charging voltage V corresponding to the minimum value in the error matrix is ​​selected as the corrected power battery charge state estimation result, that is, the above-mentioned target charge state.

[0113] In an embodiment of the present invention, a fitting coefficient matrix corresponding to the power battery is obtained by performing polynomial fitting on the charging relationship curves of the power battery for the multiple charge states under the multiple preset operating conditions; the current charge voltage change rate is calculated according to the current charging voltage and the current charging capacity; the charge voltage change matrix is ​​calculated according to the current charging voltage and the fitting coefficient matrix; the error matrix is ​​determined according to the current charge voltage change rate and the charge voltage change matrix; and the target charge state is determined according to the error matrix. By bringing the current charging voltage as an input value into the fitting coefficient matrix, a charging voltage change matrix is ​​obtained, and then the current charging voltage change rate is subtracted from the values ​​in the above charging voltage change matrix to form an error matrix, and then the charge state of the charging relationship curve corresponding to the differential ratio dQ / dV of the power battery charging capacity Q and the charging voltage V corresponding to the minimum value in the error matrix is ​​found, so that the charge state closest to the current charge state is found based on the fitting coefficient matrix, and the above target charge state is determined using the charge state closest to the current charge state, avoiding the problem of inaccurate estimation within the platform area of ​​the OCV-SOC curve when using the OCV-SOC curve to estimate the power battery SOC, and improving the accuracy of the power battery charge state estimation.

[0114] In addition, based on the above embodiment, before performing polynomial fitting on the charging relationship curves of the power battery for the above multiple states of charge under the above multiple preset working conditions to obtain a fitting coefficient matrix corresponding to the above power battery, the method may further include:

[0115] According to the preset window size, a moving average smoothing method is adopted to smooth the charging relationship curves of the power battery for the above-mentioned multiple charge states under the above-mentioned multiple preset working conditions. The above-mentioned preset window size is used to characterize the number of sampling points in a single window during the moving process.

[0116] The principle of the above method can be to correct a certain point in the above charging relationship curve by the average value of several points adjacent to the point and the point. For example, assuming that the above preset window size is 5, it means that the average value of a total of 4 points adjacent to the point on both sides plus the point itself is used as the smoothed value of the point. Since there is no adjacent point on one side of the initial and last points, they cannot be corrected by the above method, and only the value of the point itself can be used directly as the smoothed value. The second point and the second to last point have less than 2 points on one side, so only 1 point can be taken on each side, and 3 is used as the preset window size for sampling. In this way, there is a formula:

[0117] yy(1)=y(1)

[0118] yy(2)=(y(1)+y(2)+y(3)) / 3

[0119] yy(3)=(y(1)+y(2)+y(3)+y(4)+y(5)) / 5

[0120] …

[0121] yy(n)=(y(n-2)+y(n-1)+y(n)+y(n+1)+y(n+2)) / 5

[0122] Among them, the above yy(1)-yy(n) is the value after the above smoothing processing, and y(1)-y(n+2) is the value of the sampling point. It can be understood that as the preset window size changes, the sampling point of the above formula may be different, and the corresponding divisor may also be different, and no specific limitation is made here.

[0123] Further, in Figure 7 Based on the embodiment, determining the target state of charge according to the error matrix may include:

[0124] Determine the minimum element in the above error matrix;

[0125] If the charge voltage change rate of the minimum element is less than the second preset charge voltage change rate threshold, the charge state corresponding to the minimum element is determined to be the target charge state.

[0126] The minimum element in the above error matrix is ​​the minimum value in the above error matrix. The second preset charge voltage change rate threshold is set to ensure that the charge state of the charging relationship curve corresponding to the differential ratio dQ / dV of the power battery charging capacity Q and the charging voltage V corresponding to the selected minimum value in the error matrix is ​​small when used as the current charge state, so as to ensure the accuracy of the above target charge state. The specific setting of the second preset charge voltage change rate threshold can be determined according to actual conditions and is not limited here.

[0127] Figure 8 The present invention provides a schematic diagram of the structure of a power battery state of charge estimation device provided in an embodiment of the present invention. The power battery state of charge estimation device can execute the power battery state of charge estimation method described above. The device can be integrated into an electronic terminal such as a computer, such as Figure 8 As shown, the device comprises:

[0128] The acquisition module 810 is used to acquire the charging platform area of ​​the power battery in the target hybrid vehicle; and acquire the current charging voltage and current charging capacity of the power battery.

[0129] The test module 820 is used to control the engine in the target hybrid vehicle to generate pulse current under multiple preset operating conditions with multiple charge states in the above-mentioned charging platform area as charging targets, and to perform a charging test on the above-mentioned power battery to obtain a charging relationship curve of the above-mentioned power battery for the above-mentioned multiple charge states under each preset operating condition, wherein the charging relationship curve of each charge state is used to characterize the relationship curve of the voltage and capacity changes during the charging process with each charge state as the charging target.

[0130] The calibration module 830 is used to calibrate the current state of charge according to the current charging voltage and the charging relationship curves of the power battery for the multiple states of charge under the multiple preset working conditions to obtain a target state of charge of the power battery.

[0131] In the embodiment of the present invention, by obtaining the charging platform area of ​​the power battery in the target hybrid vehicle, and based on this, determining multiple charge states in the charging platform area as charging targets, and then performing a charging test on the power battery, a charging relationship curve of the power battery for multiple charge states under each preset working condition is obtained, and when estimating the charge state of the power battery, the charging relationship curves of the power battery for multiple charge states under multiple preset working conditions are used to calibrate the current charge state and obtain the target charge state of the power battery, thereby avoiding the problem of inaccurate estimation within the platform area of ​​the OCV-SOC curve when estimating the SOC of the power battery using the OCV-SOC curve, and improving the accuracy of the power battery SOC estimation.

[0132] Optionally, the acquisition module 810 is specifically used to acquire a preset relationship curve between the open circuit voltage and the state of charge of the power battery; perform a derivative operation on the preset relationship curve to obtain a charge voltage change rate curve of the power battery, wherein the charge voltage change rate curve is used to characterize the rate of change of the preset relationship curve; and determine, based on the charge change rate curve, a charge state interval in which the charge voltage change rate is less than or equal to a first preset charge voltage change rate threshold as the charging platform area.

[0133] Optionally, the test module 820 is specifically used to adjust the ambient temperature of the power battery to a target temperature in a preset temperature range under each of the preset operating conditions; to control the engine to generate and output a preset standard pulse current to charge the power battery to each state of charge under each of the preset operating conditions; to control the engine to generate and output a pulse current corresponding to a rate in a preset rate range to continue charging the power battery for a first preset time under each of the preset operating conditions; and to draw a charging relationship curve of the power battery for each state of charge under each of the preset operating conditions according to the electrical parameters of the power battery when charged to each of the charge states.

[0134] Optionally, the test module 820 may also be used to discharge the power battery to a preset cut-off voltage at a preset standard discharge rate under each of the preset working conditions, and to leave the power battery standing for a second preset time period.

[0135] Optionally, the test module 820 may also be configured to allow the power battery to stand for a third preset time after being charged to each state of charge; and to allow the power battery to stand for a fourth preset time after continuing to charge the power battery for the first preset time.

[0136] Optionally, the calibration module 830 is specifically used to perform polynomial fitting on the charging relationship curves of the power battery for the multiple charge states under the multiple preset operating conditions to obtain a fitting coefficient matrix corresponding to the power battery; calculate the current charge voltage change rate based on the current charging voltage and the current charging capacity; calculate the charge voltage change matrix based on the current charging voltage and the fitting coefficient matrix; determine the error matrix based on the current charge voltage change rate and the charge voltage change matrix; and determine the target charge state based on the error matrix.

[0137] Optionally, the calibration module 830 may also be used to smooth the charging relationship curves of the power battery for the multiple charge states under the multiple preset operating conditions using a moving average smoothing method according to a preset window size, and the preset window size is used to characterize the number of sampling points in a single window during the movement process.

[0138] Optionally, the calibration module 830 is specifically used to determine the minimum element in the error matrix; if the charge voltage change rate of the minimum element is less than a second preset charge voltage change rate threshold, the charge state corresponding to the minimum element is determined to be the target charge state.

[0139] The above-mentioned device is used to execute the method provided by the aforementioned embodiment, and its implementation principle and technical effect are similar, which will not be repeated here.

[0140] Fig. 9 A schematic diagram of the structure of a battery management device provided in an embodiment of the present invention, the battery management device may be an electronic terminal such as the above-mentioned computer, such as Fig. 9 As shown, the device 900 includes:

[0141] Processor 910 , storage medium 920 and bus 930 . Processor 910 and storage medium 920 are communicatively connected via bus 930 .

[0142] The storage medium 920 stores machine-readable instructions executable by the processor 910 . When the electronic device is running, the processor 910 executes the machine-readable instructions to perform the power battery state of charge estimation method.

[0143] It should be understood that Fig. 9 The structure shown is only a schematic diagram of the structure of the electronic device. The electronic device may also include Fig. 9 More or fewer components as shown, or with Fig. 9 Different configurations are shown. Fig. 9 Each component shown in the figure can be implemented by hardware, software or a combination thereof.

[0144] An embodiment of the present invention further provides a computer-readable storage medium, in which a computer program is stored. When the computer program can be executed by a processor, the power battery state of charge estimation method described in the above method embodiment is implemented.

[0145] The computer-readable storage medium may be an electronic memory such as a flash memory, an EEPROM (electrically erasable programmable read-only memory), an EPROM, a hard disk, or a ROM. Optionally, the computer-readable storage medium includes a non-transitory computer-readable storage medium. The computer-readable storage medium has storage space for program codes that execute any of the method steps in the above method. These program codes may be read from or written to one or more computer program products. The program code may be compressed, for example, in an appropriate form.

[0146] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and a part of the module, program segment or code contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0147] In addition, the functional modules in the various embodiments of the present invention may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0148] If the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0149] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for estimating the state of charge of a power battery, characterized in that: include: Obtain the charging platform area of ​​the power battery in the target hybrid vehicle; Taking multiple charge states in the charging platform area as charging targets, controlling the engine in the target hybrid vehicle to generate pulse current under multiple preset working conditions, performing a charging test on the power battery, and obtaining a charging relationship curve of the power battery for the multiple charge states under each preset working condition, wherein the charging relationship curve of each charge state is used to characterize a relationship curve of voltage and capacity changes during the charging process taking each charge state as the charging target; Obtaining the current charging voltage and current charging capacity of the power battery; According to the current charging voltage, the current state of charge is calibrated using the charging relationship curves of the power battery for the multiple states of charge under the multiple preset working conditions to obtain a target state of charge of the power battery.

2. The method according to claim 1, characterized in that The step of obtaining the charging platform area of ​​the power battery in the target hybrid vehicle includes: Obtaining a preset relationship curve between the open circuit voltage and the state of charge of the power battery; Performing a derivation operation on the preset relationship curve to obtain a charge voltage change rate curve of the power battery, wherein the charge voltage change rate curve is used to characterize a change rate of the preset relationship curve; According to the charge change rate curve, a charge state interval in which the charge voltage change rate is less than or equal to a first preset charge voltage change rate threshold is determined as the charging platform area.

3. The method according to claim 1, characterized in that: The method of taking the multiple charge states in the charging platform area as charging targets, controlling the engine in the target hybrid vehicle to generate pulse current under multiple preset working conditions, performing a charging test on the power battery, and obtaining a charging relationship curve of the power battery for the multiple charge states under each preset working condition includes: Under each of the preset operating conditions, the ambient temperature of the power battery is adjusted to a target temperature within a preset temperature range; Under each of the preset working conditions, controlling the engine to generate and output a preset standard pulse current to charge the power battery to each state of charge; Under each of the preset operating conditions, at a rate in a preset rate range, the engine is controlled to generate and output a pulse current corresponding to the rate, and the power battery is continuously charged for a first preset time period; According to the electrical parameters of the power battery when charged to each state of charge, a charging relationship curve of the power battery for each state of charge under each preset working condition is drawn.

4. The method according to claim 3, characterized in that Before controlling the engine to generate and output a preset standard pulse current under each preset operating condition and charging the power battery to each state of charge, the method further includes: Under each of the preset operating conditions, the power battery is discharged to a preset cut-off voltage at a preset standard discharge rate and left to stand for a second preset time period.

5. The method according to claim 3, characterized in that: Under each of the preset operating conditions, at a rate in a preset rate range, the engine is controlled to generate and output a pulse current corresponding to the rate, and before the power battery continues to be charged for a first preset time, the method further includes: After the power battery is charged to each state of charge, standing for a third preset time; After continuing to charge the power battery for a first preset time period, the method further includes: Let stand for a fourth preset time period.

6. The method according to claim 1, characterized in that The step of calibrating the current state of charge by using the charging relationship curves of the power battery for the multiple states of charge under the multiple preset working conditions according to the current charging voltage to obtain the target state of charge of the power battery includes: Performing polynomial fitting on the charging relationship curves of the power battery for the multiple states of charge under the multiple preset operating conditions to obtain a fitting coefficient matrix corresponding to the power battery; Calculating a current charging voltage change rate according to the current charging voltage and the current charging capacity; Calculating a charge voltage variation matrix according to the current charge voltage and the fitting coefficient matrix; Determining an error matrix according to the current charge voltage change rate and the charge voltage change matrix; The target state of charge is determined according to the error matrix.

7. The method according to claim 6, characterized in that Before performing polynomial fitting on the charging relationship curves of the power battery for the multiple states of charge under the multiple preset operating conditions to obtain a fitting coefficient matrix corresponding to the power battery, the method further includes: According to the preset window size, a moving average smoothing method is adopted to smooth the charging relationship curves of the power battery for the multiple charge states under the multiple preset working conditions. The preset window size is used to characterize the number of sampling points in a single window during the moving process.

8. The method according to claim 6, characterized in that The step of determining the target state of charge according to the error matrix includes: Determining a minimum element in the error matrix; If the charge voltage change rate of the minimum element is less than a second preset charge voltage change rate threshold, the charge state corresponding to the minimum element is determined to be the target charge state.

9. A battery management device, characterized in that: include: A processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, the processor and the storage medium communicate via the bus, and the processor executes the machine-readable instructions to perform the method as claimed in any one of claims 1 to 8.

10. A hybrid vehicle, characterized in that: include: A power battery, an engine and a battery management device as described in claim 9 above, wherein the power battery and the engine are electrically connected, and the battery management device is also communicatively connected between the power battery and the engine, and the battery management device is used to execute the method as described in any one of claims 1-8.

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