Battery equalization circuit and energy storage system

Abstract

The utility model discloses a battery equalization circuit and an energy storage system, and the circuit comprises a battery pack which comprises a plurality of single batteries which are connected in series; a first half-bridge circuit; the plurality of second half-bridge circuits are arranged in one-to-one correspondence with the single batteries, and the second half-bridge circuits are connected in parallel with the corresponding single batteries; and the transformer comprises a primary coil and secondary coils arranged in one-to-one correspondence with the second half-bridge circuits, the primary coil is connected with the first half-bridge circuit, and the secondary coils are connected with the second half-bridge circuits. According to the utility model, the equalization technology is simplified, the equalization efficiency is greatly improved, the circuit structure is simple, and the cost of the equalization scheme is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of energy storage, and in particular to a battery equalization circuit and an energy storage system. Background Art

[0002] In the energy storage system, it is necessary to connect single lithium batteries in series to form battery packs with different voltages and capacities for use. After the single batteries are connected in series, due to the differences of each single battery, the voltage and capacity of each single battery are different during the use of the battery, and this difference will become larger and larger with changes in the environment and the increase in usage time. During the charging process of the battery pack, due to the barrel effect, the single battery with the lowest capacity will limit the overall charging of the battery pack, resulting in a reduction in the overall capacity. In order to solve the above problems, a balancing function is generally added to the design of the protection board or battery management system. The main function of balancing is to consume or transfer the power of the single battery that is fully charged in advance during the charging process, so that other single batteries that have not been fully charged or discharged can continue to charge, thereby ensuring that the battery pack as a whole can be charged more fully.

[0003] At present, the balancing schemes include passive balancing and active balancing. Passive balancing is also called energy dissipation balancing. The working principle is to connect a resistor in parallel to each single cell. When a single cell has been fully charged in advance and the battery pack needs to continue to be charged, a resistor is connected to discharge it and consume the excess energy. In this way, more charging time can be gained for other single cells before the battery charging protection. Active balancing is also called non-energy dissipation balancing. Its principle is to transfer the energy in the single cell that is fully charged in advance to the single cell that has not been fully charged, so as to ensure that each single cell in the battery pack can be fully charged. This active balancing scheme can also play a balancing role in the discharge process of the battery pack because it does not consume the battery capacity. However, the current balancing scheme is too costly, technically complex and has low balancing efficiency. Utility Model Content

[0004] The utility model provides a battery equalization circuit and an energy storage system to solve the problems of high cost, complex technology and low equalization efficiency of current equalization solutions.

[0005] In a first aspect, the utility model provides a battery balancing circuit, the circuit comprising:

[0006] A battery pack, comprising a plurality of single cells connected in series;

[0007] A first half-bridge circuit;

[0008] A plurality of second half-bridge circuits are arranged corresponding to the single cells one by one, and the second half-bridge circuits are connected in parallel with the corresponding single cells;

[0009] The transformer comprises a primary coil and a secondary coil arranged in one-to-one correspondence with the second half-bridge circuit, the primary coil is connected to the first half-bridge circuit, and the secondary coil is connected to the second half-bridge circuit.

[0010] In a second aspect, the utility model provides an energy storage system, which includes a plurality of battery packs, each of which includes a plurality of single cells connected in series; the battery packs are balanced by the battery balancing circuit provided in the first aspect.

[0011] The technical solution of the utility model provides a battery balancing circuit and an energy storage system. By setting a first half-bridge circuit, a second half-bridge circuit and a transformer, the power balance of the single cells in the battery pack can be achieved when the power difference of the single cells in the battery pack is greater than or equal to a threshold value and when the power difference of the single cells in the battery pack is less than the threshold value. The balancing scheme of the embodiment of the utility model belongs to an active balancing scheme, which can achieve balancing during the charging process of the battery pack and also during the discharging process of the battery pack. The balancing technology is simplified and the balancing efficiency is greatly improved through the autonomous cooperation of various circuit modules. At the same time, the circuit structure is simple, which reduces the cost of the balancing scheme.

[0012] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present utility model, nor are they intended to limit the scope of the present utility model. Other features of the present utility model will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0014] Figure 1 It is a structural schematic diagram of a battery balancing circuit provided by an embodiment of the utility model;

[0015] Figure 2 It is a structural schematic diagram of another battery balancing circuit provided by an embodiment of the utility model;

[0016] Figure 3 It is a structural schematic diagram of another battery balancing circuit provided by an embodiment of the utility model. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0018] It should be noted that the terms "first", "second", etc. in the specification and claims of the utility model and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the utility model described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0019] Figure 1 Schematic diagram of a battery balancing circuit provided by an embodiment of the utility model. Figure 1 As shown, the circuit includes:

[0020] The battery pack 1 comprises a plurality of single cells BAT1-BATn connected in series; a first half-bridge circuit 2; and a plurality of second half-bridge circuits 3, which are arranged one by one corresponding to the single cells BAT1-BATn, and the second half-bridge circuits 3 are connected in parallel with the corresponding single cells BAT1-BATn.

[0021] The transformer T1 includes a primary coil and a secondary coil arranged in one-to-one correspondence with the second half-bridge circuit 3 . The primary coil is connected to the first half-bridge circuit 2 , and the secondary coil is connected to the second half-bridge circuit 3 .

[0022] Specifically, the battery balancing circuit includes a battery pack 1, the battery pack 1 includes a plurality of single cells BAT1-BATn, and the plurality of single cells BAT1-BATn are connected in series. The battery balancing circuit also includes a first half-bridge circuit 2 and a plurality of second half-bridge circuits 3, the second half-bridge circuits 3 are arranged in one-to-one correspondence with the single cells BAT1-BATn, and are connected in parallel with the corresponding single cells BAT1-BATn.

[0023] The battery balancing circuit also includes a transformer T1, which includes a primary coil and multiple secondary coils. The secondary coils are arranged in a one-to-one correspondence with the second half-bridge circuit 3 and are connected to the second half-bridge circuit 3. One end of the secondary coil is connected to the second half-bridge circuit 3 and is commonly connected to the positive electrode of the corresponding single battery BAT1-BATn. The primary coil is connected to the first half-bridge circuit 2, and one end of the primary coil is connected to the positive electrode of the battery pack 1.

[0024] The power difference of the single cells BAT1-BATn in the battery pack 1 is compared with the threshold value. In the embodiment of the utility model, the threshold value is preset according to actual needs and is used to determine the degree of power difference of the single cells BAT1-BATn. The power difference of the single cells BAT1-BATn in the battery pack 1 can be compared with the threshold value after the battery pack 1 is charged or discharged for a preset time, when the battery pack 1 is static. When the power difference of the single cells BAT1-BATn in the battery pack 1 is greater than or equal to the threshold value, that is, when the power difference between the single cell BAT1-BATn with the largest power and the single cell BAT1-BATn with the smallest power in the battery pack 1 is greater than or equal to the threshold value, one end of the primary coil of the transformer T1 is connected to the positive pole of the battery pack 1, and the first half-bridge circuit 2 controls the battery pack 1 to charge the primary coil, and controls the charging circuit to be disconnected after charging for a certain period of time, and the primary coil generates an induced voltage, and the opposite-name end of the primary coil is the positive pole, and the same-name end is the negative pole. The secondary coil of the transformer T1 also generates an induced voltage, and the opposite-name end is the positive pole and the same-name end is the negative pole. The single battery BAT1-BATn with the lowest power is determined, and the second half-bridge circuit 3 corresponding to the single battery BAT1-BATn with the lowest power controls the secondary coil corresponding to it to charge the single battery BAT1-BATn with the lowest power, and the second half-bridge circuit 3 corresponding to the remaining single batteries BAT1-BATn controls the secondary coil corresponding to it not to charge the remaining single batteries BAT1-BATn.

[0025] When the power difference of the single cells BAT1-BATn in the battery pack 1 is less than the threshold value, that is, when the power difference between the single cell BAT1-BATn with the highest power and the single cell BAT1-BATn with the lowest power in the battery pack 1 is less than the threshold value, the power difference of the single cells BAT1-BATn is small at this time, but in order to further improve the service life of the battery pack 1, the power of the single cells BAT1-BATn in the battery pack 1 continues to be balanced. The single cell BAT1-BATn with the highest power is determined, and the second half-bridge circuit 3 corresponding to it controls the single cell BAT1-BATn with the highest power to charge the secondary coil, and this secondary coil is the secondary coil corresponding to the above-mentioned second half-bridge circuit 3. After charging for a certain period of time, the charging circuit is controlled to be disconnected. At this time, the secondary coil generates an induced electromotive force, and the same-name end is the positive pole, and the opposite-name end is the negative pole. The primary coil of the transformer T1 also generates an induced electromotive force, and the same-name end is the positive pole, and the opposite-name end is the negative pole. The first half-bridge circuit 2 controls the primary coil to charge the battery pack 1 , so as to achieve charge balance of the single cells BAT1 -BATn in the battery pack 1 .

[0026] The technical solution of the embodiment of the utility model provides a battery balancing circuit. By setting a first half-bridge circuit, a second half-bridge circuit and a transformer, the battery power difference of the single cells in the battery pack can be equalized when the battery power difference of the single cells in the battery pack is greater than or equal to a threshold value and when the battery power difference of the single cells in the battery pack is less than the threshold value. The balancing scheme of the embodiment of the utility model belongs to an active balancing scheme, which can achieve balancing during the charging process of the battery pack and also during the discharging process of the battery pack. The balancing technology is simplified and the balancing efficiency is greatly improved through the autonomous cooperation of various circuit modules. At the same time, the circuit structure is simple, which reduces the cost of the balancing scheme.

[0027] Figure 2 1 is a schematic diagram of another battery balancing circuit provided by an embodiment of the present utility model. Figure 2 As shown, the circuit also includes: a control circuit 4 and a drive circuit 5.

[0028] The control circuit 4 is connected to the driving circuit 5 and is used to control the driving circuit 5 to output an on signal or an off signal.

[0029] The driving circuit 5 is connected to the first half-bridge circuit 2 and the second half-bridge circuit 3 , and is used for outputting an on signal or an off signal to the first half-bridge circuit 2 and the second half-bridge circuit 3 .

[0030] Specifically, the battery balancing circuit may further include a control circuit 4 and a drive circuit 5. The control circuit 4 is connected to the drive circuit 5, and the drive circuit 5 is connected to the first half-bridge circuit 2 and the second half-bridge circuit 3. The drive circuit 5 may output both an on signal and an off signal to the first half-bridge circuit 2 at the same time, respectively controlling different switch elements in the first half-bridge circuit 2. The drive circuit 5 may output both an on signal and an off signal to the second half-bridge circuit 3 at the same time, respectively controlling different switch elements in the second half-bridge circuit 3.

[0031] When the power difference of the single cells BAT1-BATn in the battery pack 1 is greater than or equal to the threshold, that is, when the power difference between the single cell BAT1-BATn with the largest power and the single cell BAT1-BATn with the smallest power in the battery pack 1 is greater than or equal to the threshold, the control circuit 4 outputs a first control signal to the drive circuit 5, and the drive circuit 5 outputs a conduction signal or a cutoff signal to the first half-bridge circuit 2 and the second half-bridge circuit 3 according to the first control signal, so that the first half-bridge circuit 2 controls the battery pack 1 to charge the primary coil, and controls the charging circuit to be disconnected after charging for a certain period of time. The second half-bridge circuit 3 corresponding to the single cell BAT1-BATn with the lowest power controls the secondary coil corresponding to it to charge the single cell BAT1-BATn with the lowest power, and the second half-bridge circuit 3 corresponding to the remaining single cells BAT1-BATn controls the secondary coil corresponding to it not to charge the remaining single cells BAT1-BATn.

[0032] When the power difference of the single cells BAT1-BATn in the battery pack 1 is less than the threshold value, that is, when the power difference between the single cells BAT1-BATn with the highest power and the single cells BAT1-BATn with the lowest power in the battery pack 1 is less than the threshold value, the control circuit 4 outputs a second control signal to the drive circuit 5, and the drive circuit 5 outputs a conduction signal or a cutoff signal to the first half-bridge circuit 2 and the second half-bridge circuit 3 according to the second control signal, so that the second half-bridge circuit 3 corresponding to the single cells BAT1-BATn with the highest power controls the single cells BAT1-BATn with the highest power to charge the secondary coil, and this secondary coil is the secondary coil corresponding to the second half-bridge circuit 3. And after charging for a certain period of time, the charging circuit is controlled to be disconnected. And the first half-bridge circuit 2 controls the primary coil to charge the battery pack 1, so as to realize the power balance of the single cells BAT1-BATn in the battery pack 1.

[0033] Figure 3 1 is a schematic diagram of another battery balancing circuit provided by an embodiment of the present utility model. Figure 3 As shown, the first half-bridge circuit 2 includes a first switch unit 21 and a second switch unit 22 ; the second half-bridge circuit 3 includes a third switch unit 31 and a fourth switch unit 32 .

[0034] The driving circuit 5 is connected to the control end of the first switch unit 21, the control end of the second switch unit 22, the control end of the third switch unit 31 and the control end of the fourth switch unit 32, and is used to output a turn-on signal or a turn-off signal to the control end of the first switch unit 21, the control end of the second switch unit 22, the control end of the third switch unit 31 and the control end of the fourth switch unit 32.

[0035] Specifically, the first half-bridge circuit 2 may include a first switch unit 21 and a second switch unit 22, and the second half-bridge circuit may include a third switch unit 31 and a fourth switch unit 32. The drive circuit 5 may be connected to the control end of the first switch unit 21, the control end of the second switch unit 22, the control end of the third switch unit 31, and the control end of the fourth switch unit 32, and output a turn-on signal or a turn-off signal to the control end of the first switch unit 21, the control end of the second switch unit 22, the control end of the third switch unit 31, and the control end of the fourth switch unit 32, respectively controlling the first switch unit 21, the second switch unit 22, the third switch unit 31, and the fourth switch unit 32 to be turned on or off. The turn-on signal may control the first switch unit 21, the second switch unit 22, the third switch unit 31, and the fourth switch unit 32 to be turned on, and the turn-off signal may control the first switch unit 21, the second switch unit 22, the third switch unit 31, and the fourth switch unit 32 to be turned off.

[0036] Continue to refer Figure 3 The first half-bridge circuit 2 includes: a first capacitor C1, a first switch unit 21 and a second switch unit 22.

[0037] The first end of the first capacitor C1 is connected to the positive electrode of the battery pack 1, the second end of the first capacitor C1 is connected to the first end of the first switch unit 21, the second end of the first switch unit 21 is connected to the first end of the second switch unit 22, and the second end of the second switch unit 22 is grounded GND; the primary coil is connected between the first end of the first capacitor C1 and the second end of the first switch unit 21.

[0038] In the embodiment of the present invention, the first switch unit 21 and the second switch unit 22 include but are not limited to bipolar transistors, field effect transistors or composite transistors.

[0039] Specifically, when the difference in power of the single cells BAT1-BATn in the battery pack 1 is greater than or equal to the threshold, that is, when the power difference between the single cells BAT1-BATn with the largest power and the single cells BAT1-BATn with the smallest power in the battery pack 1 is greater than or equal to the threshold, the control circuit 4 outputs a first control signal to the drive circuit 5, and the drive circuit 5 outputs a conduction signal to the control end of the second switch unit 22, and the second switch unit 22 is turned on, and outputs a cutoff signal to the control end of the first switch unit 21, and the first switch unit 21 is turned off, and the battery pack 1 is controlled to charge the primary coil. After charging for a certain period of time, the drive circuit 5 outputs a cutoff signal to the control end of the second switch unit 22, and the second switch unit 22 is turned off; outputs a conduction signal to the control end of the first switch unit 21, and the first switch unit 21 is turned on, and the control charging circuit is disconnected, and the primary coil generates an induced voltage, and the opposite end of the primary coil is the positive pole, and the same end is the negative pole. The secondary coil of the transformer T1 also generates an induced voltage, and the opposite end is the positive pole, and the same end is the negative pole. The primary coil, the first capacitor C1 and the first switch unit 21 form an LC oscillation circuit, and the electric energy of the primary coil and the first capacitor C1 is transferred to each other. The driving circuit 5 enables the second half-bridge circuit 3 corresponding to the single battery BAT1-BATn with the lowest power to control the secondary coil corresponding to it to charge the single battery BAT1-BATn with the lowest power, and the second half-bridge circuit 3 corresponding to the remaining single batteries BAT1-BATn controls the secondary coil corresponding to it not to charge the remaining single batteries BAT1-BATn.

[0040] When the power difference of the single cells BAT1-BATn in the battery pack 1 is less than the threshold value, that is, when the power difference between the single cell BAT1-BATn with the highest power and the single cell BAT1-BATn with the lowest power in the battery pack 1 is less than the threshold value, the single cell BAT1-BATn with the highest power is determined, and the second half-bridge circuit 3 corresponding to it controls the single cell BAT1-BATn with the highest power to charge the secondary coil, and this secondary coil is the secondary coil corresponding to the above-mentioned second half-bridge circuit 3. And after charging for a certain period of time, the charging circuit is controlled to be disconnected, at this time, the secondary coil generates an induced electromotive force, and the same-name end is the positive pole and the opposite-name end is the negative pole, and the primary coil of the transformer T1 also generates an induced electromotive force, and the same-name end is the positive pole and the opposite-name end is the negative pole. The driving circuit 5 outputs a conduction signal to the control end of the second switch unit 22, and the second switch unit 22 is turned on, and outputs a cut-off signal to the control end of the first switch unit 21, and the first switch unit 21 is turned off, and the primary coil is controlled to charge the battery pack 1, so as to achieve the balance of power of the single cells BAT1-BATn in the battery pack 1. At this time, the driving circuit 5 may also output a cutoff signal to the control end of the second switch unit 22 , the second switch unit 22 is turned off, and the primary coil charges the battery pack 1 through the body diode of the second switch unit 22 .

[0041] Continue to refer Figure 3 The first switch unit 21 includes a first IGBT tube Q1 and a first diode D1; the second switch unit 22 includes a second IGBT tube Q2 and a second diode D2.

[0042] The collector of the first IGBT tube Q1 serves as the first end of the first switch unit 21 , the emitter of the first IGBT tube Q1 serves as the second end of the first switch unit 21 , and the first diode D1 is connected in parallel between the collector of the first IGBT tube Q1 and the emitter of the first IGBT tube Q1 .

[0043] The collector of the second IGBT tube Q2 serves as the first end of the second switch unit 22 , the emitter of the second IGBT tube Q2 serves as the second end of the second switch unit 22 , and the second diode D2 is connected in parallel between the collector of the second IGBT tube Q2 and the emitter of the second IGBT tube Q2 .

[0044] Specifically, the gate of the first IGBT tube Q1 can be used as the control end of the first switch unit 21 , and the gate of the second IGBT tube Q2 can be used as the control end of the second switch unit 22 .

[0045] When the difference in power of the single cells BAT1-BATn in the battery pack 1 is greater than or equal to the threshold value, that is, when the difference in power between the single cells BAT1-BATn with the largest power and the single cells BAT1-BATn with the smallest power in the battery pack 1 is greater than or equal to the threshold value, the control circuit 4 outputs a first control signal to the drive circuit 5, and the drive circuit 5 outputs a conduction signal to the gate of the second IGBT tube Q2, and the second IGBT tube Q2 is turned on, and outputs a cutoff signal to the gate of the first IGBT tube Q1, and the first IGBT tube Q1 is turned off, and controls the battery pack 1 to charge the primary coil. After charging for a certain period of time, the drive circuit 5 outputs a cutoff signal to the gate of the second IGBT tube Q2, and the second IGBT tube Q2 is turned off; outputs a conduction signal to the gate of the first IGBT tube Q1, and the first IGBT tube Q1 is turned on, and controls the charging circuit to be disconnected, and the primary coil generates an induced voltage, and the opposite end of the primary coil is the positive pole, and the same end is the negative pole. The secondary coil of the transformer T1 also generates an induced voltage, and the opposite end is the positive pole, and the same end is the negative pole. The primary coil, the first capacitor C1 and the first IGBT tube Q1 form an LC oscillation circuit, and the electric energy of the primary coil and the first capacitor C1 is transferred to each other. The driving circuit 5 enables the second half-bridge circuit 3 corresponding to the single battery BAT1-BATn with the lowest power to control the secondary coil corresponding to it to charge the single battery BAT1-BATn with the lowest power, and the second half-bridge circuit 3 corresponding to the remaining single batteries BAT1-BATn controls the secondary coil corresponding to it not to charge the remaining single batteries BAT1-BATn.

[0046] When the power difference of the single cells BAT1-BATn in the battery pack 1 is less than the threshold value, that is, when the power difference between the single cell BAT1-BATn with the highest power and the single cell BAT1-BATn with the lowest power in the battery pack 1 is less than the threshold value, the single cell BAT1-BATn with the highest power is determined, and the second half-bridge circuit 3 corresponding to it controls the single cell BAT1-BATn with the highest power to charge the secondary coil, and this secondary coil is the secondary coil corresponding to the above second half-bridge circuit 3. After charging for a certain period of time, the charging circuit is controlled to be disconnected. At this time, the secondary coil generates an induced electromotive force, and the same-name end is the positive pole and the opposite-name end is the negative pole. The primary coil of the transformer T1 also generates an induced electromotive force, and the same-name end is the positive pole and the opposite-name end is the negative pole. The driving circuit 5 outputs a conduction signal to the gate of the second IGBT tube Q2, and the second IGBT tube Q2 is turned on. The driving circuit 5 outputs a cutoff signal to the gate of the first IGBT tube Q1, and the first IGBT tube Q1 is turned off, and the primary coil is controlled to charge the battery pack 1, so as to achieve the battery balance of the single cells BAT1-BATn in the battery pack 1. At this time, the driving circuit 5 can also output a cutoff signal to the gate of the second IGBT tube Q2, and the second IGBT tube Q2 is turned off, and the primary coil charges the battery pack 1 through the second diode D2.

[0047] Continue to refer Figure 3 The second half-bridge circuit 3 includes: a second capacitor C2, a third switch unit 31 and a fourth switch unit 32.

[0048] The first end of the second capacitor C2 is connected to the positive electrode of the battery pack 1, the second end of the second capacitor C2 is connected to the first end of the third switch unit 31, the second end of the third switch unit 31 is connected to the first end of the fourth switch unit 32, and the second end of the fourth switch unit 32 is grounded; the secondary coil is connected between the first end of the second capacitor C2 and the second end of the third switch unit 31.

[0049] In the embodiment of the present invention, the third switch unit 31 and the fourth switch unit 32 include but are not limited to bipolar transistors, field effect transistors or composite transistors.

[0050] Specifically, when the difference in power of the single cells BAT1-BATn in the battery pack 1 is greater than or equal to the threshold, that is, when the power difference between the single cells BAT1-BATn with the largest power and the single cells BAT1-BATn with the smallest power in the battery pack 1 is greater than or equal to the threshold, the control circuit 4 outputs a first control signal to the drive circuit 5, and the drive circuit 5 outputs a conduction signal to the control end of the second switch unit 22, and the second switch unit 22 is turned on, and outputs a cutoff signal to the control end of the first switch unit 21, and the first switch unit 21 is turned off, and the battery pack 1 is controlled to charge the primary coil. After charging for a certain period of time, the drive circuit 5 outputs a cutoff signal to the control end of the second switch unit 22, and the second switch unit 22 is turned off; outputs a conduction signal to the control end of the first switch unit 21, and the first switch unit 21 is turned on, and the control charging circuit is disconnected, and the primary coil generates an induced voltage, and the opposite end of the primary coil is the positive pole, and the same end is the negative pole. The secondary coil of the transformer T1 also generates an induced voltage, and the opposite end is the positive pole, and the same end is the negative pole. The third switch unit 31 and the fourth switch unit 32 in the second half-bridge circuit 3 corresponding to the single battery BAT1-BATn with the lowest power are turned off, and the secondary coil corresponding to the second half-bridge circuit 3 charges the single battery BAT1-BATn with the lowest power through the body diode of the fourth switch unit 32. The driving circuit 5 outputs a conduction signal to the control end of the third switch unit 31 in the second half-bridge circuit 3 corresponding to the remaining single batteries BAT1-BATn, and the third switch unit 31 in the second half-bridge circuit 3 corresponding to the remaining single batteries BAT1-BATn is turned on. At this time, the second capacitor C2, the third switch unit 31 and the corresponding secondary coil form an LC oscillation circuit, and the electric energy of the secondary coil and the second capacitor C2 is transferred to each other, so as to prevent the secondary coil from charging the remaining corresponding single batteries BAT1-BATn. With this arrangement, a higher balancing efficiency can be obtained, which can reach up to 95%.

[0051] When the power difference between the single cells BAT1-BATn in the battery pack 1 is less than a threshold value, that is, when the power difference between the single cell BAT1-BATn with the highest power and the single cell BAT1-BATn with the lowest power in the battery pack 1 is less than the threshold value, the single cell BAT1-BATn with the highest power is determined, and the driving circuit 5 outputs a conduction signal to the control end of the fourth switch unit 32 of the second half-bridge circuit 3 corresponding to the single cell BAT1-BATn with the highest power, and controls the single cell BAT1-BATn with the highest power to charge the secondary coil, which is the secondary coil corresponding to the above-mentioned second half-bridge circuit 3. After charging for a certain period of time, the driving circuit 5 outputs a cutoff signal to the control end of the fourth switch unit 32 of the second half-bridge circuit 3 corresponding to the single battery BAT1-BATn with the highest power, and outputs a conduction signal to the control end of the third switch unit 31 of the second half-bridge circuit 3 corresponding to the single battery BAT1-BATn with the highest power, controlling the charging circuit to be disconnected. At this time, the secondary coil generates an induced electromotive force, and the same-name end is the positive pole and the opposite-name end is the negative pole. The primary coil of the transformer T1 also generates an induced electromotive force, and the same-name end is the positive pole and the opposite-name end is the negative pole. The driving circuit 5 outputs a conduction signal to the control end of the second switch unit 22, and the second switch unit 22 is turned on. The driving circuit 5 outputs a cutoff signal to the control end of the first switch unit 21, and the first switch unit 21 is turned off, controlling the primary coil to charge the battery pack 1, and realizing the balance of power of the single batteries BAT1-BATn in the battery pack 1. At this time, the driving circuit 5 can also output a cutoff signal to the control end of the second switch unit 22, and the second switch unit 22 is turned off, and the primary coil charges the battery pack 1 through the body diode of the second switch unit 22.

[0052] Continue to refer Figure 3 The third switch unit 31 includes a third IGBT tube Q3 and a third diode D3; the fourth switch unit 32 includes a fourth IGBT tube Q4 and a fourth diode D4.

[0053] The collector of the third IGBT tube Q3 serves as the first end of the third switch unit 31 , the emitter of the third IGBT tube Q3 serves as the second end of the third switch unit 31 , and the third diode D3 is connected in parallel between the collector of the third IGBT tube Q3 and the emitter of the third IGBT tube Q3 .

[0054] The collector of the fourth IGBT tube Q4 serves as the first end of the fourth switch unit 32 , the emitter of the fourth IGBT tube Q4 serves as the second end of the fourth switch unit 32 , and the fourth diode D4 is connected in parallel between the collector of the fourth IGBT tube Q4 and the emitter of the fourth IGBT tube Q4 .

[0055] Specifically, the gate of the third IGBT tube Q3 can be used as the control end of the third switch unit 31 , and the gate of the fourth IGBT tube Q4 can be used as the control end of the fourth switch unit 32 .

[0056] When the difference in power of the single cells BAT1-BATn in the battery pack 1 is greater than or equal to the threshold value, that is, when the difference in power between the single cells BAT1-BATn with the largest power and the single cells BAT1-BATn with the smallest power in the battery pack 1 is greater than or equal to the threshold value, the control circuit 4 outputs a first control signal to the drive circuit 5, and the drive circuit 5 outputs a conduction signal to the gate of the second IGBT tube Q2, and the second IGBT tube Q2 is turned on, and outputs a cutoff signal to the gate of the first IGBT tube Q1, and the first IGBT tube Q1 is turned off, and controls the battery pack 1 to charge the primary coil. After charging for a certain period of time, the drive circuit 5 outputs a cutoff signal to the gate of the second IGBT tube Q2, and the second IGBT tube Q2 is turned off; outputs a conduction signal to the gate of the first IGBT tube Q1, and the first IGBT tube Q1 is turned on, and controls the charging circuit to be disconnected, and the primary coil generates an induced voltage, and the opposite end of the primary coil is the positive pole, and the same end is the negative pole. The secondary coil of the transformer T1 also generates an induced voltage, and the opposite end is the positive pole, and the same end is the negative pole. The third IGBT tube Q3 and the fourth IGBT tube Q4 in the second half-bridge circuit 3 corresponding to the single battery BAT1-BATn with the lowest power are turned off, and the secondary coil corresponding to the second half-bridge circuit 3 charges the single battery BAT1-BATn with the lowest power through the fourth diode D4. The driving circuit 5 outputs a conduction signal to the gate of the third IGBT tube Q3 in the second half-bridge circuit 3 corresponding to the remaining single batteries BAT1-BATn, and the third IGBT tube Q3 in the second half-bridge circuit 3 corresponding to the remaining single batteries BAT1-BATn is turned on. At this time, the second capacitor C2, the third IGBT tube Q3 and the corresponding secondary coil form an LC oscillation circuit, and the electric energy of the secondary coil and the second capacitor C2 is transferred to each other, so as to prevent the secondary coil from charging the remaining corresponding single batteries BAT1-BATn. In this way, a higher balancing efficiency can be obtained, which can reach up to 95%.

[0057] When the power difference of the single cells BAT1-BATn in the battery pack 1 is less than a threshold value, that is, when the power difference between the single cell BAT1-BATn with the highest power and the single cell BAT1-BATn with the lowest power in the battery pack 1 is less than the threshold value, the single cell BAT1-BATn with the highest power is determined, and the driving circuit 5 outputs a conduction signal to the gate of the fourth IGBT tube Q4 of the second half-bridge circuit 3 corresponding to the single cell BAT1-BATn with the highest power, and controls the single cell BAT1-BATn with the highest power to charge the secondary coil, which is the secondary coil corresponding to the above-mentioned second half-bridge circuit 3. After charging for a certain period of time, the driving circuit 5 outputs a cut-off signal to the gate of the fourth IGBT tube Q4 of the second half-bridge circuit 3 corresponding to the single battery BAT1-BATn with the highest power, and outputs a conduction signal to the gate of the third IGBT tube Q3 of the second half-bridge circuit 3 corresponding to the single battery BAT1-BATn with the highest power, controlling the charging circuit to be disconnected. At this time, the secondary coil generates an induced electromotive force, and the same-name end is the positive pole and the opposite-name end is the negative pole. The primary coil of the transformer T1 also generates an induced electromotive force, and the same-name end is the positive pole and the opposite-name end is the negative pole. The driving circuit 5 outputs a conduction signal to the gate of the second IGBT tube Q2, and the second IGBT tube Q2 is turned on. The driving circuit 5 outputs a cut-off signal to the gate of the first IGBT tube Q1, and the first IGBT tube Q1 is turned off, controlling the primary coil to charge the battery pack 1, and realizing the balance of power of the single batteries BAT1-BATn in the battery pack 1. At this time, the driving circuit 5 may also output a cutoff signal to the gate of the second IGBT tube Q2, the second IGBT tube Q2 is turned off, and the primary coil charges the battery pack 1 through the second diode D2.

[0058] Continue to refer Figure 3 The transformer T1 includes multiple secondary coils, and the multiple secondary coils share the same magnetic core.

[0059] Specifically, the transformer T1 may include multiple secondary coils, and multiple stimulation coils are wound on the same magnetic core, and the transformer T1 may be a high-frequency magnetic integrated transformer. This arrangement can achieve a significant reduction in volume and weight while ensuring the same power transmission capacity, and the magnetic integrated transformer has higher energy efficiency, smaller current loss, and smaller magnetic loss.

[0060] Continue to refer Figure 3 , the winding direction of the primary coil of transformer T1 and the secondary coil of transformer T1 are opposite.

[0061] Specifically, the winding directions of the primary coil of the transformer T1 and the secondary coil of the transformer T1 can be set to be opposite, that is, the same-name ends of the primary coil and the secondary coil of the transformer T1 are not at the same end. This setting can minimize the complexity and cost of the battery balancing circuit.

[0062] An embodiment of the utility model provides an energy storage system, which includes multiple battery packs, and the battery packs include multiple single cells connected in series; the battery packs can be balanced controlled by the battery balancing circuit provided by any of the above embodiments of the utility model, and have the beneficial effects of the battery balancing circuit provided by any of the above embodiments of the utility model.

[0063] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0064] The above specific implementations do not constitute a limitation on the protection scope of the present utility model. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A battery balancing circuit, characterized in that: include: A battery pack, comprising a plurality of single cells connected in series; A first half-bridge circuit; A plurality of second half-bridge circuits are arranged corresponding to the single cells one by one, and the second half-bridge circuits are connected in parallel with the corresponding single cells; A transformer, the transformer comprising a primary coil and a secondary coil arranged in one-to-one correspondence with the second half-bridge circuit, the primary coil is connected to the first half-bridge circuit, and the secondary coil is connected to the second half-bridge circuit.

2. The battery equalization circuit according to claim 1, characterized in that: Also includes: Control circuit and drive circuit; The control circuit is connected to the driving circuit and is used to control the driving circuit to output an on signal or an off signal; The driving circuit is connected to the first half-bridge circuit and the second half-bridge circuit, and is used to output the on-signal or the off-signal to the first half-bridge circuit and the second half-bridge circuit.

3. The battery equalization circuit according to claim 2, characterized in that: The first half-bridge circuit includes a first switch unit and a second switch unit; the second half-bridge circuit includes a third switch unit and a fourth switch unit; The driving circuit is connected to the control end of the first switch unit, the control end of the second switch unit, the control end of the third switch unit, and the control end of the fourth switch unit, and is used to output the on-signal or the off-signal to the control end of the first switch unit, the control end of the second switch unit, the control end of the third switch unit, and the control end of the fourth switch unit.

4. The battery equalization circuit according to claim 1, characterized in that: The first half-bridge circuit includes: a first capacitor, a first switch unit and a second switch unit; The first end of the first capacitor is connected to the positive electrode of the battery pack, the second end of the first capacitor is connected to the first end of the first switch unit, the second end of the first switch unit is connected to the first end of the second switch unit, and the second end of the second switch unit is grounded; the primary coil is connected between the first end of the first capacitor and the second end of the first switch unit.

5. The battery equalization circuit according to claim 4, characterized in that: The first switch unit includes a first IGBT tube and a first diode; the second switch unit includes a second IGBT tube and a second diode; The collector of the first IGBT tube serves as the first end of the first switch unit, the emitter of the first IGBT tube serves as the second end of the first switch unit, and the first diode is connected in parallel between the collector of the first IGBT tube and the emitter of the first IGBT tube; The collector of the second IGBT tube serves as the first end of the second switch unit, the emitter of the second IGBT tube serves as the second end of the second switch unit, and the second diode is connected in parallel between the collector of the second IGBT tube and the emitter of the second IGBT tube.

6. The battery equalization circuit according to claim 1, characterized in that: The second half-bridge circuit includes: a second capacitor, a third switch unit and a fourth switch unit; The first end of the second capacitor is connected to the positive electrode of the battery pack, the second end of the second capacitor is connected to the first end of the third switch unit, the second end of the third switch unit is connected to the first end of the fourth switch unit, and the second end of the fourth switch unit is grounded; the secondary coil is connected between the first end of the second capacitor and the second end of the third switch unit.

7. The battery equalization circuit according to claim 6, characterized in that: The third switch unit includes a third IGBT tube and a third diode; the fourth switch unit includes a fourth IGBT tube and a fourth diode; The collector of the third IGBT tube serves as the first end of the third switch unit, the emitter of the third IGBT tube serves as the second end of the third switch unit, and the third diode is connected in parallel between the collector of the third IGBT tube and the emitter of the third IGBT tube; The collector of the fourth IGBT tube serves as the first end of the fourth switch unit, the emitter of the fourth IGBT tube serves as the second end of the fourth switch unit, and the fourth diode is connected in parallel between the collector of the fourth IGBT tube and the emitter of the fourth IGBT tube.

8. The battery equalization circuit according to claim 1, characterized in that: The transformer includes a plurality of secondary coils, and the plurality of secondary coils share a same magnetic core.

9. The battery equalization circuit according to claim 1, characterized in that: The winding directions of the primary coil of the transformer and the secondary coil of the transformer are opposite.

10. An energy storage system, comprising a plurality of battery packs, wherein the battery packs comprise a plurality of single cells connected in series; characterized in that: The battery pack adopts the battery balancing circuit described in any one of claims 1-9 to perform balancing control.

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