Battery management circuit and energy storage system

Abstract

Provided in the present application are a battery management circuit and an energy storage system. The battery management circuit comprises voltage conversion modules, a power frequency commutation module and a first control module. Each voltage conversion module has a plurality of voltage conversion units; when the voltage conversion module is in a first operating state, the plurality of voltage conversion units are connected in series; and when the voltage conversion module is in a second operating state, the plurality of voltage conversion units are connected in parallel. The power frequency commutation module comprises a direct-current side for connecting to the plurality of voltage conversion modules, and an alternating-current side for outputting or inputting electric energy. The first control module is used for sampling an electric energy signal on the alternating-current side or receiving an external control signal. During high-voltage charging of each battery or high-voltage output from the battery, the plurality of voltage conversion units are connected in series; and during low-voltage charging of each battery or low-voltage output from the battery, the plurality of voltage conversion units are connected in parallel. Adjusting the connection relationship between a plurality of batteries enables the batteries as a whole to perform output or input in an optimal structure, thereby improving the overall charging and discharging performance of the batteries.

Description

A battery management circuit and energy storage system

[0001] This application claims priority to Chinese Patent Application No. 202410853698.5, filed on June 28, 2024, entitled "A Battery Management Circuit and Energy Storage System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of battery management technology, and in particular relates to a battery management circuit and energy storage system. Background Technology

[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] In series connection, multiple batteries are connected end-to-end to form a battery cluster, which is then connected to the bus via a DC / DC converter circuit. However, performance differences and uneven aging rates among the individual batteries often severely impact the performance of the entire battery cluster, a phenomenon known as the "weakest link effect." In parallel connection, each battery is equipped with an independent DC / DC circuit, and these circuits are then connected in parallel to the bus. However, if too many batteries are connected in parallel, the weakest link effect still cannot be avoided.

[0005] Therefore, how to improve the overall charge and discharge performance of batteries is a problem that needs to be solved by those skilled in the art. Technical issues

[0006] The purpose of this application is to provide a battery management circuit and energy storage system, which aims to solve the problem of poor overall charge and discharge performance of batteries in conventional technologies. Technical solutions

[0007] A first aspect of this application provides a battery management circuit for managing multiple batteries, the battery management circuit comprising:

[0008] A voltage conversion module has multiple voltage conversion units, each of which is connected to a corresponding battery. The voltage conversion module has a first operating state and a second operating state. The voltage conversion module is configured such that, in the first operating state, the multiple voltage conversion units are connected in series, and in the second operating state, the multiple voltage conversion units are connected in parallel.

[0009] A power frequency commutation module, comprising a DC side and an AC side, wherein the DC side is used to connect multiple voltage conversion modules, and the AC side is used to output or input electrical energy;

[0010] A first control module is configured to sample the power signal on the AC side or receive external control signals. The first control module is configured to control the voltage conversion module to switch to a first operating state when the power signal is a high-level signal; and to control the voltage conversion module to switch to a second operating state when the power signal is a low-level signal. Alternatively, the first control module is configured to adjust the switching of the voltage conversion module between the first and second operating states according to the control signal.

[0011] In some embodiments of this application, the plurality of batteries include a first battery and a second battery, wherein the electrical parameters of the first battery are superior to those of the second battery, and the electrical parameters include charge or health status.

[0012] The voltage conversion module includes a first voltage conversion unit and a second voltage conversion unit. The first voltage conversion unit is used to connect to the first battery, and the second voltage conversion unit is used to connect to the second battery.

[0013] Wherein, the voltage conversion module is configured to output electrical energy on the AC side, and when the voltage conversion module is in the first working state, the first voltage conversion unit is located closer to the negative terminal of the DC side than the second voltage conversion unit;

[0014] The voltage conversion module is configured to input electrical energy on the AC side, and when the voltage conversion module is in the first working state, the first voltage conversion unit is located closer to the positive terminal of the DC side than the second voltage conversion unit.

[0015] In some embodiments of this application, the first battery is the battery with the best electrical parameters among the plurality of batteries, and the second battery is the battery with the worst electrical parameters among the plurality of batteries;

[0016] Wherein, the voltage conversion module is configured to output electrical energy on the AC side, and when the voltage conversion module is in the first working state, the first voltage conversion unit is connected to the negative terminal of the DC side, and the second voltage conversion unit is connected to the positive terminal of the DC side;

[0017] The voltage conversion module is configured to input electrical energy on the AC side. When the voltage conversion module is in the first working state, the first voltage conversion unit is connected to the positive terminal of the DC side, and the second voltage conversion unit is connected to the negative terminal of the DC side.

[0018] In some embodiments of this application, the voltage conversion module further has a third operating state, wherein the voltage conversion module is configured such that, in the third operating state, some of the voltage conversion units are connected in parallel and some of the voltage conversion units are connected in series.

[0019] The first control module is also used to adjust the voltage conversion module to the third working state according to the power signal on the AC side or the external control signal.

[0020] In some embodiments of this application, the battery management circuit further includes a plurality of second control modules, each corresponding to a plurality of voltage conversion units. The second control modules are used to receive and respond to the drive signals of the first control module to adjust the connection relationship between the voltage conversion unit and another adjacent voltage conversion unit, so as to switch the voltage conversion module to different working states.

[0021] In some embodiments of this application, the voltage conversion unit includes:

[0022] The positive electrode wire has one end connected to the positive terminal of the battery and the other end used to connect to the positive terminal of the DC side.

[0023] The negative terminal wire has one end connected to the negative terminal of the battery and the other end connected to the negative terminal of the DC side.

[0024] The first capacitor has one end connected to the positive line and the other end connected to the negative line;

[0025] A first power switch is disposed on the positive line or the negative line and is used to control the on / off state of the positive line;

[0026] The second power switch is disposed between the positive line and the negative line, and is connected in series with another voltage conversion unit through the negative line. The second power switch is used to control the on / off state between the positive line and the negative line.

[0027] The third power switch is connected at one end to the positive line and at the other end to another voltage conversion unit in parallel. The third power switch is configured to adjust the on / off state of the two ends of the third power switch under the control of the first control module.

[0028] In some embodiments of this application, the voltage conversion unit further includes a first inductor, which is disposed on the positive line or the negative line;

[0029] At least two first power switching transistors are provided, and at least two first power switching transistors are connected in series on the positive line or the negative line; or at least one first power switching transistor is provided on the positive line and at least one first power switching transistor is provided on the negative line.

[0030] And / or, the number of the first capacitors is at least two, and at least two of the first capacitors are connected in parallel between the positive line and the negative line;

[0031] And / or, at least two second power switches are provided, and at least two second power switches are connected in parallel between the positive line and the negative line.

[0032] In some embodiments of this application, the voltage conversion unit further includes a fourth power switch.

[0033] The first inductor and at least one first power switch are both disposed on the positive line, and the fourth power switch is disposed at the end of the first inductor away from the first power switch.

[0034] Alternatively, the first inductor and at least one of the first power switches are disposed on the negative line, and the fourth power switch is disposed at the end of the first inductor away from the first power switch.

[0035] In some embodiments of this application, the voltage conversion circuit includes a first converter and a second converter, wherein the first converter is connected to the battery and the second converter is connected to the power frequency commutation module;

[0036] The first converter is used to invert the first DC current output by the battery into a first AC current; the second converter 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 power frequency commutation module.

[0037] Alternatively, the second converter is used to invert the third DC current output by the power frequency commutation module into a third AC current, and the first converter 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.

[0038] Secondly, this application also provides an energy storage system, which includes a plurality of batteries and the aforementioned battery management circuit, wherein the battery management circuit is used to manage the plurality of batteries. Beneficial effects

[0039] The beneficial effects of the present invention embodiments 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 a voltage conversion module, a power frequency commutation module, and a first control module. The voltage conversion module has multiple voltage conversion units, which are connected one-to-one with multiple batteries. The voltage conversion module has a first operating state and a second operating state. The voltage conversion module is configured such that, in the first operating state, the multiple voltage conversion units are connected in series; and in the second operating state, the multiple voltage conversion units are connected in parallel. The power frequency commutation module includes a DC side and an AC side. The DC side is used to connect multiple voltage conversion modules, and the AC side is used to output or input electrical energy. The first control module is used to sample the electrical energy signal on the AC side or receive external control signals. The control module is configured to switch the voltage conversion module to a first operating state when the power signal is high, and to switch the voltage conversion module to a second operating state when the power signal is low; or the first control module is configured to adjust the switching between the first and second operating states of the voltage conversion module according to the control signal. In other words, this application can connect multiple voltage conversion units in series to match a high-level voltage when the battery is being charged at high voltage or when it is outputting at high voltage; and connect multiple voltage conversion units in parallel to match a low-level voltage when the battery is being charged at low voltage or when it is outputting at low voltage. This application improves the overall charging and discharging performance of the battery by adjusting the connection relationship between multiple batteries to achieve optimal output or input structure for the battery as a whole. Attached Figure Description

[0040] Figure 1 is a schematic diagram of the circuit structure of the battery management circuit provided in the relevant technology of this application;

[0041] Figure 2 is a schematic diagram of the circuit structure of a battery management circuit provided by another related technology of this application;

[0042] Figure 3 is a schematic diagram of the circuit structure of a battery management circuit provided in an embodiment of this application;

[0043] Figure 4 is a schematic diagram of the framework structure of a battery management circuit provided in an embodiment of this application;

[0044] Figure 5 is a schematic diagram of another frame structure of the battery management circuit provided in an embodiment of this application;

[0045] Figure 6 is a schematic diagram of the circuit structure of a battery conversion module provided in an embodiment of this application;

[0046] Figure 7 is a schematic diagram of the circuit structure of a battery conversion module provided in another embodiment of this application;

[0047] Figure 8 is a schematic diagram of the circuit structure of a battery conversion module provided in another embodiment of this application;

[0048] Figure 9 is a schematic diagram of the circuit structure of a battery conversion module provided in another embodiment of this application;

[0049] Figure 10 is a schematic diagram of the circuit structure of a battery conversion module provided in another embodiment of this application;

[0050] Figure 11 is a schematic diagram of the circuit structure of a battery conversion module provided in another embodiment of this application;

[0051] Figure 12 is a schematic diagram of the circuit structure of a battery conversion module provided in yet another embodiment of this application;

[0052] Figure 13 is a schematic diagram of the circuit structure of a battery conversion module provided in another embodiment of this application;

[0053] Figure 14 is a schematic diagram of the circuit structure of a power frequency commutation module provided in an embodiment of this application;

[0054] Figure 15 is a schematic diagram of the circuit structure of a high-frequency filtering circuit provided in an embodiment of this application.

[0055] Specific element symbols: 100 - battery, 200 - voltage conversion module, 300 - power frequency commutation module, 400 - first control module, L1 - first inductor, Q3 - first power switch, Q4 - second power switch, Q5 - third power switch, Q6 - fourth power switch, Cb - first capacitor. Embodiments of the present invention

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] It's important to understand that with the rapid advancements in technology and the widespread adoption of modern electronic devices and electric vehicles, the demands on battery performance are becoming increasingly stringent. As the core power source for these devices, the performance of the battery directly determines their operating efficiency and lifespan. To address the varying voltage and capacity requirements of different devices, we typically combine multiple batteries using specific connection methods to form more powerful battery packs.

[0061] Series connection, one of the most common battery connection methods, involves connecting the positive and negative terminals of multiple batteries end-to-end. This connection method can significantly increase the total voltage of the battery pack, meeting the requirements of high-voltage devices. However, each battery exhibits certain performance differences during manufacturing, such as capacity, internal resistance, and charge / discharge efficiency, and these batteries also age at different rates over time. These minute differences are amplified in a series circuit, leading to overcharging and over-discharging of some batteries, thus severely impacting the performance of the entire battery cluster. The performance of the entire battery cluster often depends on the worst-performing battery, a phenomenon known as the "weakest link" effect.

[0062] 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.

[0063] To mitigate the "weakest link" problem, parallel connection was proposed. In this method, each battery has an independent DC / DC converter circuit. These circuits adjust the battery's voltage and current to match the bus level before connecting them in parallel. While this approach can balance the performance differences between individual batteries to some extent, it's still difficult to completely avoid the "weakest link" effect if too many batteries are connected in parallel. Even with an independent DC / DC circuit for each battery, performance differences and uneven aging rates within the batteries still exist, impacting the overall performance of the battery pack.

[0064] 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 high system cost, and the current sharing control method of the parallel output is also more complex. In addition, if too many batteries are connected in series and parallel, the weakest link effect will inevitably exist.

[0065] Therefore, this application improves the relevant battery management circuit and energy storage system based on this.

[0066] 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 framework structure of the battery 100 management circuit provided in this embodiment. Figure 5 shows another schematic diagram of the framework structure of the battery 100 management circuit provided in this embodiment. Specifically, the buck-boost converter in Figure 3 corresponds to the voltage conversion module 200 in this application, the power frequency commutation circuit corresponds to the power frequency commutation module 300 in this application, and the main controller corresponds to the first control module 400 in this application. Figure 4 shows a schematic diagram of multiple batteries 100 and their voltage conversion units connected in series, and Figure 5 shows a schematic diagram of multiple batteries 100 and their voltage conversion units connected in parallel.

[0067] The battery 100 management circuit of this embodiment manages multiple batteries 100. The battery 100 management circuit includes a voltage conversion module 200, a power frequency commutation module 300, and a first control module 400. The voltage conversion module 200 has multiple voltage conversion units, each connected to one of the multiple batteries 100. The voltage conversion module 200 has a first operating state and a second operating state. In the first operating state, the multiple voltage conversion units are connected in series; in the second operating state, the multiple voltage conversion units are connected in parallel. The power frequency commutation module 300 includes a DC... The DC side is used to connect multiple voltage conversion modules 200, and the AC side is used to output or input electrical energy. The first control module 400 is used to sample the electrical energy signal on the AC side or receive external control signals. The first control module 400 is configured to control the voltage conversion module 200 to switch to a first operating state when the electrical energy signal is a high-level signal; and to control the voltage conversion module 200 to switch to a second operating state when the electrical energy signal is a low-level signal; or the first control module 400 is configured to adjust the switching of the voltage conversion module 200 between the first and second operating states according to the control signal.

[0068] It should be explained that the voltage conversion module 200 is used for boosting or bucking the voltage; the power frequency commutation module 300 is used for rectification or inversion. The first control module 400 can control multiple voltage conversion units separately.

[0069] In current battery management circuits, multiple batteries 100 are either connected in series or in parallel, making it difficult to achieve stable performance of the battery 100 under different power demands. However, this application can connect multiple voltage conversion units in series to match the high-level voltage when the battery 100 is charging at high voltage or outputting at high voltage; and connect multiple voltage conversion units in parallel to match the low-level voltage when the battery 100 is charging at low voltage or outputting at low voltage. By adjusting the connection relationship between multiple batteries 100, this application enables the battery 100 to output or input in an optimal structure, thereby improving the overall charging and discharging performance of the battery 100.

[0070] In an exemplary embodiment, the battery 100 management system is used to manage at least four batteries 100. Assuming that the voltage of each battery 100 is E, if the battery 100 needs to output 4E, then the four batteries 100 and their corresponding voltage conversion units are connected in series, and the batteries 100 output 4E after being connected in series. If the battery 100 needs to output E, then the four batteries 100 and their corresponding voltage conversion units are connected in parallel, and the batteries 100 output E after being connected in parallel.

[0071] In some embodiments of this application, the plurality of batteries 100 includes a first battery 100 and a second battery 100, wherein the electrical parameters of the first battery 100 are superior to those of the second battery 100, and the electrical parameters include charge or health status; the voltage conversion module 200 includes a first voltage conversion unit and a second voltage conversion unit, wherein the first voltage conversion unit is used to connect to the first battery 100, and the second voltage conversion unit is used to connect to the second battery 100; wherein the voltage conversion module 200 is configured to output electrical energy on the AC side, and when the voltage conversion module 200 is in a first operating state, the first voltage conversion unit is positioned closer to the negative terminal on the DC side than the second voltage conversion unit; the voltage conversion module 200 is configured to input electrical energy on the AC side, and when the voltage conversion module 200 is in the first operating state, the first voltage conversion unit is positioned closer to the positive terminal on the DC side than the second voltage conversion unit.

[0072] For example, during inverter discharge or rectifier charging, the main controller issues instructions to the slave controller based on the state of charge / health (SOC / SOH) information of each battery 100, controlling the logic sequence of the corresponding buck-boost converters. During discharge / charge, the battery 100 with the highest / lowest SOC is placed at the bottom layer of a multi-level stepped waveform for sinusoidal pulse width modulation (SPWM), while the battery 100 with the lowest / highest SOC is placed at the top layer of SPWM. The bottom layer means more charging and discharging, and the top layer means less charging and discharging. The buck-boost converters of other batteries 100 are arranged in sequence according to this rule, so that the high-capacity battery 100 discharges more and charges less, and the low-capacity battery 100 discharges less and charges more, thereby realizing the SOC / SOC balancing and management function of the battery 100. This control strategy can also realize the mixing of new and old batteries 100.

[0073] In some embodiments of this application, the first battery 100 is the battery 100 with the best electrical parameters among a plurality of batteries 100, and the second battery 100 is the battery 100 with the worst electrical parameters among a plurality of batteries 100; wherein, the voltage conversion module 200 is configured to output electrical energy on the AC side, and when the voltage conversion module 200 is in a first working state, the first voltage conversion unit is connected to the negative terminal of the DC side, and the second voltage conversion unit is connected to the positive terminal of the DC side; the voltage conversion module 200 is configured to input electrical energy on the AC side, and when the voltage conversion module 200 is in a first working state, the first voltage conversion unit is connected to the positive terminal of the DC side, and the second voltage conversion unit is connected to the negative terminal of the DC side.

[0074] In some embodiments of this application, the voltage conversion module 200 also has a third operating state. The voltage conversion module 200 is configured such that, in the third operating state, some of the multiple voltage conversion units are connected in parallel and some of the multiple voltage conversion units are connected in series. The first control module 400 is also used to adjust the voltage conversion module 200 to the third operating state according to the power signal on the AC side or an external control signal.

[0075] In related technologies, the multi-level stepped waveform of a cascaded inverter corresponds to frequent charging and discharging of battery 100, requiring periodic changes to the logic order of all cascaded converters. This results in a complex balancing control strategy, and the more converters there are, the slower the balancing response. In this example, the battery 100 management system manages at least four batteries 100. Assuming each battery 100 has a voltage of E, if a battery 100 needs to output 2E, the corresponding switch is turned on, making two batteries 100 equivalent to series connection and two groups of batteries 100 equivalent to parallel connection. The series connection of the batteries 100 then outputs 2E. If a battery 100 needs to output 3E, the corresponding switch is turned on, making three of the four batteries 100 equivalent to series connection. The fourth battery 100 then uses the aforementioned balancing strategy to control its logic order. Therefore, this balancing implementation method can dynamically change the connection relationship of the switches in the three-port buck-boost converter, flexibly equivalent to series or parallel connection, thereby simplifying the balancing control strategy and accelerating the balancing response.

[0076] In some embodiments, the battery 100 can be a cell, a battery pack, a battery cluster, or a battery group. Specifically, multiple cells form a battery pack, multiple battery packs form a battery cluster, and multiple battery clusters form a battery group.

[0077] In some embodiments of this application, please continue to refer to FIG3. The battery 100 management circuit of this embodiment also includes a plurality of second control modules. The plurality of second control modules correspond one-to-one with a plurality of voltage conversion units. The second control modules are used to receive and respond to the drive signals of the first control module 400 to adjust the connection relationship between the voltage conversion unit and another adjacent voltage conversion unit, so as to switch the voltage conversion module 200 to different working states.

[0078] It should be explained that the slave controller in Figure 3 is equivalent to the second control module in this application. The controller is divided into a master controller and a slave controller, including sampling, conditioning and feedback circuits, and switching transistor drive circuits, etc. The master and slave controllers have wired or wireless communication. The master controller samples the AC side signal, controls the logic sequence of each buck-boost converter, controls the internal switching transistors of the power frequency commutation circuit, realizes closed-loop control of charging or discharging of battery 100, and realizes external communication. The slave controller detects parameters such as voltage, current, power and temperature of battery 100, calculates the state of charge / health (SOC / SOH), which is equivalent to completing the battery 100 management function, and then reports its own SOC / SOH and other battery 100 parameters to the master controller, and receives and executes the instructions and data issued by the master controller, such as charging / discharging control, buck-boost converter logic sequence arrangement, stepped wave output voltage and battery 100 quantity information, and controls the operation of each switching transistor inside the buck-boost converter.

[0079] In some embodiments of this application, please refer to Figure 6, which shows a schematic diagram of the circuit structure of the voltage conversion unit provided in this embodiment. The voltage conversion unit of this embodiment includes: a positive line, one end of which is connected to the positive terminal of the battery 100, and the other end of which is used to connect to the positive terminal of the DC side; a negative line, one end of which is connected to the negative terminal of the battery 100, and the other end of which is used to connect to the negative terminal of the DC side; a first capacitor Cb, one end of which is connected to the positive line, and the other end of which is connected to the negative line; a first power switch Q3, which is disposed on the positive line or the negative line and is used to control the on / off state of the positive line; a second power switch Q4, which is disposed between the positive line and the negative line and is connected in series with another voltage conversion unit through the negative line, and the second power switch Q4 is used to control the on / off state between the positive line and the negative line; a third power switch Q5, one end of which is connected to the positive line, and the other end of which is used to connect in parallel with another voltage conversion unit; the third power switch Q5 is configured to adjust the on / off state of the two ends of the third power switch Q5 under the control of the first control module 400.

[0080] Example 1: Please refer to Figure 6. The positive terminal of battery 100 is connected to port ①, the negative terminal of battery 100 is connected to port ②, and ports ③ and ④ are the positive and negative terminals of the power frequency commutation module 300, respectively. Ports ② and ④ are connected together to form a negative line. Power switches Q3 (corresponding to the first power switch Q3), Q4 (corresponding to the second power switch Q4), and their body diodes form a bidirectional half-bridge cascaded circuit to achieve two output levels: high and low. Port ① is connected to the positive terminal of Cb (corresponding to the first capacitor Cb) and the drain (D) of Q3 and power switch Q5 (corresponding to the third power switch Q5). Ports ② and ④ are connected to the source (S) of Q4 and the negative terminal of Cb. Port ③ is connected to the source (S) of Q3 and the drain (D) of Q4. The source (S) of Q5 is connected to port ⑩ for connection with other voltage conversion units.

[0081] During the rectification and charging process, power is transferred from the output to the battery 100, supplied by a multi-level stepped wave bus. The bidirectional half-bridge cascaded circuit operates in boost mode, where power switch Q4 is the main switch and power switch Q3 is the synchronous rectifier. In each switching cycle, Q3 turns on slightly after its body diode D3 has turned on, thus achieving ZVS for Q3. The controller controls Q4 and Q5 to operate in a high-frequency PWM switching state: the half-bridge cascaded circuit utilizes the filter inductor in the high-frequency filter circuit as an energy storage inductor. When Q4 is on, the filter inductor stores energy, and Cb discharges to the input. When Q4 is off, the energy stored in the filter inductor discharges through the synchronous rectifier Q3 to Cb and the input as a freewheeling current. Rectification and charging can be performed using constant current or constant voltage methods, which are traditional control measures and will not be elaborated upon here.

[0082] During the inverter discharge process, when power is transferred from battery 100 to the output, energy is provided by battery 100. The bidirectional half-bridge cascaded circuit operates in buck mode, where power switch Q3 is the main switch and power switch Q4 is the synchronous rectifier. In each switching cycle, Q4 turns on slightly after its body diode D4 has turned on, thus achieving ZVS for Q4. The controller controls Q3 and Q5 to operate in high-frequency PWM switching mode: the half-bridge cascaded circuit can utilize the filter inductor in the high-frequency filter circuit as an energy storage inductor. When Q3 is on, Cb provides energy to the output, and the filter inductor stores energy. When Q3 is off, the energy stored in the filter inductor is discharged to the output through the synchronous rectifier Q4.

[0083] It should be noted that the battery 100 half-bridge cascade circuit adopts voltage mode control, but can also adopt average current mode, peak current mode control, quasi-resonant control, single-cycle control, etc. It can also adopt different operating modes, such as continuous current conduction mode (CCM), discontinuous current mode (DCM), or critical current conduction mode (CRM).

[0084] In some embodiments of this application, please refer to Figure 7, which shows a schematic diagram of the circuit structure of the voltage conversion unit provided in this embodiment. The voltage conversion unit in Figure 7 further includes a first inductor L1, which is disposed on the positive or negative line; at least two first power switches Q3 are provided, and at least two first power switches Q3 are connected in series on the positive or negative line; or at least one first power switch Q3 is disposed on the positive line and at least one first power switch Q3 is disposed on the negative line; and / or, at least two first capacitors Cb are provided, and at least two first capacitors Cb are connected in parallel between the positive and negative lines; and / or, at least two second power switches Q4 are provided, and at least two second power switches Q4 are connected in parallel between the positive and negative lines.

[0085] Example 2: Please refer to Figure 7. The difference between the voltage conversion unit in this example and the voltage conversion unit in Example 1 is that a first inductor L1 is provided, and the first inductor L1 is located on the positive line; and two first power switches Q3 are provided, and the two first power switches Q3 are connected in series on the positive line. Furthermore, two second power switches Q4 are provided, and the two second power switches Q4 are connected in parallel.

[0086] Example 3: Please refer to Figure 8, which shows a schematic diagram of the circuit structure of the voltage conversion unit provided in this example. The difference between the voltage conversion unit in this example and the voltage conversion unit in Example 2 is that the first inductor L1 is placed on the negative line, and there are two first power switches Q3, one on the positive line and the other on the negative line. Furthermore, there are two second power switches Q4 connected in parallel. During bidirectional inverter discharge and rectified charging, this circuit can achieve both unidirectional boost and buck voltage conversion.

[0087] In some embodiments of this application, please refer to FIG9, which shows a schematic diagram of the circuit structure of the voltage conversion unit provided in this embodiment; the voltage conversion unit of this embodiment further includes a fourth power switch Q6; the first inductor L1 and at least one first power switch Q3 are both disposed on the positive line, and the fourth power switch Q6 is disposed at the end of the first inductor L1 away from the first power switch Q3; or, the first inductor L1 and at least one first power switch Q3 are disposed on the negative line, and the fourth power switch Q6 is disposed at the end of the first inductor L1 away from the first power switch Q3.

[0088] Example 4: Please continue to refer to Figure 9. The difference between the voltage conversion unit in this example and the voltage conversion unit in Example 2 is that the voltage conversion unit further includes a fourth power switch Q6. The first inductor L1 and at least one first power switch Q3 are both located on the positive line, and the fourth power switch Q6 is located at the end of the first inductor L1 away from the first power switch Q3.

[0089] Example 5: Please refer to Figure 10, which shows a schematic diagram of the circuit structure of the voltage conversion unit provided in this example. The difference between the voltage conversion unit in this example and the voltage conversion unit in Example 3 is that the voltage conversion unit further includes a fourth power switch Q6, and the first inductor L1 and at least one first power switch Q3 are disposed on the negative line. The fourth power switch Q6 is disposed at the end of the first inductor L1 away from the first power switch Q3. The bidirectional LLC resonant circuit of this example achieves ZVS operation of all power switches, thereby further improving the converter conversion efficiency.

[0090] In some embodiments of this application, please refer to Figure 11, which is a schematic diagram of the circuit structure of the voltage conversion unit provided in this embodiment; from left to right in Figure 11, there are a first converter and a second converter. The voltage conversion circuit of this embodiment includes a first converter and a second converter. The first converter is connected to the battery 100, and the second converter is connected to the power frequency commutation module 300. The first converter is used to invert the first DC current output by the battery 100 into a first AC current; the second converter 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 power frequency commutation module 300; or, the second converter is used to invert the third DC current output by the power frequency commutation module 300 into a third AC current, and the first converter 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.

[0091] Example 6: Please refer to Figure 12, which shows a schematic diagram of the circuit structure of the voltage conversion unit provided in this example; the half-bridge cascaded circuit in this example can only generate two levels, while the full-bridge circuit can generate three levels.

[0092] Example 7: Please refer to Figure 13, which shows a schematic diagram of the circuit structure of the voltage conversion unit provided in this example; the voltage conversion unit of this example is applied to a three-phase hybrid circuit.

[0093] In some embodiments, referring to Figure 3, the battery 100 management circuit of this embodiment includes multiple three-port buck-boost converters, a power frequency commutation circuit, a high-frequency filter circuit, and a main controller. The power frequency commutation circuit internally consists of a full bridge composed of four switching transistors, and the high-frequency filter circuit consists of a filter inductor and a filter capacitor. The three-port buck-boost converters 1~n include power conversion circuits 1~n and slave controllers 1~n. Each power conversion circuit includes a cascaded circuit. The buck-boost circuit is connected to the battery 100, and the cascaded circuit is connected to the power frequency commutation circuit.

[0094] Please refer to Figures 14 and 15. Figure 14 shows a schematic diagram of the circuit structure of the power frequency commutation module 300 provided in this embodiment; Figure 15 shows a schematic diagram of the circuit structure of the high-frequency filter circuit provided in this embodiment. In this embodiment, the positive terminal ① and negative terminal ② of each input are connected to the positive and negative terminals of their respective batteries 100, respectively. The negative terminal ④ of the bottom step-up / step-down converter 1 is connected to the negative terminal of the stepped wave bus, and its positive terminal ③ is connected to the negative terminal ④ of the next step-up / step-down converter 2. Its positive terminal ③ is then connected to the negative terminal ④ of the next step-up / step-down converter, and so on. After the output voltages of multiple step-up / step-down converters are cascaded together, the positive terminal ③ of the top step-up / step-down converter n is connected to the positive terminal of the stepped wave bus. The three-port step-up / step-down converter also has a terminal ⑩. From the top to the bottom, the upper terminal ⑩ is connected to the lower terminal ① in a cascaded manner, thus forming a second branch.

[0095] During battery 100 inverter discharge: Each slave controller receives and executes instructions and data from the main controller, controlling its own output voltage. All buck-boost converter output voltages are cascaded to form a unipolar multi-level stepped wave bus voltage, which enters the full-bridge power frequency commutation circuit to form a symmetrical stepped wave with positive and negative half-cycles at power frequency. This wave then passes through a high-frequency filter circuit to form an output sinusoidal voltage, which is supplied to the load or connected to the AC power grid. The main waveforms from top to bottom are the unipolar stepped wave bus voltage, the symmetrical stepped wave with positive and negative half-cycles at power frequency, and the output sinusoidal voltage.

[0096] When the battery 100 is being rectified and charged: the input and output terminals of the buck-boost converter are interchanged, that is, the positive and negative input terminals are ports ③ and ④ respectively, and the positive and negative output terminals are ports ① and ② respectively. The AC grid provides a sinusoidal voltage, which passes through a high-frequency filter circuit and enters a full-bridge power frequency commutation circuit to form a unipolar multi-level stepped wave bus voltage. Each slave controller also receives and executes the instructions and data issued by the master controller, and then controls its respective battery 100 to be charged in constant current or constant voltage mode through all buck-boost converters that are cascaded with each other by the input voltage.

[0097] In some embodiments, the buck-boost circuit uses non-isolated or isolated DC-DC converter circuits (DC / DC), including but not limited to non-isolated topologies such as Buck, Boost, Buck-Boost, Cuk, SEPIC, and ZETA, and isolated topologies such as half-bridge, full-bridge, push-pull, flyback, forward, and forward-flyback, or combined with resonant circuits such as LLC, LCC, LCLC, CLCL, and basic series-parallel connections; the cascaded circuit uses full-bridge or half-bridge non-isolated topologies, in which case the ⑩th port of the second cascaded branch needs to be taken from its DC bus capacitor, as will be specifically described in the following embodiments. These topologies can use interleaved parallel technology and various three-level conversion circuits to achieve higher power levels. The master-slave two-stage control method is simple and flexible, easy to expand new control strategies, and convenient for expanding the capacity of the Battery 100 energy storage system. During bidirectional inverter discharge or rectifier charging, the bus voltage is a multi-level stepped wave, so the filter inductance in the high-frequency filter circuit is small, thereby reducing the cost of passive components. Each buck-boost converter has a relatively small output voltage, current, and power, which reduces the rated voltage of its internal power switching transistors. Simultaneously, there are no high-frequency switching losses in the power frequency commutation circuit, thereby improving conversion efficiency, reducing device size, and lowering system cost. Furthermore, the three-port buck-boost converter can use various types of batteries, including a mix of different types or a combination of new and old batteries.

[0098] In three-port buck-boost converters and power frequency commutation circuits, fully controllable devices such as MOSFETs and IGBTs are used as power switches. 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). They can be implemented using discrete components or integrated circuits, or integrated into a single controller to form a large-scale hybrid integrated circuit. This highly integrated controller design can further reduce device size.

[0099] Furthermore, in order to better implement the battery management circuit in any of the above embodiments, based on the above energy storage device, this embodiment also provides an energy storage system, which includes multiple batteries and the above-described battery management circuit, and the battery management circuit is used to manage the multiple batteries.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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 in that, For managing multiple batteries, the battery management circuit includes: A voltage conversion module has multiple voltage conversion units, each of which is connected to a corresponding battery. The voltage conversion module has a first operating state and a second operating state. The voltage conversion module is configured such that, in the first operating state, the multiple voltage conversion units are connected in series, and in the second operating state, the multiple voltage conversion units are connected in parallel. A power frequency commutation module, comprising a DC side and an AC side, wherein the DC side is used to connect multiple voltage conversion modules, and the AC side is used to output or input electrical energy; A first control module is configured to sample the power signal on the AC side or receive external control signals. The first control module is configured to control the voltage conversion module to switch to a first operating state when the power signal is a high-level signal; and to control the voltage conversion module to switch to a second operating state when the power signal is a low-level signal. Alternatively, the first control module is configured to adjust the switching of the voltage conversion module between the first and second operating states according to the control signal.

2. The battery management circuit according to claim 1, characterized in that, The plurality of batteries include a first battery and a second battery, wherein the electrical parameters of the first battery are superior to those of the second battery, and the electrical parameters include charge or health status; The voltage conversion module includes a first voltage conversion unit and a second voltage conversion unit. The first voltage conversion unit is used to connect to the first battery, and the second voltage conversion unit is used to connect to the second battery. Wherein, the voltage conversion module is configured to output electrical energy on the AC side, and when the voltage conversion module is in the first working state, the first voltage conversion unit is located closer to the negative terminal of the DC side than the second voltage conversion unit; The voltage conversion module is configured to input electrical energy on the AC side, and when the voltage conversion module is in the first working state, the first voltage conversion unit is positioned closer to the positive terminal of the DC side than the second voltage conversion unit.

3. The battery management circuit according to claim 2, characterized in that, The first battery is the battery with the best electrical parameters among the plurality of batteries, and the second battery is the battery with the worst electrical parameters among the plurality of batteries; Wherein, the voltage conversion module is configured to output electrical energy on the AC side, and when the voltage conversion module is in the first working state, the first voltage conversion unit is connected to the negative terminal of the DC side, and the second voltage conversion unit is connected to the positive terminal of the DC side; The voltage conversion module is configured to input electrical energy on the AC side. When the voltage conversion module is in the first working state, the first voltage conversion unit is connected to the positive terminal of the DC side, and the second voltage conversion unit is connected to the negative terminal of the DC side.

4. The battery management circuit according to claim 1, characterized in that, The voltage conversion module also has a third operating state, in which the voltage conversion module is configured such that, in the third operating state, some of the voltage conversion units are connected in parallel and some of the voltage conversion units are connected in series. The first control module is also used to adjust the voltage conversion module to the third working state according to the power signal on the AC side or the external control signal.

5. The battery management circuit according to claim 1, characterized in that, The battery management circuit further includes multiple second control modules, each corresponding to one of the voltage conversion units. The second control modules are used to receive and respond to the drive signals of the first control module to adjust the connection relationship between the voltage conversion unit and another adjacent voltage conversion unit, thereby switching the voltage conversion module to different working states.

6. The battery management circuit according to claim 5, characterized in that, The voltage conversion unit includes: The positive electrode wire has one end connected to the positive terminal of the battery and the other end connected to the positive terminal of the DC side. The negative terminal wire has one end connected to the negative terminal of the battery and the other end connected to the negative terminal of the DC side. The first capacitor has one end connected to the positive line and the other end connected to the negative line; A first power switch is disposed on the positive line or the negative line and is used to control the on / off state of the positive line; The second power switch is disposed between the positive line and the negative line, and is connected in series with another voltage conversion unit through the negative line. The second power switch is used to control the on / off state between the positive line and the negative line. The third power switch is connected at one end to the positive line and at the other end to another voltage conversion unit in parallel. The third power switch is configured to adjust the on / off state of the two ends of the third power switch under the control of the first control module.

7. The battery management circuit according to claim 6, characterized in that, The voltage conversion unit further includes a first inductor, which is disposed on the positive line or the negative line; At least two first power switching transistors are provided, and at least two first power switching transistors are connected in series on the positive line or the negative line; or at least one first power switching transistor is provided on the positive line and at least one first power switching transistor is provided on the negative line. And / or, the number of the first capacitors is at least two, and at least two of the first capacitors are connected in parallel between the positive line and the negative line; And / or, at least two second power switches are provided, and at least two second power switches are connected in parallel between the positive line and the negative line.

8. The battery management circuit according to claim 7, characterized in that, The voltage conversion unit also includes a fourth power switch; The first inductor and at least one first power switch are both disposed on the positive line, and the fourth power switch is disposed at the end of the first inductor away from the first power switch. Alternatively, the first inductor and at least one of the first power switches are disposed on the negative line, and the fourth power switch is disposed at the end of the first inductor away from the first power switch.

9. The battery management circuit according to any one of claims 1 to 8, characterized in that, The voltage conversion circuit includes a first converter and a second converter, the first converter being connected to the battery and the second converter being connected to the power frequency commutation module; The first converter is used to invert the first DC current output by the battery into a first AC current; the second converter 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 power frequency commutation module. Alternatively, the second converter is used to invert the third DC current output by the power frequency commutation module into a third AC current, and the first converter 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.

10. An energy storage system, characterized in that, The energy storage system includes a plurality of batteries and a battery management circuit as described in any one of claims 1 to 9, wherein the battery management circuit is used to manage the plurality of batteries.

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