Method and system for equalizing amount of electricity of battery cell, and equalization chip

Abstract

The present application relates to the technical field of battery cell equalization control, and discloses a method and system for equalizing the amount of electricity of a battery cell, and an equalization chip. The method comprises: when a battery cell satisfies an equalization condition, if it is determined that an equalization circuit is normally connected, controlling an equalization switch to be turned on so as to execute an equalization operation on the battery cell; when executing the equalization operation on the battery cell, acquiring a first temperature difference and a second temperature difference of the equalization circuit; and when the first temperature difference and the second temperature difference satisfy a preset condition, determining an equalization state of the battery cell. In the method for equalizing the amount of electricity of the battery cell provided by the present application, by determining that the equalization circuit is in an open-circuit or short-circuit state before equalization, it is ensured that the equalization circuit satisfies the equalization condition, and after equalization is ended, by means of the temperature differences, it is determined whether the equalization is normally enabled, thereby preventing equalization failure as a result of the equalization circuit being in the open-circuit or short-circuit state, and also preventing invalid equalization of the battery cell due to other issues.

Description

Battery cell charge balancing methods, systems, and balancing chips

[0001] This application claims priority to Chinese Patent Application No. 202411731186.8, filed on November 27, 2024, entitled "Method, System and Equalization Chip for Battery Cell Power Equalization", the entire contents of which are incorporated herein by reference. Technical Field

[0002] The embodiments of this application relate to the field of battery cell equalization control technology, and in particular to a battery cell power equalization method, system and equalization chip. Background Technology

[0003] When the State of Charge (SOC) of cells in existing battery packs or battery modules is inconsistent, passive or active balancing technologies are typically used to maintain a consistent SOC. Current balancing control schemes struggle to ensure that each cell can achieve balancing control; if the SOC of cells is inconsistent, it will exacerbate the imbalance in cell charge levels. Summary of the Invention

[0004] The purpose of the embodiments of this application is to provide a cell power balancing method, system and balancing chip to solve the technical problem that the existing balancing control scheme is difficult to ensure that balancing control can be completed for each cell.

[0005] To address the aforementioned technical problems, embodiments of this application disclose the following technical solutions:

[0006] Firstly, a method for balancing battery cell charge is provided, including:

[0007] If the battery cell meets the balancing conditions, and the balancing circuit connection is confirmed to be normal, the balancing switch is controlled to be turned on to perform a balancing operation on the battery cell.

[0008] After the cell performs the balancing operation, the first temperature difference and the second temperature difference of the balancing circuit are obtained.

[0009] When the first temperature difference and the second temperature difference meet preset conditions, the equilibrium state of the battery cell is determined.

[0010] In conjunction with the first aspect, the balancing circuit includes a balancing resistor configured to consume the electrical energy of the battery cell when the balancing switch is turned on.

[0011] The method for confirming that the equalization circuit connection is normal includes:

[0012] A first current is supplied to the equalization circuit, and a first voltage is obtained across the equalization resistor;

[0013] A second current is supplied to the equalization circuit, and a second voltage is obtained across the equalization resistor;

[0014] If the difference between the first voltage and the second voltage is less than or equal to the first voltage threshold, it is determined that the equalization circuit does not have an open circuit.

[0015] Wherein, the first current is greater than the second current.

[0016] In conjunction with the first aspect, the equalization circuit includes an analog front-end chip, which has sampling pins and equalization pins. The sampling pins are connected to a sampling channel, and the equalization pins are connected to an equalization channel.

[0017] The method for confirming that the equalization circuit connection is normal includes:

[0018] Obtain the third voltage of the sampling channel and the fourth voltage of the equalization channel;

[0019] If the difference between the third voltage and the fourth voltage is greater than the second voltage threshold, it is determined that there is no short circuit in the equalization circuit.

[0020] The second voltage threshold is set to 20% to 60% of the cell's output voltage.

[0021] In conjunction with the first aspect, the balancing circuit includes a balancing resistor configured to consume the electrical energy of the battery cell when the balancing switch is turned on.

[0022] The method for obtaining the first temperature difference of the equalization loop includes:

[0023] Obtain the first temperature of the equalizing resistor before the equalizing switch is turned on;

[0024] Obtain the second temperature of the equalizing resistor after the equalizing switch is turned on;

[0025] The difference between the second temperature and the first temperature is the first temperature difference.

[0026] In conjunction with the first aspect, the equalization circuit includes an analog front-end chip configured to issue equalization control commands to control the equalization switch to be turned on;

[0027] The method for obtaining the second temperature difference of the equalization loop includes:

[0028] Obtain the third temperature of the analog front-end chip before the equalization switch is turned on;

[0029] Obtain the fourth temperature of the analog front-end chip after the equalization switch is turned on;

[0030] The difference between the fourth temperature and the third temperature is the second temperature difference.

[0031] In conjunction with the first aspect, the method for determining the equilibrium state of the battery cell when the first temperature difference and the second temperature difference satisfy preset conditions includes:

[0032] When both the first temperature difference and the second temperature difference are greater than the temperature threshold, it is determined that the battery cell is in normal balance mode.

[0033] Otherwise, it is determined that the equalization activation of the battery cell has failed;

[0034] The temperature threshold is greater than 0℃ and less than 80℃.

[0035] In conjunction with the first aspect, the equalization circuit includes an analog front-end chip and an equalization resistor, wherein the analog front-end chip is configured to issue an equalization control command to control the equalization switch to be turned on;

[0036] The equalization switch includes an equalization input terminal, an equalization output terminal, and an equalization control terminal. The equalization control terminal is connected to the analog front-end chip, and the equalization input terminal or the equalization output terminal is connected to the equalization resistor.

[0037] The method for controlling the equalization switch to be turned on includes:

[0038] The equalization control terminal receives the equalization control command;

[0039] When the equalization control command meets the conduction conditions, the equalization input terminal and the equalization output terminal are turned on, so that the equalization resistor is connected to the battery cell for equalization control.

[0040] In conjunction with the first aspect, the method for confirming that the battery cell meets the equalization conditions includes:

[0041] Obtain the SOC value and average SOC value of all battery cells;

[0042] If the difference between the SOC value of the battery cell and the average SOC value is greater than the SOC threshold, the battery cell is confirmed to meet the equalization condition.

[0043] Secondly, a cell balance state determination system is provided, the system comprising:

[0044] The control module is configured to, when the battery cell meets the balancing conditions, control the balancing switch to be turned on if it is confirmed that the balancing circuit connection is normal, so as to perform a balancing operation on the battery cell.

[0045] The acquisition module is configured to acquire a first temperature difference and a second temperature difference of the equalization circuit after the equalization operation is performed on the battery cell.

[0046] The calculation module is configured to determine the equilibrium state of the battery cell when the first temperature difference and the second temperature difference meet preset conditions.

[0047] Thirdly, an equalization chip is provided for equalization control of battery cells, including:

[0048] The first acquisition unit is configured to acquire the first voltage and the second voltage of the equalization resistor;

[0049] The first processing unit is configured to confirm that the equalization circuit connection is normal based on the first voltage and the second voltage;

[0050] The second acquisition unit is configured to acquire the first initial temperature and first temperature of the equalization resistor, and to acquire its own second initial temperature and second temperature.

[0051] The second arithmetic unit is configured to determine a first temperature difference based on the first temperature and the first initial temperature, and to determine a second temperature difference based on the second temperature and the second initial temperature;

[0052] The third processing unit is configured to determine the equilibrium state of the battery cell when the first temperature difference and the second temperature difference meet preset conditions.

[0053] The equalization chip is configured to output an equalization control command when it confirms that the battery cell meets the equalization conditions and when the equalization circuit meets the preset conditions. The equalization control command is configured to turn on the equalization switch.

[0054] One of the above technical solutions has the following advantages or beneficial effects:

[0055] This application provides a cell charge equalization method, comprising: if the cell meets the equalization conditions and the equalization circuit connection is confirmed to be normal, controlling the equalization switch to conduct to perform an equalization operation on the cell; after the cell performs the equalization operation, acquiring a first temperature difference and a second temperature difference of the equalization circuit; and determining the equalization state of the cell if the first temperature difference and the second temperature difference meet preset conditions. The cell charge equalization method provided in this application ensures that the equalization circuit meets the equalization conditions by judging the open circuit and short circuit of the equalization circuit before equalization, and judges whether the equalization is normally activated by the temperature difference after equalization, thereby avoiding equalization failure due to open circuit or short circuit in the equalization circuit, and also avoiding other problems that cause the cell to undergo invalid equalization.

[0056] This application also provides a battery cell power balancing system, comprising: a control module configured to, when the battery cell meets the balancing conditions and the balancing circuit connection is confirmed to be normal, control the balancing switch to conduct to perform a balancing operation on the battery cell; an acquisition module configured to acquire a first temperature difference and a second temperature difference of the balancing circuit after the balancing operation is performed; and a calculation module configured to determine the balancing state of the battery cell when the first temperature difference and the second temperature difference meet preset conditions. The battery cell balancing state judgment system provided in this application confirms that there are no open circuits or short circuits in the balancing circuit before balancing, and then controls the balancing switch to conduct through the control module to ensure that the balancing circuit meets the balancing conditions. After balancing is completed, the acquisition module acquires the temperature difference, and then the calculation module determines whether balancing is normally initiated. This avoids balancing failure due to open circuits or short circuits in the balancing circuit, and also avoids other problems that cause the battery cell to undergo invalid balancing. Attached Figure Description

[0057] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0058] Figure 1 is a schematic diagram of the cell power balancing method provided in an embodiment of this application;

[0059] Figure 2 is a schematic diagram of a method for confirming that there is no open circuit in the equalization loop provided in an embodiment of this application;

[0060] Figure 3 is a schematic diagram of a method for confirming that there is no short circuit in the equalization loop provided in an embodiment of this application;

[0061] Figure 4 is a flowchart illustrating the cell power balancing method provided in an embodiment of this application;

[0062] Figure 5 is a schematic diagram of the cell balancing circuit structure provided in an embodiment of this application;

[0063] Figure 6 is a schematic diagram of the cell balance state judgment system provided in an embodiment of this application;

[0064] Figure 7 is a schematic diagram of the unit connection of the equalization chip provided in the embodiment of this application. Detailed Implementation

[0065] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0066] Those skilled in the art have noted that in existing battery packs, when there are inconsistencies in the State of Charge (SOC) of battery cells, passive or active balancing techniques are typically used to control the SOC within a certain range. Due to its higher reliability, passive balancing is currently widely used. Taking passive balancing as an example, when a cell reaches the balancing condition, the cell voltage acquisition chip (AFE, Analog Front End) will activate balancing, dissipating excess power through the balancing resistor. However, currently, before balancing a cell, there is a lack of confirmation regarding the connection status of the cell's balancing circuit. Whether the connection status of the cell's balancing circuit is normal directly determines the balancing effect. Furthermore, there is a lack of confirmation regarding the cell's state after balancing is activated, resulting in an unknown balancing state and exacerbating the number of unbalanced cells.

[0067] The specific implementation methods of this application are illustrated below through examples:

[0068] As shown in Figure 1, a cell charge balancing method includes:

[0069] S1: If the battery cell meets the balancing conditions and the balancing circuit connection is confirmed to be normal, the balancing switch is turned on to perform a balancing operation on the battery cell.

[0070] Specifically, a battery pack consists of multiple cells. Within a battery pack, different cells may differ in terms of charge capacity, internal resistance, aging level, etc. These differences can lead to performance imbalances within the battery pack, thus affecting the overall performance and lifespan of the pack. Therefore, in order to maximize energy utilization, extend battery life, improve safety, and ensure the performance consistency of each cell within the battery pack, sampling equalization control technology can be used to balance the cells.

[0071] In this embodiment, the method for determining whether a battery cell requires equalization control includes: obtaining the SOC value and average SOC value of all cells; if the difference between the SOC value and the average SOC value of a cell is greater than the SOC threshold, the cell is confirmed to meet the equalization condition. Specifically, by traversing each cell in the battery pack and obtaining and recording the SOC value of each cell, the total SOC value is obtained after the traversal, and the average SOC value is obtained by combining the number of cells. Based on the output performance of the battery pack, the SOC threshold is determined, which is typically 3% to 8%. That is, when the SOC threshold is 3%, if the difference between the SOC value and the average SOC value of a cell is greater than or equal to 3%, it indicates that the cell needs equalization control; while if the difference between the SOC value and the average SOC value of a cell is less than 3%, it indicates that the cell does not need equalization control. It is worth noting that the method for confirming whether a cell needs equalization control can also be based on voltage differences, charging and discharging time differences, and temperature change differences. Among them, voltage differences are determined by observing the voltage differences between the individual cells in the battery pack. If some cells have significantly higher voltages than others, or there are large voltage differences, then equalization control may be necessary. Similarly, charge / discharge time differences are assessed by observing the differences in charge / discharge times among the individual cells in the battery pack. If some cells have significantly shorter charge or discharge times than others, or there are large time differences, then equalization control may be necessary. Temperature differences are assessed by checking the temperature differences among the individual cells in the battery pack. If some cells have significantly higher temperatures than others, or there are large temperature differences, then equalization control may be necessary.

[0072] In this application embodiment, the methods for balancing the battery cells include active balancing and passive balancing. Active balancing refers to actively adjusting the charge and discharge state of each battery in the battery pack through external circuits or systems to achieve balance between the batteries. Active balancing typically involves using a current source or current switch to transfer charge from high-charge batteries to low-charge batteries in the battery pack to ensure that the charge levels of each battery in the battery pack are relatively balanced. Passive balancing, on the other hand, refers to achieving balance between the batteries through passive components or circuits inside the battery pack. Passive balancing typically uses passive components such as resistors, diodes, or switches to balance the charge differences in the battery pack by discharging or bypassing high-charge batteries. Passive balancing does not require additional circuitry and control systems and is suitable for small-scale battery packs or applications with low balancing requirements.

[0073] As shown in Figure 5, in this embodiment of the application, the path indicated by the arrow is the equalization circuit connected to the battery Bat_n. The equalization circuit includes an equalization resistor R3 and an equalization switch Q. The equalization resistor R3 is configured to consume the battery cell's electrical energy when the equalization switch Q is turned on.

[0074] Understandably, by confirming that there are no open circuits and / or short circuits in the balancing circuit before controlling the balancing switch to conduct, energy can be saved, thereby ensuring that the cells can be effectively balanced. This ensures that the capacity of the cells in the battery pack remains consistent, thus extending the battery pack's lifespan and improving its safety.

[0075] As shown in Figure 2, in this embodiment of the application, the method for confirming that the equalization loop does not have an open circuit includes:

[0076] S101: Supply a first current to the balancing circuit and obtain a first voltage across the balancing resistor. Specifically, when the balancing switch Q is open, supply a first current to the balancing circuit so that the first current can flow through the balancing resistor R3, and obtain the first voltage across the balancing resistor R3 by a voltage sensor.

[0077] S102: Supply a second current to the balancing circuit and obtain a second voltage across the balancing resistor. Specifically, after obtaining the first voltage, reduce the first current to the second current, and measure the second voltage across the balancing resistor R3 using a voltage sensor.

[0078] S103: If the difference between the first voltage and the second voltage is less than or equal to the first voltage threshold, it is determined that the balancing circuit does not have an open circuit; wherein, the first current is greater than the second current. Specifically, after obtaining the first voltage and the second voltage, the voltage difference between the first voltage and the second voltage is calculated. Simultaneously, the first voltage threshold is obtained by multiplying the current difference between the first current and the second current by the resistance value of the balancing resistor R3. If the balancing resistor R3 is not in an open circuit, considering the presence of the second capacitor C2 in the circuit, when the first current and the second current are input, the first current and the second current will charge the second capacitor C2. Therefore, when the first current is applied, the actual current flowing through the balancing resistor R3 is less than the first current. Thus, the first voltage should be close to the product of the first current and the resistance value of the balancing resistor R3. When the second current is applied, the actual current flowing through the balancing resistor R3 is also less than the second current, and the second voltage should be close to the product of the second current and the resistance value of the balancing resistor R3. Furthermore, the difference between the first voltage and the second voltage is also smaller than the actual first voltage threshold. If all balancing resistors R3 are open circuits, when the first and second currents are applied to the balancing circuit, the voltage difference across the balancing resistors R3 will be large due to the open circuit. The resulting voltage difference between the first and second voltages will be much greater than the first voltage threshold. It is important to note that when an open circuit is detected in the balancing circuit, the marking circuit cannot be opened, and a shutdown or maintenance signal is issued.

[0079] It is understandable that by applying a first current and a second current of different magnitudes to the balancing circuit, and obtaining the voltage difference across the balancing resistor R3 based on the first current and the second current, the voltage difference is compared with the theoretically calculated first voltage threshold to determine whether there is an open circuit in the balancing resistor R3. This ensures that there is no open circuit when the cell is being balanced, allowing the cell to be effectively balanced, thereby extending the battery pack's lifespan and improving its safety.

[0080] As shown in Figure 5, in this embodiment, the balancing circuit includes an analog front-end chip. The analog front-end chip has sampling pins and balancing pins. The sampling pins are connected to a sampling channel VCn, and the balancing pins are connected to a balancing channel CBn. The sampling channel VCn is used to acquire the state information of each cell in the battery pack. Through the sampling channel VCn, the chip can sample parameters such as voltage and temperature of the cells and transmit the sampled data to the chip's internal control logic for processing and judgment. The balancing channel CBn is used to control the balancing process between the cells in the battery pack. Through the balancing channel CBn, the chip can send control signals to control the conduction or disconnection of the balancing switch Q to achieve charge balancing between the cells.

[0081] As shown in Figures 3 and 4, in this embodiment of the application, the method for confirming that the equalization loop does not have a short circuit includes:

[0082] S111: Obtain the third voltage VCn_t of the sampling channel VCn and the fourth voltage CBn_t of the equalization channel CBn. Specifically, without turning on the equalization switch Q, the analog front-end chip can obtain the first voltage on the sampling channel VCn side and the fourth voltage on the equalization channel CBn side by using the pin and the equalization pin, respectively.

[0083] S112: If the difference between the third voltage VCn_t and the fourth voltage CBn_t is greater than the second voltage threshold Vi, it is determined that there is no short circuit in the equalization circuit; where the second voltage threshold Vi is set to 20%–60% of the cell output voltage. Specifically, the voltage on the sampling channel VCn is the voltage of the nth cell Bat_n to ground, and the voltage on the equalization channel CBn is the voltage of the (n-1)th cell Bat_n-1 to ground. Therefore, if there is no short circuit between the sampling channel VCn and the equalization channel CBn, the difference between the third voltage VCn_t and the fourth voltage CBn_t should be equal to the voltage of one cell. However, if there is a short circuit between the sampling channel VCn and the equalization channel CBn, the difference between the third voltage VCn_t and the fourth voltage CBn_t will be close to 0. Therefore, selecting the range of the second voltage threshold as 20%–60% of the output voltage of a single cell is sufficient to determine whether there is a short circuit between the sampling channel VCn and the equalization channel CBn. Typically, the voltage of a single battery cell is 3.5V; therefore, the second voltage threshold ranges from 0.7V to 2.1V. It is worth noting that when a short circuit is detected in the equalization circuit, the marking circuit cannot be opened, and a shutdown or maintenance signal is issued.

[0084] It is understandable that by acquiring the voltage on the sampling channel VCn and the equalization channel CBn, and judging whether there is a short circuit between the sampling channel VCn and the equalization channel CBn based on the voltage difference between the two, it is ensured that there is no short circuit when the cell is being equalized, so that the cell can be effectively equalized, thereby extending the battery pack's lifespan and improving the battery pack's safety.

[0085] As shown in Figure 5, the analog front-end chip is configured to issue equalization control commands to control the equalization switch Q to turn on. The equalization switch Q includes an equalization input terminal, an equalization output terminal, and an equalization control terminal. The equalization control terminal is connected to the analog front-end chip, and the equalization input terminal or equalization output terminal is connected to an equalization resistor. Specifically, the equalization switch Q includes a MOSFET, where the drain of the MOSFET is the equalization input terminal of the equalization switch Q, the source of the MOSFET is the equalization output terminal of the equalization switch Q, and the gate of the MOSFET is the equalization control terminal of the equalization switch Q. When the equalization control command is high, the source and drain of the MOSFET are turned on, allowing the MOSFET, equalization resistor R3, and the battery cell to form an equalization circuit. The equalization resistor R3 dissipates the battery cell's charge through heat generation.

[0086] Understandably, MOSFETs possess fast switching characteristics and low on-resistance, enabling rapid and precise cell balancing control. By adjusting the MOSFET's on-state, charge transfer can be balanced between cells, ensuring consistent voltage and capacitance across them. Furthermore, MOSFETs exhibit high reliability and stability, operating normally over a wide current and voltage range. Through proper design and selection of high-quality MOSFETs, the reliable operation of the balancing control system can be ensured.

[0087] S2: After the cell performs the equalization operation, obtain the first temperature difference and the second temperature difference of the equalization circuit.

[0088] Specifically, the main function of the equalizing resistor R3 is to reduce the energy consumption of the battery cell by heating when the equalizing switch Q is turned on, so that the energy of the battery cell with a higher charge can be reduced, thus keeping the charge of the battery cell consistent with that of the other battery cells.

[0089] As shown in Figure 4, in this embodiment of the application, the method for obtaining the first temperature difference of the balancing circuit includes: obtaining the first temperature Ta_t of the balancing resistor before the balancing switch Q is turned on; obtaining the second temperature Tb_t of the balancing resistor R3 after the balancing switch is turned on; the difference between the second temperature Tb_t and the first temperature Ta_t is the first temperature difference. Specifically, after the balancing switch Q is turned on, the balancing resistor R3 is connected to the battery cell, and the balancing resistor R3 consumes the battery cell's electrical energy by heating. Therefore, by collecting the first temperature Ta_t on the balancing resistor R3 before the balancing switch Q is turned on, and then collecting the second temperature Tb_t on the balancing resistor R3 again after the balancing switch Q is turned on, the first temperature difference obtained by collecting the first temperature Ta_t and the second temperature Tb_t, and combining the difference between the second temperature Tb_t and the first temperature Ta_t, can further determine the actual working state of the balancing resistor R3 during the balancing process.

[0090] In this embodiment, the method for obtaining the second temperature difference of the equalization circuit includes: obtaining the third temperature Ta_(t-1) of the analog front-end chip before the equalization switch is turned on; obtaining the fourth temperature Tb_(t-1) of the analog front-end chip after the equalization switch is turned on; the difference between the fourth temperature Tb_(t-1) and the third temperature Ta_(t-1) is the second temperature difference. Specifically, during the equalization process of the battery cell, the analog front-end chip needs to collect multiple data to monitor the equalization process of the battery cell. Therefore, the temperature of the analog front-end chip before and after the equalization switch Q is turned on is different. By collecting the third and fourth temperatures of the analog front-end chip before and after the equalization switch Q is turned on, and obtaining the second temperature difference based on the difference between the fourth temperature Tb_(t-1) and the third temperature Ta_(t-1), the actual working state of the analog front-end chip during the equalization process can be further determined.

[0091] S3: Determine the equilibrium state of the battery cell when the first temperature difference and the second temperature difference meet the preset conditions.

[0092] The specific method includes: if both the first temperature difference and the second temperature difference are greater than the temperature threshold, the equalization of the battery cell is determined to be normally activated; otherwise, the equalization of the battery cell is determined to have failed. The temperature thresholds include a first temperature threshold Ti for determining whether the first temperature difference meets the condition and a second temperature threshold Tj for determining whether the second temperature difference meets the condition. Both the first temperature threshold Ti and the second temperature threshold Tj are greater than 0℃ and less than 80℃. Specifically, since the equalization resistor R3 continuously heats up during the equalization process, if the equalization resistor R3 normally controls the equalization of the battery cell, the first temperature difference must be greater than 0℃. Similarly, when controlling the equalization of the battery cell, the analog front-end chip needs to first determine whether the battery cell meets the equalization conditions, and then issue an equalization control command to turn on the equalization switch Q when the battery cell meets the equalization conditions. After the equalization switch Q is turned on, the analog front-end chip also needs to constantly monitor the changes in the battery cell's charge or SOC to ensure that the battery cell is not over-equalized. Therefore, the analog front-end chip is also constantly working, and the second temperature difference before and after the equalization switch Q is turned on can also determine whether the equalization circuit has normally equalized the battery cell. If the second temperature difference is also greater than 0℃, it can be confirmed that the analog front-end chip has performed normal equalization control. It should be noted that during normal operation, even if the analog front-end chip and equalization resistor R3 are not functioning correctly, their temperatures may still rise due to the influence of other components. Therefore, the temperature threshold can be set greater than 0℃, such as any one of the following: 5℃, 8℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, or 80℃. It is important to note that when it is determined that the cell's equalization is not activated, the cell is marked as unable to activate equalization, and a stop or maintenance signal is issued.

[0093] It is understandable that by obtaining the temperature difference between the equalization resistor R3 and the analog front-end chip before and after the equalization switch Q is turned on, and judging the temperature difference based on the temperature threshold, it is possible to confirm whether the equalization state of the battery cell is normally activated, thereby avoiding inconsistencies in the battery cells after multiple equalizations, which would affect the normal operation of the energy storage system.

[0094] In summary, the cell power equalization method provided in this application confirms the open and short circuit states of the equalization circuit before issuing the equalization control command. This ensures the equalization circuit can effectively transmit commands by ruling out faults in the equalization circuit before issuing the command. After issuing the equalization control command, the actual operating state of the equalization resistor and chip is confirmed to re-evaluate the cell's equalization status, eliminating the possibility of faults in the analog front-end chip or equalization resistor, and ultimately confirming normal equalization operation. This method does not require adding extra circuit structures to the original equalization circuit, reducing costs. Furthermore, it can identify different fault types through the original equalization circuit and confirm the equalization status, ensuring the equalization effect. It avoids problems such as abnormal conduction circuits before equalization and failure to activate the equalization command after issuance. This ensures the equalization circuit can identify faults in advance, preventing inconsistencies in the cells after multiple rounds of equalization, thus avoiding disruption to the normal operation of the energy storage system.

[0095] As shown in Figure 6, this application embodiment provides a battery cell power balancing system. The system includes: a control module configured to control the balancing switch to conduct if it is confirmed that there is no open circuit and / or short circuit in the balancing circuit when the battery cell meets the balancing conditions; an acquisition module configured to acquire a first temperature difference and a second temperature difference in the balancing circuit after the balancing switch is conducted; and a calculation module configured to determine the balancing state of the battery cell when the first temperature difference and the second temperature difference meet preset conditions.

[0096] It is understood that the cell balancing status judgment system provided in this application embodiment acquires the first, second, third, and fourth voltages before the balancing control command is issued through the acquisition module, and confirms the open and short circuit status of the balancing circuit based on the four voltages through the calculation module. After ruling out faults in the balancing circuit beforehand, the control module issues the balancing control command. Then, the acquisition module collects the first, second, third, and fourth temperatures after balancing, and the calculation module confirms the actual working status of the balancing resistor and chip based on temperature changes after the balancing control command is issued, thus judging the cell balancing status again, ruling out faults in the analog front-end chip or balancing resistor, and finally confirming that balancing is normally activated. This system does not require adding extra circuit structures to the original balancing circuit, reducing costs, and can also identify different fault types through the original balancing circuit; it can also confirm the balancing status, ensuring the balancing effect. It avoids problems such as abnormal conduction circuits before balancing and failure to activate after the balancing command is issued; thus ensuring that the balancing circuit can identify faults in advance, and even if maintenance is carried out, it avoids inconsistencies in the cells after multiple rounds of balancing, affecting the normal operation of the energy storage system.

[0097] As shown in Figure 7, this application embodiment provides an equalization chip, which includes an analog front-end chip for equalization control of the battery cell, comprising: a first acquisition unit configured to acquire a first voltage and a second voltage of the equalization resistor; a first arithmetic unit configured to confirm, based on the first voltage and the second voltage, that there is no open circuit and / or short circuit in the equalization circuit; a second acquisition unit configured to acquire a first initial temperature and a first temperature of the equalization resistor, as well as a second initial temperature and a second temperature of the equalization unit itself; a second arithmetic unit configured to determine a first temperature difference based on the first temperature and the first initial temperature, and a second temperature difference based on the second temperature and the second initial temperature; and a third arithmetic unit configured to determine the equalization state of the battery cell when the first temperature difference and the second temperature difference meet preset conditions; wherein, the equalization chip is configured to output an equalization control command when confirming that the battery cell meets the equalization conditions and that the equalization circuit meets the preset conditions, and the equalization control command is configured to turn on the equalization switch.

[0098] The above provides a detailed description of a battery cell power balancing method, system, and balancing chip provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for equalizing battery cell charge, characterized in that, include: If the battery cell meets the balancing conditions, and the balancing circuit connection is confirmed to be normal, the balancing switch is controlled to be turned on to perform a balancing operation on the battery cell. After the cell performs the balancing operation, the first temperature difference and the second temperature difference of the balancing circuit are obtained. When the first temperature difference and the second temperature difference meet preset conditions, the equilibrium state of the battery cell is determined.

2. The cell charge balancing method as described in claim 1, characterized in that, The equalization circuit includes an equalization resistor, which is configured to consume the electrical energy of the battery cell when the equalization switch is turned on. The method for confirming that the equalization circuit connection is normal includes: A first current is supplied to the equalization circuit, and a first voltage is obtained across the equalization resistor; A second current is supplied to the equalization circuit, and a second voltage is obtained across the equalization resistor; If the difference between the first voltage and the second voltage is less than or equal to the first voltage threshold, it is determined that the equalization circuit does not have an open circuit. Wherein, the first current is greater than the second current.

3. The cell charge balancing method as described in claim 1, characterized in that, The equalization circuit includes an analog front-end chip, which has sampling pins and equalization pins. The sampling pins are connected to a sampling channel, and the equalization pins are connected to an equalization channel. The method for confirming that the equalization circuit connection is normal includes: Obtain the third voltage of the sampling channel and the fourth voltage of the equalization channel; If the difference between the third voltage and the fourth voltage is greater than the second voltage threshold, it is determined that there is no short circuit in the equalization circuit. The second voltage threshold is set to 20% to 60% of the cell's output voltage.

4. The cell charge balancing method as described in claim 1, characterized in that, The equalization circuit includes an equalization resistor, which is configured to consume the electrical energy of the battery cell when the equalization switch is turned on. The method for obtaining the first temperature difference of the equalization loop includes: Obtain the first temperature of the equalizing resistor before the equalizing switch is turned on; Obtain the second temperature of the equalizing resistor after the equalizing switch is turned on; The difference between the first temperature and the second temperature is the first temperature difference.

5. The cell charge balancing method as described in claim 4, characterized in that, The equalization circuit includes an analog front-end chip, which is configured to issue equalization control commands to control the equalization switch to be turned on. The method for obtaining the second temperature difference of the equalization loop includes: Obtain the third temperature of the analog front-end chip before the equalization switch is turned on; Obtain the fourth temperature of the analog front-end chip after the equalization switch is turned on; The difference between the third temperature and the fourth temperature is the second temperature difference.

6. The cell charge balancing method as described in claim 4, characterized in that, The method for determining the equilibrium state of the battery cell when the first temperature difference and the second temperature difference meet preset conditions includes: When both the first temperature difference and the second temperature difference are greater than the temperature threshold, it is determined that the battery cell is in normal balance mode. Otherwise, it is determined that the equalization activation of the battery cell has failed; The temperature threshold is greater than 0℃ and less than 80℃.

7. The cell charge balancing method as described in claim 1, characterized in that, The equalization circuit includes an analog front-end chip and an equalization resistor. The analog front-end chip is configured to issue an equalization control command to control the equalization switch to be turned on. The equalization switch includes an equalization input terminal, an equalization output terminal, and an equalization control terminal. The equalization control terminal is connected to the analog front-end chip, and the equalization input terminal or the equalization output terminal is connected to the equalization resistor. The method for controlling the equalization switch to be turned on includes: The equalization control terminal receives the equalization control command; When the equalization control command meets the conduction conditions, the equalization input terminal and the equalization output terminal are turned on, so that the equalization resistor is connected to the battery cell for equalization control.

8. The cell charge balancing method as described in claim 1, characterized in that, The method for confirming that the battery cell meets the equalization conditions includes: Obtain the SOC value and average SOC value of all battery cells; If the difference between the SOC value of the battery cell and the average SOC value is greater than the SOC threshold, the battery cell is confirmed to meet the equalization condition.

9. A cell charge balancing system, characterized in that, The system includes: The control module is configured to, when the battery cell meets the balancing conditions, control the balancing switch to be turned on if it is confirmed that the balancing circuit connection is normal, so as to perform a balancing operation on the battery cell. The acquisition module is configured to acquire a first temperature difference and a second temperature difference of the equalization circuit after the equalization operation is performed on the battery cell. The calculation module is configured to determine the equilibrium state of the battery cell when the first temperature difference and the second temperature difference meet preset conditions.

10. An equalization chip for equalization control of battery cells, characterized in that, include: The first acquisition unit is configured to acquire the first voltage and the second voltage of the equalization resistor; The first processing unit is configured to confirm that the equalization circuit connection is normal based on the first voltage and the second voltage; The second acquisition unit is configured to acquire the first initial temperature and first temperature of the equalization resistor, and to acquire its own second initial temperature and second temperature. The second arithmetic unit is configured to determine a first temperature difference based on the first temperature and the first initial temperature, and to determine a second temperature difference based on the second temperature and the second initial temperature; The third processing unit is configured to determine the equilibrium state of the battery cell when the first temperature difference and the second temperature difference meet preset conditions. The equalization chip is configured to output an equalization control command when it confirms that the battery cell meets the equalization conditions and when the equalization circuit meets the preset conditions. The equalization control command is configured to turn on the equalization switch.

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