Full-time-domain self-adaptive multi-step battery cell balancing system and full-time-domain self-adaptive multi-step battery cell balancing method

Abstract

The invention provides a full-time-domain adaptive multi-step battery cell equalization system and method, and the system comprises a BMS main control unit, a slave control sampling and equalization control unit, and a power battery PACK unit with a plurality of battery cells connected in series. The method comprises a full-time-domain temperature self-adaptive multi-step battery cell balancing strategy and a full-time-domain battery cell consistency deviation degree self-adaptive multi-step battery cell balancing strategy. And the priority of the full-time-domain temperature self-adaptive multi-step battery cell balancing strategy is higher than that of the full-time-domain battery cell consistency deviation degree self-adaptive multi-step battery cell balancing strategy. The problems of non-adjustable equalization current, large equalization heating amount, fast temperature rise, long equalization time and low equalization efficiency in the existing passive equalization technology are solved. According to the battery cell temperature and the control panel temperature monitored in real time or according to the grade degree of battery cell deviation consistency, the intelligent switching equalization circuit with temperature self-adaption or deviation degree self-adaption is carried out, and equalization current multi-step regulation and control are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile battery management systems, and in particular to a full-time domain adaptive multi-level battery cell balancing system and method. Background Art

[0002] The battery management system BMS mainly realizes important functions such as information collection, status diagnosis, high-voltage monitoring, relay control, and vehicle communication of lithium-ion batteries. A complete BMS system usually includes a master control unit and multiple slave sampling and balancing control units. In recent years, with the emergence of long-range vehicles and high-voltage platforms above 800V, the number of series cells has increased and the capacity has increased. Since each cell is inherently different, and as the battery is used for a longer time, the consistency of the cell capacity will only get worse, and the battery performance follows the "barrel effect", so that when charging, individual cells with high capacity reach the cut-off voltage first, causing the system to terminate charging early. When discharging, individual cells with low capacity reach the discharge cut-off voltage first and stop discharging, which seriously reduces the available energy of the system and greatly reduces the endurance of the vehicle. Therefore, it is necessary to balance the cells with deviated capacity in order to maintain the consistency of the cells as much as possible.

[0003] The current balancing methods include dissipative passive balancing and non-dissipative active balancing. Taking into account the complexity of system design and cost-effectiveness, passive balancing has become the mainstream. However, almost all current passive balancing circuit designs are implemented by connecting fixed-resistance balancing resistors in parallel at both ends of the battery cell. The balancing current is not adjustable, the heat generated is large, and the temperature rise rate is high. As a result, the battery cell temperature or the board temperature rises to the safety temperature threshold within a short period of time after the balancing is turned on, so the balancing has to be terminated, which seriously prolongs the balancing time and reduces the balancing efficiency, resulting in poor balancing effect. Summary of the invention

[0004] To solve the above problems, the present invention discloses a full-time domain adaptive multi-step battery cell balancing system and method. The problems of unadjustable balancing current, large balancing heat generation, fast temperature rise, long balancing time and low balancing efficiency in existing passive balancing technology are solved. The present invention performs temperature adaptive or deviation adaptive intelligent switching balancing circuit according to the real-time monitored battery cell temperature and control board temperature or according to the degree of deviation of the battery cell from consistency, so as to realize multi-step regulation of balancing current.

[0005] The specific plan is as follows:

[0006] A full-time domain adaptive multi-level battery cell balancing system, comprising a BMS main control unit, a slave control sampling and balancing control unit and a power battery PACK unit with a plurality of battery cells connected in series; the BMS main control unit is used for data processing, logical judgment, online balancing instruction issuance and offline balancing configuration of the acquired slave control data, and comprises an MCU controller and its peripheral circuits; the slave control sampling and balancing control unit is mainly used for battery cell voltage collection and monitoring, battery cell temperature collection and monitoring, balancing temperature collection and monitoring and balancing control, and comprises a sampling circuit, a power supply circuit, a balancing circuit and a balancing control circuit; the power battery PACK unit is used for power output, and is composed of a plurality of battery cells connected in series, and also comprises a plurality of NTCs for monitoring battery cell temperature.

[0007] Furthermore, the sampling circuit includes sampling of the voltage of each battery cell, several battery cell temperature sampling interfaces, and several equalization circuit temperature sampling NTCs;

[0008] Furthermore, the power supply circuit is normally powered by a number of battery cells, supporting the low-power operation function of the slave sampling and balancing control unit, so that when the system is in sleep mode, the slave sampling and balancing control unit can still monitor the battery cell voltage, battery cell temperature, and balancing temperature, and perform offline balancing control according to the configuration.

[0009] Furthermore, each battery cell has two parallel balancing circuits, each balancing circuit includes a number of fixed-resistance balancing resistors and a MOS for controlling the on-off of the balancing circuit. The resistance settings of the balancing resistors in the two parallel balancing circuits of each battery cell are different. The equivalent resistance of the first balancing resistor is R1, and the equivalent resistance of the second balancing resistor is R2. The resistance of R2 is greater than that of R1. Through the MOS control combination, each battery cell has the ability to balance three different levels of current.

[0010] A full-time domain adaptive multi-level battery cell balancing method includes a full-time domain temperature adaptive multi-level battery cell balancing strategy and a full-time domain battery cell consistency deviation degree adaptive multi-level battery cell balancing strategy; wherein the full-time domain temperature adaptive multi-level battery cell balancing strategy has a higher priority than the full-time domain battery cell consistency deviation degree adaptive multi-level battery cell balancing strategy.

[0011] The full-time temperature adaptive multi-level battery cell balancing strategy includes the following steps:

[0012] S101, the BMS main control unit determines whether a power-off command is received, and if so, executes S112; otherwise, executes S102;

[0013] S102, determining whether the set trigger equalization enabling condition is met, if so, executing S103; otherwise, executing S111;

[0014] S103, diagnosing the battery cell temperature and the equilibrium temperature;

[0015] S104, determine whether the cell temperature and the equilibrium temperature are within the range of T1-T2, if so, execute S107; otherwise, execute S105;

[0016] S105, determine whether the cell temperature and the equilibrium temperature are within the range of T1-T2, if so, execute S108; otherwise, execute S106;

[0017] S106, determine whether the cell temperature and the equilibrium temperature are within the range of T2-T3, if so, execute S109; otherwise, execute S103;

[0018] S107, enable MOSx_1 and MOSx_2 to perform level 1 maximum current balancing;

[0019] S108, enable MOSx_1 and turn off MOSx_2 to perform 2-level high current balancing;

[0020] S109, turn off MOSx_1 and enable MOSx_2 to perform 3-level small current balancing;

[0021] S110, determine whether the equilibrium termination condition is met, if so, execute S111; otherwise, execute S103;

[0022] S111, disable the equalization function;

[0023] S112, performing low power consumption configuration on the slave sampling and balancing control unit;

[0024] S113, configuring the offline balancing enable and balancing cutoff trigger conditions for the slave sampling and balancing control unit;

[0025] S114, configuration confirmation;

[0026] S115, system power down and hibernate;

[0027] S116, Silent cruise monitoring.

[0028] The full-time cell consistency deviation degree adaptive multi-level cell balancing strategy includes the following steps:

[0029] S201, the BMS main control unit determines whether a power-off instruction is received, and if so, executes S212; otherwise, executes S202;

[0030] S202, determine whether the set trigger equalization enabling condition is met, if so, execute S203; otherwise, execute S211;

[0031] S203, diagnosing the degree of deviation of the consistency of the battery cell;

[0032] S204, determine whether the cell consistency deviation level is Level 1, if satisfied, execute S207;

[0033] S205, determining whether the cell consistency deviation level is Level 2, if satisfied, executing S208;

[0034] S206, determine whether the cell consistency deviation level is Level 3, if satisfied, execute S209;

[0035] S207, enabling MOSx_1 and MOSx_2 to perform level 1 maximum current balancing;

[0036] S208, enable MOSx_1 and turn off MOSx_2 to perform 2-level high current balancing;

[0037] S209, turn off MOSx_1 and enable MOSx_2 to perform 3-level small current balancing;

[0038] S210, determine whether the equilibrium termination condition is met, if so, execute S211; otherwise, execute S203;

[0039] S211, disable the equalization function;

[0040] S212, performing low power consumption configuration on the slave sampling and balancing control unit;

[0041] S213, configuring the offline balancing enable and balancing cutoff trigger conditions for the slave sampling and balancing control unit;

[0042] S214, configuration confirmation;

[0043] S215, system power down and hibernate;

[0044] S216, silent cruise monitoring.

[0045] Furthermore, the equalization enabling condition and the equalization terminating condition may be calibrated and confirmed according to specific projects and application scenarios, and the present invention does not impose any specific limitation thereto.

[0046] Furthermore, the temperature thresholds of T1, T2, and T3 may be calibrated and confirmed according to specific projects and application scenarios, and the present invention does not impose any specific numerical restrictions.

[0047] Furthermore, the degree of deviation of the cell consistency can be calibrated and confirmed according to specific projects and application scenarios, and the present invention does not impose any specific limitation.

[0048] Furthermore, the maximum balancing current of level 1 is: Vcell*(R1+R2) / R1*R2; the large balancing current of level 2 is: Vcell* / R1; and the small balancing current of level 3 is: Vcell* / R2.

[0049] The beneficial effects of the present invention are:

[0050] 1. It can perform adaptive multi-level intelligent adjustment of the balancing current according to the real-time monitored battery cell temperature and the temperature range of the control board, reduce the accumulation of balancing heat, and avoid abnormal termination of balancing due to excessive temperature;

[0051] 2. It can perform adaptive multi-level intelligent adjustment of balancing current according to the level of cell deviation from consistency, shorten the balancing cycle, reduce balancing heat accumulation, and improve balancing efficiency;

[0052] 3. Configure the slave sampling and balancing control unit during the system power-off stage so that it can automatically trigger the adaptive multi-level balancing strategy during the system sleep stage, realize the adaptive multi-level cell balancing function in the offline state, and have the ability and characteristics of full time domain balancing;

[0053] 4. The balancing circuit can switch automatically and has the ability to balance multiple levels of current. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The system framework diagram of the present invention is

[0055] Figure 2 The figure is a flow chart of the full-time temperature adaptive multi-level battery cell balancing strategy in the present invention.

[0056] Figure 3 It is a flow chart of the multi-level battery cell balancing strategy for adaptively adjusting the deviation degree of battery cell consistency over the entire time domain in the present invention. DETAILED DESCRIPTION

[0057] The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0058] like Figure 1As shown, a full-time domain adaptive multi-level battery cell balancing system includes a BMS main control unit, a slave control sampling and balancing control unit, and a power battery PACK unit in which several battery cells are connected in series; the BMS main control unit is used for data processing, logical judgment, online balancing instruction issuance and offline balancing configuration of the acquired slave control data, including an MCU controller and its peripheral circuits; the slave control sampling and balancing control unit is mainly used for battery cell voltage collection and monitoring, battery cell temperature collection and monitoring, balancing temperature collection and monitoring and balancing control, including a sampling circuit, a power supply circuit, a balancing circuit and a balancing control circuit; the power battery PACK unit is used for power output, and is composed of several battery cells in series, and also includes several NTCs for monitoring battery cell temperature.

[0059] Among them, the sampling circuit includes sampling of the voltage of each battery cell, several battery cell temperature sampling interfaces, and several equalization circuit temperature sampling NTCs; the power supply circuit is normally powered by several battery cells, supporting the low-power operation function of the slave sampling and equalization control unit, so that in the system sleep state, the slave sampling and equalization control unit can still monitor the battery cell voltage, battery cell temperature, and equalization temperature, and perform offline equalization control according to the configuration. Each battery cell has two parallel equalization circuits, each of which contains several fixed-resistance equalization resistors and a MOS that controls the on-off of the equalization circuit. The equalization resistors on the two parallel equalization circuits of each battery cell have different resistance settings. The equivalent resistance of the first equalization resistor is R1, and the equivalent resistance of the second equalization resistor is R2. The resistance of R2 is greater than R1. Through the MOS control combination, each battery cell has the ability to balance three different levels of current.

[0060] Example 1

[0061] like Figure 2 As shown, the full-time temperature adaptive multi-level battery cell balancing strategy includes the following steps:

[0062] S101, the BMS main control unit determines whether a power-off command is received, and if so, executes S112; otherwise, executes S102;

[0063] S102, determining whether the set trigger equalization enabling condition is met, if so, executing S103; otherwise, executing S111;

[0064] S103, diagnosing the battery cell temperature and the equilibrium temperature;

[0065] S104, determine whether the cell temperature and the equilibrium temperature are within the range of T1-T2, if so, execute S107; otherwise, execute S105;

[0066] S105, determine whether the cell temperature and the equilibrium temperature are within the range of T1-T2, if so, execute S108; otherwise, execute S106;

[0067] S106, determine whether the cell temperature and the equilibrium temperature are within the range of T2-T3, if so, execute S109; otherwise, execute S103;

[0068] S107, enable MOSx_1 and MOSx_2 to perform level 1 maximum current balancing;

[0069] S108, enable MOSx_1 and turn off MOSx_2 to perform 2-level high current balancing;

[0070] S109, turn off MOSx_1 and enable MOSx_2 to perform 3-level small current balancing;

[0071] S110, determine whether the equilibrium termination condition is met, if so, execute S111; otherwise, execute S103;

[0072] S111, disable the equalization function;

[0073] S112, performing low power consumption configuration on the slave sampling and balancing control unit;

[0074] S113, configuring the offline balancing enable and balancing cutoff trigger conditions for the slave sampling and balancing control unit;

[0075] S114, configuration confirmation;

[0076] S115, system power down and hibernate;

[0077] S116, Silent cruise monitoring.

[0078] Example 2

[0079] like Figure 3 As shown, the full-time cell consistency deviation degree adaptive multi-level cell balancing strategy includes the following steps:

[0080] S201, the BMS main control unit determines whether a power-off instruction is received, and if so, executes S212; otherwise, executes S202;

[0081] S202, determine whether the set trigger equalization enabling condition is met, if so, execute S203; otherwise, execute S211;

[0082] S203, diagnosing the degree of deviation of the consistency of the battery cell;

[0083] S204, determine whether the cell consistency deviation level is Level 1, if satisfied, execute S207;

[0084] S205, determining whether the cell consistency deviation level is Level 2, if satisfied, executing S208;

[0085] S206, determine whether the cell consistency deviation level is Level 3, if satisfied, execute S209;

[0086] S207, enabling MOSx_1 and MOSx_2 to perform level 1 maximum current balancing;

[0087] S208, enable MOSx_1 and turn off MOSx_2 to perform 2-level high current balancing;

[0088] S209, turn off MOSx_1 and enable MOSx_2 to perform 3-level small current balancing;

[0089] S210, determine whether the equilibrium termination condition is met, if so, execute S211; otherwise, execute S203;

[0090] S211, disable the equalization function;

[0091] S212, performing low power consumption configuration on the slave sampling and balancing control unit;

[0092] S213, configuring the offline balancing enable and balancing cutoff trigger conditions for the slave sampling and balancing control unit;

[0093] S214, configuration confirmation;

[0094] S215, system power down and hibernate;

[0095] S216, silent cruise monitoring.

[0096] In the present invention, the equalization enabling conditions and equalization termination conditions can be calibrated and confirmed according to specific projects and application scenarios, and the present invention does not impose specific restrictions. The T1, T2, and T3 temperature thresholds can be calibrated and confirmed according to specific projects and application scenarios, and the present invention does not impose specific numerical restrictions. The cell consistency deviation level can be calibrated and confirmed according to specific projects and application scenarios, and the present invention does not impose specific restrictions.

[0097] In addition, the maximum balancing current of level 1 is: Vcell*(R1+R2) / R1*R2; the large balancing current of level 2 is: Vcell* / R1; and the small balancing current of level 3 is: Vcell* / R2.

[0098] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above-mentioned technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. A full-time adaptive multi-level cell balancing system, characterized in that: It includes a BMS main control unit, a slave control sampling and balancing control unit, and a power battery PACK unit with several battery cells connected in series; the BMS main control unit is used for data processing, logical judgment, online balancing instruction issuance and offline balancing configuration of the acquired slave control data, including an MCU controller and its peripheral circuits; the slave control sampling and balancing control unit is mainly used for battery cell voltage collection and monitoring, battery cell temperature collection and monitoring, balancing temperature collection and monitoring and balancing control, including a sampling circuit, a power supply circuit, a balancing circuit and a balancing control circuit; the power battery PACK unit is used for power output, and is composed of several battery cells connected in series, and it also includes several NTCs for monitoring battery cell temperature.

2. A full-time adaptive multi-level cell balancing system according to claim 1, characterized in that: The sampling circuit includes sampling of the voltage of each battery cell, a number of battery cell temperature sampling interfaces, and a number of equalization circuit temperature sampling NTCs.

3. A full-time domain adaptive multi-level cell balancing system according to claim 1, characterized in that: The power supply circuit is normally powered by a number of battery cells, supporting the low-power operation function of the slave sampling and balancing control unit, so that when the system is in sleep mode, the slave sampling and balancing control unit can still monitor the battery cell voltage, battery cell temperature, and balancing temperature, and perform offline balancing control according to the configuration.

4. A full-time adaptive multi-level cell balancing system according to claim 1, characterized in that: Each battery cell has two parallel balancing circuits. Each balancing circuit includes a number of fixed-resistance balancing resistors and a MOS that controls the on / off of the balancing circuit. The balancing resistors in the two parallel balancing circuits of each battery cell have different resistance settings. The equivalent resistance of the first balancing resistor is R1, and the equivalent resistance of the second balancing resistor is R2. The resistance of R2 is greater than that of R1. Through the MOS control combination, each battery cell has the ability to balance three different levels of current.

5. A full-time domain adaptive multi-level cell balancing method, characterized in that: A system as described in any one of claims 1 to 4 is adopted, including a full-time temperature adaptive multi-level battery cell balancing strategy and a full-time battery cell consistency deviation degree adaptive multi-level battery cell balancing strategy; wherein, the full-time temperature adaptive multi-level battery cell balancing strategy has a higher priority than the full-time battery cell consistency deviation degree adaptive multi-level battery cell balancing strategy.

6. A full-time domain adaptive multi-level cell balancing method according to claim 5, characterized in that: The full-time temperature adaptive multi-level battery cell balancing strategy includes the following steps: S101, the BMS main control unit determines whether a power-off command is received, and if so, executes S112; otherwise, executes S102; S102, determine whether the set trigger equalization enabling condition is met, if so, execute S103; otherwise, execute S111; S103, diagnose the battery cell temperature and the equalization temperature; S104, determine whether the battery cell temperature and the equalization temperature are within the range of T1-T2, if so, execute S107; otherwise, execute S105; S105, determine whether the cell temperature and the equilibrium temperature are within the range of T1-T2, if so, execute S108; otherwise, execute S106; S106, determine whether the cell temperature and the equilibrium temperature are within the range of T2-T3, if so, execute S109; otherwise, execute S103; S107, enable MOSx_1 and MOSx_2 to perform level 1 maximum current balancing; S108, enable MOSx_1 and turn off MOSx_2 to perform 2-level high current balancing; S109, turn off MOSx_1 and enable MOSx_2 to perform 3-level small current balancing; S110, determine whether the equilibrium termination condition is met, if so, execute S111; otherwise, execute S103; S111, disable the equalization function; S112, performing low power consumption configuration on the slave sampling and balancing control unit; S113, configuring the offline balancing enable and balancing cutoff trigger conditions for the slave sampling and balancing control unit; S114, configuration confirmation; S115, system power down and hibernate; S116, Silent cruise monitoring.

7. A full-time domain adaptive multi-level cell balancing system according to claim 5, characterized in that: The full-time cell consistency deviation degree adaptive multi-level cell balancing strategy includes the following steps: S201, the BMS main control unit determines whether a power-off instruction is received, and if so, executes S212; otherwise, executes S202; S202, determine whether the set trigger equalization enabling condition is met, if so, execute S203; otherwise, execute S211; S203, diagnosing the degree of deviation of the consistency of the battery cell; S204, determine whether the cell consistency deviation level is Level 1, if satisfied, execute S207; S205, determining whether the cell consistency deviation level is Level 2, if satisfied, executing S208; S206, determine whether the cell consistency deviation level is Level 3, if satisfied, execute S209; S207, enabling MOSx_1 and MOSx_2 to perform level 1 maximum current balancing; S208, enable MOSx_1 and turn off MOSx_2 to perform 2-level high current balancing; S209, turn off MOSx_1 and enable MOSx_2 to perform 3-level small current balancing; S210, determine whether the equilibrium termination condition is met, if so, execute S211; otherwise, execute S203; S211, disable the equalization function; S212, performing low power consumption configuration on the slave sampling and balancing control unit; S213, configuring the offline balancing enable and balancing cutoff trigger conditions for the slave sampling and balancing control unit; S214, configuration confirmation; S215, system power down and hibernate; S216, silent cruise monitoring.

8. A full-time domain adaptive multi-level cell balancing system according to claim 6 or 7, characterized in that: The maximum balancing current of level 1 is: Vcell*(R1+R2) / R1*R2; the large balancing current of level 2 is: Vcell* / R1; the small balancing current of level 3 is: Vcell* / R2.

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