Wide-voltage energy storage converter and use method

Abstract

The invention provides a wide-voltage energy storage converter and a using method thereof in the technical field of energy storage converters. The energy storage converter comprises an AC / DC module, an AC / DC converter, a DC / DC converter and an AC / DC converter, a DC / DC module; the AC side terminal A is connected with the pin A of the AC / DC module; the AC side terminal B is connected with a pin B of the AC / DC module; the AC side terminal C is connected with a pin C of the AC / DC module; a DC side terminal DC +; the direct current side terminal DC-is connected with a pin BUS-of the AC / DC module; one end of the switch KM1 is connected with a pin BUS + of the AC / DC module, and the other end of the switch KM1 is connected with the direct current side terminal DC +; one end of the switch KM2 is connected with a pin BUS + of the AC / DC module, and the other end of the switch KM2 is connected with a pin DC1 of the DC / DC module; and one end of the switch KM3 is connected with the pin DC2 of the DC / DC module, and the other end of the switch KM3 is connected with the direct current side terminal DC +. The invention has the advantages that zero-voltage starting and low-voltage constant-power output are realized at low cost, and wide-voltage operation capability is realized.

Description

Technical Field

[0001] This invention relates to the field of energy storage converter technology, and in particular to a wide-voltage energy storage converter and its usage method. Background Technology

[0002] A Power Conversion System (PCS), also known as an energy storage inverter or bidirectional converter, is a bidirectional controllable power conversion device that connects an energy storage battery system to the power grid (or load). It enables bidirectional conversion between direct current (DC) and alternating current (AC) and controls the charging and discharging process of the energy storage battery system. In charging mode, the PCS rectifies AC power from the grid or renewable energy sources into DC power and charges the battery. In discharging mode, it inverts the DC power released from the battery into AC power, feeding it back to the grid or supplying power to local loads. By adjusting parameters such as voltage, frequency, and power, the PCS can effectively smooth the fluctuating power output of renewable energy sources such as photovoltaics and wind power, achieving grid support functions such as peak shaving, valley filling, frequency regulation, and voltage regulation. Depending on the operating mode, PCS can be divided into grid-connected mode (interacting with the grid), off-grid mode (independently supplying power to loads), and hybrid mode (supporting grid-connected / off-grid switching) to improve system power supply reliability.

[0003] Applying precharge converters (PCS) to flow batteries presents unique technical challenges. Flow batteries (such as vanadium redox flow batteries) have a wide DC-side operating voltage range, and their initial state often requires charging and activation from zero voltage. Therefore, the PCS needs to have a wide voltage input capability and support zero-voltage start-up. Currently, a common approach is to connect a high-power precharge resistor in series or add a DC / DC converter stage to achieve zero-voltage precharge.

[0004] Furthermore, while the voltage of a flow battery increases with the number of cells connected in series, the problem of electrolyte leakage current also intensifies. The leakage current generation mechanism mainly involves two aspects: first, the electrolyte flows into the positive and negative electrodes of each individual cell through a common conduit, forming an ion conduction path; second, the individual cells connected in series in the stack form a voltage gradient and an electron conduction path. The ion and electron channels together form a closed loop, leading to leakage current. To reduce the impact of leakage current on system efficiency, the total voltage of the flow battery should generally not be too high; therefore, most manufacturers set its DC-side voltage below 500V or even 300V. However, traditional PCS (Power Conversion System) is limited by its topology, and its DC-side voltage must be higher than the rectified AC-side voltage. For example, when the AC-side voltage is 400VAC, the rectified DC voltage is approximately 565V. To meet the lower DC voltage requirements of flow batteries, the industry currently mainly adopts two solutions: one is to add a DC / DC step-down circuit on the DC side; the other is to add a transformer on the AC side for voltage reduction. However, both of these approaches limit the actual output power of high-power PCS, resulting in a significant increase in unit power cost.

[0005] When PCS is applied to supercapacitors, it faces more stringent voltage operation requirements. Supercapacitors can discharge down to 0V and need to maintain a high power level throughout the charging and discharging process. Therefore, PCS is required to have an extremely wide DC voltage adaptability range, with the minimum operating voltage close to 0V. Existing technologies mostly achieve voltage reduction through series DC / DC converters.

[0006] In summary, traditional PCS, limited by its circuit topology, requires the DC-side voltage to be √2 times higher than the AC-side voltage (i.e., the peak AC voltage), making direct step-down operation impossible. This results in significant limitations in meeting the zero-voltage start-up requirements and low-voltage operation range of flow batteries, as well as the 0V start-up and low-voltage constant-power operation required by supercapacitors. Existing technologies typically use a series DC / DC converter to support 0V start-up and low-voltage operation, but the DC / DC converter must withstand the same or even higher operating current as the AC / DC section, especially under low-voltage conditions where the required power capacity is greater, leading to high system costs. Alternatively, a pre-charge resistor can be used to achieve zero-voltage start-up, but in applications where flow batteries operate at low voltage for extended periods, the transformer turns ratio must be reduced to lower the PCS AC-side voltage, thereby reducing the minimum DC-side operating voltage. Since the PCS's maximum overcurrent capacity is fixed, voltage reduction directly leads to a significant decrease in its maximum output power, resulting in a sharp increase in the system's unit power cost.

[0007] Therefore, how to provide a wide-voltage energy storage converter and its usage method to achieve zero-voltage start-up, low-voltage constant power output and wide-voltage operation capability at low cost has become an urgent technical problem to be solved. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a wide voltage energy storage converter and its usage method, so as to achieve zero voltage start-up, low voltage constant power output and wide voltage operation capability at low cost.

[0009] In a first aspect, the present invention provides a wide-voltage energy storage converter, comprising: An AC / DC module; A DC / DC module; An AC-side terminal A is connected to pin A of the AC / DC module; An AC-side terminal B is connected to pin B of the AC / DC module; An AC side terminal C is connected to pin C of the AC / DC module; One DC-side terminal DC+; A DC- side terminal is connected to the BUS- pin of the AC / DC module; A switch KM1 has one end connected to the BUS+ pin of the AC / DC module and the other end connected to the DC+ terminal on the DC side. A switch KM2 has one end connected to pin BUS+ of the AC / DC module and the other end connected to pin DC1 of the DC / DC module. A switch KM3 is connected at one end to pin DC2 of the DC / DC module and at the other end to the DC+ terminal on the DC side.

[0010] Furthermore, it also includes: An AC-side terminal N is connected to pin N of the AC / DC module; A switch KM4 is connected at one end to the BUS- pin of the AC / DC module and at the other end to the COM pin of the DC / DC module.

[0011] Furthermore, the highest operating voltage on the DC side of the AC / DC module is greater than the highest operating voltage of the DC / DC module.

[0012] Furthermore, the minimum operating voltage of the DC side of the AC / DC module is greater than the minimum operating voltage of the DC / DC module.

[0013] Secondly, the present invention provides a method for using a wide-voltage energy storage converter, comprising the following steps: Step S1: Connect the DC-side terminals DC+ and DC- to the energy storage device. If the energy storage device is a lithium battery, proceed to step S2; if the energy storage device is a flow battery or a supercapacitor, proceed to step S3. Step S2: Monitor the minimum DC voltage V1 of the energy storage device. When V1 is always ≥ the minimum operating voltage of the DC side of the AC / DC module, disconnect switches KM2, KM3 and KM4. The AC / DC module charges and discharges the energy storage device through switch KM1. When V1 < the minimum operating voltage of the DC side of the AC / DC module, and the maximum operating voltage of the DC side of the AC / DC module > the maximum DC voltage of the energy storage device > the maximum operating voltage of the DC / DC module, the segmented switching method is used to charge and discharge the energy storage device. Step S3: Monitor the DC voltage V2 of the energy storage device. When V2 is always less than the minimum operating voltage of the DC side of the AC / DC module, disconnect switch KM1 and close switches KM2, KM3 and KM4. Connect the AC / DC module and DC / DC module in series to charge and discharge the energy storage device. When a portion of V2 exceeds the minimum operating voltage on the DC side of the AC / DC module, a segmented switching method is used to charge and discharge the energy storage device.

[0014] Furthermore, the segmented switching method specifically refers to: a. Monitor the initial voltage V3 of the energy storage device. When V3 < the minimum operating voltage on the DC side of the AC / DC module: Disconnect switch KM1, close switches KM2 and KM4, and the AC / DC module will operate in constant voltage mode. The DC side voltage range is set to (the lowest operating voltage of the AC / DC module and the highest operating voltage of the DC / DC module). The DC / DC module first controls the voltage output of pin DC2 to be close to V3, and then closes switch KM3 to charge in constant current mode or constant power mode. As V3 increases, the duty cycle of the DC / DC module increases until it approaches 100%. When V3 ≥ the minimum operating voltage of the DC side of the AC / DC module, the duty cycle of the DC / DC module is fixed at 100% because the voltage output from pin DC2 of the DC / DC module is close to the voltage input from pin DC1. The AC / DC module switches to constant current module or constant power mode to continue charging. When the duty cycle of the DC / DC module reaches 100%, the voltage difference between pins DC1 and DC2 of the DC / DC module is lower than the preset threshold. Switch KM1 is closed, and switches KM2, KM3, and KM4 are opened, so that the DC / DC module stops working and is charged by the AC / DC module. b. When V3 ≥ the lowest operating voltage of the DC side of the AC / DC module and V3 ≥ the highest operating voltage of the DC / DC module, close switch KM1 and open switches KM2, KM3 and KM4, and the AC / DC module will charge the module.

[0015] The advantages of this invention are: 1. By enabling the AC / DC module and DC / DC module to work collaboratively under the control of the switching network, a low-cost advantage is achieved through the concept of "frequency division multiplexing": In the high-voltage range of the battery, only the high-efficiency AC / DC module works directly; in the low-voltage range of the battery, the AC / DC module is used as a stable DC source and connected in series with a DC / DC module that only needs to handle low voltage and small power capacity. The latter completes zero-voltage start-up and constant power output. This allows the system to cover the entire voltage range without the need for expensive high-voltage, high-power DC / DC converters. Thus, while possessing the capabilities of zero-voltage start-up, wide-voltage operation, and low-voltage constant power output, hardware costs and losses are significantly reduced.

[0016] 2. This invention supports 0V start-up of supercapacitors and flow batteries, as well as low-voltage constant power function, enabling PCS standardization within a voltage range (e.g., 0-1000V or 0-1500V), requiring only one product to meet various voltage requirements within that range; the power of the DC / DC module can be less than that of the AC / DC module, thereby reducing the overall cost; the DC / DC module is bypassed in the high-voltage section, and the AC / DC module directly performs charging and discharging, improving the maximum efficiency of the system; smooth switching between high and low voltages during charging and discharging avoids power transmission interruption and prevents load power loss under off-grid conditions.

[0017] 3. By combining AC / DC and DC / DC modules and integrating a switching mechanism, high-efficiency compatibility with energy storage devices (such as lithium batteries, flow batteries, or supercapacitors) with a wide voltage range is achieved. The DC-side operating voltage range of the AC / DC module is designed to be higher than that of the DC / DC module, which allows the converter to automatically adapt to different operating conditions from low voltage (such as the typical voltage of a flow battery) to high voltage (such as the full-charge voltage of a lithium battery). This improves the versatility of the system and the breadth of application scenarios, avoids the need to customize dedicated converters for different energy storage devices, and reduces the overall cost.

[0018] 4. Integrated segmented switching method: By monitoring the real-time voltage value of the energy storage device, the system dynamically controls the opening and closing of switches (such as KM1, KM2, KM3, and KM4) to enable the AC / DC module and DC / DC module to work in coordination or independently. This intelligent switching ensures that when the voltage fluctuates (such as when the voltage rises during charging), the system can smoothly transition to the optimal operating mode (for example, enabling the DC / DC module to boost the voltage at low voltage and directly using the AC / DC module at high voltage), reducing energy conversion losses, improving overall energy efficiency, and avoiding the efficiency decline caused by the module operating under non-ideal voltage conditions.

[0019] 5. The energy storage converter adopts a modular structure, in which the AC / DC module and the DC / DC module are flexibly connected through a switching network. This design not only simplifies the hardware layout but also enhances the reliability and maintainability of the system. For example, the introduction of switch KM4 allows the pin BUS- of the AC / DC module to be connected to the pin COM of the DC / DC module when needed, providing an additional ground or reference point path, thereby preventing overvoltage or undervoltage damage in case of voltage abnormalities and extending the module life. At the same time, the duty cycle control and threshold monitoring in the segmented switching method further ensure the smoothness of operation, reduce switching shocks, and improve the stability of the system in frequent charge and discharge cycles.

[0020] 6. Clear operating procedures are defined for different types of energy storage devices (such as lithium batteries, flow batteries, and supercapacitors). Users only need to select the appropriate mode according to the device type and voltage monitoring results to achieve automatic charging and discharging. This design reduces the complexity of operation, eliminates the need for manual intervention in switching, and ensures efficient operation even for devices with large voltage variations (such as supercapacitors) through details in the "segmented switching method" (such as duty cycle adjustment and voltage range setting). This expands the application potential of converters in hybrid energy storage systems and supports the diversified needs in the field of energy storage.

[0021] 7. By limiting the voltage relationship between the AC / DC module and the DC / DC module (such as the difference between the highest and lowest operating voltages) and combining it with the specific connection method of the switching network, a novel topology is formed, which solves the compatibility problem in wide voltage scenarios.

[0022] 8. Through the optimized combination of AC / DC and DC / DC modules, combined with intelligent switching networks (such as KM1, KM2, KM3, and KM4) and segmented switching methods, a wide voltage range of efficient adaptation to various energy storage devices (such as lithium batteries, flow batteries, and supercapacitors) is achieved, thereby improving the system's versatility and energy efficiency. Its modular design enhances reliability and maintainability, while intelligent voltage monitoring and automatic switching mechanisms ensure ease of operation and stability, ultimately providing an economical, flexible, and efficient solution for energy storage applications. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Figure 1 This is a circuit diagram of a wide-voltage energy storage converter according to the present invention.

[0025] Figure 2 This is a circuit diagram of the three-phase four-wire three-level AC / DC module combined with a half-bridge two-level DC / DC module of the present invention.

[0026] Figure 3 This is a circuit diagram of the three-phase three-wire three-level AC / DC module combined with a half-bridge two-level DC / DC module of the present invention.

[0027] Figure 4 This is a circuit diagram of the three-phase three-wire three-level AC / DC module with isolation transformer combined with a half-bridge two-level DC / DC module of the present invention.

[0028] Figure 5 This is a topology diagram of the DC / DC module of the present invention. Detailed Implementation

[0029] Please refer to Figures 1 to 5 As shown. Figure 2 In this system, the AC / DC converter adopts a three-phase four-wire NPC three-level architecture with split capacitors, while the DC / DC converter adopts a half-bridge architecture. The AC / DC converter can use IGBTs, MOS, or SiC MOS, and the DC / DC converter can use MOS, SiC MOS, or IGBTs, etc. Figure 3 In this system, the AC / DC converter adopts a three-phase three-wire NPC three-level architecture, while the DC / DC converter adopts a half-bridge architecture. This architecture is suitable for connecting to IT systems and is directly coupled to the high-voltage side through a transformer. Figure 4 In this system, the AC / DC converter adopts a three-phase three-wire NPC three-level architecture, while the DC / DC converter adopts a half-bridge architecture. This architecture is suitable for connecting to a TN-S system and is isolated to the low-voltage side through a transformer. Figure 5 In this DC / DC converter, a 2-level architecture is used, which can be multiple transistors in parallel or multiple groups in parallel to improve power and current. Preferably, each group uses 2-4 transistors in parallel, and preferably 3 groups to increase power. The groups can be interleaved in parallel to reduce ripple, or synchronous control can be used to simplify control complexity. The switching transistors used can be IGBTs, MOS, or SiC MOS.

[0030] A preferred embodiment of the wide-voltage energy storage converter of the present invention includes: An AC / DC module (bidirectional AC / DC), preferably with a three-level architecture; A DC / DC module (bidirectional DC / DC), preferably a two-level architecture; An AC-side terminal A is connected to pin A of the AC / DC module; An AC-side terminal B is connected to pin B of the AC / DC module; An AC side terminal C is connected to pin C of the AC / DC module; One DC-side terminal DC+; A DC- side terminal is connected to the BUS- pin of the AC / DC module; DC+ and DC- side terminals are used to connect energy storage devices such as lithium batteries, flow batteries, and supercapacitors. A switch KM1 has one end connected to the BUS+ (DC side positive terminal) pin of the AC / DC module, and the other end connected to the DC side terminal DC+. A switch KM2 has one end connected to the BUS+ pin of the AC / DC module and the other end connected to the DC1 pin (positive input terminal) of the DC / DC module. A switch KM3 is connected at one end to pin DC2 (positive output terminal) of the DC / DC module, and at the other end to the DC+ terminal on the DC side.

[0031] Also includes: An AC-side terminal N is connected to pin N of the AC / DC module; A switch KM4 is connected at one end to the BUS- (DC side negative) pin of the AC / DC module and at the other end to the COM pin of the DC / DC module.

[0032] In practical implementation, AC side terminal N and switch KM4 are optional components; without AC side terminal N, it is a three-phase three-wire system, and with AC side terminal N, it is a three-phase four-wire system.

[0033] The highest operating voltage on the DC side of the AC / DC module is greater than the highest operating voltage of the DC / DC module.

[0034] The minimum operating voltage on the DC side of the AC / DC module is greater than the minimum operating voltage of the DC / DC module. A preferred embodiment of the method for using a wide-voltage energy storage converter according to the present invention includes the following steps: Step S1: Connect the DC-side terminals DC+ and DC- to the energy storage device. If the energy storage device is a lithium battery, proceed to step S2; if the energy storage device is a flow battery or a supercapacitor, proceed to step S3. Step S2: Monitor the minimum DC voltage V1 of the energy storage device. When V1 is always ≥ the minimum operating voltage of the DC side of the AC / DC module, disconnect switches KM2, KM3 and KM4. The AC / DC module charges and discharges the energy storage device through switch KM1. When V1 < the minimum operating voltage of the DC side of the AC / DC module, and the maximum operating voltage of the DC side of the AC / DC module > the maximum DC voltage of the energy storage device > the maximum operating voltage of the DC / DC module, the segmented switching method is used to charge and discharge the energy storage device. Step S3: Monitor the DC voltage V2 of the energy storage device. When V2 is always less than the minimum operating voltage of the DC side of the AC / DC module, disconnect switch KM1 and close switches KM2, KM3 and KM4. Connect the AC / DC module and DC / DC module in series to charge and discharge the energy storage device. When a portion of V2 exceeds the minimum operating voltage on the DC side of the AC / DC module, a segmented switching method is used to charge and discharge the energy storage device.

[0035] The segmented switching method is specifically as follows: In charging mode: a. Monitor the initial voltage V3 of the energy storage device. When V3 < the minimum operating voltage on the DC side of the AC / DC module: Disconnect switch KM1, close switch KM2 and switch KM4. The AC / DC module operates in the constant voltage mode. The DC-side voltage range (equivalent to the DC1 voltage range after KM2 is closed) is set to (the lowest operating voltage of the DC side of the AC / DC module, the highest operating voltage of the DC / DC module). The DC / DC module first controls the voltage output by pin DC2 to be close to V3, and then closes switch KM3 (to achieve DC pre-charging), and charges in the constant current mode or constant power mode; As V3 continuously increases, the duty cycle of the DC / DC module continuously increases until it approaches 100%. When V3 ≥ the lowest operating voltage of the DC side of the AC / DC module, since the voltage output by pin DC2 of the DC / DC module is close to the voltage input by pin DC1, the duty cycle of the DC / DC module is fixed at 100%, and the AC / DC module switches to the constant current mode or constant power mode to continue charging; After the duty cycle of the DC / DC module reaches 100%, the voltage difference between pin DC1 and pin DC2 of the DC / DC module is lower than the preset threshold (such as <10V). Close switch KM1 (at this time, it is equivalent to the DC / DC module being in parallel with KM1 through the conduction of the power tube + KM2 + KM3, so the closing of KM1 is similar to zero-voltage switching on and has no impact on the charging process), disconnect switch KM2, switch KM3 and switch KM4 (the priority turn-off order is: KM3, KM2, KM4), so that the DC / DC module exits the operation, and the AC / DC module conducts charging; Since the AC / DC module has switched to the constant current mode or constant power mode to continue charging, stopping the DC / DC module and disconnecting switch KM2, switch KM3, and switch KM4 will not cause an impact or power outage to the system.

[0036] The voltage window allowed for the above switching operation is (the lowest operating voltage of the DC side of the AC / DC module, the highest operating voltage of the DC / DC module). Since the present invention sets the lowest operating voltage of the DC side of the AC / DC module < the highest operating voltage of the DC / DC module, there is enough time to achieve the switching.

[0037] b. When V3 ≥ the lowest operating voltage of the DC side of the AC / DC module and V3 ≥ the highest operating voltage of the DC / DC module, close switch KM1, disconnect switch KM2, switch KM3 and switch KM4, and the AC / DC module conducts charging.

[0038] This method can achieve an uninterrupted charging process.

[0039] In the discharge mode: When V3 is greater than or equal to the minimum operating voltage of the DC side of the AC / DC module and greater than or equal to the maximum operating voltage of the DC / DC module, the DC side voltage of the AC / DC module is first controlled to be close to V3 (e.g., <10V). Then, switch KM1 is closed (to achieve DC pre-charging), and switches KM2, KM3, and KM4 are opened. The energy storage device discharges through the AC / DC module. When V3 continuously drops to below the maximum operating voltage of the DC / DC module but above the minimum operating voltage of the DC side of the AC / DC module, switches KM2, KM3, and KM4 are closed, and the duty cycle inside the DC / DC module is set to 100%. Then, switch KM1 is opened, and pin DC1 of the DC / DC module operates in constant voltage mode, allowing the DC / DC module to discharge.

[0040] This method can ensure uninterrupted discharge, effectively preventing short-term power loss of devices powered by AC / DC modules in off-grid conditions, thus ensuring the stability of the system power supply and the power supply safety of high-priority loads.

[0041] This invention utilizes a switching mechanism to operate both the AC / DC module and the DC / DC module simultaneously at low voltage, while disconnecting the DC / DC module at high voltage, allowing the AC / DC module to directly connect to the energy storage device. A switching scheme is provided to achieve smooth high-to-low voltage switching, enabling a lower maximum operating voltage for the DC / DC module. Since the maximum operating voltage of the DC / DC module is lower than that of the AC / DC module, the maximum power required by the DC / DC module is lower under the same current conditions, resulting in lower cost. Through smooth high-to-low voltage switching, the DC / DC module is bypassed under high voltage conditions, thus achieving the efficiency of a single-stage AC / DC module and solving the efficiency problems of flow batteries and supercapacitors during charging and discharging.

[0042] In summary, the advantages of this invention are as follows: 1. By enabling the AC / DC module and DC / DC module to work collaboratively under the control of the switching network, a low-cost advantage is achieved through the concept of "frequency division multiplexing": In the high-voltage range of the battery, only the high-efficiency AC / DC module works directly; in the low-voltage range of the battery, the AC / DC module is used as a stable DC source and connected in series with a DC / DC module that only needs to handle low voltage and small power capacity. The latter completes zero-voltage start-up and constant power output. This allows the system to cover the entire voltage range without the need for expensive high-voltage, high-power DC / DC converters. Thus, while possessing the capabilities of zero-voltage start-up, wide-voltage operation, and low-voltage constant power output, hardware costs and losses are significantly reduced.

[0043] 2. This invention supports 0V start-up of supercapacitors and flow batteries, as well as low-voltage constant power function, enabling PCS standardization within a voltage range (e.g., 0-1000V or 0-1500V), requiring only one product to meet various voltage requirements within that range; the power of the DC / DC module can be less than that of the AC / DC module, thereby reducing the overall cost; the DC / DC module is bypassed in the high-voltage section, and the AC / DC module directly performs charging and discharging, improving the maximum efficiency of the system; smooth switching between high and low voltages during charging and discharging avoids power transmission interruption and prevents load power loss under off-grid conditions.

[0044] 3. By combining AC / DC and DC / DC modules and integrating a switching mechanism, high-efficiency compatibility with energy storage devices (such as lithium batteries, flow batteries, or supercapacitors) with a wide voltage range is achieved. The DC-side operating voltage range of the AC / DC module is designed to be higher than that of the DC / DC module, which allows the converter to automatically adapt to different operating conditions from low voltage (such as the typical voltage of a flow battery) to high voltage (such as the full-charge voltage of a lithium battery). This improves the versatility of the system and the breadth of application scenarios, avoids the need to customize dedicated converters for different energy storage devices, and reduces the overall cost.

[0045] 4. Integrated segmented switching method: By monitoring the real-time voltage value of the energy storage device, the system dynamically controls the opening and closing of switches (such as KM1, KM2, KM3, and KM4) to enable the AC / DC module and DC / DC module to work in coordination or independently. This intelligent switching ensures that when the voltage fluctuates (such as when the voltage rises during charging), the system can smoothly transition to the optimal operating mode (for example, enabling the DC / DC module to boost the voltage at low voltage and directly using the AC / DC module at high voltage), reducing energy conversion losses, improving overall energy efficiency, and avoiding the efficiency decline caused by the module operating under non-ideal voltage conditions.

[0046] 5. The energy storage converter adopts a modular structure, in which the AC / DC module and the DC / DC module are flexibly connected through a switching network. This design not only simplifies the hardware layout but also enhances the reliability and maintainability of the system. For example, the introduction of switch KM4 allows the pin BUS- of the AC / DC module to be connected to the pin COM of the DC / DC module when needed, providing an additional ground or reference point path, thereby preventing overvoltage or undervoltage damage in case of voltage abnormalities and extending the module life. At the same time, the duty cycle control and threshold monitoring in the segmented switching method further ensure the smoothness of operation, reduce switching shocks, and improve the stability of the system in frequent charge and discharge cycles.

[0047] 6. Clear operating procedures are defined for different types of energy storage devices (such as lithium batteries, flow batteries, and supercapacitors). Users only need to select the appropriate mode according to the device type and voltage monitoring results to achieve automatic charging and discharging. This design reduces the complexity of operation, eliminates the need for manual intervention in switching, and ensures efficient operation even for devices with large voltage variations (such as supercapacitors) through details in the "segmented switching method" (such as duty cycle adjustment and voltage range setting). This expands the application potential of converters in hybrid energy storage systems and supports the diversified needs in the field of energy storage.

[0048] 7. By limiting the voltage relationship between the AC / DC module and the DC / DC module (such as the difference between the highest and lowest operating voltages) and combining it with the specific connection method of the switching network, a novel topology is formed, which solves the compatibility problem in wide voltage scenarios.

[0049] 8. Through the optimized combination of AC / DC and DC / DC modules, combined with intelligent switching networks (such as KM1, KM2, KM3, and KM4) and segmented switching methods, a wide voltage range of efficient adaptation to various energy storage devices (such as lithium batteries, flow batteries, and supercapacitors) is achieved, thereby improving the system's versatility and energy efficiency. Its modular design enhances reliability and maintainability, while intelligent voltage monitoring and automatic switching mechanisms ensure ease of operation and stability, ultimately providing an economical, flexible, and efficient solution for energy storage applications.

[0050] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A wide voltage energy storage converter, characterized by: include: An AC / DC module; A DC / DC module; An AC-side terminal A is connected to pin A of the AC / DC module; An AC-side terminal B is connected to pin B of the AC / DC module; An AC side terminal C is connected to pin C of the AC / DC module; One DC-side terminal DC+; A DC- side terminal is connected to the BUS- pin of the AC / DC module; A switch KM1 has one end connected to the BUS+ pin of the AC / DC module and the other end connected to the DC+ terminal on the DC side. A switch KM2 has one end connected to pin BUS+ of the AC / DC module and the other end connected to pin DC1 of the DC / DC module. A switch KM3 is connected at one end to pin DC2 of the DC / DC module and at the other end to the DC+ terminal on the DC side.

2. A wide voltage energy storage converter as claimed in claim 1, characterized in that: Also includes: An AC-side terminal N is connected to pin N of the AC / DC module; A switch KM4 is connected at one end to the BUS- pin of the AC / DC module and at the other end to the COM pin of the DC / DC module.

3. A wide voltage energy storage converter as claimed in claim 1, characterized in that: The highest operating voltage on the DC side of the AC / DC module is greater than the highest operating voltage of the DC / DC module.

4. A wide voltage energy storage converter as recited in claim 1, wherein: The minimum operating voltage on the DC side of the AC / DC module is greater than the minimum operating voltage of the DC / DC module.

5. A method of using a wide voltage energy storage converter, characterized by: The method requires the use of a wide-voltage energy storage converter as described in any one of claims 1 to 4, and includes the following steps: Step S1: Connect the DC-side terminals DC+ and DC- to the energy storage device. If the energy storage device is a lithium battery, proceed to step S2; if the energy storage device is a flow battery or a supercapacitor, proceed to step S3. Step S2: Monitor the minimum DC voltage V1 of the energy storage device. When V1 is always ≥ the minimum operating voltage of the DC side of the AC / DC module, disconnect switches KM2, KM3 and KM4. The AC / DC module charges and discharges the energy storage device through switch KM1. When V1 < the lowest operating voltage of the DC side of the AC / DC module, and the highest operating voltage of the DC side of the AC / DC module > the highest DC voltage of the energy storage device > the highest operating voltage of the DC / DC module, the segmented switching method is used to charge and discharge the energy storage device. Step S3: Monitor the DC voltage V2 of the energy storage device. When V2 is always less than the minimum operating voltage of the DC side of the AC / DC module, disconnect switch KM1 and close switches KM2, KM3 and KM4. Connect the AC / DC module and DC / DC module in series to charge and discharge the energy storage device. When a portion of V2 exceeds the minimum operating voltage on the DC side of the AC / DC module, a segmented switching method is used to charge and discharge the energy storage device.

6. A method of using a wide voltage energy storage converter as claimed in claim 5, characterized by: The segmented switching method is specifically as follows: a. Monitor the initial voltage V3 of the energy storage device. When V3 < the minimum operating voltage on the DC side of the AC / DC module: Disconnect switch KM1, close switches KM2 and KM4, and the AC / DC module will operate in constant voltage mode. The DC side voltage range is set to (the lowest operating voltage of the AC / DC module and the highest operating voltage of the DC / DC module). The DC / DC module first controls the voltage output of pin DC2 to be close to V3, and then closes switch KM3 to charge in constant current mode or constant power mode. As V3 increases, the duty cycle of the DC / DC module increases until it approaches 100%. When V3 ≥ the minimum operating voltage of the DC side of the AC / DC module, the duty cycle of the DC / DC module is fixed at 100% because the voltage output from pin DC2 of the DC / DC module is close to the voltage input from pin DC1. The AC / DC module switches to constant current module or constant power mode to continue charging. When the duty cycle of the DC / DC module reaches 100%, the voltage difference between pins DC1 and DC2 of the DC / DC module is lower than the preset threshold. Switch KM1 is closed, and switches KM2, KM3, and KM4 are opened, causing the DC / DC module to stop working and be charged by the AC / DC module. b. When V3 ≥ the lowest operating voltage of the DC side of the AC / DC module and V3 ≥ the highest operating voltage of the DC / DC module, close switch KM1 and open switches KM2, KM3 and KM4, and the AC / DC module will charge the module.

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