Passive equalization control device and control method for energy storage battery pack

Abstract

The invention provides a passive equalization control device and control method for an energy storage battery pack. The passive equalization control device comprises a plurality of battery cells connected in series and a passive equalization control system, the passive equalization control system comprises a circuit board temperature acquisition module, a plurality of voltage acquisition modules, a plurality of adaptive passive equalization modules and a control module. The self-adaptive passive equalization module comprises a plurality of equalization circuit units which are arranged in parallel; the resistance values of the equalization resistors in the plurality of equalization circuit units are different; the equalization circuit unit comprises a field effect transistor and a plurality of equalization resistors which are arranged in parallel. In the passive equalization process of the energy storage battery pack, the equalization circuit units with different current values are automatically switched according to the real-time temperature change and the voltage difference change of the circuit board, the electric energy of the single battery cells is consumed through the equalization resistors, the problem that the temperature of the acquisition circuit board is too high or the equalization time is long can be avoided, and the voltage acquisition precision and the equalization efficiency are improved.

Description

[0001] This application is the priority right of patent application No. 2024117055645 (the filing date of the prior application is November 26, 2024, and the name of the invention is A passive balancing control device and control method for an energy storage battery pack). Technical Field

[0002] The present invention belongs to the technical field of energy storage battery management systems, and relates to a passive balancing control device and a control method for an energy storage battery pack. Background Art

[0003] The existing balancing solutions for energy storage batteries are mainly passive balancing and active balancing. Active balancing is the transfer of energy, and its circuit is complex and costly, so passive balancing is widely used. Passive balancing uses resistors to consume electrical energy. Due to the limitations of the circuit structure, the balancing current is small. When the circuit design is completed, the maximum balancing current is fixed. When passive balancing is enabled, the resistor consumes electrical energy and gradually generates heat that accumulates to a certain extent, causing the circuit board temperature to be too high, which will affect the acquisition of analog front-end data. If the passive balancing current is small, there is a problem of long balancing time.

[0004] CN115436782A discloses a fault detection circuit and detection method for a passive equalization circuit of a lithium battery. The circuit includes: a signal sampling unit connected in parallel with an equalization resistor, which sends a detection signal when the equalization switch is in a closed state; a signal output unit coupled with the signal sampling unit, which responds to the detection signal in the form of a level; and a control unit connected to the signal output unit, which determines whether the equalization switch fails according to the response result of the signal output unit and a preset instruction. However, it does not reflect the voltage acquisition circuit, and the equalization resistor limits the maximum value of the equalization current.

[0005] CN105633491A discloses a passive balancing circuit of a battery management system, including a central control unit, a plurality of voltage acquisition units and a plurality of electronic switch units; the voltage acquisition unit is used to collect voltage information of a single cell and transmit it to the central control unit; the central control unit analyzes the voltage information and, when it is determined that the voltage of a single cell is higher than that of other single cells, generates a discharge instruction to control the electronic switch unit to discharge the single cell; and stops discharging when it is detected that the voltage of the single cell is consistent with the voltage of other single cells.

[0006] CN107290673A discloses a passive balancing circuit and a testing method for a battery management test system, which switches a relay to a current sampling resistor, simulates the battery voltage output by connecting a programmable power supply in series, and detects the balancing current value by a current measurement function. Although the above passive balancing circuit achieves balancing through resistor discharge, it adds current sampling, makes the circuit complex, and is costly.

[0007] In addition, the above patents all fix the maximum value of the passive balancing current, and do not consider the impact of the circuit board temperature during the balancing process. When the balancing current is set too high, it is easy to cause the circuit board to generate too much heat; when the balancing current is set too low, it will take a long time to balance, affecting the acquisition accuracy of the battery management system.

[0008] In summary, providing a passive balancing control device and control method for an energy storage battery pack, fully considering the temperature change factor of the circuit board, preventing the problem of excessively high temperature of the acquisition circuit board or long balancing time, and improving voltage acquisition accuracy and balancing efficiency are problems that need to be urgently solved by technical personnel in this field. Summary of the invention

[0009] The object of the present invention is to provide a passive balancing control device and control method for an energy storage battery pack. By adding a circuit board temperature acquisition module and combining that each battery cell is connected in parallel with two balancing circuit units, during the passive balancing process of the energy storage battery pack, balancing circuit units with different current values ​​are automatically switched according to the real-time temperature change of the circuit board and the pressure difference change. The electric energy of the single battery cell is consumed through the balancing resistor, which can avoid the problem of too high temperature of the acquisition circuit board or long balancing time, and improve the voltage acquisition accuracy and balancing efficiency.

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides a passive balancing control device for an energy storage battery pack, the passive balancing control device comprising a plurality of battery cells connected in series and a passive balancing control system;

[0012] The passive balancing control system includes a circuit board temperature acquisition module, a plurality of voltage acquisition modules, a plurality of adaptive passive balancing modules and a control module;

[0013] The circuit board temperature acquisition module includes a temperature sensor device and a voltage divider resistor; one end of the temperature sensor device is connected to the control module, and the other end is grounded; one end of the voltage divider resistor is connected to the power supply, and the other end is connected to the temperature sensor device;

[0014] The voltage acquisition module is connected to the voltage output end of each battery cell to detect its output voltage and feed it back to the control module;

[0015] The adaptive passive balancing module includes a plurality of balancing circuit units arranged in parallel; the resistance values ​​of the balancing resistors in the plurality of balancing circuit units are different; the balancing circuit unit includes a field effect tube and a plurality of balancing resistors arranged in parallel; the source of the field effect tube is independently connected to the voltage acquisition module and the positive electrode of the battery cell; the drain of the field effect tube is independently connected to one end of the plurality of balancing resistors, and the other ends of the plurality of balancing resistors are independently connected to the voltage acquisition module and the negative electrode of the battery cell; the gate of the field effect tube is connected to the control module;

[0016] The control module is used to receive data from the circuit board temperature acquisition module and the voltage acquisition module, and automatically switch the equalization circuit unit.

[0017] In the present invention, the balancing related components are integrated on the PCB (Print Circuit Board). The temperature sensing device (ninth resistor) is an NTC (Negative Temperature Coefficient) temperature sensing device, the voltage divider resistor is the eighth resistor, and the temperature signal in the circuit board temperature acquisition module is VCC×R9 / (R8+R9), where VCC represents the positive power supply voltage of the circuit, R8 represents the resistance value of the eighth resistor, and R9 represents the resistance value of the ninth resistor. The field effect tube is a MOS (Metal Oxide Semiconductor) field effect tube.

[0018] The passive balancing control device provided by the present invention, by adding a circuit board temperature acquisition module, is combined with each battery cell being connected in parallel to two balancing circuit units. During the passive balancing process of the energy storage battery pack, balancing circuit units with different current values ​​are automatically switched according to the real-time temperature change of the circuit board and the pressure difference change. The electric energy of the single battery cell is consumed through the balancing resistor, which can avoid the problem of excessively high temperature of the acquisition circuit board or long balancing time, and improve the voltage acquisition accuracy and balancing efficiency. In addition, each balancing resistor is composed of two resistors with different resistance values ​​connected in parallel, which reduces the heat generation and reduces the power requirement for the balancing resistor.

[0019] As a preferred technical solution of the present invention, a plurality of battery cells share one circuit board temperature acquisition module.

[0020] Preferably, each of the battery cells is connected to a voltage acquisition module and an adaptive passive balancing module.

[0021] As a preferred technical solution of the present invention, the circuit board temperature acquisition module further includes: a filter circuit connected between one end of the temperature sensor device and the control module.

[0022] In the present invention, the circuit board temperature change factor is taken into account during the equalization process, and the circuit board temperature acquisition module adopts an RC filter circuit to filter out high and low frequency noises and increase the anti-interference ability of the system.

[0023] Preferably, the filtering circuit includes a seventh resistor connected in series between one end of the temperature sensing device and the control module, a fourth capacitor having one end connected to one end of the seventh resistor and the other end grounded, and a fifth capacitor having one end connected to the other end of the seventh resistor and the other end grounded.

[0024] In the present invention, the filter cut-off frequency f2 of the filter circuit is 1 / 2πR7C5, wherein R7 represents the resistance value of the seventh resistor, and C5 represents the capacitance value of the fifth capacitor.

[0025] As a preferred technical solution of the present invention, the voltage acquisition module includes a fifth resistor, a tenth resistor, a first capacitor, a second capacitor and a third capacitor.

[0026] Preferably, the fifth resistor and the tenth resistor have the same resistance value.

[0027] Preferably, the fifth resistor and the tenth resistor are both filter resistors; and the first capacitor, the second capacitor and the third capacitor are all filter capacitors.

[0028] In the present invention, the circuit board temperature change factor is considered during the equalization process, and the voltage acquisition module also adopts an RC filter circuit to filter out high and low frequency noise, increase the anti-interference ability of the system, and improve the acquisition accuracy. The filter cutoff frequency f1 of the voltage acquisition module is 1 / 2πR5C2, where R5 represents the resistance value of the fifth resistor and C2 represents the capacitance value of the second capacitor.

[0029] Preferably, one end of the fifth resistor is independently connected to the positive electrode of the field effect tube and the battery cell, and the other end is connected to the control module.

[0030] Preferably, one end of the tenth resistor is independently connected to the balancing resistor and the negative electrode of the battery cell, and the other end is connected to the control module.

[0031] Preferably, one end of the first capacitor is connected to one end of the fifth resistor, and the other end is grounded; one end of the second capacitor is connected to the other end of the fifth resistor, and the other end is grounded.

[0032] Preferably, one end of the third capacitor is connected to one end of the tenth resistor, and the other end is grounded.

[0033] In the present invention, when the cells are connected in series, the voltages of the negative and positive electrodes of adjacent cells are approximately equal, so the circuit connecting the negative and positive electrodes of adjacent cells shares the fifth resistor (ie, it is also the tenth resistor).

[0034] As a preferred technical solution of the present invention, the adaptive passive balancing module includes a first balancing circuit unit and a second balancing circuit unit which are arranged in parallel.

[0035] Preferably, the first balancing circuit unit includes a first field effect transistor, a first balancing resistor, a second balancing resistor and a current limiting resistor.

[0036] Preferably, the source of the first field effect tube is independently connected to the voltage acquisition module and the positive electrode of the battery cell; the drain of the first field effect tube is independently connected to one end of the first balancing resistor and the second balancing resistor, and the other ends of the first balancing resistor and the second balancing resistor are independently connected to the voltage acquisition module and the negative electrode of the battery cell; the gate of the first field effect tube is connected to the control module through a current limiting resistor.

[0037] Preferably, the first balancing resistor and the second balancing resistor are arranged in parallel.

[0038] In the present invention, the balancing resistor of the first balancing circuit unit is R1 / / R2 (indicating that the first balancing resistor and the second balancing resistor are connected in parallel); the maximum balancing current value is U / (R1 / / R2), wherein U is the voltage of the single cell.

[0039] Preferably, the second balancing circuit unit includes a second field effect transistor, a third balancing resistor, a fourth balancing resistor and a current limiting resistor.

[0040] Preferably, the source of the second field effect tube is independently connected to the voltage acquisition module and the positive electrode of the battery cell; the drain of the second field effect tube is independently connected to one end of the third balancing resistor and the fourth balancing resistor, and the other ends of the third balancing resistor and the fourth balancing resistor are independently connected to the voltage acquisition module and the negative electrode of the battery cell; the gate of the second field effect tube is connected to the control module through a current limiting resistor.

[0041] Preferably, the third balancing resistor and the fourth balancing resistor are arranged in parallel.

[0042] In the present invention, the balancing resistor of the second balancing circuit unit is R3 / / R4 (indicating that the third balancing resistor and the fourth balancing resistor are connected in parallel); the maximum balancing current value is U / (R3 / / R4), where U is the voltage of the single cell.

[0043] It is worth noting that according to the real-time temperature changes and pressure difference changes of the circuit board, the first field effect tube or the second field effect tube is adaptively controlled to be closed, and the electric energy of the single cell is consumed through the balancing resistor, thereby reducing the impact of the heat generated by the balancing current on the circuit board, improving the voltage collection accuracy, solving the problem of long balancing time, and improving the balancing efficiency.

[0044] As a preferred technical solution of the present invention, the control module includes a microcontroller.

[0045] Preferably, the microcontroller is connected to the circuit board temperature acquisition module via an input / output interface.

[0046] Preferably, the microcontroller is connected to the voltage collection module via a voltage collection pin.

[0047] Preferably, the microcontroller is connected to the equalizing circuit unit via a control signal.

[0048] In the present invention, each equalizing circuit unit is connected to the microcontroller via a control signal.

[0049] In a second aspect, the present invention provides a passive balancing control method for an energy storage battery pack, wherein the passive balancing control method is performed using the passive balancing control device described in the first aspect, and comprises the following steps:

[0050] S110, using a voltage acquisition module to acquire the voltage of each battery cell in the battery pack, and using a circuit board temperature acquisition module to acquire the temperature of the circuit board;

[0051] S120, judging whether the battery pack meets the balancing condition according to the voltage collection result and the temperature collection result; if it is judged that the balancing condition is met, the battery cell balancing is started; if it is judged that the balancing condition is not met, the battery cell balancing is not started;

[0052] S130, when cell balancing is turned on, according to the relationship between the circuit board temperature, the pressure difference and the corresponding set thresholds, the control module automatically switches the balancing circuit units with different current values, and determines whether the battery pack has completed the balancing process;

[0053] S140: If it is determined that the balancing process is completed, then the cell balancing is terminated; if it is determined that the balancing process is not completed, then the process returns to step S130.

[0054] The passive balancing control method provided by the present invention, during the passive balancing process of the energy storage battery pack, automatically switches the balancing circuit units with different current values ​​through the control module according to the real-time temperature changes and pressure difference changes of the circuit board, thereby realizing adaptive adjustment of the maximum balancing current, avoiding the problem of excessively high temperature of the acquisition circuit board or long balancing time, and improving the voltage acquisition accuracy and balancing efficiency.

[0055] As a preferred technical solution of the present invention, in step S120, the conditions for turning on the battery cell balancing include: the voltage difference between the battery cells is greater than 35mV, for example, it can be 38mV, 40mV, 42mV, 45mV, 50mV, 55mV or 60mV, and the temperature of the circuit board is less than 87°C, for example, it can be 86°C, 85°C, 84°C, 83°C, 82°C, 81°C or 80°C, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0056] Preferably, in step S140, the condition for ending cell balancing is: the voltage difference between the cells is less than 15mV, for example, it can be 14mV, 13mV, 12mV, 11mV, 10mV, 8mV or 5mV, etc., but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0057] As a preferred technical solution of the present invention, in step S130, the automatic switching of the control module includes the following situations:

[0058] If the collected circuit board temperature is lower than the minimum threshold of the circuit board temperature and the voltage difference is greater than the set threshold, the first balancing circuit unit is closed by the microcontroller, the passive balancing is turned on, and it is determined whether the battery pack has completed the balancing process based on the voltage collection result; or

[0059] If the collected circuit board temperature is lower than the minimum threshold of the circuit board temperature and the voltage difference is less than the set threshold, the second balancing circuit unit is closed by the microcontroller, the passive balancing is turned on, and it is determined whether the battery pack has completed the balancing process based on the voltage collection result; or

[0060] If the collected circuit board temperature is higher than the minimum threshold of the circuit board temperature and lower than the maximum threshold of the circuit board temperature, the second balancing circuit unit is closed by the microcontroller, the passive balancing is turned on, and it is determined whether the battery pack has completed the balancing process based on the voltage collection result; or

[0061] If the collected circuit board temperature is higher than the maximum threshold of the circuit board temperature, the cell balancing is terminated.

[0062] As a preferred technical solution of the present invention, the minimum threshold value of the circuit board temperature is 62-67°C, for example, it can be 62.5°C, 63°C, 63.5°C, 64.5°C, 65°C, 65.5°C, 66°C or 66.5°C, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0063] Preferably, the maximum threshold of the circuit board temperature is 82-87°C, for example, it can be 82.5°C, 83°C, 83.5°C, 84.5°C, 85°C, 85.5°C, 86°C or 86.5°C, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0064] Preferably, the set threshold value of the voltage difference is 38-42mV, for example, it can be 38.5mV, 39mV, 39.5mV, 40mV, 40.5mV, 41mV or 41.5mV, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] The passive balancing control device and control method provided by the present invention, by adding a circuit board temperature acquisition module, in combination with each battery cell being connected in parallel to two balancing circuit units, automatically switches balancing circuit units with different current values ​​according to real-time temperature changes and pressure difference changes of the circuit board during the passive balancing process of the energy storage battery pack, consumes the electric energy of the single battery cell through the balancing resistor, can avoid the problem of excessively high temperature of the acquisition circuit board or long balancing time, and improves the voltage acquisition accuracy and balancing efficiency; in addition, each balancing resistor is composed of two resistors with different resistance values ​​connected in parallel, which reduces the heat generation and reduces the power requirement for the balancing resistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is a circuit diagram of the passive balancing control device in Example 1. DETAILED DESCRIPTION

[0068] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0069] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0070] In the following embodiments and comparative examples, the number of battery cells is not specifically limited, and those skilled in the art may determine it according to actual conditions.

[0071] Example 1

[0072] This embodiment provides a passive balancing control device for an energy storage battery pack (circuit diagram as shown in FIG. Figure 1 As shown), the passive balancing control device includes a plurality of battery cells (Bn) connected in series and a passive balancing control system;

[0073] The passive balancing control system comprises a circuit board temperature acquisition module, a plurality of voltage acquisition modules, a plurality of adaptive passive balancing modules and a control module; a plurality of battery cells (Bn) share one circuit board temperature acquisition module; each of the battery cells (Bn) is connected to a voltage acquisition module and an adaptive passive balancing module;

[0074] The circuit board temperature acquisition module comprises an NTC temperature sensor (R9) and a voltage divider resistor (R8); one end of the NTC temperature sensor (R9) is connected to the control module, and the other end is grounded; one end of the voltage divider resistor (R8) is connected to a power supply (VCC), and the other end is connected to the NTC temperature sensor (R9); the circuit board temperature acquisition module also comprises: a filter circuit connected between one end of the NTC temperature sensor (R9) and the control module; the filter circuit comprises a seventh resistor (R7) connected in series between one end of the NTC temperature sensor (R9) and the control module, a fourth capacitor (C4) having one end connected to one end of the seventh resistor (R7) and the other end being grounded, and a fifth capacitor (C5) having one end connected to the other end of the seventh resistor (R7) and the other end being grounded;

[0075] The voltage acquisition module comprises a fifth resistor (R5), a tenth resistor (R10), a first capacitor (C1), a second capacitor (C2) and a third capacitor (C3); the fifth resistor (R5) and the tenth resistor (R10) have the same resistance value; the circuit in which the negative electrodes and the positive electrodes of adjacent cells are connected shares the fifth resistor (that is, it is also the tenth resistor); the fifth resistor (R5) and the tenth resistor (R10) are both filter resistors; the first capacitor (C1), the second capacitor (C2) and the third capacitor (C3) are all filter capacitors; the fifth resistor One end of the first capacitor (C1) is connected to one end of the fifth resistor (R5) and the other end is grounded; one end of the second capacitor (C2) is connected to the other end of the fifth resistor (R5) and the other end is grounded; one end of the third capacitor (C3) is connected to one end of the tenth resistor (R10) and the other end is grounded;

[0076] The adaptive passive balancing module comprises a first balancing circuit unit and a second balancing circuit unit which are arranged in parallel; the first balancing circuit unit comprises a first MOS field effect tube (Q1), a first balancing resistor (R1), a second balancing resistor (R2) and a current limiting resistor (R6); the source of the first MOS field effect tube (Q1) is independently connected to a fifth resistor (a tenth resistor) and a positive electrode of a battery cell; the drain of the first MOS field effect tube (Q1) is independently connected to one end of the first balancing resistor (R1) and a second balancing resistor (R2), and the other ends of the first balancing resistor (R1) and the second balancing resistor (R2) are independently connected to the fifth resistor (a tenth resistor) and a negative electrode of the battery cell; the gate of the first MOS field effect tube (Q1) is connected to the control module via a current limiting resistor (R6); the first balancing resistor (R1) and the second balancing resistor (R2) are arranged in parallel;

[0077] The second balancing circuit unit comprises a second MOS field effect tube (Q2), a third balancing resistor (R3), a fourth balancing resistor (R4) and a current limiting resistor (R6); the source of the second MOS field effect tube (Q2) is independently connected to a fifth resistor (a tenth resistor) and a positive electrode of a battery cell; the drain of the second MOS field effect tube (Q2) is independently connected to one end of the third balancing resistor (R3) and a fourth balancing resistor (R4), and the other ends of the third balancing resistor (R3) and the fourth balancing resistor (R4) are independently connected to the fifth resistor (a tenth resistor) and a negative electrode of the battery cell; the gate of the second MOS field effect tube (Q2) is connected to a control module via a current limiting resistor (R6); the third balancing resistor (R3) and the fourth balancing resistor (R4) are arranged in parallel;

[0078] The control module includes a microcontroller (MCU); the microcontroller is connected to the circuit board temperature acquisition module via a general input and output interface (GPIO); the microcontroller is connected to the voltage acquisition module via a voltage acquisition pin (Cn); the microcontroller is connected to the equalization circuit unit via a control signal (Sn.m).

[0079] Example 2

[0080] This embodiment provides a passive balancing control method for an energy storage battery pack. The passive balancing control method is performed using the passive balancing control device provided in Embodiment 1, and includes the following steps:

[0081] S110, using a voltage acquisition module to acquire the voltage of each battery cell in the battery pack, and using a circuit board temperature acquisition module to acquire the temperature of the circuit board;

[0082] S120, judging whether the battery pack meets the balancing condition according to the voltage collection result and the temperature collection result; if it is judged that the balancing condition is met, the battery cell balancing is started; if it is judged that the balancing condition is not met, the battery cell balancing is not started;

[0083] In step S120, the conditions for starting the cell balancing include: the voltage difference between the cells is greater than 35 mV, and the temperature of the circuit board is less than 85°C;

[0084] S130, when cell balancing is turned on, according to the relationship between the circuit board temperature, the pressure difference and the corresponding set thresholds, the control module automatically switches the balancing circuit units with different current values, and determines whether the battery pack has completed the balancing process;

[0085] In step S130, the automatic switching of the control module includes the following situations:

[0086] If the collected circuit board temperature is lower than the minimum threshold of the circuit board temperature and the voltage difference is greater than the set threshold, the first balancing circuit unit is closed by the microcontroller, the passive balancing is turned on, and the balancing resistor consumes the electric energy of the battery cell. At this time, the maximum balancing current (I1) is U / (R1 / / R2). At the same time, during the balancing process, it is determined whether the battery pack has completed the balancing process based on the voltage collection result; or

[0087] If the collected circuit board temperature is lower than the minimum threshold of the circuit board temperature and the voltage difference is less than the set threshold, the second balancing circuit unit is closed by the microcontroller, the passive balancing is turned on, and it is determined whether the battery pack has completed the balancing process based on the voltage collection result; or

[0088] If the collected circuit board temperature is higher than the minimum threshold of the circuit board temperature and lower than the maximum threshold of the circuit board temperature, the second balancing circuit unit is closed by the microcontroller, the passive balancing is turned on, and the balancing resistor consumes the electric energy of the battery cell. At this time, the maximum balancing current (I2) is U / (R3 / / R4). At the same time, during the balancing process, it is determined whether the battery pack has completed the balancing process based on the voltage collection result; or

[0089] If the collected circuit board temperature is higher than the maximum threshold of the circuit board temperature, the cell balancing is terminated;

[0090] Specifically, the minimum threshold of the circuit board temperature is 65° C.; the maximum threshold of the circuit board temperature is 85° C.; the set threshold of the voltage difference is 40 mV;

[0091] S140, if it is determined that the balancing process is completed, then end the cell balancing; if it is determined that the balancing process is not completed, then return to step S130;

[0092] In step S140, the condition for ending the cell balancing is: the voltage difference between the cells is less than 15 mV.

[0093] The passive balancing control method provided by the present invention utilizes a corresponding passive balancing control device to automatically switch balancing circuit units with different current values ​​according to real-time temperature changes and pressure difference changes of a circuit board during the passive balancing process of an energy storage battery pack, and consumes the electric energy of a single cell through a balancing resistor, thereby avoiding the problem of excessively high temperature of the collection circuit board or long balancing time, and improving voltage collection accuracy and balancing efficiency.

[0094] Comparative Example 1

[0095] This comparative example provides a passive balancing control device for an energy storage battery pack. Except that the first balancing resistor and the second balancing resistor are arranged in series, and the third balancing resistor and the fourth balancing resistor are arranged in series, other conditions are the same as those of Example 1.

[0096] In this comparative example, when the balancing resistors in the balancing circuit unit are all set in series, under the condition of the same balancing current, the balancing resistors set in series cannot reduce the heat generation, and there is a hidden danger of discharge and heat generation of the balancing resistors, which also leads to frequent opening and closing of the balancing, increasing energy consumption.

[0097] Comparative Example 2

[0098] This comparative example provides a passive balancing control device for an energy storage battery pack. Except that the adaptive passive balancing module is only provided with one balancing circuit unit, other conditions are the same as those of Example 1.

[0099] In this comparative example, since only one balancing circuit unit is provided, although a circuit board temperature acquisition module is provided, only the circuit board temperature is added as a condition for starting balancing, but the maximum value of the balancing current cannot be automatically switched, and the problem of the influence of the heat generated by the balancing current on the circuit board or the long balancing time cannot be solved.

[0100] Comparative Example 3

[0101] This comparative example provides a passive balancing control device for an energy storage battery pack. Except that the passive balancing control system is not provided with a circuit board temperature acquisition module, other conditions are the same as those of Example 1.

[0102] In this comparative example, since a circuit board temperature acquisition module is not provided, the influence of the circuit board temperature is not considered during the system balancing process. Although two balancing circuit units are provided, the balancing circuit cannot be switched according to changes in the circuit board temperature, which may easily cause the circuit board to generate excessive heat and affect the acquisition accuracy of the battery management system.

[0103] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A passive balancing control device for an energy storage battery pack, characterized in that: The passive balancing control device comprises a plurality of battery cells connected in series and a passive balancing control system; The passive balancing control system includes a circuit board temperature acquisition module, a plurality of voltage acquisition modules, a plurality of adaptive passive balancing modules and a control module; The circuit board temperature acquisition module includes a temperature sensor device and a voltage divider resistor; one end of the temperature sensor device is connected to the control module, and the other end is grounded; one end of the voltage divider resistor is connected to the power supply, and the other end is connected to the temperature sensor device; The voltage acquisition module is connected to the voltage output end of each battery cell to detect its output voltage and feed it back to the control module; The adaptive passive balancing module includes a plurality of balancing circuit units arranged in parallel; the resistance values ​​of the balancing resistors in the plurality of balancing circuit units are different; the balancing circuit unit includes a field effect tube and a plurality of balancing resistors arranged in parallel; the source of the field effect tube is independently connected to the voltage acquisition module and the positive electrode of the battery cell; the drain of the field effect tube is independently connected to one end of the plurality of balancing resistors, and the other ends of the plurality of balancing resistors are independently connected to the voltage acquisition module and the negative electrode of the battery cell; the gate of the field effect tube is connected to the control module; The control module is used to receive data from the circuit board temperature acquisition module and the voltage acquisition module, and automatically switch the equalization circuit unit.

2. The passive balancing control device according to claim 1, characterized in that: Several battery cells share one circuit board temperature acquisition module; Preferably, each of the battery cells is connected to a voltage acquisition module and an adaptive passive balancing module.

3. The passive balancing control device according to claim 1 or 2, characterized in that: The circuit board temperature acquisition module further includes: a filter circuit connected between one end of the temperature sensor device and the control module; Preferably, the filtering circuit includes a seventh resistor connected in series between one end of the temperature sensing device and the control module, a fourth capacitor having one end connected to one end of the seventh resistor and the other end grounded, and a fifth capacitor having one end connected to the other end of the seventh resistor and the other end grounded.

4. The passive balancing control device according to any one of claims 1 to 3, characterized in that: The voltage acquisition module includes a fifth resistor, a tenth resistor, a first capacitor, a second capacitor and a third capacitor; Preferably, the fifth resistor and the tenth resistor have the same resistance value; Preferably, the fifth resistor and the tenth resistor are both filter resistors; the first capacitor, the second capacitor and the third capacitor are all filter capacitors; Preferably, one end of the fifth resistor is independently connected to the positive electrode of the field effect tube and the battery cell, and the other end is connected to the control module; Preferably, one end of the tenth resistor is independently connected to the balancing resistor and the negative electrode of the battery cell, and the other end is connected to the control module; Preferably, one end of the first capacitor is connected to one end of the fifth resistor, and the other end is grounded; one end of the second capacitor is connected to the other end of the fifth resistor, and the other end is grounded; Preferably, one end of the third capacitor is connected to one end of the tenth resistor, and the other end is grounded.

5. The passive balancing control device according to any one of claims 1 to 4, characterized in that: The adaptive passive equalization module includes a first equalization circuit unit and a second equalization circuit unit arranged in parallel; Preferably, the first balancing circuit unit comprises a first field effect transistor, a first balancing resistor, a second balancing resistor and a current limiting resistor; Preferably, the source of the first field effect tube is independently connected to the voltage acquisition module and the positive electrode of the battery cell; the drain of the first field effect tube is independently connected to one end of the first balancing resistor and the second balancing resistor, and the other ends of the first balancing resistor and the second balancing resistor are independently connected to the voltage acquisition module and the negative electrode of the battery cell; the gate of the first field effect tube is connected to the control module through a current limiting resistor; Preferably, the first balancing resistor and the second balancing resistor are arranged in parallel; Preferably, the second balancing circuit unit comprises a second field effect transistor, a third balancing resistor, a fourth balancing resistor and a current limiting resistor; Preferably, the source of the second field effect tube is independently connected to the voltage acquisition module and the positive electrode of the battery cell; the drain of the second field effect tube is independently connected to one end of the third balancing resistor and the fourth balancing resistor, and the other ends of the third balancing resistor and the fourth balancing resistor are independently connected to the voltage acquisition module and the negative electrode of the battery cell; the gate of the second field effect tube is connected to the control module through a current limiting resistor; Preferably, the third balancing resistor and the fourth balancing resistor are arranged in parallel.

6. The passive balancing control device according to any one of claims 1 to 5, characterized in that: The control module includes a microcontroller; Preferably, the microcontroller is connected to the circuit board temperature acquisition module via an input and output interface; Preferably, the microcontroller is connected to the voltage collection module via a voltage collection pin; Preferably, the microcontroller is connected to the equalizing circuit unit via a control signal.

7. A passive balancing control method for an energy storage battery pack, characterized in that: The passive balancing control method is performed using the passive balancing control device according to any one of claims 1 to 6, and comprises the following steps: S110, using a voltage acquisition module to acquire the voltage of each battery cell in the battery pack, and using a circuit board temperature acquisition module to acquire the temperature of the circuit board; S120, judging whether the battery pack meets the balancing condition according to the voltage collection result and the temperature collection result; if it is judged that the balancing condition is met, the battery cell balancing is started; if it is judged that the balancing condition is not met, the battery cell balancing is not started; S130, when cell balancing is turned on, according to the relationship between the circuit board temperature, the pressure difference and the corresponding set thresholds, the control module automatically switches the balancing circuit units with different current values, and determines whether the battery pack has completed the balancing process; S140: If it is determined that the balancing process is completed, then the cell balancing is terminated; if it is determined that the balancing process is not completed, then the process returns to step S130.

8. The passive balancing control method according to claim 7, characterized in that: In step S120, the conditions for starting the cell balancing include: the voltage difference between the cells is greater than 35 mV, and the temperature of the circuit board is less than 87°C; Preferably, in step S140, the condition for ending the cell balancing is: the voltage difference between the cells is less than 15 mV.

9. The passive balancing control method according to claim 7 or 8, characterized in that: In step S130, the automatic switching of the control module includes the following situations: If the collected circuit board temperature is lower than the minimum threshold of the circuit board temperature and the voltage difference is greater than the set threshold, the first balancing circuit unit is closed by the microcontroller, the passive balancing is turned on, and it is determined whether the battery pack has completed the balancing process based on the voltage collection result; or If the collected circuit board temperature is lower than the minimum threshold of the circuit board temperature and the voltage difference is less than the set threshold, the second balancing circuit unit is closed by the microcontroller, the passive balancing is turned on, and it is determined whether the battery pack has completed the balancing process based on the voltage collection result; or If the collected circuit board temperature is higher than the minimum threshold of the circuit board temperature and lower than the maximum threshold of the circuit board temperature, the second balancing circuit unit is closed by the microcontroller, the passive balancing is turned on, and it is determined whether the battery pack has completed the balancing process according to the voltage collection result; or If the collected circuit board temperature is higher than the maximum threshold of the circuit board temperature, the cell balancing is terminated.

10. The passive balancing control method according to claim 9, characterized in that: The minimum threshold of the circuit board temperature is 62-67°C; Preferably, the maximum threshold of the circuit board temperature is 82-87°C; Preferably, the set threshold of the voltage difference is 38-42 mV.

Images