Equalization method of energy storage battery management system

Abstract

The invention discloses an equalization method of an energy storage battery management system, which belongs to the energy storage battery management system, and comprises the following steps: S1, collecting data of each group of single batteries and each group of series battery packs; s2, analyzing and evaluating the collected data of each group of single batteries and each group of series battery packs; s3, analyzing and evaluating the working conditions of each group of single batteries and each group of series battery packs; s4, judging whether the acquired numerical value between each group of single batteries and each group of series battery packs is lower than or higher than a preset threshold value or not; when the number of the batteries and the battery packs needs to be equalized is large, an active equalization mode is used for equalization, so that the equalization speed of the batteries and the battery packs is increased, heat generated when the batteries and the battery packs are equalized is reduced, and the equalization stability of the energy storage batteries is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage battery management systems, and in particular relates to an equalization method for an energy storage battery management system. Background Art

[0002] The balancing technology in the energy storage battery management system is designed to ensure that the voltage and charge state of each single cell in the battery pack are consistent, thereby improving the service life and performance of the entire battery pack. The balancing methods mainly include passive balancing and active balancing. However, in the process of battery balancing, a single balancing method may not be able to effectively balance the energy storage battery, which may lead to problems such as increased battery temperature, slow balancing speed and complex structure. For this reason, we propose a balancing method for an energy storage battery management system. Summary of the invention

[0003] The present invention provides a balancing method for an energy storage battery management system to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a balancing method for an energy storage battery management system, comprising the following steps: S1, collecting data of each group of single batteries and each group of series-connected batteries; S2, analyzing and evaluating the data collected from each group of single batteries and each group of series-connected batteries; S3, analyzing and evaluating the working conditions of each group of single batteries and each group of series-connected batteries; S4, determining whether the values ​​collected between the groups of single batteries and the groups of series-connected batteries are lower or higher than a preset threshold; S5. When it is determined that the values ​​between the groups of single batteries and the groups of series-connected batteries are lower or higher than a preset threshold, active balancing and passive balancing are used for balancing according to the difference and the amount of difference.

[0005] Furthermore, in step S1, the collected data include voltage, capacitance, current, resistance, battery temperature, SOC and SOH.

[0006] Furthermore, the collection frequency in step S1 is once every 1 to 5 seconds.

[0007] Furthermore, in step S2, when performing data analysis and evaluation, data that is obviously deviated from the normal range and is generated by a temporary sensor failure or electromagnetic interference is removed.

[0008] Furthermore, in step S2, a multi-dimensional evaluation index system is established, such as a voltage consistency index, and the status of the battery and the battery pack can be comprehensively evaluated based on the current distribution uniformity and temperature balance.

[0009] Further, in step S4; The threshold of the charge cut-off voltage is set at around 4.2V; The discharge cut-off voltage threshold is set between 2.5 and 3.0V; The current threshold is ±20% of the rated current; The high temperature threshold during charging is set at 50-60°C; The low temperature threshold during charging is set to 0-5°C; The high temperature threshold during discharge is set at 60-70°C; The low temperature threshold during discharge is set to -20 to -10°C.

[0010] Furthermore, in step S5, when the difference between the values ​​of a single battery and a battery group is small, passive balancing is performed; when the difference between the values ​​of a single battery and a battery group is large, active balancing is performed.

[0011] The beneficial effects of the present invention are: This method combines active balancing and passive balancing, and the two balancing methods are used alternately. When the number of batteries or battery groups that need to be balanced is small, the passive balancing method is used to balance the batteries and battery groups. When the number of batteries and battery groups that need to be balanced is large, the active balancing method is used to balance them, thereby increasing the balancing speed of batteries and battery groups, reducing the heat generated when the batteries and battery groups are balanced, and increasing the balancing stability of the energy storage battery. DETAILED DESCRIPTION

[0012] In order to further understand the content, features and effects of the present invention, the following embodiments are given to explain in detail.

[0013] Example: A method for balancing an energy storage battery management system comprises the following steps; S1. Collect data of each single battery group and each series battery group. The collected data include voltage, capacitance, current, resistance, battery temperature, SOC and SOH. Voltage data can reflect the battery's charge state and charge and discharge degree; capacitance data is helpful to analyze the battery's energy storage capacity; current data reflects the battery's charge and discharge rate; resistance data is related to the battery's internal resistance and can be used to judge the battery's health; battery temperature data is a key factor in ensuring battery safety and stable performance; SOC (state of charge) can intuitively indicate the proportion of the battery's remaining power; SOH (state of health) comprehensively reflects the battery's performance degradation degree. The acquisition frequency in step S1 is once every 1 to 5 seconds, and when the battery is in high-power charging and discharging, the chemical reaction inside the battery is more intense and the state changes rapidly. Therefore, when performing high-power charging and discharging, the acquisition frequency needs to be increased to multiple times per second in order to capture possible abnormal data changes in time. At the same time, it is necessary to collect data such as the overall voltage and current of the battery group and the charge and discharge power of the battery group. When collecting data, the accuracy of the voltage sensor needs to reach ±0.01V, the accuracy of the current sensor needs to reach ±0.05A, and the accuracy of the temperature sensor needs to reach ±0.5℃. The voltage sensor has an accuracy of ±0.01V and can accurately measure the voltage of the battery, which is very useful for determining whether the battery has reached the charge cut-off voltage (about 4.2V) or the discharge cut-off voltage (between 2.5 and 3.0V). The current sensor has an accuracy of ±0.05A and can accurately monitor the charge and discharge current of the battery to ensure that it is within the range of ±20% of the rated current, preventing damage to the battery caused by overcharge and over-discharge current. The temperature sensor has an accuracy of ±0.5℃ and can promptly detect whether the battery exceeds the high temperature threshold (50-60℃) and low temperature threshold (0-5℃) during charging, as well as the high temperature threshold (60-70℃) and low temperature threshold (-20--10℃) during discharging, thereby ensuring that the battery operates within an appropriate temperature range. S2. Analyze and evaluate the data collected from each group of single batteries and each group of series-connected batteries. When analyzing and evaluating the data, remove the data that is obviously deviated from the normal range due to sensor short circuit failure or electromagnetic interference. Statistical methods such as the 3σ principle (in a normal distribution, the probability that the data falls within the interval (μ - 3σ, μ + 3σ) is 99.7%, where μ is the mean and σ is the standard deviation. Data outside this range is considered an outlier) to identify and remove outliers; A multi-dimensional evaluation index system is established, such as voltage consistency index, and the status of batteries and battery packs can be comprehensively evaluated based on the uniformity of current distribution and temperature balance; S3. Analyze and evaluate the working conditions of each group of single batteries and each group of series-connected batteries. Evaluation of the working condition of a single battery: Evaluate the health of a single battery based on the collected and analyzed data. If the voltage change of a single battery is abnormal (such as the voltage rises too fast during charging, exceeding the normal charging voltage rise rate), it may indicate a short circuit or polarization inside the battery. By comparing the changes in the internal resistance of the battery, if the internal resistance gradually increases, it may indicate a loss of active material in the battery or a thickening of the film layer on the electrode surface, affecting the performance of the battery; Evaluation of the working condition of series battery packs: For series battery packs, focus on evaluating the overall performance of the battery pack and the coordinated operation of the batteries in the pack. When the overall voltage of the battery pack drops faster than normal, there may be a problem with one or more batteries in the pack. Analyze the SOC differences of the batteries in the battery pack. If the SOC difference is too large (for example, more than 10%), it will cause the energy utilization of the battery pack to decrease during the charging and discharging process, and may accelerate the aging of some batteries; S4, judging whether the values ​​collected between the groups of single batteries and the groups of series-connected batteries are lower or higher than a preset threshold, and the threshold is set at, The threshold of the charge cut-off voltage is set at around 4.2V; The discharge cut-off voltage threshold is set between 2.5 and 3.0V; The current threshold is ±20% of the rated current; The high temperature threshold during charging is set at 50-60°C; The low temperature threshold during charging is set to 0-5°C; The high temperature threshold during discharge is set at 60-70°C; The low temperature threshold during discharge is set to -20 to -10°C; During the battery charging and discharging process, the collected and analyzed data needs to be compared with the preset threshold in real time; S5. When it is determined that the values ​​between the groups of single batteries and the groups of series-connected batteries are lower or higher than a preset threshold, active balancing and passive balancing are used for balancing according to the difference and the amount of difference.

[0014] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A balancing method for an energy storage battery management system, characterized in that: The following steps are involved: S1, collecting data of each group of single batteries and each group of series-connected batteries; S2, analyzing and evaluating the data collected from each group of single batteries and each group of series-connected batteries; S3, analyzing and evaluating the working conditions of each group of single batteries and each group of series-connected batteries; S4, determining whether the values ​​collected between the groups of single batteries and the groups of series-connected batteries are lower or higher than a preset threshold; S5. When it is determined that the values ​​between the groups of single batteries and the groups of series-connected batteries are lower or higher than a preset threshold, active balancing and passive balancing are used for balancing according to the difference and the amount of difference.

2. The equalization method of an energy storage battery management system according to claim 1, characterized in that: In step S1, the collected data include voltage, capacitance, current, resistance, battery temperature, SOC and SOH.

3. The equalization method of an energy storage battery management system according to claim 1, characterized in that: The acquisition frequency in step S1 is once every 1 to 5 seconds.

4. The equalization method of an energy storage battery management system according to claim 1, characterized in that: In step S2, when performing data analysis and evaluation, data that is significantly deviated from the normal range and is caused by a temporary sensor failure or electromagnetic interference is removed.

5. The equalization method of an energy storage battery management system according to claim 1, characterized in that: In step S2, a multi-dimensional evaluation index system is established.

6. The equalization method of an energy storage battery management system according to claim 1, characterized in that: In the step S4; The threshold of the charge cut-off voltage is set at around 4.2V; The discharge cut-off voltage threshold is set between 2.5 and 3.0V; The current threshold is ±20% of the rated current; The high temperature threshold during charging is set at 50-60°C; The low temperature threshold during charging is set to 0-5°C; The high temperature threshold during discharge is set at 60-70°C; The low temperature threshold during discharge is set to -20 to -10°C.

7. The equalization method of an energy storage battery management system according to claim 1, characterized in that: In step S5, when the difference between the values ​​of a single battery and a battery group is small, passive balancing is performed; when the difference between the values ​​of a single battery and a battery group is large, active balancing is performed.