Bidirectional DC-DC bridge type active equalization energy re-storage system

Abstract

The invention discloses a bidirectional DC-DC bridge type active equalization energy re-storage system, which relates to the technical field of electric energy regulation and control, is used for improving the problem of insufficient power supply of a corresponding area when electric energy storage is not uniform, and comprises the steps of starting an MCU (Microprogrammed Control Unit) for self-inspection, confirming the state of a relay, detecting the energy of a battery cell, and sending an instruction to the MCU according to the energy of the battery cell. The MCU controls the relay to select a charging mode or a discharging mode to work, state information of the battery cells is collected through the MCU, a battery cell electric energy evaluation threshold value is set through a logistic regression algorithm to conduct energy classification on the battery cells, energy transfer operation is conducted according to the energy classification of the battery cells, state information of each battery cell is monitored in real time, SOC data are recorded, and the SOC data are stored in the battery cells. The equalization electric quantity is calculated according to the SOC data, the energy difference value between the battery cells is obtained, the equalization current is set to evaluate and calculate the equalization time, finally, the timer is used for performing time control on the equalization process, and electric energy storage is performed after a protection mechanism is set.

Description

Technical Field

[0001] The present invention relates to the technical field of electric energy regulation, and more specifically, to a bidirectional DC-DC bridge-type active equalization and re-storage system. Background Art

[0002] Electric energy regulation technology manages and controls the generation, transmission, distribution, and consumption of electric energy through a series of methods and devices. When applied to a bidirectional DC-DC bridge-type energy storage system, it can improve the energy storage efficiency and reduce the energy storage cost.

[0003] The prior art has the following deficiencies:

[0004] In the past, in a bidirectional DC-DC bridge-type energy storage system, no electric energy equalization was performed or passive equalization was carried out. After the electric energy was stored, the electric energy was detected. When abnormal storage was found, passive equalization was performed. When the electric energy storage was uneven and electricity was urgently needed in the corresponding area, it would lead to a problem of insufficient supply, causing delays in the corresponding engineering projects and increasing the time cost of the engineering projects. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a bidirectional DC-DC bridge-type active equalization and re-storage system, which classifies the electric energy of the battery cells in different battery packs by analyzing the electric energy conditions of the battery cells, and then stores the electric energy after equalizing it through an energy transfer mechanism to solve the problems proposed in the above background art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A bidirectional DC-DC bridge-type active equalization and re-storage system includes a system self-checking module, a charge and discharge control module, an equalization regulation module, and an estimation and update module;

[0008] The system self-checking module is used to start the MCU for self-checking, confirm the status of the relay, and ensure the normal operation of each module;

[0009] The charge and discharge control module detects the energy of the battery cells, sends instructions to the MCU according to the energy of the battery cells, and the MCU controls the relay to select different working modes;

[0010] The equalization regulation module collects the status information of the battery cells through the MCU, classifies the energy of the battery cells, transfers the energy according to the energy classification of the battery cells, and records the status information of each battery cell in real time and transmits the SOC data to the estimation and update module;

[0011] The estimation and update module calculates the equalization power according to the SOC data, obtains the energy difference between the battery cells, sets the equalization current to evaluate and calculate the equalization time, and sets a timer to control the time of the equalization process.

[0012] In a preferred embodiment, the MCU is an integrated circuit that includes a processor core, memory, and peripheral interfaces, and is used to control the relay to select the working mode and collect the state information of the battery cells; the SOC data represents the current battery charge level, expressed as a percentage, which refers to the ratio of the current stored energy of the battery to its maximum storage capacity.

[0013] In a preferred embodiment, the system self-check module is used to start the MCU for self-check. When starting the MCU, all circuit components inside the MCU are detected. A detection current is applied, and the current passing through each circuit component inside the MCU is detected. When the current is within the preset normal current threshold, the MCU is started and the current working state of the relay is determined.

[0014] In a preferred embodiment, the charge and discharge control module detects the energy of the battery cells and sends instructions to the MCU according to the cell energy. The MCU controls the relay to select the charging mode or the discharging mode. When controlling the relay to select the working mode, the bidirectional DC-DC bridge method is adopted. Among them, the bidirectional power module is powered by a DC power supply, and the MCU S32K1118 on the active equalization board controls the on and off of the relay;

[0015] When the charging mode is selected, the MUC controls the relay to open, and the bidirectional power module works in the forward mode. The bidirectional power module transfers the electrical energy of the DC power supply to the battery cells;

[0016] When the discharging mode is selected, the MCU controls the relay to open, and the bidirectional power module works in the reverse mode. The bidirectional power module transfers the electrical energy on the battery cells to the DC power supply;

[0017] The bidirectional power module is used to switch between charging and discharging. The MCU S32K1118 is a microcontroller used to control the on and off of the relay.

[0018] In a preferred embodiment, the state information of the battery cells in the equalization control module is the electrical energy of the battery cells and the charge and discharge rates of each battery cell in the working state. The charge and discharge rate is the average value of the charging rate of the battery cell in the charging mode and the discharging rate in the discharging mode. The electrical energy evaluation threshold of the battery cell is calculated using the logistic regression algorithm by integrating the electrical energy and charge and discharge rates of each battery cell.

[0019] In a preferred embodiment, the equalization control module calculates the electrical energy evaluation threshold of the battery cells using the logistic regression algorithm. The specific steps are as follows:

[0020] Normalize the electrical energy and charge and discharge rates of all battery cells in the equalization control module using the Max-Min normalization algorithm: x nore = x - x min / x max -x min , where x is the electrical energy or charge / discharge rate of each battery cell, and x min is the minimum value among the electrical energies or charge / discharge rates of all battery cells, and x max is the maximum value among the electrical energies or charge / discharge rates of all battery cells, and x nore is the result after standardizing the electrical energy or charge / discharge rate of the corresponding battery cell;

[0021] Calculate the logistic regression result through the logistic regression formula using the results after standardizing the electrical energy and charge / discharge rate of each battery cell: L = 1 / (1 + e -z ), where L is the logistic regression result calculated for each battery cell, e is the natural base, z is the logistic regression parameter and z is the sum of the results after standardizing the electrical energy and charge / discharge rate of each battery cell; Take the average of the logistic regression results calculated for each battery cell as the battery cell electrical energy evaluation threshold.

[0022] In a preferred embodiment, for each battery cell or battery pack pack, calculate the logistic regression result of the battery cell or battery pack pack and compare it with the battery cell electrical energy evaluation threshold. When the logistic regression result of the battery cell or battery pack pack exceeds the battery cell electrical energy evaluation threshold, it is determined that the electrical energy of the battery cell or battery pack pack is high; otherwise, it is determined that the electrical energy of the battery cell or battery pack pack is low;

[0023] The battery pack pack is a battery combination composed of multiple battery cells. When calculating the logistic regression result, calculate the average of the logistic regression results of each battery cell in the battery pack pack as the logistic regression result of the battery pack pack.

[0024] In a preferred embodiment, after the equalization control module classifies the energy of the battery cells, sort the battery cells according to the electrical energy size, select k battery cells from largest to smallest and mark them as transfer battery cells, and then select the corresponding number of battery cells from smallest to largest and mark them as receiving battery cells;

[0025] Randomly select one battery cell from the transfer battery cells and the receiving battery cells respectively, and randomly transfer the energy from the battery cell with high electrical energy to the battery cell with low electrical energy;

[0026] When performing energy transfer, turn on the relay corresponding to the battery cell with high electrical energy through the MCU and control the power module in the corresponding battery pack pack to be in the reverse mode, turn on the relay corresponding to the battery cell with low electrical energy through the MCU and control the power module in the corresponding battery pack pack to be in the forward mode, and transfer the electrical energy in the battery cell with high electrical energy to the battery cell with low electrical energy.

[0027] In a preferred embodiment, the main controller in the estimation and update module automatically calculates the balanced power value based on the SOC data of the corresponding battery cell, and takes the ratio of the power value to the preset balancing current as the balancing time, denoted as t. The main controller uses the balancing time t as the time for the battery cell to transfer energy.

[0028] Set a protection mechanism. If the overall SOC data of the current battery cluster is lower than that of other battery clusters, and the average voltage of the current battery cluster is lower than that of other battery clusters and lower than the preset minimum battery voltage threshold, then the current battery cluster does not enter the discharge mode.

[0029] If the overall SOC data of the current battery cluster is higher than that of other battery clusters, and the average voltage of the current battery cluster is higher than that of other battery clusters and higher than the preset maximum battery voltage threshold, then the current battery cluster does not enter the charging mode, and energy transfer is performed between the current battery cluster and the battery cluster with the minimum SOC data among other battery clusters.

[0030] The technical effects and advantages of a two-way DC-DC bridge-type active equalization and re-energy storage system of the present invention:

[0031] The present invention starts the MCU for self-check, confirms the relay state, detects the energy of the battery cell, sends instructions to the MCU according to the energy of the battery cell, the MCU controls the relay to select the charging or discharging mode to work, collects the state information of the battery cell through the MCU, classifies the energy of the battery cell, determines the transfer direction for energy transfer by energy classification, reduces the transfer cost, performs energy transfer operations according to the energy classification of the battery cell, monitors the state information of each battery cell in real time and records the SOC data, calculates the balanced power according to the SOC data and obtains the energy difference between the battery cells, sets the balancing current to evaluate and calculate the balancing time, and finally uses a timer to control the time of the balancing process, thereby improving the balancing efficiency and reducing the energy storage risk. Brief Description of the Drawings

[0032] Figure 1 It is a flowchart of a two-way DC-DC bridge-type active equalization and re-energy storage system of the present invention. Detailed Embodiment

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] The present invention performs self-check by starting the MCU, confirms the status of the relay, detects the energy of the battery cells, sends instructions to the MCU according to the energy of the battery cells, the MCU controls the relay to select the charging or discharging mode to work, collects the status information of the battery cells through the MCU, classifies the energy of the battery cells, performs energy transfer according to the energy classification of the battery cells, monitors the status information of each battery cell in real time and records the SOC data, calculates the equalization power according to the SOC data and obtains the energy difference between the battery cells, sets the equalization current to evaluate and calculate the equalization time, and finally uses a timer to control the time of the equalization process, so as to improve the equalization efficiency and reduce the energy storage risk.

[0035] Embodiment, a two-way DC-DC bridge-type active equalization and energy storage system, as Figure 1 shown, includes a system self-check module, a charge and discharge control module, an equalization control module and an estimation and update module, and the signals of each module are connected;

[0036] The functions of each module are as follows:

[0037] The system self-check module is used to start the MCU for self-check, confirm the status of the relay, and ensure the normal operation of each module;

[0038] The charge and discharge control module detects the energy of the battery cells, sends instructions to the MCU according to the energy of the battery cells, and the MCU controls the relay to select different working modes;

[0039] The equalization control module collects the status information of the battery cells through the MCU, classifies the energy of the battery cells, performs energy transfer according to the energy classification of the battery cells, monitors the status information of each battery cell in real time and records the SOC data and then transmits it to the estimation and update module;

[0040] The estimation and update module calculates the equalization power according to the SOC data and obtains the energy difference between the battery cells, sets the equalization current to evaluate and calculate the equalization time, and sets a timer to control the time of the equalization process.

[0041] It should be noted that the MCU is an integrated circuit, including a processor core, memory and peripheral interfaces, and is used to control the functions and operations of electronic devices. In this example, the MCU is used to control the relay to select the working mode and collect the status information of the battery cells; the SOC data represents the current power level of the battery, expressed as a percentage, which refers to the ratio of the energy currently stored in the battery to its maximum storage capacity.

[0042] One or more of the four sets of devices, namely the master control, main control, slave control and active equalization board, are used for processing in each of the above modules;

[0043] The master control device is used for centralized management of the battery stack, data aggregation and communication, to improve system efficiency. By means of centralized management and optimization strategies, it enhances the efficiency and safety of the entire energy storage system and has the following functions:

[0044] Function 1: Collect and aggregate battery data and communicate with external systems to ensure accurate information transmission and coordinated operation of the system;

[0045] Function 2: Implement subsequent charge and discharge strategies and balancing management strategies to ensure the efficient operation, safety and stability of the battery stack;

[0046] Function 3: System protection. When battery anomalies are detected, handle fault alarms to protect the battery system from damage.

[0047] It should be noted that the battery data includes the battery's power and charge / discharge power. The charge / discharge strategies and the balancing management strategies are respectively the processing methods for the battery's charge / discharge and energy balancing by subsequent modules.

[0048] The master control device is used for energy management, real-time monitoring of the energy state of the energy storage system, including battery power and charge / discharge power; coordinating different energy storage devices to enable them to work in coordination within the system.

[0049] The slave control device is used for data acquisition and data processing. It collects abnormal data of individual batteries and performs advanced control. The abnormal data of individual batteries are overvoltage, undervoltage and overtemperature. Advanced control means that when the detected pressure and temperature of the individual battery are lower or higher than the preset excessive threshold, it is determined that the battery is abnormal and an alarm message is sent to the BCU.

[0050] The active balancing board is used to achieve energy transfer between battery cells. The active balancing board includes an MCU, a bidirectional DC power module and a relay. The MCU is used to control the bidirectional DC power module and the relay, including CAN communication. Through CAN communication, information interaction with the master control is realized, and the charge / discharge mode is controlled by receiving the control instructions from the master control.

[0051] The system self-check module is used to start the MCU for self-check. When starting the MCU, all circuit components inside the MCU are detected. A detection current is applied, and the current passing through each circuit component inside the MCU is detected. When the current is within the preset normal current threshold, the MCU is started and the current working state of the relay is determined. It should be explained that the relay is an electrical switch, and the MCU controls the on / off state of the circuit through electromagnetic principles.

[0052] The charge and discharge control module detects the energy of the battery cells, sends instructions to the MCU according to the energy of the battery cells, and the MCU controls the relay to select the charging mode or the discharging mode. When controlling the relay to select the working mode, the bidirectional DC-DC bridge method is adopted. Among them, the bidirectional power module is powered by a DC power supply, and the on-off of the relay is controlled by the MCU S32K1118 on the active equalization board;

[0053] When the charging mode is selected, the MUC controls the relay to open, and the bidirectional power module works in the forward mode. The bidirectional power module transfers the electrical energy of the DC power supply into the battery cell;

[0054] When the discharging mode is selected, the MCU controls the relay to open, and the bidirectional power module works in the reverse mode. The bidirectional power module transfers the electrical energy on the battery cell into the DC power supply.

[0055] It should be noted that the bidirectional power module is a power management device that can transfer energy in two directions. It is used in the battery charge and discharge system and switches between charging and discharging. The MCU S32K1118 is a microcontroller, which is used to control the on-off of the relay in this example.

[0056] The state information of the battery cells in the equalization control module is the electrical energy of the battery cells and the charge and discharge rates of each battery cell in the working state. The charge and discharge rate is the average value of the charging rate of the battery cell in the charging mode and the discharging rate in the discharging mode. The electrical energy evaluation threshold of the battery cell is calculated by using the logistic regression algorithm based on the electrical energy and charge and discharge rates of each battery cell. The specific steps are as follows:

[0057] Normalize the electrical energy and charge and discharge rates of all battery cells in the equalization control module by using the Max-Min normalization algorithm: x nore =x - x min / x max - x min , where x is the electrical energy or charge and discharge rate of each battery cell, x min is the minimum value of the electrical energy or charge and discharge rates of all battery cells, x max is the maximum value of the electrical energy or charge and discharge rates of all battery cells, and x nore is the result after normalizing the electrical energy or charge and discharge rate of the corresponding battery cell;

[0058] Calculate the logistic regression result through the logistic regression formula for the results after normalizing the electrical energy and charge and discharge rates of each battery cell: L = 1 / (1 + e -z ), where L is the logistic regression result calculated for each battery cell, e is the natural base, z is the logistic regression parameter and z is the sum of the results after normalizing the electrical energy and charge and discharge rates of each battery cell; Take the average value of the logistic regression results calculated for each battery cell as the electrical energy evaluation threshold of the battery cell.

[0059] For each battery cell or battery pack (pack), calculate the logistic regression result of the battery cell or battery pack (pack) and compare it with the battery cell energy evaluation threshold. When the logistic regression result of the battery cell or battery pack (pack) exceeds the battery cell energy evaluation threshold, it is determined that the electrical energy of the battery cell or battery pack (pack) is high; otherwise, it is determined that the electrical energy of the battery cell or battery pack (pack) is low. It should be noted that the battery pack (pack) is a battery combination composed of multiple battery cells. When calculating the logistic regression result, calculate the logistic regression result of each battery cell in the battery pack (pack) and take the average value as the logistic regression result of the battery pack (pack).

[0060] After the equalization control module classifies the energy of the battery cells, sort the battery cells according to the electrical energy size, select k battery cells from largest to smallest and mark them as transmitting battery cells, then select the corresponding number of battery cells from smallest to largest and mark them as receiving battery cells. Randomly select one battery cell from the transmitting battery cells and the receiving battery cells respectively, and transfer the energy of the battery cell with high electrical energy to the battery cell with low electrical energy randomly. When performing energy transfer, turn on the relay corresponding to the battery cell with high electrical energy through the MCU and control the power module in the corresponding battery pack (pack) to be in the reverse mode, turn on the relay corresponding to the battery cell with low electrical energy through the MCU and control the power module in the corresponding battery pack (pack) to be in the forward mode, and transfer the electrical energy in the battery cell with high electrical energy to the battery cell with low electrical energy.

[0061] It should be noted that in this example, each master controller can be connected to multiple active equalization modules through address allocation. A battery cluster in the energy storage system contains multiple battery packs (packs), each battery pack (pack) is equipped with an active equalization module, and each time one battery cell is controlled on an equalization board. The master controller can only control one battery cell in one battery pack (pack) each time, and can control multiple battery cells in different battery packs (packs) to charge in one equalization state. Each battery pack (pack) can only work in one working mode. When performing energy transfer, the AC / DC DC power supply is used to realize the energy transfer of one battery in each of the two battery packs (packs). The quantity k selected after sorting according to the electrical energy size can be set by itself. For example, k can be set to 3, etc., which will not be elaborated here.

[0062] Since the master controller only controls one battery cell in one battery pack (pack) each time, and controls multiple battery cells in different battery packs (packs) to charge in one equalization state, and each battery pack (pack) only operates in one working mode. When the battery cells in a battery cluster perform energy transfer, the master controller in the estimation and update module automatically calculates the equalization power value according to the SOC data of the corresponding battery cell, and takes the ratio of the power value to the preset equalization current as the equalization time and marks it as t. The master controller takes the equalization time t as the time for the battery cell to perform energy transfer.

[0063] Set up a protection mechanism. When the SOC data of the current battery cluster as a whole is lower than that of other battery clusters, make a judgment. If the average voltage of the current battery cluster is lower than that of other battery clusters and lower than the preset minimum battery voltage threshold, the current battery cluster does not enter the discharge mode;

[0064] When the SOC data of the current battery cluster as a whole is higher than that of other battery clusters, make a judgment. If the average voltage of the current battery cluster is higher than that of other battery clusters and higher than the preset maximum battery voltage threshold, the current battery cluster does not enter the charging mode, and energy transfer is carried out between the current battery cluster and the battery cluster with the minimum SOC data among other battery clusters.

[0065] It should be noted that in this example, the balancing current is set to 2A for real-time monitoring. In fact, the maximum current can reach 10A. Compared with passive balancing, the working efficiency is improved. At the same time, through the protection mechanism, the potential safety hazards in each process of system operation are also reduced.

[0066] The above embodiments can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product.

[0067] Those of ordinary skill in the art can realize that the modules and algorithm steps of each example described in combination with the embodiments disclosed in this article can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software depends on the specific application of the technical solution and the invention constraints. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0068] In addition, in each embodiment of the present application, the functional modules can be integrated into one processing module, or each module can exist physically alone, or two or more modules can be integrated into one module.

[0069] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application, and all should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

[0070] Finally: The above is only the preferred embodiment of the present invention and is not used to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A bidirectional DC-DC bridge type active balancing and energy storage system, characterized in that: It includes a system self-check module, a charge and discharge control module, a balance control module and an estimation update module; The system self-check module is used to start the MCU to perform self-check, confirm the relay status, and ensure the normal operation of each module; The charge and discharge control module detects the energy of the battery cell and sends instructions to the MCU according to the energy of the battery cell. The MCU controls the relay to select different working modes. The balancing control module collects the status information of the battery cells through the MCU, classifies the battery cells into energy categories, transfers energy according to the energy categories of the battery cells, monitors the status information of each battery cell in real time, and records the SOC data before transmitting it to the estimation update module; The estimation update module calculates the balanced power according to the SOC data and obtains the energy difference between each battery cell, sets the balanced current to evaluate and calculate the balanced time, and sets the timer to control the time of the balanced process.

2. A bidirectional DC-DC bridge type active balancing and energy storage system according to claim 1, characterized in that: MCU is an integrated circuit that includes a processor core, memory and peripheral interfaces. It is used to control the relay to select the working mode and collect the status information of the battery cell. The SOC data indicates the current charge level of the battery, expressed as a percentage, which refers to the ratio of the energy currently stored in the battery to its maximum storage capacity.

3. A bidirectional DC-DC bridge type active balancing and energy storage system according to claim 1, characterized in that: The system self-test module is used to start the MCU for self-test. When starting the MCU, all circuit components in the MCU are tested, and a test current is passed to test the current passing through each circuit component in the MCU. When the current is within the preset normal current threshold, the MCU is started and the current working state of the relay is determined.

4. A bidirectional DC-DC bridge type active balancing and energy storage system according to claim 1, characterized in that: The charge and discharge control module detects the energy of the battery cell and sends instructions to the MCU according to the energy of the battery cell. The MCU controls the relay to select the charging mode or the discharging mode. The bidirectional DC-DC bridge method is used when the control relay selects the working mode. The bidirectional power supply module is powered by a DC power supply, and the relay is controlled by the MCU S32K1118 on the active balancing board. When the charging mode is selected, the MUC control relay is turned on, and the bidirectional power module works in the forward mode. The bidirectional power module transfers the power of the DC power supply to the battery cell; When the discharge mode is selected, the MCU controls the relay to open, and the bidirectional power module works in the reverse mode. The bidirectional power module transfers the electric energy on the battery cell to the DC power supply; The bidirectional power module is used to switch between charging and discharging, and the MCU S32K1118 is a microcontroller used to control the on and off of the relay.

5. A bidirectional DC-DC bridge type active balancing and energy storage system according to claim 1, characterized in that: The status information of the battery cells in the balancing control module is the electric energy of the battery cells and the charge and discharge rate of each battery cell under the working state. The charge and discharge rate is the average of the charge rate of the battery cell in the charging mode and the discharge rate in the discharge mode. The battery cell electric energy evaluation threshold is calculated by the logistic regression algorithm based on the electric energy of each battery cell and the charge and discharge rate.

6. A bidirectional DC-DC bridge type active balancing and energy storage system according to claim 5, characterized in that: The balancing control module uses a logistic regression algorithm to calculate the cell energy evaluation threshold. The specific steps are as follows: The energy and charge / discharge rate of all cells in the balancing control module are standardized using the Max-Min standardization algorithm: nore =xx min / x max -x min , where x is the energy or charge / discharge rate of each cell, x min is the minimum value of the electric energy or charge and discharge rate of all cells, x max is the maximum value of the electric energy or charge and discharge rate of all cells, x nore It is the result of normalization of the electric energy or charge and discharge rate of the corresponding battery cell; The results of the standardized electric energy and charge and discharge rate of each battery cell are calculated by the logistic regression formula: L = 1 / 1 + e -z , where L is the logistic regression result calculated for each battery cell, e is the natural base, z is the logistic regression parameter, and z is the sum of the electric energy of each battery cell and the normalized charge and discharge rate; the average value of the logistic regression results calculated for each battery cell is taken as the battery cell electric energy evaluation threshold.

7. A bidirectional DC-DC bridge type active balancing and energy storage system according to claim 6, characterized in that: For each battery cell or battery pack, the logistic regression result of the battery cell or battery pack is calculated and compared with the battery cell power evaluation threshold. When the logistic regression result of the battery cell or battery pack exceeds the battery cell power evaluation threshold, the power of the battery cell or battery pack is judged to be high; otherwise, the power of the battery cell or battery pack is judged to be low. A battery pack is a battery combination consisting of multiple battery cells. When calculating the logistic regression result, the logistic regression result of each battery cell in the battery pack is calculated and the average value is taken as the logistic regression result of the battery pack.

8. A bidirectional DC-DC bridge type active balancing and energy storage system according to claim 7, characterized in that: After the balancing control module classifies the cells by energy, it sorts the cells according to the electric energy size, selects k number of cells from large to small and marks them as transmission cells, and then selects the corresponding number of cells from small to large and marks them as receiving cells; A cell is randomly selected from the transmitting cell and the receiving cell respectively, and energy is randomly transferred from the cell with high energy to the cell with low energy; When energy transfer is performed, the relay corresponding to the battery cell with high energy is opened through the MCU and the power module in the corresponding battery pack is controlled to be in reverse mode. The relay corresponding to the battery cell with low energy is opened through the MCU and the power module in the corresponding battery pack is controlled to be in forward mode, so as to transfer the energy in the battery cell with high energy to the battery cell with low energy.

9. The bidirectional DC-DC bridge type active balancing and energy storage system according to claim 1, characterized in that: The main control in the estimation update module automatically calculates the balanced power value according to the SOC data of the corresponding battery cell, and uses the ratio of the power value to the balanced current as the balanced time and marks it as t according to the preset balanced current. The main control uses the balanced time t as the time for the battery cell to transfer energy; A protection mechanism is set. If the overall SOC data of the current battery cluster is lower than that of other battery clusters, and the average voltage of the current battery cluster is lower than that of other battery clusters and lower than the preset battery minimum voltage threshold, the current battery cluster will not enter the discharge mode. If the overall SOC data of the current battery cluster is higher than that of other battery clusters, and the average voltage of the current battery cluster is higher than that of other battery clusters and higher than the preset battery maximum voltage threshold, the current battery cluster will not be charged, and energy will be transferred from the current battery cluster to the battery cluster with the smallest SOC data among the other battery clusters.

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