Double-layer active equalization circuit, energy storage system and battery management system

Abstract

The utility model provides a double-layer active equalization circuit, an energy storage system and a battery management system. The circuit comprises a first-layer equalization unit corresponding to a battery unit, a second-layer equalization module and a selection driving module, three ends of the first-layer balancing unit are respectively coupled with two ends of the corresponding battery unit and a first node between the single battery cells; two ends and N-1 third ends of the second-layer equalization module are respectively coupled with the first end of the head-end battery unit, the second end of the tail-end battery unit and N-1 second nodes; and the control ends of the first-layer balancing unit and the second-layer balancing module are coupled with the selection driving module. And the selection driving module drives the first-layer balancing unit to carry out voltage balancing on the single battery cells according to the first driving control signal and drives the second-layer balancing module to carry out voltage balancing on the battery cells according to the second driving control signal. And the efficiency and the equalization speed of active equalization can be obviously improved.

Description

Technical Field

[0001] The utility model relates to the technical field of battery management, and in particular to a double-layer active balancing circuit, an energy storage system and a battery management system. Background Art

[0002] With the rapid development of new energy and energy storage technologies, lithium batteries are widely used due to their high energy density, long service life, and green environmental protection. Since the voltage and capacity of a single cell are very small, it is difficult to meet the actual power demand. Usually, multiple cells are connected in series or in parallel to form a large lithium battery energy storage system so that the lithium battery can have a sufficiently large voltage, capacity, and power. However, in this large energy storage system, since the characteristics of each cell cannot be completely consistent, some cells often overcharge or over-discharge, affecting the battery's service life and maximum capacity utilization. In severe cases, it may even cause thermal runaway of the battery and cause a fire. Therefore, battery balancing technology is particularly important in battery management systems.

[0003] The current mainstream battery balancing technologies can be divided into two categories. One of them is to dissipate the excess power of the single cell in the form of heat through bypass resistance to achieve the purpose of balancing. This balancing method is called passive balancing. The advantages of passive balancing are simple circuit structure and easy implementation, but passive balancing has the disadvantages of low balancing efficiency and large energy loss. The other is to use energy storage elements as intermediate carriers to transfer the charge of the single cell with higher power to the single cell with lower power. Since active balancing has no energy loss under ideal conditions, it can improve the efficiency of balancing compared to passive balancing. More specifically, active balancing energy storage elements can be divided into four categories according to their types, namely switched capacitor balancing circuits, inductor balancing circuits, switched power supply balancing circuits and transformer balancing circuits. The switched capacitor balancing circuit achieves the transfer of electricity based on the voltage difference between single cells. When the voltage difference is small, the balancing speed is low and effective balancing cannot be achieved. Although the inductor balancing does not use the voltage difference to achieve balancing, it can only achieve balancing between two adjacent single cells. For large battery packs with a large number of series connections, the balancing time is longer. The control of the switching power supply balancing circuit is relatively complex. Transformer balancing is less used due to the relatively large size of the transformer.

[0004] It should be noted that the information disclosed in the background technology section of the utility model is only intended to deepen the understanding of the general background technology of the utility model, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Utility Model Content

[0005] The purpose of the utility model is to provide a double-layer active balancing circuit, energy storage system and battery management system to address one or more of the problems of low balancing efficiency, long balancing time and complex control in the battery balancing circuit in the prior art. The utility model not only has the advantages of switched capacitor and inductor balancing, can significantly improve the efficiency and balancing speed of active balancing, but also is easy to control and implement.

[0006] In order to achieve the above object, the utility model is implemented by the following technical solutions: a double-layer active balancing circuit, used in a battery management system, the battery management system is used to manage N battery cells connected in series, each of the battery cells includes two single cells connected in series, the double-layer active balancing circuit includes: a first-layer balancing module, a second-layer balancing module and a selection drive module, wherein N≥2, the first-layer balancing module includes N first-layer balancing units corresponding to the battery cells one by one;

[0007] The first end, the second end and the third end of the first-layer balancing unit are respectively coupled to the first end, the second end and the first nodes of the two single cells of the battery unit corresponding thereto, and the control end of the first-layer balancing unit is coupled to the selection driving module; the first end, the second end and N-1 third ends of the second-layer balancing module are respectively coupled to the first end of the battery unit at the head end, the second end of the battery unit at the tail end and N-1 second nodes of the N battery units; the control end of the second-layer balancing module is coupled to the selection driving module;

[0008] The selection drive module is configured to drive the first layer balancing module to perform voltage balancing on the single cells of all the battery cells according to the received first drive control signal, and to drive the second layer balancing module to perform voltage balancing on the two battery cells selected by the second drive control signal according to the received second drive control signal.

[0009] Optionally, the first-layer balancing unit includes a first switch tube, a second switch tube and a first energy storage unit; the first end of the first switch tube is coupled to the negative electrode of the battery unit corresponding thereto, the second end of the first switch tube and the first end of the second switch tube are coupled to the first end of the first energy storage unit, the second end of the first energy storage unit is coupled to the first node, the second end of the second switch tube is coupled to the positive electrode of the battery unit, and the control end of the first switch tube and the control end of the second switch tube are respectively coupled to the selection drive module;

[0010] The selection driving module is configured to drive the first switch tubes and the second switch tubes of all the first-layer balancing units to be alternately turned on and off according to the first driving control signal.

[0011] Optionally, the first energy storage unit includes an inductor.

[0012] Optionally, the first drive control signal includes a set of complementary switch tube control signals, and the microcontroller of the battery management system includes a first pin and a second pin for transmitting the switch tube control signal; the selection drive module includes at least one first layer drive unit, and the first layer drive unit includes a first drive circuit and a first pulse transformer and a second pulse transformer each having two secondary windings;

[0013] The first input terminal of the first driving circuit is coupled to the first pin, the second input terminal of the first driving circuit is coupled to the second pin, the two output terminals of the first driving circuit are respectively coupled to the primary winding of the first pulse transformer and the primary winding of the second pulse transformer, and the first driving circuit is configured to generate a pair of complementary first driving signals according to the switch tube control signal;

[0014] The two secondary windings of the first pulse transformer are respectively coupled to the control ends of the first switching tubes of any two first-layer balancing units corresponding to the first drive circuit to transmit one of the first drive signals; the two secondary windings of the second pulse transformer are respectively coupled to the control ends of the second switching tubes of the two first-layer balancing units to transmit the other first drive signal.

[0015] Optionally, the second-layer balancing module includes a second-layer balancing unit and a second energy storage unit corresponding to the battery cells one by one, the first end and the second end of the second-layer balancing unit are respectively coupled to the negative electrode and the positive electrode of the corresponding battery cell, the third end and the fourth end of all the second-layer balancing units are respectively coupled to the first end and the second end of the second energy storage unit, and the control ends of all the second-layer balancing units are respectively coupled to the selection drive module;

[0016] The selection driving module is configured to drive the second-layer balancing units corresponding to the two battery cells selected by the second driving control signal to be alternately turned on and off according to the second driving control signal, and continuously control the other second-layer balancing units to remain in an off state during the alternating turning on and off process.

[0017] Optionally, the second-layer balancing unit includes a third switch tube and a fourth switch tube, the first end of the third switch tube is coupled to the negative electrode of the corresponding battery cell, the first end of the fourth switch tube is coupled to the positive electrode of the battery cell, the second end of the third switch tube is coupled to the first end of the second energy storage unit, the second end of the fourth switch tube is coupled to the second end of the second energy storage unit, and the control end of the third switch tube and the control end of the fourth switch tube are respectively coupled to the selection drive module.

[0018] Optionally, the second energy storage unit includes a capacitor.

[0019] Optionally, the microcontroller of the battery management system includes a third pin and at least three address pins for transmitting the second drive control signal; the selection drive module also includes a multiplexing circuit and at least one second-layer drive unit, the signal input end of the multiplexing circuit is coupled to the third pin, and the three channel selection pins of the multiplexing circuit are respectively coupled to the three address pins in a one-to-one correspondence; every two output ends of the multiplexing circuit are respectively coupled to two input ends of one of the second-layer drive units, and the output ends of the second-layer drive units are respectively coupled to the control ends of any two corresponding second-layer balancing units;

[0020] The multiplexing circuit is configured to drive one of the second-layer balancing units selected by the second driving control signal to turn on according to the second driving control signal, and to turn off the other second-layer balancing units.

[0021] Optionally, the second-layer driving unit includes a second driving circuit and a third pulse transformer and a fourth pulse transformer each having two secondary windings; the two input ends of the second driving circuit are respectively coupled to two output ends of the multiplexing circuit, one of the output ends of the second driving circuit is coupled to the primary winding of the third pulse transformer, and the other output end of the second driving circuit is coupled to the primary winding of the fourth pulse transformer; the two secondary windings of the third pulse transformer are respectively coupled to the control ends of the third switch tube and the fourth switch tube of one of the second-layer balancing units corresponding to the second-layer driving unit, and the two secondary windings of the fourth pulse transformer are respectively coupled to the control ends of the third switch tube and the fourth switch tube of another second-layer balancing unit corresponding to the second-layer driving unit.

[0022] In order to achieve the above objectives, the utility model also provides an energy storage system, which includes at least two battery cells connected in series and a double-layer active balancing circuit as described in any one of the above items; wherein each of the battery cells includes two single cells connected in series.

[0023] In order to achieve the above object, the utility model also provides a battery management system, which includes the double-layer active balancing circuit described in any one of the above items.

[0024] Optionally, the battery management system is used to manage N battery cells connected in series, each of which includes two single cells connected in series; the battery management system also includes an analog acquisition front end and a microcontroller; the analog acquisition front end is coupled to the battery cell, and the microcontroller is coupled to the double-layer active balancing circuit;

[0025] The analog acquisition front end is configured to collect voltage information of each of the single cells and each of the battery units;

[0026] The microcontroller is configured to generate a first drive control signal and / or a second drive control signal according to the voltage information;

[0027] The double-layer active balancing circuit is configured to achieve voltage balancing of the single cells inside each of the battery cells according to the first drive control signal, and to achieve voltage balancing between the battery cells according to the second drive control signal.

[0028] In summary, compared with the prior art, the double-layer active balancing circuit, energy storage system and battery management system provided by the utility model have the following advantages:

[0029] The double-layer active balancing circuit provided by the utility model includes both a first-layer balancing module, the first-layer balancing module includes a first-layer balancing unit corresponding to the battery cells one by one (for example, an inductor can be used to realize the power transfer between the single cells in the same battery cell), and a second-layer balancing module (for example, a capacitor can be used to realize the power transfer between any two battery cells) and a selection drive module. The selection drive module can not only drive the first-layer balancing module to perform voltage balancing on the single cells of all the battery cells according to the received first drive control signal, but also drive the second-layer balancing module to perform voltage balancing on the power transfer between the two battery cells selected by the second drive control signal according to the received second drive control signal. With such a configuration, the utility model can realize the hierarchical balancing of the voltage between the single cells in the same battery cell and the voltage between different battery cells. It not only has the advantages of switching capacitor and inductor balancing at the same time, thereby significantly improving the efficiency and balancing speed of active balancing, but also has a simple circuit structure, clear logic, easy control, and convenient implementation.

[0030] Since the energy storage system and battery management system provided by the utility model belong to the same utility model concept as the double-layer active balancing circuit provided by the utility model, the energy storage system and battery management system provided by the utility model at least have all the advantages of the double-layer active balancing circuit provided by the utility model. For the beneficial effects of the energy storage system and battery management system provided by the utility model, please refer to the description of the beneficial effects of the double-layer active balancing circuit provided by the utility model in the above text, which will not be repeated here.

[0031] Since the energy storage system and battery management system provided by the utility model belong to the same utility model concept as the double-layer active balancing circuit provided by the utility model, the energy storage system and battery management system provided by the utility model at least have all the advantages of the double-layer active balancing circuit provided by the utility model. For the beneficial effects of the energy storage system and battery management system provided by the utility model, please refer to the description of the beneficial effects of the double-layer active balancing circuit provided by the utility model in the above text, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The structure frame of a battery management system using the double-layer active balancing circuit provided in the first embodiment of the utility model is Figure 2

[0033] Figure 2 Schematic diagram of the circuit structure of the first layer balancing module and the second layer balancing module of the double-layer active balancing circuit provided in the first embodiment of the utility model Figure 2

[0034] Figure 3a The schematic diagram of the discharge period of a single cell in the process of voltage equalization between single cells using the double-layer active equalization circuit provided by the utility model Figure 2

[0035] Figure 3b The schematic diagram of the double-layer active equalization circuit provided by the utility model during the voltage equalization process between the battery cells is shown in FIG. Figure 2

[0036] Figure 4 Schematic diagram of the circuit structure of the first layer driving unit of the selection driving module of the double-layer active equalization circuit provided in the first embodiment of the utility model Figure 2

[0037] Figure 5 Schematic diagram of the waveform of the first driving signal of the first driving circuit of the double-layer active equalization circuit provided in the first embodiment of the utility model Figure 2

[0038] Figure 6aThe schematic diagram of the battery cell discharge period during the voltage equalization process between battery cells using the double-layer active equalization circuit provided by the utility model Figure 2

[0039] Figure 6b The schematic diagram of the battery cell charging period during the voltage equalization process between battery cells using the double-layer active equalization circuit provided by the utility model Figure 2

[0040] Figure 7 This is a schematic diagram of the circuit structure of the second-layer driving unit of the selection driving module of the double-layer active balancing circuit provided in the first embodiment of the utility model. DETAILED DESCRIPTION

[0041] The following will be combined with schematic diagrams to describe in more detail the specific implementation of the double-layer active balancing circuit, energy storage system and battery management system provided by the utility model. According to the following description, the advantages and features of the utility model will be clearer. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiment of the utility model.

[0042] It should be understood that when an element is referred to as being "connected to" or "coupled to" another element, it may be directly connected to the other element or intervening elements may exist. In contrast, when an element is referred to as being "directly connected to" another element, there are no intervening elements.

[0043] The core idea of ​​the utility model is to provide a double-layer active balancing circuit, energy storage system and battery management system. The utility model not only has the advantages of switched capacitor and inductor balancing, can significantly improve the efficiency and balancing speed of active balancing, but also is easy to control and implement.

[0044] Embodiment 1

[0045] This embodiment provides a double-layer active balancing circuit for a battery management system. For example, see Figure 1 and Figure 2 ,in, Figure 1 The structure frame of a battery management system using the double-layer active balancing circuit provided by the embodiment of the utility model is Figure 2 Figure 2 A schematic diagram of the circuit structure of the first layer balancing module and the second layer balancing module of the double-layer active balancing circuit provided in the first embodiment of the utility model. Figure 1 and Figure 2 It can be seen that the battery management system is used to manage N battery cells connected in series. 1 , Bat 2 , ..., and Bat NEach of the battery cells comprises two battery cells connected in series. 1 Comprising two single cells B connected in series 11 and B 12 , the battery cell Bat 2 Comprising two single cells B connected in series 21 and B 22 ,......,Battery cell Bat N Comprising two single cells B connected in series N1 and B N2 .from Figure 1 and Figure 2 It can be seen that the dual-layer active balancing circuit 100 includes: a first-layer balancing module 110, a second-layer balancing module 120 and a selection driving module 130, wherein N≥2, the first-layer balancing module 110 includes the battery cell Bat 1 , Bat 2 ,......,Ba N The N first-layer balancing units 111, 112, ..., 11N correspond to each other. Since the first-layer balancing units 111, 112, ..., 11N correspond to the battery units Bat 1 , Bat 2 ,......,Ba N In order to facilitate understanding and avoid redundant description, this article uses the battery cell Bat 1 The corresponding first-layer balancing unit 111 is used as an example to illustrate the other battery units Bat 2 ,......,Bat N For details of the corresponding first-layer balancing units 112, ..., 11N, see the battery unit Bat 1 The corresponding description of the first layer equalization unit 111 is adaptively understood.

[0046] For example, please see Figure 1 and Figure 2 ,from Figure 1 and Figure 2 It can be seen that the first end, the second end and the third end of the first layer balancing unit 111 are respectively coupled to the corresponding battery unit Bat 1 The first end, the second end and the battery cell Bat 1 The two monomer cells B 11 and B 12The control end of the first-layer balancing unit 111 is coupled to the selection driving module 130; the first end, the second end and N-1 third ends of the second-layer balancing module 120 are respectively coupled to the battery unit Bat at the head end. 1 The first end of the battery cell Ba at the tail end N The second end and the N battery cells Bat 1 , Bat 2 ,......,Ba N The control end of the second-layer balancing module 120 is coupled to the selection driving module 130. The selection driving module 130 is configured to drive the first-layer balancing module 110 to all the battery cells Bat according to the received first driving control signal. 1 , Bat 2 ,......,Ba N The single cell B 11 and B 12 , B 21 and B 22 ,......,B N1 and B N2 voltage balancing, and driving the second layer balancing module 120 to balance the two battery cells (such as the battery cell Bat) selected by the second driving control signal according to the received second driving control signal. i and Bat j ) for voltage balancing.

[0047] It can be seen that the double-layer active balancing circuit 100 provided by the present invention includes a first-layer balancing module 110, the first-layer balancing module 110 includes a battery cell Bat 1 , Bat 2 ,......,Ba N The first layer equalization units 111, 112, ..., 11N (for example, inductors L may be used) correspond to each other. 1 Realize single cell B 11 and B 12 The power transfer between the two is done by using an inductor L 2 Realize single cell B 21 and B 22 The power transfer between the two, ..., using inductor L N Realize single cell B N1 and B N2 The second layer balancing module 120 (for example, a capacitor C can be used to realize the transfer of power between any two battery cells Bat i and Bat jThe power transfer between the two, 1≤i, j≤N) and the selection drive module 130, the selection drive module 130 can not only drive the first layer balancing module 110 to all the battery cells Bat according to the received first driving control signal 1 , Bat 2 ,......,Ba N The single cell B 11 and B 12 , B 21 and B 22 ,......,B N1 and B N2 voltage balancing, and can also drive the second layer balancing module 120 to balance the two battery cells Bat selected by the second driving control signal according to the received second driving control signal i and Bat j (1≤i, j≤N) is used to transfer the electricity between the two cells to balance the voltage. With such configuration, the utility model can achieve the hierarchical balance of the voltage between the single cells in the same battery unit and the voltage between different battery units. It not only has the advantages of switching capacitor and inductor balance, thereby significantly improving the efficiency and speed of active balance, but also has a simple circuit structure, clear logic, easy control and convenient implementation.

[0048] It should be noted that the present invention provides the single cell B 11 and B 12 , B 21 and B 22 ,......,B N1 and B N2 The specific type is not too limited, the single cell B 11 and B 12 , B 21 and B 22 ,......,B N1 and B N2 It can be but not limited to lithium-ion battery, nickel-metal hydride battery, lead-acid battery and lithium polymer battery, etc. Further, the utility model does not impose too many restrictions on the specific number N of the battery cells, and the battery cells can be 2, 3 or more.

[0049] In some preferred embodiments, please continue to refer to Figure 1 and Figure 2 ,from Figure 2 It can be seen that the first layer balancing unit 111 includes a first switch tube S 11 , the second switch tube S 12 and the first energy storage unit ( Figure 2 Not marked, it is the inductor L 1 and RL1 The first switch tube S 11 The first end is coupled to the battery cell Bat corresponding thereto. 1 The negative electrode of the first switch tube S 11 The second end of the second switch tube S 12 The first end of the first energy storage unit is coupled to the first end of the first energy storage unit, the second end of the first energy storage unit is coupled to the first node, and the second switch tube S 12 The second end is coupled to the battery cell Bat 1 The positive electrode of the first switch tube S 11 The control end and the second switch tube S 12 The control terminals of the selection drive modules 130 are respectively coupled to the selection drive modules 130 (see the attached Figure 4 The selection driving module 130 is configured to drive the first switch tubes S of all the first layer balancing units 111, 112, ..., 11N according to the first driving control signal. 11 , S 21 ,......,S N1 and the second switch tube S 12 , S 22 ,......,S N2 Therefore, for any battery cell Bat m (1≤m≤N), in this battery cell Bat m Two single cells B m1 and B m2 The voltage difference between Bm1 and V Bm2 ) is greater than the first preset threshold value, by connecting to the battery cell Bat m The first switch tube S of the corresponding first-layer balancing unit 11m m1 and the second switch tube S m2 The alternating on and off of the single cell B with higher power can m1 The power is transferred to the relatively low-power single cell B through the first energy storage unit. m2 , so that the battery cell Bat m Internal single cell B m1 and B m2 Furthermore, the utility model can simultaneously control all the battery cells Bat 1 , Bat 2 ,......,Bat N At the same time, each battery cell is balanced, which can further improve the efficiency and speed of active balancing. 1 , Bat 2,......,Bat N They will not affect each other, thus ensuring the balancing efficiency and balancing speed while having good balancing stability.

[0050] It should be noted that, as can be understood by those skilled in the art, the battery management system is issued when it detects that the single cells in the battery unit need to be balanced. Exemplarily, the battery management system can issue a first drive control signal when it detects that the voltage difference between the single cells in any one or more battery cells is greater than a first preset threshold. Furthermore, for more detailed information on how to generate the first drive control signal to start active balancing, please refer to the relevant technical adaptability understanding known to those skilled in the art. Due to space limitations, it will not be expanded here.

[0051] Preferably, the first energy storage unit comprises an inductor L 1 . Therefore, using an inductor as the first energy storage unit can make the double-layer active balancing circuit have a smaller area, and a smaller area will also make the circuit power consumption lower. It should be understood that those skilled in the art should be able to understand that this is only an exemplary description of a preferred implementation, and is not a limitation of the present utility model. When implementing the present utility model, energy storage devices should be reasonably selected according to actual needs to realize the function of the first energy storage unit. For example, an inductor L can be used. 1 , L 2 ,......,L N And in addition to the inductor L 1 , L 2 ,......,L N Other energy storage devices other than the inductor L are used as the first energy storage unit. They are not listed here one by one. Further, the utility model further 1 , L 2 ,......,L N There are no excessive restrictions and the inductor L should be reasonably selected according to actual needs. 1 , L 2 ,......,L N It can be, but is not limited to, an air-core coil, a ferrite coil, a copper-core coil, an aluminum-core coil, and the like.

[0052] Please continue to see Figure 2 ,from Figure 2 It can be seen that the first energy storage unit also includes the inductor L 1 The series connected resistor R L1 Therefore, not only can the stability of the circuit be improved, but also a resistor with a larger resistance value R can be reasonably selected. L1 , R L2 , ... and R LN, and can further reduce circuit energy consumption, thereby further improving the efficiency of active balancing.

[0053] For example, see Figure 3a and Figure 3b ,in, Figure 3a The schematic diagram of the discharge period of a single cell in the process of voltage equalization between single cells using the double-layer active equalization circuit provided by the utility model Figure 2 Figure 3b The schematic diagram of the battery cell charging period is shown in the figure below: m For example, when the battery cell Bat m Two single cells B m1 and B m2 When the voltage difference between the two meets the preset equilibrium condition (for example, the voltage difference between the two is greater than the first preset threshold), assuming that the single cell B m1 The power is higher than B m2 , each battery cell Bat 1 , Bat 2 ,......,Ba N And the switching inductor circuits composed of the corresponding first-layer balancing units 111, 112, ..., 11N are balanced respectively at the same time, so as to achieve energy balance between the single cells inside the battery unit.

[0054] For example, Figure 3a As shown, the battery cell Bat m For example, in the switching period t0-t1, the first switch tube S m1 The second switch tube S m2 When shut down, single cell B m1 The electrical energy will flow through the inductor L m Store up, the inductor L m The voltage and current can be calculated by the following equations (1) and (2):

[0055] V L (tt 0 )=V Bm1 -r L i L (tt 0 ) (1)

[0056]

[0057] In formula (1) and formula (2), V L For the inductor L m Voltage, V Bm1 For single cell B m1The voltage, r L For the inductor L m The equivalent resistance, i L For the inductor L m of current.

[0058] like Figure 3b As shown, during the switching period t1-t2, the second switch tube S m2 The first switch tube S is turned on. m1 When turned off, the inductor L m The stored electrical energy will be transferred to the single cell B m2 , inductance L m The voltage and current can be calculated by the following equations (3) and (4):

[0059] V L (tt 1 )=V Bm2 +r L i L (tt 1 ) (3)

[0060]

[0061] In formula (3) and formula (4), V L , for the inductor L m Voltage, V Bm2 For single cell B m2 The voltage, r L For the inductor L m The equivalent resistance, i L For the inductor L m of current.

[0062] It can be seen that when the first switch tube S 11 , S 21 ,......,S N1 , the second switch tube S 12 , S 22 ,......,S N2 When the switching frequency is high, the above two states continue to work alternately, and the excess energy of the high-voltage single cell flows to the low-voltage single cell through the switching inductor loop, thereby completing the mutual balance between the two single cells in all battery units.

[0063] In some exemplary embodiments, please continue to refer to Figure 1 , Figure 4 and Figure 5 , Figure 4 Schematic diagram of the circuit structure of the first layer driving unit of the selection driving module of the double-layer active equalization circuit provided in the first embodiment of the utility model Figure 2 Figure 5 A schematic diagram of the waveform of the first driving signal of the first driving circuit of the double-layer active equalization circuit provided in the first embodiment of the utility model. Figure 4 and Figure 5 It can be seen that the first driving control signal includes a set of complementary switch control signals PWMa and PWMb, and the microcontroller MCU of the battery management system includes a first pin (not shown in the figure) and a second pin (not shown in the figure) for transmitting the switch control signals PWMa and PWMb; the selection driving module 130 includes at least one first layer driving unit 131. For ease of understanding and description, the following description takes the kth first layer driving unit 131 coupled to two adjacent first layer balancing units 11i and 11j as an example for explanation. For more detailed information about the first layer driving units coupled to other first layer balancing units, please refer to the description below for adaptive understanding.

[0064] from Figure 4 It can be seen that the first layer driving unit 131 includes a first driving circuit 1311 and a first pulse transformer T131 and a second pulse transformer T132 each having two secondary windings. Exemplarily, the first input end of the first driving circuit 1311 is coupled to the first pin, the second input end of the first driving circuit 1311 is coupled to the second pin, the two output ends of the first driving circuit 1311 are respectively coupled to the primary winding of the first pulse transformer T131 and the primary winding of the second pulse transformer T132, and the first driving circuit 1311 is configured to generate a pair of complementary first driving signals according to the switch tube control signal. The two secondary windings of the first pulse transformer T131 are respectively coupled to the first switch tubes S of any two of the first layer balancing units 11i and 11j corresponding to the first driving circuit 1311. i 1 and S j 1 control terminal to transmit one of the first driving signals ( Figure 4 The two secondary windings of the second pulse transformer T132 are respectively coupled to the second switch tubes S of the first layer balancing units 11i and 11j. i2 and S j2 to transmit another of the first driving signals ( Figure 4 The example corresponds to the switch tube control signal PWMa).

[0065] Depend on Figure 4 and Figure 5It can be concluded that the double-layer active balancing circuit 100 provided by the utility model, the microcontroller MCU outputs a set of complementary switch tube control signals PWMa and PWMb, which are then passed through the first drive circuit 1311 to generate a pair of complementary first drive signals with dead zones, and then the first pulse transformer T131 and the second pulse transformer T132 are used to expand one control signal into two control signals, which can drive all battery cells Bat at the same time. 1 , Bat 2 , ..., and Bat N The first switch tube S 11 , S 21 ,......,S N1 Shutdown (such as Figure 5 The switching cycle shown in 0~t0, t1~t2, ...) / conduction (such as Figure 5 The switching cycle 0~t1, t2~t3, ......) shown in the figure and the second switching tube S 12 , S 22 ,......,S N2 Conductivity (such as Figure 5 The switching cycle shown in 0~t0, t1~t2, ..... ) / turn off (such as Figure 5 The switching cycles 0~t1, t2~t3, ...) shown in the figure can significantly save the pin resources of the microcontroller MCU and simplify the control complexity. Furthermore, for multiple first-layer balancing units 111, 112, ..., 11N that require multiple identical control signals, only one control signal needs to be added to eliminate the bootstrap circuit, which can further reduce the area of ​​the double-layer active balancing circuit 100, thereby further reducing the power consumption of the double-layer active balancing circuit 100, and thus improving the balancing efficiency. Furthermore, the first pulse transformer T131 and the second pulse transformer T132 each have two secondary windings, which can not only expand a pair of complementary first drive signals into two control signals, but also enhance the driving capability, thereby further improving the balancing efficiency and balancing speed.

[0066] Preferably, please continue to see Figure 2 , Figure 6a and Figure 6b ,in, Figure 6a The schematic diagram of the battery cell discharge period during the voltage equalization process between battery cells using the double-layer active equalization circuit provided by the utility model Figure 2 Figure 6b The figure is a schematic diagram of the battery cell charging period during the voltage equalization process between battery cells using the double-layer active equalization circuit provided by the utility model. Figure 2 It can be seen that the second-layer balancing module 120 includes the battery unit Bat 1 , Bat2 ,......,Bat N One-to-one corresponding second-layer balancing units 121, 122, ..., 12N and a second energy storage unit (exemplarily, such as Figure 2 The first and second ends of the second-layer balancing units 121, 122, ..., 12N are respectively coupled to the battery cells Bat corresponding thereto. 1 , Bat 2 ,......,Bat N The third end and the fourth end of all the second-layer balancing units 121, 122, ..., 12N are respectively coupled to the first end and the second end of the second energy storage unit. Further, the selection drive module 130 is configured to drive the two battery cells (such as Figure 6a and Figure 6b The battery cell shown in Bat i and Bat j ) The corresponding second-layer balancing units 12i and 12j are alternately turned on and off, and in the process of alternating on and off, other second-layer balancing units 12k (1≤k≤N, and k≠i, k≠j) are continuously controlled to remain in the off state.

[0067] It can be seen that the double-layer active balancing circuit 100 provided by the present invention, the second-layer balancing module 120 includes second-layer balancing units 121, 122, ..., 12N and a second energy storage unit, and the second-layer balancing units 121, 122, ..., 12N and the battery unit Bat 1 , Bat 2 ,......,Bat N One-to-one correspondence, thus, any two battery cells (such as battery cell Bat i and Bat j ), the circuit structure is simple and easy to control. Further, the selection drive module 130 can drive the two battery cells (such as battery cells Bat 2 and 3 ) selected by the second drive control signal according to the second drive control signal. i and Bat j ) corresponding to the second-layer balancing units (such as the second-layer balancing units 12i and 12j) are alternately turned on and off, and the other second-layer balancing units are continuously controlled to remain in the off state during the alternating on and off process. Therefore, when actively balancing any two battery cells, the active balancing current only flows between the battery cells to be balanced, and does not flow through the battery cells (such as the battery cell Bat iand Bat j ) between other battery cells, not only can it reduce the problem of cell heating caused by the internal resistance of the single cell, but it can also reduce losses and further improve the balancing efficiency.

[0068] Since the second-layer balancing units 121, 122, ..., 12N and the battery unit Bat 1 , Bat 2 ,......,Bat N In order to facilitate understanding and avoid redundant description, this article uses the battery cell Bat 1 The corresponding second-layer balancing unit 121 is used as an example to illustrate the other battery units Bat 2 ,......,Bat N For details of the corresponding second-layer balancing units 122, ..., 12N, see the battery unit Bat 1 The corresponding description of the first layer equalization unit 121 is adaptively understood.

[0069] Preferably, in some of the exemplary embodiments, please continue to refer to Figure 2 ,from Figure 2 It can be seen that the second layer balancing unit 121 includes a third switch tube S 13 and the fourth switch tube S 14 , the third switch tube S 13 The first end is coupled to the battery cell Bat corresponding thereto. 1 The negative electrode of the fourth switch tube S 14 The first end is coupled to the battery cell Bat 1 The positive electrode of the third switch tube S 13 The second end of Figure 2 The first end of the capacitor C) in the fourth switch tube S 14 The second end of the third switch tube S is coupled to the second end of the second energy storage unit. 13 The control end and the fourth switch tube S 14 The control ends are respectively coupled to the selection drive module 130 (please refer to Figure 1 See also Figure 7 ). Thus, when the switching frequency of the third switch and the fourth switch is high, the two battery cells to be balanced and the respective third switch and fourth switch are 4 The charge and discharge states of the formed switching capacitor circuit continuously work alternately, so that the excess energy of the high-voltage battery cell flows to the low-voltage battery cell through the switching capacitor circuit, and the mutual balance between any battery cells can be achieved.

[0070] For example, the battery cell Batj With battery cell Bat i When the voltage difference between the two exceeds the second preset threshold, for example, if the battery cell Bat j The voltage of the battery cell Bat i The voltage of Figure 6a As shown, first, turn on the battery cell Bat j The corresponding third switch tube S in the second layer equalization unit 12j 3j and the fourth switch tube S 4j The charge is discharged to the capacitor C, and then the third switch tube S is turned off. 3j and the fourth switch tube S 4j Next, turn on the battery cell Bat i The third switch tube S in the corresponding second-layer balancing unit 12i 3i and the fourth switch tube S 4i , transfers charge from capacitor C to battery cell Bat i , and repeat this process until the battery cell Bat j and battery cell Bat i It should be understood that, during the process of the second-layer balancing unit 12j and the second-layer balancing unit 12i being alternately turned on and off, all other second-layer balancing units except the second-layer balancing units 12j and 12i are in the off state.

[0071] Preferably, in some exemplary embodiments, the second energy storage unit includes a capacitor C. Thus, the battery unit Bat can be further improved. 1 , Bat 2 ,......,Bat N The balancing speed between them. It should be understood that those skilled in the art should be able to understand that this is only an exemplary description of a preferred embodiment and is not a limitation of the present invention. When implementing the present invention, the energy storage device should be reasonably selected according to actual needs to realize the function of the second energy storage unit. For example, capacitor C and other energy storage devices other than capacitor C can be used as the second energy storage unit. They are not listed here. Furthermore, the present invention does not impose too many restrictions on the capacitor C, which should be reasonably selected according to actual needs. Exemplarily, the capacitor C can be, but is not limited to, a ceramic capacitor, a mica capacitor, and a polypropylene capacitor. Furthermore, the second energy storage unit may also include a resistor (not shown in the figure) connected in series with the inductor C. In order to improve the stability of the circuit and further reduce energy consumption by selecting the resistance value of the resistor, the efficiency of active balancing can be further improved.

[0072] Please combine Figure 1 and Figure 2See also Figure 7 , Figure 7 This is a schematic diagram of the circuit structure of the second layer driving unit of the selection driving module of the double-layer active equalization circuit provided in the first embodiment of the utility model. Figure 1 , Figure 2 and Figure 7 It can be seen that the microcontroller MCU of the battery management system includes a third pin (not shown in the figure) for transmitting the second drive control signal and at least three address pins A1, A2 and A3; the selection drive module 130 also includes a multiplexing circuit MUX (such as a multiplexer) and at least one second layer driving unit 132, the signal input end of the multiplexing circuit MUX is coupled to the third pin, and the three channel selection pins of the multiplexing circuit MUX are respectively coupled to the three address pins A1, A2 and A3 in a one-to-one correspondence; each two output ends of the multiplexing circuit MUX are respectively coupled to two input ends of a second layer driving unit 132, and the output end of the second layer driving unit 132 is respectively coupled to the control end of any two corresponding second layer balancing units (such as the second layer balancing units 12i and 12j). The multiplexing circuit MUX is configured to drive one of the second layer balancing units (such as the second layer balancing unit 12i) selected by the second drive control signal to turn on according to the second drive control signal, and the other second layer balancing units are all turned off.

[0073] Since only one pair of switch tubes is turned on at the same time when the switch capacitor circuit is enabled, and the other switch tubes are turned off, the multiplexing circuit MUX can be used to control the control signals of multiple switch tubes with the least microcontroller MCU resources. Figure 7 As shown, the multiplexing circuit MUX realizes 3 control signals, which can realize the multiplexing of 8 channels. In combination with multiple second-layer driving units 132, the microcontroller MCU can output a control signal PWMc to control 8 pairs of switch tubes. Since the structures of the second-layer balancing units connected to the multiplexing circuit MUX are the same, in order to facilitate understanding and avoid redundant description, the battery cell Bat is used as the corresponding balancing unit. i and Bat j The second-layer balancing unit 132 is used as an example for explanation. For details of other second-layer balancing units, please refer to the corresponding battery unit Bat i and Bat j The related description of the second layer equalization unit 132 is adaptively understood.

[0074] Preferably, in some of the exemplary embodiments, please continue to refer to Figure 7 ,from Figure 7It can be seen that the second-layer driving unit 132 includes a second driving circuit 1321 and a third pulse transformer T133 and a fourth pulse transformer T134, each having two secondary windings; the two input ends of the second driving circuit 1321 are respectively coupled to two output ends of the multiplexing circuit MUX, one of the output ends of the second driving circuit 1321 is coupled to the primary winding of the third pulse transformer T133, and the other output end of the second driving circuit 1321 is coupled to the primary winding of the fourth pulse transformer T134; the two secondary windings of the third pulse transformer T133 are respectively coupled to the third switch tube S of one of the second-layer balancing units 12i corresponding to the second-layer driving unit 131. i3 and the fourth switch tube S i4 The two secondary windings of the fourth pulse transformer T134 are respectively coupled to the third switch tube S of another second-layer balancing unit 12j corresponding to the second-layer driving unit 131. j3 and the fourth switch tube S j4 Thus, the driving capability can be enhanced by the second driving circuit 1321 and the third pulse transformer T133 and the fourth pulse transformer T134 each having two secondary windings, thereby further improving the battery cell Bat 1 , Bat 2 ,......,Bat N The balance efficiency and balance speed between them.

[0075] In summary, the double-layer active balancing circuit provided by the utility model not only has the advantages of switched capacitor and inductor balancing, but also can significantly improve the efficiency and balancing speed of active balancing, and the circuit structure is simple and the logic is clear, and only basic inductors, capacitors and switching devices are needed to realize the battery cell Bat 1 , Bat 2 ,......,Bat N Internal single cell B 11 and B 12 , B 21 and B 22 ,......,B N1 and B N2 and battery cell Bat 1 , Bat 2 ,......,Bat N The balance between them is easy to control and implement.

[0076] It can be understood that the present invention provides the first switch tube S 11 , S 21 ,......,S N1 , the second switch tube S12 , S 22 ,......,S N2 , the third switch tube S 13 , S 23 ,......,S N3 And the fourth switch tube S 14 , S 24 ,......,S N4 Without further limitation, for example, these switch tubes may be PMOS tubes or NMOS tubes.

[0077] Embodiment 2

[0078] This embodiment provides an energy storage system, the energy storage system includes at least two battery cells connected in series and the double-layer active balancing circuit 100 described in any implementation of the above embodiment 1; wherein each of the battery cells includes two single cells connected in series. Since the energy storage system provided by the utility model and the double-layer active balancing circuit provided by the utility model belong to the same utility model concept, the energy storage system provided by the utility model at least has all the advantages of the double-layer active balancing circuit provided by the utility model. For the beneficial effects of the energy storage system provided by the utility model, please refer to the description of the beneficial effects of the double-layer active balancing circuit provided by the utility model above, which will not be repeated here.

[0079] Embodiment 3

[0080] This embodiment provides a battery management system. For example, please continue to refer to Figure 1 ,from Figure 1 It can be seen that the battery management system includes the double-layer active balancing circuit 100 provided by the utility model. Since the battery management system provided by the utility model and the double-layer active balancing circuit 100 provided by the utility model belong to the same utility model concept, the battery management system provided by the utility model at least has all the advantages of the double-layer active balancing circuit 100 provided by the utility model. For the beneficial effects of the battery management system provided by the utility model, please refer to the detailed description of the beneficial effects of the double-layer active balancing circuit 100 provided by the utility model above, which will not be expanded here. For example, the battery management system is used to manage N battery cells Bat connected in series 1 , Bat 2 ,......,Bat N Each of the battery cells Bat 1 , Bat 2 ,......,Bat N Comprising two single cells B connected in series 11 and B 12 , B 21and B 22 ,......,B N1 and B N2 .

[0081] In some exemplary embodiments, please continue to refer to Figure 1 ,from Figure 1 It can be seen that the battery management system also includes an analog acquisition front end AFC and a microcontroller MCU; the analog acquisition front end AFC is coupled to the battery unit Bat 1 , Bat 2 ,......,Bat N The microcontroller MCU is coupled to the double-layer active balancing circuit 100. Further, the analog acquisition front end AFC is configured to collect the single cell B of each section. 11 and B 12 , B 21 and B 22 ,......,B N1 and B N2 And each of the battery cells Bat 1 , Bat 2 ,......,Bat N voltage information; the microcontroller MCU is configured to generate a first drive control signal and / or a second drive control signal according to the voltage information; the double-layer active balancing circuit 100 is configured to implement each of the battery cells Bat according to the first drive control signal 1 , Bat 2 ,......,Bat N The internal single cell Bat 1 , Bat 2 ,......,Bat N voltage balance, and realize each of the battery cells Bat according to the second drive control signal 1 , Bat 2 ,......,Bat N Voltage balance between.

[0082] It can be seen that the battery management system provided by the utility model can achieve hierarchical balancing of the voltages between individual cells in a battery unit and between different battery units, and can significantly improve the efficiency and speed of active balancing.

[0083] In particular, how the analog acquisition front end AFC acquires the single cell B in each section 11 and B 12 , B 21 and B 22 ,......,B N1and B N2 And each of the battery cells Bat 1 , Bat 2 ,......,Bat N For more detailed information on the voltage information, please refer to the related technologies known to those skilled in the art. Due to space limitations, this article will not elaborate on this. Furthermore, the utility model does not impose too many restrictions on the communication method between the analog acquisition front end AFC and the microcontroller MCU. Preferably, the analog acquisition front end AFC and the microcontroller MCU use an I2C communication method.

[0084] Next, the battery management system provided by this embodiment is used to manage N battery cells Bat connected in series. 1 , Bat 2 ,......,Bat N The control process of active balancing of the energy storage system is briefly described as follows:

[0085] First, the analog acquisition front-end AFC collects 1 to 2N single cells B 11 , B 12 , B 21 , B 22 ,......,B N1 , B N2 The voltage of each two adjacent single cells B 11 and B 12 , B 21 and B 22 ,......,B N1 and B N2 Form a battery cell Bat 1 , Bat 2 ,......,Bat N , there are N battery cells, and calculate the same battery cell Bat 1 , Bat 2 ,......,Bat N Two internal single cells B 11 and B 12 , B 21 and B 22 ,......,B N1 and B N2 If there is any battery cell (such as battery cell Bat i ) in a single cell (such as B i1 and B i2 ) is greater than the first preset threshold, then the driving module 130 is selected to start all the first-layer balancing units 111, 112, ..., 11N to perform single cell B 11 and B12 , B 21 and B 22 ,......,B N1 and B N2 The switch inductor layer is actively balanced until all battery cells Bat 1 , Bat 2 ,......,Bat N Single cell B 11 and B 12 , B 21 and B 22 ,......,B N1 and B N2 If the voltage difference is less than the first preset threshold, the active balancing of the inductor layer is turned off. 11 and B 12 , B 21 and B 22 ,......,B N1 and B N Internal single cell B 11 and B 12 , B 21 and B 22 ,......,B N1 and B N2 balance.

[0086] Then, when all the battery cells Bat 1 , Bat 2 ,......,Ba N Single cell B 11 and B 12 , B 21 and B 22 ,......,B N1 and B N When the voltage difference of all the battery cells Bat is less than the first preset threshold, the following steps are iteratively performed until all the battery cells Bat 1 , Bat 2 ,......,Bat N The voltage difference between the two is less than the second preset threshold: Get the voltage of each battery cell Bat 1 , Bat 2 ,......,Ba N The overall voltage value of the battery cell with the largest voltage and the battery cell with the smallest voltage is determined to determine whether the voltage difference between the battery cell with the largest voltage and the battery cell with the smallest voltage is greater than a second preset threshold value. If so, the second layer balancing module 120 is started by selecting the driving module 130 to balance the two battery cells (for example, the battery cell Bat i and Bat j) to balance the voltage until all battery cells Bat 1 , Bat 2 ,......,Ba N When the voltage difference between the two is less than the second preset threshold, the active balancing of the switch capacitor circuit is turned off. For example, the battery cells Bat can be sorted according to the voltage value by bubble sorting. 1 , Bat 2 ,......,Ba N Finally, enter the next balancing cycle as described above.

[0087] In summary, compared with the prior art, the double-layer active balancing circuit, energy storage system and battery management system provided by the utility model have the following advantages:

[0088] The double-layer active balancing circuit provided by the utility model includes both a first-layer balancing module, the first-layer balancing module includes a first-layer balancing unit corresponding to the battery cells one by one (for example, an inductor can be used to realize the power transfer between the single cells in the same battery cell), and a second-layer balancing module (for example, a capacitor can be used to realize the power transfer between any two battery cells) and a selection drive module. The selection drive module can not only drive the first-layer balancing module to perform voltage balancing on the single cells of all the battery cells according to the received first drive control signal, but also drive the second-layer balancing module to perform voltage balancing on the power transfer between the two battery cells selected by the second drive control signal according to the received second drive control signal. With such a configuration, the utility model can realize the hierarchical balancing of the voltage between the single cells in the same battery cell and the voltage between different battery cells. It not only has the advantages of switching capacitor and inductor balancing at the same time, thereby significantly improving the efficiency and balancing speed of active balancing, but also has a simple circuit structure, clear logic, easy control, and convenient implementation.

[0089] Since the energy storage system and battery management system provided by the utility model belong to the same utility model concept as the double-layer active balancing circuit provided by the utility model, the energy storage system and battery management system provided by the utility model at least have all the advantages of the double-layer active balancing circuit provided by the utility model. For the beneficial effects of the energy storage system and battery management system provided by the utility model, please refer to the description of the beneficial effects of the double-layer active balancing circuit provided by the utility model in the above text, which will not be repeated here.

[0090] It should also be noted that, although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the above disclosed technical content can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

[0091] It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are merely used to distinguish between the various components, elements, steps, etc. in the specification, and are not used to indicate the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0092] It should also be recognized that the terms described herein are only used to describe specific embodiments and are not used to limit the scope of the utility model. It must be noted that the singular forms "one" and "a kind" used herein and in the appended claims include plural references unless the context clearly indicates the opposite meaning. For example, a reference to "a step" or "a device" means a reference to one or more steps or devices, and may include secondary steps and secondary devices. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have a logical "or" definition, rather than a logical "exclusive or" definition, unless the context clearly indicates the opposite meaning. In addition, the implementation of the method and / or device in the embodiment of the utility model may include performing the selected task manually, automatically, or in combination.

Claims

1. A double-layer active equalization circuit, characterized in that: Used in a battery management system, the battery management system is used to manage N battery cells connected in series, each of the battery cells includes two single cells connected in series, the double-layer active balancing circuit includes: a first-layer balancing module, a second-layer balancing module and a selection drive module, wherein N≥2, the first-layer balancing module includes N first-layer balancing units corresponding to the battery cells one by one; The first end, the second end and the third end of the first-layer balancing unit are respectively coupled to the first end, the second end and the first nodes of the two single cells of the battery unit corresponding thereto, and the control end of the first-layer balancing unit is coupled to the selection driving module; the first end, the second end and N-1 third ends of the second-layer balancing module are respectively coupled to the first end of the battery unit at the head end, the second end of the battery unit at the tail end and N-1 second nodes of the N battery units; the control end of the second-layer balancing module is coupled to the selection driving module; The selection drive module is configured to drive the first layer balancing module to perform voltage balancing on the single cells of all the battery cells according to the received first drive control signal, and to drive the second layer balancing module to perform voltage balancing on the two battery cells selected by the second drive control signal according to the received second drive control signal.

2. The double-layer active equalization circuit according to claim 1, characterized in that: The first-layer balancing unit includes a first switch tube, a second switch tube and a first energy storage unit; the first end of the first switch tube is coupled to the negative electrode of the battery unit corresponding thereto, the second end of the first switch tube and the first end of the second switch tube are coupled to the first end of the first energy storage unit, the second end of the first energy storage unit is coupled to the first node, the second end of the second switch tube is coupled to the positive electrode of the battery unit, and the control end of the first switch tube and the control end of the second switch tube are respectively coupled to the selection drive module; The selection driving module is configured to drive the first switch tubes and the second switch tubes of all the first-layer balancing units to be alternately turned on and off according to the first driving control signal.

3. The double-layer active equalization circuit according to claim 2, characterized in that: The first energy storage unit includes an inductor.

4. The double-layer active equalization circuit according to claim 2, characterized in that: The first drive control signal includes a set of complementary switch tube control signals, and the microcontroller of the battery management system includes a first pin and a second pin for transmitting the switch tube control signal; the selection drive module includes at least one first layer drive unit, and the first layer drive unit includes a first drive circuit and a first pulse transformer and a second pulse transformer each having two secondary windings; The first input terminal of the first driving circuit is coupled to the first pin, the second input terminal of the first driving circuit is coupled to the second pin, the two output terminals of the first driving circuit are respectively coupled to the primary winding of the first pulse transformer and the primary winding of the second pulse transformer, and the first driving circuit is configured to generate a pair of complementary first driving signals according to the switch tube control signal; The two secondary windings of the first pulse transformer are respectively coupled to the control ends of the first switching tubes of any two first-layer balancing units corresponding to the first drive circuit to transmit one of the first drive signals; the two secondary windings of the second pulse transformer are respectively coupled to the control ends of the second switching tubes of the two first-layer balancing units to transmit the other first drive signal.

5. The double-layer active equalization circuit according to claim 1, characterized in that: The second-layer balancing module includes a second-layer balancing unit corresponding to the battery cells one by one and a second energy storage unit, the first end and the second end of the second-layer balancing unit are respectively coupled to the negative electrode and the positive electrode of the corresponding battery cell, the third end and the fourth end of all the second-layer balancing units are respectively coupled to the first end and the second end of the second energy storage unit, and the control ends of all the second-layer balancing units are respectively coupled to the selection drive module; The selection driving module is configured to drive the second-layer balancing units corresponding to the two battery cells selected by the second driving control signal to be alternately turned on and off according to the second driving control signal, and continuously control the other second-layer balancing units to remain in an off state during the alternating turning on and off process.

6. The double-layer active equalization circuit according to claim 5, characterized in that: The second-layer balancing unit includes a third switch tube and a fourth switch tube, wherein the first end of the third switch tube is coupled to the negative electrode of the corresponding battery cell, the first end of the fourth switch tube is coupled to the positive electrode of the battery cell, the second end of the third switch tube is coupled to the first end of the second energy storage unit, the second end of the fourth switch tube is coupled to the second end of the second energy storage unit, and the control end of the third switch tube and the control end of the fourth switch tube are respectively coupled to the selection drive module.

7. The double-layer active equalization circuit according to claim 5, characterized in that: The second energy storage unit includes a capacitor.

8. The double-layer active equalization circuit according to claim 5, characterized in that: The microcontroller of the battery management system includes a third pin for transmitting the second drive control signal and at least three address pins; the selection drive module also includes a multiplexing circuit and at least one second-layer drive unit, the signal input end of the multiplexing circuit is coupled to the third pin, and the three channel selection pins of the multiplexing circuit are respectively coupled to the three address pins in a one-to-one correspondence; every two output ends of the multiplexing circuit are respectively coupled to two input ends of one of the second-layer drive units, and the output ends of the second-layer drive units are respectively coupled to the control ends of any two corresponding second-layer balancing units; The multiplexing circuit is configured to drive one of the second-layer balancing units selected by the second driving control signal to turn on according to the second driving control signal, and to turn off the other second-layer balancing units.

9. The double-layer active equalization circuit according to claim 8, characterized in that: The second-layer driving unit includes a second driving circuit and a third pulse transformer and a fourth pulse transformer each having two secondary windings; the two input ends of the second driving circuit are respectively coupled to two output ends of the multiplexing circuit, one output end of the second driving circuit is coupled to the primary winding of the third pulse transformer, and the other output end of the second driving circuit is coupled to the primary winding of the fourth pulse transformer; the two secondary windings of the third pulse transformer are respectively coupled to the control ends of the third switch tube and the fourth switch tube of one of the second-layer balancing units corresponding to the second-layer driving unit, and the two secondary windings of the fourth pulse transformer are respectively coupled to the control ends of the third switch tube and the fourth switch tube of another second-layer balancing unit corresponding to the second-layer driving unit.

10. An energy storage system, characterized in that: It comprises at least two battery cells connected in series and a double-layer active balancing circuit as claimed in any one of claims 1 to 9; wherein each of the battery cells comprises two single cells connected in series.

11. A battery management system, characterized in that: The battery management system comprises a double-layer active balancing circuit as claimed in any one of claims 1 to 9.

12. The battery management system according to claim 11, characterized in that: The battery management system is used to manage N battery cells connected in series, each of which includes two single cells connected in series; the battery management system also includes an analog acquisition front end and a microcontroller; the analog acquisition front end is coupled to the battery cell, and the microcontroller is coupled to the double-layer active balancing circuit; The analog acquisition front end is configured to collect voltage information of each of the single cells and each of the battery units; The microcontroller is configured to generate a first drive control signal and / or a second drive control signal according to the voltage information; The double-layer active balancing circuit is configured to achieve voltage balancing of the single cells inside each of the battery cells according to the first drive control signal, and to achieve voltage balancing between the battery cells according to the second drive control signal.

Images