Battery management circuit and energy storage system

Abstract

The present application provides a battery management circuit and an energy storage system. The battery management circuit comprises a plurality of voltage conversion modules, a plurality of first control modules, and a second control module, wherein each voltage conversion module has a direct current side for connecting to a battery and a bus side for connecting to a bus or an electric device, and the plurality of bus sides are connected in series on the bus; the second control module is configured to acquire electrical parameters and outputting a first control signal; and the first control modules are configured to receive and respond to the first control signal so as to control the voltage conversion modules to adjust electrical parameters of batteries. In the present application, one voltage conversion module is arranged for each battery, and the plurality of voltage conversion modules are connected in series to the bus, so that on one hand, the mutual impact between different batteries can be reduced, thus mitigating the Buckets effect, and on the other hand, the transformation ratio of a voltage conversion circuit can be reduced, thus improving conversion efficiency.

Description

Battery management circuit and energy storage system

[0001] The present application claims priority to the Chinese patent application No. 202410946898.5, filed on July 16, 2024 in the China Patent Office and entitled "Battery management circuit and energy storage system", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application belongs to the technical field of battery management, and in particular relates to a battery management circuit and an energy storage system. BACKGROUND

[0003] With the rapid development of modern electronic devices and electric vehicles, the performance requirements for batteries are also increasing. Multiple batteries can be connected in series or parallel to meet different voltage and capacity requirements.

[0004] The series connection mode is to connect multiple batteries end to end to form a battery cluster, and then connect the battery cluster to the bus through a DC / DC conversion circuit. However, the performance differences and uneven aging rates between multiple batteries often have a serious impact on the performance of the entire battery cluster, which is known as the "barrel effect". The parallel connection mode is to configure an independent DC / DC circuit for each battery, and then connect these circuits in parallel to the bus. However, since the parallel connection mode requires a larger voltage conversion ratio, it also leads to higher DC / DC circuit loss, reducing the efficiency of the system.

[0005] Therefore, how to improve the charge and discharge performance of the battery is a problem that needs to be solved by those skilled in the art at present. TECHNICAL PROBLEM

[0006] The purpose of the present application is to provide a battery management circuit and an energy storage system, which aims to solve the problem of poor charge and discharge performance of the battery in the prior art. TECHNICAL SOLUTION

[0007] The first aspect of the embodiments of the present application proposes a battery management circuit for managing multiple batteries, the battery management circuit comprising:

[0008] a plurality of voltage conversion modules, each of the plurality of voltage conversion modules corresponding to one of the multiple batteries, the voltage conversion module having a direct current side and a bus side, the direct current side being configured to connect to the corresponding battery, and the bus side being configured to connect to a bus, and the bus sides of the plurality of voltage conversion modules being connected in series to the bus;

[0009] a plurality of first control modules, each of the plurality of first control modules corresponding to one of the plurality of voltage conversion modules;

[0010] A second control module is configured to acquire an electrical parameter of each of the plurality of batteries and output a first control signal according to the electrical parameter.

[0011] In some embodiments of the present application, the electrical parameter comprises one or more of voltage, current, temperature, and power.

[0012] In some embodiments of the present application, the first control module comprises:

[0013] A first calculation unit is configured to acquire the electrical parameter of the battery connected to the corresponding voltage conversion module;

[0014] A second calculation unit is configured to receive the first control signal and output a second control signal according to the first control signal;

[0015] An execution unit is configured to receive the second control signal and control the voltage conversion module to adjust the electrical parameter of the corresponding battery according to the second control signal;

[0016] The second control module comprises a management unit configured to acquire the electrical parameter and output a maximum charge signal and a minimum charge signal according to the electrical parameter; and the second calculation unit is configured to output the second control signal according to the maximum charge signal and the minimum charge signal.

[0017] In some embodiments of the present application, the second control module further comprises a logic unit configured to output a bus voltage signal and the number of batteries.

[0018] The second calculation unit is further configured to receive the bus voltage signal and the number of batteries and output the second control signal according to the bus voltage signal, the number of batteries, and the maximum charge signal and the minimum charge signal.

[0019] In some embodiments of the present application, the second control signal comprises a current control signal and a voltage control signal; and the second calculation unit comprises:

[0020] A first sub-calculation unit is configured to acquire the maximum charge signal and the minimum charge signal and output a first sub-control signal according to the maximum charge signal and the minimum charge signal;

[0021] A second sub-calculation unit is configured to receive the bus voltage signal and the number of batteries and output a second sub-control signal according to the bus voltage signal and the number of batteries;

[0022] a first adder configured to obtain and output the current control signal according to the first sub-control signal and the second sub-control signal;

[0023] a second adder configured to obtain and output the voltage control signal according to the first sub-control signal and the second sub-control signal.

[0024] In some embodiments of the present application, the first calculation unit is further configured to output a first reference voltage and a first reference current;

[0025] the first adder is configured to obtain and output the current control signal according to the first sub-control signal, the second sub-control signal and the first reference current;

[0026] and / or, the second adder is configured to obtain and output the voltage control signal according to the first sub-control signal, the second sub-control signal and the first reference voltage.

[0027] In some embodiments of the present application, the second calculation unit further comprises:

[0028] a third adder configured to obtain the maximum charge signal and the minimum charge signal, and to output a first operation signal by performing addition operation on the maximum charge signal and the minimum charge signal;

[0029] a multiplier configured to obtain the first operation signal, and to output a second operation signal by multiplying the first operation signal with a preset coefficient; the first sub-calculation unit is configured to output the first sub-control signal according to the maximum charge signal, the minimum charge signal and the second operation signal.

[0030] In some embodiments of the present application, the second control signal comprises a current control signal and a voltage control signal, and the execution unit comprises:

[0031] a generator configured to output a periodic sawtooth wave;

[0032] a first compensator configured to receive the current control signal and a first current signal of the battery, and to output a first compensation signal according to the current control signal and the first current signal;

[0033] a comparator configured to output a first execution signal according to the sawtooth wave and the first compensation signal, the first execution signal being configured to adjust a current of the voltage conversion unit.

[0034] In some embodiments of the present application, the execution unit further comprises a second compensator configured to receive the voltage control signal and a first voltage signal of the battery, and to output a second compensation signal according to the voltage control signal and the first voltage signal.

[0035] The comparator is configured to output a second execution signal according to the sawtooth wave and the second compensation signal, and the second execution signal is used to adjust the voltage of the voltage conversion unit.

[0036] In some embodiments of the present application, the voltage conversion unit is an isolated topology or a non-isolated topology.

[0037] In some embodiments of the present application, the voltage conversion unit comprises:

[0038] a first inductor connected between the positive pole of the battery and the positive pole of the busbar;

[0039] a first capacitor connected between the positive pole of the battery and the positive pole of the busbar, and connected between the negative pole of the battery and the negative pole of the busbar;

[0040] a first transistor connected in parallel with the first capacitor, and configured to receive a third control signal output by a first control module, so as to adjust the voltage and / or current of the battery.

[0041] In some embodiments of the present application, the first transistor comprises a first sub-transistor and a second sub-transistor, and the first sub-transistor and the second sub-transistor are arranged on two sides of the first inductor.

[0042] In some embodiments of the present application, the voltage conversion unit comprises:

[0043] a first converter connected to the battery;

[0044] a second converter connected to the busbar or the electrical equipment, and magnetically coupled with the first converter;

[0045] The first converter is configured to inverse the first direct current output by the battery into a first alternating current; and the second converter is configured to form a second alternating current according to the first alternating current, and convert the second alternating current into a second direct current to output to the electrical equipment.

[0046] Alternatively, the second converter is configured to inverse the third direct current output by the busbar into a third alternating current, and the first converter is configured to form a fourth alternating current according to the third alternating current, and convert the fourth alternating current into a fourth direct current to output to the battery.

[0047] Secondly, this application also provides an energy storage device, which includes a plurality of batteries and the aforementioned battery management circuit. The battery management circuit is used to adjust the electrical parameters of the batteries, which are charging electrical parameters or discharging electrical parameters.

[0048] Thirdly, this application also provides an energy storage system, which includes a charging module and the aforementioned energy storage device, wherein the charging module is used to charge the energy storage device through the bus.

[0049] Fourthly, this application also provides an electrical system, which includes electrical equipment and the aforementioned energy storage device, wherein the electrical equipment is used to discharge the energy storage device through the bus. Beneficial effects

[0050] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows: The battery management circuit and energy storage system described above are used to manage multiple batteries. The battery management circuit includes multiple voltage conversion modules, multiple first control modules, and a second control module. Each voltage conversion module corresponds to one of the multiple batteries. The voltage conversion module has a DC side and a bus side. The DC side is used to connect to the corresponding battery, and the bus side is used to connect to a bus or electrical equipment. The bus sides of the multiple voltage conversion modules are connected in series on the bus. Each of the multiple first control modules corresponds to one of the multiple voltage conversion modules. The second control module is used to acquire the electrical parameters of the multiple batteries and output a first control signal according to the electrical parameters. The first control module is used to receive and respond to the first control signal to control the voltage conversion module to adjust the electrical parameters of the corresponding battery. In other words, in this application, a voltage conversion module is set for each battery, and multiple voltage conversion modules are connected in series on the bus. On the one hand, this can reduce the mutual influence between different batteries, thereby helping to reduce the bottleneck effect; on the other hand, it can reduce the transformation ratio of the voltage conversion circuit, thereby helping to improve the conversion efficiency. Attached Figure Description

[0051] Figure 1 is a schematic diagram of the circuit structure of the battery management circuit provided in the relevant technology of this application;

[0052] Figure 2 is a schematic diagram of the circuit structure of a battery management circuit provided by another related technology of this application;

[0053] Figure 3 is a schematic diagram of the circuit structure of a battery management circuit provided in an embodiment of this application;

[0054] Figure 4 is a schematic diagram of the framework structure of a battery management circuit provided in an embodiment of this application;

[0055] Figure 5 is a schematic diagram of another frame structure of the battery management circuit provided in an embodiment of this application;

[0056] Figure 6 is a schematic diagram of the circuit structure of a battery management circuit provided in another embodiment of this application;

[0057] Figure 7 is a schematic diagram of the framework structure of a battery management circuit provided in another embodiment of this application;

[0058] Figure 8 is a schematic diagram of the framework structure of a battery management circuit provided in another embodiment of this application;

[0059] Figure 9 is a schematic diagram of the circuit structure of a battery management circuit provided in another embodiment of this application;

[0060] Figure 10 is a schematic diagram of the circuit structure of a battery management circuit provided in another embodiment of this application.

[0061] Specific element symbol explanations: 100-Battery, 200-Voltage conversion module, 210-First converter, 220-Second converter, 300-First control module, 310-First computing unit, 320-Second computing unit, 330-Execution unit, 400-Second control module, 410-Management unit, 420-Logic unit, 500-Bus, Lb-First inductor, Q21-First sub-transistor, Q22-Second sub-transistor, Q11-Third sub-transistor, Q12-Fourth sub-transistor, Ca-First sub-capacitor, Cb-Second sub-capacitor. Embodiments of the present invention

[0062] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0063] It should be noted that when a component is referred to as being "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0064] It should be understood that the terms "length", "width", "upper", "lower", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0065] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0066] It's important to understand that with the rapid development of modern electronic devices and electric vehicles, the performance requirements for batteries are also increasing. Battery clusters typically consist of multiple cells, which can be connected in series or parallel to meet different voltage and capacity requirements. However, performance differences and uneven aging rates between cells often have a significant impact on the overall performance of the battery cluster—the so-called "weakest link" effect.

[0067] In existing battery management circuits, series and parallel connections are two common methods. Series connection involves linking multiple batteries end-to-end to form a battery cluster, which is then connected to the bus via a DC / DC converter. While this method can easily increase the voltage of the battery cluster, changes in the performance of a single battery directly affect the performance of the entire cluster. If a battery experiences performance degradation or malfunction, it can lead to a decline in the performance of the entire battery cluster, and may even cause a safety hazard.

[0068] Specifically, please refer to Figure 1, which shows a schematic diagram of the battery management circuit provided in the related technology. In this circuit, the photovoltaic module charges the batteries in the battery management circuit through a bus, a DC / DC (direct current to direct current) circuit, and a DC bus capacitor. The battery management circuit includes a bidirectional DC / DC circuit, with multiple batteries connected in series and parallel before being connected in series with the DC / DC circuit. For batteries connected in series, differences in energy and internal resistance are inevitable between the batteries, and there will also be differences in capacity. After the battery system has been operating for a long time, these differences will become more pronounced, creating a "weakest link" effect, which will reduce the effective usable capacity of the batteries and shorten their lifespan.

[0069] To address the problems associated with series connection methods, some battery management systems (BMS) employ parallel connection methods. In parallel connection, each battery cell is equipped with an independent DC / DC circuit, and these circuits are then connected in parallel to the bus. This method ensures that each battery cell operates at its optimal performance, thereby improving the overall performance of the battery pack. However, since each battery cell requires an independent DC / DC circuit, this increases the system's complexity and cost. Furthermore, the parallel connection requires a larger transformer ratio, which leads to higher losses in the DC / DC circuits and reduces system efficiency.

[0070] Please refer to Figure 2, which shows a schematic diagram of the battery management circuit provided in the related technology. The difference between the technical solution in Figure 2 and the technical solution in Figure 1 is that multiple bidirectional DC / DC circuits are set up, and each bidirectional DC / DC circuit is connected in series with a corresponding battery, and then connected in parallel to the DC bus capacitor. In this way, multiple batteries are essentially connected in parallel, resulting in a large voltage difference between each battery and the bus voltage. However, the bidirectional DC / DC converter circuit must be matched with the battery characteristics, which leads to a large output voltage and output voltage ratio of the bidirectional DC / DC circuit, thus reducing the conversion efficiency. Therefore, the output power is large, resulting in a higher system cost, and the current sharing control method of the parallel output is also more complex.

[0071] Therefore, this application improves the relevant battery management circuit and energy storage system based on this.

[0072] Please refer to Figures 3 to 5. Figure 3 shows a schematic diagram of the circuit structure of the battery 100 management circuit provided in this embodiment. Figure 4 shows a schematic diagram of the frame structure of the battery 100 management circuit provided in this embodiment. Figure 5 shows another schematic diagram of the frame structure of the battery 100 management circuit provided in this embodiment. This embodiment provides a battery management circuit for managing multiple batteries 100. The battery management circuit includes multiple voltage conversion modules 200, multiple first control modules 300, and a second control module 400. Each voltage conversion module 200 corresponds one-to-one with a battery 100. Each voltage conversion module 200 has a DC side and a bus side. The DC side is used to connect to the corresponding battery 100, and the bus side is used to connect to a bus 500. The bus sides of the multiple voltage conversion modules 200 are connected in series with the bus 500. Each first control module 300 corresponds one-to-one with a voltage conversion module 200. The second control module 400 is used to acquire the electrical parameters of the multiple batteries 100 and output a first control signal based on the electrical parameters. The first control modules 300 receive and respond to the first control signal to control the voltage conversion modules 200 to adjust the electrical parameters of the corresponding batteries 100.

[0073] It should be explained that battery 100 may include multiple cells or only one cell. It can be understood that cells are connected in series and parallel to increase voltage and current to form battery 100, and battery 100 is also connected in series and parallel to increase voltage and current to form battery clusters. Finally, multiple parallel battery clusters form a battery pack. In this application, battery 100 can be understood as a battery cluster, and battery 100 can also be understood as a battery pack. Voltage conversion module 200 is used for DC to DC conversion, i.e., direct current to direct current conversion. Electrical parameters can be voltage, current, etc.

[0074] In current battery management circuits, the batteries 100 are often arranged in a simple parallel or series structure. The current parallel structure reduces conversion efficiency, while the current series structure causes interference between different batteries 100. However, in this application, a voltage conversion module 200 is provided for each battery 100, and multiple voltage conversion modules 200 are connected in series to the bus 500. This reduces the mutual influence between different batteries 100, thus mitigating the "weakest link" effect; it also reduces the transformation ratio of the voltage conversion circuit, thereby improving conversion efficiency.

[0075] In some embodiments, the number of batteries 100 can be one or more. For example, there are a total of 10 batteries 100, which are combined into 9 groups. Each group of batteries 100 is provided with a voltage conversion module 200, and there must be two batteries 100 in one group of batteries 100.

[0076] In some embodiments of this application, electrical parameters include one or more of voltage, current, temperature, and power.

[0077] In some embodiments, please continue to refer to Figure 3. Each series optimizer 1~n includes bidirectional DC / DC conversion circuits (corresponding to voltage conversion modules 200) 1~n and local controllers (corresponding to the first control module 300) 1~n. The positive and negative output voltages of all bidirectional DC / DC conversion circuits are connected in series to form a DC bus 500. The positive input port ① and negative input port ② of each series optimizer are connected in parallel with the positive and negative terminals of their respective batteries 100, respectively. The negative output port ④ of series optimizer 1 is connected to the negative terminal of DC bus 500, and the positive output port ③ is connected to the negative output port ④ of series optimizer 2. The positive output port ③ of series optimizer 2 is connected to the negative output port ④ of series optimizer n after being connected in series with the positive and negative output voltages of multiple optimizers. The positive output port ③ of series optimizer n is connected to the positive terminal of DC bus 500. The input and output voltage ratio of a bidirectional DC / DC converter circuit is relatively small, resulting in lower output power. This allows for a reduction in the rated voltage of the power switching transistor, indirectly improving conversion efficiency, reducing device size, and lowering system cost.

[0078] In this embodiment, ports ② and ④ of the series optimizer are connected together. The local controller detects parameters such as battery voltage, current, power, and temperature. After calculating the state of charge / health (SoC / SoH), which is equivalent to completing the battery management function, it reports its respective SoC / SoH parameters to the central controller (equivalent to the second control module 400) and receives and executes instructions and data issued by the central controller, such as SoCmax / SoCmin, charging / discharging control, output voltage, and number of batteries. After calculation, the local controller generates current and voltage reference signals. During charging and discharging, it adopts closed-loop control of battery current or output voltage, and combines its respective SoC / SoH and output voltage droop coefficient to ultimately achieve battery SoC / SoH balance and output voltage balance.

[0079] The working principle is as follows: When battery 100 is charging, the local controller in each series optimizer receives and executes instructions and data from the central controller, draws power from the DC bus 500, and independently controls the charging of battery 100 in a constant current or voltage-limiting manner using closed-loop control. When battery 100 is discharging, each local controller also receives and executes instructions and data from the central controller, using an independent closed-loop control method to increase its own output voltage. Then, all output voltages are connected in series, end to end, to form the voltage of DC bus 500. In other words, the local controller reports its own SoC / SoH parameters, receives and executes instructions and data from the central controller, and combines current-voltage closed-loop control and droop control to independently control its own charging and discharging current and voltage, ultimately achieving SoC / SoH balance and output voltage balance for each battery. It features two levels of control—central and local controllers—making the control method simple and flexible, and facilitating battery system expansion.

[0080] Centralized and local controllers can be built using discrete electronic components or designed using application-specific integrated circuits (ASICs), such as analog control chips, software-programmable microcontrollers (MCUs), digital signal processors (DSPs), or programmable logic devices (FPGAs / CPLDs). Bidirectional DC / DC converter circuits can be implemented using discrete components or integrated circuits, or integrated into the controller to form a large-scale hybrid integrated circuit. This highly integrated controller design can further reduce the size of the series optimizer device.

[0081] In some embodiments of this application, please refer to Figures 6 and 7. Figure 6 shows a schematic diagram of the circuit structure of the battery 100 management circuit provided in this embodiment, and a schematic diagram of the framework structure of the battery 100 management circuit provided in this embodiment. The first control module 300 of this embodiment includes a first calculation unit 310, a second calculation unit 320, and an execution unit 330. The first calculation unit 310 is used to obtain the electrical parameters of the battery 100 connected to the corresponding voltage conversion module 200, and calculate the electrical parameters accordingly. The second calculation unit 320 is used to receive and output a second control signal according to the first control signal. The execution unit 330 is used to receive and control the voltage conversion module 200 to adjust the electrical parameters of the corresponding battery 100 according to the second control signal. The second control module 400 includes a management unit 410, which is used to obtain the electrical parameters and output a maximum charge signal and a minimum charge signal according to the electrical parameters. The second calculation unit 320 is used to output a second control signal according to the maximum charge signal and the minimum charge signal.

[0082] It should be explained that the first calculation unit 310 can obtain the electrical parameters of the battery 100, such as the input voltage, input current, temperature, input power, etc. when the battery 100 is charging, or the output voltage, output current, temperature, and output power, etc. when it is discharging.

[0083] In some embodiments of this application, please refer to FIG8, which shows a schematic diagram of the framework structure of the battery 100 management circuit provided in this embodiment. The second control module 400 of this embodiment further includes a logic unit 420, which is used to output the bus 500 voltage signal and the number of batteries 100; the second calculation unit 320 is also used to receive the bus 500 voltage signal and the number of batteries 100, and output a second control signal according to the bus 500 voltage signal, the number of batteries 100, and the maximum charge signal and the minimum charge signal.

[0084] In some embodiments of this application, please continue to refer to Figures 6 and 8; the first sub-calculation unit is equivalent to the droop calculation unit U3 in Figure 6, and the second sub-calculation unit is equivalent to the output voltage droop calculation unit U4 in Figure 6. The second control signal in this embodiment includes a current control signal and a voltage control signal; the second calculation unit 320 includes a first sub-calculation unit, a second sub-calculation unit, a first adder, and a second adder; the first sub-calculation unit is used to acquire the maximum charge signal and the minimum charge signal, and output the first sub-control signal according to the maximum charge signal and the minimum charge signal; the second sub-calculation unit is used to receive the bus 500 voltage signal and the number of batteries 100, and output the second sub-control signal according to the bus 500 voltage signal and the number of batteries 100; the first adder is used to acquire and output the current control signal according to the first sub-control signal and the second sub-control signal; the second adder is used to acquire and output the voltage control signal according to the first sub-control signal and the second sub-control signal.

[0085] In some embodiments of this application, please continue to refer to FIG6. The first calculation unit 310 is also used to output a first reference voltage and a first reference current; the first adder is used to acquire and output a current control signal according to the first sub-control signal, the second sub-control signal and the first reference current; and / or, the second adder is used to acquire and output a voltage control signal according to the first sub-control signal, the second sub-control signal and the first reference voltage.

[0086] In some embodiments of this application, please continue to refer to FIG6. The second calculation unit 320 further includes a third adder and a multiplier. The third adder is used to acquire the maximum charge signal and the minimum charge signal, and to perform an addition operation on the maximum charge signal and the minimum charge signal to obtain a first operation signal. The multiplier is used to acquire the first operation signal, and to multiply the first operation signal with a preset coefficient to output a second operation signal. The first sub-calculation unit outputs a first sub-control signal based on the maximum charge signal, the minimum charge signal and the second operation signal.

[0087] In some embodiments of this application, please continue to refer to Figure 6. The sawtooth wave generator in Figure 8 is a generator, the compensation unit U6 is a first compensator, and the comparator is a PWM unit U9. The second control signal in this embodiment includes a current control signal and a voltage control signal. The execution unit 330 includes a generator, a first compensator, and a comparator. The generator is used to output a periodic sawtooth wave. The first compensator is used to receive the current control signal and the first current signal of the battery 100, and output a first compensation signal according to the current control signal and the first current signal. The comparator is used to output a first execution signal according to the sawtooth wave and the first compensation signal. The first execution signal is used to adjust the current of the voltage conversion unit.

[0088] In some embodiments of this application, please continue to refer to FIG6. The compensation unit U7 is a second compensator. The execution unit 330 also includes a second compensator. The second compensator is used to receive the voltage control signal and the first voltage signal of the battery 100, and output a second compensation signal according to the voltage control signal and the first voltage signal. The comparator is used to output a second execution signal according to the sawtooth wave and the second compensation signal. The second execution signal is used to adjust the voltage of the voltage conversion unit.

[0089] In some embodiments of this application, the voltage conversion unit is an isolated topology or a non-isolated topology.

[0090] In some embodiments of this application, please continue to refer to FIG6. The voltage conversion unit includes a first inductor Lb, a first capacitor, and a first transistor. The first inductor Lb is connected between the positive terminal of the battery 100 and the positive terminal of the bus 500. One end of the first capacitor is connected between the positive terminal of the battery 100 and the positive terminal of the bus 500, and the other end is connected between the negative terminal of the battery 100 and the negative terminal of the bus 500. The first transistor is connected in parallel with the first capacitor and is used to receive the third control signal output by the first control module 300 to adjust the voltage and / or current of the battery 100.

[0091] In some embodiments, the voltage conversion unit further includes a second transistor connected in series between the positive terminal of the battery 100 and the positive terminal of the bus 500.

[0092] In some embodiments, the first capacitor includes a first sub-capacitor Ca and a second sub-capacitor Cb, which are respectively disposed on both sides of the first inductor Lb.

[0093] In some embodiments, the first transistor and the second transistor may be MOSFETs or bipolar transistors.

[0094] In the embodiments of this application, please continue to refer to FIG6. The battery management circuit shown in FIG6 can be applied to the charging or discharging process of battery 100. The battery management circuit consists of a series optimizer and a centralized controller. The bidirectional DC / DC converter circuit in the series optimizer is a non-isolated bidirectional buck / boost topology, which includes a local controller. The positive terminal of battery 100 is connected to port ① of the series optimizer, the negative terminal of battery 100 is connected to port ② of the series optimizer, and ports ③ and ④ of the series optimizer are the positive and negative terminals of the output voltage, respectively. Ports ② and ④ are connected together. The power switches Q1 and Q2 and their body diodes D1 and D2, the energy storage inductor Lb, and the input filter capacitor Ca and the output filter capacitor Cb constitute the non-isolated bidirectional buck / boost circuit. The series optimizer's port ① is connected to the internal positive terminal of Ca and one end of the energy storage inductor Lb; ports ② and ④ are connected to the internal source (S) of Q2 and the negative terminals of Ca and Cb; port ③ is connected to the internal positive terminal of Cb and the drain (D) of Q1; and the source terminal of Q1 is connected to the drain terminal of Q2 and the other end of Lb. The battery current sampling signal is ib, and the output voltage sampling signal is Vo. The centralized controller consists of two internal functional units, including the SoC / SoH management unit U1 and the logic control unit U2. The local controller consists of eight internal functional units, five adders, and other components, including the SoC / SoH droop calculation unit U3, the output voltage droop calculation unit U4, the SoC / SoH calculation unit U5, the output voltage control compensation unit U6, the battery current control compensation unit U7, the sawtooth wave generator U8, the PWM wave generation unit U9, the drive unit U9, and other peripheral circuits.

[0095] During the charging process, energy is supplied by the DC bus 500, and the bidirectional DC / DC converter circuit operates in buck mode. In this mode, the power switch (corresponding to the second transistor) is the main switch, and the power switch (corresponding to the first transistor) is the synchronous rectifier. In each switching cycle, the first transistor turns on slightly after its body diode has turned on, thus enabling zero-voltage switching (ZVS). The local controller controls the second transistor to operate in a high-frequency PWM switching state: when the second transistor is on, the second sub-capacitor Cb provides energy to the battery 100, while the energy storage inductor (corresponding to the first inductor Lb) stores energy. When the second transistor is off, the energy stored in the first inductor Lb discharges and freewheels to the battery 100 through the synchronous rectifier and the first transistor.

[0096] During constant current charging, diode Di in the local controller is turned on and diode Dv is turned off. The current reference signal Idp (corresponding to the current control signal) is connected to the positive input terminal of adder U11, and the battery current negative feedback signal Ib (corresponding to the first current signal) is connected to the negative input terminal of adder U11. Its output terminal is connected to the first compensator, thus forming a battery constant current control loop. After the voltage error signal Ve is compared with the sawtooth wave signal of the generator, the comparator generates a pulse width modulation (PWM) signal, which is then amplified by the drive unit U10 to drive the first transistor and the second transistor.

[0097] After detecting parameters such as battery voltage, current, power and temperature, the local controllers report their respective SoC / SoH parameters to the central controller after passing through the first calculation unit 310. The central controller generates SoCmax (maximum charge signal) and SoCmin (minimum charge signal), charging and discharging control signals, DC bus 500 voltage (Vbus) and battery 100 quantity (n) data through the management unit 410 (corresponding to management unit U1), and then sends them to each local controller.

[0098] After receiving the SoCmax and SoCmin signals, the local controller sends one signal directly to the first sub-computing unit, and the other signal is subtracted from the SoCmax signal by adder U16 (corresponding to the third adder) and multiplied by the coefficient k before also entering the first sub-computing unit. Upon receiving the charging and discharging control signals, the local controller turns on switch k1 and turns off switch k2, causing the first sub-computing unit to generate the SoC / SoH droop voltage control signal. This signal is then converted into a droop current control signal (corresponding to the first sub-control signal) via coefficient 1 / m1 and enters the first input terminal of adder U12.

[0099] After receiving the Vbus and n signals, the local controller performs a division operation to obtain the average bus voltage Vbus / n (500V), which is then input to the negative input of adder U13. The local controller also generates another voltage reference signal, Vf, which is input to the positive input of U13. Vf is set as the upper limit of the output voltage. The output of U13 is converted into a droop current control signal via U4 and a coefficient of 1 / m2, and then input to the second input of U12. The local controller generates its own current reference signal Iref, which is directly input to the third input of U12. The local controller generates a current reference signal Idp, which is used by U7 to achieve constant current closed-loop control of the battery. Combined with their respective SoC / SoH and output voltage droop control methods, the battery SoC / SoH balance and output voltage balance are ultimately achieved.

[0100] During discharge, energy is supplied by battery 100, and the bidirectional DC / DC converter circuit operates in boost mode. In this mode, power switch Q2 is the primary switch, and power switch Q1 is the synchronous rectifier. Each switching cycle, Q1 turns on slightly after its body diode D1 has turned on, thus achieving zero-voltage switching (ZVS). The local controller controls Q2 to operate in a high-frequency PWM switching state: when Q2 is on, battery 100 stores energy in the energy storage inductor Lb; when Q2 is off, the energy stored in Lb is released to Cb through the synchronous rectifier Q1.

[0101] In the local controller, diode Di is off and diode Dv is on. Control switch k1 is off and k2 is on. The outputs of U3 and U4, along with Vref, enter the input of adder U14. Its output generates a voltage reference signal Vdp, which is connected to the positive input of adder U15. The output voltage negative feedback signal Vo is connected to the negative input of U15, and its output is connected to U6, thus forming an output voltage control loop. PWM signals are then emitted from U8, U9, and U10 to drive Q2 and Q1. Each local controller also receives and executes instructions and data from the central controller, using an independent closed-loop control method to boost its own output voltage. Combined with its own SoC / SoH and output voltage droop control methods, it ultimately achieves battery SoC / SoH balance and output voltage balance. Then, all output voltages are connected in series, forming a 500V DC bus. Its working principle is basically similar to constant current charging, and will not be elaborated further here.

[0102] In some embodiments, compensation units U6 and U7 can employ second-order or multi-order proportional-integral (PI) compensation or other control compensation methods. The aforementioned local controller uses voltage-mode control, but can also employ average current-mode, peak current-mode control, quasi-resonant control, single-cycle control, etc., to improve its dynamic response performance. The bidirectional DC / DC converter circuit can also employ different operating modes, such as continuous conduction mode (CCM), discontinuous conduction mode (DCM), or critical conduction mode (CRM), without affecting the performance and effectiveness of the series optimizer. The series optimizer differs fundamentally from the parallel optimizer; its bidirectional DC / DC converter circuit has a smaller voltage ratio, achieving high efficiency, small size, and low cost. Furthermore, the two-stage control method of centralized and local controllers is simple and flexible, facilitating battery system capacity expansion.

[0103] In some embodiments of this application, please refer to FIG9, which shows a schematic diagram of the circuit structure of the voltage conversion module 200 provided in this embodiment; the first transistor in this embodiment includes a first sub-transistor Q21 and a second sub-transistor Q22, which are respectively disposed on both sides of the first inductor Lb.

[0104] In some embodiments, please continue to refer to FIG9. The second transistor in this embodiment includes a third sub-transistor Q11 and a fourth sub-transistor Q12, which are respectively disposed on both sides of the first inductor Lb.

[0105] In some embodiments of this application, please continue with Figure 10. The voltage conversion unit of this embodiment includes a first converter 210 and a second converter 220. The first converter 210 is connected to the battery 100. The second converter 220 is connected to the bus 500 or the electrical equipment and is mutually inducted with the first converter 210. The first converter 210 is used to invert the first DC current output by the battery 100 into a first AC current. The second converter 220 is used to generate a second AC current based on the first AC current and to convert the second AC current into a second DC current for output to the electrical equipment.

[0106] Alternatively, the second converter 220 is used to invert the third DC current output from the bus 500 into a third AC current, and the first converter 210 is used to generate a fourth AC current based on the third AC current, and to convert the fourth AC current into a fourth DC current for output to the battery 100.

[0107] Please refer to Figure 10. From left to right, there are a first converter 210 and a second converter 220. When the battery 100 discharges, the electrical energy is transmitted from left to right. The first DC current output by the battery 100 is converted into a first AC current by adjusting the transistor in the first converter 210 on the left. Then, the first AC current is converted into a second AC current by the transformer in the middle. Finally, the second AC current is converted into a second DC current by adjusting the transistor in the second converter 220 on the right.

[0108] When the battery 100 is charging, the electrical energy is transmitted from right to left. The third DC current output by the bus 500 is inverted into the third AC current by adjusting the transistor in the second converter 220 on the right. Then, the third AC current is converted into the fourth AC current by the transformer in the middle. Finally, the fourth AC current is converted into the fourth DC current by adjusting the transistor in the first converter 210 on the right.

[0109] The transistors in any of the above embodiments can be fully controllable devices, such as field-effect transistors (MOSFETs) and insulated-gate bipolar transistors (IGBTs); the bidirectional DC / DC converter circuit can use interleaved parallel technology, series connection, or various three-level conversion circuits to achieve higher power levels or higher voltage levels.

[0110] In some embodiments, the battery 100 can be a cell, a battery pack, a battery cluster, or a battery module; the cells are connected in series and parallel to increase voltage and current to form a battery module, the battery modules are also connected in series and parallel to increase voltage and current to form a battery cluster, and finally, multiple parallel battery clusters form a battery module.

[0111] Furthermore, in order to better implement the battery management circuit in any of the above embodiments, this embodiment also provides an energy storage system based on the battery management circuit described above. The energy storage system includes multiple batteries and the battery management circuit described above. The battery management circuit is used to adjust the electrical parameters of the batteries, which are charging electrical parameters or discharging electrical parameters.

[0112] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0113] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0114] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0115] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0116] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A battery management circuit, characterized by, A battery management circuit for managing a plurality of batteries, the battery management circuit comprising: a plurality of voltage conversion modules, each of the plurality of voltage conversion modules corresponding to one of the plurality of batteries, each of the plurality of voltage conversion modules having a direct current side and a bus side, the direct current side being configured to be connected to the corresponding one of the plurality of batteries, the bus side being configured to be connected to a bus, the bus sides of the plurality of voltage conversion modules being connected in series to the bus; a plurality of first control modules, each of the plurality of first control modules corresponding to one of the plurality of voltage conversion modules; a second control module configured to obtain electrical parameters of the plurality of batteries and output a first control signal based on the electrical parameters, wherein each of the plurality of first control modules is configured to receive and respond to the first control signal to control the corresponding one of the plurality of voltage conversion modules to adjust the electrical parameters of the corresponding one of the plurality of batteries, the electrical parameters including one or more of voltage, current, temperature, and power.

2. The battery management circuit of claim 1, wherein, The first control module comprises: a first calculation unit configured to obtain the electrical parameters of the battery connected to the corresponding one of the plurality of voltage conversion modules; a second calculation unit configured to receive and output a second control signal based on the first control signal; an execution unit configured to receive and control the corresponding one of the plurality of voltage conversion modules to adjust the electrical parameters of the corresponding one of the plurality of batteries based on the second control signal. The second control module comprises a management unit configured to obtain the electrical parameters and output a maximum charge signal and a minimum charge signal based on the electrical parameters, and the second calculation unit is configured to output the second control signal based on the maximum charge signal and the minimum charge signal.

3. The battery management circuit of claim 2, wherein, The second control module further comprises a logic unit configured to output a bus voltage signal and a number of the plurality of batteries. The second calculation unit is further configured to receive the bus voltage signal and the number of the plurality of batteries and output the second control signal based on the bus voltage signal, the number of the plurality of batteries, and the maximum charge signal and the minimum charge signal.

4. The battery management circuit of claim 3, wherein, The second control signal comprises a current control signal and a voltage control signal, and the second calculation unit comprises: a first sub-calculation unit configured to obtain the maximum charge signal and the minimum charge signal and output a first sub-control signal based on the maximum charge signal and the minimum charge signal; a second sub-calculation unit configured to receive the bus voltage signal and the number of the plurality of batteries and output a second sub-control signal based on the bus voltage signal and the number of the plurality of batteries; a first adder configured to obtain and output the current control signal based on the first sub-control signal and the second sub-control signal; a second adder configured to obtain and output the voltage control signal based on the first sub-control signal and the second sub-control signal.

5. The battery management circuit of claim 4, wherein, The first calculation unit is further configured to output a first reference voltage and a first reference current. The first adder is configured to obtain and output the current control signal based on the first sub-control signal, the second sub-control signal, and the first reference current. The second adder is configured to obtain and output the voltage control signal based on the first sub-control signal and the second sub-control signal. And / or, the second adder is configured to obtain and output the voltage control signal according to the first sub-control signal, the second sub-control signal and a first reference voltage.

6. The battery management circuit of claim 4 or 5, wherein, The second calculation unit further comprises: a third adder configured to obtain and add the maximum charge signal and the minimum charge signal to obtain a first operation signal; a multiplier configured to obtain the first operation signal and multiply the first operation signal by a preset coefficient to output a second operation signal; and 7. The battery management circuit of any one of claims 2 to 5, wherein, the first sub-calculation unit is configured to output the first sub-control signal according to the maximum charge signal, the minimum charge signal and the second operation signal. The second control signal comprises a current control signal and a voltage control signal, and the execution unit comprises: a generator configured to output a periodic sawtooth wave; a first compensator configured to receive the current control signal and a first current signal of the battery and output a first compensation signal according to the current control signal and the first current signal; a second compensator configured to receive the voltage control signal and a first voltage signal of the battery and output a second compensation signal according to the voltage control signal and the first voltage signal; 8. The battery management circuit of claim 1, wherein, a comparator configured to output a first execution signal according to the sawtooth wave and the first compensation signal, the first execution signal being used to adjust the current of the voltage conversion unit; and the comparator is configured to output a second execution signal according to the sawtooth wave and the second compensation signal, the second execution signal being used to adjust the voltage of the voltage conversion unit. The voltage conversion unit is a non-isolated topology, and the voltage conversion unit comprises: a first inductor connected between the positive electrode of the battery and the positive electrode of the busbar; a first capacitor having one end connected between the positive electrode of the battery and the positive electrode of the busbar and the other end connected between the negative electrode of the battery and the negative electrode of the busbar; a first transistor connected in parallel with the first capacitor and configured to receive a third control signal output by a first control module to adjust the voltage and / or current of the battery; 9. The battery management circuit of claim 1, wherein, And / or, the first transistor comprises a first sub-transistor and a second sub-transistor, and the first sub-transistor and the second sub-transistor are arranged on two sides of the first inductor. The voltage conversion unit is an isolated topology, and the voltage conversion unit comprises: a first converter connected to the battery; a second converter connected to the busbar or the electrical equipment and magnetically coupled with the first converter; the first converter is configured to invert a first direct current output by the battery into a first alternating current; and the second converter is configured to form a second alternating current according to the first alternating current and convert the second alternating current into a second direct current to output to the electrical equipment. Alternatively, the second converter is configured to convert a third direct current output by the bus into a third alternating current, the first converter is configured to generate a fourth alternating current based on the third alternating current, and configured to convert the fourth alternating current into a fourth direct current for output to the battery.

10. An energy storage system characterized by, The energy storage system comprises a plurality of batteries and the battery management circuit according to any one of claims 1 to 9, wherein the battery management circuit is configured to adjust an electrical parameter of the battery, the electrical parameter being a charging electrical parameter or a discharging electrical parameter.

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