Battery equalization circuit and battery pack

Abstract

The embodiment of the utility model provides a battery equalization circuit and a battery pack, and the circuit comprises a switching circuit, a drive circuit connected with the switching circuit, and a first battery. The driving circuit is used for sending a first level signal to the switching circuit under the condition that a battery to be equalized exists; the switching circuit is used for controlling the working state of a target field effect transistor in the switching circuit according to the first level signal, and the target field effect transistor is a field effect transistor connected with the battery to be equalized; and the first battery is used for balancing the energy of the battery to be balanced under the condition that the working state of the target field effect transistor is on.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circuit, in particular to a battery equalization circuit and a battery pack. BACKGROUND

[0002] At present, in the energy storage system, the number of single system battery cells is from several hundred to several thousand, and it is difficult to avoid the self-discharge of single battery cells due to individual differences, which leads to the decline of system consistency. In order to meet the use of maximum capacity and long service life, the consistency between batteries can be improved through equalization strategy. At present, the main scheme used is mainly passive equalization scheme, and active equalization scheme is rarely used. At present, the passive equalization scheme cannot be applied to large capacity battery cells due to heat dissipation and strategy problems, and the active equalization scheme on the market cannot be applied on a large scale due to poor reliability of switching circuit and high cost of matrix switch scheme (for example, mechanical switch, PhotoMOS scheme).

[0003] In view of the problem that the active equalization scheme in the prior art often adopts a complex matrix switch design, resulting in high material cost, no effective solution has been proposed so far.

[0004] Therefore, it is necessary to improve the related technology to overcome the defects in the related technology. CONTENT OF THE INVENTION

[0005] The embodiments of the present application provide a battery equalization circuit and a battery pack to at least solve the problem that the active equalization scheme in the prior art often adopts a complex matrix switch design, resulting in high material cost.

[0006] According to one embodiment of the present application, a battery equalization circuit method is provided, comprising: a switching circuit, a driving circuit connected with the switching circuit and a first battery; the driving circuit is used for sending a first level signal to the switching circuit in the presence of a battery to be equalized; the switching circuit is used for controlling the working state of a target field effect transistor in the switching circuit according to the first level signal, wherein the target field effect transistor is a field effect transistor connected with the battery to be equalized; and the first battery is used for equalizing the energy of the battery to be equalized in the case that the working state of the target field effect transistor is on.

[0007] In one exemplary embodiment, the battery equalization circuit further comprises a detection circuit connected with the switching circuit and the driving circuit, wherein the detection circuit is used for detecting the health state of the field effect transistor in the switching circuit and outputting a second level signal according to the health state; and the driving circuit is used for determining whether to start the active equalization function of the battery equalization circuit according to the second level signal.

[0008] In an example embodiment, the detection circuit is configured to receive the third level signal sent by the driving circuit, output a fourth level signal when the health status of the field effect transistor is in the abnormal state, and output a fifth level signal when the health status of the field effect transistor is in the normal state, wherein the fourth level signal and the fifth level signal are signals of different level types, and the second level signal comprises the fourth level signal and the fifth level signal.

[0009] In an example embodiment, the driving circuit is configured to turn on the active balancing function of the battery balancing circuit when the second level signal is a first level type of signal, and turn off the active balancing function of the battery balancing circuit when the second level signal is a second level type of signal.

[0010] In an example embodiment, the detection circuit comprises a first detection circuit and a second detection circuit, wherein the first detection circuit is configured to detect the health status of a field effect transistor in a first set of field effect transistors in the switching circuit, and the field effect transistor in the first set of field effect transistors is a field effect transistor connected to the negative electrode of the first battery; and the second detection circuit is configured to detect the health status of a field effect transistor in a second set of field effect transistors in the switching circuit, and the field effect transistor in the second set of field effect transistors is a field effect transistor connected to the positive electrode of the first battery.

[0011] In an example embodiment, the first detection circuit comprises a first diode, a first triode, a first resistor, a second diode, and a second triode, wherein the anode of the first diode is connected to a first enable pin of the driving circuit, the cathode of the first diode is connected to the ground and connected to the base of the first triode; the collector of the first triode is connected to the positive electrode of the battery module, and the emitter of the first triode is connected to one end of the first resistor; the other end of the first resistor is connected to the anode of the second diode; the cathode of the second diode is connected to the negative electrode of the first battery and connected to the base of the second triode; the collector of the second triode is connected to a reference voltage, the emitter of the second triode is connected to a first diagnosis pin of the driving circuit, and the emitter of the second triode is configured to output the second level signal.

[0012] In one example embodiment, the second detection circuit includes a third diode, a third transistor, a second resistor, a fourth diode, and a fourth transistor, wherein the anode of the third diode is connected to the second enable pin of the driving circuit, the cathode of the third diode is connected to the ground, and is connected to the base of the third transistor; the emitter of the third transistor is connected to the negative electrode of the battery module, the collector of the third transistor is connected to one end of the second resistor; the other end of the second resistor is connected to the cathode of the fourth diode, and is connected to the base of the fourth transistor; the anode of the third diode is connected to the positive electrode of the first battery; the collector of the fourth transistor is connected to a reference voltage, the emitter of the fourth transistor is connected to the second diagnosis pin of the driving circuit, and the emitter of the fourth transistor is used to output the second level signal.

[0013] In one example embodiment, the switch circuit includes a sub-switch circuit corresponding to each second battery, wherein the battery module includes a plurality of second batteries, and each sub-switch circuit includes a first sub-switch circuit and a second sub-switch circuit, wherein the first sub-switch circuit is connected to the negative electrode of the second battery corresponding to each sub-switch circuit, and is connected to the negative electrode of the first battery; the second sub-switch circuit is connected to the positive electrode of the second battery corresponding to each sub-switch circuit, and is connected to the positive electrode of the first battery.

[0014] In one example embodiment, the first sub-switch circuit includes a first field effect transistor, a second field effect transistor, and a third resistor, wherein the gate of the first field effect transistor is connected to one end of the third resistor, is connected to the gate of the second field effect transistor, and is connected to the first control pin of the driving circuit; the source of the first field effect transistor is connected to the other end of the third resistor, and is connected to the source of the second field effect transistor; the drain of the second field effect transistor is connected to the negative electrode of the first battery; the drain of the second field effect transistor is connected to the negative electrode of the second battery corresponding to each sub-switch circuit; one end of the third resistor is connected to the driving circuit.

[0015] In one example embodiment, the second sub-switching circuit comprises a third field effect transistor, a fourth field effect transistor and a fourth resistor, wherein a gate of the third field effect transistor is connected with one end of the fourth resistor, and connected with a gate of the fourth field effect transistor, and connected with a first control pin of the driving circuit; a source of the third field effect transistor is connected with another end of the fourth resistor, and connected with a source of the fourth field effect transistor; a drain of the fourth field effect transistor is connected with a positive pole of the first battery; the drain of the fourth field effect transistor is connected with a positive pole of a second battery corresponding to each sub-switching circuit; and one end of the fourth resistor is connected with the driving circuit.

[0016] According to one embodiment of the present application, a battery pack is also provided, comprising the battery equalization circuit of any one of the above claims, and a battery module connected with the battery equalization circuit.

[0017] By the battery equalization circuit of the present application, a switching circuit, a driving circuit connected with the switching circuit and a first battery; the driving circuit is used to send a first level signal to the switching circuit in the presence of a battery to be equalized; the switching circuit is used to control the working state of a target field effect transistor in the switching circuit according to the first level signal, wherein the target field effect transistor is a field effect transistor connected with the battery to be equalized; and the first battery is used to equalize the energy of the battery to be equalized in the case that the working state of the target field effect transistor is on. In the embodiment of the present application, the switching circuit in the battery equalization circuit uses the NMOS scheme, which greatly reduces the material cost compared with the traditional mechanical switch and PhotoMOS scheme, and thus can solve the problem of high material cost. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and serve to explain the principles of the present application together with the description.

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0020] Figure 1 is a circuit diagram of a battery equalization circuit according to an embodiment of the present application (I);

[0021] Figure 2 is a circuit diagram of a battery equalization circuit according to an embodiment of the present application (II);

[0022] Figure 3 is a circuit diagram of a switch circuit according to an embodiment of the present application (I);

[0023] Figure 4 is a circuit diagram of a switch circuit according to an embodiment of the present application (II);

[0024] Figure 5 is a circuit diagram of a battery pack according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] Hereinafter, the embodiments of the present application will be described in detail with reference to the accompanying drawings and in conjunction with embodiments.

[0026] It should be noted that the terms "first", "second" and the like in the description and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence.

[0027] In the present embodiment, a battery equalization circuit is provided, Figure 1 is a circuit diagram of a battery equalization circuit according to an embodiment of the present application, as Figure 1 shown, the circuit comprises the following:

[0028] a switch circuit 12, a driving circuit 14 and a first battery 16 connected to the switch circuit 12, wherein

[0029] the driving circuit 14, for sending a first level signal to the switch circuit 12 in the presence of a battery to be equalized;

[0030] It should be noted that the above driving circuit is mainly composed of a driving chip. The driving circuit receives instructions from the battery management system (BMS) or its internal control logic, determines which is the SOC overhigh or overlow battery to be equalized according to the state information (such as voltage, current and temperature, etc.) of each battery to be equalized in the battery module 12, and needs to be equalized. Then, the driving circuit 14 sends a first level signal (for example, a high level signal or a low level signal) to the switch circuit 12, indicating that it controls a specific target field effect transistor to be turned on, so as to realize the transfer of energy.

[0031] As Figure 2 shown, the driving circuit can be understood as Figure 2 M5 in

[0032] the switch circuit 12, for controlling the working state of the target field effect transistor in the switch circuit 12 according to the first level signal, wherein the target field effect transistor is a field effect transistor connected to the battery to be equalized;

[0033] It should be noted that the switch circuit is composed of a plurality of field effect transistors (for example, NMOS tubes) for controlling the connection between the first battery and the battery to be balanced. In the active balancing process, by controlling the on or off of a specific field effect transistor, energy transfer between battery units can be achieved.

[0034] As shown in Figure 2 , the switch circuit can be understood as Figure 2 M2 in the figure, and the field effect transistor can be understood as Figure 2 NMOS tube in the figure.

[0035] The first battery 16 is configured to balance the energy of the battery to be balanced when the target field effect transistor is in the on state.

[0036] In the circuit, the first battery 16 plays a role in balancing the battery energy. When a battery to be balanced needs to be discharged to reduce its SOC, the first battery 16 can absorb the excess electrical energy; on the contrary, when a battery to be balanced needs to be charged to increase its SOC, the first battery 16 can provide the electrical energy. In this way, the energy exchange between the first battery 16 and the battery to be balanced can dynamically adjust the consistency of each battery unit in the battery module, thereby improving the performance and life of the entire battery pack.

[0037] As shown in Figure 2 , the first battery can be understood as Figure 2 M3 in the figure.

[0038] According to the state of the battery in the battery module M1, the driving module M5 selects the switch module M2 to specify the switch to be on, realizing the charging or discharging function; taking the charging and discharging of the battery V2 as an example, the driving module M5 outputs a constant current current through SW1, so that a voltage difference U is formed across R1 and R2 in the switch module M2, so that Q1-Q4 (i.e. the target field effect transistor) is turned on, and bidirectional conduction is realized, that is, when the energy of the first battery is greater than that of the battery to be balanced V2, the battery to be balanced V2 is charged; when the energy of the first battery is less than that of the battery to be balanced V2, the battery to be balanced V2 is discharged to charge the first battery.

[0039] By the above-mentioned circuit, the switch circuit, the driving circuit connected with the switch circuit and the first battery; the driving circuit is used for sending a first level signal to the switch circuit in the presence of a battery to be balanced; the switch circuit is used for controlling the working state of a target field effect transistor in the switch circuit according to the first level signal, wherein the target field effect transistor is a field effect transistor connected with the battery to be balanced; and the first battery is used for balancing the energy of the battery to be balanced in the case that the working state of the target field effect transistor is on. In the embodiment of the application, the switch circuit in the battery balancing circuit uses the NMOS scheme, which greatly reduces the material cost compared with the traditional mechanical switch and PhotoMOS scheme, and thus can solve the problem of high material cost.

[0040] Optionally, the above-mentioned battery balancing circuit further comprises a detection circuit connected with the switch circuit and the driving circuit, wherein the detection circuit is used for detecting the health state of the field effect transistor in the switch circuit and outputting a second level signal according to the health state, wherein the second level signal is a high level signal or a low level signal; and the driving circuit is used for determining whether to start the active balancing function of the battery balancing circuit according to the second level signal.

[0041] In the embodiment of the application, the detection circuit is used for improving the reliability and safety of the circuit, wherein the detection circuit is mainly responsible for monitoring the health state of all field effect transistors in the switch circuit. For example, whether the field effect transistor is short-circuited or open-circuited, whether the threshold voltage is normal, and whether there is a case of excessive temperature or other performance degradation.

[0042] According to the detected health state, the detection circuit outputs a second level signal. This signal can be a high level or a low level. The low level signal indicates that the field effect transistor is healthy or fault-free, and the high level signal may indicate that there is a fault or abnormal state. In the embodiment of the application, the health state is directly conveyed through the level signal, which facilitates the driving circuit or other control system to quickly respond.

[0043] The driving circuit is further used for determining whether to start the active balancing function according to the second level signal from the detection circuit. If the signal output by the detection circuit indicates that all field effect transistors are healthy and abnormal (for example, all signals are low level), the driving circuit allows the battery balancing circuit to work normally and perform balancing operation. Conversely, if the health state of any field effect transistor is detected to be abnormal (for example, there is a high level signal), the driving circuit will prevent the battery balancing circuit from starting or continuing to work, preventing potential circuit failure from causing damage or safety problems to the battery pack.

[0044] As Figure 2As shown, the above detection circuit can be understood as Figure 2 M4 and M6 in FIG. 8.

[0045] In the embodiments of the present application, by introducing the detection circuit and the corresponding control logic in the active balancing circuit, the fault protection and prevention mechanism can be realized. Before starting the balancing operation or during the operation, the circuit automatically checks the health status of the field effect transistor in the switching circuit. Therefore, the use of the faulty field effect transistor in the balancing process can be avoided, thereby reducing the risk of internal short circuit, overheating, etc. of the battery pack, and improving the safety and robustness of the entire system.

[0046] Optionally, the detection circuit is further configured to receive a third level signal sent by the driving circuit; output a fourth level signal in the case that the health status of the field effect transistor is an abnormal state; and output a fifth level signal in the case that the health status of the field effect transistor is a normal state, wherein the fourth level signal and the fifth level signal are signals of different level types, and the second level signal includes the fourth level signal and the fifth level signal.

[0047] Optionally, the driving circuit is further configured to start the active balancing function of the battery balancing circuit in the case that the second level signal is a level signal of a first level type; and stop the active balancing function of the battery balancing circuit in the case that the second level signal is a level signal of a second level type.

[0048] It should be noted that the above level types include the first level type and the second level type, and the level types can be understood as high level and low level.

[0049] The embodiments of the present application limit the output of different level signals according to the health status of the field effect transistor, and the operation performed by the driving circuit according to the input level, specifically:

[0050] The detection circuit receives a third level signal sent by the driving circuit, which is a high level signal. This usually means that the driving circuit is requesting the detection circuit to perform health status detection of the field effect transistor. The third level signal can also be understood as a trigger to activate the detection circuit to start measuring and judging the state of the field effect transistor. For example, when the driving circuit is ready to start the active balancing function, it will send a high level signal to the detection circuit to indicate that it performs the state check of the field effect transistor.

[0051] If the detection circuit finds that the health status of a certain field effect transistor is abnormal in the inspection, it outputs a fourth level signal, which can be a high level signal. The fourth level signal reports the fault condition to the driving circuit. When the driving circuit receives the high level fourth level signal, it determines that the detected field effect transistor has an abnormality, including but not limited to short circuit, open circuit, threshold voltage drift or overheating and other problems. Based on the fourth level signal, the driving circuit will decide not to start or immediately shut down the active balancing function related to the faulty field effect transistor to avoid damage to the battery pack.

[0052] If the detection circuit determines that the health status of the field effect transistor is normal, i.e. no abnormality is found, it outputs a fifth level signal, which can be a low level signal. This signal confirms to the driving circuit that the field effect transistor is in a safe operating state, allowing the driving circuit to continue or start performing the active balancing function.

[0053] In the embodiments of the present application, the detection circuit and the health status reporting mechanism based on the level signal are introduced into the battery balancing circuit, which can effectively improve the self-protection ability of the system and ensure the energy balancing between the battery cells under safe conditions.

[0054] Optionally, the detection circuit includes a first detection circuit and a second detection circuit, wherein the first detection circuit is configured to detect the health status of the field effect transistors in a first field effect transistor set in the switching circuit, and the field effect transistors in the first field effect transistor set are connected to the negative electrode of the first battery; and the second detection circuit is configured to detect the health status of the field effect transistors in a second field effect transistor set in the switching circuit, and the field effect transistors in the second field effect transistor set are connected to the positive electrode of the first battery.

[0055] In the embodiments of the present application, the first detection circuit and the second detection circuit are respectively responsible for monitoring the health status of the field effect transistors connected to the positive and negative electrodes of the first battery. The first detection circuit is configured to inspect all the negative electrode related switching circuit parts to ensure that these field effect transistors do not have abnormal conditions such as short circuit, open circuit, threshold voltage change or overheating. Through this subdivision, the possible fault point can be located more quickly, and the response speed and efficiency of the circuit are improved.

[0056] The second detection circuit is similar to the first detection circuit and is configured to inspect the health status of all field effect transistors in the second field effect transistor set connected to the positive electrode of the second battery.

[0057] The detection circuit is divided into a first detection circuit and a second detection circuit, which can realize dispersed monitoring, that is, each sub-circuit is responsible for a specific group of field effect transistors. Through the embodiments of the present application, the monitoring and diagnosis process is more efficient because the positive and negative field effect transistor health states can be processed in parallel.

[0058] As shown in Figure 2 , the first detection circuit can be understood as Figure 2 M4 in FIG. 4, and the second detection circuit can be understood as Figure 2 M6 in FIG. 4.

[0059] As shown in Figure 3 , the first field effect transistor set can be understood as the NMOS tube in the dashed box in Figure 3 FIG. 4.

[0060] As shown in Figure 4 , the second field effect transistor set can be understood as the NMOS tube in the dashed box in Figure 4 FIG. 4.

[0061] Among them, M5 internally controls EN1 to output a high-level signal, and detects SG1 (that is, a second-level signal). If the SG1 signal is a low-level signal, it is considered that Figure 3 there is no conduction of the NMOS tube in the M2 module in FIG. 4; if the SG1 signal is a high-level signal, it is considered that Figure 3 there is conduction of the NMOS tube in the M2 module in FIG. 4, which prompts a system fault and prohibits the opening of the balancing function.

[0062] M5 internally controls EN2 to output a high-level signal, and detects SG2 (that is, a second-level signal). If the SG2 signal is a low-level signal, it is considered that Figure 4 there is no conduction of the NMOS tube in the M2 module in FIG. 4; if the SG2 signal is a high-level signal, it is considered that Figure 4 there is conduction of the NMOS tube in the M2 module in FIG. 4, which prompts a system fault and prohibits the opening of the balancing function.

[0063] Optionally, this application embodiment provides specific hardware implementation details of the first detection circuit, as follows: The first detection circuit includes: a first diode, a first transistor, a first resistor, a second diode, and a second transistor, wherein the anode of the first diode is connected to the first enable pin (EN1) of the driving circuit, the cathode of the first diode is connected to ground, and the cathode is connected to the base of the first transistor; the collector of the first transistor is connected to the positive terminal of the battery module, and the emitter of the first transistor is connected to one end of the first resistor; the other end of the first resistor is connected to the anode of the second diode; the cathode of the second diode is connected to the negative terminal of the first battery, and the cathode is connected to the base of the second transistor; the collector of the second transistor is connected to a reference voltage, and the emitter of the second transistor is connected to the first diagnostic pin (SG1) of the driving circuit, and the emitter of the second transistor is used to output the second level signal.

[0064] The first detection circuit in this embodiment uses basic electronic components such as diodes, transistors, and resistors to determine whether the field-effect transistor is in normal working condition.

[0065] like Figure 2 As shown, the first diode and the second diode can be understood as Figure 2 In the diagram, the light-emitting diode, the first transistor, and the second transistor can be understood as follows: Figure 2 The two transistors in the device are a first diode and a first transistor forming a switching device, and a second diode and a second transistor forming a switching device, thereby detecting whether the field-effect transistor is in normal working condition.

[0066] The collector of the first transistor is connected to the positive terminal of the battery module (which can be understood as the positive terminal of the battery module, such as...). Figure 2 In the first diode (C3), the emitter is connected through a first resistor. When a high-level signal is received from the first enable pin, the first diode conducts and emits light. The first transistor receives the light signal, and its collector receives the current signal from the battery module, thus enabling the first transistor to conduct. The current signal flows through the first resistor to the second diode. If the field-effect transistor in any of the sub-switching circuits connected to the negative terminal of the first battery fails, a current loop can be formed, allowing the second diode to conduct and emit light. The second transistor receives the light signal and generates a current signal, thus enabling it to conduct. The emitter of the second transistor outputs a high-level signal. If all the field-effect transistors in each sub-switching circuit connected to the negative terminal of the first battery are functioning normally, a current loop cannot be formed, the second diode cannot conduct, and the second transistor cannot conduct. In this case, the emitter of the second transistor outputs a low-level signal.

[0067] One end of the first resistor is connected to the emitter of the first triode, and the other end is connected to the positive electrode of the second diode. The main function of the first resistor is to limit the current, ensuring the stability of the current in the circuit. At the same time, it can also be used for voltage division, making the voltage range that the subsequent circuit can handle more extensive.

[0068] Through the design of the first detection circuit described above, the fault detection of the field effect transistor connected to the positive electrode in the battery module can be realized, providing an important safety protection mechanism for the battery equalization circuit. Through the combination of simple electronic components, complex circuit functions are achieved, ensuring that the system can respond in time when a fault occurs, avoiding damage to the battery pack and failure of the circuit. At the same time, this circuit design has certain universality and flexibility, which can adjust parameters such as the size of the reference voltage according to actual needs, to adapt to different types of field effect transistors and battery packs.

[0069] Optionally, the second detection circuit is implemented by the following hardware: a third diode, a third triode, a second resistor, a fourth diode, and a fourth triode. The positive electrode of the third diode is connected to the second enable pin (EN2) of the drive circuit, the negative electrode of the third diode is connected to the ground, and the base of the third triode is connected to the negative electrode of the third diode. The emitter of the third triode is connected to the negative electrode of the battery module, and the collector of the third triode is connected to one end of the second resistor. The other end of the second resistor is connected to the negative electrode of the fourth diode and the base of the fourth triode. The positive electrode of the third diode is connected to the positive electrode of the first battery. The collector of the fourth triode is connected to a reference voltage, the emitter of the fourth triode is connected to the second diagnostic pin (SG2) of the drive circuit, and the emitter of the fourth triode is used to output the second level signal.

[0070] The second detection circuit uses basic electronic components such as diodes, triodes, and resistors to determine whether the field effect transistor is in a normal working state.

[0071] The emitter of the third triode is connected to the other end of the battery module (which can be understood as the negative electrode of the battery module, such as C0 in Figure 2 The collector is connected through the second resistor.

[0072] As shown in Figure 2As shown, when a high-level signal sent by the second enable pin is received, the third diode is turned on and emits light, the third transistor receives the light signal, and the collector of the third transistor receives the current signal of the battery module, so that the third transistor is turned on, and the current signal flows to the fourth diode through the second resistor. When the field effect transistor in any sub-switching circuit connected to the positive pole of the first battery fails, a current loop can be formed, the fourth diode can be turned on and emit light, and the fourth transistor generates a current signal after receiving the light signal, that is, the fourth transistor is turned on, and the emitter of the fourth transistor outputs a high-level signal. When the field effect transistor in each sub-switching circuit connected to the positive pole of the first battery is normal, a current loop cannot be formed, the fourth diode cannot be turned on, and the fourth transistor cannot be turned on. At this time, the emitter of the fourth transistor outputs a low-level signal.

[0073] One end of the second resistor is connected to the collector of the third transistor, and the other end is connected to the negative pole of the fourth diode. The second resistor is used for current limiting and voltage dividing, and is used to ensure the stability of voltage and current in the circuit.

[0074] Optionally, the switching circuit is implemented as follows: each sub-switching circuit corresponding to a second battery, wherein the battery module includes: a plurality of second batteries, and each sub-switching circuit includes: a first sub-switching circuit and a second sub-switching circuit, wherein the first sub-switching circuit is connected to the negative pole of the second battery corresponding to the each sub-switching circuit and connected to the negative pole of the first battery; and the second sub-switching circuit is connected to the positive pole of the second battery corresponding to the each sub-switching circuit and connected to the positive pole of the first battery.

[0075] The embodiment of the present application defines the construction of each sub-switching circuit corresponding to a second battery to realize active balancing between battery units in the battery module. The switching circuit is designed based on NMOS devices, wherein the first sub-switching circuit is connected to the negative pole of the second battery corresponding to the each sub-switching circuit and connected to the negative pole of the first battery. The second sub-switching circuit is connected to the positive pole of the second battery corresponding to the each sub-switching circuit and connected to the positive pole of the first battery. In the active balancing process, if the voltage of the second battery is higher than that of the first battery, the NMOS in the first sub-switching circuit and the second sub-switching circuit will be driven to be turned on, allowing current to flow from the high-voltage battery to the low-voltage battery, thereby realizing discharging balancing;

[0076] If the voltage of the second battery is lower than that of the first battery, the NMOS in the first sub-switching circuit and the second sub-switching circuit will be driven to be turned on, allowing current to flow from the high-voltage battery to the low-voltage battery, thereby realizing charging balancing.

[0077] Since each second battery has a corresponding first sub-switching circuit and second sub-switching circuit, the energy exchange between any two batteries in the battery module can be flexibly controlled, providing an efficient and scalable battery equalization solution.

[0078] Optionally, the first sub-switching circuit comprises a first field effect transistor, a second field effect transistor and a third resistor, wherein the gate of the first field effect transistor is connected with one end of the third resistor, the gate of the second field effect transistor and the first control pin of the driving circuit; the source of the first field effect transistor is connected with the other end of the third resistor and the source of the second field effect transistor; the drain of the second field effect transistor is connected with the negative electrode of the first battery; the drain of the second field effect transistor is connected with the negative electrode of the second battery corresponding to each sub-switching circuit; and one end of the third resistor is connected with the driving circuit.

[0079] The implementation of the first sub-switching circuit mainly depends on two field effect transistors and a resistor, wherein the gates of the first field effect transistor and the second field effect transistor are connected with the first control pin of the driving circuit, so that the first field effect transistor and the second field effect transistor are affected by the same control signal from the driving circuit.

[0080] The gate of the first field effect transistor and the source of the second field effect transistor are connected through the third resistor and connected with the first control pin of the driving circuit. That is, the driving circuit controls the two transistors simultaneously through the control signal to realize the fast switching of the circuit.

[0081] The drain of the second field effect transistor is connected with the negative electrode of the corresponding second battery. This connection allows the current to flow bidirectionally between the two batteries. When the second field effect transistor is turned on, if the voltage of the second battery is higher than that of the first battery, the current will flow from the negative electrode of the second battery to the negative electrode of the first battery, realizing discharging equalization; if the voltage of the first battery is higher than that of the second battery, the current will flow in the opposite direction, realizing charging equalization.

[0082] As shown in Figure 2 , the third resistor can be understood as R1 in Figure 2 .

[0083] Optionally, the second sub-switching circuit comprises a third field effect transistor, a fourth field effect transistor and a fourth resistor, wherein the gate of the third field effect transistor is connected with one end of the fourth resistor, and with the gate of the fourth field effect transistor, and with the first control pin of the driving circuit; the source of the third field effect transistor is connected with the other end of the fourth resistor, and with the source of the fourth field effect transistor; the drain of the fourth field effect transistor is connected with the positive pole of the first battery; the drain of the fourth field effect transistor is connected with the positive pole of the second battery corresponding to each sub-switching circuit; and one end of the fourth resistor is connected with the driving circuit.

[0084] The gate of the third field effect transistor and the source of the fourth field effect transistor are connected together through the fourth resistor, and are connected with the first control pin of the driving circuit, sharing the same control signal.

[0085] The drain of the fourth field effect transistor is connected with the positive pole of the first battery, and is also connected with the positive pole of the second battery, thereby allowing the current to flow bidirectionally between the first battery and the second battery. When the fourth field effect transistor is turned on, if the voltage of the first battery is higher than that of the second battery, the current will flow from the positive pole of the first battery to the positive pole of the second battery, realizing charge equalization; otherwise, the current will flow in the opposite direction, realizing discharge equalization.

[0086] As shown in Figure 2 , the third resistor can be understood as Figure 2 R2 in the formula.

[0087] According to one embodiment of the present application, a battery pack is also provided, Figure 5 is a circuit diagram of the battery pack according to the embodiment of the present application, as shown in Figure 5 , the circuit comprises the following:

[0088] The above-mentioned battery equalization circuit and the battery module 52 connected with the battery equalization circuit, wherein the battery module 52 comprises a plurality of second batteries.

[0089] It should be noted that the battery module can also be understood as a battery pack, which is composed of a plurality of second batteries. Each second battery can be understood as a battery unit in the battery pack, and these batteries can have different state of charge (SOC) and health status, which is a problem that the battery equalization circuit needs to solve.

[0090] As shown in Figure 2 , the battery module can be understood as Figure 2 M1 in the formula, and the second battery can be understood as Figure 2 V1, V2…Vn in the formula, and the above-mentioned battery to be equalized is any battery to be equalized in the battery module.

[0091] The specific examples in the present embodiments can refer to the examples described in the above embodiments and exemplary embodiments, which will not be repeated here.

[0092] Obviously, those skilled in the art should understand that the modules or steps of the present application described above can be realized by general computing devices, which can be centralized on a single computing device or distributed on a network composed of multiple computing devices, which can be realized by program codes executable by the computing devices, so that they can be stored in storage devices and executed by the computing devices, and in some cases, the steps shown or described can be executed in different order, or they can be respectively manufactured into individual integrated circuit modules, or multiple modules or steps among them can be manufactured into a single integrated circuit module to realize. Thus, the present application is not limited to any specific combination of hardware and software.

[0093] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. within the principles of the present application shall be included in the protection scope of the present application.

Claims

1. A battery equalization circuit, characterized by, The battery equalization circuit comprises a switch circuit, a driving circuit connected with the switch circuit, and a first battery, wherein the driving circuit is configured to send a first level signal to the switch circuit when there is a battery to be equalized. The switch circuit is configured to control a working state of a target field effect transistor in the switch circuit according to the first level signal, wherein the target field effect transistor is a field effect transistor connected with the battery to be equalized. The first battery is configured to equalize energy of the battery to be equalized when the working state of the target field effect transistor is turned on. The battery equalization circuit further comprises a detection circuit connected with the switch circuit and the driving circuit, wherein the detection circuit is configured to detect a health state of a field effect transistor in the switch circuit and output a second level signal according to the health state.

2. The circuit of claim 1, wherein, The driving circuit is configured to determine whether to start an active equalization function of the battery equalization circuit according to the second level signal. The detection circuit is configured to receive a third level signal sent by the driving circuit.

3. The circuit of claim 2, wherein, When the health state of the field effect transistor is an abnormal state, a fourth level signal is outputted. When the health state of the field effect transistor is a normal state, a fifth level signal is outputted, wherein the fourth level signal and the fifth level signal are signals of different level types, and the second level signal comprises the fourth level signal and the fifth level signal. The driving circuit is configured to start the active equalization function of the battery equalization circuit when the second level signal is a first level type of signal. The driving circuit is configured to stop the active equalization function of the battery equalization circuit when the second level signal is a second level type of signal.

4. The circuit of claim 2, wherein, The detection circuit comprises a first detection circuit and a second detection circuit, wherein The first detection circuit is configured to detect a health state of a field effect transistor in a first field effect transistor set in the switch circuit, wherein the field effect transistor in the first field effect transistor set is a field effect transistor connected with a negative electrode of the first battery. The second detection circuit is configured to detect a health state of a field effect transistor in a second field effect transistor set in the switch circuit, wherein the field effect transistor in the second field effect transistor set is a field effect transistor connected with a positive electrode of the first battery.

5. The circuit of claim 2, wherein, The first detection circuit comprises a first diode, a first triode, a first resistor, a second diode, and a second triode, wherein A positive electrode of the first diode is connected with a first enable pin of the driving circuit, a negative electrode of the first diode is connected with a ground, and the negative electrode of the first diode is connected with a base of the first triode. A collector of the first triode is connected with a positive electrode of a battery module, and an emitter of the first triode is connected with one end of the first resistor. The other end of the first resistor is connected with a positive electrode of the second diode.

6. The circuit of claim 5, wherein, A negative electrode of the second diode is connected with a negative electrode of the first battery, and the negative electrode of the second diode is connected with a base of the second triode. ​ ​ ​ ​ ​ The collector of the second transistor is connected with a reference voltage, the emitter of the second transistor is connected with a first diagnostic pin of the driving circuit, and the emitter of the second transistor is used for outputting the second level signal.

7. The circuit of claim 5, wherein, The second detection circuit comprises: A third diode, a third transistor, a second resistor, a fourth diode and a fourth transistor, wherein, The anode of the third diode is connected with a second enable pin of the driving circuit, the cathode of the third diode is connected with the ground, and the base of the third diode is connected with the third transistor; The emitter of the third transistor is connected with the negative electrode of the battery module, and the collector of the third transistor is connected with one end of the second resistor; The other end of the second resistor is connected with the cathode of the fourth diode, and the base of the fourth transistor is connected with the other end of the second resistor; The anode of the third diode is connected with the positive electrode of the first battery; The collector of the fourth transistor is connected with a reference voltage, the emitter of the fourth transistor is connected with a second diagnostic pin of the driving circuit, and the emitter of the fourth transistor is used for outputting the second level signal.

8. The circuit of claim 1, wherein, The switch circuit comprises: Each sub-switch circuit corresponding to each second battery, wherein each sub-switch circuit comprises: a first sub-switch circuit and a second sub-switch circuit, wherein the battery module comprises: a plurality of second batteries, the first sub-switch circuit is connected with the negative electrode of the second battery corresponding to each sub-switch circuit, and is connected with the negative electrode of the first battery; The second sub-switch circuit is connected with the positive electrode of the second battery corresponding to each sub-switch circuit, and is connected with the positive electrode of the first battery.

9. The circuit of claim 8, wherein, The first sub-switch circuit comprises: a first field effect transistor, a second field effect transistor and a third resistor, wherein the gate of the first field effect transistor is connected with one end of the third resistor, is connected with the gate of the second field effect transistor, and is connected with a first control pin of the driving circuit; The source of the first field effect transistor is connected with the other end of the third resistor, and is connected with the source of the second field effect transistor; The drain of the second field effect transistor is connected with the negative electrode of the first battery; The drain of the second field effect transistor is connected with the negative electrode of the second battery corresponding to each sub-switch circuit; One end of the third resistor is connected with the driving circuit.

10. A battery pack, characterized by, It comprises: The battery equalization circuit according to any one of claims 1 to 9, and a battery module connected with the battery equalization circuit.

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