Voltage conversion device, energy storage power supply, energy storage system and parallel operation control method

Abstract

The invention discloses a voltage conversion device, an energy storage power supply, an energy storage system and a parallel operation control method, and is applied to the technical field of energy storage. The voltage conversion device comprises at least one voltage conversion circuit, the first end of the voltage conversion circuit is configured to be connected with the energy storage power supply, the second end of the voltage conversion circuit is configured to be connected with the expansion battery packs, and the first controller is configured to adjust the duty ratio of the switch so that the main battery pack and the expansion battery packs can be in parallel operation; the first controller is further configured to obtain the charging and discharging power of the expanded battery pack under the charging and discharging condition of the expanded battery pack, and then the switch duty ratio of the voltage conversion circuit corresponding to the expanded battery pack is adjusted. The output voltage and the charging and discharging power of the extended battery pack are adjusted by adjusting the switch duty ratio of the voltage conversion circuit, so that parallel operation and power distribution of the energy storage power supply and the extended battery pack are realized, the problem of circulating current can be avoided, and the overall reliability and the energy utilization rate are improved.

Description

Technical Field

[0001] The present application belongs to the field of energy storage technology, and in particular relates to a voltage conversion device, an energy storage power supply, an energy storage system, and a parallel control method. Background Art

[0002] Energy storage systems play a vital role in modern society. They are widely used in production and daily life, storing electricity when prices are low and supplying power to loads when prices are high, thus reducing electricity costs. In particular, energy storage systems can serve as emergency power sources to maintain the operation of lighting, production equipment, and other equipment during power outages, ensuring that production and daily life are not disrupted.

[0003] As electricity demand grows, energy storage systems incorporate power supplies and expansion battery packs in parallel, increasing their capacity and efficiency. However, as science and technology advance, the performance of power supplies and expansion battery packs continues to improve, leading to corresponding increases in their rated voltages.

[0004] For users who have previously had energy storage power supplies and extension battery packs with lower rated voltages, if they only replace the energy storage power supply and use the extension battery pack with the replaced energy storage power supply with higher rated voltage in parallel, circulation problems may occur, causing energy loss and equipment heating, increasing the aging of the energy storage power supply and extension battery pack, and easily causing safety line failures, seriously affecting the service life of the energy storage power supply and extension battery pack, resulting in a decline in user experience and damage to the user's economic property. Summary of the Invention

[0005] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a voltage conversion device, an energy storage power supply, an energy storage system, and a parallel control method that can achieve parallel operation and power distribution between the energy storage power supply and an expansion battery pack, avoid circulating current problems, and improve overall reliability and energy utilization.

[0006] In a first aspect, the present application provides a voltage conversion device, comprising:

[0007] at least one voltage conversion circuit, wherein a first end of the voltage conversion circuit is configured to be connected to an energy storage power supply, wherein the energy storage power supply has a main battery pack disposed therein, and a second end of the voltage conversion circuit is configured to be connected to an extended battery pack;

[0008] A first controller is configured to communicate with the energy storage power source to obtain the voltage of the main battery pack and to communicate with the extended battery pack to obtain the voltage of the extended battery pack. The first controller is configured to adjust the switch duty cycle to match the voltage of the main battery pack with that of the extended battery pack so that the main battery pack and each of the extended battery packs are connected in parallel.

[0009] When the extended battery pack is discharging, the first controller is configured to obtain the discharge power of the extended battery pack and adjust the switch duty cycle of the voltage conversion circuit corresponding to the extended battery pack based on the discharge power;

[0010] When the extended battery pack is charged, the first controller is configured to obtain the charging power of the extended battery pack and adjust the switching duty cycle of the voltage conversion circuit corresponding to the extended battery pack based on the charging power.

[0011] In a second aspect, the present application provides an energy storage power supply, comprising:

[0012] Main battery pack;

[0013] A parallel interface, the parallel interface being configured to connect to the voltage conversion device according to claim 1 or 2 for parallel operation, and the parallel interface being further configured to connect to a DC power load;

[0014] AC power supply interface, the output end of which is configured to connect to an AC power load

[0015] An inverter module, wherein the input end of the inverter module is connected to the parallel interface, and the output end of the inverter module is connected to the input end of the AC power supply interface;

[0016] A second controller is connected to the main battery pack to obtain the voltage of the main battery pack, and the second controller is configured to communicate with the first controller of the voltage conversion device.

[0017] In a third aspect, the present application provides an energy storage system, comprising:

[0018] The above-mentioned voltage conversion device and energy storage power supply;

[0019] At least one extended battery pack, the energy storage power supply is connected in parallel with each of the extended battery packs through the voltage conversion device.

[0020] In a fourth aspect, the present application provides a parallel control method, which is applied to the above-mentioned voltage conversion device or the above-mentioned energy storage system. The parallel control method includes:

[0021] Obtaining the voltage of the main battery pack and each of the extended battery packs;

[0022] The switch duty cycle of the voltage conversion circuit connecting the main battery pack and any one of the extended battery packs is adjusted so that the voltage of the main battery pack matches the voltage of any one of the extended battery packs.

[0023] The voltage conversion device, energy storage power supply, energy storage system, and parallel control method provided in the embodiments of the present application adjust the output voltage of the extended battery pack by adjusting the switching duty cycle of the voltage conversion circuit. This ensures that the output voltage of the extended battery pack matches the voltage of the main battery pack after passing through the voltage conversion circuit, thereby achieving parallel operation. This prevents voltage differences between the main and extended battery packs, preventing abnormal current flow, or circulating current, thereby reducing energy waste, extending the service life of the main and extended battery packs, and improving overall reliability.

[0024] Moreover, when the extended battery pack is charging and discharging, by controlling the switching duty cycle of the battery conversion circuit corresponding to the extended battery pack, the charging and discharging power of the extended battery pack can be adjusted accordingly, thereby realizing power distribution between the energy storage power supply and the extended battery pack and improving the overall charging and discharging efficiency and energy utilization.

[0025] Additional aspects and advantages of the embodiments of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0027] Figure 1 is a schematic structural diagram of a voltage conversion device provided in an embodiment of the present application;

[0028] Figure 2 This is a schematic diagram of the structure of the energy storage power supply provided in an embodiment of the present application;

[0029] Figure 3 is a structural diagram of the energy storage system provided in an embodiment of the present application;

[0030] Figure 4 This is a first flow chart of the parallel control method provided in an embodiment of the present application;

[0031] Figure 5 This is a second flow chart of the parallel control method provided in an embodiment of the present application;

[0032] Figure 6 This is a third flow chart of the parallel control method provided in an embodiment of the present application;

[0033] Figure 7 This is a fourth flow chart of the parallel control method provided in an embodiment of the present application;

[0034] Figure 8 This is a fifth flow chart of the parallel control method provided in an embodiment of the present application;

[0035] Figure 9 This is a sixth flow chart of the parallel control method provided in an embodiment of the present application;

[0036] Figure 10 This is a seventh flow chart of the parallel control method provided in an embodiment of the present application;

[0037] Figure 11 Schematic diagram of the structure of the parallel control device provided in an embodiment of the present application;

[0038] Figure 12 It is a schematic diagram of the structure of the controller provided in an embodiment of the present application.

[0039] Description of reference numerals:

[0040] Voltage conversion device 100, voltage conversion circuit 10, first terminal 11, second terminal 12, first controller 20, energy storage power supply 200, main battery pack 210, parallel interface 220, AC power supply interface 230, inverter module 240, charging control circuit 250, discharge control circuit 260, second controller 270, energy storage system 300, extended battery pack 310, third controller 311, extended parallel interface 312. DETAILED DESCRIPTION

[0041] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and are not to be construed as limiting the present invention.

[0042] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0043] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, removable connections, or integral connections. They may refer to mechanical connections or electrical connections. They may refer to direct connections or indirect connections through an intermediary, and they may refer to internal communication between two components or interactions between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0044] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0045] See also Figure 1 , Figure 1 1 is a schematic diagram of the structure of a voltage conversion device 100 provided in an embodiment of the present application. The voltage conversion device 100 is described in detail below:

[0046] The voltage conversion device 100 includes at least one voltage conversion circuit 10 and a first controller 20. The first terminal 11 of the voltage conversion circuit 10 is configured to be connected to an energy storage power supply 200, which has a main battery pack 210 disposed therein. The second terminal 12 is configured to be connected to an extended battery pack 310.

[0047] The first controller 20 is configured to communicate with the energy storage power source 200 to obtain the voltage of the main battery pack 210, and to communicate with the extension battery pack 310 to obtain the voltage of the extension battery pack 310. The first controller 20 is configured to adjust the switching duty cycle of the voltage conversion circuit 10 to match the voltage of the main battery pack 210 with that of the extension battery pack 310, so that the main battery pack 210 and each extension battery pack 310 are connected in parallel;

[0048] When the extended battery pack 310 is discharging, the first controller 20 is configured to obtain the discharge power of the extended battery pack 310 and adjust the switch duty cycle of the voltage conversion circuit 10 corresponding to the extended battery pack 310 based on the discharge power;

[0049] When the extended battery pack 310 is charged, the first controller 20 is configured to obtain the charging power of the extended battery pack 310 and adjust the switching duty cycle of the voltage conversion circuit 10 corresponding to the extended battery pack 310 based on the charging power.

[0050] The voltage conversion circuit 10 includes multiple switching elements. By adjusting the duty cycle of each switching element, the output voltage of the extended battery pack 310 corresponding to the voltage conversion circuit 10 can be boosted or bucked. The voltage conversion circuit 10 can be an inductive boost circuit (referred to as a boost circuit), a charge pump boost circuit, a flyback boost circuit, etc., and this embodiment of the application is not limited to this.

[0051] The number of the voltage conversion circuit 10 can be one or more. Figure 1 In the example, there are 3. If there is enough space, the number of voltage conversion circuits 10 can also be 4, 5, etc., which is not limited in the embodiment of the present application.

[0052] Among them, the second end 12 of each voltage conversion circuit 10 can be connected to multiple extended battery packs 310 with the same specifications (such as rated voltage, battery capacity, charge and discharge characteristics, etc.). The second end 12 of each voltage conversion circuit 10 can be connected to one or more extended battery packs 310 as needed, and the embodiments of the present application do not limit this.

[0053] The first controller 20 is electrically connected to each voltage conversion circuit 10 , so that the controller can adjust the switching duty cycle of each or part of the voltage conversion circuit 10 according to demand.

[0054] Optionally, the first controller 20 may be a single chip microcomputer controller, a programmable logic controller (ie, a PLC controller), etc., which is not limited in the embodiment of the present application.

[0055] The first controller 20 is further configured to communicate with the energy storage power supply 200 to obtain the voltage of the main battery pack 210 in the energy storage power supply 200 , and to communicate with the extended battery pack 310 to obtain the voltage of the extended battery pack 310 .

[0056] The first controller 20 can also obtain information such as the current and output power of the main battery pack 210. Similarly, the first controller 20 can also obtain information such as the current and output power of the extended battery pack 310. Similarly, the energy storage power supply 200 and the extended battery pack 310 can also obtain information such as the input voltage and input current of each first terminal 11 and the output voltage and output current of each second terminal 12 of the voltage conversion device 100.

[0057] Optionally, the communication between the first controller 20 and the energy storage power supply 200, and the communication between the first controller 20 and the extended battery pack 310 can be achieved through communication lines (such as CAN bus, RS-485 bus, etc.) or wireless communications (such as Wi-Fi, Bluetooth, etc.).

[0058] In some embodiments, voltage matching between the main battery pack 210 and the extended battery pack 310 includes the voltages of the main battery pack 210 and the extended battery pack 310 being equal, or the voltage difference between the main battery pack 210 and the extended battery pack 310 being within a preset error range. The preset error range is a numerical range set based on experience.

[0059] In this way, the problem of circulating current between the main battery pack 210 and the extended battery pack 310 can be avoided, thereby improving safety.

[0060] See also Figure 2 , Figure 2 : This is a structural diagram of an energy storage power supply 200 provided in an embodiment of the present application. The energy storage power supply 200 is described in detail below:

[0061] The energy storage power supply 200 includes a main battery pack 210 , a parallel interface 220 , an AC power supply interface 230 , an inverter module 240 and a second controller 270 .

[0062] The parallel interface 220 of the energy storage power supply 200 is connected to the voltage conversion device 100 for parallel operation.

[0063] The parallel interface 220 has certain physical protection (such as waterproofing, dustproofing, and corrosion resistance) and communication layer protection (such as electromagnetic shielding). The parallel interface 220 is connected to the voltage conversion device 100 via a parallel cable. Optionally, the parallel cable can be a communication cable such as a CAN bus, RS-485 bus, Ethernet, etc., which is not limited in this embodiment of the present application.

[0064] The main battery pack 210 is connected to the parallel interface 220 , and the parallel interface 220 is also configured to connect to a DC power load.

[0065] The main battery pack 210 is a battery unit assembly composed of multiple single cells connected in series, parallel, or in a hybrid manner. The main battery pack 210 can output a stable voltage to the parallel interface 220 to supply power to the DC load.

[0066] Optionally, the main battery pack 210 may be a lithium-ion battery pack, a nickel-metal hydride battery pack, a lead-acid battery pack, etc., which is not limited in this embodiment of the present application.

[0067] The input of inverter module 240 is connected to parallel interface 220, and its output is connected to the input of AC power interface 230. The output of AC power interface 230 is configured to connect to an AC load. Inverter module 240 is used to convert the DC power from parallel interface 220 into AC power. The DC power output from main battery pack 210 can be used to power external AC loads through inverter module 240 and AC power interface 230. This improves the power supply flexibility of energy storage power supply 200.

[0068] Optionally, the inverter module 240 may be a full-bridge inverter, a half-bridge inverter, a push-pull inverter, etc., which is not limited in the embodiment of the present application.

[0069] Among them, the charging control circuit 250 is connected to the main battery pack 210 and the parallel interface 220, and the charging control circuit 250 is also connected to the main battery pack 210 and the inverter module 240; the discharging control circuit 250 is connected to the main battery pack 210 and the parallel interface 220, and the discharging control circuit 250 is also connected to the main battery pack 210 and the inverter module 240.

[0070] The charging control circuit 250 is used to control the on / off state of the charging process of the energy storage power supply 200, and the discharging control circuit 250 is used to control the on / off state of the discharging process of the energy storage power supply 200. Optionally, the charging control circuit 250 and the discharging control circuit 250 can be control circuits based on MOS tubes, using metal-oxide-semiconductor field-effect transistors (i.e., MOSFETs) as switching elements, and controlling the on / off state of the MOSFETs by controlling the gate voltage of the MOSFETs, thereby controlling the charging and discharging of the battery pack. The charging control circuit 250 and the discharging control circuit 250 can also be other types of control circuits, which are not limited in the embodiments of the present application.

[0071] The second controller 270 is connected to the first controller 20 of the voltage conversion device 100 for communication to obtain voltage and other information of the voltage conversion device 100 collected by the first controller 20 , or to send voltage, current and other information of the main battery pack 210 to the first controller 20 .

[0072] The second controller 270 is further configured to control the operating conditions of the inverter module 240, the charging control circuit 250, and the discharging control circuit 250 to ensure normal charging and discharging of the energy storage power supply 200. Alternatively, the second controller 270 may be a single-chip microcomputer controller, a programmable logic controller (i.e., a PLC controller), etc., which is not limited in this embodiment of the present application.

[0073] See also Figure 3 , Figure 3 : is a schematic diagram of the structure of an energy storage system 300 provided in an embodiment of the present application. The energy storage system 300 is described in detail below:

[0074] The energy storage system 300 includes the aforementioned voltage conversion device 100 , the aforementioned energy storage power supply 200 , and at least one extended battery pack 310 .

[0075] The energy storage power supply 200 and the extended battery pack 310 are connected in parallel through the voltage conversion device 100, which can improve the power capacity and output power of the energy storage system 300, enhance the reliability of the energy storage system 300, and improve the flexibility and scalability of the energy storage system 300.

[0076] The expansion battery pack 310 includes a third controller 311 and an expansion parallel interface 312. The third controller 311 can obtain information such as the voltage of the expansion battery pack 310 and communicate with the first controller 20. The expansion parallel interface has certain physical protection (such as waterproofing, dustproofing, and corrosion resistance) and communication layer protection (such as electromagnetic shielding). The expansion battery pack 310 is connected to the corresponding voltage conversion circuit 10 in the voltage conversion device 100 via the expansion parallel interface 312 and the parallel cable.

[0077] Optionally, the third controller may be a single chip microcomputer controller, a programmable logic controller (ie, a PLC controller), etc., which is not limited in the embodiment of the present application.

[0078] The specifications of the expansion battery packs 310 can be different, for example, with rated voltages of 55V and 110V respectively. These two expansion battery packs 310 can be connected to different voltage conversion circuits 10 in the voltage conversion device 100, and then connected in parallel with the energy storage power supply 200. This can effectively improve the flexibility and scalability of the energy storage system 300.

[0079] Connecting each expansion battery pack 310 in parallel with the energy storage power supply 200 via the voltage conversion device 100 clarifies primary and secondary functions, simplifying parallel management. Increasing or decreasing the number of expansion battery packs 310 does not affect the operation of the energy storage power supply 200, thus adapting to power demands in various situations. Furthermore, connecting external loads primarily through the energy storage power supply 200 avoids excessive load connections and improves the reliability of the energy storage system 300.

[0080] Based on the introduction of the above voltage conversion device, energy storage power supply, and energy storage system, the embodiment of the present application provides a parallel control method, which is applied to the above voltage conversion device or the above energy storage system. The parallel control method is described in detail below:

[0081] See also Figure 4 A parallel control method provided in an embodiment of the present application is implemented by steps 011 and 012, which are described in detail below.

[0082] Step 011: Obtain the voltage of the main battery pack and each extended battery pack;

[0083] Step 012: Adjust the switch duty cycle of the voltage conversion circuit connecting the main battery pack and any extended battery pack so that the voltage of the main battery pack matches the voltage of any extended battery pack.

[0084] Specifically, the first controller, the second controller and each third controller communicate with each other, the second controller can obtain the output voltage of the main battery pack in real time, and each third controller can obtain the output voltage of the corresponding extended battery pack in real time.

[0085] When any voltage conversion circuit is connected to an extended battery pack, the output voltage of the corresponding extended battery pack can be boosted or bucked (primarily boosted) by adjusting the switching duty cycle of the voltage conversion circuit so that the output voltage of the voltage conversion circuit matches the output voltage of the main battery pack. That is, the output voltage of the voltage conversion circuit is equal to the output voltage of the main battery pack, or the voltage difference between the output voltage of the voltage conversion circuit and the output voltage of the main battery pack is within a preset error range. The preset error range is a numerical range determined based on experience.

[0086] In this way, each extended battery pack can work synchronously with the main battery pack, avoiding power transmission problems caused by circulation problems and voltage mismatch, and improving the safety and reliability of the charging and discharging process.

[0087] In some embodiments, see Figure 5 The parallel control method further includes step 013, which is described in detail below.

[0088] Step 013: When the voltage conversion device is connected to other extended battery packs, adjust the switch duty cycle of the target voltage conversion circuit between the main battery pack and the connected extended battery pack so that the change trend of the output voltage of the target voltage conversion circuit meets the preset voltage change trend.

[0089] The target voltage conversion circuit refers to the voltage conversion circuit corresponding to the newly connected expansion battery pack of the voltage conversion device. There can be one or more target voltage conversion circuits.

[0090] Among them, the preset voltage change trend includes the output voltage increasing at a preset voltage change rate, or increasing to a target voltage within a preset time period, and the target voltage is determined based on the voltage of the main battery pack (the target voltage is equal to the output voltage of the main battery pack, or the voltage difference between the target voltage and the main battery pack is within a preset difference range).

[0091] Specifically, when one or more expansion battery packs are newly connected to the voltage conversion device, the output voltage of the expansion battery pack after passing through the target voltage conversion circuit may differ significantly from the output voltage of the main battery pack. This can cause a sudden high current surge, potentially damaging the energy storage power supply, the voltage conversion device, and the expansion battery pack, reducing its service life. Therefore, a soft-start strategy is adopted to slowly power up the expansion battery pack, thereby avoiding sudden high current surges and improving the reliability of the energy storage system.

[0092] The soft start strategy includes adjusting the switch duty cycle of the target voltage conversion circuit so that the change trend of the output voltage of the target voltage conversion circuit meets the preset voltage change trend.

[0093] By setting an initial switching duty cycle (low value) for the target voltage conversion circuit, the initial output voltage of the target voltage conversion circuit is low, thereby avoiding the generation of large current surges. The change rate of the switching duty cycle of the corresponding target voltage conversion circuit is calculated based on the preset voltage change rate. The switching duty cycle value is gradually increased based on the change rate of the switching duty cycle of the corresponding target voltage conversion circuit, so that the output voltage of the target voltage conversion circuit gradually increases to the target voltage at the preset voltage change rate.

[0094] Optionally, when the difference between the output voltage of the target voltage conversion circuit and the output voltage of the main battery pack is less than a preset difference, the switching duty cycle of the target voltage conversion circuit is adjusted so that the output voltage of the target voltage conversion circuit increases at a rate less than a preset voltage change rate (e.g., half or one-quarter of the preset voltage change rate), so that the output voltage of the target voltage conversion circuit smoothly approaches the target voltage. The preset difference is a value set based on experience.

[0095] Alternatively, a proportional-integral-differential control algorithm (i.e., a PID control algorithm) may be used to continuously calculate the difference between the output voltage and the target voltage, and based on a preset difference range within which the difference lies, the switching duty cycle of the target voltage conversion circuit may be adjusted so that the output voltage of the target voltage conversion circuit gradually increases to the target voltage. For example, when the difference lies within a first preset difference range, the switching duty cycle of the target voltage conversion circuit may be increased based on a rate of change corresponding to the first preset difference range.

[0096] Optionally, by controlling the switching duty cycle of the target voltage conversion circuit, the output voltage of the target voltage conversion circuit is increased at an appropriate initial voltage rise rate within a preset time period, and the voltage rise rate is gradually reduced, so that the output voltage of the target voltage conversion circuit is gradually increased to the target voltage.

[0097] For example, the switching duty cycle of the target voltage conversion circuit can be adjusted first so that the output voltage of the target voltage conversion circuit increases at a rate of 1.5 times the preset voltage change rate; when the output voltage of the target voltage conversion circuit rises to half of the target voltage, the switching duty cycle of the target voltage conversion circuit can be adjusted again so that the output voltage of the target voltage conversion circuit increases at a preset voltage change rate; when the output voltage of the target voltage conversion circuit rises to 90% of the target voltage, the switching duty cycle of the target voltage conversion circuit can be adjusted again so that the output voltage of the target voltage conversion circuit increases to the target voltage at a rate of 0.25 times the preset voltage change rate.

[0098] In some embodiments, see Figure 6 The parallel control method further includes step 014, which is described in detail below.

[0099] Step 014: When the charge and discharge mode of the main battery pack is switched, the switching duty cycle of each voltage conversion circuit is adjusted so that the variation trend of the output voltage of each voltage conversion circuit meets the preset voltage variation trend.

[0100] When the main battery pack's charge / discharge mode is switched, the charge distribution on the electrode surfaces of the main and extended battery packs needs to be readjusted, potentially causing a sudden surge in current. This can accelerate aging and reduce the service life of the main and extended battery packs. Therefore, when the main battery pack's charge / discharge mode is switched, the output voltage of each voltage conversion circuit must be increased from a smaller value to the target voltage to meet the preset voltage change trend.

[0101] The specific process of adjusting the switch duty cycle of each voltage conversion circuit is similar to the case where the above-mentioned voltage conversion device is connected to other extended battery packs. To avoid repetition, it will not be repeated here.

[0102] In some embodiments, see Figure 7 The parallel control method also includes step 015, which is described in detail below.

[0103] Step 015: When the charge / discharge mode of the main battery pack is switched, adjusting the switching duty cycle of each voltage conversion circuit so that the output current variation trend of each voltage conversion circuit meets the preset current variation trend;

[0104] The preset current change trend includes the output current increasing to a target current within a preset current conversion speed range, and the target current is determined based on the rated current of the extended battery pack.

[0105] Specifically, when the charge and discharge modes of the main battery pack are switched, it is necessary to prevent the output current of each voltage conversion circuit from exceeding the current safety threshold or causing a current surge, thereby avoiding causing safety problems.

[0106] Optionally, when a sudden increase in current is detected (i.e., the rate of change of current is greater than a preset current change rate), the switching duty cycle of the voltage conversion circuit is temporarily stopped or slowed down until the output current returns to the set safe current range and no longer suddenly increases, and the switching duty cycle of the voltage conversion circuit is continued to be increased so that the output current reaches the target current.

[0107] Optionally, when a sudden current surge is detected and the switching duty cycle of the voltage conversion circuit is temporarily stopped or slowed down, if the current continues to surge or the current value continues to exceed the current safety threshold, it is determined that an abnormal condition has occurred and the voltage conversion circuit is cut off to protect the safety of related equipment.

[0108] Similarly, when a new expansion battery pack (i.e., a target expansion battery pack) is connected to the voltage conversion device, the switching duty cycle of the target voltage conversion circuit needs to be adjusted so that the output current variation trend of the target voltage conversion circuit meets the preset current variation trend. This can avoid the occurrence of instantaneous high current and improve overall reliability.

[0109] In some embodiments, see Figure 8 , step 012 includes:

[0110] Step 0121: determining adjustment parameters of the voltage conversion circuit based on a voltage difference between the real-time voltage of the main battery pack and the real-time voltage of the voltage conversion circuit corresponding to any extended battery pack;

[0111] Step 0122: Adjust the switch duty cycle of the voltage conversion circuit based on the adjustment parameter so that the real-time voltage of the main battery pack matches the real-time voltage of the voltage conversion circuit corresponding to any extended battery pack.

[0112] The adjustment parameter refers to a parameter generated based on the voltage difference using a control algorithm (such as a PID control algorithm) for adjusting the switching duty cycle of the voltage conversion circuit. The adjustment parameter includes an adjustment direction and an adjustment step size.

[0113] Among them, the real-time voltage of the main battery pack matches the real-time voltage of the voltage conversion circuit corresponding to any extended battery pack, which means that the real-time voltage of the main battery pack is equal to the real-time voltage of any extended battery pack after passing through the corresponding voltage conversion circuit, or the voltage difference between the two is within a preset difference range, where the preset difference range is a numerical range set based on experience.

[0114] Specifically, the real-time voltages of the voltage conversion circuits corresponding to the main battery pack and any extended battery pack are obtained, and the voltage difference between the two is calculated. The real-time voltage of the main battery pack, the real-time voltage of the voltage conversion circuit corresponding to any extended battery pack, and the voltage difference between the two satisfy the relationship expressed in equation (1).

[0115] V error =V main -V ext,i (1)

[0116] Among them, V main Indicates the real-time voltage of the main battery pack, V ext,i represents the real-time voltage of the voltage conversion circuit corresponding to the i-th extended battery pack, where i represents the i-th extended battery pack in the order of all extended battery packs; V error Indicates the voltage difference between the two.

[0117] According to the PID control algorithm (or other types of control algorithms, etc.), the voltage difference V error As a reference input, the corresponding adjustment parameter is generated, and the switch duty cycle of the voltage conversion circuit is adjusted based on the adjustment parameter to form a closed-loop feedback so that the voltage difference V error Gradually becomes zero, achieving voltage following and improving overall reliability.

[0118] Optionally, voltage following can also be achieved by controlling the voltage adjustment coefficient. Specifically, the real-time voltage value of the voltage conversion circuit corresponding to the i-th extended battery pack satisfies the relationship expressed in formula (2).

[0119] V ext,i =V main -K v ·(V main -V nom,i ) (2)

[0120] Among them, V ext,i represents the real-time voltage of the voltage conversion circuit corresponding to the i-th extended battery pack, where i represents the i-th extended battery pack in the order of all extended battery packs; V main Indicates the real-time voltage of the main battery pack, K v Indicates the voltage adjustment coefficient, V nom,i Indicates the rated voltage of the i-th extended battery pack.

[0121] By continuously and appropriately reducing the value of the voltage adjustment coefficient, the final voltage adjustment coefficient is made zero (or close to zero), so that the real-time voltage of the voltage conversion circuit corresponding to the i-th extended battery pack matches the real-time voltage of the main battery pack.

[0122] Optionally, adjustment parameters of each voltage conversion circuit may be determined based on the voltage difference between the real-time voltage of the main battery pack and the real-time voltage of each extended battery pack, so that the real-time voltages of the main battery pack and each extended battery pack match, thereby improving overall reliability.

[0123] In some embodiments, see Figure 9 The parallel control method also includes step 016 and step 017, which are described in detail below.

[0124] Step 016: Determine the discharge power of each extended battery pack based on the operating parameters of each extended battery pack;

[0125] Step 017: Based on the discharge power of each extended battery pack, adjust the switch duty cycle of the voltage conversion circuit corresponding to each extended battery pack.

[0126] The operating parameters refer to operating parameters of the extended battery pack when in operation. The operating parameters include at least one of the remaining capacity, rated voltage, and remaining discharge current, wherein the remaining discharge current is determined based on the current discharge current and maximum discharge current of the extended battery pack;

[0127] Specifically, based on the operating parameters of each expansion battery pack, the corresponding weight factor related to discharge power is determined. Based on the ratio of each expansion battery pack's weight factor to the total weight factor of all expansion battery packs, the corresponding discharge power is allocated. Then, the switching duty cycle of the voltage conversion circuit corresponding to the expansion battery pack is adjusted accordingly, so that the corresponding expansion battery pack outputs the corresponding discharge power, and ultimately the energy storage system outputs the required total output power. This can improve the power supply capacity and reliability of the energy storage system.

[0128] The output capacity of the extended battery pack is strongly correlated with the current remaining power, voltage, and current. Therefore, the weight factor of the extended battery pack can be set to satisfy the relationship expressed in formula (3), and the weight factor can be calculated.

[0129] ω i =k1·SOC i ·F V,i +k2·C i (3)

[0130] Among them, ω i represents the weight factor of the i-th extended battery pack, k1 represents the first empirical coefficient, k2 represents the second empirical coefficient, the first empirical coefficient and the second empirical coefficient are preset values ​​based on experience or experimental calibration; SOC i Indicates the current remaining power of the i-th extended battery pack, F V,i represents the voltage matching factor of the i-th extended battery pack, C iRepresents the discharge capacity factor of the i-th extended battery pack.

[0131] Wherein, i is a positive integer not greater than N, N is the number of extended battery packs, and N is a positive integer.

[0132] The voltage matching factor of the extended battery pack satisfies the relationship expressed in formula (4):

[0133]

[0134] Among them, F V,i Represents the voltage matching factor of the i-th extended battery pack, V rated,i Indicates the rated voltage of the i-th extended battery pack, V main Indicates the rated voltage of the main battery pack. A higher rated voltage of an extended battery pack indicates a stronger output capability, allowing for more output power to be allocated, improving overall power supply performance.

[0135] The discharge capacity factor satisfies the relationship expressed in formula (5):

[0136]

[0137] Among them, C i Represents the discharge capacity factor of the i-th extended battery pack, I max,i Indicates the maximum discharge current of the i-th extended battery pack, I current,i Indicates the current discharge current of the i-th extended battery pack, V main Indicates the rated voltage of the main battery pack. The maximum discharge current minus the current discharge current indicates the remaining discharge capacity of the expansion battery pack. Allocating more output power to expansion battery packs with greater remaining discharge capacity can improve the stability and reliability of the energy storage system.

[0138] According to the ratio of the weight factor of each extended battery pack to the total weight factor of all extended battery packs, the corresponding discharge power is allocated, and the output power of the extended battery pack satisfies the relationship expressed in formula (6):

[0139]

[0140] Among them, P alloc,i represents the output power of the i-th extended battery pack, η i represents the conversion efficiency of the voltage conversion circuit corresponding to the i-th extended battery pack, P total Express the total output power delivered to the load, ω i represents the weight factor of the i-th extended battery pack, and N represents the number of extended battery packs (N is a positive integer).

[0141] Among them, η iThe conversion efficiency indicates the ratio between the output power and the input power of the voltage conversion circuit corresponding to the i-th extended battery pack, and the value range is (0,1). In order to meet the power demand and ensure the total output power, each extended battery pack needs to output more discharge power. Under different working conditions of the voltage conversion circuit, the conversion efficiency can be obtained by querying the conversion efficiency data under the corresponding working conditions in the specification of the voltage conversion circuit, or by setting the corresponding working conditions in the simulation software. The conversion efficiency under the corresponding working conditions can also be obtained by other means, which is not limited in the embodiments of the present application.

[0142] The output current of the extended battery pack satisfies the relationship expressed in equation (7):

[0143]

[0144] Among them, I out,i Represents the output current of the i-th extended battery pack, P alloc,i Represents the output power of the i-th extended battery pack, V i Indicates the real-time output voltage of the i-th extended battery pack.

[0145] Optionally, a current protection threshold is set in the extended battery pack, and the value of the current protection threshold is the output current I out,i Add a preset fluctuating current value, where the preset fluctuating current value is a value set based on experience. If the output current of the extended battery pack exceeds the corresponding current protection threshold, the output of the extended battery pack is disconnected to protect the safety of related equipment in the energy storage system.

[0146] In some embodiments, see Figure 10 The parallel control method also includes steps 018 and 019, which are described in detail below.

[0147] Step 018: Determine the charging power of each extended battery pack based on the operating parameters of each extended battery pack, where the operating parameters include at least one of the remaining power (i.e., the current remaining power) and the rated voltage;

[0148] Step 019: Based on the charging power of each extended battery pack, adjust the switch duty cycle of the voltage conversion circuit corresponding to each extended battery pack.

[0149] Specifically, the charging power is determined based on the operating parameters of the extended battery pack, and the charging current is allocated based on the proportion of the charging power in the total charging power. When charging each extended battery pack, a constant current charging strategy is adopted to control the switching duty cycle of each voltage conversion circuit so that the output current of each voltage conversion circuit is the corresponding allocated current. This can avoid the impact of excessive current on the equipment, improve charging efficiency, and simplify charging control, making it easy to monitor and manage.

[0150] The charging current of the extended battery pack satisfies the relationship expressed in equation (8):

[0151]

[0152] Among them, I charge,i Indicates the charging current corresponding to the i-th extended battery pack; K cc Represents the charge control gain coefficient. The charge control gain coefficient is a preset value based on experimental calibration. Under different working conditions (such as different battery properties, different remaining power, and different temperatures), the value of the charge control gain coefficient varies and can be obtained based on the calibration conditions. ref Describes the target charging voltage (describes the battery voltage when the extended battery pack is fully charged, based on the rated voltage setting), V ext,i Indicates the current output voltage of the i-th extended battery pack, SOC max Indicates the maximum remaining power, SOC i Indicates the current remaining power of the i-th extended battery pack.

[0153] When the remaining charge of an expansion battery pack is low, indicating a greater need for charging, a higher charging power and current are allocated to quickly replenish the remaining charge. When the remaining charge of an expansion battery pack is high, a lower charging power and current are allocated to avoid overcharging the expansion battery pack. This gradually brings the remaining charge of each expansion battery pack closer together, enhancing the power supply performance, extending the service life, and improving the safety of the energy storage system.

[0154] According to the method described in the above embodiment, the present application also provides a parallel control device 400 for executing the steps in the above parallel control method. Figure 11 , Figure 11 : is a module diagram of a parallel control device 400 provided in an embodiment of the present application. The parallel control device 400 includes:

[0155] An acquisition module 401 is used to acquire the voltage of the main battery pack and each extended battery pack;

[0156] The adjustment module 402 is configured to adjust a switch duty cycle of a voltage conversion circuit connecting the main battery pack and any extended battery pack so that the voltage of the main battery pack matches the voltage of any extended battery pack.

[0157] It should be noted that the specific details of each module unit in the above-mentioned parallel control device have been described in detail in the embodiment of the above-mentioned parallel control method, and will not be repeated here.

[0158] In the embodiments of the present application, the term "module" or "unit" refers to a computer program or a part of a computer program that has a predetermined function and works together with other related parts to achieve a predetermined goal, and can be implemented in whole or in part by using software, hardware (such as processing circuits or memories) or a combination thereof. Similarly, a processor (or multiple processors or memories) can be used to implement one or more modules or units. In addition, each module or unit can be part of an overall module or unit that includes the function of the module or unit.

[0159] In some embodiments, the parallel control device in the embodiments of the present application can be implemented in hardware, such as a controller (such as the first controller in the voltage conversion device, and / or the second controller in the energy storage power supply, and / or the third controller in the extended battery pack), or a component in the controller, such as an integrated circuit or a chip; the parallel control device can also be implemented in software, such as as an application installed in the controller.

[0160] In some embodiments, see Figure 12 , Figure 12 is a schematic diagram of the structure of a controller provided in an embodiment of the present application. Controller 500 includes a processor 501 and a memory 502. Memory 502 stores a computer program 503 executable on processor 501. When executed by processor 501, program 503 implements the various processes of the aforementioned embodiment of the parallel control method and achieves the same technical effects. To avoid repetition, these are not described here.

[0161] An embodiment of the present application also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the various processes of the embodiment of the above-mentioned parallel control method are implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0162] The processor may be the processor in the controller in the above embodiment. The computer readable storage medium may be a computer read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0163] Computer-readable media may include computer storage media and communication media. Computer storage media include volatile and non-volatile, removable and non-removable media implemented by any method or technology for storing information such as computer-readable instructions, data structures, program modules or other data. Computer storage media include RAM, ROM, Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), flash memory or other solid-state memory technology, CD-ROM, Digital Versatile Disc (DVD) or other optical storage, tape cassettes, magnetic tape, disk storage or other magnetic storage devices. Of course, those skilled in the art will appreciate that computer storage media are not limited to the above.

[0164] The present application also provides a computer program product, including a computer program, which, when executed by a processor, implements the aforementioned parallel control method. The processor may be the processor in the controller described in the aforementioned embodiment. When executed by the processor, the computer program implements the various processes of the aforementioned parallel control method embodiment, achieving the same technical effects. To avoid repetition, these processes are not described here.

[0165] It is understandable that in the specific implementation of this application, data related to user identity or characteristics is involved. When the above embodiments of this application are applied to specific products or technologies, user permission or consent is required, and the collection, use and processing of relevant data must comply with relevant laws, regulations and standards of relevant countries and regions.

[0166] In the description of this specification, the reference terms "certain embodiments", "in an example", "exemplarily", etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are mutually inconsistent.

[0167] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and intent of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A voltage conversion device, characterized in that: include: at least one voltage conversion circuit, wherein a first end of the voltage conversion circuit is configured to be connected to an energy storage power supply, wherein the energy storage power supply has a main battery pack disposed therein, and a second end of the voltage conversion circuit is configured to be connected to an extended battery pack; a first controller configured to communicate with the energy storage power source to obtain the voltage of the main battery pack and to communicate with the extension battery pack to obtain the voltage of the extension battery pack, wherein the first controller is configured to adjust a switching duty cycle of the voltage conversion circuit to match the voltage of the main battery pack with that of the extension battery pack, so that the main battery pack and each of the extension battery packs are operated in parallel; When the extended battery pack is discharging, the first controller is configured to obtain the discharge power of the extended battery pack and adjust the switch duty cycle of the voltage conversion circuit corresponding to the extended battery pack based on the discharge power; When the extended battery pack is charged, the first controller is configured to obtain the charging power of the extended battery pack and adjust the switching duty cycle of the voltage conversion circuit corresponding to the extended battery pack based on the charging power.

2. The voltage conversion device according to claim 1, wherein: The voltage matching between the main battery pack and the extended battery pack includes that the voltages of the main battery pack and the extended battery pack are equal.

3. An energy storage power supply, characterized in that: include: Main battery pack; A parallel interface, the parallel interface being configured to connect to the voltage conversion device according to claim 1 or 2 for parallel operation, and the parallel interface being further configured to connect to a DC power load; AC power supply interface, the output end of which is configured to connect to an AC power load An inverter module, wherein the input end of the inverter module is connected to the parallel interface, and the output end of the inverter module is connected to the input end of the AC power supply interface; A second controller is connected to the main battery pack to obtain the voltage of the main battery pack, and the second controller is configured to communicate with the first controller of the voltage conversion device.

4. An energy storage system, characterized in that: include: The voltage conversion device according to claim 1 or 2; The energy storage power supply according to claim 3; At least one extended battery pack, the energy storage power supply is connected in parallel with each of the extended battery packs through the voltage conversion device.

5. A parallel control method, characterized in that: Applied to the voltage conversion device according to claim 1 or 2, or the energy storage system according to claim 4, the parallel control method includes: Obtaining the voltage of the main battery pack and each of the extended battery packs; The switch duty cycle of the voltage conversion circuit connecting the main battery pack and any one of the extended battery packs is adjusted so that the voltage of the main battery pack matches the voltage of any one of the extended battery packs.

6. The parallel control method according to claim 5, characterized in that: Also includes: When the voltage conversion device is connected to another extended battery pack, the switch duty cycle of the target voltage conversion circuit between the main battery pack and the connected extended battery pack is adjusted so that the change trend of the output voltage of the target voltage conversion circuit meets the preset voltage change trend.

7. The parallel control method according to claim 5, characterized in that: Also includes: When the charge and discharge mode of the main battery pack is switched, the switch duty cycle of each of the voltage conversion circuits is adjusted so that a variation trend of the output voltage of each of the voltage conversion circuits meets a preset voltage variation trend.

8. The parallel control method according to claim 6 or 7, characterized in that: The preset voltage change trend includes the output voltage increasing at a preset voltage change rate, or increasing incrementally to a target voltage within a preset time period, where the target voltage is determined based on the voltage of the main battery pack.

9. The parallel control method according to claim 5, characterized in that: Also includes: When the charge and discharge mode of the main battery pack is switched, adjusting the switching duty cycle of each of the voltage conversion circuits so that a change trend of the output current of each of the voltage conversion circuits satisfies a preset current change trend; The preset current change trend includes the output current increasing to a target current within a preset current conversion speed range, and the target current is determined based on the rated current of the extended battery pack.

10. The parallel control method according to claim 5, characterized in that: The adjusting the switch duty cycle of the voltage conversion circuit connecting the main battery pack and any one of the extended battery packs so that the voltage of the main battery pack matches the voltage of any one of the extended battery packs includes: determining an adjustment parameter of the voltage conversion circuit based on a voltage difference between the real-time voltage of the main battery pack and the real-time voltage of the voltage conversion circuit corresponding to any one of the extended battery packs; The switch duty cycle of the voltage conversion circuit is adjusted based on the adjustment parameter so that the real-time voltage of the main battery pack matches the real-time voltage of the voltage conversion circuit corresponding to any one of the extended battery packs.

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