Active balancing method and active balancing device with adaptive number of battery cell strings

Abstract

The invention discloses an active balancing method and device with adaptive number of battery cell strings, which is used for balancing by an active balancing circuit. The active balancing circuit comprises a first gating unit, a second gating unit and a bidirectional DC / DC circuit. The first terminals of the first gating unit and the second gating unit are connected to the electrical signal of each battery cell in a battery pack, the second terminals of the first gating unit are connected to the first terminal of the bidirectional DC / DC circuit, and the second terminal of the bidirectional DC / DC circuit is connected to the second terminal of the second gating unit. During active balancing, the voltage of each battery cell is detected. During balancing, the first gating unit is controlled to conduct the electrical signal of the corresponding battery cell, and the second gating unit is controlled to conduct the total electrical signal between the first j strings of battery cells. Whether n battery cells in the battery pack are disconnected is detected by line sequence self-checking. If the disconnected battery cell is a high-order battery cell, the battery cell before the high-order battery cell is recorded as the jth battery cell, so as to automatically adjust the number of battery cell strings, so that the active balancing device can adapt to battery packs with different numbers of battery cells and has wide adaptability.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to active balancing in a battery pack. Background Art

[0002] Before active balancing, the battery will generally perform line sequence detection to determine whether the cells in the battery pack are working properly. When a cell fails, a fault alarm will generally be issued and the operation will stop.

[0003] In the prior art, active balancing circuits generally match the number of cells in a battery pack, and cannot achieve adaptive string numbers. Battery packs with different string numbers often need to use different active balancing circuits, which have narrow applicability and require a preset string number (for example, 12 strings need to be set) or cannot continue balancing when the string number changes or even disconnects. It is not smart and flexible enough. For example, during use, if a cell in the battery pack is disconnected, the active balancing module often stops working. Therefore, there is an urgent need for an active balancing module that can automatically adapt to lithium batteries with different string numbers. Summary of the invention

[0004] The object of the present invention is to provide an active balancing method and an active balancing device with adaptive number of battery cell strings, which can be adapted to battery packs with different numbers of strings and have wide adaptability.

[0005] In order to achieve the above-mentioned object, the present invention discloses an active balancing method with adaptive number of battery cell strings, which is used to control an active balancing circuit for balancing, wherein the active balancing circuit comprises a first gating unit, a second gating unit and a bidirectional DC / DC circuit, wherein the first terminals of the first gating unit and the second gating unit are connected to the electrical signal of each battery cell in a battery pack, the second terminals of the first gating unit are connected to the first terminal of the bidirectional DC / DC circuit, and the second terminal of the bidirectional DC / DC circuit is connected to the second terminal of the second gating unit; the battery pack has n battery cells connected in series in sequence, and the active balancing method comprises: when a balancing condition is met, controlling the first gating unit to conduct The electrical signal of the ith battery cell to be balanced is transmitted to the bidirectional DC / DC circuit; the second selection unit is controlled to conduct the total electrical signal between the 1st to the jth battery cells to the bidirectional DC / DC circuit; the bidirectional DC / DC circuit is controlled to balance the total voltage between the ith battery cell and the first j battery cells in series; it is detected whether the battery cells in the battery pack are offline, and if the offline battery cell is ranked behind all the online battery cells, the second selection unit is controlled to switch the conduction path from the positive electrical signal of the offline battery cell to the positive electrical signal of the highest ranked battery cell among the currently online battery cells, and j is the serial number of the highest ranked battery cell among the currently online battery cells.

[0006] Compared with the prior art, the present invention adds a second selection unit, which can select the number of strings of the total voltage during balancing, so that the active balancing is applicable to battery packs with different numbers of strings and has wide adaptability. Furthermore, when a high-position battery cell is disconnected, the present invention can timely adjust the number of balanced battery strings and the total output line of the battery, exclude the disconnected high-position battery cell, and select the second highest battery cell (the Jth battery cell) as the positive electrode of the balanced positive electrode and the positive electrode of the total voltage of the battery pack, so that the battery pack can continue to work.

[0007] Preferably, when the active balancing circuit is powered on, the first gating unit is controlled to switch on n cells in a time-division multiplexing manner, and the electrical signals of the n cells are correspondingly collected through the voltage collection circuit, and the indicating unit is controlled to indicate the abnormality when the electrical signal of any cell is abnormal, so that the staff can find the fault in time.

[0008] Preferably, before the voltage acquisition circuit collects the electrical signals of n cells, it is also determined whether the electrical signals of the cells are reversely connected, and if so, the polarity of the electrical signals of the cells is converted. This solution enables the polarity of the electrical signals of the cells to be adjusted in time when the electrical signals of the cells are reversely connected between the first selection unit or between the first selection unit and the line sequence detection module 41, without affecting subsequent detection control.

[0009] Preferably, a corresponding table of active balancing current preset values ​​and balancing voltage difference preset values ​​is also provided, wherein the balancing voltage difference is the maximum voltage difference of the battery pack. During each balancing, the active balancing current preset value is selected according to the voltage difference interval of the battery pack, and the PWM of the bidirectional DC / DC circuit is adjusted according to the active balancing current preset value to control the balancing current of active balancing. The smaller the value of the voltage difference interval of the battery pack, the smaller the active balancing current preset value. Through adaptive active balancing current adjustment, the consistency of the battery pack can be effectively balanced to within the preset voltage difference, avoiding voltage rebound after the large current balancing stops, and effectively improving the balancing effect.

[0010] Specifically, after each balancing is completed, it is also determined whether the battery group after balancing meets the balancing conditions. If so, secondary balancing is performed. During secondary balancing, the preset active balancing current value is adjusted according to the voltage difference of the current battery group until the preset active balancing current value reaches the preset minimum balancing current value, and then balancing is stopped. Balancing is stopped by the size of the preset active balancing current value, effectively avoiding invalid balancing, and because the preset active balancing current value is adjustable, it is convenient for the staff to adjust the balancing value.

[0011] Preferably, when the offline cell is ranked behind all online cells, the control indication unit indicates the abnormal situation and continues for a preset time. If the cell is still offline after the preset time, the second selection unit is controlled to switch the conduction path from the positive electrode electrical signal of the offline cell to the positive electrode electrical signal of the cell with the highest ranking among the current online cells. This eliminates the possibility of high-level cell offline caused by operator omission.

[0012] The present invention also discloses an active balancing device with adaptive number of battery cell strings, comprising an active balancing circuit and a control module, wherein the active balancing circuit comprises a first gating unit, a second gating unit and a bidirectional DC / DC circuit, wherein the first ends of the first gating unit and the second gating unit are connected to the two ends of each battery cell in a battery pack, the second end of the first gating unit is connected to the first end of the bidirectional DC / DC circuit, and the second end of the bidirectional DC / DC circuit is connected to the second end of the second gating unit; the battery pack has n battery cells connected in series in sequence, the control module comprises one or more processors, a memory and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by one or more processors, and the program comprises instructions for executing the active balancing method with adaptive number of battery cell strings as described above.

[0013] Preferably, the active balancing device also includes an operating unit, a power supply unit and a rechargeable battery, wherein the rechargeable battery supplies power to the power supply unit, and operating the operating unit can start the power supply unit. The power supply unit provides a preset constant voltage power supply to each unit in the active balancing circuit, and a unidirectional DC / DC circuit is provided between the second end of the second selection unit and the rechargeable battery so that the battery pack can charge the rechargeable battery.

[0014] Preferably, the active balancing device also includes a line sequence detection module, the input end of the line sequence detection module is connected to the second end of the first selection unit, the first selection unit selects to conduct the electrical signal of each battery cell in turn through time-division multiplexing, so that the line sequence detection module obtains the electrical signal of each battery cell in turn, the line sequence detection module converts the electrical signal of the battery cell into a corresponding detection signal and transmits it to the control module, and the control module determines whether the battery cell in the battery pack is offline based on the detection signal.

[0015] Specifically, the active balancing device also includes a polarity conversion unit and a voltage collection unit. The line sequence detection module compares the size of the positive lead wire signal and the negative lead wire signal of the battery cell, and outputs a valid positive connection signal when the positive lead wire signal of the battery cell is larger than the negative lead wire signal by a preset threshold value, and outputs a valid reverse connection signal when the negative lead wire signal of the battery cell is larger than the positive lead wire signal by a preset threshold value. The detection signal includes a valid positive connection signal and a valid reverse connection signal; the control module determines the connection status of the battery cell based on the valid positive connection signal and the valid reverse connection signal, and outputs a valid positive connection control signal when the battery cell is positively connected, and outputs a valid reverse connection control signal when the battery cell is reversely connected; the polarity conversion unit includes a first switch conversion circuit and a second switch conversion circuit, and the The first switch conversion circuit includes a first switch drive circuit, a switch circuit A and a switch circuit B, and the second switch conversion circuit includes a second switch drive circuit, a switch circuit C and a switch circuit D; the input end of the switch circuit A is connected to the positive electrode of the electrical signal of the battery cell currently selected by the first selection unit, the output end is connected to the positive electrode of the input end of the voltage acquisition unit, and the control end is connected to the output end of the first switch drive circuit; the input end of the switch circuit B is connected to the negative electrode of the electrical signal of the battery cell currently selected by the first selection unit, the output end is connected to the negative electrode of the input end of the voltage acquisition unit, and the control end is connected to the output end of the second switch drive circuit; the input end of the first switch drive circuit is connected to the positive control signal, and the switch circuit A and the switch circuit B are turned on when the effective positive control signal is received. ; The input end of the switch circuit C is connected to the negative pole of the electrical signal of the battery cell currently selected by the first selection unit, and the output end is connected to the positive pole of the input end of the voltage collection unit; the input end of the switch circuit D is connected to the positive pole of the electrical signal of the battery cell currently selected by the first selection unit, and the output end is connected to the negative pole of the input end of the voltage collection unit; the input end of the second switch drive circuit is connected to the effective reverse connection signal, and the switch circuit C and the switch circuit D are turned on when the effective reverse connection control signal is received; the voltage collection unit obtains the electrical signal of the battery cell through the positive pole and the negative pole of the input end, collects the voltage of the electrical signal and transmits the collected voltage to the control module. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram of the active balancing device with adaptive number of battery cell strings of the present invention.

[0017] Figure 2 This is the structure of the line sequence detection module of the present invention.

[0018] Figure 3 It is a structural diagram of the polarity conversion unit of the present invention. DETAILED DESCRIPTION

[0019] In order to explain the technical content, structural features, achieved objectives and effects of the present invention in detail, the following is a detailed description in conjunction with the implementation methods and the accompanying drawings.

[0020] refer to Figure 1 The present invention discloses an active balancing device 100 with adaptive number of battery cell strings, comprising an active balancing circuit and a control module 20, wherein the active balancing circuit comprises a first gating unit 11, a second gating unit 12 and a bidirectional DC / DC circuit 13, wherein the first terminals of the first gating unit 11 and the second gating unit 12 are connected to the two ends of each battery cell in a battery pack, the second terminal of the first gating unit 11 is connected to the first terminal of the bidirectional DC / DC circuit 13, and the second terminal of the bidirectional DC / DC circuit 13 is connected to the second terminal of the second gating unit 12; the battery pack has n battery cells connected in series in sequence.

[0021] The first gating unit 11 is a gating switch unit, with several MOS switches or small relay switches (including mechanical relays and photoelectric relays) SWAn as the core, and selects one of the n battery cell voltages through time-division multiplexing to be transmitted to the bidirectional DC / DC circuit 13 through buses CELL+ and CELL-, as an input signal or output signal of the bidirectional DC / DC circuit 13. The gating switch signal ENAn that controls the first gating unit 11 is controlled by the control module 20, and respectively selects the n battery cell voltages one by one.

[0022] The second gating unit 12 is a gating switch unit, with several MOS switches or small relay switches (including mechanical relays and photoelectric relays) SWAn as the core, and selects the total voltage channels corresponding to the different numbers of battery strings through the gating method, and selects the total voltage corresponding to the different numbers of battery strings to the bus signals VIN+ and VIN- as the input signal or output signal of the bidirectional DC / DC circuit 13. Its gating switch signal ENBn is controlled by the control module 20, and respectively selects the total voltage between the 1st string to the nth string of cells.

[0023] The control module 20 includes one or more processors, a memory and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by one or more processors, and the program includes instructions for executing an active balancing method for adaptively adjusting the number of battery cell strings.

[0024] Specifically, the control module 20 is based on MCU and embedded software, and includes necessary peripheral devices such as reference source, crystal oscillator, memory, logic circuit and buzzer, etc. Its basic hardware structure belongs to the well-known technology in the industry and will not be repeated. It collects the output current signal / input current signal IA of the bidirectional DC / DC circuit 13, and adjusts the PWM output of the duty cycle bidirectional DC / DC circuit 13 after calculation, so that the output current signal / input current signal IA current is the preset balancing current threshold. Its output signal SD can control the bidirectional DC / DC circuit 13 to select the discharge balancing or charge balancing mode.

[0025] Specifically, the active balancing method includes: during active balancing, detecting the voltage of each battery cell, and when the balancing condition is met, for example, when the i-th battery cell needs to be balanced, controlling the first selection unit 11 to conduct the electrical signals at both ends of the i-th battery cell Bi (the positive signal Bi+ of the battery cell lead wire and the negative signal Bi- of the battery cell lead wire), controlling the second selection unit 12 to conduct the total electrical signal B0-Bj between the 1st to the j-th battery cells (the second selection unit 12 respectively conducts the paths corresponding to the battery cell lead wire B0 and the battery cell lead wire Bj), and controlling the bidirectional DC / DC circuit 13 to perform corresponding discharge balancing or charge balancing (starting discharge balancing when the power of the i-th battery cell is too large, and starting charge balancing when the power of the i-th battery cell is too small), so that the i-th battery cell Bi is connected to the battery cell Bi+, and the battery cell Bi is connected to the battery cell Bi+, and the battery cell Bi is connected to the battery cell Bi-. The battery cell Bi is balanced with the total voltage B0-Bj formed by the 1st to jth battery cells; the line sequence self-check is used to detect whether the n battery cells B1-Bn in the battery pack are offline; if the offline battery cell is arranged in the battery pack at the rear side of all the currently online battery cells (at a high position), the battery cell arranged at the end of the team among the online battery cells is recorded as the jth battery cell, and the second selection unit 12 is controlled to switch the conduction path from the positive electrical signal of the offline battery cell to the positive electrical signal of the battery cell with the highest ranking among the currently online battery cells (the second selection unit 12 turns on the battery cell lead line Bj), so as to adjust the second selection unit 12 to turn on the total electrical signal B0-Bj between the 1st to the new jth battery cell during active balancing (this is the adaptive string number switching function). For example, the current battery pack has 16 cells. If the 16th battery is offline, the second selection unit 12 is controlled to conduct the total electrical signal B0-B15 between the negative electrode of the first cell (cell lead wire B0 is turned on) and the positive electrode of the 15th cell (cell lead wire B15 is turned on), and the total electrical signal B0-B15 between the 1st to 15th cells is used as the balanced total voltage application, power supply voltage output, and charging bus. j is greater than or equal to 1 and less than or equal to i, i=1, 2, 3...n, and n is an integer greater than or equal to 2.

[0026] Among them, the second selection unit 12 is used to conduct the total negative electrode and the total positive electrode of the battery pack (i.e., the battery bus of the battery pack), which is used for discharging, charging and balancing of the battery pack. In the present invention, the total negative electrode of the battery pack is the negative electrode of the fixed first battery cell B1, so the lead wire B0 of the total negative electrode of the battery pack (the lead wire connected to the negative electrode of the first battery cell B1) can be fixedly connected to the second end of the bidirectional DC / DC circuit 13, or the lead wire B0 of the total negative electrode of the battery pack can be connected to the second end of the bidirectional DC / DC circuit 13 through the second selection unit 12. The total positive electrode of the battery pack is a path that can be selected by the second selection unit 12, so the first end of the second selection unit 12 is respectively connected to the lead wires B1...Bn of the positive electrodes of the 1st to nth battery cells, so that the lead wires B1...Bn are selected to be conducted to the second end of the bidirectional DC / DC circuit 13, and the second selection unit 12 selects the positive electrode of the jth battery cell Bj (conducting the battery cell lead wire Bj) as the total positive electrode of the battery pack, that is, the positive bus.

[0027] The control module 20 controls the balancing mode of the bidirectional DC / DC circuit 13 through the control signal SD.

[0028] Among them, the lead wire of the total negative electrode of the battery pack is B0, and the electrical signal output by the positive electrode transmission line of the i-th battery cell is Bi, so the battery pack is connected to the first selection unit 11 (the second selection unit 12) through n+1 battery cell wires to respectively connect the battery cell lead wires B0, B1...Bn, among which the positive electrode signal Bi+ of the battery cell lead wire output by the i-th battery cell corresponds to the battery cell lead wire Bi, and the negative electrode signal Bi+ of the battery cell lead wire corresponds to the battery cell lead wire B(i-1), for example, when the first selection unit 11 switches to output the electrical signals B1+ and B1- of the first battery cell, the first selection unit 11 turns on the switches corresponding to the battery cell lead wires B1 and the battery cell lead wires B0. Among them, since the battery cell lead wires may be reversely connected, when the two battery cell lead wires of a certain battery cell are reversely connected, the negative electrode signal Bi+ of the battery cell lead wire is actually the positive electrode signal of the battery cell, and the positive electrode signal Bi+ of the battery cell lead wire is actually the negative electrode signal of the battery cell.

[0029] Preferably, in the active balancing method, when the active balancing circuit is powered on, the electrical signals of the n cells in the battery pack are detected in real time through line sequence self-checking, and the control module 20 controls the indicating unit 21 to indicate the abnormal situation when the electrical signal of any of the cells is abnormal. The indicating unit 21 is a display screen or an indicator light. The control module 20 collects the electrical signal of the cell Bi selected by the first selection unit 11 through the voltage collection unit 42.

[0030] Preferably, the positive and negative poles of the electric signal of the battery cell are detected. If the positive and negative poles of the battery cell are detected to be reversed first, so that the electric signal of the battery cell is reversed, the polarity of the electric signal of the battery cell is converted. The electric signal of the selected battery cell is obtained by the line sequence detection module and transmitted to the polarity conversion unit 43, and the polarity of the electric signal of the reversed battery cell is converted by the polarity conversion unit 43, and the negative pole signal of the electric signal of the battery cell is transmitted to the positive input terminal of the voltage acquisition circuit, and the positive pole signal of the electric signal of the battery cell is transmitted to the negative input terminal of the voltage acquisition circuit.

[0031] Preferably, in the active balancing method, when the active balancing is started, the control module is also pre-set with a corresponding table of active balancing current preset values ​​and balancing voltage difference preset values, the balancing voltage difference is the maximum voltage difference of the battery pack, and each time the balancing is performed, the active balancing current preset value is selected according to the voltage difference interval of the battery pack, and the PWM of the bidirectional DC / DC circuit is adjusted according to the active balancing current preset value to control the balancing current of the active balancing. The smaller the value of the voltage difference interval of the battery pack is, the smaller the active balancing current preset value is. The control module 20 transmits a control signal PWM to the bidirectional DC / DC circuit to control the balancing current of the active balancing.

[0032] Among them, after each balancing is completed, it is also determined whether the balanced battery group meets the balancing conditions. If so, secondary balancing is performed. During the secondary balancing, the active balancing current preset value is adjusted according to the current voltage difference of the battery group until the active balancing current preset value reaches the preset minimum balancing current value, then the balancing is stopped.

[0033] When the voltage difference of the battery pack of the control module 20 is greater than or equal to the preset value, active balancing is started, otherwise active balancing is stopped. In this embodiment, active balancing is started when the voltage difference of the battery pack is ≥5mV, for example. Of course, the preset value of the battery pack voltage difference comparison is not limited to the above value.

[0034] The control module 20 controls the first selection unit 11, the line sequence detection module 41 and the voltage acquisition unit 42 to perform line sequence self-check at a certain period to determine whether each cell in the battery pack is faulty, whether the cell is disconnected, and whether the battery pack meets the balancing condition. The line sequence self-check is automatically started after power-on.

[0035] In this embodiment, the preset value of the active balancing current is configured and adjusted through the operation unit 301 and the indication unit 21. For example, in one embodiment, the preset value of the active balancing current is 1-10A, and the preset value of the balancing voltage difference is (for example, 5mV to 1000mV). During the balancing process, the size of the active balancing current can be adaptively adjusted according to the voltage difference of the battery pack. For example, the initial balancing current is 10A. When the first active balancing stops, if it is determined that the balancing condition is met, the balancing can be started and continued. The current of the second balancing is automatically halved (rounded up), for example, 5A; and so on. The third active balancing current is 3A (2.5 is rounded up to 3); ..., until the minimum balancing current value is 1A. By adaptively adjusting the active balancing current, the consistency of the battery pack can be effectively balanced to within the preset voltage difference, avoiding the voltage rebound after the large current balancing stops, and effectively improving the balancing effect.

[0036] Preferably, when the offline battery cell is ranked at the rear of all online battery cells, the control indication unit indicates the abnormal situation and lasts for a preset time. If the battery cell is still offline after the preset time, the second selection unit is controlled to switch the conduction path from the positive electrical signal of the offline battery cell to the positive electrical signal of the highest ranked battery cell among the currently online battery cells.

[0037] For example, during active balancing, when a high-string battery (a battery cell arranged in the battery pack at the rear of all currently online batteries) is offline, such as B16, and B16 is detected offline, a fault prompt will be given first (for example, for 5 seconds). If the fault prompt time is exceeded and the fault is not handled, an intelligent self-check will be automatically performed, and the second-lowest string battery channel B15 will be switched to VIN+ for active balancing, thereby achieving adaptive string switching. And so on.

[0038] When the adaptive string number switching function is not needed, the control module 20 can configure fixed string number detection and balancing through the operation unit 301 and the indication unit 21. Alternatively, the second selection unit 12 is cancelled, VIN+ is fixed to the highest voltage position of the n-string battery, such as B16, and VIN- is fixed to the lowest voltage position of the n-string battery, such as B0.

[0039] Preferably, the active balancing device 100 further includes an operation unit 301, a power supply unit 302 and a rechargeable battery 303. The operation unit 301 can be operated to start the power supply unit 302, and the power supply unit 302 provides a preset constant voltage power supply to each module in the active balancing circuit. A unidirectional DC / DC circuit 304 is provided between the second end of the second gating unit 12 and the rechargeable battery 303 so that the battery pack can charge the rechargeable battery 303, and the rechargeable battery 303 supplies power to the power supply unit 302. The unidirectional DC / DC circuit 304 is controlled by a control signal of the control module 20, and can charge the rechargeable battery 303 with a constant voltage and a constant current after reducing the voltage of VIN+ / VIN-.

[0040] The rechargeable battery 303 is a built-in battery. Of course, the rechargeable battery 303 can also be replaced by a non-rechargeable primary battery.

[0041] Preferably, the active balancing device 100 further includes a USB charging unit 305, which converts the USB voltage (usually 5V) into a constant voltage and constant current charging unit for the rechargeable battery 303. The voltage supply range of the USB can be up to 48V. The rechargeable battery 303 and the unidirectional DC / DC circuit 304 can exist at the same time or separately.

[0042] The power supply unit 302 is based on a BCUK circuit, an LDO circuit or a flyback circuit to provide a suitable working voltage for system related units. Preferably, the power supply unit 302 can be controlled by the operation unit 301 for output and is also latched by the control module 20 to realize the system delayed power-off function.

[0043] The operation unit 301 is composed of m (m≥1) buttons, one ON / OFF button can control the power supply unit 302 to power on or off, and the remaining buttons are used to realize the up, down, confirm or cancel selection functions.

[0044] refer to Figure 1 The active balancing device 100 also includes a line sequence detection module 41, the input end of the line sequence detection module 41 is connected to the second end of the first selection unit 11, and the first selection unit 11 selects to conduct the voltages at both ends of each battery cell in turn through time-division multiplexing, so that the line sequence detection module 41 obtains the electrical signal of each battery cell in turn, and the line sequence detection module 41 converts the electrical signal of the battery cell into corresponding high and low level detection signals V1 and V2 and transmits them to the control module 20. The control module 20 determines whether the battery cells in the battery pack are disconnected, connected properly, etc. according to the detection signals V1 and V2.

[0045] Among them, the line sequence detection module 41 compares the size of the positive lead wire signal Bi+ and the negative lead wire signal Bi- of the battery cell Bi, and outputs a valid positive connection signal when the positive lead wire signal Bi+ of the battery cell Bi is larger than the negative lead wire signal Bi- by a preset threshold, and outputs a valid reverse connection signal when the negative lead wire signal Bi- is larger than the positive lead wire signal Bi+ by a preset threshold. The detection signal includes a valid positive connection signal V1 and a valid reverse connection signal V2.

[0046] Among them, the control module 20 also determines the wiring conditions of the battery cell lead wires in the battery pack based on the detection signals V1 and V2 to output corresponding positive control signals VS1 and reverse control signals VS2, wherein a valid positive control signal VS1 is output when the battery cell lead wires are positively connected, and a valid reverse control signal VS2 is output when the battery cell lead wires are reversely connected.

[0047] refer to Figure 2 The line sequence detection module 41 includes a first comparison circuit and a second comparison circuit.

[0048] refer to Figure 2 The first comparison circuit includes a first voltage-dividing starting circuit 311 and a positive switch circuit 321. The control end of the positive switch circuit 321 is connected to the output end of the first voltage-dividing starting circuit 311, the input end of the positive switch circuit 321 is connected to a constant voltage signal VDD, and the output end of the positive switch circuit 321 outputs a valid positive signal V1. The first voltage-dividing starting circuit 311 divides the voltage difference between the positive signal Bi+ and the negative signal Bi- into a first voltage-dividing driving voltage and transmits it to the control end of the positive switch circuit 321, so that the positive switch circuit 321 is turned on when the first voltage-dividing driving voltage is greater than the starting voltage of the positive switch circuit 321, so that the positive switch circuit 321 outputs the constant voltage signal VDD as a valid positive signal V1.

[0049] The first voltage-dividing startup circuit 311 is composed of a plurality of resistors and a unidirectional conducting diode ZD1, including a voltage-dividing circuit in which a plurality of resistors are connected in series between the positive signal Bi+ and the negative signal Bi-, and a unidirectional conducting diode ZD1 connected in series with the voltage-dividing circuit, wherein the unidirectional conducting diode ZD1 is conducted from the positive signal Bi+ to the negative signal Bi-, and the first voltage-dividing startup circuit 311 divides the voltage difference between the positive signal Bi+ and the negative signal Bi- in a corresponding proportion and outputs it to the positive switch circuit 321. The positive switch circuit 321 is composed of a plurality of switch tubes (such as MOS tubes, triodes), resistors, and unidirectional conducting diodes, and is a switch circuit that is driven to conduct when subjected to corresponding high and low levels.

[0050] refer to Figure 2The second comparison circuit includes a second voltage-dividing starting circuit 312 and a reverse switch circuit 322, wherein the control end of the reverse switch circuit 322 is connected to the output end of the second voltage-dividing starting circuit 312, the input end of the reverse switch circuit 322 is connected to a constant voltage signal VDD, and the output end of the reverse switch circuit 322 outputs a valid reverse signal V2. The second voltage-dividing starting circuit 312 divides the voltage difference between the negative signal Bi- and the positive signal Bi+ into a second voltage-dividing driving voltage and transmits it to the control end of the reverse switch circuit 322, thereby turning on the reverse switch circuit 322 when the second voltage-dividing driving voltage is greater than the starting voltage of the reverse switch circuit 322, so that the output end of the reverse switch circuit 322 outputs the constant voltage signal VDD as the valid reverse signal V2.

[0051] The second voltage-dividing startup circuit 312 is composed of a plurality of resistors and a unidirectional conducting diode ZD2, including a voltage-dividing circuit in which a plurality of resistors are connected in series between the negative signal Bi- and the positive signal Bi+, and a unidirectional conducting diode ZD2 connected in series with the voltage-dividing circuit, wherein the unidirectional conducting diode ZD2 is conducted from the negative signal Bi- to the positive signal Bi+, and the second voltage-dividing startup circuit 312 divides the voltage difference between the negative signal Bi- and the positive signal Bi+ according to a corresponding ratio and outputs it to the reverse switch circuit 322. The reverse switch circuit 322 is composed of a plurality of switch tubes (such as MOS tubes, triodes), resistors, and unidirectional conducting diodes, and is a switch circuit that is driven to conduct when subjected to corresponding high and low levels.

[0052] The control module 20 determines whether the battery cell is disconnected, over-voltaged, or reversely connected through the detection signal V1 and the detection signal V2.

[0053] refer to Figure 3 The active balancing device 100 also includes a voltage acquisition unit 42 and a polarity conversion unit 43. The polarity conversion unit 43 includes two switch conversion circuits with the same structure, wherein one switch conversion circuit includes a switch drive circuit 431, a switch circuit A and a switch circuit B, and the other switch conversion circuit includes a switch drive circuit 432, a switch circuit C and a switch circuit D.

[0054] refer to Figure 3 The control end of the switch driving circuit 431 is connected to the positive control signal VS1, and the control end of the switch driving circuit 432 is connected to the reverse control signal VS2. The positive control signal VS1 and the reverse control signal VS2 are control signals with opposite high and low levels. They are control signals output by the control module 20 based on whether the lead wire of the corresponding battery cell Bi is positively connected.

[0055] refer to Figure 3The input end of the switch circuit A is connected to the positive signal Bi+ of the cell lead wire of the cell Bi currently selected by the first selection unit 11, and the output end is connected to the input end V0+ of the voltage collection unit 42. The input end of the switch circuit B is connected to the negative signal Bi+ of the cell lead wire of the cell Bi currently selected by the first selection unit 11, and the output end is connected to the input end V0- of the voltage collection unit 42. When the cell Bi is positively connected, the switch drive circuit 431 turns on the switch circuit A and the switch circuit B according to the effective positive connection control signal VS1. When the cell Bi is reversely connected or disconnected, the switch drive circuit 431 cannot receive the effective positive connection control signal VS1 and disconnects the switch circuit A and the switch circuit B. The input end of the switch circuit C is connected to the negative signal Bi+ of the cell lead wire of the battery cell Bi currently selected by the first selection unit 11, and the output end is connected to the input end V0+ of the voltage collection unit 42. The input end of the switch circuit D is connected to the positive signal Bi+ of the cell lead wire of the battery cell Bi currently selected by the first selection unit 11, and the output end is connected to the input end V0- of the voltage collection unit 42. When the battery cell Bi is reversely connected, the switch drive circuit 431 turns on the switch circuit C and the switch circuit D according to the effective reverse control signal VS2. When the battery cell Bi is positively connected or disconnected, the switch drive circuit 431 disconnects the switch circuit C and the switch circuit D.

[0056] The input ends of switch circuit A and switch circuit B are respectively provided with a unidirectional conducting diode, which are connected in parallel and then connected to the output end of switch driving circuit 431. The input ends of switch circuit C and switch circuit D are respectively provided with a unidirectional conducting diode, which are connected in parallel and then connected to the output end of switch driving circuit 432.

[0057] Among them, the switch drive circuits 431 and 432 are voltage conversion circuits, and the first switch drive circuit 431 and the second switch drive circuit 432 have the same structure, and are composed of a voltage divider circuit connected in series between the control signal and the ground. The switch circuit C and the switch circuit D are composed of one or more switch tubes and some necessary basic components (resistors, diodes). In this embodiment, the effective detection signal is a high-level signal. When the effective detection signal is a low-level signal, the first switch drive circuit 431 and the second switch drive circuit 432 are composed of a voltage divider circuit connected in series between a constant high level and the control signal.

[0058] If the currently selected cell Bi is positively connected, the control module 20 controls VS1 to be high level, VS2 to be low level, the switch drive circuit connected to VS1 drives the corresponding switch circuit to be turned on, and the switch drive circuit connected to VS2 drives the corresponding switch circuit to be turned off, so that Bi+ is delivered to V0+ and Bi- is delivered to V0-. If the currently selected cell Bi is reversely connected, the control module 20 controls VS1 to be low level, VS2 to be high level, the switch drive circuit connected to VS1 drives the corresponding switch circuit to be turned off, and the switch drive circuit connected to VS2 drives the corresponding switch circuit to be turned on, so that Bi+ is delivered to V0- and Bi- is delivered to V0+.

[0059] Of course, the high and low level settings of VS1 and VS2 are not limited to the above embodiments. When the battery cell Bi is positively connected, VS1 can be controlled to be a low level and VS2 to be a high level. The switch driving circuit connected to VS1 drives the corresponding switch circuit to be turned on, and the switch driving circuit connected to VS2 drives the corresponding switch circuit to be turned off; when the battery cell Bi is reversely connected, VS1 can be controlled to be a high level and VS2 to be a low level. The switch driving circuit connected to VS1 drives the corresponding switch circuit to be turned off, and the switch driving circuit connected to VS2 drives the corresponding switch circuit to be turned on.

[0060] Preferably, the line sequence detection module 41 also has an overvoltage protection function. When the voltage difference caused by the reverse connection of the line sequence is large, the detection signals V1 and V2 transmitted to the control module 20 are invalid. At this time, VS1 and VS2 are invalid control signals, which are control signals that disconnect the switch circuit A, switch circuit B, switch circuit C, and switch circuit D, thereby preventing the voltage acquisition unit 42 from collecting excessive voltage and causing damage. Among them, when a certain battery cell is disconnected, the control module 20 correspondingly outputs invalid control signals VS1 and VS2 to control the switch circuit A, switch circuit B, switch circuit C, and switch circuit D to disconnect, and the voltage acquisition unit 42 does not collect the voltage of the battery cell.

[0061] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention are still within the scope covered by the present invention.

Claims

1. An active balancing method with adaptive number of battery cell strings, used to control an active balancing circuit for balancing, characterized in that: The active balancing circuit comprises a first gating unit, a second gating unit and a bidirectional DC / DC circuit, wherein the first terminals of the first gating unit and the second gating unit are connected to the electrical signal of each battery cell in the battery pack, the second terminal of the first gating unit is connected to the first terminal of the bidirectional DC / DC circuit, and the second terminal of the bidirectional DC / DC circuit is connected to the second terminal of the second gating unit; the battery pack has n battery cells connected in series in sequence, and the active balancing method comprises: When the balancing condition is met, the first gating unit is controlled to conduct the electrical signal of the i-th battery cell to be balanced to the bidirectional DC / DC circuit; the second gating unit is controlled to conduct the total electrical signal between the 1st to the j-th battery cells to the bidirectional DC / DC circuit; the bidirectional DC / DC circuit is controlled to balance the total voltage between the i-th battery cell and the first j battery cells connected in series; Detect whether the battery cell in the battery pack is offline. If the offline battery cell is ranked behind all the online battery cells, control the second selection unit to switch the conduction path from the positive electrical signal of the offline battery cell to the positive electrical signal of the highest ranked battery cell among the currently online battery cells. At this time, j is the serial number of the highest ranked battery cell among the currently online battery cells.

2. The method for active balancing with adaptive number of battery strings as claimed in claim 1, characterized in that: When the active balancing circuit is powered on, the first selection unit is controlled to switch on n battery cells in a time-division multiplexing manner, the electrical signals of the n battery cells are correspondingly collected through the voltage collection circuit, and the indication unit is controlled to indicate the abnormal situation when the electrical signal of any of the battery cells is abnormal.

3. The method for active balancing with adaptive number of battery strings as claimed in claim 2, characterized in that: Before the voltage collection circuit collects the electrical signals of the n battery cells, it is also determined whether the electrical signals of the battery cells are reversely connected. If so, the polarity of the electrical signals of the battery cells is reversed.

4. The method for active balancing with adaptive number of battery strings as claimed in claim 1, characterized in that: A correspondence table of active balancing current preset values ​​and balancing voltage difference preset values ​​is also provided. The balancing voltage difference is the maximum voltage difference of the battery pack. During each balancing, the active balancing current preset value is selected according to the voltage difference interval of the battery pack. The PWM of the bidirectional DC / DC circuit is adjusted according to the active balancing current preset value to control the balancing current of active balancing. The smaller the value of the voltage difference interval of the battery pack is, the smaller the active balancing current preset value is.

5. The method for active balancing with adaptive number of battery strings as claimed in claim 4, characterized in that: After each balancing is completed, it is also determined whether the balanced battery group meets the balancing conditions. If so, secondary balancing is performed. During secondary balancing, the active balancing current preset value is adjusted according to the current voltage difference of the battery group until the active balancing current preset value reaches the preset minimum balancing current value, then balancing is stopped.

6. The method for adaptive active balancing of the number of battery strings as claimed in claim 1, characterized in that: When the offline battery cell is ranked behind all the online battery cells, the control indication unit indicates the abnormal situation and lasts for a preset time. If the battery cell is still offline after the preset time, the second selection unit will be controlled to switch the conduction path from the positive electrical signal of the offline battery cell to the positive electrical signal of the highest ranked battery cell among the currently online battery cells.

7. An active balancing device with adaptive number of battery strings, characterized in that: It comprises an active balancing circuit and a control module, wherein the active balancing circuit comprises a first gating unit, a second gating unit and a bidirectional DC / DC circuit, wherein the first terminals of the first gating unit and the second gating unit are connected to the two terminals of each battery cell in the battery pack, the second terminal of the first gating unit is connected to the first terminal of the bidirectional DC / DC circuit, and the second terminal of the bidirectional DC / DC circuit is connected to the second terminal of the second gating unit; the battery pack has n battery cells connected in series in sequence, and the control module comprises one or more processors, a memory and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by one or more processors, and the program comprises instructions for executing an active balancing method for adaptive active balancing of the number of battery cell strings as described in any one of claims 1 to 6.

8. The active balancing device with adaptive number of battery cell strings as claimed in claim 7, characterized in that: It also includes an operating unit, a power supply unit and a rechargeable battery, wherein the rechargeable battery supplies power to the power supply unit, and the power supply unit can be started by operating the operating unit. The power supply unit provides a preset constant voltage power supply to each unit in the active balancing circuit, and a unidirectional DC / DC circuit is provided between the second end of the second selection unit and the rechargeable battery so that the battery pack can charge the rechargeable battery.

9. The active balancing device with adaptive number of battery cell strings as claimed in claim 7, characterized in that: It also includes a line sequence detection module, the input end of the line sequence detection module is connected to the second end of the first selection unit, the first selection unit selects to conduct the electrical signal of each battery cell in turn through time-division multiplexing, so that the line sequence detection module obtains the electrical signal of each battery cell in turn, the line sequence detection module converts the electrical signal of the battery cell into a corresponding detection signal and transmits it to the control module, and the control module determines whether the battery cell in the battery pack is offline based on the detection signal.

10. The active balancing device with adaptive number of battery cell strings as claimed in claim 9, characterized in that: It also includes a polarity conversion unit and a voltage acquisition unit, wherein the line sequence detection module compares the size of the positive lead wire signal and the negative lead wire signal of the battery cell, outputs a valid positive connection signal when the positive lead wire signal of the battery cell is larger than the negative lead wire signal by a preset threshold, and outputs a valid reverse connection signal when the negative lead wire signal of the battery cell is larger than the positive lead wire signal by a preset threshold, and the detection signal includes a valid positive connection signal and a valid reverse connection signal; The control module determines the connection state of the battery cell according to the effective positive connection signal and the effective reverse connection signal, outputs an effective positive connection control signal when the battery cell is positively connected, and outputs an effective reverse connection control signal when the battery cell is reversely connected; The polarity conversion unit includes a first switch conversion circuit and a second switch conversion circuit, the first switch conversion circuit includes a first switch drive circuit, a switch circuit A and a switch circuit B, and the second switch conversion circuit includes a second switch drive circuit, a switch circuit C and a switch circuit D; The input end of the switch circuit A is connected to the positive electrode of the electric signal of the cell currently selected by the first selection unit, the output end is connected to the positive electrode of the input end of the voltage acquisition unit, and the control end is connected to the output end of the first switch driving circuit; the input end of the switch circuit B is connected to the negative electrode of the electric signal of the cell currently selected by the first selection unit, the output end is connected to the negative electrode of the input end of the voltage acquisition unit, and the control end is connected to the output end of the second switch driving circuit; the input end of the first switch driving circuit is connected to the positive control signal, and the switch circuit A and the switch circuit B are turned on when receiving the valid positive control signal; The input end of the switch circuit C is connected to the negative pole of the electric signal of the cell currently selected by the first selection unit, and the output end is connected to the positive pole of the input end of the voltage collection unit. The input end of the switch circuit D is connected to the positive pole of the electric signal of the cell currently selected by the first selection unit, and the output end is connected to the negative pole of the input end of the voltage collection unit. The input end of the second switch driving circuit is connected to the effective reverse connection signal, and the switch circuit C and the switch circuit D are turned on when the effective reverse connection control signal is received; The voltage acquisition unit acquires the electrical signal of the battery cell through the positive input terminal and the negative input terminal, acquires the voltage of the electrical signal and transmits the acquired voltage to the control module.

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