Reconfigurable bipolar switchable energy storage system and control method thereof

Abstract

The invention relates to the technical field of flexible direct current power transmission, in particular to a reconfigurable bipolar switchable energy storage system and a control method thereof, and the system comprises an energy storage unit which comprises a battery; the input end of the energy conversion unit is connected to the energy storage unit, and the energy conversion unit is used for converting the stored energy into bidirectional direct-current electric energy; the input end of the polarity switching unit is connected to the output end of the energy conversion unit, and the polarity switching unit is used for switching the voltage polarity of the output port; and the control unit is used for respectively sending driving signals to the energy conversion unit and the polarity switching unit. According to the invention, the problem that the switching between the positive voltage output and the negative voltage output is completed according to the surplus or vacancy condition of the direct current side power in the large-scale renewable energy access power grid is effectively solved, and the rapid charging and discharging control of the energy storage system is realized, so that the direct current side power fluctuation is effectively stabilized, and the stability of the voltages at the two ends of the MMC is rapidly maintained.

Description

Technical Field

[0001] This invention relates to the field of flexible DC transmission technology, and in particular to a reconfigurable bipolar switchable energy storage system and its control method. Background Technology

[0002] In DC grid systems centered on modular multilevel converters (MMCs), the intermittent output of large-scale renewable energy sources often leads to drastic power fluctuations on the DC side. When the instantaneous power generation of distributed sources such as photovoltaics and wind power exceeds the load demand, a power surplus occurs on the DC bus, causing a sharp voltage rise; conversely, a power deficit leads to a sharp voltage drop. To maintain system stability, energy storage units are needed to rapidly absorb or release energy to smooth out these fluctuations. Existing technologies mainly rely on two approaches: one is to use multi-port DC-DC converters to connect the positive and negative bus energy storage batteries separately, with a central controller coordinating charging and discharging; the other is to add an external polarity conversion circuit between the energy storage unit and the DC bus, with a centralized energy management system regulating the power flow.

[0003] However, such solutions have significant drawbacks. Multi-port architectures require independent converters for batteries of different polarities, leading to a significant increase in hardware costs and complex control logic. External polarity conversion circuits introduce additional switching losses, reducing system efficiency. More critically, centralized decision-making relies on remote communication to transmit voltage detection signals and drive commands; during power surges, communication delays cause response lags, failing to meet the millisecond-level voltage transient stability control requirements of the MMC. Furthermore, existing topologies struggle to adapt to the plug-and-play functionality of heterogeneous batteries, forcing the system to add a DC-AC inverter stage for voltage adaptation, further sacrificing response speed and energy efficiency. These shortcomings severely restrict the stability and economic viability of DC grids in scenarios with a high proportion of renewable energy.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] This invention provides a reconfigurable bipolar switchable energy storage system and its control method, which can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A reconfigurable bipolar switchable energy storage system, the system comprising: Energy storage units, including batteries; An energy conversion unit, the input of which is connected to the energy storage unit, is used to convert the stored energy in the energy storage unit into bidirectional direct current energy; A polarity switching unit, the input terminal of which is connected to the output terminal of the energy conversion unit, is used to switch the voltage polarity of the output port; The control unit sends drive signals to the energy conversion unit and the polarity switching unit respectively; The energy conversion unit is configured to selectively output a positive or negative voltage to the polarity switching unit in response to the drive signal. The polarity switching unit is configured to map the positive or negative voltage to the same set of output ports based on the drive signal.

[0007] Furthermore, the polarity switching unit includes a first switching transistor and a second switching transistor connected in series; The collector of the first switching transistor is connected to the first port; The emitter of the second switch is connected to the second port and the negative terminal of the output. The emitter of the first switch and the collector of the second switch are connected at the positive input terminal.

[0008] Furthermore, the cathode of the body diode of the first switching transistor faces the first port, and the anode faces the positive terminal of the input terminal; The cathode of the body diode of the second switching transistor faces the positive terminal of the input terminal, and the anode faces the second port; The body diode is configured to provide a freewheeling path when the corresponding switch is turned off.

[0009] Furthermore, when the voltage at the first port is lower than the voltage at the positive terminal of the input, the body diode of the first switch is turned on to form a first freewheeling path, and the current flows from the positive terminal of the input through the body diode of the first switch to the first port; When the voltage at the second port is higher than the voltage at the positive terminal of the input terminal, the body diode of the second switch is turned on to form a second freewheeling path, and the current flows from the positive terminal of the input terminal through the body diode of the second switch to the second port.

[0010] Furthermore, the energy conversion unit includes: The first inductor is connected between the positive terminal of the energy storage unit and the first capacitor; The first power switch has its emitter connected to the negative terminal of the energy storage unit; The emitter of the second power switch is connected to the collector of the first power switch. The diode has its cathode connected to the negative terminal of the energy storage unit; The first capacitor is connected between the collector of the first power switch and the anode of the diode; The second inductor is connected between the anode of the diode and the second capacitor; The second capacitor is connected between the second inductor and the negative terminal of the energy storage unit, and is connected in parallel with the first output resistor; The third capacitor is connected between the negative terminal of the energy storage unit and the collector of the second power switch, and is connected in parallel with the second output resistor.

[0011] Furthermore, when operating in discharge mode, the second switch is turned on to form a discharge circuit, and the first switch is turned off to block the charging circuit. The first power switch is driven to conduct, causing the energy conversion unit to output a negative voltage; The second port is electrically connected to the second switching port, the first port is electrically connected to the first switching port, and the positive terminal of the second capacitor is connected to the first switching port; The third capacitor is connected to the circuit through the first power switch that is turned on to maintain negative voltage output.

[0012] Furthermore, when operating in charging mode, the first switch is turned on to establish an external power supply path, and the second switch is turned off to block the discharge circuit. The first port is electrically connected to the third switching port, and the second port is electrically connected to the second switching port, so that the external power supply current is injected into the negative terminal of the third capacitor from the first port; The first power switch and the second power switch operate in reverse boost mode to output positive voltage, and transfer the input current of the third capacitor to the positive terminal of the energy storage unit through the energy conversion unit.

[0013] Furthermore, the control unit is configured to: Real-time monitoring of DC-side bus voltage; When the DC side power deficit voltage drops, a discharge mode drive signal is generated to control the energy conversion unit to output a negative polarity voltage and drive the polarity switching unit to map the negative voltage to the second port. When the DC side power surplus voltage rises, a charging mode drive signal is generated to control the energy conversion unit to output a positive voltage and drive the polarity switching unit to map the positive voltage to the first port. At this time, the drive signal of the first power switch and the drive signal of the second power switch are complementary without ignoring the dead time.

[0014] Furthermore, when the system is in a power surplus state and the DC bus voltage is higher than the battery voltage, the drive signals of the first power switch and the second power switch are complementary without considering the dead time.

[0015] A control method for a reconfigurable bipolar switchable energy storage system, the method comprising: The control unit monitors the DC bus voltage on the input side and the battery voltage on the output side in real time. When the DC bus voltage is greater than the battery voltage, charging control is executed: The energy conversion unit is controlled to construct a step-down topology path, the polarity switching unit is controlled to lock the first polarity output, and the energy storage unit stores the energy on the input side during the switching on phase and releases the energy to the output side during the switching off phase. When the battery voltage is greater than the DC bus voltage, discharge control is executed: The energy conversion unit is controlled to construct a boost topology path, the polarity switching unit is controlled to switch to the second polarity output, and the energy storage unit stores the energy on the output side during the switch-on phase and releases the energy to the input side during the switch-off phase.

[0016] The technical solution of this invention can achieve the following technical effects: It effectively solves the problem of switching between positive and negative voltage output based on the surplus or deficit of DC power in large-scale renewable energy grid integration, realizes rapid charging and discharging control of energy storage system, thereby effectively smoothing DC power fluctuations and quickly maintaining the stability of voltage across MMC.

[0017] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a circuit topology diagram of a reconfigurable bipolar switchable energy storage system; Figure 2 This is a schematic diagram of the port being turned on in discharge mode; Figure 3 A schematic diagram showing the port being connected in charging mode; Reference numerals: V+, positive input terminal; V-, negative output terminal; S3, first switching transistor; S4, second switching transistor; S5, first power switching transistor; S6, second power switching transistor; L1, first inductor; L2, second inductor; C1, first capacitor; C2, second capacitor; C3, third capacitor; R1, first output resistor; R2, second output resistor; D, diode; Port 1, first port; Port 2, second port; Port A, first switching port; Port B, second switching port; Port C, third switching port. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Example 1; like Figure 1 As shown, this application provides a reconfigurable bipolar switchable energy storage system, the system comprising: Energy storage units, including batteries; An energy conversion unit, the input of which is connected to an energy storage unit, is used to convert the stored energy in the energy storage unit into bidirectional DC power. The polarity switching unit has its input terminal connected to the output terminal of the energy conversion unit and is used to switch the voltage polarity of the output port. The control unit sends drive signals to the energy conversion unit and the polarity switching unit respectively; The energy conversion unit is configured to respond to and drive signals, selectively outputting positive or negative voltage to the polarity switching unit; The polarity switching unit is configured to map positive or negative voltages to the same set of output ports based on the drive signal.

[0023] Specifically, the reconfigurable bipolar switchable energy storage system mainly comprises four core components: an energy storage unit, an energy conversion unit, a polarity switching unit, and a control unit. These units are interconnected through electrical connections and control signals, achieving functional synergy and flexibly adapting to energy storage and bipolar output requirements. Firstly, the energy storage unit utilizes common battery types, such as lithium-ion battery packs, lead-acid battery packs, or other types of battery modules. This module can be configured with a fixed capacity based on user needs, or its capacity can be expanded through modular design. The primary function of the energy storage unit is to perform energy storage tasks and provide power for subsequent power transmission and conversion. In this preferred embodiment, a lithium-ion battery is selected. The lithium-ion battery pack, as an energy storage unit, has a nominal voltage of 48V and is equipped with protection circuits and a voltage monitoring module to ensure safe and reliable operation of the energy storage. Secondly, the energy conversion unit is designed to convert energy using a high-efficiency bidirectional DC-DC converter. The input of this bidirectional converter is connected to the energy storage unit, and its output can provide either a positive or negative voltage. Its bidirectional nature allows electrical energy to be both stored in the battery and released from the battery to an external load. In this preferred embodiment, the unit employs a bidirectional buck-boost converter circuit based on pulse width modulation control. The polarity and amplitude of the output voltage are controlled by adjusting the duty cycle of the modulation wave. Simultaneously, a redundant protection mechanism is configured in the hardware circuit to prevent power outages at the load end. In the event of a short circuit or overload, this unit can quickly disconnect the output circuit to protect the energy storage unit from damage. The input terminal of the polarity switching unit is connected to the output terminal of the energy conversion unit. Its main function is to switch the voltage polarity of the output port after receiving a control signal, and always maintain a unified output port. Specifically, this unit can achieve positive and negative voltage polarity switching through an electronic switching network, such as a group of MOSFETs or IGBT devices, and map them to the same group of output ports to ensure that the output voltage direction is consistent with the control signal. In this preferred embodiment, the polarity switching unit is composed of a MOSFET array with high response speed and equipped with a reverse diode to prevent backflow of power, further improving the unit's performance. Reliability; The control unit is the core coordination module of the system. This module sends drive signals to the energy conversion unit and polarity switching unit respectively through internal logic circuits or microcontroller instructions to achieve bipolar voltage output. The control unit monitors parameters such as battery voltage and temperature in real time, and generates control signals based on the monitoring information and external input instructions. In the preferred embodiment, the control unit communicates serially with the sensor devices. Combined with PID algorithm and preset control strategy, it can adjust the working state of each unit in real time and accurately. To further illustrate this with a specific example: In practical applications, assuming that the energy storage unit uses a 240Ah lithium battery pack, the user wants to provide voltage to the bipolar load through the polarity switching function.In the initial state, the control unit sets the energy conversion unit to output a positive voltage. The polarity switching unit maps this positive voltage to the same set of output ports, and the load starts to work. When it is necessary to switch the polarity to achieve negative voltage operation, the control unit calculates the corresponding switching strategy and sends a polarity adjustment signal to the energy conversion unit, while notifying the polarity switching unit to change the polarity direction of the output port. Furthermore, an anti-interference circuit can be added to the polarity switching unit to reduce instantaneous voltage fluctuations caused by inductive effects during switching. The control unit's software algorithm can also incorporate learning capabilities to predict energy loss during each switching process based on historical data, so as to dynamically adjust the safety margin of the energy conversion unit.

[0024] The technical solution of this invention effectively solves the problem of switching between positive and negative voltage output based on the surplus or deficit of DC power in large-scale renewable energy grid integration, realizing rapid charging and discharging control of energy storage system, thereby effectively smoothing DC power fluctuations and quickly maintaining the stability of voltage across MMC.

[0025] Furthermore, the polarity switching unit includes a first switching transistor and a second switching transistor connected in series; The collector of the first switching transistor is connected to the first port; The emitter of the second switch is connected to the second port and the negative terminal of the output. The emitter of the first switching transistor and the collector of the second switching transistor are connected at the positive terminal of the input.

[0026] As a preferred embodiment of the above, the polarity switching unit is designed to achieve fast, accurate, and safe voltage polarity switching, thereby meeting the usage requirements under different load conditions. The polarity switching unit consists of a first switching transistor and a second switching transistor connected in series, which respectively control the current on / off state and regulate the polarity output. The first and second switching transistors are preferably metal-oxide-semiconductor field-effect transistors (MOSFETs) because MOSFETs have the characteristics of fast switching speed, low on-resistance, and low drive power, making them suitable for high-frequency operation and low-loss requirements. Specifically, the collector of the first switching transistor is connected to the first port, which is the main input terminal of the circuit. It receives the voltage signal from the energy conversion unit through an external circuit. The emitter of the first switching transistor is directly connected to the collector of the second switching transistor. This connection point constitutes the current path node of the polarity switching unit. The emitter of the second switching transistor is connected to the second port through a wire, and also serves as the main output negative terminal of the polarity switching unit. In this preferred embodiment, the polarity switching unit... The working principle is as follows: when the control electrode of the first switch receives a control signal, it is adjusted to the on state. At this time, current flows into the first switch from the first port and is introduced into the second switch through the emitter of the first switch, i.e., the current path node. Through the control electrode signal of the second switch, the second switch is also adjusted to the on state, thus forming a conductive path from the first port to the second port. Due to the series connection of the first and second switches, the current path and voltage polarity of the entire circuit are determined by the on and off states of both. The advantage of the polarity switching unit is that it can achieve fast and flexible polarity switching through control signals. When it is necessary to change the voltage polarity of the output terminal, the control unit can send corresponding command signals to the first and second switches simultaneously. For example, when a positive voltage needs to be output, it is only necessary to turn on the first switch and adjust the second switch to the off state. Conversely, when a negative voltage needs to be output, the operating states of the first and second switches can be adjusted in reverse so that the current flows out in the opposite polarity.

[0027] Furthermore, the cathode of the body diode of the first switching transistor faces the first port, and the anode faces the positive terminal of the input. The cathode of the body diode of the second switching transistor faces the positive terminal of the input, and the anode faces the second port; The body diode is configured to provide a freewheeling path when the corresponding switch is turned off.

[0028] As a preferred embodiment of the above, the cathode of the body diode of the first switching transistor is connected to the first port, and its anode is connected to the positive input terminal. This connection ensures that when the first switching transistor is in the off state, its body diode can be activated, allowing current to flow from the positive input terminal to the first port, thereby forming a complete freewheeling path. In bipolar switchable energy storage systems, since voltage polarity switching usually involves frequent switching operations, this process may lead to transient reverse current or voltage spikes. The body diode of the first switching transistor can effectively eliminate these sudden problems. The anode of the body diode of the second switching transistor is connected to the second port, and its cathode is connected to the positive input terminal. For example, when the second switching transistor is in the off state, the body diode provides a freewheeling path. This circuit path allows current to flow from the second port to the positive input terminal, avoiding voltage fluctuations caused by circuit disconnection. Especially when abnormal situations occur during polarity switching or at the load end, such as when the load inductive element releases reverse current, the body diode of the second switching transistor can achieve freewheeling. Effective freewheeling is achieved to protect the system circuit and related components. When the first switch is switched to the off state, the current cannot continue to flow through the off switch due to the reverse current released by the inductor at the load end. At this time, the body diode of the first switch is energized, and its anode receives the current released by the inductor and delivers it to the first port through the cathode, completing the freewheeling path. This avoids the impact on the circuit caused by the sudden reverse current of the load inductive element. Similarly, when the second switch needs to be switched to the off state, its body diode is also energized synchronously, forming a similar freewheeling path. In addition, to ensure that the freewheeling function of the body diode can always respond in a timely manner during the switching process, in this embodiment, the control unit is designed to monitor the circuit current flow and voltage value in real time, and dynamically adjust the turn-off sequence of the switch based on the detection data. For example, when a reverse current is detected from the inductive element at the load end, the control unit will slightly delay the turn-off time of the first or second switch to ensure that the body diode can be correctly energized and complete the freewheeling.

[0029] Furthermore, when the voltage at the first port is lower than the voltage at the positive input terminal, the body diode of the first switch turns on to form the first freewheeling path, and the current flows from the positive input terminal through the body diode of the first switch to the first port. When the voltage at the second port is higher than the voltage at the positive terminal of the input, the body diode of the second switch turns on to form a second freewheeling path, and the current flows from the positive terminal of the input through the body diode of the second switch to the second port.

[0030] As a preferred embodiment of the above, in the specific implementation process, the operation of the first port is first considered. When the voltage of the first port is lower than the positive voltage of the input terminal, the body diode of the first switch automatically turns on, forming a low-impedance path. This preferred design allows the current at the positive terminal of the input terminal to flow directly into the first port through the body diode of the first switch without having to pass through the high-impedance traditional switching path, ensuring that the current can reach the first port quickly and effectively. This design not only simplifies the current path but also reduces losses and improves system efficiency. For example, assuming that during the operation of the energy storage system, the voltage of the first port of the battery pack is lower than that of the input terminal, the current at the input terminal can flow steadily into the first port due to the conduction of the body diode, thereby effectively charging the battery. When the voltage of the second port is higher than the positive voltage of the input terminal, the body diode of the second switch turns on, forming a second freewheeling path. This freewheeling path is similar to... The design of the first port aims to ensure that the positive current at the input terminal can flow smoothly into the second port when the voltage is higher. A preferred approach is to utilize the body diode characteristics of the second switching transistor to provide a stable current supply to the high-voltage port. For example, when the positive voltage of the charger is lower than the voltage at the second port of the energy storage device, the body diode conducts, allowing current to flow effectively into the second port even when the charger is in a low-power state. In implementation, high-quality semiconductor materials are used to construct the switching transistor to reduce on-resistance and improve diode conduction efficiency. To ensure system safety and reliability, overvoltage and undervoltage protection mechanisms are employed to monitor and regulate the current flow path. Furthermore, to further optimize energy management, it is recommended to integrate an intelligent controller to monitor and regulate the voltage and current flow at each port in real time. This not only improves the system's adaptability but also ensures stable operation under different operating conditions.

[0031] Furthermore, the energy conversion unit includes: The first inductor is connected between the positive terminal of the energy storage unit and the first capacitor; The first power switch has its emitter connected to the negative terminal of the energy storage unit; The emitter of the second power switch is connected to the collector of the first power switch. A diode, with its cathode connected to the negative terminal of an energy storage unit; The first capacitor is connected between the collector of the first power switch and the anode of the diode. The second inductor is connected between the anode of the diode and the second capacitor; The second capacitor is connected between the second inductor and the negative terminal of the energy storage unit, and is connected in parallel with the first output resistor; The third capacitor is connected between the negative terminal of the energy storage unit and the collector of the second power switch, and is connected in parallel with the second output resistor.

[0032] In a preferred embodiment, the first inductor is connected in series between the positive terminal of the energy storage unit and the first capacitor. Its function is to smooth the current flowing from the energy storage unit to the first capacitor, ensuring that the impact of current fluctuations on energy transfer efficiency is minimized. By optimizing the parameters of the first inductor, including inductance value and wire selection, losses during energy transfer can be effectively reduced, thereby improving overall energy storage efficiency. The emitter of the first power switch is directly connected to the negative terminal of the energy storage unit, and its collector is connected to the anode of the diode through the first capacitor. The first power switch carries the main switching task of the system, and the dynamic switching of the circuit is achieved by changing the drive control signal. This design enables the energy storage system to efficiently perform energy transfer operations in both charging and discharging modes, avoiding unnecessary energy loss. The emitter of the second power switch is connected to the first capacitor. The collectors of the switching transistors are connected, and their collectors are further connected to the third capacitor and the negative terminal of the energy storage unit. This layout design provides a more flexible energy switching path and optimizes the stability of the bipolar operation of the system. It is preferable to use bipolar switching devices, which can more accurately handle the power flow of the bipolar energy storage system. The cathode of the diode is directly connected to the negative terminal of the energy storage unit, while the anode is connected to the second capacitor through the second inductor. Its key function is to provide unidirectional protection during energy transmission to avoid backflow affecting the system function. The diode should be selected based on its voltage withstand and conduction performance, prioritizing high-efficiency components to ensure stable performance under high power conditions. The first capacitor, second capacitor, and third capacitor optimize the response efficiency at different stages of the energy flow process in the entire circuit. The first capacitor is used to store high-frequency energy for rapid release or absorption. The second and third capacitors serve as voltage regulators associated with the second inductor and the second power switch, respectively, effectively balancing voltage fluctuations during energy storage. The second inductor, connected between the diode anode and the second capacitor, optimizes the current frequency characteristics during system discharge and filters out noise in the current path, thereby improving energy conversion efficiency. The preferred parameters of the second inductor can be adjusted according to specific design requirements to meet the dynamic response requirements of the energy storage system during rapid charging and discharging. The first output resistor is connected in parallel with the second capacitor, and the second output resistor is connected in parallel with the third capacitor. These designs further optimize the stability of power transfer between components. The parallel resistors can eliminate local voltage fluctuations in the dynamic circuit, ensuring that the system is not affected by instantaneous disturbances when switching between bipolar charging and discharging modes.

[0033] Furthermore, such as Figure 2 As shown, when operating in discharge mode, the second switch is turned on to form a discharge circuit, and the first switch is turned off to block the charging circuit. The first power switch is driven to conduct, causing the energy conversion unit to output a negative voltage; The second port is electrically connected to the second switching port, the first port is electrically connected to the first switching port, and the positive terminal of the second capacitor is connected to the first switching port. The third capacitor is connected to the circuit through the first power switch to maintain negative voltage output.

[0034] As a preferred embodiment of the above embodiments, when the energy storage system operates in discharge mode, the second power switch is in the on state, forming a low-impedance path between its emitter and collector, allowing the stored energy of the energy storage unit to be effectively released through the circuit. At this time, the first power switch is in the off state to ensure that there is no unnecessary energy flow in the charging circuit, thereby concentrating the system energy output on the discharge path. Preferably, a second power switch with high withstand voltage and low internal resistance is used to improve discharge efficiency and ensure system stability. In discharge mode, the first power switch is driven to conduct for a short time, its function being to achieve negative voltage output. By combining the charging and discharging characteristics of the first capacitor and the negative voltage maintenance capability of the third capacitor, the system can stably output negative voltage to meet the negative polarity input requirements of the external load. In a preferred embodiment, the drive signal of the first power switch can be implemented by a specially designed pulse width modulation circuit to ensure accurate drive signal and stable negative voltage output. In discharge mode, the system ports are configured such that the second port is electrically connected to the second switching port, and the first port is electrically connected to the first switching port. This port connection method optimizes the energy flow path, ensuring that the energy release and storage of each capacitor meet design requirements. The positive terminal of the second capacitor is connected to the first switching port, serving as part of the voltage source and providing a stable output voltage. In this preferred embodiment, the port connection status can be automatically adjusted by controlling the electrical switching of the ports via a chip, facilitating switching between different operating modes. The third capacitor is connected to the circuit through the first power switch, and its main function is to maintain negative voltage output, ensuring voltage stability during dynamic discharge. To ensure negative voltage regulation capability, the capacitance and electrical performance parameters of the third capacitor should be determined according to the system design. The capacity of the capacitor should be preferably within a suitable range to absorb sudden current changes and provide a stable negative voltage output. In some application scenarios, multiple third capacitors can be used in parallel to enhance stability. In the drive logic design, when the system receives an external discharge command, the control unit will select to turn on the second power switch and turn off the first power switch by running the energy storage management algorithm. Then, it will drive the first power switch to conduct for a short time, so that the energy conversion unit can achieve negative voltage output. The negative voltage of its main circuit is maintained by the third capacitor. At the same time, combined with the change of port connection state, it ensures that the positive terminal of the second capacitor continuously provides power to the first switching port.

[0035] Furthermore, such as Figure 3 As shown, when operating in charging mode, the first switch is turned on to establish an external power supply path, and the second switch is turned off to block the discharge circuit. The first port is electrically connected to the third switching port, and the second port is electrically connected to the second switching port, so that the external power supply current is injected into the negative terminal of the third capacitor from the first port; The first and second power switches operate in reverse boost mode to output positive voltage, transferring the input current of the third capacitor to the positive terminal of the energy storage unit via the energy conversion unit.

[0036] As a preferred embodiment of the above, in charging mode, the first power switch establishes an external power supply path by being turned on, allowing the external power supply current to smoothly enter the system. This design eliminates the need for additional switching devices, and by appropriately controlling the turn-off of the second power switch, the discharge circuit is isolated, ensuring that the energy flow is correctly directed to the positive terminal of the energy storage. It is preferable to use a switch with fast response and strong current interruption capability to ensure efficient operation in this mode. During charging, the first port is connected to the third switching port, and the second port is connected to the second switching port. This port configuration ensures that the negative terminal of the third capacitor directly receives the input current of the external power supply, providing a low-impedance path to reduce power loss. It is preferable to consider electromagnetic compatibility during the design process to ensure the stability and reliability of the port connection. The external power supply current is injected into the negative terminal of the third capacitor, laying the foundation for energy transfer to the positive terminal of the internal energy storage unit of the system. The third capacitor has low equivalent series resistance, which can reduce energy loss caused by conversion in fast charging mode and improve the quality of input energy by smoothing input current spikes. In reverse boost mode, the first and second power switches work together to output positive voltage. This is achieved by periodically alternating on and off, so that the current stored in the third capacitor can be stably delivered to the positive terminal of the energy storage unit after boost conversion. This boost process requires precise control logic, usually implemented through a high-frequency switching strategy to minimize energy loss and optimize power conversion efficiency. The energy conversion unit is responsible for boosting the external input current and finally delivering it to the positive terminal of the energy storage unit. Its design needs to consider elements that improve conversion efficiency and reduce losses, such as inductors, switches, and capacitors, and optimize parameters. For example, by using power components with low internal resistance and high efficiency and boost ratio parameters that meet the application requirements, the system can achieve robust charging management.

[0037] Furthermore, the control unit is configured as follows: Real-time monitoring of DC-side bus voltage; When the DC side power deficit voltage drops, a discharge mode drive signal is generated to control the energy conversion unit to output a negative polarity voltage and drive the polarity switching unit to map the negative voltage to the second port. When the DC side power surplus voltage rises, a charging mode drive signal is generated to control the energy conversion unit to output a positive voltage and drive the polarity switching unit to map the positive voltage to the first port. At this time, the drive signal of the first power switch and the drive signal of the second power switch are complementary without ignoring the dead time.

[0038] As a preferred embodiment of the above, the control unit acquires DC bus voltage data in real time through a high-precision ADC or voltage monitoring chip. This component not only has a fast response capability but also high accuracy to ensure that voltage changes can be captured in a timely manner. In the preferred configuration, the resolution and sampling rate of the ADC should match the rate of change of the system voltage to ensure that each voltage fluctuation is accurately monitored. When insufficient DC power is detected, causing a voltage drop, the control unit generates a discharge mode drive signal to control the energy conversion unit to output a negative polarity voltage. At this time, the polarity switching unit is driven to map the negative voltage energy to the second port. This design ensures a fast response to load demands under low voltage conditions and provides a stable negative polarity power supply to the load. In the preferred design, the control unit can be equipped with an intelligent algorithm to ensure that the drive signal adapts to the load voltage requirements. When a DC-side power surplus is detected, causing the voltage to rise, the control unit switches to charging mode, generates a drive signal to control the energy conversion unit to output a positive voltage, and drives the polarity switching unit to map the positive voltage to the first port. In this mode, the control unit strategy ensures that the drive signals of the first and second power switches are complementary, thereby stabilizing the energy conversion during the boost process and minimizing the impact of dead time on system efficiency. In the complementary drive design that ignores dead time, the first and second power switches need to be turned on alternately to ensure seamless switching of energy modes. The control unit needs to consider the on-time and off-time of each switch during the design, and achieve this complementary process by adjusting the phase difference of the drive signal to ensure maximum energy conversion efficiency. The polarity switching unit is responsible for mapping the polarity of the output voltage to the corresponding port according to the indication of the drive signal. Its design should comprehensively consider the fast response capability under different loads to ensure that both negative and positive voltages can be accurately delivered to the designated port.

[0039] Furthermore, when the system is in a power surplus state and the DC bus voltage is higher than the battery voltage, the drive signals of the first power switch and the second power switch are complementary, ignoring the dead time.

[0040] As a preferred embodiment of the above, the control unit monitors the DC bus voltage and battery voltage in real time. In a power surplus state, the bus voltage typically rises due to power overflow, while the battery voltage remains relatively low. At this time, the system enters a power conversion mode. When the bus voltage is higher than the battery voltage, the control unit sends an adjustment signal to initiate the complementary drive of the first and second power switches. In this operating mode, the first and second power switches operate through complementary drive signals. Ignoring dead time, the two power switches alternately turn on and off, ensuring efficient energy flow in the circuit. This complementary drive mode maximizes the system's energy conversion efficiency and reduces dynamic power loss caused by drive signal delay or inaccuracy. In a preferred embodiment, the drive signal is generated by a high-frequency pulse width modulation algorithm of the control unit, ensuring constant energy output by adjusting the duty cycle. In a power surplus state, the bus voltage is adjusted through the operation of the first power switch... The energy flows into the energy conversion unit via a path, and then through the second power switch to the positive terminal of the battery. This energy flow process is ensured to be smooth with zero interference by the complementarity of the drive signals. In the preferred case, the conduction time of each power switch needs to take into account the difference between the bus voltage and the battery voltage to avoid the instability caused by current surges. Since the dead time needs to be ignored in this technical solution, the phase difference of the drive signals of the two power switches is precisely controlled to maintain the complementary relationship between the two power switches and avoid power interruption caused by conduction gap. In the preferred case, the phase control of the drive signal is achieved by digital signal processing to ensure the fast response and dynamic adjustment capability of the signal output. Through the complementary drive design that ignores the dead time, the system achieves fast conversion between the bus voltage and the battery voltage and efficient power management. Compared with the traditional design, this technical solution significantly improves the energy conversion efficiency and reduces the loss during dynamic power transmission. The response time and stability of the system are significantly enhanced.

[0041] Example 2; Based on the same inventive concept as the reconfigurable bipolar switchable energy storage system in the foregoing embodiments, the present invention also provides a control method for a reconfigurable bipolar switchable energy storage system, the method comprising: The control unit monitors the DC bus voltage on the input side and the battery voltage on the output side in real time. When the DC bus voltage is greater than the battery voltage, charging control is activated: The control energy conversion unit constructs a step-down topology path, the control polarity switching unit locks the first polarity output, and the energy storage unit stores the energy on the input side during the switching on phase and releases the energy to the output side during the switching off phase. When the battery voltage is greater than the DC bus voltage, discharge control is executed: The control energy conversion unit constructs a boost topology path, the control polarity switching unit switches to the second polarity output, and the energy storage unit stores the energy on the output side during the switching on phase and releases the energy to the input side during the switching off phase.

[0042] Specifically, a high-precision voltage sensor or ADC transmits real-time data of the input-side DC bus voltage and the output-side battery voltage to the control unit. The control unit uses this data to determine whether charging control is triggered when the bus voltage is higher than the battery voltage, and vice versa. When charging mode is initiated, the energy conversion unit constructs a buck topology path to reduce the bus voltage and store it in the battery. During the switching-on phase, energy is transferred from the bus to the energy storage unit. During the switching-off phase, the energy in the storage unit is released to the battery, and the polarity switching unit locks the first polarity output at this time to ensure that the voltage is always accurately delivered to the positive terminal of the battery. In a preferred embodiment, the buck topology path uses a high-efficiency DC-DC converter. To minimize energy loss and improve conversion speed, when the battery voltage is higher than the bus voltage, the control unit initiates a discharge mode. The energy conversion unit constructs a boost topology path, increasing the battery's output voltage to support the bus demand. During the switching-on phase, the energy storage unit draws energy from the battery; during the switching-off phase, the energy is released to the bus, and the polarity switching unit switches to the second polarity output, ensuring that the boosted energy flow timely supports the bus voltage demand. In the preferred configuration, a fast-response switching transistor should be used to ensure that the discharge process can adapt to dynamic load changes. To achieve dynamic polarity adjustment, the polarity switching unit is designed to quickly change the output polarity, ensuring accurate voltage polarity during switching between charging and discharging. In the preferred case, an intelligent switching chip combined with logic control circuitry is used to ensure stability and fast response during polarity conversion.

[0043] The control method described above in this invention can effectively realize a reconfigurable bipolar switchable energy storage system, and the technical effects it can achieve are as described in the above embodiments, which will not be repeated here.

[0044] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A reconfigurable bipolar switchable energy storage system, characterized in that, The system includes: Energy storage units, including batteries; An energy conversion unit, the input of which is connected to the energy storage unit, is used to convert the stored energy in the energy storage unit into bidirectional direct current energy; A polarity switching unit, the input terminal of which is connected to the output terminal of the energy conversion unit, is used to switch the voltage polarity of the output port; The control unit sends drive signals to the energy conversion unit and the polarity switching unit respectively; The energy conversion unit is configured to selectively output a positive or negative voltage to the polarity switching unit in response to the drive signal. The polarity switching unit is configured to map the positive or negative voltage to the same set of output ports based on the drive signal.

2. The reconfigurable bipolar switchable energy storage system according to claim 1, characterized in that, The polarity switching unit includes a first switching transistor and a second switching transistor connected in series. The collector of the first switching transistor is connected to the first port; The emitter of the second switch is connected to the second port and the negative terminal of the output. The emitter of the first switch and the collector of the second switch are connected at the positive input terminal.

3. The reconfigurable bipolar switchable energy storage system according to claim 2, characterized in that, The cathode of the body diode of the first switching transistor faces the first port, and the anode faces the positive terminal of the input terminal; The cathode of the body diode of the second switching transistor faces the positive terminal of the input terminal, and the anode faces the second port; The body diode is configured to provide a freewheeling path when the corresponding switch is turned off.

4. The reconfigurable bipolar switchable energy storage system according to claim 3, characterized in that, When the voltage at the first port is lower than the voltage at the positive terminal of the input, the body diode of the first switch is turned on to form a first freewheeling path, and the current flows from the positive terminal of the input through the body diode of the first switch to the first port. When the voltage at the second port is higher than the voltage at the positive terminal of the input terminal, the body diode of the second switch is turned on to form a second freewheeling path, and the current flows from the positive terminal of the input terminal through the body diode of the second switch to the second port.

5. The reconfigurable bipolar switchable energy storage system according to claim 1, characterized in that, The energy conversion unit includes: The first inductor is connected between the positive terminal of the energy storage unit and the first capacitor; The first power switch has its emitter connected to the negative terminal of the energy storage unit; The emitter of the second power switch is connected to the collector of the first power switch. The diode has its cathode connected to the negative terminal of the energy storage unit; The first capacitor is connected between the collector of the first power switch and the anode of the diode; The second inductor is connected between the anode of the diode and the second capacitor; The second capacitor is connected between the second inductor and the negative terminal of the energy storage unit, and is connected in parallel with the first output resistor; The third capacitor is connected between the negative terminal of the energy storage unit and the collector of the second power switch, and is connected in parallel with the second output resistor.

6. The reconfigurable bipolar switchable energy storage system according to claim 5, characterized in that, When operating in discharge mode, the second switch is turned on to form a discharge circuit, and the first switch is turned off to block the charging circuit. The first power switch is driven to conduct, causing the energy conversion unit to output a negative voltage; The second port is electrically connected to the second switching port, the first port is electrically connected to the first switching port, and the positive terminal of the second capacitor is connected to the first switching port; The third capacitor is connected to the circuit through the first power switch that is turned on to maintain negative voltage output.

7. The reconfigurable bipolar switchable energy storage system according to claim 5, characterized in that, When operating in charging mode, the first switch is turned on to establish an external power supply path, and the second switch is turned off to block the discharge circuit. The first port is electrically connected to the third switching port, and the second port is electrically connected to the second switching port, so that the external power supply current is injected into the negative terminal of the third capacitor from the first port; The first power switch and the second power switch operate in reverse boost mode to output positive voltage, and transfer the input current of the third capacitor to the positive terminal of the energy storage unit through the energy conversion unit.

8. The reconfigurable bipolar switchable energy storage system according to claim 1, characterized in that, The control unit is configured to: Real-time monitoring of DC-side bus voltage; When the DC side power deficit voltage drops, a discharge mode drive signal is generated to control the energy conversion unit to output a negative polarity voltage and drive the polarity switching unit to map the negative voltage to the second port. When the DC side power surplus voltage rises, a charging mode drive signal is generated to control the energy conversion unit to output a positive voltage and drive the polarity switching unit to map the positive voltage to the first port. At this time, the drive signal of the first power switch and the drive signal of the second power switch are complementary without ignoring the dead time.

9. The reconfigurable bipolar switchable energy storage system according to claim 4, characterized in that, When the system is in a power surplus state and the DC bus voltage is higher than the battery voltage, the drive signals of the first power switch and the second power switch are complementary, ignoring the dead time.

10. A control method for a reconfigurable bipolar switchable energy storage system, characterized in that, The method includes: The control unit monitors the DC bus voltage on the input side and the battery voltage on the output side in real time. When the DC bus voltage is greater than the battery voltage, charging control is executed: The energy conversion unit is controlled to construct a step-down topology path, the polarity switching unit is controlled to lock the first polarity output, and the energy storage unit stores the energy on the input side during the switching on phase and releases the energy to the output side during the switching off phase. When the battery voltage is greater than the DC bus voltage, discharge control is executed: The energy conversion unit is controlled to construct a boost topology path, the polarity switching unit is controlled to switch to the second polarity output, and the energy storage unit stores the energy on the output side during the switch-on phase and releases the energy to the input side during the switch-off phase.

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