High-voltage direct-hanging energy storage system based on DC-DC and control method thereof

Abstract

The invention provides a DC-DC-based high-voltage direct-hanging energy storage system and a control method thereof, and belongs to the technical field of high-voltage direct-hanging energy storage systems.The system comprises a plurality of battery packs and a plurality of power modules, the battery packs and the power modules are connected into a middle-high voltage power grid in a cascade connection mode, and the power modules are connected into the middle-high voltage power grid in a cascade connection mode. An isolation topology module is connected in parallel between the battery pack and the power module; the isolation topology module comprises a common mode inductor # imgabs0 # and a current stabilization unit; the first end of the common mode inductor # imgabs 1 # is connected with the battery pack, the second end of the common mode inductor # imgabs 2 # is connected with the first end of the current stabilization unit, and the second end of the current stabilization unit is connected with the power module. Through the isolation topology module, common-mode interference is effectively suppressed, secondary pulsating current can be effectively absorbed, and through an LC passive filter composed of a common-mode inductor # imgabs3 # and a direct-current voltage-stabilizing capacitor C1, the problems of common-mode interference and secondary pulsating current brought by parasitic parameters of the cable are more effectively suppressed.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-voltage direct-mounted energy storage systems, and in particular relates to a DC-DC-based high-voltage direct-mounted energy storage system and a control method thereof. Background Art

[0002] As the proportion of renewable energy connected to the power grid increases, the power fluctuation problem caused by photovoltaic and wind power is becoming increasingly prominent. The deployment of a series of energy storage systems can effectively solve the power fluctuation problem.

[0003] Lithium-ion battery technology, primarily lithium iron phosphate batteries, is relatively mature, offering advantages such as high safety and low cost. Energy storage power stations already utilize battery packs primarily based on lithium-ion batteries. However, most energy storage power stations still utilize centralized or string-type parallel connections, connecting to medium- and high-voltage power grids via step-up transformers. This type of grid-connected energy storage suffers from significant power losses and high costs.

[0004] In order to reduce the conversion link between DC batteries and AC power grid, improve the overall efficiency of energy storage power stations and simplify the conversion link, high-voltage direct-mounted energy storage systems are usually used.

[0005] However, in existing high-voltage direct-mounted energy storage systems, there is a common-mode interference problem between the battery pack and the power module. The secondary pulsating current on the battery pack side affects the normal operation of the high-voltage direct-mounted energy storage. Therefore, how to solve the common-mode interference, secondary pulsating current and high-voltage ride-through of the battery pack has become a technical problem that needs to be solved. Summary of the Invention

[0006] The present invention provides a DC-DC-based high-voltage direct-mounted energy storage system and a control method thereof, so as to at least solve the problem of common-mode interference between a battery pack and a power module in the prior art.

[0007] In a first aspect, an embodiment of the present application provides a DC-DC-based high-voltage direct-mounted energy storage system, the system comprising a plurality of battery packs and a plurality of power modules, the battery packs and the power modules being connected to a medium- and high-voltage power grid in a cascaded manner, with an isolation topology module being connected in parallel between the battery packs and the power modules; The isolation topology module includes a common mode inductor and flow stabilization unit; The common mode inductor The first end is connected to the battery pack through a cable, the common mode inductor The second end of the current stabilizing unit is connected to the first end of the current stabilizing unit, and the second end of the current stabilizing unit is connected to the power module.

[0008] Furthermore, the current stabilization unit includes a DC side voltage stabilization capacitor C1, an inductor L3, a cascaded DC-DC converter G11, a cascaded DC-DC converter G12, a cascaded DC-DC converter G13, a cascaded DC-DC converter G14 and a pulsation buffer capacitor C2; The first end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G11 and the collector of the cascaded DC-DC converter G13; The collector of the cascaded DC-DC converter G11 is connected to the first end of the DC side voltage stabilizing capacitor C1 and then connected to the common mode inductor The second end of The emitter of the cascaded DC-DC converter G13 is connected to the second end of the DC side voltage stabilizing capacitor C1 and then connected to the common mode inductor. the second end; The second end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G12 and the collector of the cascaded DC-DC converter G14; The collector of the cascaded DC-DC converter G12 is connected to the first end of the pulsation buffer capacitor C2 and then connected to the upper output end of the power module; The emitter of the cascaded DC-DC converter G14 is connected to the second end of the pulsating buffer capacitor C2 and then connected to the lower output end of the power module; Common mode choke Together with the DC side voltage stabilizing capacitor C1, it forms an LC passive filter.

[0009] Furthermore, the common-mode current interference is regarded as a step response of a voltage pulse, where the common-mode interference current corresponding to a power module is:

[0010] in:

[0011] Where, is the common mode interference current, is the voltage of a battery pack, is the number of battery packs corresponding to one power module, is the parasitic capacitance of the cable, is the parasitic inductance of the cable, is the line parasitic resistance, is the parasitic resistance to ground, is the number of power modules connected in parallel in a phase of three-phase AC power, and For The correlation coefficient, is a power module connected in parallel; Parasitic capacitance of the cable Compared to the parasitic inductance of the cable , Line parasitic resistance , parasitic resistance to ground Small, so it can be ignored. At this time, the common mode interference current The peak value is:

[0012] Where, Common mode interference current Peak value; Adding common-mode inductors Common mode interference current after The peak value is:

[0013] Where, To add common mode inductance Common mode interference current after peak value.

[0014] Furthermore, the common mode inductor Together with the DC side voltage stabilizing capacitor C1, it forms an LC passive filter to suppress the secondary pulsating current; By not including common mode inductance The energy storage system is subjected to Fourier transform and carrier phase shift modulation strategy to calculate the secondary pulsating current:

[0015] Where, is the secondary pulsating current, is the DC side current component, is the internal resistance of the battery; Through common mode inductors Together with the DC side voltage stabilizing capacitor C1, an LC passive filter is formed to suppress the secondary pulsating current. The secondary pulsating current after passing through the LC passive filter is:

[0016] At this time, it becomes a second-order oscillation system, which suppresses the secondary pulsating current to a certain extent in a short time.

[0017] Furthermore, the working modes of the current stabilization unit are: boost mode and buck mode; Battery power generation: In boost mode, only cascaded DC-DC converter G12 and cascaded DC-DC converter G14 are working; in buck mode, only cascaded DC-DC converter G11 and cascaded DC-DC converter G13 are working; Battery charging: In boost mode, only cascaded DC-DC converter G11 and cascaded DC-DC converter G13 work; in buck mode, only cascaded DC-DC converter G12 and cascaded DC-DC converter G14 work.

[0018] Furthermore, in the boost mode, the cascaded DC-DC converter G11 is turned on. At this time, the cascaded DC-DC converter G12 and the cascaded DC-DC converter G14 are controlled by the modulation signal to increase the voltage output to the power module. The expression of the voltage output to the power module is:

[0019] Where, , , is the input side voltage, is the voltage output to the power module, is the inductor current. According to the volt-second balance theory, we get: .

[0020] Furthermore, the system further comprises: an AC isolating switch S1, a soft start switch S2, a reactor L1, and a soft start resistor R1; The soft start switch S2 is connected in series with the soft start resistor R1; The first end of the soft start switch S2 and the first end of the AC isolation switch S1 are connected to the medium and high voltage power grid; The second end of the soft start switch S2 is connected to the first end of the soft start resistor R1; The second end of the soft-start resistor R1 and the second end of the AC isolating switch S1 are connected to the first end of the reactor L1; The second end of the reactor L1 is connected to the upper output end of the power module.

[0021] In a second aspect, embodiments of the present application further provide a control method for a DC-DC-based high-voltage direct-mounted energy storage system as described in the above aspects, the method comprising: Step S1: Estimate the SOC status of the battery pack. When the SOC status of the battery pack is less than or equal to 20% power, execute step S2; otherwise, execute step S3; Step S2: No discharge is performed, an early warning is issued, and other battery packs are coordinated to discharge, and the process returns to step S1; Step S3: setting the output voltage of the DC-DC converter and selecting the operating mode according to the fluctuation of the grid voltage; Step S4: increasing or decreasing the voltage output to the power module based on the selected operating mode; Step S5: Calculate and increase or decrease the voltage output to the power module; Step S6: Determine whether the voltage difference between the voltage output to the power module and the grid voltage is less than 5% of the grid voltage. If so, end the process; otherwise, return to step S3.

[0022] In a third aspect, an electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the control method as described in the above aspects when executing the program.

[0023] In a fourth aspect, a storage medium stores a computer program thereon, wherein the computer program, when executed by a processor, implements the steps of the control method as described in the above aspects.

[0024] It can be seen from the above technical solutions that the present invention has the following advantages: The present application provides a DC-DC based high voltage direct hanging energy storage system and its control method, through the isolation topology module, effectively suppresses the common mode interference and enables the secondary pulsating current to be effectively absorbed, through the common mode inductor , effectively suppressing the common-mode interference problem caused by cable parasitic parameters.

[0025] Common mode choke Together with the DC side voltage stabilizing capacitor C1, it forms an LC passive filter. Through the isolation topology module composed of the LC passive filter and the DC-DC converter, the secondary pulsating current is suppressed, solving the secondary pulsating current problem on the battery pack side.

[0026] The DC-DC converter also achieves higher voltage gain through a cascade topology, increases the buffer capacitor voltage amplitude to suppress secondary pulsating current, and enables the battery pack to increase or decrease the voltage output to the power module according to actual operating conditions, completing high-voltage ride-through conditions when the grid voltage fluctuates, improving the high-voltage ride-through capability of the energy storage system, and ensuring the stable operation of high-voltage direct-mounted energy storage.

[0027] By directly connecting multiple battery packs and power modules in cascade to the medium and high voltage power grid, the step-up transformer is eliminated; this grid-connected method reduces power loss and costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for the description. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] Figure 1This is a topological diagram of the DC-DC-based high-voltage direct-mounted energy storage system of the present invention.

[0030] Figure 2 This is a topological diagram of the isolation module of the DC-DC-based high-voltage direct-mounted energy storage system of the present invention.

[0031] Figure 3 This is a state diagram of the boost working mode of the cascaded DC-DC converter of the DC-DC-based high-voltage direct-mounted energy storage system of the present invention.

[0032] Figure 4 This is a state diagram of the step-down working mode of the cascaded DC-DC converter of the DC-DC-based high-voltage direct-mounted energy storage system of the present invention.

[0033] Figure 5 This is a simulation diagram of the secondary pulsating current of the DC-DC-based high-voltage direct-mounted energy storage system of the present invention.

[0034] Figure 6 This is a modulation diagram of the cascaded DC-DC converter of the DC-DC-based high-voltage direct-mounted energy storage system of the present invention.

[0035] Figure 7 This is a flow chart of a control method for a DC-DC-based high-voltage direct-mounted energy storage system according to the present invention.

[0036] Figure 8 This is a simulation diagram of the DC-DC converter output voltage of the DC-DC-based high-voltage direct-mounted energy storage system of the present invention. DETAILED DESCRIPTION

[0037] In order to make the application objectives, features, and advantages of this application more obvious and easy to understand, the technical solutions protected by this application will be clearly and completely described below using specific embodiments and drawings. Obviously, the embodiments described below are only part of the embodiments of this application, not all of them. Based on the embodiments in this patent, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this patent.

[0038] The present invention provides a DC-DC-based high-voltage direct-mounted energy storage system and energy storage unit control strategy, which solves the common-mode interference problem of existing energy storage systems. The two-stage pulsating current suppression circuit composed of LC filtering and DC-DC converter solves the secondary pulsating current problem on the battery pack side, and realizes the increase or decrease of the voltage output to the power module of the energy storage battery pack according to the actual working conditions, and improves the high-voltage ride-through capability of the energy storage system, ensuring the stable operation of high-voltage direct-mounted energy storage.

[0039] The technical solutions proposed in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0040] Combine Figure 1 and Figure 2 , an embodiment of the present application provides a DC-DC-based high-voltage direct-mounted energy storage system, the system including a plurality of battery packs and a plurality of power modules, the battery packs and the power modules being connected to a medium- and high-voltage power grid in a cascaded manner. The energy storage system is developing towards high voltage, large capacity, and clustered types. The present invention directly connects multiple battery packs and power modules in a cascaded manner to a medium- and high-voltage power grid, eliminating the need for a step-up transformer; this grid-connected method reduces power loss and cost.

[0041] An isolation topology module is connected in parallel between the battery pack and the power module; The isolation topology module includes a common mode inductor and flow stabilization unit; The common mode inductor The first end is connected to the battery pack, the common mode inductor The second end of the current stabilizing unit is connected to the first end of the current stabilizing unit, and the second end of the current stabilizing unit is connected to the power module.

[0042] The battery pack of the high-voltage direct-mounted energy storage system is usually placed in a remote area far away from the power module for safety performance and high voltage level considerations. Its cable is long and has a thick cross-sectional area. At this time, the common-mode interference caused by the parasitic parameters of the cable cannot be ignored. There is also a secondary pulsating current between the battery pack and the power module. Long-term operation will damage the battery pack and cause safety accidents. The present invention effectively suppresses common-mode interference and effectively absorbs the secondary pulsating current through the isolation topology module. , effectively suppressing the common-mode interference problem caused by cable parasitic parameters.

[0043] In an exemplary embodiment, the current stabilization unit includes a DC-side stabilizing capacitor C1, an inductor L3, a cascaded DC-DC converter G11, a cascaded DC-DC converter G12, a cascaded DC-DC converter G13, a cascaded DC-DC converter G14, and a pulsation buffer capacitor C2; The first end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G11 and the collector of the cascaded DC-DC converter G13; The collector of the cascaded DC-DC converter G11 is connected to the first end of the DC side voltage stabilizing capacitor C1 and then connected to the common mode inductor the second end; The emitter of the cascaded DC-DC converter G13 is connected to the second end of the DC side voltage stabilizing capacitor C1 and then connected to the common mode inductor. the second end; The second end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G12 and the collector of the cascaded DC-DC converter G14; The collector of the cascaded DC-DC converter G12 is connected to the first end of the pulsation buffer capacitor C2 and then connected to the upper output end of the power module; The emitter of the cascaded DC-DC converter G14 is connected to the second end of the pulsating buffer capacitor C2 and then connected to the lower output end of the power module; Common mode choke Together with the DC side voltage stabilizing capacitor C1, it forms an LC passive filter.

[0044] like Figure 2 , the secondary pulsating current is effectively suppressed by cascading DC-DC converters. The cascaded DC-DC converters are set up, and the pulsating buffer capacitor C2 is not directly connected in parallel with the battery pack. At this time, the cascaded DC-DC converters are used to increase the voltage amplitude of the pulsating buffer capacitor and suppress the secondary pulsating current. In addition, the cascaded DC-DC converter has a higher voltage gain than other converters, which meets the design requirements of the high-voltage direct-mounted energy storage system.

[0045] Common mode choke Together with the DC side voltage stabilizing capacitor C1, it forms an LC passive filter. Through the isolation topology module composed of the LC passive filter and the DC-DC converter, the secondary pulsating current is suppressed, solving the secondary pulsating current problem on the battery pack side.

[0046] The DC-DC converter also achieves higher voltage gain through a cascade topology, increases the buffer capacitor voltage amplitude to suppress secondary pulsating current, and enables the battery pack to increase or decrease the voltage output to the power module according to actual operating conditions. Through effective logic control, it completes the high-voltage ride-through operating conditions when the grid voltage fluctuates, improves the high-voltage ride-through capability of the energy storage system, and ensures the stable operation of high-voltage direct-mounted energy storage.

[0047] As an example, consider the common-mode current interference as a step response of a voltage pulse, where the common-mode interference current corresponding to a power module is:

[0048] in:

[0049] Where, is the common mode interference current, is the voltage of a battery pack, is the number of battery packs corresponding to one power module, is the parasitic capacitance of the cable, is the parasitic inductance of the cable, is the line parasitic resistance, is the parasitic resistance to ground, is the number of power modules connected in parallel in a phase of three-phase AC power, and For The correlation coefficient, is a power module connected in parallel; Parasitic capacitance of the cable Compared to the parasitic inductance of the cable , Line parasitic resistance , parasitic resistance to ground Small, so it can be ignored. At this time, the common mode interference current The peak value is:

[0050] Where, Common mode interference current Peak value; At this time, the peak value of the common-mode interference current generated by multiple parallel-connected power modules in one phase increases the current stress of the power module due to its long-term existence, thereby increasing loss and heat generation. like Figure 2 , the circuit diagram of the isolation topology module is given.

[0051] It is understandable that Figure 2 in is the common-mode inductor, C1 is the DC-side voltage-stabilizing capacitor, G11, G12, G13 and G14 are cascaded DC-DC converter IGBTs, and C2 is the pulsation buffer capacitor.

[0052] Furthermore, common mode inductance It has a suppressive effect on common mode interference current. Through the above derivation of the peak value of common mode interference current, it can be known that adding common mode inductance Common mode interference current after The peak value is:

[0053] Where, To add common mode inductance Common mode interference current after Peak value; Among them, the common mode inductor Much larger than the parasitic inductance of the cable , parasitic capacitance of the cable ,at this time Much smaller than .

[0054] It should be noted that the parasitic inductance of the cable The common mode inductor is 60μH Between 2mH-10mH, therefore, add the common mode inductance The denominator increases significantly, add common mode inductor Common mode interference current after Peak The peak value is significantly reduced, i.e. Much smaller than .

[0055] In one embodiment, the common mode inductor Together with the DC side voltage stabilizing capacitor C1, it forms an LC passive filter to suppress the secondary pulsating current; By not including common mode inductance The energy storage system is subjected to Fourier transform and carrier phase shift modulation strategy to calculate the secondary pulsating current:

[0056] Where, is the secondary pulsating current, is the DC side current component, is the internal resistance of the battery; Through common mode inductors The LC passive filter formed by the DC side voltage stabilizing capacitor C1 can suppress the secondary pulsating current. The secondary pulsating current after passing through the LC passive filter is:

[0057] At this time, it becomes a second-order oscillation system, which suppresses the secondary pulsating current to a certain extent in a short time.

[0058] According to the embodiments of the present application, Figure 3 and Figure 4 ,The working modes of the current stabilization unit are: boost mode and buck mode; Battery power generation: In boost mode, only cascaded DC-DC converter G12 and cascaded DC-DC converter G14 are working; in buck mode, only cascaded DC-DC converter G11 and cascaded DC-DC converter G13 are working; Battery charging: In boost mode, only cascaded DC-DC converter G11 and cascaded DC-DC converter G13 work; in buck mode, only cascaded DC-DC converter G12 and cascaded DC-DC converter G14 work.

[0059] Figure 6 Modulation diagram of the cascaded DC-DC converter. Figure 6 middle, It is the carrier signal of battery power generation boost mode. It is the carrier signal of the battery power generation buck mode. It is the modulation wave control signal.

[0060] It can be understood that the SOC state of the battery pack is first determined, and the PWM modulation is adjusted according to the SOC state of the battery pack to increase the voltage and shorten the charge and discharge time of the battery pack; taking the battery pack power generation mode as an example, when working in the boost mode, the modulation wave control signal Greater than the carrier signal of the battery power generation buck mode At this time, the cascaded DC-DC converter G11 is turned on, and the cascaded DC-DC converter G12 and the cascaded DC-DC converter G14 are alternately turned on to achieve voltage boosting.

[0061] According to another embodiment of the present invention, in the boost mode, the cascaded DC-DC converter G11 is turned on. At this time, the cascaded DC-DC converter G12 and the cascaded DC-DC converter G14 are controlled by a modulation signal to increase the voltage output to the power module. The expression of the voltage output to the power module is:

[0062] Where, , , is the input side voltage, is the voltage output to the power module, is the inductor current. According to the volt-second balance theory, we get: .

[0063] It should be noted that the system further includes: an AC isolating switch S1, a soft start switch S2, a reactor L1, and a soft start resistor R1; The soft start switch S2 is connected in series with the soft start resistor R1; The first end of the soft start switch S2 and the first end of the AC isolation switch S1 are connected to the medium and high voltage power grid; The second end of the soft start switch S2 is connected to the first end of the soft start resistor R1; The second end of the soft-start resistor R1 and the second end of the AC isolating switch S1 are connected to the first end of the reactor L1; The second end of the reactor L1 is connected to the upper output end of the power module.

[0064] Combine Figure 1 AC disconnect switch S1 disconnects the energy storage system and connects it to the medium- and high-voltage grid. Soft-start switch S2 and soft-start resistor R1 reduce the inrush current during grid connection. Reactor L1 filters the energy storage system's output current and suppresses sudden current fluctuations.

[0065] Combine Figure 6The present invention further provides a control method for a DC-DC-based high-voltage direct-mounted energy storage system as described in the above embodiments, the method comprising: Step S1: Estimate the SOC status of the battery pack. When the SOC status of the battery pack is less than or equal to 20% power, execute step S2; otherwise, execute step S3; Step S2: No discharge is performed, an early warning is issued, and other battery packs are coordinated to discharge, and the process returns to step S1; Step S3: setting the output voltage of the DC-DC converter and selecting the operating mode according to the fluctuation of the grid voltage; Step S4: increasing or decreasing the voltage output to the power module based on the selected operating mode; Step S5: Calculate and increase or decrease the voltage output to the power module; Step S6: Determine whether the voltage difference between the voltage output to the power module and the grid voltage is less than 5% of the grid voltage. If so, end the process; otherwise, return to step S3.

[0066] Figure 8 This is the DC-DC converter output voltage simulation diagram, such as Figure 8 When the battery starts to discharge, the voltage rises sharply due to the influence of the dual closed-loop control PI regulator, but the existence of the soft-start resistor does not damage the circuit. As the voltage gradually stabilizes, the grid voltage begins to rise slightly at 0.8s, and the DC-DC converter gradually increases to 5% of the grid voltage, which is 1 / N1 times the grid voltage amplitude.

[0067] DC-DC converters not only suppress secondary pulsating currents, but also prevent high-voltage ride-through (HVRT) in high-voltage, direct-mounted energy storage systems when grid voltage fluctuates. This invention achieves HVRT by cascading DC-DC converters in buck-boost mode, increasing or decreasing the DC-side voltage of the power module.

[0068] It should be noted that, according to the power given value and the three-phase voltage and current, the voltage acquisition amount after dq transformation is used to obtain the reference current value, and the reference current value and the current acquisition amount after dq transformation are subjected to PI control and park inverse transformation to obtain the reference three-phase voltage value; The reference three-phase voltage value and the zero-sequence voltage output by the converter of the power module are injected into the PWM modulation to perform inter-phase power compensation and realize the current conversion control of high-voltage direct-mounted energy storage.

[0069] The control method of the DC-DC-based high-voltage direct-mounted energy storage system provided in the embodiment of the present application can be applied to electronic devices. Those skilled in the art will understand that the electronic device structure involved in the embodiment of the present invention does not constitute a limitation on the electronic device, and the electronic device may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently. In the embodiment of the present invention, the electronic device includes but is not limited to laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the embodiments of the present application described and / or required herein.

[0070] The electronic device may include a processor, an external memory interface, an internal memory, a universal serial bus (USB) interface, a charging management module, a power management module, a battery, a wireless communication module, an audio module, a speaker, a microphone, a sensor module, a button, a camera, a display, and a SIM card interface, etc.

[0071] It is understood that the structures illustrated in the embodiments of the present application do not constitute specific limitations on the electronic device. In other embodiments of the present application, the electronic device may include more or fewer components than shown, or combine or separate certain components, or arrange the components differently. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0072] A processor may include one or more processing units, such as a central processing unit (CPU), an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a memory, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural-network processing unit (NPU). Different processing units may be independent devices or integrated into one or more processors.

[0073] The processor can be the nerve center and command center of the electronic device. The controller can generate operation control signals based on the instruction opcode and timing signal to complete the control of instruction fetching and execution.

[0074] The processor may also include a memory for storing instructions and data. In some embodiments, the memory in the processor is a cache memory. This memory can store instructions or data that the processor has just used or is reusing. If the processor needs to use the instruction or data again, it can directly call it from the memory. This avoids repeated accesses, reduces processor latency, and thus improves system efficiency.

[0075] The external memory interface can be used to connect an external memory card, such as a MicroSD card, to expand the storage capacity of an electronic device. The external memory card communicates with the processor through the external memory interface, enabling data storage. For example, files such as music and videos can be stored on the external memory card.

[0076] Internal memory can be used to store computer-executable program code, which includes instructions. The processor executes the instructions stored in the internal memory to perform various functional applications and data processing of the electronic device. The internal memory can include a program storage area and a data storage area. The internal memory can include high-speed random access memory and non-volatile memory, such as at least one disk storage device, flash memory device, universal flash storage (UFS), etc.

[0077] The wireless communication function of electronic devices can be realized through antennas, wireless communication modules, modem processors, and baseband processors.

[0078] Wireless communication modules can provide wireless communication solutions for electronic devices, including wireless local area networks (WLAN) (such as wireless fidelity (Wi-Fi) networks), Bluetooth (BT), global navigation satellite system (GNSS), frequency modulation (FM), near field communication (NFC), infrared technology (IR), etc.

[0079] Electronic devices can implement audio functions through audio modules, speakers, receivers, microphones, headphone jacks, and application processors.

[0080] Electronic devices can achieve shooting functions through ISP, camera, video codec, GPU, display and application processor.

[0081] Electronic devices can achieve display functions through GPU, display screen and application processor.

[0082] A GPU is a microprocessor for image processing that connects the display screen to the application processor. The GPU performs mathematical and geometric calculations for graphics rendering. A processor may include one or more GPUs, which execute program instructions to generate or modify display information.

[0083] The display screen is used to display images, videos, etc. The display screen includes a display panel.

[0084] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the composition and steps of each example according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0085] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the devices, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or a part of code, and the module, program segment, or a part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. Exemplarily, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0086] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or can be electrical, mechanical or other forms of connection.

[0087] In addition, the described features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present invention. However, it will be appreciated by those skilled in the art that the technical solutions of the present invention can be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring various aspects of the present invention.

[0088] The above-mentioned electronic device implements the control method of the DC-DC-based high-voltage direct-mounted energy storage system of the present application, and the method includes: step S1: estimating the SOC status of the battery pack. When the SOC status of the battery pack is less than or equal to 20% of the power, executing step S2, otherwise, executing step S3; step S2: not discharging, issuing an early warning and coordinating other battery packs to discharge, and returning to execute step S1; step S3: setting the output voltage of the DC-DC converter and selecting the working mode according to the fluctuation of the grid voltage; step S4: based on the selected working mode, increasing or decreasing the voltage output to the power module; step S5: calculating the increase or decrease of the voltage output to the power module; step S6: judging whether the voltage difference between the voltage output to the power module and the grid voltage is less than 5% of the grid voltage, if it is less, ending, otherwise, returning to execute step S3, through the isolation topology module, effectively suppressing common-mode interference and enabling the secondary pulsating current to be effectively absorbed, through the common-mode inductor , effectively suppressing the common-mode interference problem caused by cable parasitic parameters.

[0089] The storage medium provided in the present application stores a program product that can implement a control method for a DC-DC-based high-voltage direct-mounted energy storage system.

[0090] The control method of the DC-DC-based high-voltage direct-mounted energy storage system includes: estimating the SOC status of the battery pack, when the SOC status of the battery pack is less than or equal to 20% of the power, not discharging, issuing a warning and coordinating other battery packs to discharge, otherwise, according to the fluctuation of the grid voltage, setting the output voltage of the DC-DC converter and selecting the working mode; based on the selected working mode, increasing or decreasing the voltage output to the power module; calculating the increase or decrease in the voltage output to the power module; judging whether the voltage difference between the voltage output to the power module and the grid voltage is less than 5% of the grid voltage, and ending if it is less.

[0091] DC-DC converters not only suppress secondary pulsating currents, but also prevent high-voltage ride-through (HVRT) in high-voltage, direct-mounted energy storage systems when grid voltage fluctuates. This invention achieves HVRT by cascading DC-DC converters in buck-boost mode, increasing or decreasing the DC-side voltage of the power module.

[0092] In some possible embodiments, the control method of the DC-DC-based high-voltage direct-mounted energy storage system disclosed in the present invention can be implemented in the form of a program product, which includes a program code. When the program product is run on a terminal device, the program code is used to enable the terminal device to execute the steps of various exemplary embodiments of the present disclosure described in the above "Exemplary Method" section of this specification.

[0093] The storage medium of the present disclosure can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but not limited to, a system, device or component of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination thereof. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof.

[0094] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

[0095] For those skilled in the art, designing different forms of control circuits based on the teachings of the present invention does not require creative work. These changes, modifications, substitutions and variations to the embodiments without departing from the principles and spirit of the present invention still fall within the scope of protection of the present invention.

Claims

1. A DC-DC-based high-voltage direct-mounted energy storage system, comprising a plurality of battery packs and a plurality of power modules, wherein the battery packs and the power modules are connected to a medium- and high-voltage power grid in a cascaded manner, characterized in that: An isolation topology module is connected in parallel between the battery pack and the power module; The isolation topology module includes a common mode inductor and flow stabilization unit; The common mode inductor The first end is connected to the battery pack through a cable, the common mode inductor The second end of the current stabilizing unit is connected to the first end of the current stabilizing unit, and the second end of the current stabilizing unit is connected to the power module.

2. The DC-DC-based high-voltage direct-mounted energy storage system according to claim 1, characterized in that: The current stabilization unit includes a DC side voltage stabilization capacitor C1, an inductor L3, a cascaded DC-DC converter G11, a cascaded DC-DC converter G12, a cascaded DC-DC converter G13, a cascaded DC-DC converter G14 and a pulsation buffer capacitor C2; The first end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G11 and the collector of the cascaded DC-DC converter G13; The collector of the cascaded DC-DC converter G11 is connected to the first end of the DC side voltage stabilizing capacitor C1 and then connected to the common mode inductor The second end of The emitter of the cascaded DC-DC converter G13 is connected to the second end of the DC side voltage stabilizing capacitor C1 and then connected to the common mode inductor. The second end of The second end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G12 and the collector of the cascaded DC-DC converter G14; The collector of the cascaded DC-DC converter G12 is connected to the first end of the pulsation buffer capacitor C2 and then connected to the upper output end of the power module; The emitter of the cascaded DC-DC converter G14 is connected to the second end of the pulsating buffer capacitor C2 and then connected to the lower output end of the power module; Common mode choke Together with the DC side voltage stabilizing capacitor C1, it forms an LC passive filter.

3. The DC-DC-based high-voltage direct-mounted energy storage system according to claim 2, characterized in that: The common-mode current interference is regarded as the step response of the voltage pulse, where the common-mode interference current corresponding to one power module is: in: Where, is the common mode interference current, is the voltage of a battery pack, is the number of battery packs corresponding to one power module, is the parasitic capacitance of the cable, is the parasitic inductance of the cable, is the line parasitic resistance, is the parasitic resistance to ground, is the number of power modules connected in parallel in a phase of three-phase AC power, and For The associated coefficient, is a power module connected in parallel; Parasitic capacitance of the cable Compared to the parasitic inductance of the cable , Line parasitic resistance , parasitic resistance to ground Small, so it can be ignored. At this time, the common mode interference current The peak value is: Where, Common mode interference current Peak value; Adding common-mode inductors Common mode interference current after The peak value is: Where, To add common mode inductance Common mode interference current after peak value.

4. The DC-DC-based high-voltage direct-mounted energy storage system according to claim 1, characterized in that: Common mode choke Together with the DC side voltage stabilizing capacitor C1, it forms an LC passive filter to suppress the secondary pulsating current; By not including common mode inductance The energy storage system is subjected to Fourier transform and carrier phase shift modulation strategy to calculate the secondary pulsating current: Where, is the secondary pulsating current, is the DC side current component, is the internal resistance of the battery; Through common mode inductors Together with the DC side voltage stabilizing capacitor C1, an LC passive filter is formed to suppress the secondary pulsating current. The secondary pulsating current after passing through the LC passive filter is: At this time, it becomes a second-order oscillation system, which suppresses the secondary pulsating current to a certain extent in a short time.

5. The DC-DC-based high-voltage direct-mounted energy storage system according to claim 4, characterized in that: The working modes of the current stabilization unit are: boost mode and buck mode; Battery power generation: In boost mode, only cascaded DC-DC converter G12 and cascaded DC-DC converter G14 are working; in buck mode, only cascaded DC-DC converter G11 and cascaded DC-DC converter G13 are working; Battery charging: In boost mode, only cascaded DC-DC converter G11 and cascaded DC-DC converter G13 work; in buck mode, only cascaded DC-DC converter G12 and cascaded DC-DC converter G14 work.

6. The DC-DC-based high-voltage direct-mounted energy storage system according to claim 5, characterized in that: In the boost mode, the cascaded DC-DC converter G11 is turned on. At this time, the cascaded DC-DC converter G12 and the cascaded DC-DC converter G14 are controlled by the modulation signal to increase the voltage output to the power module. The expression of the voltage output to the power module is: Where, , , is the input side voltage, is the voltage output to the power module, is the inductor current. According to the volt-second balance theory, we get: 。 7. The DC-DC-based high-voltage direct-mounted energy storage system according to claim 6, characterized in that: The system also includes: an AC isolating switch S1, a soft start switch S2, a reactor L1, and a soft start resistor R1; The soft start switch S2 is connected in series with the soft start resistor R1; The first end of the soft start switch S2 and the first end of the AC isolation switch S1 are connected to the medium and high voltage power grid; The second end of the soft start switch S2 is connected to the first end of the soft start resistor R1; The second end of the soft-start resistor R1 and the second end of the AC isolating switch S1 are connected to the first end of the reactor L1; The second end of the reactor L1 is connected to the upper output end of the power module.

8. A control method for a DC-DC-based high-voltage direct-mounted energy storage system according to any one of claims 1 to 7, characterized in that: The method comprises: Step S1: Estimate the SOC status of the battery pack. When the SOC status of the battery pack is less than or equal to 20% power, execute step S2; otherwise, execute step S3; Step S2: No discharge is performed, an early warning is issued, and other battery packs are coordinated to discharge, and the process returns to step S1; Step S3: setting the output voltage of the DC-DC converter and selecting the operating mode according to the fluctuation of the grid voltage; Step S4: increasing or decreasing the voltage output to the power module based on the selected operating mode; Step S5: Calculate whether to increase or decrease the voltage output to the power module; Step S6: Determine whether the voltage difference between the voltage output to the power module and the grid voltage is less than 5% of the grid voltage. If so, end the process; otherwise, return to step S3.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the method according to claim 8 are implemented.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to claim 8 are implemented.

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