Battery voltage monitoring system and method

Abstract

The invention discloses a battery voltage monitoring system and method, and particularly relates to the technical field of battery voltage measurement, and the system comprises a plurality of autonomous voltage monitoring units which are in one-to-one correspondence with each battery unit in a battery pack. Each autonomous voltage monitoring unit is integrated with an analog monitoring circuit and a temperature sensor; the temperature sensor is used for collecting the working temperature of the corresponding battery unit in real time, and the analog monitoring circuit is used for collecting the unit voltage of the corresponding battery unit in real time. Through three-layer adjustment of front-end preliminary suppression, middle-end precision guarantee and rear-end depth correction, system failure caused by a single module fault is avoided, the reliability of battery voltage monitoring is improved, through high-precision voltage balance and real-time temperature monitoring, attenuation caused by over-charge, under-charge or in-pack unbalance of the battery is reduced, and the system reliability is improved. The overall service life of the battery pack is prolonged, safety risks caused by abnormal voltage are avoided, and the battery application safety is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery voltage measurement, and more particularly to a battery voltage monitoring system and method. BACKGROUND

[0002] With the popularity of some energy storage systems and portable devices, series battery packs become the mainstream power supply scheme, such as electric vehicles requiring series batteries to be 800V+. However, the consistency difference of battery units leads to voltage imbalance of each unit in the series system, significantly increasing the risk of overcharging or undercharging, directly affecting the service life, such as PEMFC single battery voltage <0.4V will permanently damage and safety risk.

[0003] Traditional battery voltage monitoring units mostly only have a single voltage collection function, and the adjustment relies on centralized control of the back end, which has the risk of response delay and local imbalance expansion. At the same time, to ensure the measurement accuracy of the upper battery units in the series battery pack, the traditional monitoring often adopts a global boost driving mode, which leads to continuous high-load operation of the boost circuit, and the energy consumption and heat problems are prominent. If there is no boost, the upper unit is prone to measurement error due to the voltage stacking effect, and the traditional battery equalization mostly adopts a single adjustment mode, such as relying only on centralized equalization or only relying on local passive equalization, which is difficult to balance adjustment accuracy and efficiency. SUMMARY

[0004] In order to overcome the above-mentioned defects of the prior art, the present application provides a battery voltage monitoring system and method to solve the problems raised in the background art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a battery voltage monitoring system, comprising: A plurality of self-contained voltage monitoring units: the self-contained voltage monitoring units are arranged one-to-one corresponding to each battery unit in the battery pack, and each self-contained voltage monitoring unit is integrated with an analog monitoring circuit and a temperature sensor; The temperature sensor is used to collect the working temperature of the corresponding battery unit in real time, and the analog monitoring circuit is used to collect the unit voltage of the corresponding battery unit in real time and compare the difference between the unit voltage and the preset reference voltage. When the difference exceeds the first threshold value, the analog monitoring circuit realizes preliminary shunt balance of its corresponding battery unit by dynamically adjusting the duty cycle of the built-in transistor.

[0006] An intelligent drive switching module: the intelligent drive switching module is electrically connected with the plurality of self-contained voltage monitoring units, comprising a first buffer amplifier, a second buffer amplifier and a voltage switching part; The voltage switching unit is used to firstly determine whether the battery cell to be monitored is an upper battery cell. The upper battery cell is a battery cell in a high position in series connection, with a higher voltage level and being easily interfered by the stacking effect. If the battery cell is an upper battery cell, the voltage switching unit switches the driving voltage of the first buffer amplifier and the second buffer amplifier to a boosted voltage, which is higher than the system power supply voltage. If the battery cell is not an upper battery cell, the voltage switching unit configures the driving voltage of the first buffer amplifier and the second buffer amplifier as the system power supply voltage. The intelligent driving switching module is also used to receive the working temperature collected by the temperature sensor, and correct the parameters of the driving voltage according to the working temperature. When the working temperature is lower than a preset low temperature threshold, the driving voltage is increased to compensate for signal attenuation. When the working temperature is higher than a preset high temperature threshold, the driving voltage is reduced to avoid signal distortion.

[0007] The centralized diagnosis module is used to receive the cell voltage output by the autonomous voltage monitoring unit, the working temperature, and the amplified voltage signal output by the first buffer amplifier and the second buffer amplifier in real time, and determine the working state of the battery cell according to the difference between the cell voltage and the preset reference voltage, the difference between the cell voltages of the battery cells, and the working temperature. The centralized diagnosis module is electrically connected with the autonomous voltage monitoring unit and the intelligent driving switching module. When the preliminary shunt balance of the autonomous voltage monitoring unit cannot eliminate the abnormal state of the battery cell, the centralized diagnosis module triggers a deep balancing instruction to perform a deep balancing operation on the abnormal battery cell through the built-in digital regulating circuit.

[0008] Preferably, the first threshold is ±5% of the preset reference voltage. That is, when the difference between the cell voltage and the preset reference voltage exceeds ±5% of the preset reference voltage, the analog monitoring circuit (3) starts the preliminary shunt balance.

[0009] Preferably, the logic of the analog monitoring circuit (3) adjusting the transistor duty cycle is that if the cell voltage of the battery cell (2) is higher than the preset reference voltage, the transistor on-duty is increased to release excess electricity, and if the cell voltage of the battery cell (2) is lower than the preset reference voltage, the transistor on-duty is reduced to retain electricity.

[0010] Preferably, the digital regulating circuit (10) is a bidirectional balancer, and the deep balancing operation includes performing directional discharging on the overcharged battery cell (2) and performing supplemental charging on the undercharged battery cell until the cell voltages of all battery cells tend to be consistent.

[0011] Preferably, the conditions for the centralized diagnosis module to determine the abnormal state of the battery cell include: a "serious overcharge abnormality" is determined when the cell voltage of a certain battery cell continuously exceeds the preset reference voltage and is not improved after the initial shunt balance by the autonomous voltage monitoring unit; a "in-group imbalance abnormality" is determined when the cell voltage difference between any two battery cells exceeds the second threshold value.

[0012] Preferably, the second threshold value is ±% of the preset reference voltage, that is, when the cell voltage difference between any two battery cells exceeds ±% of the preset reference voltage, the "in-group imbalance abnormality" determination is triggered.

[0013] A battery voltage monitoring method is also provided, which is implemented based on the above-mentioned battery voltage monitoring system and includes the following steps: S1. Autonomous monitoring and initial balancing: Through the autonomous voltage monitoring unit corresponding to each battery cell, the cell voltage and operating temperature of the battery cell are collected in real time, the cell voltage is compared with the preset reference voltage, and if the difference exceeds the first threshold value, the transistor duty cycle is adjusted through the analog monitoring circuit to achieve initial shunt balance; S2. Intelligent driving and voltage correction: The intelligent driving switching module is used to determine whether the battery cell to be monitored is an upper battery cell, and the driving voltage of the buffer amplifier is switched as needed, with a boost voltage for the upper cell and a power supply voltage for the non-upper cell. At the same time, the driving voltage parameters are corrected according to the collected operating temperature to compensate for the influence of the environment on the signal; S3. Centralized diagnosis and deep balancing: The centralized diagnosis module is used to aggregate the collected data of the autonomous voltage monitoring unit and the amplified signals of the intelligent driving switching module, and the state of the battery cell is determined in combination with the cell voltage difference and the operating temperature. If the initial balancing cannot eliminate the abnormality, a deep balancing instruction is triggered, and the digital regulation circuit is used to perform directional discharging or supplemental charging on the abnormal cell to achieve global voltage balancing.

[0014] Preferably, in S1, the specific operation of adjusting the transistor duty cycle includes increasing the on-duty ratio when the cell voltage is too high and reducing the on-duty ratio when the cell voltage is too low.

[0015] Preferably, in S2, the specific logic for correcting the driving voltage parameters is to increase the driving voltage by 10%-15% when the operating temperature is lower than the preset low temperature threshold of -10℃, and to decrease the driving voltage by 8%-12% when the operating temperature is higher than the preset high temperature threshold of 60℃.

[0016] Preferably, in S3, the conditions for determining the abnormal state include that the cell voltage continuously exceeds the preset reference voltage and the initial balancing is ineffective, or the cell voltage difference exceeds the second threshold value (±3% of the preset reference voltage). The deep balancing operation is performed by a bidirectional balancer until the cell voltage deviation of all battery cells is less than ±1%.

[0017] Technical effects and advantages of the present application: Through the autonomous voltage monitoring unit corresponding to each battery unit, the unit voltage reflecting the power is collected in real time, and the working temperature reflecting the environmental influence is collected. When the voltage difference from the reference voltage exceeds the first threshold value, the preliminary shunt balance is immediately realized by adjusting the duty cycle of the transistor. The duty cycle is increased to release electricity when the voltage is too high, and the duty cycle is reduced to protect electricity when the voltage is too low. The problem of local imbalance expansion caused by the dependence of traditional systems on centralized control and response delay is solved. The preliminary balance at the front end can eliminate most minor voltage abnormalities, and all abnormalities do not need to be transmitted to the back end for processing, which greatly reduces the adjustment pressure of the centralized diagnosis module and improves the overall operation efficiency of the system. Through the intelligent drive switching module, only the upper battery unit susceptible to stacking effect interference uses the boost voltage, and the rest of the units use the system power voltage, replacing the traditional global boost drive mode, reducing the continuous high load running time of the boost circuit, and significantly reducing the system energy consumption and heat. Combined with the temperature sensor signal, the drive voltage is corrected, the voltage is boosted to compensate for signal attenuation at low temperature, and the voltage is reduced to avoid signal distortion at high temperature, solving the problem of large error and environmental temperature affecting accuracy of the upper unit in traditional measurement due to stacking effect, and ensuring the accuracy of voltage collection in complex environments such as high and low temperatures. Through the centralized diagnosis module, the voltage and temperature data of the autonomous unit and the high-precision amplification signal of the buffer amplifier are combined with the double judgment conditions to avoid the problem of misjudgment caused by single judgment dimension in traditional systems. When preliminary balance cannot solve the abnormality, the built-in digital regulation circuit is used to discharge the overcharged unit and supplement the power of the undercharged unit, so that the voltage deviation of all units is < ± 1%, solving the problem that traditional single regulation mode cannot balance accuracy and efficiency, and realizing global high-precision voltage balance of the battery pack.

[0018] In summary, through the mutual influence of the above multiple effects, through the three-layer regulation of preliminary suppression at the front end, accuracy guarantee at the middle end, and deep correction at the back end, each module plays its own role and cooperates, avoiding system failure caused by single module failure, significantly improving the reliability of battery voltage monitoring, reducing battery decay caused by overcharging, undercharging, or imbalance within the group through high-precision voltage balance and real-time temperature monitoring, prolonging the overall service life of the battery pack, and avoiding safety risks caused by voltage abnormalities, improving the safety of battery applications. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The figure is a schematic diagram of the system structure of the present application.

[0020] The figure is a schematic diagram of the system structure of the present application. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] As attached Figure 1 A battery voltage monitoring system is shown, comprising: Multiple autonomous voltage monitoring units 1: The autonomous voltage monitoring units 1 are arranged one-to-one correspondingly to each battery cell 2 in the battery pack, and each autonomous voltage monitoring unit 1 is integrated with an analog monitoring circuit 3 and a temperature sensor 4; The temperature sensor 4 is used to collect the operating temperature of the corresponding battery cell 2 in real time, and the analog monitoring circuit 3 is used to collect the cell voltage of the corresponding battery cell 2 in real time, and compare the difference between the cell voltage and the preset reference voltage. When the difference exceeds the first threshold, the analog monitoring circuit 3 dynamically adjusts the duty cycle of the built-in transistor to achieve preliminary shunt balance for the corresponding battery cell 2.

[0023] Intelligent drive switching module 5: The intelligent drive switching module 5 is electrically connected to the multiple autonomous voltage monitoring units 1, and includes a first buffer amplifier 6, a second buffer amplifier 7 and a voltage switching unit 8; The voltage switching unit 8 is used to first determine whether the battery cell 2 to be monitored is a superior battery cell. The superior battery cell is a battery cell that is at the highest position in series in the battery pack, has a higher voltage level, and is susceptible to interference from the stacking effect. If it is an superior battery cell, the voltage switching unit 8 switches the driving voltage of the first buffer amplifier 6 and the second buffer amplifier 7 to a boost voltage, which is higher than the system power supply voltage. If it is not an superior battery cell, the voltage switching unit 8 configures the driving voltage of the first buffer amplifier 6 and the second buffer amplifier 7 to the system power supply voltage. The intelligent drive switching module 5 is also used to receive the operating temperature collected by the temperature sensor 4 and correct the parameters of the drive voltage according to the operating temperature: when the operating temperature is lower than the preset low temperature threshold, the drive voltage is increased to compensate for signal attenuation; when the operating temperature is higher than the preset high temperature threshold, the drive voltage is reduced to avoid signal distortion.

[0024] Centralized diagnostic module 9: used to receive in real time the cell voltage and operating temperature output by the autonomous voltage monitoring unit 1, as well as the amplified voltage signals output by the first buffer amplifier 6 and the second buffer amplifier 7, and to determine the operating status of the battery cell 2 based on the difference between the cell voltage and a preset reference voltage, the cell voltage difference between each battery cell 2, and the operating temperature; The centralized diagnosis module 9 is electrically connected with the plurality of autonomous voltage monitoring units 1 and the intelligent drive switching module 5, respectively; When the preliminary shunt balance of the autonomous voltage monitoring unit 1 cannot eliminate the abnormal state of the battery cell 2, the centralized diagnosis module 9 triggers a deep balancing instruction to perform a deep balancing operation on the abnormal battery cell 2 through the built-in digital regulation circuit 10.

[0025] The first threshold is ±5% of the preset reference voltage, that is, when the difference between the cell voltage and the preset reference voltage exceeds ±5% of the preset reference voltage, the analog monitoring circuit 3 starts the preliminary shunt balance.

[0026] The logic of the analog monitoring circuit 3 adjusting the transistor duty cycle is that if the cell voltage of the battery cell 2 is higher than the preset reference voltage, the transistor on-duty ratio is increased to release excess electricity, and if the cell voltage of the battery cell 2 is lower than the preset reference voltage, the transistor on-duty ratio is reduced to retain electricity.

[0027] The digital regulation circuit 10 is a bidirectional balancer, and the deep balancing operation includes: performing directional discharge on the overcharged battery cell 2, and performing supplementary charging on the undercharged battery cell 2, until the cell voltages of all battery cells 2 tend to be consistent.

[0028] The conditions for the centralized diagnosis module 9 to judge the abnormal state of the battery cell 2 include: The cell voltage of a certain battery cell 2 is continuously higher than the preset reference voltage, and after the preliminary shunt balance of the autonomous voltage monitoring unit 1, it is still not improved, and it is determined as "serious overcharge abnormality"; The difference between the cell voltages of any two battery cells 2 exceeds the second threshold, which is determined as "in-group imbalance abnormality".

[0029] The second threshold is ±3% of the preset reference voltage, that is, when the difference between the cell voltages of any two battery cells 2 exceeds ±3% of the preset reference voltage, the "in-group imbalance abnormality" determination is triggered.

[0030] A battery voltage monitoring method is also provided, which is realized based on the above-mentioned battery voltage monitoring system and includes the following steps: S1. Autonomous monitoring and preliminary balancing: through the autonomous voltage monitoring unit 1 corresponding to each battery cell 2, the cell voltage and working temperature of the battery cell 2 are collected in real time, the cell voltage is compared with the preset reference voltage, and if the difference exceeds the first threshold, the transistor duty cycle is adjusted through the analog monitoring circuit 3 to realize preliminary shunt balance; In S1, the specific operation of adjusting the transistor duty cycle includes: increasing the on-duty ratio when the cell voltage is too high, and reducing the on-duty ratio when the cell voltage is too low; S2. Intelligent driving and voltage correction: The intelligent driving switching module 5 judges whether the battery unit 2 to be monitored is an upper battery unit, switches the driving voltage of the buffer amplifier as needed, uses a boost voltage for the upper unit, and uses a power supply voltage for the non-upper unit, and simultaneously corrects the driving voltage parameter according to the collected working temperature, compensating for the influence of the environment on the signal; In S2, the specific logic for correcting the driving voltage parameter is: when the working temperature is lower than the preset low temperature threshold -10℃, increase the driving voltage by 10%-15%, and when the working temperature is higher than the preset high temperature threshold 60℃, decrease the driving voltage by 8%-12%; S3. Centralized diagnosis and deep balancing: The centralized diagnosis module 9 collects the data collected by the autonomous voltage monitoring unit 1 and the amplified signal of the intelligent driving switching module 5, judges the state of the battery unit 2 in combination with the unit voltage difference and the working temperature, triggers the deep balancing instruction if the preliminary balancing cannot eliminate the abnormality, and executes the directed discharge or supplemental charging on the abnormal unit through the digital adjustment circuit 10 to realize the global voltage balancing. In S3, the conditions for judging abnormal states include: the unit voltage continuously exceeds the preset reference voltage and the preliminary balancing is invalid, or the voltage difference between units exceeds the second threshold of the preset reference voltage ±3%, and the deep balancing operation is executed through the bidirectional balancer until the unit voltage deviation of all battery units 2 is less than ±1%.

[0031] Finally, it should be noted that the drawings of the disclosed embodiments only involve the structures involved in the disclosed embodiments, and other structures can be referred to the usual design, and in the case of no conflict, the same embodiment and different embodiments of the present application can be combined with each other; Finally: The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A battery voltage monitoring system, characterized in that: include: Multiple autonomous voltage monitoring units (1): multiple autonomous voltage monitoring units (1) are provided in one-to-one correspondence with each battery cell (2) in the battery pack, and each autonomous voltage monitoring unit (1) is integrated with an analog monitoring circuit (3) and a temperature sensor (4); The temperature sensor (4) is used to collect the operating temperature of the corresponding battery cell (2) in real time, and the analog monitoring circuit (3) is used to collect the cell voltage of the corresponding battery cell (2) in real time, and compare the difference between the cell voltage and a preset reference voltage. When the difference exceeds a first threshold, the analog monitoring circuit (3) dynamically adjusts the duty cycle of the built-in transistor to achieve preliminary shunt balance for the corresponding battery cell (2); Intelligent drive switching module (5): the intelligent drive switching module (5) is electrically connected to the plurality of autonomous voltage monitoring units (1), and the intelligent drive switching module (5) comprises a first buffer amplifier (6), a second buffer amplifier (7) and a voltage switching unit (8); The voltage switching unit (8) is used to first determine whether the battery cell (2) to be monitored is an upper battery cell. The upper battery cell is a battery cell that is in a high position in series connection in a battery pack, has a high voltage level and is susceptible to interference from the stacking effect. If it is an upper battery cell, the voltage switching unit (8) switches the driving voltage of the first buffer amplifier (6) and the second buffer amplifier (7) to a boost voltage, and the boost voltage is higher than the system power supply voltage. If it is not an upper battery cell, the voltage switching unit (8) configures the driving voltage of the first buffer amplifier (6) and the second buffer amplifier (7) to the system power supply voltage. The intelligent drive switching module (5) is further used to receive the operating temperature collected by the temperature sensor (4), and to modify the parameters of the drive voltage according to the operating temperature: when the operating temperature is lower than a preset low temperature threshold, the drive voltage is increased to compensate for signal attenuation; when the operating temperature is higher than a preset high temperature threshold, the drive voltage is reduced to avoid signal distortion; A centralized diagnosis module (9) is configured to receive in real time the cell voltage and operating temperature output by the autonomous voltage monitoring unit (1), and the amplified voltage signals output by the first buffer amplifier (6) and the second buffer amplifier (7), and to determine the operating state of the battery cell (2) based on the difference between the cell voltage and a preset reference voltage, the cell voltage difference between each battery cell (2), and the operating temperature; The centralized diagnosis module (9) is electrically connected to the plurality of autonomous voltage monitoring units (1) and the intelligent drive switching module (5), respectively; When the preliminary shunt balancing of the autonomous voltage monitoring unit (1) cannot eliminate the abnormal state of the battery cell (2), the centralized diagnostic module (9) triggers a deep balancing instruction, and the centralized diagnostic module (9) performs a deep balancing operation on the abnormal battery cell (2) through a built-in digital adjustment circuit (10).

2. The battery voltage monitoring system according to claim 1, wherein: The first threshold is ±5% of the preset reference voltage, that is, when the difference between the cell voltage and the preset reference voltage exceeds ±5% of the preset reference voltage, the analog monitoring circuit (3) starts preliminary shunt balancing.

3. The battery voltage monitoring system according to claim 1, wherein: The logic of the analog monitoring circuit (3) adjusting the transistor duty cycle is as follows: if the cell voltage of the battery cell (2) is higher than a preset reference voltage, the transistor conduction duty cycle is increased to release excess electricity; if the cell voltage of the battery cell (2) is lower than the preset reference voltage, the transistor conduction duty cycle is reduced to retain electricity.

4. The battery voltage monitoring system according to claim 1, wherein: The digital regulation circuit (10) is a bidirectional equalizer, and the deep equalization operation includes: performing directional discharge on overcharged battery cells (2) and performing supplementary charging on undercharged battery cells (2) until the cell voltages of all battery cells (2) tend to be consistent.

5. The battery voltage monitoring system according to claim 1, wherein: The conditions for the centralized diagnostic module (9) to determine whether the battery unit (2) is in an abnormal state include: The cell voltage of a certain battery cell (2) is continuously higher than a preset reference voltage, and does not improve after preliminary shunting and balancing by the autonomous voltage monitoring unit (1), and is determined to be a "severe overcharge anomaly"; If the cell voltage difference between any two battery cells (2) exceeds the second threshold, it is determined to be "intra-group imbalance abnormality".

6. The battery voltage monitoring system according to claim 5, characterized in that: The second threshold is ±3% of the preset reference voltage, that is, when the cell voltage difference between any two battery cells (2) exceeds ±3% of the preset reference voltage, an "intra-group imbalance abnormality" determination is triggered.

7. A method for monitoring battery voltage, implemented based on the battery voltage monitoring system according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Autonomous monitoring and preliminary balancing: The autonomous voltage monitoring unit (1) corresponding to each battery cell (2) is used to collect the cell voltage and operating temperature of the battery cell (2) in real time, and compare the cell voltage with a preset reference voltage. If the difference exceeds a first threshold, the transistor duty cycle is adjusted through the analog monitoring circuit (3) to achieve preliminary shunt balance; S2. Intelligent drive and voltage correction: The intelligent drive switching module (5) determines whether the battery cell (2) to be monitored is a superior battery cell, and switches the driving voltage of the buffer amplifier as needed. The superior cell uses the boost voltage, and the non-superior cell uses the power supply voltage. At the same time, the driving voltage parameters are corrected according to the collected working temperature to compensate for the influence of the environment on the signal; S3. Centralized diagnosis and deep balancing: The centralized diagnosis module (9) aggregates the collected data of the autonomous voltage monitoring unit (1) and the amplified signal of the intelligent drive switching module (5), and judges the status of the battery cell (2) in combination with the cell voltage difference and the operating temperature. If the initial balancing cannot eliminate the abnormality, the deep balancing instruction is triggered, and the digital regulation circuit (10) performs directional discharge or supplementary charging on the abnormal cell to achieve full-domain voltage balance.

8. The method for monitoring battery voltage according to claim 7, wherein: In the step S1 , the specific operation of adjusting the transistor duty cycle includes increasing the on-duty cycle when the cell voltage is too high, and decreasing the on-duty cycle when the cell voltage is too low.

9. The method for monitoring battery voltage according to claim 7, wherein: In S2, the specific logic of correcting the driving voltage parameters is: when the operating temperature is lower than the preset low temperature threshold of -10°C, the driving voltage is increased by 10%-15%; when the operating temperature is higher than the preset high temperature threshold of 60°C, the driving voltage is reduced by 8%-12%.

10. The method for monitoring battery voltage according to claim 7, wherein: In said S3, the conditions for judging the abnormal state include: the cell voltage continuously exceeds the preset reference voltage and the preliminary balance is invalid, or the voltage difference between cells exceeds the second threshold value, and the deep balancing operation is performed by the bidirectional equalizer until the cell voltage deviation of all battery cells (2) is less than ±1%.

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