Battery equalization method and system and automobile

Abstract

The invention relates to the technical field of battery active equalization, and provides a battery equalization method and system and an automobile, and the method comprises the steps: when an equalization instruction is received, repeatedly executing the following steps until an equalization stopping instruction is received: controlling a gated battery to be discharged in a battery pack to charge a super capacitor through bidirectional synchronous BUCK; monitoring the state of the super capacitor in the charging process; if the super capacitor reaches the target charging state, controlling the super capacitor to charge a gated battery to be charged in the battery pack through bidirectional synchronous BUCK; monitoring the state of the super capacitor in the discharging process; and if the super capacitor reaches the target discharge state, controlling the bidirectional synchronous BUCK to stop working. According to the active equalization scheme, the system cost is reduced, and the system equalization efficiency and the overall conversion efficiency can be effectively improved due to the fact that the bidirectional synchronous BUCK circuit is used as an energy conversion circuit for battery equalization.

Description

Technical Field

[0001] The present application relates to the technical field of battery balancing, and in particular to a battery balancing method, system and automobile. Background Art

[0002] In battery pack applications, due to manufacturing differences between battery cells, different environmental stresses, and other factors, inconsistent power may occur, which will lead to reduced battery pack performance and shortened service life. Therefore, achieving power balance between battery cells is an important means to improve battery pack performance and service life.

[0003] In large energy storage systems, since the capacity of single cells is generally large, passive balancing methods with small balancing current, large energy waste and slow balancing speed are generally not adopted, and active balancing is adopted. However, due to the high cost, few manufacturers use it in actual automotive products. In addition, some discrete solutions are not widely used in practice due to their low efficiency and complex control. Summary of the invention

[0004] In view of this, the embodiments of the present disclosure provide a battery balancing method, system and vehicle to solve the technical problem of how to balance the battery cells in a large energy storage system in a low-cost and efficient active balancing manner.

[0005] According to a first aspect of an embodiment of the present disclosure, a battery balancing method is provided, which is applied to a circuit in which a battery pack and a supercapacitor are respectively connected on at least two sides of a bidirectional synchronous BUCK. The battery active balancing method comprises: upon receiving a balancing instruction, repeatedly executing the following steps until a stop balancing instruction is received: controlling a selected battery to be discharged in the battery pack to charge the supercapacitor through the bidirectional synchronous BUCK; monitoring the state of the supercapacitor during the charging process; if the supercapacitor reaches a target charging state, controlling the supercapacitor to charge the selected battery to be charged in the battery pack through the bidirectional synchronous BUCK; monitoring the state of the supercapacitor during the discharging process; and controlling the bidirectional synchronous BUCK to stop working if the supercapacitor reaches a target discharge state.

[0006] According to a second aspect of an embodiment of the present disclosure, a battery balancing system is provided, comprising: a battery gating module, a supercapacitor module, a bidirectional synchronous BUCK module and a controller, wherein the battery gating module and the supercapacitor module are respectively connected to both sides of the bidirectional synchronous BUCK module, the battery gating module is used to connect to a battery pack, the controller is connected to the battery gating module, the supercapacitor module and the bidirectional synchronous BUCK module, and the controller comprises at least a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the above method when executing the computer program.

[0007] According to a third aspect of an embodiment of the present disclosure, a car is provided, comprising a power battery, wherein the power battery comprises a plurality of battery packs, each battery pack being composed of a plurality of battery cells, and the car further comprises the above-mentioned battery balancing system, and the battery balancing system is connected to at least one battery pack of the power battery.

[0008] Compared with the prior art, the disclosed embodiment has the following beneficial effects: the battery balancing method repeatedly executes the following steps when receiving a balancing instruction until a stop balancing instruction is received: controlling the selected battery to be discharged in the battery pack to charge the supercapacitor through the bidirectional synchronous BUCK; monitoring the state of the supercapacitor during the charging process; if the supercapacitor reaches the target charging state, controlling the supercapacitor to charge the selected battery to be charged in the battery pack through the bidirectional synchronous BUCK; monitoring the state of the supercapacitor during the discharge process; if the supercapacitor reaches the target discharge state, controlling the bidirectional synchronous BUCK to stop working. Since the method is applied to a discrete balancing control circuit in which at least a battery pack and a supercapacitor are connected to both sides of the bidirectional synchronous BUCK, the system cost is reduced; and using the bidirectional synchronous BUCK circuit as the energy conversion circuit for battery balancing, compared with the ordinary BUCK circuit, it can be achieved that the control complexity is not increased much, and the system balancing efficiency and the overall conversion efficiency are effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0010] Figure 1 is a flowchart of a battery balancing method provided by an embodiment of the present disclosure;

[0011] Figure 2 is a schematic diagram of the architecture of a battery balancing system provided by an embodiment of the present disclosure;

[0012] Figure 3 1 is a schematic diagram of a circuit principle of a bidirectional synchronous BUCK module provided in an embodiment of the present disclosure;

[0013] Figure 4 It is a schematic diagram of the circuit principle of a battery gating module provided by an embodiment of the present disclosure;

[0014] Figure 5 is a schematic diagram of a circuit principle of a supercapacitor provided in an embodiment of the present disclosure;

[0015] Figure 6is a schematic diagram of the structure of a controller provided by an embodiment of the present disclosure;

[0016] Figure 7 It is a partial structural schematic diagram of a car provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0017] In the following description, specific details such as specific system structures and technologies are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present disclosure. However, it should be clear to those skilled in the art that the present disclosure may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obstructing the description of the present disclosure with unnecessary details.

[0018] See also Figure 1 In a first embodiment of the present application, a battery balancing method is provided, which is applied to a circuit in which a battery pack and a supercapacitor are respectively connected to at least two sides of a bidirectional synchronous BUCK. The battery active balancing method comprises: upon receiving a balancing instruction, repeatedly performing the following steps until a stop balancing instruction is received:

[0019] S101, controlling the selected battery to be discharged in the battery pack to charge the supercapacitor through a bidirectional synchronous BUCK;

[0020] S102, monitoring the state of the supercapacitor during the charging process;

[0021] S103, if the supercapacitor reaches the target charging state, control the supercapacitor to charge the selected battery to be charged in the battery pack through the bidirectional synchronous BUCK;

[0022] S104, monitoring the state of the supercapacitor during the discharge process;

[0023] S105, if the supercapacitor reaches the target discharge state, the bidirectional synchronous BUCK is controlled to stop working.

[0024] Among them, BUCK is used to describe a specific voltage conversion topology that can reduce a higher input voltage to a lower output voltage, so it is also called a buck converter. Specifically, it is a direct current-to-direct current (DC-DC) converter that uses components such as inductors and capacitors to achieve voltage conversion by controlling the on-off state of the switching element, and has the characteristics of high efficiency and low power consumption. In this embodiment, the bidirectional synchronous BUCK is an improved BUCK converter that can not only reduce voltage, but also work in reverse to achieve a boost function. This bidirectionality enables it to convert voltage in two directions, which is used to charge and discharge the battery pack and supercapacitor connected to both sides of the bidirectional synchronous BUCK to achieve battery balancing. Among them, "synchronous" refers to the use of synchronous rectification technology to replace traditional diode rectification to improve efficiency. Synchronous rectification is the use of low-loss switching devices such as MOSFET to replace diodes, thereby reducing losses and improving overall conversion efficiency.

[0025] For example, in a battery balancing application scenario, see Figure 2 and Figure 3 , the bidirectional synchronous BUCK includes at least: 4 MOSFETs and 1 inductor L. The 4 MOSFETs are respectively called Q1, Q2, Q3, and Q4, and are divided into two groups, each group containing two upper and lower MOSFETs. Specifically, Q1 and Q2 are located on one side of the circuit as a group, used to connect the battery pack, wherein a battery gating module is also connected between the battery pack and one side of the circuit where Q1 and Q2 are located; Q3 and Q4 are located on the other side of the circuit as another group, used to connect the supercapacitor, one end of the inductor L is connected to the common node connecting Q1 and Q2, and the other end of the inductor L is connected to the common node connecting Q3 and Q4. When the battery cells in the battery pack need to charge the supercapacitor, it is achieved by controlling switches Q1 and Q2; when the supercapacitor needs to discharge the battery cells in the battery pack, it is achieved by controlling switches Q3 and Q4.

[0026] The above-mentioned active battery balancing method uses a bidirectional synchronous BUCK circuit as an energy conversion circuit for battery balancing, and utilizes the characteristic of the bidirectional synchronous BUCK circuit that can convert voltage in two directions. For the selected discharge battery, the bidirectional synchronous BUCK circuit is used to transfer the battery power to the supercapacitor, and then for the selected rechargeable battery, the bidirectional synchronous BUCK circuit is used to transfer the power stored in the supercapacitor to the rechargeable battery, so as to achieve battery power balancing. Since a low-loss MOSFET is used in the bidirectional synchronous BUCK circuit to replace the diode in the traditional BUCK circuit, low loss is utilized, thereby effectively improving the system balancing efficiency and the overall energy conversion efficiency without increasing the control complexity.

[0027] In some optional embodiments, step S101, controlling the selected battery to be discharged in the battery pack to charge the supercapacitor through the bidirectional synchronous BUCK, includes: controlling the battery selection module to select the battery to be discharged; controlling the supercapacitor to switch to a parallel mode, and controlling the bidirectional synchronous BUCK to form a working state in which the battery to be discharged discharges to the supercapacitor.

[0028] Combination Figure 2 For example, when selecting a battery to be discharged, the battery gating module can be used to select the battery cell to transfer energy to the supercapacitor. In practical applications, the specific implementation of the battery gating module is not unique. For example, the battery gating module is composed of multiple MOSFETs or relays to form a switch matrix for selectively connecting different battery packs and individual battery cells in the battery pack. When energy needs to be transferred from a battery to a supercapacitor, the battery gating module selects a target battery cell in a battery pack and turns on the corresponding MOSFET to connect the target battery cell to the bidirectional synchronous BUCK circuit to start energy transfer. Conversely, when energy needs to be transferred from a supercapacitor to another battery, the battery gating module disconnects the current battery cell and switches to another target battery cell to complete charging or energy reflux.

[0029] Among them, the battery gating module selects which battery cell in the battery pack to be discharged, which is controlled by a controller (such as MCU) that sends a balancing instruction. The controller can select the battery to be discharged according to a predetermined battery gating strategy, and send a corresponding first gating instruction to the battery gating module. The first gating instruction can be included in the balancing instruction or sent together with the balancing instruction. The battery gating module responds to the first gating instruction to turn on the corresponding MOSFET switch to connect the corresponding target battery cell to the bidirectional synchronous BUCK circuit to start energy transmission.

[0030] The supercapacitor is composed of a plurality of capacitor units, and each capacitor unit is controlled by a control circuit to be connected in series on one side of a bidirectional synchronous BUCK capacitor, or each capacitor unit is controlled to be connected in parallel on one side of a bidirectional synchronous BUCK capacitor. In this embodiment, when a battery to be discharged is selected to transmit energy to the supercapacitor, each capacitor unit in the supercapacitor is controlled to be connected in parallel, so that the voltage on the side of the battery to be discharged is higher than the voltage on the side of the supercapacitor, thereby transmitting the power of the battery to be discharged to the supercapacitor through the bidirectional synchronous BUCK to charge the supercapacitor; when a battery to be charged is selected to receive the energy transmitted back from the supercapacitor, each capacitor unit in the supercapacitor is controlled to be connected in series, so that the voltage on the side of the supercapacitor is higher than the voltage on the side of the battery to be charged, thereby transmitting the power stored in the supercapacitor to the battery to be charged through the bidirectional synchronous BUCK to charge the battery to be charged.

[0031] After the battery to be discharged is selected and the super capacitor is controlled to be in parallel mode, the MOSFET switches Q3 and Q4 in the bidirectional synchronous BUCK circuit are controlled to be turned off, and the switches Q1 and Q2 are controlled to enable the battery to be discharged to charge the super capacitor.

[0032] In the process of charging the supercapacitor by the battery to be discharged, the voltage of the supercapacitor is monitored, and when the supercapacitor is charged to a target state, the bidirectional synchronous BUCK is controlled to stop working.

[0033] In some optional implementations, in step S102, monitoring the state of the supercapacitor during the charging process includes: monitoring whether the voltage of the supercapacitor rises to a preset first voltage threshold; if the voltage of the supercapacitor rises to the first voltage threshold, controlling the bidirectional synchronous BUCK to stop working;

[0034] If the voltage of the supercapacitor does not rise to the first voltage threshold, the bidirectional synchronous BUCK is continuously controlled to enable the battery to be discharged to charge the supercapacitor, and the voltage of the supercapacitor is continuously monitored to see whether it rises to the preset first voltage threshold.

[0035] Specifically, when the battery to be discharged charges the supercapacitor, the voltage of each capacitor unit in the supercapacitor will increase. Since the supercapacitor is in a state of multiple capacitor units in parallel, multiple capacitor units are charged in parallel. When the voltage of each capacitor unit reaches a first voltage threshold, charging the supercapacitor is stopped. At this time, the sum of the voltages of each capacitor unit in the supercapacitor should be greater than the voltage of the subsequent battery to be charged to ensure that the battery to be charged can be charged in reverse afterwards.

[0036] For example, in an application scenario, the rated voltage of the battery cell in the battery pack is 3.8V, the supercapacitor is composed of 3 capacitor units, and the first voltage threshold is preferably 2.6V. When the bidirectional synchronous BUCK is controlled to make the battery to be discharged charge the supercapacitor, the voltage of the capacitor unit starts to rise, and the voltage of the capacitor unit is monitored at the same time. If the voltage of the capacitor unit reaches 2.6V, the bidirectional synchronous BUCK continues to be controlled to charge the capacitor unit. If the voltage of the capacitor unit reaches 2.6V, the bidirectional synchronous BUCK is controlled to stop working. At this time, the sum of the voltages of the two capacitor units is 2.6*3=7.8V, which is much higher than the voltage of the battery cell in the battery pack.

[0037] After the battery to be discharged completes charging the supercapacitor, a battery to be charged will be selected, and the supercapacitor will be controlled to switch to the series mode, so that the capacitor units in the supercapacitor are connected in series, so as to control the bidirectional synchronous BUCK circuit to discharge the supercapacitor to the battery to be charged, thereby completing a battery power balancing cycle.

[0038] In some optional embodiments, when the voltage of the capacitor unit in the supercapacitor reaches a first voltage threshold, in step S103, controlling the supercapacitor to charge the selected battery to be charged in the battery pack through the bidirectional synchronous BUCK includes: controlling the battery selection module to select the battery to be charged; controlling the supercapacitor to switch to a series mode, and controlling the bidirectional synchronous BUCK to form a working state in which the supercapacitor discharges the battery to be charged.

[0039] Specifically, a battery cell is selected as the battery to be charged through the battery gating module. The voltage of the battery to be charged is generally significantly lower than the voltage of the battery to be discharged before discharge. The battery to be charged is charged by using the power transmitted from the battery to be discharged to the supercapacitor, so as to achieve the effect of battery power balance in the battery pack. The principle of gating the battery to be charged is the same as that of gating the battery to be charged. Since the specific implementation method of gating the battery to be charged has been described in detail above, it will not be repeated here.

[0040] Combination Figure 2 For example, when the supercapacitor discharges to the battery to be charged, the MOSFET switches Q1 and Q2 in the bidirectional synchronous BUCK circuit are controlled to be turned off, and the switches Q3 and Q4 are controlled to discharge the supercapacitor to the battery to be charged.

[0041] During the discharge process of the supercapacitor, it is also necessary to monitor the voltage of each capacitor unit in the supercapacitor to ensure that the voltage on the supercapacitor side is higher than the voltage of the battery to be charged.

[0042] In some optional embodiments, in step S104, monitoring the state of the supercapacitor during the discharge process includes: monitoring whether the voltage of the supercapacitor drops to a preset second voltage threshold, the second voltage threshold being less than the first voltage threshold; if the supercapacitor drops to the second voltage threshold, controlling the bidirectional synchronous BUCK to stop working; if the supercapacitor does not drop to the second voltage threshold, continuing to control the bidirectional synchronous BUCK to enable the supercapacitor to charge the battery to be charged, and continuously monitoring whether the voltage of the supercapacitor drops to the preset second voltage threshold.

[0043] The second voltage threshold is the voltage threshold of the capacitor unit in the supercapacitor. When the supercapacitor is discharged, the capacitor units are connected in series. As the discharge progresses, the voltage of the capacitor unit will gradually decrease, and the voltage of the battery to be charged will gradually increase. However, it is still necessary to ensure that the sum of the voltages of all the capacitor units in series is greater than the voltage of the battery to be charged to ensure normal discharge.

[0044] Preferably, the second voltage threshold is 1.45 V. For example, in an application scenario, it is assumed that the supercapacitor includes three capacitor units and there is a battery pack consisting of three battery cells (Cell A, Cell B and Cell C), wherein:

[0045] The voltage of Cell A is 3.8V;

[0046] The voltage of Cell B is 3.6V;

[0047] The voltage of Cell C is 3.7V.

[0048] use Figure 2 The capacitor balancing circuit shown is used to make the voltages of the battery cells in the battery pack tend to be consistent. Assuming that the balancing instruction is used to control CEL1A to discharge to CELLB. Then, firstly, the battery cell CEL1A is connected to one side of the bidirectional synchronous BUCK circuit, and the three capacitor units are connected in parallel to the other side of the bidirectional synchronous BUCK circuit. The bidirectional synchronous BUCK circuit is controlled to make the battery cell Cell A charge the capacitor unit and charge to the first voltage threshold of 2.6V. Once the capacitor unit is charged to 2.6V, it switches to battery cell CellB (3.6V) and connects to one side of the bidirectional synchronous BUCK circuit, and controls each capacitor unit to be connected in series, and then controls the bidirectional synchronous BUCK circuit to make the capacitor unit charge the battery cell CellB. At the beginning, the sum of the voltages of the three capacitor units is 2.6*3=7.8V, which is much greater than CellB (3.6V), so that the capacitor unit discharges to CellB. As the discharge progresses, the voltage of the capacitor unit will drop, while the voltage of CellB will rise. When the voltage of the capacitor unit drops to 1.45V (the voltage of the series capacitor is 1.45*3=4.35V at this time),

[0049] Connect the capacitors in series and connect them to the battery cell with lower voltage Cell B (3.6V). The capacitor will start discharging Cell B until the voltage of the single capacitor drops to 1.45V (the voltage of the series capacitor is 4.35V at this time). Repeat the rising charge and discharge steps until Cell A and Cell B are balanced to about 3.7V, and the balancing of the three batteries is completed.

[0050] In practical applications, during the process of discharging and charging the battery cells, it is also necessary to monitor the voltages of the selected battery cells, including the battery to be discharged and the battery to be charged, as well as the supercapacitor, to ensure that during the charging and discharging process, the voltages of the batteries and capacitors connected on both sides of the bidirectional synchronous BUCK circuit are within the normal range.

[0051] In some optional embodiments, after controlling the battery selection module to select the battery to be discharged, it also includes: when the voltage of the battery to be discharged is within the normal range and the polarity is normal, diagnosing whether the capacitor voltage of the supercapacitor in the parallel mode is normal, and controlling the bidirectional synchronous BUCK to form a working state in which the supercapacitor discharges to the battery to be charged; if the capacitor voltage is abnormal, reporting a fault; if the battery polarity of the battery to be discharged is abnormal, reporting a fault; if the voltage of the battery to be discharged is abnormal, reporting a fault.

[0052] This embodiment diagnoses the voltage and polarity of the discharge battery and the capacitor voltage to determine whether the requirement of the bidirectional synchronous BUCK circuit controlling the discharge of the battery to be discharged to the capacitor is met, so as to ensure that the battery discharge is in progress.

[0053] In some optional embodiments, after controlling the battery selection module to select the battery to be charged, it also includes: when the voltage of the battery to be charged is within the normal range and the polarity is normal, diagnosing whether the capacitor voltage in the series mode is normal; if the capacitor voltage is normal, controlling the bidirectional synchronous BUCK to form a working state in which the supercapacitor discharges to the battery to be charged; if the capacitor voltage is abnormal, reporting a fault; if the battery polarity of the battery to be charged is abnormal, reporting a fault; if the voltage of the battery to be charged is not within the normal range, reporting a fault.

[0054] This embodiment diagnoses the voltage and polarity of the discharging battery and the capacitor voltage to determine whether the requirement of the bidirectional synchronous BUCK circuit controlling the capacitor to discharge to the battery to be charged is met, so as to ensure that the battery charging is in progress.

[0055] In a second embodiment of the present application, a battery balancing method is provided, comprising the steps of:

[0056] S201, initialization;

[0057] S202, waiting;

[0058] S203, determining whether a balancing instruction is received;

[0059] S204, if not, return to step S202;

[0060] S205, if yes, select the battery to be discharged;

[0061] S206, diagnose whether the battery voltage is within a normal range;

[0062] S207, if not, report the fault and execute step S228;

[0063] S208, diagnose whether the battery polarity is normal;

[0064] S209, if not, report the fault and execute step S228;

[0065] S210, if yes, control the supercapacitors to be connected in parallel;

[0066] S211, diagnose whether the capacitor voltage is normal;

[0067] S212, if not, report the fault and execute step S228;

[0068] S213, if yes, control the bidirectional synchronous BUCK circuit on the battery side MOSFET to discharge the gated battery to the capacitor;

[0069] S214, diagnose whether the capacitor voltage reaches the charging threshold;

[0070] S215, if not, return to step S213;

[0071] S216, if yes, control the bidirectional synchronous BUCK circuit to stop working;

[0072] S217, controlling the battery gating module to gating the battery to be charged;

[0073] S218, diagnose whether the battery voltage is within a normal range;

[0074] S219, if not, report the fault and execute step S228;

[0075] S220, if yes, diagnose whether the battery polarity is normal;

[0076] S221, if not normal, report the fault and execute step S228;

[0077] S222, if it is normal, control the MOSFET on the capacitor side of the bidirectional synchronous BUCK circuit to discharge the capacitor to the gate battery;

[0078] S223, diagnose whether the capacitor voltage reaches the discharge threshold;

[0079] S224, if no, return to step S222;

[0080] S225, if yes, control the BUCK circuit to stop working;

[0081] S226, detecting whether a stop balancing instruction is received;

[0082] S227, if not, return to step S205;

[0083] S228, if yes, end the method.

[0084] The active battery balancing method provided in this embodiment uses a bidirectional synchronous BUCK circuit as an energy conversion circuit for battery balancing, and utilizes the characteristic of the bidirectional synchronous BUCK circuit that can convert voltage in two directions. For a selected discharge battery, the bidirectional synchronous BUCK circuit is used to transfer the battery power to a supercapacitor, and then for a selected rechargeable battery, the bidirectional synchronous BUCK circuit is used to transfer the power stored in the supercapacitor to the rechargeable battery, so as to achieve battery power balancing. Since a low-loss MOSFET is used in the bidirectional synchronous BUCK circuit to replace a diode in a traditional BUCK circuit, low loss is utilized, thereby effectively improving the system balancing efficiency and the overall energy conversion efficiency without increasing the control complexity.

[0085] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure.

[0086] In the third embodiment of the present application, see Figures 2 to 6 , provides a battery balancing system, including a battery gating module, a super capacitor module, a bidirectional synchronous BUCK module and a controller, wherein the battery gating module and the super capacitor module are respectively connected to both sides of the bidirectional synchronous BUCK module, the battery gating module is used to connect to the battery pack, and the controller is connected to the battery gating module, the super capacitor module, and the bidirectional synchronous BUCK module. Figure 6 As shown, the controller includes at least a processor 601, a memory 602, and a computer program 603 stored in the memory 602 and executable on the processor 601. When the processor 601 executes the computer program 603, the steps in the above-mentioned method embodiments are implemented. Alternatively, when the processor 601 executes the computer program 603, the functions of the modules / units in the above-mentioned device embodiments are implemented.

[0087] Specifically, combined Figure 3, the bidirectional synchronous BUCK includes at least: 4 MOSFETs and 1 inductor coil L, the 4 MOSFETs are respectively called Q1, Q2, Q3, Q4, and are divided into two groups, each group contains two upper and lower MOSFETs. Specifically, Q1 and Q2 are located on one side of the circuit, as a group, for connecting the battery pack, wherein a battery gating module is also connected between the battery pack and one side of the circuit where Q1 and Q2 are located; Q3 and Q4 are located on the other side of the circuit, as another group, for connecting the supercapacitor, one end of the inductor coil L is connected to the common node connecting Q1 and Q2, and the other end of the inductor coil L is connected to the common node connecting Q3 and Q4. When the battery cells in the battery pack need to charge the supercapacitor, it is achieved by controlling switches Q1 and Q2; when the supercapacitor needs to discharge the battery cells in the battery pack, it is achieved by controlling switches Q3 and Q4. It should be noted that the working states of Q1, Q2, Q3, and Q4 are controlled by the drive circuit, and the structure of the drive circuit is conventional technology, which is not the contribution of this application to the prior art, so it will not be repeated here.

[0088] Preferably, a current limiting circuit is also connected to the circuit of Q2 and the battery gating module. By adding a current limiting circuit to the bidirectional synchronous BUCK circuit, the battery and the circuit can be protected from overcurrent, ensuring safe and stable operation of the system. Among them, the specific implementation of the current limiting circuit is not unique, including but not limited to a resistor current limiting circuit, a diode-resistor current limiting circuit, a transistor current limiting circuit, an operational amplifier current limiting circuit, a constant current diode current limiting circuit or an integrated current limiting device.

[0089] Specifically, see Figure 4 The battery gating module includes a switch matrix composed of multiple MOSFETs, which is used to selectively connect different battery packs and individual battery cells in the battery pack, and a control circuit for controlling the operation of each MOSFET; it also includes a diagnostic circuit for performing battery voltage and / or battery polarity detection on the selected battery cells to determine whether the selected battery is normal. Among them, the control circuit and the diagnostic circuit are conventional technologies, which can be implemented as existing technologies, and the embodiments of the present application do not limit this.

[0090] In some optional embodiments, the supercapacitor module includes multiple capacitors and a control circuit, at least one switch is provided between each capacitor, and the control circuit is connected to each switch for controlling the switch to control the multiple capacitors to be connected in parallel or in series.

[0091] Specifically, see Figure 5The supercapacitor module includes three capacitor units, which are connected in parallel or in series through a control circuit. The control circuit may be composed of a plurality of switches, and at least one switch is provided between each capacitor. When charging the supercapacitor, the control circuit connects the capacitor units in parallel by controlling the corresponding switches; when discharging the supercapacitor, the control circuit connects the capacitor units in series by controlling the corresponding switches. For example, when charging the supercapacitor, the capacitor units are connected in parallel, and when the voltage of the capacitor unit rises to a first voltage threshold, the controller is notified to control the bidirectional synchronous BUCK circuit to stop working; when the supercapacitor is discharged, the capacitor units are connected in series, and when the voltage of the capacitor unit drops to a second voltage threshold, the controller is notified to control the bidirectional synchronous BUCK circuit to stop working.

[0092] Preferably, the supercapacitor module further includes a diagnostic circuit for detecting whether the voltage of the capacitor unit meets a preset voltage threshold. The diagnostic circuit can diagnose the voltage of each capacitor unit in the parallel and series models respectively to determine whether the capacitor voltage reaches a preset first voltage threshold or a second voltage threshold.

[0093] The controller may include but is not limited to a processor 601 and a memory 602. Those skilled in the art will appreciate that Figure 6 The controller is merely an example and does not constitute a limitation of the controller, and may include more or fewer components than shown in the figure, or different components.

[0094] The processor 601 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0095] The memory 602 may be an internal storage unit of the controller, for example, a hard disk or memory of the controller. The memory 602 may also be an external storage device of the controller, for example, a plug-in hard disk equipped on the controller, a smart memory card (SmartMedia Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. The memory 602 may also include both an internal storage unit of the controller and an external storage device. The memory 602 is used to store computer programs and other programs and data required by the electronic device.

[0096] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units.

[0097] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present disclosure implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. The computer program may include computer program code, and the computer program code may be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electric carrier signals and telecommunication signals.

[0098] In the fourth embodiment of the present application, see Figure 7 , provides a car, including a power battery, the power battery including a plurality of battery packs, each battery pack consisting of a plurality of battery cells, the car also includes the above-mentioned battery balancing system, and the battery active balancing system is connected to at least one battery pack of the power battery. Among them, the car in this embodiment is preferably a new energy car with a battery pack.

[0099] Specifically, combined Figures 2 to 5For example, the main control device can be the main controller in the battery management system of the car. Each battery pack can correspond to a battery balancing system. Each battery balancing system is connected to the main control device through a communication module, and the communication module is preferably a CAN communication module. In addition, the controller in the battery balancing system can be a microcomputer (MCU) such as a single-chip microcomputer. When battery power balancing is required, the main control device can send a balancing instruction to the controller in each battery balancing system, and the controller executes according to the balancing instruction. Figure 1 The steps of the method are shown.

[0100] This embodiment performs battery charge balancing by applying a battery active balancing system in a car, which can not only extend battery life and improve vehicle performance, but also enhance system safety and economy, and ultimately improve the overall user experience of the vehicle.

[0101] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present disclosure, and should all be included in the protection scope of the present disclosure.

Claims

1. A battery balancing method, characterized in that: Applied to a circuit in which a battery pack and a supercapacitor are respectively connected to at least two sides of a bidirectional synchronous BUCK, the battery balancing method includes: When receiving a balancing instruction, repeat the following steps until receiving a stop balancing instruction: Controlling the selected battery to be discharged in the battery pack to charge the supercapacitor through the bidirectional synchronous BUCK; Monitoring the state of the supercapacitor during charging; If the supercapacitor reaches the target charging state, controlling the supercapacitor to charge the selected battery to be charged in the battery pack through the bidirectional synchronous BUCK; Monitoring the state of the supercapacitor during discharge; If the supercapacitor reaches the target discharge state, the bidirectional synchronous BUCK is controlled to stop working.

2. The method according to claim 1, characterized in that The controlling the selected battery to be discharged in the battery pack to charge the supercapacitor through a bidirectional synchronous BUCK comprises: Controlling the gating module to gate the battery to be discharged; The supercapacitor is controlled to switch to a parallel mode, and the bidirectional synchronous BUCK is controlled to form a working state in which the battery to be discharged discharges to the supercapacitor.

3. The method according to claim 1 or 2, characterized in that: The monitoring of the state of the supercapacitor during the charging process includes: Monitoring whether the voltage of the supercapacitor rises to a preset first voltage threshold; If the voltage of the supercapacitor rises to a first voltage threshold, the bidirectional synchronous BUCK is controlled to stop working; If the voltage of the super capacitor does not rise to the first voltage threshold, the voltage of the super capacitor is continuously monitored to see whether it rises to the preset first voltage threshold.

4. The method according to claim 1, characterized in that: Controlling the supercapacitor to charge the selected battery to be charged in the battery pack through the bidirectional synchronous BUCK includes: Controlling the gating module to gate the battery to be charged; The supercapacitor is controlled to switch to a series mode, and the bidirectional synchronous BUCK is controlled to form a working state in which the supercapacitor discharges to the battery to be charged.

5. The method according to claim 1 or 4, characterized in that: Monitor the status of the supercapacitor during the discharge process, including: Monitoring whether the voltage of the supercapacitor drops to a preset second voltage threshold; If the supercapacitor drops to the second voltage threshold, the bidirectional synchronous BUCK is controlled to stop working; If the voltage of the supercapacitor does not drop to the second voltage threshold, the voltage of the supercapacitor is continuously monitored to determine whether it drops to a preset second voltage threshold.

6. The method according to claim 2, characterized in that After the control gating module gates the battery to be discharged, the method further includes: When the voltage of the battery to be discharged is within a normal range and the polarity is normal, diagnosing whether the capacitor voltage of the supercapacitor in parallel mode is normal; If the capacitor voltage is normal, the bidirectional synchronous BUCK is controlled to form a working state where the supercapacitor discharges to the battery to be charged; If the capacitor voltage is abnormal, a fault is reported; If the battery polarity of the battery to be discharged is abnormal, a fault is reported; If the voltage of the battery to be discharged is abnormal, a fault is reported.

7. The method according to claim 4, characterized in that After the control gating module gates the battery to be charged, the method further comprises: When the voltage of the battery to be charged is within a normal range and the polarity is normal, diagnose whether the capacitor voltage in the series mode is normal; If the capacitor voltage is normal, the bidirectional synchronous BUCK is controlled to form a working state where the supercapacitor discharges to the battery to be charged; If the capacitor voltage is abnormal, a fault is reported; If the battery polarity of the battery to be charged is abnormal, a fault is reported; If the voltage of the battery to be charged is not within a normal range, a fault is reported.

8. A battery balancing system, characterized in that: include: A battery gating module, a supercapacitor module, a bidirectional synchronous BUCK module and a controller, wherein the battery gating module and the supercapacitor module are respectively connected to both sides of the bidirectional synchronous BUCK module, the battery gating module is used to connect to a battery pack, the controller is connected to the battery gating module, the supercapacitor module and the bidirectional synchronous BUCK module, and the controller comprises at least a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the method as claimed in any one of claims 1 to 7 when executing the computer program.

9. The system according to claim 8, characterized in that The supercapacitor module includes a plurality of capacitors and a control circuit. At least one switch is provided between each capacitor. The control circuit is connected to each switch and is used to control the switch to control the plurality of capacitors to be connected in parallel or in series.

10. An automobile, comprising a power battery, wherein the power battery comprises a plurality of battery packs, each battery pack being composed of a plurality of battery cells, characterized in that: The automobile further comprises the battery balancing system according to claim 8 or 9, and the battery balancing system is connected to at least one battery pack of the power battery.

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