Battery equalization circuit and battery system

Abstract

The utility model discloses a battery equalization circuit and a battery system, the battery equalization circuit is suitable for carrying out voltage equalization on a plurality of battery monomers connected in series, the plurality of battery monomers form a first battery pack and a second battery pack, the battery equalization circuit comprises a bidirectional equalization unit, a first controllable switch unit and a second controllable switch unit, the first controllable switch unit provides first electric energy released by the first battery pack for the bidirectional equalization unit, the second controllable switch unit provides second electric energy released by the second battery pack for the bidirectional equalization unit, and the bidirectional equalization unit is configured to perform isolation conversion on the first electric energy. And performing equalization charging on the second battery pack according to the first electric energy after isolation conversion, performing equalization charging on the first battery pack according to the first electric energy, performing isolation conversion on the second electric energy, and performing equalization charging on the first battery pack according to the second electric energy after isolation conversion. And performing equalizing charging on the second battery pack according to the second electric energy.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly relates to a battery equalization circuit and a battery system. Background Art

[0002] The battery monomer of a lithium-ion battery has a small capacity and a low load capacity. It is necessary to form a module by connecting battery monomers in a certain way to increase the voltage platform and stored energy of the battery system. However, the production process and production environment of the batteries are inconsistent, resulting in differences in battery performance consistency, and this consistency difference will gradually accelerate during use. Therefore, equalization technology is usually used to optimize battery consistency. Since passive equalization will cause energy waste, and untimely heat dissipation will lead to safety risks in the battery pack, active equalization is usually adopted in related technologies.

[0003] In related technologies, the active equalization method is usually isolated single-ended flyback DC-DC (direct current-direct current) equalization. This method is applicable to a 1-to-1 battery group or battery pack. Therefore, it is impossible to achieve equalization between any battery groups or battery packs. Utility Model Content

[0004] The present utility model aims to solve at least one of the technical problems in related technologies to some extent. For this purpose, the first object of the present utility model is to propose a battery equalization circuit, which realizes bidirectional energy transfer of the battery group through a bidirectional equalization unit, can meet the active equalization between any battery groups, and thus improves the efficiency of active equalization.

[0005] The second object of the present utility model is to propose a battery system.

[0006] To achieve the above object, according to an embodiment of the first aspect of the present utility model, a battery equalization circuit is proposed. The battery equalization circuit is suitable for performing voltage equalization on a plurality of series-connected battery monomers. The plurality of battery monomers form a first battery group and a second battery group. The battery equalization circuit includes: a bidirectional equalization unit, a first controllable switch unit, and a second controllable switch unit. Among them, one end of the first controllable switch unit is suitable for connecting to the first battery group to provide the first electric energy released by the first battery group to the bidirectional equalization unit. One end of the second controllable switch unit is suitable for connecting to the second battery group to provide the second electric energy released by the second battery group to the bidirectional equalization unit. The bidirectional equalization unit is configured to perform isolation transformation on the first electric energy, and perform equalization charging on the second battery group according to the isolated and transformed first electric energy, and perform equalization charging on the first battery group according to the first electric energy, and perform isolation transformation on the second electric energy, and perform equalization charging on the first battery group according to the isolated and transformed second electric energy, and perform equalization charging on the second battery group according to the second electric energy.

[0007] The battery equalization circuit according to an embodiment of the present utility model includes a bidirectional equalization unit, a first controllable switch unit, and a second controllable switch unit. Among them, one end of the first controllable switch unit is adapted to be connected to a first battery pack to supply the first electric energy released by the first battery pack to the bidirectional equalization unit. One end of the second controllable switch unit is adapted to be connected to a second battery pack to supply the second electric energy released by the second battery pack to the bidirectional equalization unit. The bidirectional equalization unit is configured to perform isolation transformation on the first electric energy, and perform equalization charging on the second battery pack according to the isolated and transformed first electric energy, and perform equalization charging on the first battery pack according to the first electric energy, and perform isolation transformation on the second electric energy, and perform equalization charging on the first battery pack according to the isolated and transformed second electric energy, and perform equalization charging on the second battery pack according to the second electric energy. Thus, the bidirectional equalization unit can perform equalization charging on the first battery pack and the second battery pack according to the excess electric energy of the first battery pack, or can perform equalization charging on the first battery pack and the second battery pack according to the excess electric energy of the second battery pack, realizing the bidirectional energy transfer of the battery packs, thereby meeting the active equalization between any battery packs, and further improving the efficiency of active equalization.

[0008] According to an embodiment of the present utility model, the bidirectional equalization unit includes: a transformer, which includes a first winding, a second winding, a third winding, and a fourth winding. One end of the first winding is connected to one end of the second winding and has a first node. The other end of the first winding and the other end of the second winding are respectively connected to the negative electrodes of each battery cell in the first battery pack through the first controllable switch unit. One end of the third winding is connected to one end of the fourth winding and has a second node. The other end of the third winding and the other end of the fourth winding are respectively connected to the negative electrodes of each battery cell in the second battery pack through the second controllable switch unit. Among them, the first node is connected to the positive electrode of each battery cell in the first battery pack through the first controllable switch unit, and the second node is connected to the positive electrode of each battery cell in the second battery pack through the second controllable switch unit.

[0009] According to an embodiment of the present utility model, the first controllable switch unit includes: at least one first controllable switch module. One end of each first controllable switch module is adapted to be connected to the negative electrode of a battery cell in the first battery pack, and the other end of each first controllable switch module is respectively connected to the other end of the first winding and the other end of the second winding; at least one second controllable switch module. One end of each second controllable switch module is adapted to be connected to the positive electrode of a battery cell in the first battery pack, and the other end of each second controllable switch module is connected to the first node.

[0010] According to an embodiment of the present utility model, the second controllable switch unit includes: at least one third controllable switch module, one end of each third controllable switch module is adapted to be connected to the negative electrode of a battery cell in the second battery pack, and the other end of each third controllable switch module is respectively connected to the other end of the third winding and the other end of the fourth winding; at least one fourth controllable switch module, one end of each fourth controllable switch module is adapted to be connected to the positive electrode of a battery cell in the second battery pack, and the other end of each fourth controllable switch module is connected to the second node.

[0011] According to an embodiment of the present utility model, the first controllable switch module, the second controllable switch module, the third controllable switch module and the fourth controllable switch module respectively include at least one switching device.

[0012] According to an embodiment of the present utility model, there are two switching devices, the two switching devices are respectively MOS transistors, and the two MOS transistors are designed in a back-to-back manner.

[0013] According to an embodiment of the present utility model, the first winding and the third winding are respectively low-voltage windings, and the second winding and the fourth winding are respectively high-voltage windings.

[0014] According to an embodiment of the present utility model, the bidirectional equalization unit further includes: a fifth controllable switch module, one end of the fifth controllable switch module is connected to the other end of the first winding, and the other end of the fifth controllable switch module is connected to the negative electrode of each battery cell in the first battery pack through the first controllable switch unit; a sixth controllable switch module, one end of the sixth controllable switch module is connected to the other end of the second winding, and the other end of the sixth controllable switch module is connected to the negative electrode of each battery cell in the first battery pack through the first controllable switch unit; a seventh controllable switch module, one end of the seventh controllable switch module is connected to the other end of the third winding, and the other end of the seventh controllable switch module is connected to the negative electrode of each battery cell in the second battery pack through the second controllable switch unit; an eighth controllable switch module, one end of the eighth controllable switch module is connected to the other end of the fourth winding, and the other end of the eighth controllable switch module is connected to the negative electrode of each battery cell in the second battery pack through the second controllable switch unit.

[0015] According to an embodiment of the present utility model, the battery equalization circuit further includes: a current detection unit, adapted to detect the equalization current output by the first battery pack to obtain a first current detection value, and detect the equalization current output by the second battery pack to obtain a second current detection value; a control unit, the control unit is respectively connected to the current detection unit, the first controllable switch unit and the second controllable switch unit, and the control unit is configured to control the first controllable switch unit and the second controllable switch unit according to the first current detection value and the second current detection value.

[0016] According to an embodiment of the present invention, the current detection unit includes: a first current detection module, which is disposed between the first controllable switch unit and the bidirectional equalization unit, and is configured to detect the equalization current output by the first battery pack to obtain a first current detection value; a second current detection module, which is disposed between the second controllable switch unit and the bidirectional equalization unit, and is configured to detect the equalization current output by the second battery pack to obtain a second current detection value.

[0017] According to an embodiment of the present invention, the first current detection module and the second current detection module each include a current transformer.

[0018] To achieve the above object, according to a second aspect embodiment of the present invention, a battery system is proposed, including: the battery equalization circuit of any one of the foregoing embodiments.

[0019] In the battery system according to the embodiment of the present invention, by adopting the above battery equalization circuit, bidirectional energy transfer of the battery pack is realized through the bidirectional equalization unit, and active equalization between any battery packs can be satisfied, thereby improving the efficiency of active equalization.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of a battery system according to an embodiment of the present invention;

[0022] Figure 2 is a circuit diagram of a battery equalization circuit according to an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of an energy circuit when a first battery cell releases electric energy according to an embodiment of the present invention;

[0024] Figure 4 is a schematic diagram of an energy circuit when a third battery cell is equally charged according to an embodiment of the present invention;

[0025] Figure 5 is a schematic diagram of an energy circuit when a second battery cell is equally charged according to an embodiment of the present invention;

[0026] Figure 6 is a schematic diagram of an energy circuit when a fourth battery cell is equally charged according to an embodiment of the present invention;

[0027] Figure 7Schematic diagram of the energy circuit when the third battery cell releases electrical energy according to an embodiment of the present utility model;

[0028] Figure 8 Circuit diagram of the battery equalization circuit according to another embodiment of the present utility model;

[0029] Figure 9 Schematic diagram of the energy circuit when the second battery cell releases electrical energy according to an embodiment of the present utility model. Detailed implementation manners

[0030] The embodiments of the present utility model will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present utility model, and should not be construed as limiting the present utility model.

[0031] The battery equalization circuit and the battery system of the embodiments of the present utility model will be described below with reference to the accompanying drawings.

[0032] Figure 1 Schematic diagram of the structure of a battery system according to an embodiment of the present utility model. As Figure 1 shown, the battery system includes a plurality of serially connected battery cells BAT1 - BAT4 and a battery equalization circuit 100, wherein the battery equalization circuit 100 is adapted to perform voltage equalization on the plurality of serially connected battery cells BAT1 - BAT4.

[0033] Specifically, the plurality of battery cells BAT1 - BAT4 form a first battery group 200 and a second battery group 300. The battery equalization circuit 100 transfers the excess electrical energy in the first battery group 200 and the excess electrical energy in the second battery group 300 to the battery with a lower charge, thereby solving the problem of battery inconsistency through the redistribution of energy.

[0034] Optionally, the plurality of battery cells BAT1 - BAT4 can be grouped according to the battery numbers. The battery cells with odd battery numbers form the first battery group 200, and the battery cells with even battery numbers form the second battery group 300. Taking Figure 1 as an example, 4 battery cells are numbered starting from the bottommost first battery cell. The number of the first battery cell BAT1 is 1, the number of the second battery cell BAT2 is 2, the number of the third battery cell BAT3 is 3, and the number of the fourth battery cell BAT4 is 4. Among them, the first battery cell BAT1 and the third battery cell BAT3 form the first battery group 200, and the second battery cell BAT2 and the fourth battery cell BAT4 form the second battery group 300.

[0035] It should be noted that the grouping method of battery cells is not limited to grouping according to odd and even numbers. Other grouping methods can also be adopted. For example, the first battery cell BAT1 and the second battery cell BAT2 can be grouped into the first battery pack 200, and the third battery cell BAT3 and the fourth battery cell BAT4 can be grouped into the second battery pack 300. The number of battery cells is not limited to 4 either. Figure 1 The 4 battery cells shown are exemplary and do not limit this application.

[0036] As Figure 1 shown, the battery equalization circuit 100 includes: a bidirectional equalization unit 10, a first controllable switch unit 20, and a second controllable switch unit 30.

[0037] Among them, one end of the first controllable switch unit 20 is adapted to be connected to the first battery pack 200 to supply the first electric energy released by the first battery pack 200 to the bidirectional equalization unit 10. One end of the second controllable switch unit 30 is adapted to be connected to the second battery pack 300 to supply the second electric energy released by the second battery pack 300 to the bidirectional equalization unit 10. The bidirectional equalization unit 10 is configured to perform isolation transformation on the first electric energy, and perform equalization charging on the second battery pack 300 according to the isolated and transformed first electric energy, and perform equalization charging on the first battery pack 200 according to the first electric energy, and perform isolation transformation on the second electric energy, and perform equalization charging on the first battery pack 200 according to the isolated and transformed second electric energy, and perform equalization charging on the second battery pack 300 according to the second electric energy.

[0038] Specifically, when there is excess first electric energy in the battery cells of the first battery pack 200, the first controllable switch unit 20 is turned on to release the first electric energy to the bidirectional equalization unit 10. The bidirectional equalization unit 10 performs isolation transformation on the first electric energy, and then uses the isolated and transformed first electric energy to equalize the battery cells in the second battery pack 300. Moreover, the bidirectional equalization unit 10 can also use the first electric energy to equalize the battery cells in the first battery pack 200. For example, if the first battery cell BAT1 has excess electric energy and the third battery cell BAT3 has a low charge level, the first controllable switch unit 20 can supply the first electric energy released by the first battery cell BAT1 to the bidirectional equalization unit 10, and the bidirectional equalization unit 10 performs equalization charging on the third battery cell BAT3 according to the first electric energy.

[0039] Similarly, when there is excess second electrical energy in the battery cells of the second battery pack 300, the second controllable switch unit 30 is turned on to release the second electrical energy to the bidirectional equalization unit 10. The bidirectional equalization unit 10 performs isolation transformation on the second electrical energy, and then uses the isolated and transformed second electrical energy to equalize the battery cells in the first battery pack 200. Moreover, the bidirectional equalization unit 10 can also use the second electrical energy to equalize the battery cells in the second battery pack 300.

[0040] In the above embodiment, the bidirectional equalization unit can use the excess electrical energy of the first battery pack to equalize the second battery pack and / or the first battery pack, and can also use the excess electrical energy of the second battery pack to equalize the first battery pack and / or the second battery pack, realizing bidirectional transfer of electrical energy, so as to meet the active equalization between any battery packs, thereby improving the efficiency of active equalization.

[0041] In some embodiments, as Figure 2 shown, the bidirectional equalization unit 10 includes: a transformer T. The transformer T includes a first winding N1, a second winding N2, a third winding N3, and a fourth winding N4. One end of the first winding N1 is connected to one end of the second winding N2 and has a first node J1. The other end of the first winding N1 and the other end of the second winding N2 are respectively connected to the negative electrodes of each battery cell in the first battery pack 200 through the first controllable switch unit 20. One end of the third winding N3 is connected to one end of the fourth winding N4 and has a second node J2. The other end of the third winding N3 and the other end of the fourth winding N4 are respectively connected to the negative electrodes of each battery cell in the second battery pack 300 through the second controllable switch unit 30. Among them, the first node J1 is connected to the positive electrode of each battery cell in the first battery pack 200 through the first controllable switch unit 20, and the second node J2 is connected to the positive electrode of each battery cell in the second battery pack 300 through the second controllable switch unit 30.

[0042] Specifically, the bidirectional equalization unit 10 adopts isolated bidirectional DC-DC buck-boost equalization. The isolation method uses a transformer T, which includes 4 windings, namely a first winding N1, a second winding N2, a third winding N3, and a fourth winding N4. The first winding N1 is used to input the first electric energy. The first winding N1 can couple the first electric energy to the fourth winding N4. The fourth winding N4 performs equalization charging on the second battery pack 300 according to the coupled electric energy. Moreover, since the second winding N2 is connected to the first winding N1, the second winding N2 can also perform equalization charging on the first battery pack 200 using the electric energy stored in the first winding N1. Similarly, the third winding N3 is used to input the second electric energy. The third winding N3 can couple the second electric energy to the second winding N2. The second winding N2 performs equalization charging on the first battery pack 200 according to the coupled electric energy. Moreover, since the third winding N3 and the fourth winding N4 are connected, the fourth winding N4 can also perform equalization charging on the first battery pack 200 using the electric energy stored in the third winding N3.

[0043] In some embodiments, as Figure 2 shown, the first controllable switch unit 20 includes: at least one first controllable switch module 21 and at least one second controllable switch module 22. Wherein, one end of each first controllable switch module 21 is adapted to be connected to the negative electrode of a battery cell in the first battery pack 200, and the other end of each first controllable switch module 21 is respectively connected to the other end of the first winding N1 and the other end of the second winding N2; one end of each second controllable switch module 22 is adapted to be connected to the positive electrode of a battery cell in the first battery pack 200, and the other end of each second controllable switch module 22 is connected to the first node J1.

[0044] Specifically, when at least one battery cell in the first battery pack 200 has excess energy, the corresponding first controllable switch module 21 and second controllable switch module 22 of this battery cell are controlled to be turned on to supply the excess electric energy of this battery cell to the first winding N1. When at least one battery cell in the first battery pack 200 needs to be equalized and charged, the corresponding first controllable switch module 21 and second controllable switch module 22 of this battery cell are controlled to be turned on to charge this battery cell according to the electric energy released by the second winding N2.

[0045] Taking Figure 2 shown as an example, assuming that the first battery cell BAT1 needs to equalize the third battery cell BAT3, the corresponding first controllable switch module 21 and second controllable switch module 22 of the first battery cell BAT1 are controlled to be turned on. The first battery cell BAT1 releases electric energy to the first winding N1. The energy loop is as Figure 3As shown, the current flows out from the positive electrode of the first battery cell BAT1, then passes through the second controllable switch module 22 corresponding to the first battery cell BAT1, the first winding N1, and the first controllable switch module 21 corresponding to the first battery cell BAT1, and finally flows into the negative electrode of the first battery cell BAT1. At this time, the first winding N1 stores energy. Then, the first controllable switch module 21 and the second controllable switch module 22 corresponding to the first battery cell BAT1 are controlled to turn off, and the first controllable switch module 21 and the second controllable switch module 22 corresponding to the third battery cell BAT3 are controlled to turn on. The second winding N2 performs equalizing charging on the third battery cell BAT3, and the energy loop is as Figure 4 shown. The current flows out from one end of the second winding N2, then passes through the second controllable switch module 22 corresponding to the third battery cell BAT3, the positive electrode of the third battery cell BAT3, the negative electrode of the third battery cell BAT3, and the first controllable switch module 21 corresponding to the third battery cell BAT3, and finally flows into the other end of the second winding N2.

[0046] In some embodiments, as Figure 2 shown, the second controllable switch unit 30 includes: at least one third controllable switch module 31 and at least one fourth controllable switch module 32. Wherein, one end of each third controllable switch module 31 is adapted to be connected to the negative electrode of a battery cell in the second battery pack 300, and the other end of each third controllable switch module 31 is respectively connected to the other end of the third winding N3 and the other end of the fourth winding N4; one end of each fourth controllable switch module 32 is adapted to be connected to the positive electrode of a battery cell in the second battery pack 300, and the other end of each fourth controllable switch module 32 is connected to the second node J2.

[0047] Similarly, when at least one battery cell in the second battery pack 300 has excess energy, the third controllable switch module 31 and the fourth controllable switch module 32 corresponding to the battery cell are controlled to turn on to provide the excess electric energy of the battery cell to the third winding N3. When at least one battery cell in the second battery pack 300 needs to be equalized and charged, the third controllable switch module 31 and the fourth controllable switch module 32 corresponding to the battery cell are controlled to turn on to charge the battery cell according to the electric energy released by the fourth winding N4.

[0048] Taking Figure 2 shown as an example, assuming that the first battery cell BAT1 needs to equalize the second battery cell BAT2, the first controllable switch module 21 and the second controllable switch module 22 corresponding to the first battery cell BAT1 are controlled to turn on, and the first battery cell BAT1 releases electric energy to the first winding N1. The energy loop is as Figure 3As shown. Then, control the first controllable switch module 21 and the second controllable switch module 22 corresponding to the first battery cell BAT1 to turn off, and control the third controllable switch module 31 and the fourth controllable switch module 32 corresponding to the second battery cell BAT2 to turn on. The fourth winding N4 performs equalizing charging on the second battery cell BAT2, and the energy loop is as Figure 5 shown. The current flows out from one end of the fourth winding N4, then flows through the fourth controllable switch module 32 corresponding to the second battery cell BAT2, the positive electrode of the second battery cell BAT2, the negative electrode of the second battery cell BAT2, the third controllable switch module 31 corresponding to the second battery cell BAT2, and finally flows into the other end of the fourth winding N4.

[0049] When the first battery cell BAT1 needs to equalize the fourth battery cell BAT4, the control method on the side of the first battery cell BAT1 is the same as that when the first battery cell BAT1 equalizes the second battery cell BAT2, which will not be elaborated here. Then, control the first controllable switch module 21 and the second controllable switch module 22 corresponding to the first battery cell BAT1 to turn off, and control the third controllable switch module 31 and the fourth controllable switch module 32 corresponding to the fourth battery cell BAT4 to turn on. The fourth winding N4 performs equalizing charging on the fourth battery cell BAT4, and the energy loop is as Figure 6 shown. The current flows out from one end of the fourth winding N4, then flows through the fourth controllable switch module 32 corresponding to the fourth battery cell BAT4, the positive electrode of the second battery cell BAT2, the negative electrode of the fourth battery cell BAT4, the third controllable switch module 31 corresponding to the second battery cell BAT2, and finally flows into the other end of the fourth winding N4.

[0050] When the third battery cell BAT3 needs to equalize the second battery cell BAT2, control the first controllable switch module 21 and the second controllable switch module 22 corresponding to the third battery cell BAT3 to turn on. The third battery cell BAT3 releases electric energy to the first winding N1, and the energy loop is as Figure 7 shown. The current flows out from the positive electrode of the third battery cell BAT3, then flows through the second controllable switch module 22 corresponding to the third battery cell BAT3, the first winding N1, the first controllable switch module 21 corresponding to the third battery cell BAT3, and finally flows into the negative electrode of the third battery cell BAT3. At this time, the first winding N1 stores energy. Then, control the first controllable switch module 21 and the second controllable switch module 22 corresponding to the third battery cell BAT3 to turn off, and control the third controllable switch module 31 and the fourth controllable switch module 32 corresponding to the second battery cell BAT2 to turn on. The energy loop is as Figure 5 shown.

[0051] When the third battery cell BAT3 needs to equalize the fourth battery cell BAT4, the control method on the side of the third battery cell BAT3 remains unchanged compared with when the third battery cell BAT3 equalizes the second battery cell BAT2, and the control method on the side of the fourth battery cell BAT4 remains unchanged compared with when the first battery cell BAT1 equalizes the fourth battery cell BAT4. Details are not elaborated here.

[0052] It should be noted that the equalization methods of the third battery cell BAT3 equalizing the first battery cell BAT1, the second battery cell BAT2 equalizing the fourth battery cell BAT4, the fourth battery cell BAT4 equalizing the second battery cell BAT2, and the first battery cell BAT1 equalizing the third battery cell BAT3 are the same. Details are not elaborated here.

[0053] In some embodiments, as Figure 2 shown, the first controllable switch module 21, the second controllable switch module 22, the third controllable switch module 31, and the fourth controllable switch module 32 each include at least one switching device.

[0054] It should be noted that the switching device can be a MOS (Metal-Oxide-Semiconductor Field-Effect Transistor) transistor, an IGBT (Insulate-Gate Bipolar Transistor), a relay, or other devices.

[0055] In some embodiments, as Figure 2 shown, there are two switching devices, the two switching devices are MOS transistors respectively, and the two MOS transistors are designed back-to-back.

[0056] It can be understood that the back-to-back design of the two MOS transistors can effectively prevent the current reverse flow phenomenon in the circuit. The MOS transistor can be an NMOS (N-Metal-Oxide-Semiconductor) transistor or a PMOS (P-Metal-Oxide-Semiconductor) transistor. There is no specific limitation here. When the MOS transistor is an NMOS transistor, the sources of the two NMOS transistors are connected; when the MOS transistor is a PMOS transistor, the drains of the two PMOS transistors are connected.

[0057] In some embodiments, as Figure 2 shown, the first winding N1 and the third winding N3 are low-voltage windings respectively, and the second winding N2 and the fourth winding N4 are high-voltage windings respectively.

[0058] Specifically, since the first winding N1 and the third winding N3 are low-voltage windings, and the second winding N2 and the fourth winding N4 are high-voltage windings, the second winding N2 and the fourth winding N4 will boost the voltage, thereby increasing the equalizing charging current. The boosting amplitude of the voltage is determined according to the turns ratio of the low-voltage winding to the high-voltage winding.

[0059] In the above embodiment, the second winding and the fourth winding can increase the charging voltage, thereby increasing the equalizing charging current, which can shorten the equalizing time and further improve the equalizing efficiency.

[0060] In some embodiments, as Figure 2 shown, the bidirectional equalizing unit 10 further includes: a fifth controllable switch module 11, a sixth controllable switch module 12, a seventh controllable switch module 13, and an eighth controllable switch module 14. Among them, one end of the fifth controllable switch module 11 is connected to the other end of the first winding N1, and the other end of the fifth controllable switch module 11 is connected to the negative electrode of each battery cell in the first battery pack 200 through the first controllable switch unit 20; one end of the sixth controllable switch module 12 is connected to the other end of the second winding N2, and the other end of the sixth controllable switch module 12 is connected to the negative electrode of each battery cell in the first battery pack 200 through the first controllable switch unit 20; one end of the seventh controllable switch module 13 is connected to the other end of the third winding N3, and the other end of the seventh controllable switch module 13 is connected to the negative electrode of each battery cell in the second battery pack 300 through the second controllable switch unit 30; one end of the eighth controllable switch module 14 is connected to the other end of the fourth winding N4, and the other end of the eighth controllable switch module 14 is connected to the negative electrode of each battery cell in the second battery pack 300 through the second controllable switch unit 30.

[0061] Specifically, the transformer T can be controlled to store or release energy through the fifth controllable switch module 11, the sixth controllable switch module 12, the seventh controllable switch module 13, and the eighth controllable switch module 14. When the first battery pack 200 releases electrical energy, the fifth controllable switch module 11 is controlled to turn on, and the first winding N1 stores electrical energy; when the first battery pack 200 is equally charged, the sixth controllable switch module 12 is controlled to turn on, and the second winding N2 releases electrical energy; when the second battery pack 300 releases electrical energy, the seventh controllable switch module 13 is controlled to turn on, and the third winding N3 stores electrical energy; when the second battery pack 300 is equally charged, the eighth controllable switch module 14 is controlled to turn on, and the fourth winding N4 releases electrical energy.

[0062] It should be noted that the circuits of the fifth controllable switch module 11, the sixth controllable switch module 12, the seventh controllable switch module 13, and the eighth controllable switch module 14 can be the same as those of the first controllable switch module 21, the second controllable switch module 22, the third controllable switch module 31, and the fourth controllable switch module 32. For example, the fifth controllable switch module 11, the sixth controllable switch module 12, the seventh controllable switch module 13, and the eighth controllable switch module 14 each include two NMOS transistors, and the two NMOS transistors are designed back-to-back.

[0063] In some embodiments, the battery equalization circuit 100 further includes: a current detection unit and a control unit (not shown). The current detection unit is adapted to detect the equalization current output by the first battery pack 200 to obtain a first current detection value, and detect the equalization current output by the second battery pack 300 to obtain a second current detection value. The control unit is respectively connected to the current detection unit, the first controllable switch unit 20, and the second controllable switch unit 30. The control unit is configured to control the first controllable switch unit 20 and the second controllable switch unit 30 according to the first current detection value and the second current detection value.

[0064] Specifically, when the first battery pack 200 releases the first electric energy, the current detection unit detects the current output by the first battery pack 200 to obtain a first current detection value; when the second battery pack 300 releases the second electric energy, the current detection unit detects the current output by the second battery pack 300 to obtain a second current detection value. The voltage of the equalization charge, that is, the output voltage of the transformer T, can be calculated according to the following formula:

[0065]

[0066] Wherein, Vo is the voltage of the equalization charge, Vin is the input voltage of the transformer T, T0 is the energy storage time of the transformer T, T1 is the energy release time of the transformer T, and n is the turn ratio of the low-voltage winding to the high-voltage winding.

[0067] Therefore, the control unit can perform power monitoring according to the first current sampling value, the second current sampling value, and the voltage of the equalization charge, and adjust the duty cycles of the first controllable switch module 21, the second controllable switch module 22, the third controllable switch module 31, the fourth controllable switch module 32, the fifth controllable switch module 11, the sixth controllable switch module 12, the seventh controllable switch module 13, and the eighth controllable switch module 14 according to the power, so as to achieve power closed-loop control and thus reach the maximum equalization current.

[0068] In the above embodiments, the control unit can achieve power closed-loop control of the first controllable switch unit and the second controllable switch unit according to the first current detection value and the second current detection value, so as to reach the maximum equalization current and further shorten the equalization time.

[0069] In some embodiments, as Figure 8 shown, the current detection unit includes: a first current detection module 41 and a second current detection module 42. Among them, the first current detection module 41 is disposed between the first controllable switch unit 20 and the bidirectional equalization unit 10, and the first current detection module 41 is configured to detect the equalization current output by the first battery pack 200 to obtain a first current detection value; the second current detection module 42 is disposed between the second controllable switch unit 30 and the bidirectional equalization unit 10, and the second current detection module 42 is configured to detect the equalization current output by the second battery pack 300 to obtain a second current detection value.

[0070] Specifically, when the first controllable switch unit 20 is turned on, the first battery pack 200 releases first electric energy to the bidirectional equalization unit 10 through the first current detection module 41, and the first current detection module 41 detects the equalization current output by the first battery pack 200; when the second controllable switch unit 30 is turned on, the second battery pack 300 releases second electric energy to the bidirectional equalization unit 10 through the first current detection module 41, and the second current detection module 42 detects the equalization current output by the second battery pack 300. The output ends of the first current detection module 41 and the second current detection module 42 are also connected to the control unit to provide the first current detection value and the second current detection value to the control unit.

[0071] Furthermore, in some embodiments, the first current detection module 41 and the second current detection module 42 each include a current transformer.

[0072] It should be noted that the first current detection module 41 and the second current detection module 42 are not limited to using current transformers for current detection, and other methods can also be used for current detection, such as using a sampling resistor for current sampling, which is not specifically limited here.

[0073] The technical solution of the present application will be further described in detail below in combination with specific embodiments:

[0074] The battery equalization circuit 100 as Figure 8As shown, the first controllable switch module 21 corresponding to the first battery cell BAT1 includes two back-to-back first switching transistors Q1, the second controllable switch module 22 corresponding to the first battery cell BAT1 includes two back-to-back second switching transistors Q2, the third controllable switch module 31 corresponding to the second battery cell BAT2 includes two back-to-back third switching transistors Q3, the fourth controllable switch module 32 corresponding to the second battery cell BAT2 includes two back-to-back fourth switching transistors Q4, the first controllable switch module 21 corresponding to the third battery cell BAT3 includes two back-to-back fifth switching transistors Q5, the second controllable switch module 22 corresponding to the first battery cell BAT1 includes two back-to-back sixth switching transistors Q6, the third controllable switch module 31 corresponding to the fourth battery cell BAT4 includes two back-to-back seventh switching transistors Q7, the fourth controllable switch module 32 corresponding to the second battery cell BAT2 includes two back-to-back eighth switching transistors Q8, the fifth controllable switch module 11 includes two back-to-back ninth switching transistors Q9, the sixth controllable switch module 12 includes two back-to-back tenth switching transistors Q10, the seventh controllable switch module 13 includes two back-to-back eleventh switching transistors Q11, the eighth controllable switch module 14 includes two back-to-back twelfth switching transistors Q12. Among them, the first switching transistor Q1 to the twelfth switching transistor Q12 are all NMOS transistors. The first current detection module 41 includes a first current transformer IC1, and the second current detection module 42 includes a second current transformer IC2.

[0075] Assume that the first battery cell BAT1 equalizes the second battery cell BAT2. The control unit first controls the first switching transistor Q1, the second switching transistor Q2, and the ninth switching transistor Q9 to turn on. The first battery cell BAT1 releases electrical energy to the first winding N1, and the transformer T stores energy. The energy circuit is as Figure 3 shown. At this time, the first current transformer IC1 detects the equalization current output by the first battery cell BAT1. Then the control unit controls the ninth switching transistor Q9 to turn off, and controls the twelfth switching transistor Q12, the third switching transistor Q3, and the fourth switching transistor Q4 to turn on. The first winding N1 couples the first electrical energy to the fourth winding N4. Since the fourth winding N4 is a high-voltage winding, the voltage output by the fourth winding N4 increases, and the fourth winding N4 equalizes and charges the second battery cell BAT2. The energy circuit is as Figure 5 shown.

[0076] Assume that the first battery cell BAT1 equalizes the fourth battery cell BAT4. The control unit first controls the first switching transistor Q1, the second switching transistor Q2, and the ninth switching transistor Q9 to turn on. The first battery cell BAT1 releases electrical energy to the first winding N1, and the transformer T stores energy. The energy circuit is as Figure 3As shown, at this time, the first current transformer IC1 detects the balancing current output by the first battery cell BAT1. Then, the control unit controls the ninth switch tube Q9 to turn off, and controls the twelfth switch tube Q12, the seventh switch tube Q7, and the eighth switch tube Q8 to turn on. The first winding N1 couples the first electrical energy to the fourth winding N4. Since the fourth winding N4 is a high-voltage winding, the voltage output by the fourth winding N4 increases, and the fourth winding N4 performs balancing charging on the fourth battery cell BAT4. The energy loop is as Figure 6 shown.

[0077] Assume that the third battery cell BAT3 balances the second battery cell BAT2. The control unit first controls the fifth switch tube Q5, the sixth switch tube Q6, and the ninth switch tube Q9 to turn on. The third battery cell BAT3 releases electrical energy to the first winding N1, and the transformer T stores energy. The energy loop is as Figure 7 shown. At this time, the first current transformer IC1 detects the balancing current output by the third battery cell BAT3. Then, the control unit controls the ninth switch tube Q9 to turn off, and controls the twelfth switch tube Q12, the third switch tube Q3, and the fourth switch tube Q4 to turn on. The first winding N1 couples the second electrical energy to the fourth winding N4. Since the fourth winding N4 is a high-voltage winding, the voltage output by the fourth winding N4 increases, and the fourth winding N4 performs balancing charging on the second battery cell BAT2. The energy loop is as Figure 5 shown.

[0078] Assume that the third battery cell BAT3 balances the fourth battery cell BAT4. The control unit first controls the fifth switch tube Q5, the sixth switch tube Q6, and the ninth switch tube Q9 to turn on. The third battery cell BAT3 releases electrical energy to the first winding N1, and the transformer T stores energy. The energy loop is as Figure 7 shown. At this time, the first current transformer IC1 detects the balancing current output by the third battery cell BAT3. Then, the control unit controls the ninth switch tube Q9 to turn off, and controls the twelfth switch tube Q12, the seventh switch tube Q7, and the eighth switch tube Q8 to turn on. The first winding N1 couples the first electrical energy to the fourth winding N4. Since the fourth winding N4 is a high-voltage winding, the voltage output by the fourth winding N4 increases, and the fourth winding N4 performs balancing charging on the fourth battery cell BAT4. The energy loop is as Figure 6 shown.

[0079] Assume that the first battery cell BAT1 balances the third battery cell BAT3. The control unit first controls the first switch tube Q1, the second switch tube Q2, and the ninth switch tube Q9 to turn on. The first battery cell BAT1 releases electrical energy to the first winding N1, and the transformer T stores energy. The energy loop is as Figure 3As shown, at this time, the first current transformer IC1 detects the equalization current output by the first battery cell BAT1. Then, the control unit controls the ninth switch tube Q9 and the second switch tube Q2 to turn off, and controls the tenth switch tube Q10, the sixth switch tube Q6, and the seventh switch tube Q7 to turn on. The first winding N1 supplies the first electrical energy to the second winding N2. Since the second winding N2 is a high-voltage winding, the voltage output by the second winding N2 increases, and the second winding N2 performs equalization charging on the third battery cell BAT3. The energy loop is as Figure 4 shown.

[0080] Assume that the second battery cell BAT2 equalizes the fourth battery cell BAT4. The control unit first controls the third switch tube Q3, the fourth switch tube Q4, and the eleventh switch tube Q11 to turn on. The second battery cell BAT2 releases electrical energy to the third winding N3, and the transformer T stores energy. The energy loop is as Figure 9 shown. At this time, the second current transformer IC2 detects the equalization current output by the second battery cell BAT2. Then, the control unit controls the fourth switch tube Q4 and the eleventh switch tube Q11 to turn off, and controls the twelfth switch tube Q12, the seventh switch tube Q7, and the eighth switch tube Q8 to turn on. The first winding N1 couples the first electrical energy to the fourth winding N4. Since the fourth winding N4 is a high-voltage winding, the voltage output by the fourth winding N4 increases, and the fourth winding N4 performs equalization charging on the fourth battery cell BAT4. The energy loop is as Figure 6 shown.

[0081] In the above embodiment, by multiplexing the bidirectional equalization unit, active equalization between any battery packs is achieved. Moreover, the multiplexing bidirectional equalization unit can effectively reduce the product cost and also reduce the product volume, thereby achieving a greater power equalization ability under the same volume. Further, the battery equalization circuit of this embodiment adopts an isolated equalization method, and the isolated equalization method has stronger anti-interference ability, so that the application range of the battery equalization circuit is wider.

[0082] In summary, according to the battery equalization circuit of the embodiment of the present invention, it includes a bidirectional equalization unit, a first controllable switch unit, and a second controllable switch unit. Wherein, one end of the first controllable switch unit is adapted to be connected to the first battery pack to provide the first electric energy released by the first battery pack to the bidirectional equalization unit, and one end of the second controllable switch unit is adapted to be connected to the second battery pack to provide the second electric energy released by the second battery pack to the bidirectional equalization unit. The bidirectional equalization unit is configured to perform isolation transformation on the first electric energy, and perform equalization charging on the second battery pack according to the isolated and transformed first electric energy, and perform equalization charging on the first battery pack according to the first electric energy, and perform isolation transformation on the second electric energy, and perform equalization charging on the first battery pack according to the isolated and transformed second electric energy, and perform equalization charging on the second battery pack according to the second electric energy. Thus, the bidirectional equalization unit can perform equalization charging on the first battery pack and the second battery pack according to the redundant electric energy of the first battery pack, or perform equalization charging on the first battery pack and the second battery pack according to the redundant electric energy of the second battery pack, realizing the bidirectional energy transfer of the battery packs, so as to meet the active equalization between any battery packs, thereby improving the efficiency of active equalization; and, the transformer in the bidirectional equalization unit can increase the charging voltage, thereby increasing the equalization charging current, which can shorten the equalization time and further improve the equalization efficiency.

[0083] Corresponding to the above embodiment, an embodiment of the present invention also provides a battery system. As Figure 1 shown, the battery system includes: the battery equalization circuit 100 of any one of the foregoing embodiments.

[0084] According to the battery system of the embodiment of the present invention, by adopting the above battery equalization circuit, the bidirectional energy transfer of the battery packs is realized through the bidirectional equalization unit, and the active equalization between any battery packs can be satisfied, thereby improving the efficiency of active equalization.

[0085] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0086] In addition, the terms "first", "second", etc. used in the embodiments of the present utility model are only for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features indicated in this embodiment. Thus, the features defined with the terms "first", "second", etc. in the embodiments of the present utility model may explicitly or implicitly indicate that at least one such feature is included in this embodiment. In the description of the present utility model, the meaning of the word "plural" is at least two or more than two, such as two, three, four, etc., unless otherwise explicitly and specifically defined in the embodiment.

[0087] In the present utility model, unless otherwise explicitly specified or limited in the embodiments, the terms "mounted", "connected", "coupled" and "fixed" etc. appearing in the embodiments shall be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or integrated. Understandably, it can also be a mechanical connection, an electrical connection, etc.; of course, it can also be directly connected, or indirectly connected through an intermediate medium, or it can be the communication inside two components, or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to the specific implementation circumstances.

[0088] Although the embodiments of the present utility model have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limiting the present utility model. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present utility model.

Claims

1. A battery balancing circuit, characterized in that: The battery balancing circuit is suitable for voltage balancing of a plurality of battery cells connected in series, wherein the plurality of battery cells constitute a first battery group and a second battery group, and the battery balancing circuit comprises: a bidirectional balancing unit, a first controllable switch unit and a second controllable switch unit, wherein one end of the first controllable switch unit is suitable for connecting the first battery group to provide the first electric energy released by the first battery group to the bidirectional balancing unit, and one end of the second controllable switch unit is suitable for connecting the second battery group to provide the second electric energy released by the second battery group to the bidirectional balancing unit, and the bidirectional balancing unit is configured to perform isolation transformation on the first electric energy, and perform balanced charging on the second battery group according to the first electric energy after isolation transformation, and perform balanced charging on the first battery group according to the first electric energy, and perform isolation transformation on the second electric energy, and perform balanced charging on the first battery group according to the second electric energy after isolation transformation, and perform balanced charging on the second battery group according to the second electric energy.

2. The battery equalization circuit according to claim 1, characterized in that: The bidirectional balancing unit comprises: A transformer, the transformer comprising a first winding, a second winding, a third winding and a fourth winding, one end of the first winding being connected to one end of the second winding and having a first node, the other end of the first winding and the other end of the second winding being connected to the negative electrode of each battery cell in the first battery group through the first controllable switch unit, one end of the third winding being connected to one end of the fourth winding and having a second node, the other end of the third winding and the other end of the fourth winding being connected to the negative electrode of each battery cell in the second battery group through the second controllable switch unit, wherein the first node is connected to the positive electrode of each battery cell in the first battery group through the first controllable switch unit, and the second node is connected to the positive electrode of each battery cell in the second battery group through the second controllable switch unit.

3. The battery equalization circuit according to claim 2, characterized in that: The first controllable switch unit comprises: At least one first controllable switch module, one end of each of the first controllable switch modules is suitable for connecting to the negative electrode of a battery cell in the first battery pack, and the other end of each of the first controllable switch modules is respectively connected to the other end of the first winding and the other end of the second winding; At least one second controllable switch module, one end of each of the second controllable switch modules is suitable for connecting to the positive electrode of a battery cell in the first battery group, and the other end of each of the second controllable switch modules is connected to the first node.

4. The battery equalization circuit according to claim 3, characterized in that: The second controllable switch unit comprises: At least one third controllable switch module, one end of each of the third controllable switch modules is suitable for connecting to the negative electrode of a battery cell in the second battery pack, and the other end of each of the third controllable switch modules is respectively connected to the other end of the third winding and the other end of the fourth winding; At least one fourth controllable switch module, one end of each of the fourth controllable switch modules is suitable for connecting to the positive electrode of a battery cell in the second battery pack, and the other end of each of the fourth controllable switch modules is connected to the second node.

5. The battery equalization circuit according to claim 4, characterized in that: The first controllable switch module, the second controllable switch module, the third controllable switch module and the fourth controllable switch module respectively include at least one switch device.

6. The battery equalization circuit according to claim 5, characterized in that: There are two switch devices, each of which is a MOS tube, and the two MOS tubes are designed back to back.

7. The battery equalization circuit according to any one of claims 2 to 6, characterized in that: The first winding and the third winding are low-voltage windings, respectively, and the second winding and the fourth winding are high-voltage windings, respectively.

8. The battery equalization circuit according to any one of claims 2 to 6, characterized in that: The bidirectional balancing unit also includes: a fifth controllable switch module, one end of which is connected to the other end of the first winding, and the other end of which is connected to the negative electrode of each battery cell in the first battery pack through the first controllable switch unit; a sixth controllable switch module, one end of which is connected to the other end of the second winding, and the other end of which is connected to the negative electrode of each battery cell in the first battery pack through the first controllable switch unit; a seventh controllable switch module, one end of the seventh controllable switch module being connected to the other end of the third winding, and the other end of the seventh controllable switch module being connected to the negative electrode of each battery cell in the second battery pack through the second controllable switch unit; An eighth controllable switch module, one end of which is connected to the other end of the fourth winding, and the other end of which is connected to the negative electrode of each battery cell in the second battery pack through the second controllable switch unit.

9. The battery equalization circuit according to claim 1, characterized in that: Also includes: a current detection unit, adapted to detect the balancing current output by the first battery group to obtain a first current detection value, and to detect the balancing current output by the second battery group to obtain a second current detection value; A control unit, wherein the control unit is respectively connected to the current detection unit, the first controllable switch unit and the second controllable switch unit, and the control unit is configured to control the first controllable switch unit and the second controllable switch unit according to the first current detection value and the second current detection value.

10. The battery equalization circuit according to claim 9, characterized in that: The current detection unit comprises: a first current detection module, which is disposed between the first controllable switch unit and the bidirectional balancing unit, and is configured to detect the balancing current output by the first battery pack to obtain the first current detection value; A second current detection module, wherein the second current detection module is disposed between the second controllable switch unit and the bidirectional balancing unit, and the second current detection module is configured to detect the balancing current output by the second battery pack to obtain the second current detection value.

11. The battery equalization circuit according to claim 10, characterized in that: The first current detection module and the second current detection module respectively include a current transformer.

12. A battery system, characterized in that: include: The battery equalization circuit according to any one of claims 1 to 11.

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