WO2024020842A1

WO2024020842A1 - Battery power control method and apparatus, and device and storage medium

Info

Publication number: WO2024020842A1
Application number: PCT/CN2022/108187
Authority: WO
Inventors: 倪铭; 张世昌; 严明伟
Original assignee: 宁德时代新能源科技股份有限公司
Priority date: 2022-07-27
Filing date: 2022-07-27
Publication date: 2024-02-01

Abstract

Provided in the embodiments of the present application are a battery power control method and apparatus, and a device and a storage medium. The method comprises: acquiring, in real time, electrical parameters of a battery; and performing closed-loop control on the allowable power of the battery according to the electrical parameters. In the present application, an allowable power is adaptively controlled according to electrical parameters, and the allowable power of a battery cell is provided on the basis of the actual capacity of the battery cell, such that the energy of the battery is more fully exerted, the problem of undervoltage under any operating condition and any battery cell state is prevented from occurring, and the available power of the battery can be exerted to the maximum extent with no undervoltage. With regard to low-temperature and low-SOC emergency acceleration or emergency deceleration, abnormal aging of a battery cell, etc., an under-voltage caused by a sharp voltage drop resulting from a large-current operating condition can be effectively avoided, and it is ensured that the energy of a battery can be fully exerted, such that the acceleration capability of an electric device in a low-temperature and low-SOC state is better.

Description

Battery power control method, device, equipment and storage medium

Technical field

The present application relates to the field of battery technology, and in particular to a battery power control method, device, equipment and storage medium.

Background technique

At present, batteries are widely used in electric transportation, military equipment, aerospace and other fields. During the use of batteries, under-voltage breakdown may occur. Therefore, the power of the battery needs to be controlled to avoid under-voltage breakdown.

Related technologies basically use open-loop control of battery power based on voltage, which can only passively control power according to voltage changes, and cannot be applied to situations where the cell voltage drops sharply, such as low temperature and low SOC (Sate of Charge). , state of charge), it cannot be applied to situations where abnormal cell DCR causes a sharp drop in cell voltage, etc.

Contents of the invention

Embodiments of the present application provide a battery power control method, device, equipment and storage medium to solve the undervoltage problem that may occur under any working conditions and any cell status.

In a first aspect, embodiments of the present application provide a battery power control method, including:

Obtain battery electrical parameters in real time;

According to the electrical parameters, the allowable power of the battery is controlled in a closed loop.

In this embodiment, the allowable power is closed-loop controlled based on the electrical parameters of the battery, and does not rely on the pre-calibrated voltage threshold or the preset power map measured when the battery is fully resting. The electrical parameters adaptively control the allowable power, and the closed-loop control makes the power control more accurate and can maximize the battery's allowable power without undervoltage. This method can be applied to batteries of any system, and can solve the under-voltage problem that may occur under any working conditions and cell conditions, avoid the breakdown of electrical equipment due to battery under-voltage, and reduce customer complaints caused by breakdown due to under-voltage. , improve product competitiveness.

In some embodiments of the present application, the closed-loop control of the allowable power of the battery according to the electrical parameters includes:

Calculate the voltage error value of the battery according to the minimum cell voltage included in the electrical parameters;

Based on the voltage error value, the allowable power of the battery is controlled in a closed loop.

In this embodiment, undervoltage occurs when the minimum cell voltage is less than the undervoltage threshold, so the voltage error needs to be controlled. Closed-loop control of allowable power based on voltage error. Changes in allowable power will change the minimum cell voltage of the battery, thereby changing the voltage error value. The changed voltage error value is used as an input parameter for power closed-loop control, affecting many Using power control, the allowable power is adaptively controlled based on the voltage error value. Combining voltage error control and allowable power control greatly improves the control effect. The undervoltage threshold under different cell temperatures can well avoid undervoltage. It is suitable for batteries of any system and can avoid undervoltage problems under any working conditions and any cell status. Power closed-loop feedback adaptive adjustment based on the actual minimum cell voltage and decoupled control with SOC can avoid undervoltage problems caused by falsely high SOC.

In some embodiments of the present application, the closed-loop control of the allowed power of the battery based on the voltage error value includes:

Based on the voltage error value and the electrical parameters, calculate the first allowable power of the battery through a PID algorithm;

Close-loop control is performed on the allowable power of the battery according to the first allowable power and the electrical parameters.

In this embodiment, the PID algorithm can be used to dynamically calculate the first allowable power of the battery in real time based on the voltage error value and battery cell parameters, and use the first allowable power to perform closed-loop control, thereby realizing adaptive power generation based on the voltage error value. Control the allowable power. Combining voltage error control and allowable power control greatly improves the control effect. The battery SOC is not used for power control to avoid the problem of undervoltage caused by high allowable power caused by SOC error.

In some embodiments of the present application, calculating the first allowable power of the battery through a PID algorithm based on the voltage error value and the electrical parameters includes:

Based on the electrical parameters, adjust the calculation coefficient of the PID algorithm;

Based on the voltage error value, the cell impedance included in the electrical parameters, and the adjusted calculation coefficient, the first allowable power of the battery is calculated through the PID algorithm.

In this embodiment, since the first allowable power is calculated based on the voltage error value, and the voltage error value is calculated based on the minimum cell voltage, the size of the first allowable power is equal to the size of the minimum cell voltage. Strong correlation. The size of the minimum cell voltage is related to the size of the battery SOC. Therefore, in different battery SOC ranges, if a fixed calculation coefficient is used to calculate the first allowable power, the calculated first allowable power will be too large or biased. If the first allowable power is too small, the subsequent power control may fail if the first allowable power is too large, while if the first allowable power is too small, the power of the battery may be limited. Before calculating the first allowable power, adjusting the calculation coefficient of the PID algorithm can make the calculation coefficient adapt to the cell state, optimize the calculation coefficient, improve the accuracy of the calculated first allowable power, and adjust the power adaptively. , which can not only avoid power control failure, but also maximize the energy of the battery without undervoltage.

In some embodiments of the present application, adjusting the calculation coefficient of the PID algorithm based on the electrical parameters includes:

Based on the battery SOC or minimum cell voltage included in the electrical parameters, determine the target calculation coefficient that currently needs to be adjusted;

The target calculation coefficient is adjusted based on the battery SOC or the minimum cell voltage.

In this embodiment, the calculation coefficients of the PID algorithm include a proportional coefficient and an integral coefficient. In different SOC intervals, the calculation coefficients that affect the accuracy of the first allowable power calculation are different. Therefore, the current target calculation coefficient that needs to be adjusted is first determined based on the battery SOC or the minimum cell voltage, and then the target calculation coefficient is adjusted in a targeted manner. This can improve the accuracy of the adjustment calculation coefficient.

In some embodiments of the present application, determining the target calculation coefficient that currently needs to be adjusted based on the battery SOC or minimum cell voltage included in the electrical parameters includes:

If the battery SOC belongs to the preset high-end SOC range, or the minimum cell voltage belongs to the preset high-end voltage range, or the battery SOC is less than or equal to the preset end SOC threshold, or the minimum cell voltage is less than is equal to the preset terminal voltage threshold, then it is determined that the current target calculation coefficient that needs to be adjusted is the integral coefficient of the PID algorithm;

If the battery SOC belongs to the preset low-end SOC range, or the minimum cell voltage belongs to the preset low-end voltage range, then it is determined that the target calculation coefficient that currently needs to be adjusted is the proportional coefficient of the PID algorithm.

In this embodiment, based on the impact of different calculation coefficients on the calculation results of the PID algorithm under different SOC intervals or different voltage intervals, the target calculation coefficients that need to be adjusted under different SOC intervals or different voltage intervals are determined. During the application process, the target calculation coefficient is determined based on the current battery SOC or minimum cell voltage. It is possible to determine the target calculation coefficient that needs to be adjusted based on the cell characteristics and improve the accuracy of calculation coefficient adjustment.

In some embodiments of the present application, adjusting the target calculation coefficient based on the battery SOC or minimum cell voltage includes:

Obtain the target calculation coefficient corresponding to the battery SOC from the mapping relationship between the preset SOC interval and the target calculation coefficient; or,

The target calculation coefficient corresponding to the minimum cell voltage is obtained from the mapping relationship between the preset voltage interval and the target calculation coefficient.

In this embodiment, through the mapping relationship between the preset SOC interval and the value of the target calculation coefficient, or the mapping relationship between the preset voltage interval and the value of the target calculation coefficient, the current battery SOC can be or the minimum cell voltage, and quickly obtain the value of the corresponding target calculation coefficient, which improves the efficiency of adjusting the target calculation coefficient.

If the target calculation coefficient is the integral coefficient, obtain the preset adjustment coefficient corresponding to the battery SOC or the minimum cell voltage, and calculate the preset adjustment in each iteration cycle of the PID algorithm. The product of the coefficient and the integration coefficient corresponding to the previous iteration cycle;

Among them, if the battery SOC belongs to the preset high-end SOC range, or the minimum cell voltage belongs to the preset high-end voltage range, then the preset adjustment coefficient is less than 1; if the battery SOC is less than or equal to the preset terminal SOC threshold, Or, if the minimum cell voltage is less than or equal to the preset terminal voltage threshold, then the preset adjustment coefficient is greater than 1.

In this embodiment, in the preset high-end SOC interval or the preset high-end voltage interval, the preset adjustment coefficient is less than 1, and the integral coefficient of each iteration is multiplied by the preset adjustment coefficient less than 1. As the number of iterations increases, the integral coefficient will increase Keep getting smaller. In this way, when the battery SOC is high and the minimum cell voltage is also high, it can effectively avoid the continuous increase of the integral value, avoid the final calculated first allowable power being too large, and ensure that subsequent power control will not fail. When the current battery SOC is less than or equal to the preset end SOC threshold, or the minimum cell voltage is less than or equal to the preset end voltage threshold, the preset adjustment coefficient is greater than 1, and the integral coefficient of each iteration is multiplied by the preset adjustment greater than 1. Coefficient, the integral coefficient will continue to increase as the number of iterations increases. In this way, when the battery is almost out of power, the overall control error can be converged. When the actual power follows the allowable power response, the minimum cell voltage can finally be consistent with the controlled undervoltage threshold.

In some embodiments of the present application, the closed-loop control of the allowed power of the battery based on the first allowed power and the electrical parameters includes:

According to the cell temperature and battery SOC included in the electrical parameters, obtain the corresponding initial allowable power from the preset power map table;

If the first allowed power is less than the initial allowed power, the battery is controlled to reduce the current actual power to the first allowed power.

In this embodiment, if the first allowed power is less than the initial allowed power, it means that the initial allowed power given in the preset power map table is too high. If you continue to respond with the initial allowed power, it will Undervoltage occurs. Therefore, the first allowable power is used as the final allowable power, and the battery is controlled to reduce from the current actual power to the first allowable power, thereby effectively avoiding the undervoltage problem caused by the high initial allowable power. When the first allowable power is smaller than the initial allowable power as the intervention time of power control, the available capacity of the battery core can be maximized without under-voltage.

Based on the electrical parameters, estimate a second allowable power of the battery;

Close-loop control is performed on the allowed power of the battery according to the first allowed power, the second allowed power and the electrical parameters.

In this embodiment, based on the first allowable power calculated using the PID algorithm based on the voltage error value, the second allowable power is estimated based on the electrical parameters of the battery, combining the first allowable power and the second allowable power. The power is controlled in a closed loop, which further improves the accuracy of the allowable power control and avoids undervoltage problems that may occur under any circumstances.

In some embodiments of the present application, estimating the second allowable power of the battery based on the electrical parameters includes:

Based on the battery core temperature included in the electrical parameter, determine the undervoltage threshold corresponding to the battery core temperature;

Calculate the difference between the minimum cell voltage included in the electrical parameters and the undervoltage threshold;

The second allowable power of the battery is calculated based on the difference, the cell impedance included in the electrical parameter, and the current overall voltage of the battery.

In this embodiment, the second allowable power of the battery is estimated based on the electrical parameters of the battery, so that the estimated second allowable power is adapted to the cell characteristics of the battery, and the second allowable power is used in combination with the dynamic use of the PID algorithm. The calculated first allowable power is subject to closed-loop control, making the control of the allowable power more accurate and effectively avoiding undervoltage problems.

In some embodiments of the present application, the closed-loop control of the allowed power of the battery based on the first allowed power, the second allowed power and the electrical parameters includes:

Determine the minimum value of the first allowed power and the second allowed power;

If the minimum value is less than the initial allowed power, the battery is controlled to reduce the current actual power to the minimum value.

In this embodiment, since the estimated second allowed power may have errors, and the first allowed power calculated using the PID algorithm may also have errors, the minimum of the first allowed power and the second allowed power is used. The value is used as the final allowable power to reduce the actual power of the battery to the minimum value. This makes the control of the allowable power more precise and more accurate, and can avoid undervoltage problems that may occur under any working conditions and any cell status.

In some embodiments of the present application, controlling the battery to reduce the current actual power to the minimum value includes:

If both the first allowed power and the second allowed power are less than the initial allowed power, the battery is controlled to reduce from the current actual power to the first allowed power and the second allowed power. Use the second smallest value in power, and then reduce it from the second smallest value to the minimum value.

In this embodiment, the first allowable power is reduced to the second smallest value among the first allowable power and the second allowable power, and then the second smallest value is reduced to the minimum value, so as to adapt to the power reduction requirements of the electrical equipment and enable the power to be reduced. Changes are smoother, avoiding excessive instantaneous changes in power that may cause sudden changes in the operating status of electrical equipment, and improving user experience.

In some embodiments of the present application, the method further includes:

In the process of reducing the battery power, the battery power is controlled to be reduced at a preset reduction rate. Reducing battery power according to a preset reduction rate can make the power reduction process smoother and avoid sudden changes in battery power.

In some embodiments of the present application, calculating the voltage error value of the battery based on the minimum cell voltage included in the electrical parameters includes:

According to the battery core temperature included in the electrical parameter, determine the undervoltage threshold corresponding to the battery core temperature;

Calculate the difference between the minimum cell voltage included in the electrical parameters and the undervoltage threshold to obtain the voltage error value of the battery.

In this embodiment, the lowest cell temperature is used to determine the undervoltage threshold, and the minimum cell voltage is subtracted from the undervoltage threshold to obtain a voltage error value. This voltage error value is subsequently used to perform closed-loop control of the allowable power. Such control prevents the cell with the lowest temperature and the cell with the smallest voltage from under-voltage, thereby preventing other cells with higher temperature and voltage from under-voltage, which can effectively prevent the battery from being damaged at any time under any working conditions. An undervoltage problem occurs in the battery cell state.

In some embodiments of the present application, the electrical parameters include the cell impedance of the battery. Obtaining the cell impedance of the battery includes:

Simulate the current operating conditions of the battery through a preset equivalent circuit model to obtain the corresponding first-order high-frequency impedance, second-order low-frequency impedance and ohmic impedance of the battery;

Calculate the sum of the first-order high-frequency impedance, the second-order low-frequency impedance and the ohmic impedance to obtain the cell impedance of the battery.

The current operating conditions of the battery are simulated based on the preset equivalent circuit model, so that each parameter for calculating the cell impedance is obtained based on the identification of the actual operating conditions of the battery, thus making the calculated cell impedance highly accurate. Using the preset equivalent circuit model for simulation eliminates the need for actual measurement and calibration of the cell impedance in advance, which simplifies the processing process and improves the efficiency of obtaining the cell impedance.

Calculate the cell impedance of the battery according to the current current of the battery included in the electrical parameters and the change in cell voltage under the current current;

Obtain the preset calibration impedance corresponding to the current current, perform a weighted sum of the preset calibration impedance and the calculated cell impedance, and obtain the final cell impedance.

First use the collected battery current and cell voltage to calculate the cell impedance, and then perform a weighted sum of the calculated cell voltage and the preset calibrated impedance measured in advance, which greatly reduces the need for calculations using current and cell voltage. The influence of the calculation error improves the accuracy of the cell impedance, which in turn helps improve the accuracy of subsequent power control based on the cell impedance.

In a second aspect, embodiments of the present application provide a battery power control device, including:

Parameter acquisition module, used to obtain the electrical parameters of the battery in real time;

A power control module, configured to perform closed-loop control on the allowable power of the battery according to the electrical parameters.

In a third aspect, embodiments of the present application provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program , implement the method described in the first aspect.

In a fourth aspect, embodiments of the present application provide an electrical device, including the electronic device described in the third aspect.

In a fifth aspect, embodiments of the present application provide a computer-readable storage medium that stores a computer program. When the computer program is executed by a processor, the method described in the first aspect is implemented.

The above description is only an overview of the technical solutions of the present application. In order to have a clearer understanding of the technical means of the present application, they can be implemented according to the content of the description, and in order to make the above and other purposes, features and advantages of the present application more obvious and understandable. , the specific implementation methods of the present application are specifically listed below.

Description of drawings

In order to explain the technical solutions of the embodiments of the present application more clearly, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. Those of ordinary skill in the art can also obtain other drawings based on the drawings without exerting creative efforts.

FIG. 1 is a schematic flowchart of a battery power control method provided by an embodiment of the present application.

FIG. 2 is another schematic flowchart of a battery power control method provided by an embodiment of the present application.

FIG. 3 is a comparison diagram of the effects of power control according to the embodiment of the present application and related technologies.

Figure 4 is a voltage curve diagram under power control of the embodiment of the present application and related technologies shown in Figure 3;

5 and 6 are comparison diagrams showing the effects of power control between the embodiments of the present application and related technologies from the perspective of current changes.

FIG. 7 is a schematic structural diagram of a battery power control device provided by an embodiment of the present application.

FIG. 8 is a schematic structural diagram of an electronic device provided by an embodiment of the present application.

Detailed ways

The embodiments of the present application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

In the description of this application, it should be noted that, unless otherwise stated, "plurality" means more than two; the terms "upper", "lower", "left", "right", "inside", " The orientation or positional relationship indicated such as "outside" is only for the convenience of describing the present application and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. Application restrictions. Furthermore, the terms "first," "second," "third," etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable error range. "Parallel" is not parallel in the strict sense, but within the allowable error range.

The directional words appearing in the following description are the directions shown in the figures and do not limit the specific structure of the present application. In the description of this application, it should also be noted that, unless otherwise clearly stated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection or a removable connection. Detachable connection, or integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this application may be understood based on specific circumstances.

Currently, batteries are widely used in electric vehicles, military equipment, aerospace and other fields. During the use of the battery, the BMS (Battery Management System) will control the power of the battery to ensure that the electrical equipment where the battery is located can output power smoothly during operation and meet the normal use conditions of the electrical equipment. . Taking electric vehicles as an example, power control of the batteries of electric vehicles can meet the power requirements of normal driving conditions such as acceleration, constant speed, and hill climbing during the driving of electric vehicles.

During the operation of electrical equipment, the battery may be under-voltage due to many reasons, causing the electrical equipment to break down. For example, there is a sampling error in the minimum cell voltage of the battery, causing an undervoltage false alarm when the actual minimum cell voltage is not lower than the undervoltage threshold, causing the electrical equipment to break down. For another example, during the operation of electrical equipment, the preset power map table is queried based on the cell temperature and battery SOC to obtain the battery's allowable power, and the battery operation is controlled based on the queried allowable power. However, there are errors in the calculation of the battery SOC. When the calculated battery SOC is too high, the queried allowable power is also too high. If the actual power does not reach the high allowable power, the battery will be under-voltage and break down. For another example, the preset power map table is the power measured at different cell temperatures and different battery SOCs when the battery is fully resting. However, during actual use of the battery, the cells will produce polarization impedance, resulting in many actual The power used is inconsistent with the allowed power in the preset power map table, which may cause the battery to malfunction due to undervoltage. In addition, some control strategies of the BMS may have flaws that may cause the battery to malfunction due to under-voltage. For example, the BMS needs to control the voltage to a certain value, but due to errors in the control strategy itself, it is actually unable to control the voltage to this value, which may cause The battery broke down due to low battery voltage. Here are just a few examples that can lead to battery undervoltage and breakdown. In actual applications, there may be many other reasons that lead to undervoltage and breakdown.

In order to ensure that battery under-voltage breakdown does not occur during the operation of electrical equipment, the output power of the battery needs to be limited. Currently, in the related technology, the voltage thresholds that need to be controlled under different cell temperatures are tested and calibrated in advance, and the minimum cell voltage of the battery is obtained during the operation of the electrical equipment. When the minimum cell voltage reaches the set voltage threshold When the battery is running, the allowable power of the battery is limited to avoid undervoltage.

However, the inventor of this application found that the accuracy of power control in the above related technologies depends on the accuracy of the calibrated voltage threshold. If the voltage threshold is calibrated too high, the power will be limited when the minimum cell voltage is high, affecting power consumption. Device usage experience. If the voltage threshold is calibrated too low, it may be too late to limit the power, significantly increasing the risk of undervoltage. Therefore, taking the minimum cell voltage to reach the calibrated voltage threshold as the intervention time of power control may limit the power of the battery and may also increase the risk of undervoltage. Moreover, related technologies can only perform power control passively based on changes in the minimum cell voltage and rely on calibrated voltage thresholds, which can avoid undervoltage under normal and mild operating conditions of electrical equipment. Usually, the maximum power that can be used by electrical equipment without any restrictions such as faults is the allowable value in the preset power map table. However, the preset power map table is obtained by testing current or power under static conditions. , without considering the cumulative polarization effect in actual operating conditions, the power given by the preset power map table may be too high in some scenarios, resulting in a significant increase in undervoltage. Therefore, the related technology is suitable for some special working conditions or abnormal cell status, such as emergency acceleration or emergency deceleration at low temperature and low SOC, abnormal cell impedance causing a sharp drop in cell voltage, etc. Under these special circumstances, it is difficult to avoid battery undervoltage and breakdown using the above-mentioned related technologies.

In order to further improve power control, completely solve the under-voltage problem that may occur under any working conditions and any cell status, and find the best time for power control intervention, so as to not limit the power play on the basis of sufficient cell capacity, in the cell When the capacity is insufficient, the battery's allowable power can be maximized without under-voltage. With this as the research and development goal, the inventor of the present application conducted in-depth research and proposed a battery power control method, which obtains the electrical parameters of the battery in real time during battery use. According to the electrical parameters of the battery, the allowable power of the battery is controlled in a closed loop.

The closed-loop control of the allowable power is based on the electrical parameters of the battery. It does not rely on the pre-calibrated voltage threshold or the preset power map measured when the battery is fully resting. It is adaptively controlled based on the electrical parameters of the battery. Allowable power, closed-loop control makes power control more accurate and can maximize the allowable power of the battery without undervoltage. This method can be applied to batteries of any system, and can solve the under-voltage problem that may occur under any working conditions and cell conditions, avoid the breakdown of electrical equipment due to battery under-voltage, and reduce customer complaints caused by breakdown due to under-voltage. , improve product competitiveness.

The battery power control method provided by the embodiments of this application can be applied to batteries of any system. The battery can be a single cell, a battery module, a battery pack, etc. The electrical equipment to which this method is applicable may be, but is not limited to, electric toys with batteries, electric tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, spaceships, etc.

There is a battery installed in the electrical equipment. The discharge of the battery provides power for the electrical equipment. When the battery power is low, the battery needs to be charged. During the battery charging and discharging process, the charging and discharging power of the battery needs to comply with the allowable power of the battery. The allowable power indicates the battery's ability to withstand the charging and discharging power. When the voltage of the battery is too low, it may cause battery undervoltage and cause the electrical equipment to break down. Therefore, the allowable power of the battery needs to be limited to avoid battery undervoltage. For batteries in electrical equipment, the power control method provided in the embodiment of this application can be used to limit the allowable power of the battery.

Embodiments of the present application provide a battery power control method, which provides closed-loop control of the allowable power based on the electrical parameters of the battery, and can solve the undervoltage problem that may occur under any working conditions and any cell status. Referring to the flow chart of the battery power control method shown in Figure 1, the method specifically includes the following steps:

Step 101: Obtain the electrical parameters of the battery in real time.

The execution subject of the embodiment of this application is the controller in the electrical equipment. The controller can be a BMS, VCU (Vehicle Control Unit, vehicle controller) or a domain controller.

The battery can be a single cell, a battery module composed of multiple cells connected in series or parallel, a battery pack composed of multiple battery modules connected in series or parallel, or a larger battery pack composed of multiple battery packs connected in series or parallel. etc.

The electrical parameters of the battery are the various electrochemical parameters displayed by the battery during rest or use, such as current, cell voltage, cell temperature, battery SOC, cell impedance, etc. Among them, the BMS can detect the cell voltage of each single cell in the battery. In the embodiment of the present application, the electrical parameters of the battery may include the cell voltage of each single cell, or may only include all single cells. The minimum value among the cell voltages of the core is called the minimum cell voltage in the embodiment of this application. For the case where the electrical parameters include the cell voltage of each single cell, when the minimum cell voltage needs to be used later, the minimum cell voltage can be selected from the cell voltage of each single cell.

One or more temperature sensors are provided in the battery, and these temperature sensors are used to detect the cell temperature. The cell temperature included in the above electrical parameters may include the cell temperature detected by each temperature sensor, or may only include the minimum value of each cell temperature detected. For the case where the electrical parameters include the detected temperature of each cell, when the minimum cell temperature needs to be used later, the minimum value can be selected from each cell temperature.

In some embodiments, the cell impedance can be calculated from other electrical parameters. Specifically, it is based on the currently collected current I of the battery and the cell voltage of the same cell at different times under this current I. Based on the cell voltage of the cell at different times, calculate the voltage change ΔU of the cell under the current current I, then the cell impedance DCR1 of the cell = ΔU/I, and determine the calculated cell impedance DCR1 is the cell impedance included in the above electrical parameters. Using the collected current and voltage to calculate the cell impedance, the cell impedance can be quickly obtained.

In other embodiments, considering that there are inevitable calculation errors in calculating the cell impedance through the above method, in order to improve the accuracy of the cell impedance, the embodiments of the present application also compare the above calculated cell impedance with the measured calibrated cell impedance. Impedance is weighted. In the embodiment of this application, the cell impedance is measured and calibrated in advance. Specifically, according to the HPPC (Hybrid PulsePower Characteristic, hybrid power pulse characteristics) test conditions, the required cell impedance DCR2 is extracted based on the cell voltage change under a certain current excitation. , in the embodiment of this application, the calibrated cell impedance is called the preset calibrated impedance. After calibrating the cell impedance DCR2 corresponding to different currents, the mapping relationship between different currents and the preset calibrated impedance is pre-configured in the controller of the electrical equipment (such as BMS). For the cell impedance DCR1 calculated in the above method, based on the current current I corresponding to the cell impedance DCR1, the preset calibration impedance DCR2 corresponding to the current I is obtained from the above-mentioned preconfigured mapping relationship. Then perform a weighted sum of the preset calibrated impedance DCR2 and the calculated cell impedance DCR1 to obtain the final cell impedance.

The final cell impedance DCR=k1*DCR1+k2*DCR2, the coefficients k1 and k2 can be set based on experience, such as k1 is 0.6, k2 is 0.4, or k1 is 0.4, k2 is 0.6, etc.

In other embodiments of the present application, the usage conditions of the battery can also be simulated based on a preset equivalent circuit model, and the cell impedance is determined based on the simulation results. Among them, the preset equivalent circuit model refers to using a relatively simple circuit result to replace the circuit structure in which the battery is actually used. The replaced preset equivalent circuit model maintains the same effect as the original circuit structure of the battery. The preset equivalent circuit model can be a first-order RC equivalent circuit model, a second-order RC equivalent circuit model, etc.

Specifically, the current operating conditions of the battery are simulated through a preset equivalent circuit model, and the first-order high-frequency impedance, second-order low-frequency impedance, and ohmic impedance corresponding to the battery are obtained. Calculate the sum of the first-order high-frequency impedance, the second-order low-frequency impedance and the ohmic impedance to obtain the cell impedance of the battery.

The first-order high-frequency impedance is expressed as

The second-order low-frequency impedance is expressed as

Ohmic impedance is represented by R ₀ . Cell impedance

Among them, R ₁ and R ₂ are the initial state values of the first-order and second-order impedance, τ1 and τ2 are time constants, N is the sampling step size, and ΔT is the sampling period.

For each cell in the battery, the cell impedance of each cell can be determined using any of the above embodiments. The electrical parameters in step 101 can include the cell impedance of each cell. Alternatively, the cell impedance of the cell corresponding to the current minimum cell voltage can also be calculated only in the above manner, and the electrical parameters only include the cell impedance of the cell corresponding to the current minimum cell voltage.

During the use of the battery, the controller obtains the electrical parameters of the battery in real time. The controller can obtain the electrical parameters of the battery every certain period. The duration of this period can be milliseconds or seconds. The embodiment of the present application does not Limit the value of this cycle length, which can be set according to needs in actual applications.

Step 102: Perform closed-loop control on the allowable power of the battery based on the electrical parameters.

The controller performs closed-loop control on the allowable power of the battery based on the electrical parameters obtained in step 101. Closed-loop control refers to a control relationship in which the controlled output quantity returns to the input terminal as the control in a certain way and exerts a control influence on the input terminal. It is a system control method with feedback information. In the embodiment of the present application, the allowable power of the battery is controlled according to the electrical parameters of the battery. Changes in the allowable power will change the electrical parameters of the battery, and the changes in the electrical parameters are used as input parameters of the closed-loop control, affecting The control of the allowable power realizes the adaptive control of the allowable power based on the electrical parameters, and provides the allowable power of the battery core based on the actual capacity of the battery core, so that the energy of the battery can be fully exerted and avoid arbitrary working conditions and arbitrary power. It can prevent under-voltage problems when the battery is under voltage, and can maximize the available power of the battery without under-voltage. For electric vehicles, emergency acceleration or deceleration at low temperatures, low SOC, abnormal aging of battery cells, etc., and undervoltage caused by sharp voltage drops caused by high current operating conditions, can be effectively avoided and ensure that the battery energy can be fully charged. The electric vehicle that implements the method provided by the embodiments of the present application has better acceleration capabilities in low-temperature and low-SOC states.

In some embodiments of the present application, voltage error control is combined with power control. Specifically, the voltage error value of the battery is calculated based on the minimum cell voltage included in the electrical parameters of the battery. Based on the voltage error value, the allowable power of the battery is controlled in a closed loop.

The voltage error value is the difference between the minimum cell voltage of the battery and the current undervoltage threshold. The embodiment of the present application has pre-tested and calibrated the undervoltage threshold at different cell temperatures, and pre-configured the mapping relationship between the cell temperature and the undervoltage threshold in the controller of the electrical equipment.

Undervoltage occurs when the minimum cell voltage is less than the undervoltage threshold, so the voltage error needs to be controlled. Closed-loop control of allowable power based on voltage error. Changes in allowable power will change the minimum cell voltage of the battery, thereby changing the voltage error value. The changed voltage error value is used as an input parameter for power closed-loop control, affecting many Using power control, the allowable power is adaptively controlled based on the voltage error value. Combining voltage error control and allowable power control greatly improves the control effect. The undervoltage threshold under different cell temperatures can well avoid undervoltage. It is suitable for batteries of any system and can avoid undervoltage problems under any working conditions and any cell status. Power closed-loop feedback adaptive adjustment based on the actual minimum cell voltage and decoupled control with SOC can avoid undervoltage problems caused by falsely high SOC.

In some embodiments, the process of closed-loop control of the allowable power based on the voltage error value is specifically based on the voltage error value and electrical parameters, and the PID (Proportion Integral Differential) algorithm is used to calculate the first allowable power of the battery. According to the first allowable power and electrical parameters, the allowable power of the battery is controlled in a closed loop.

Among them, the PID algorithm is a control algorithm that combines proportion, integral and differential. Based on the voltage error value and cell parameters, the PID algorithm can be used to dynamically calculate the first allowable power of the battery in real time, and use the first allowable power for closed-loop control, achieving adaptive control of the allowable power based on the voltage error value. Combining voltage error control and allowable power control greatly improves the control effect. The battery SOC is not used for power control to avoid the problem of undervoltage caused by high allowable power caused by SOC error.

The calculation process of the above voltage error value is to determine the undervoltage threshold corresponding to the battery core temperature according to the battery core temperature included in the electrical parameters. Calculate the difference between the minimum cell voltage included in the electrical parameters and the undervoltage threshold to obtain the battery voltage error value.

The cell temperature used to determine the undervoltage threshold may be the minimum value among all currently detected cell temperatures. According to the cell temperature, the corresponding undervoltage threshold is obtained from the preset mapping relationship between the cell temperature and the undervoltage threshold. Calculate the difference between the current minimum cell voltage and the undervoltage threshold to obtain the voltage error value. That is, the voltage error value error=U _real -U _lim , where U _real is the minimum cell voltage and U _lim is the undervoltage threshold.

The lowest cell temperature is used to determine the undervoltage threshold, and the minimum cell voltage is used to subtract the undervoltage threshold to obtain the voltage error value. This voltage error value is subsequently used to perform closed-loop control of the allowable power. Such control prevents the cell with the lowest temperature and the cell with the smallest voltage from under-voltage, thereby preventing other cells with higher temperature and voltage from under-voltage, which can effectively prevent the battery from under-voltage under any working conditions and at any time. An undervoltage problem occurs in the battery cell state.

After calculating the voltage error value through the above method, input the voltage error value into the PID algorithm, and use the formula

Calculate the first allowable power. Among them, P is the first allowable power, k _p is the proportional coefficient, k _i is the integral coefficient, R _all is the cell impedance, and N is the number of iterations.

Among them, the cell impedance R _all is the cell impedance included in the electrical parameters in step 101, and the cell impedance is the impedance of the cell corresponding to the minimum cell voltage. In the embodiment of this application, the above proportional coefficient k _p and integral coefficient k _i are called calculation coefficients of the PID algorithm.

In some embodiments of the present application, before calculating the first allowable power, the calculation coefficient of the PID algorithm is adjusted based on the electrical parameters. Based on the voltage error value, the cell impedance included in the electrical parameters, and the adjusted calculation coefficient, the first allowable power of the battery is calculated through the PID algorithm.

Since the first allowable power P is calculated based on the voltage error value, and the voltage error value is calculated based on the minimum cell voltage, the size of the first allowable power P is strongly related to the size of the minimum cell voltage. The size of the minimum cell voltage is related to the size of the battery SOC. Therefore, in different battery SOC ranges, if a fixed calculation coefficient is used to calculate the first allowable power, the calculated first allowable power will be too large or biased. If the first allowable power is too small, the subsequent power control may fail if the first allowable power is too large, while if the first allowable power is too small, the power of the battery may be limited. Before calculating the first allowable power, adjusting the calculation coefficient of the PID algorithm can make the calculation coefficient adapt to the cell state, optimize the calculation coefficient, improve the accuracy of the calculated first allowable power, and adjust the power adaptively. , which can not only avoid power control failure, but also maximize the energy of the battery without undervoltage.

For adjusting the calculation coefficient of the PID algorithm, first determine the current target calculation coefficient that needs to be adjusted based on the battery SOC or minimum cell voltage included in the electrical parameters. Based on the battery SOC or minimum cell voltage, the target calculation coefficient is adjusted.

The calculation coefficients of the PID algorithm include proportional coefficients and integral coefficients. In different SOC intervals, the calculation coefficients that affect the accuracy of the first allowable power calculation are different. Therefore, the current target calculation coefficient that needs to be adjusted is first determined based on the battery SOC or the minimum cell voltage, and then the target calculation coefficient is adjusted in a targeted manner. This can improve the accuracy of the adjustment calculation coefficient.

The calculation coefficients that affect the PID calculation accuracy are different in different SOC intervals or different voltage intervals. The embodiments of this application test through experiments the target calculation coefficients that need to be adjusted corresponding to different SOC intervals or different voltage intervals, and set them in the controller of the electrical equipment. The mapping relationship between different SOC intervals and target calculation coefficients, and the mapping relationship between different voltage intervals and target calculation coefficients are pre-configured.

Among them, the different SOC intervals include a preset high-end SOC interval, a preset low-end SOC interval and a preset terminal SOC interval. The lower limit of the preset high-end SOC interval is greater than the upper limit of the preset low-end SOC interval. The preset low-end SOC interval The lower limit of the SOC interval is greater than the upper limit of the preset end SOC interval, and the upper limit of the preset end SOC interval is called the preset end SOC threshold. For example, the preset high-end SOC interval can be (60%, 100%], the preset low-end SOC interval can be (10%, 60%], and the preset terminal SOC interval can be [0, 10%]. This application implements This example does not limit the specific division of the preset high-end SOC interval, the preset low-end SOC interval, and the preset terminal SOC interval, which can be set according to needs in actual applications.

Different voltage intervals include a preset high-end voltage interval, a preset low-end voltage interval and a preset end voltage interval. The lower limit of the preset high-end voltage interval is greater than the upper limit of the preset low-end voltage interval. The preset low-end voltage interval The lower limit value is greater than the upper limit value of the preset end voltage interval, and the upper limit value of the preset end voltage interval is called the preset end voltage threshold. The embodiments of this application do not limit the specific division of the preset high-end voltage interval, the preset low-end voltage interval, and the preset end voltage interval, which can be set according to needs in actual applications.

Since the minimum cell voltage is also larger when the battery SOC is higher, the integral value of the PID algorithm after multiple iterations

will continue to increase, causing the final calculated first allowable power P to also continue to increase, which may easily lead to the final power control failure. Therefore, the integral coefficient k _i needs to be adjusted small, so the target calculation coefficient in the preset high-end voltage interval or the preset high-end SOC interval is the integral coefficient k _i .

When the battery SOC is low, the minimum cell voltage is also small. If the proportion coefficient k _p is small, the final calculated first allowable power will also be small, thus limiting the power of the battery. Therefore, the proportional coefficient k _p needs to be increased in the preset low-end voltage interval or the preset low-end SOC interval. Therefore, the target calculation coefficient in the preset low-end voltage interval or the preset low-end SOC interval is the proportional coefficient k _p .

When the battery SOC is very low and the battery is about to run out of power, the integral coefficient k _i needs to be appropriately increased to make the overall control error converge. When the actual power follows the allowable power response, the minimum cell voltage will eventually be the same as the undervoltage. The thresholds are consistent. Therefore, the target calculation coefficient in the preset end voltage interval or the preset end SOC interval is the integral coefficient k _i .

The controller of the electrical equipment is pre-configured with the mapping relationship between the above-mentioned SOC interval or different voltage interval and the target calculation coefficient. For the current battery SOC, first determine the range to which the battery SOC belongs. If the battery SOC belongs to the preset high-end SOC range, or the minimum cell voltage belongs to the preset high-end voltage range, or the battery SOC is less than or equal to the preset end SOC threshold, Or, if the minimum cell voltage is less than or equal to the preset terminal voltage threshold, it is determined that the current target calculation coefficient that needs to be adjusted is the integral coefficient of the PID algorithm. If the battery SOC belongs to the preset low-end SOC range, or the minimum cell voltage belongs to the preset low-end voltage range, then it is determined that the target calculation coefficient that currently needs to be adjusted is the proportional coefficient of the PID algorithm.

Based on the impact of different calculation coefficients on the calculation results of the PID algorithm under different SOC intervals or different voltage intervals, the target calculation coefficients that need to be adjusted under different SOC intervals or different voltage intervals are determined. During the application process, the target calculation coefficient is determined based on the current battery SOC or minimum cell voltage. It is possible to determine the target calculation coefficient that needs to be adjusted based on the cell characteristics and improve the accuracy of calculation coefficient adjustment.

After determining the current target calculation coefficient that needs to be adjusted through the above method, obtain the target calculation coefficient corresponding to the battery SOC from the mapping relationship between the preset SOC interval and the target calculation coefficient; or, from the preset voltage interval and the target calculation coefficient In the mapping relationship, obtain the target calculation coefficient corresponding to the minimum cell voltage.

For the preset high-end SOC interval, the target calculation coefficient is an integral coefficient. In the mapping relationship between the preset SOC interval and the target calculation coefficient, the SOC interval includes multiple SOC intervals divided into the preset high-end SOC interval. Each SOC The intervals correspond to different values of the integral coefficient. The greater the SOC in the SOC interval, the smaller the value of the integral coefficient corresponding to the SOC interval. Similarly, for the preset high-end voltage interval, in the mapping relationship between the preset voltage interval and the target calculation coefficient, the voltage interval includes multiple voltage intervals divided into the preset high-end voltage interval, and each voltage interval corresponds to the integral For different values of the coefficient, the greater the voltage in the voltage range, the smaller the value of the integral coefficient corresponding to the voltage range.

For the preset low-end SOC interval, the target calculation coefficient is a proportional coefficient. In the mapping relationship between the preset SOC interval and the target calculation coefficient, the SOC interval includes multiple SOC intervals divided by the preset low-end SOC interval. , each SOC interval corresponds to a different value of the proportional coefficient. The smaller the SOC in the SOC interval, the greater the value of the proportional coefficient corresponding to the SOC interval. Similarly, for the preset low-end voltage interval, in the mapping relationship between the preset voltage interval and the target calculation coefficient, the voltage interval includes multiple voltage intervals divided into the preset low-end voltage interval, and each voltage interval corresponds to Due to different values of the proportional coefficient, the smaller the voltage in the voltage range, the greater the value of the proportional coefficient corresponding to the voltage range.

For the preset end SOC interval, the target calculation coefficient is an integral coefficient. In the mapping relationship between the preset SOC interval and the target calculation coefficient, the SOC interval includes multiple SOC intervals divided into the preset end SOC interval. Each SOC The intervals correspond to different values of the integral coefficient. The smaller the SOC in the SOC interval, the greater the value of the integral coefficient corresponding to the SOC interval. Similarly, for the preset end voltage interval, in the mapping relationship between the preset voltage interval and the target calculation coefficient, the voltage interval includes multiple voltage intervals divided into the preset end voltage interval, and each voltage interval corresponds to the integral For different values of the coefficient, the smaller the voltage in the voltage range, the greater the value of the integral coefficient corresponding to the voltage range.

Through the mapping relationship between the preset SOC interval and the value of the target calculation coefficient, or the mapping relationship between the preset voltage interval and the value of the target calculation coefficient, it can be based on the current battery SOC or the minimum cell voltage. The value of the corresponding target calculation coefficient is quickly obtained, which improves the efficiency of adjusting the target calculation coefficient.

In other embodiments, when the target calculation coefficient is an integral coefficient, the preset adjustment coefficient corresponding to the battery SOC or the minimum cell voltage can also be obtained, and the preset adjustment coefficient and the value are calculated in each iteration cycle of the PID algorithm. The product of the integration coefficient corresponding to the previous iteration cycle.

Among them, if the current battery SOC belongs to the preset high-end SOC range, or the minimum cell voltage belongs to the preset high-end voltage range, the preset adjustment coefficient is less than 1; if the current battery SOC is less than or equal to the preset end SOC threshold, or, If the minimum cell voltage is less than or equal to the preset terminal voltage threshold, the preset adjustment coefficient is greater than 1.

In the preset high-end SOC interval or the preset high-end voltage interval, the preset adjustment coefficient is less than 1, and the integral coefficient of each iteration is multiplied by the preset adjustment coefficient less than 1. As the number of iterations increases, the integral coefficient will continue to become smaller. In this way, when the battery SOC is high and the minimum cell voltage is also high, the integral value can be effectively avoided.

continuously increasing situation, avoid the final calculated first allowable power being too large, and ensure that subsequent power control will not fail. When the current battery SOC is less than or equal to the preset end SOC threshold, or the minimum cell voltage is less than or equal to the preset end voltage threshold, the preset adjustment coefficient is greater than 1, and the integral coefficient of each iteration is multiplied by the preset adjustment greater than 1. Coefficient, the integral coefficient will continue to increase as the number of iterations increases. In this way, when the battery is almost out of power, the overall control error can be converged. When the actual power follows the allowable power response, the minimum cell voltage can finally be consistent with the controlled undervoltage threshold.

After adjusting the target calculation coefficient in the above manner, the first allowable power of the battery is calculated through the PID algorithm based on the voltage error value, the cell impedance included in the electrical parameters, and the adjusted calculation coefficient. Then, based on the electrical parameters including cell temperature and battery SOC, the corresponding initial allowable power is obtained from the preset power map table. If the first allowed power is less than the initial allowed power, the battery is controlled to reduce the current actual power to the first allowed power.

Among them, the preset power map table is the allowable power corresponding to different cell temperatures and different battery SOC measured when the battery is in a static state. Obtain the current initial allowable power from the preset power map table. If the first allowable power is less than the initial allowable power, it means that the initial allowable power given in the preset power map table is too high. If you continue to use this In response to the initial allowable power, undervoltage will occur. Therefore, the first allowable power is used as the final allowable power, and the battery is controlled to reduce from the current actual power to the first allowable power, thereby effectively avoiding the undervoltage problem caused by the high initial allowable power. When the first allowable power is smaller than the initial allowable power as the intervention time of power control, the available capacity of the battery core can be maximized without under-voltage.

In other embodiments of the present application, the second allowable power of the battery is also estimated based on the electrical parameters of the battery. The allowable power of the battery is controlled in a closed loop according to the first allowable power, the second allowable power and the electrical parameters.

On the basis of the first allowable power calculated using the PID algorithm based on the voltage error value, the second allowable power is estimated based on the electrical parameters of the battery, and closed-loop control is performed based on the first allowable power and the second allowable power. Improves the accuracy of allowable power control and avoids undervoltage problems that may occur under any circumstances.

The estimation process of the second allowable power is to determine the undervoltage threshold corresponding to the cell temperature based on the cell temperature included in the electrical parameters, and calculate the difference between the minimum cell voltage included in the electrical parameters and the undervoltage threshold. , calculate the second allowable power of the battery based on the difference, the cell impedance included in the electrical parameters, and the current overall voltage of the battery.

Specifically, calculate the ratio of the difference between the minimum cell voltage and the undervoltage threshold (U _real -U _lim ) and the cell impedance R _all to obtain the allowable current of the cell.

Then calculate the product of the allowable current i _max and the current overall voltage V _pack of the battery to obtain the second allowable power of the battery, that is, the second allowable power P _max =V _pack *i _max /1000.

Among them, the cell impedance R _all can be calculated according to any of the methods mentioned in step 101. If the preset equivalent circuit model is used to simulate and calculate the cell impedance R _all and then estimate the second allowable power, the second allowable power is calculated based on the mechanical characteristics of the cell. It is necessary to ensure that the estimation error is within Within the acceptable range for engineering applications.

The second allowable power of the battery is estimated based on the electrical parameters of the battery, so that the estimated second allowable power is adapted to the cell characteristics of the battery, and the second allowable power is used in combination with the first allowable power dynamically calculated using the PID algorithm. The power is controlled in a closed loop, making the control of the allowable power more accurate and effectively avoiding undervoltage problems.

The process of using the first allowable power and the second allowable power for closed-loop control is to obtain the corresponding initial allowable power from the preset power map table according to the cell temperature and battery SOC included in the electrical parameters. Determine the minimum value of the first allowed power and the second allowed power. If the minimum value is less than the initial allowable power, the battery is controlled to reduce the current actual power to the minimum value.

Since the estimated second allowable power may have errors, and the first allowable power calculated using the PID algorithm may also have errors, the minimum value of the first allowable power and the second allowable power is used as the final allowable power. power, reducing the actual power of the battery to a minimum. This makes the control of the allowable power more precise and more accurate, and can avoid undervoltage problems that may occur under any working conditions and any cell status.

In some embodiments, if both the first allowed power and the second allowed power are less than the initial allowed power, the battery is controlled to reduce the current actual power to the second smallest of the first allowed power and the second allowed power. value, and then decrease from the second smallest value to the minimum value.

If the first allowable power and the second allowable power are both less than the initial allowable power, and the first allowable power is less than the second allowable power, the actual power of the battery is first controlled to be reduced to the second allowable power, and then the The second allowable power is reduced to the first allowable power. Or, if the first allowable power and the second allowable power are both less than the initial allowable power, and the first allowable power is greater than the second allowable power, the actual power of the battery is first controlled to be reduced to the first allowable power, and then Reduce from the first allowed power to the second allowed power.

In this way, it is first reduced to the second smallest value among the first allowable power and the second allowable power, and then reduced from the second smallest value to the minimum value. This adapts to the power reduction requirements of electrical equipment and can make the power change smoother and avoid Excessive instantaneous changes in power can lead to sudden changes in the operating status of electrical equipment, thus improving user experience.

In the embodiment of the present application, during the process of reducing power, the power of the battery can be controlled to be reduced according to a preset reduction rate. Among them, the preset reduction rate can be 4kw/s, 5kw/s or 8kw/s, etc. Reducing battery power according to a preset reduction rate can make the power reduction process smoother and avoid sudden changes in battery power.

In order to facilitate understanding of the power control process provided by the embodiments of the present application, description will be made below with reference to the accompanying drawings. As shown in Figure 2, the electrical equipment detects electrical parameters such as cell temperature, battery SOC, and minimum cell voltage. Based on the cell temperature and battery SOC, the BMS obtains the initial allowable power from the preset power map table. and calculating the voltage error value based on the minimum cell voltage and the undervoltage threshold, and calculating the first allowable power through the PID controller based on the voltage error value. And the power is estimated based on the electrical parameters to obtain the second allowable power. According to the initial allowed power, the first allowed power and the second allowed power, the final allowed power is output through post-processing. After the actual power of the controlled battery becomes the final allowable power, the electrical parameters detected by the electrical equipment will also change, and then power control is performed based on the changed electrical parameters. The entire power control process forms a closed loop. The power control process shown in FIG. 2 is only an example. In actual applications, the power control may also be a control process provided by other embodiments of the present application.

In the embodiment of the present application, the allowable power is adaptively controlled based on the electrical parameters, and the allowable power of the battery core is given based on the actual capacity of the battery core, so that the energy of the battery can be fully exerted and avoid arbitrary working conditions and arbitrary battery cells. When an under-voltage problem occurs, it can maximize the available power of the battery without under-voltage. For electric vehicles, emergency acceleration or deceleration at low temperatures, low SOC, abnormal aging of battery cells, etc., and undervoltage caused by sharp voltage drops caused by high current operating conditions, can be effectively avoided and ensure that the battery energy can be fully charged. play.

In order to more intuitively reflect the effects of the power control of the embodiments of the present application, a comparative analysis of the effects of related technologies and the effects of the embodiments of the present application will be performed below in conjunction with the accompanying drawings. As shown in the effect comparison chart in Figure 3, the curve numbered 1 in Figure 3 is the power curve corresponding to the embodiment of the present application, and the curve numbered 2 is the power curve corresponding to the related technology. The curve labeled 3 is the actual power curve of the electrical equipment. Figure 4 shows the voltage curve of the minimum cell voltage changing with time. The voltage values marked on the ordinate of Figure 4 are the undervoltage thresholds at different cell temperatures.

It can be seen from the power curve numbered 2 in Figure 3 that the related technology does not start power limitation until 1079s. At this time, the minimum cell voltage in Figure 4 has reached 2499mv, and the undervoltage threshold at this time is 2500mv. The minimum The cell voltage is already lower than the undervoltage threshold. It can be seen from the power curves labeled 2 and 3 in Figure 3 that during the power reduction process of related technologies, the actual power of the electrical equipment is still used close to the allowable power. Finally, the ultimate undervoltage occurs at 1083s, and the minimum power The core voltage reaches 913mv. It can be seen from the power curve numbered 1 in Figure 3 that the control scheme of the embodiment of the present application begins to identify the risk of undervoltage at 1075s, starts reducing power 4s earlier than related technologies, and enters the automatic power closed-loop feedback state. Adaptive adjustment control can effectively avoid this abnormal under-voltage scenario.

Comparing the effects of the present application and related technologies from the perspective of current, as shown in Figure 5, the curve labeled 4 is the actual working condition current curve of the electrical equipment, and the curve labeled 5 is the current curve corresponding to the embodiment of the present application. The curve labeled 6 is the current curve corresponding to the related technology. Figure 6 is an enlarged schematic diagram of the curve within the rectangular frame in Figure 5. It can be seen from Figure 6 that when power control intervenes, the actual operating current is 339A, and the allowable current of this application is 299A, which is 130A higher than the allowable current 169A controlled by the related technology. The duration is about 4s. The capacity is increased by about 77%. Therefore, the power control method of the embodiment of the present application can use electrical equipment to achieve better acceleration performance. By adaptively adjusting the power, the available power of the battery can be maximized without undervoltage.

An embodiment of the present application also provides a battery power control device, which is used to execute the battery power control method provided by the above embodiments. As shown in Figure 7, the device includes:

Parameter acquisition module 201 is used to acquire the electrical parameters of the battery in real time;

The power control module 202 is used to perform closed-loop control on the allowable power of the battery according to the electrical parameters.

The power control module 202 is used to calculate the voltage error value of the battery based on the minimum cell voltage included in the electrical parameters; based on the voltage error value, perform closed-loop control of the allowable power of the battery.

The power control module 202 is used to calculate the first allowable power of the battery through the PID algorithm based on the voltage error value and the electrical parameters; and perform closed-loop control on the allowable power of the battery based on the first allowable power and the electrical parameters.

The power control module 202 is used to adjust the calculation coefficient of the PID algorithm based on the electrical parameters; based on the voltage error value, the cell impedance included in the electrical parameters and the adjusted calculation coefficient, calculate the first allowable power of the battery through the PID algorithm .

The power control module 202 is configured to determine the target calculation coefficient that currently needs to be adjusted based on the battery SOC or the minimum cell voltage included in the electrical parameters; and adjust the target calculation coefficient based on the battery SOC or the minimum cell voltage.

The power control module 202 is used to control if the battery SOC belongs to the preset high-end SOC range, or the minimum cell voltage belongs to the preset high-end voltage range, or the battery SOC is less than or equal to the preset end SOC threshold, or the minimum cell voltage is less than or equal to If the terminal voltage threshold is preset, the current target calculation coefficient that needs to be adjusted is determined to be the integral coefficient of the PID algorithm; if the battery SOC belongs to the preset low-end SOC range, or the minimum cell voltage belongs to the preset low-end voltage range, then the current The target calculation coefficient that needs to be adjusted is the proportional coefficient of the PID algorithm.

The power control module 202 is configured to obtain the target calculation coefficient corresponding to the battery SOC from the preset mapping relationship between the SOC interval and the target calculation coefficient; or, from the mapping relationship between the preset voltage interval and the target calculation coefficient, obtain the minimum The target calculation coefficient corresponding to the cell voltage.

The power control module 202 is used to obtain the preset adjustment coefficient corresponding to the battery SOC or the minimum cell voltage if the target calculation coefficient is an integral coefficient, and calculate the preset adjustment coefficient and the previous iteration in each iteration cycle of the PID algorithm. The product of the integration coefficient corresponding to the period; among them, if the battery SOC belongs to the preset high-end SOC range, or the minimum cell voltage belongs to the preset high-end voltage range, the preset adjustment coefficient is less than 1; if the battery SOC is less than or equal to the preset end SOC The threshold, or the minimum cell voltage is less than or equal to the preset terminal voltage threshold, then the preset adjustment coefficient is greater than 1.

The power control module 202 is used to obtain the corresponding initial allowed power from the preset power map table according to the cell temperature and battery SOC included in the electrical parameters; if the first allowed power is less than the initial allowed power, control the battery Reduce the current actual power to the first allowed power.

The power control module 202 is configured to estimate the second allowed power of the battery based on the electrical parameters; and perform closed-loop control on the allowed power of the battery based on the first allowed power, the second allowed power and the electrical parameters.

The power control module 202 is configured to determine an undervoltage threshold corresponding to the cell temperature based on the cell temperature included in the electrical parameters; calculate the difference between the minimum cell voltage included in the electrical parameters and the undervoltage threshold; and based on the difference , the electrical parameters include the cell impedance and the current overall voltage of the battery, and the second allowable power of the battery is calculated.

The power control module 202 is configured to obtain the corresponding initial allowable power from the preset power map table according to the cell temperature and battery SOC included in the electrical parameters; determine the minimum of the first allowable power and the second allowable power. value; if the minimum value is less than the initial allowable power, the battery is controlled to reduce the current actual power to the minimum value.

The power control module 202 is used to control the battery to reduce the current actual power to the second of the first allowed power and the second allowed power if both the first allowed power and the second allowed power are less than the initial allowed power. small value, and then decrease from the second smallest value to the minimum value.

The power control module 202 is used to control the reduction of battery power at a preset reduction rate during the process of reducing battery power.

The power control module 202 is used to determine the undervoltage threshold corresponding to the cell temperature according to the cell temperature included in the electrical parameters; calculate the difference between the minimum cell voltage included in the electrical parameters and the undervoltage threshold to obtain the battery's voltage error value.

The electrical parameters include the cell impedance of the battery. The parameter acquisition module 201 simulates the current operating conditions of the battery through a preset equivalent circuit model to obtain the first-order high-frequency impedance, second-order low-frequency impedance and ohmic impedance corresponding to the battery; calculate the first-order The sum of high-frequency impedance, second-order low-frequency impedance and ohmic impedance is the cell impedance of the battery.

The electrical parameters include the cell impedance of the battery. The parameter acquisition module 201 calculates the cell impedance of the battery based on the current current of the battery included in the electrical parameters and the change in cell voltage under the current current; and obtains the preset value corresponding to the current current. Calibration impedance: perform a weighted sum of the preset calibration impedance and calculated cell impedance to obtain the final cell impedance.

The battery power control device provided by the above embodiments of the present application and the battery power control method provided by the embodiments of the present application are based on the same inventive concept, and have the same beneficial effects as the methods adopted, run or implemented by the applications stored therein.

Figure 8 shows a schematic block diagram of an electronic device 700 according to an embodiment of the present application. The electronic device may be a BMS, a VCU, a domain controller, etc. As shown in Figure 8, the electronic device 700 includes a processor 710. Optionally, the electronic device 700 also includes a memory 720, where the memory 720 is used to store a computer program, and the processor 710 is used to read the computer program and execute it based on the computer program. The aforementioned battery power control methods in various embodiments of the present application.

An embodiment of the present application also provides an electrical device, which includes the above-mentioned electronic device. The electrical device can be an electric vehicle, an electric aircraft, an electric toy, etc.

Embodiments of the present application also provide a computer-readable storage medium for storing a computer program. When the computer program is executed by a processor, the methods of the various embodiments of the present application are implemented.

Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each specific application, but such implementations should not be considered beyond the scope of this application.

Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, devices and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be described again here.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or can be integrated into another system, or some features can be ignored, or not implemented. On the other hand, the coupling or direct coupling or communication connection between each other shown or discussed may be through some interfaces, and the indirect coupling or communication connection of the devices or units may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or they may be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present application can be integrated into one processing unit, each unit can exist physically alone, or two or more units can be integrated into one unit.

If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application essentially or the part that contributes to the existing technology 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 and includes a number of instructions. It is used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program code. .

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application. should be covered by the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

A battery power control method, characterized by including:

Obtain the electrical parameters of the battery in real time;

According to the electrical parameters, the allowable power of the battery is controlled in a closed loop.
The method according to claim 1, characterized in that performing closed-loop control on the allowable power of the battery according to the electrical parameters includes:

Calculate the voltage error value of the battery according to the minimum cell voltage included in the electrical parameters;

Based on the voltage error value, the allowable power of the battery is controlled in a closed loop.
The method of claim 2, wherein performing closed-loop control on the allowable power of the battery based on the voltage error value includes:

Based on the voltage error value and the electrical parameters, calculate the first allowable power of the battery through a PID algorithm;

Close-loop control is performed on the allowable power of the battery according to the first allowable power and the electrical parameters.
The method of claim 3, wherein calculating the first allowable power of the battery through a PID algorithm based on the voltage error value and the electrical parameters includes:

Based on the electrical parameters, adjust the calculation coefficient of the PID algorithm;

Based on the voltage error value, the cell impedance included in the electrical parameters, and the adjusted calculation coefficient, the first allowable power of the battery is calculated through the PID algorithm.
The method of claim 4, wherein adjusting the calculation coefficient of the PID algorithm based on the electrical parameters includes:

Based on the battery SOC or minimum cell voltage included in the electrical parameters, determine the target calculation coefficient that currently needs to be adjusted;

The target calculation coefficient is adjusted based on the battery SOC or the minimum cell voltage.
The method according to claim 5, characterized in that, based on the battery SOC or the minimum cell voltage included in the electrical parameters, determining the target calculation coefficient that currently needs to be adjusted includes:

If the battery SOC belongs to the preset high-end SOC range, or the minimum cell voltage belongs to the preset high-end voltage range, or the battery SOC is less than or equal to the preset end SOC threshold, or the minimum cell voltage is less than is equal to the preset terminal voltage threshold, then it is determined that the current target calculation coefficient that needs to be adjusted is the integral coefficient of the PID algorithm;

If the battery SOC belongs to the preset low-end SOC range, or the minimum cell voltage belongs to the preset low-end voltage range, then it is determined that the target calculation coefficient that currently needs to be adjusted is the proportional coefficient of the PID algorithm.
The method of claim 6, wherein adjusting the target calculation coefficient based on the battery SOC or minimum cell voltage includes:

Obtain the target calculation coefficient corresponding to the battery SOC from the mapping relationship between the preset SOC interval and the target calculation coefficient; or,

The target calculation coefficient corresponding to the minimum cell voltage is obtained from the mapping relationship between the preset voltage interval and the target calculation coefficient.
The method of claim 6, wherein adjusting the target calculation coefficient based on the battery SOC or minimum cell voltage includes:

If the target calculation coefficient is the integral coefficient, obtain the preset adjustment coefficient corresponding to the battery SOC or the minimum cell voltage, and calculate the preset adjustment in each iteration cycle of the PID algorithm. The product of the coefficient and the integration coefficient corresponding to the previous iteration cycle;

Among them, if the battery SOC belongs to the preset high-end SOC range, or the minimum cell voltage belongs to the preset high-end voltage range, then the preset adjustment coefficient is less than 1; if the battery SOC is less than or equal to the preset terminal SOC threshold, Or, if the minimum cell voltage is less than or equal to the preset terminal voltage threshold, then the preset adjustment coefficient is greater than 1.
The method according to claim 3, characterized in that performing closed-loop control on the allowable power of the battery according to the first allowable power and the electrical parameters includes:

According to the cell temperature and battery SOC included in the electrical parameters, obtain the corresponding initial allowable power from the preset power map table;

If the first allowed power is less than the initial allowed power, the battery is controlled to reduce the current actual power to the first allowed power.
The method according to claim 3, characterized in that performing closed-loop control on the allowable power of the battery according to the first allowable power and the electrical parameters includes:

Based on the electrical parameters, estimate a second allowable power of the battery;

Close-loop control is performed on the allowed power of the battery according to the first allowed power, the second allowed power and the electrical parameters.
The method of claim 10, wherein estimating the second allowable power of the battery based on the electrical parameters includes:

Based on the battery core temperature included in the electrical parameter, determine the undervoltage threshold corresponding to the battery core temperature;

Calculate the difference between the minimum cell voltage included in the electrical parameters and the undervoltage threshold;

The second allowable power of the battery is calculated based on the difference, the cell impedance included in the electrical parameter, and the current overall voltage of the battery.
The method according to claim 10, characterized in that the allowed power of the battery is closed-loop based on the first allowed power, the second allowed power and the electrical parameters. Controls, including:

According to the cell temperature and battery SOC included in the electrical parameters, obtain the corresponding initial allowable power from the preset power map table;

Determine the minimum value of the first allowed power and the second allowed power;

If the minimum value is less than the initial allowed power, the battery is controlled to reduce the current actual power to the minimum value.
The method of claim 12, wherein the controlling the battery to reduce the current actual power to the minimum value includes:

If both the first allowed power and the second allowed power are less than the initial allowed power, the battery is controlled to reduce from the current actual power to the first allowed power and the second allowed power. Use the second smallest value in power, and then reduce it from the second smallest value to the minimum value.
The method according to any one of claims 9-13, characterized in that the method further includes:

In the process of reducing the battery power, the battery power is controlled to be reduced at a preset reduction rate.
The method of claim 2, wherein calculating the voltage error value of the battery based on the minimum cell voltage included in the electrical parameters includes:

According to the battery core temperature included in the electrical parameter, determine the undervoltage threshold corresponding to the battery core temperature;

Calculate the difference between the minimum cell voltage included in the electrical parameters and the undervoltage threshold to obtain the voltage error value of the battery.
The method according to any one of claims 1-13 and 15, wherein the electrical parameter includes the cell impedance of the battery, and obtaining the cell impedance of the battery includes:

Simulate the current operating conditions of the battery through a preset equivalent circuit model to obtain the corresponding first-order high-frequency impedance, second-order low-frequency impedance and ohmic impedance of the battery;

Calculate the sum of the first-order high-frequency impedance, the second-order low-frequency impedance and the ohmic impedance to obtain the cell impedance of the battery.
The method according to any one of claims 1-13 and 15, wherein the electrical parameter includes the cell impedance of the battery, and obtaining the cell impedance of the battery includes:

Calculate the cell impedance of the battery according to the current current of the battery included in the electrical parameters and the change in cell voltage under the current current;

Obtain the preset calibration impedance corresponding to the current current, perform a weighted sum of the preset calibration impedance and the calculated cell impedance, and obtain the final cell impedance.
A battery power control device, characterized by including:

Parameter acquisition module, used to obtain the electrical parameters of the battery in real time;

A power control module, configured to perform closed-loop control on the allowable power of the battery according to the electrical parameters.
An electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that when the processor executes the computer program, it implements claim 1 -The method described in any one of 17.
An electrical device, characterized by comprising the electronic device according to claim 19.
A computer-readable storage medium stores a computer program, and is characterized in that when the computer program is executed by a processor, the method according to any one of claims 1-17 is implemented.