A direct current stacking-based power load distribution system

Abstract

The application relates to the technical field of charging stations, in particular to a power load distribution system based on direct-current stacked storage, which comprises: a direct-current stacked storage energy battery comprising a plurality of battery modules; a plurality of switch devices are arranged, and each battery module is connected to a load bus through a corresponding switch device; a control device acquires the demand of the power load, controls the corresponding switch device to be closed according to the demand of the power load, so that the required number of battery modules are connected to the load bus; the control device is configured to: in response to the demand of the power load, control the switch device to connect at least one capacitor to the load bus and connect at least one battery module to the load bus, and gradually control the switch device according to the change of the charging current, and replace the capacitor connected to the load bus with the battery module. The technical scheme provided by the application significantly improves the dynamic response capability and operation stability of the system, and further provides higher charging current in practice.

Description

Technical Field

[0001] This application relates to the field of charging station technology, and more specifically, to a power load distribution system based on DC cascaded storage. Background Technology

[0002] The content in this section provides only background information related to this application and may not constitute prior art.

[0003] As a crucial urban infrastructure, electric vehicle charging stations primarily function to provide charging services for vehicles. Their system typically comprises a grid receiving module, a charging module, and a DC-DC energy storage module. The grid receiving module is responsible for obtaining electrical energy from the distribution network and converting the alternating current (AC) to direct current (DC). The charging module receives the DC power from the grid receiving module and distributes it to the various charging stations within the station. The DC-DC energy storage module acts as an energy storage unit, both supplying energy to the charging module to supplement the load on the grid receiving module and feeding energy back to the grid through the grid receiving module.

[0004] To increase charging speed, existing charging stations often require extremely high charging currents, but excessively high charging power can damage the electric vehicle's battery. Therefore, different users make different choices: some prefer high-power charging solutions, while others choose low-power solutions. This necessitates that charging modules be able to handle more variable loads. Simultaneously, to reduce grid dispatching pressure, charging stations strive to ensure that the power received by the grid receiving module from the distribution network is planned, and when load changes occur, the DC-DC power storage module makes corresponding adjustments.

[0005] When regulating current in a DC-DC cascade module, common control methods include insulated-gate bipolar transistor (IGBT) control and switching group control. IGBTs control the conduction level by adjusting the voltage signal applied to their gate (G), thereby controlling the current magnitude. However, this control method has limitations when dealing with large currents; when the current is high, the IGBT is easily damaged and cannot effectively control large currents.

[0006] Switch group control involves equipping each battery in the DC-DC cascaded storage module with a small switch, adjusting the current by controlling the number of batteries connected to the bus. However, in practical applications, this approach struggles to achieve rapid current control. Especially when the charging gun is first connected to the charging port, a surge current (impact current) much larger than the steady-state operating current is typically generated, causing damage to the battery's internal control components. Furthermore, the feedback rate of using small switches to control current is low; the current magnitude must be measured before the corresponding switch is closed, making timely adjustments based on instantaneous current magnitude impossible. Additionally, current control is discrete, dependent on the number of batteries connected to the load bus, making precise current control difficult.

[0007] In summary, existing ultra-high voltage charging stations still have shortcomings in current feedback regulation, and a charging management system capable of achieving rapid current feedback regulation has not yet been formed. Summary of the Invention

[0008] In view of this, the purpose of this application is to provide a power load distribution system based on DC cascading storage, which can solve the technical problems raised in the background art.

[0009] A power load distribution system based on DC superimposed storage includes:

[0010] DC stacked energy storage battery, comprising several battery modules;

[0011] Multiple switching devices are provided, and each battery module is connected to the load bus through a corresponding switching device.

[0012] The control device acquires the power load demand and controls the corresponding switching device to close according to the power load demand so that the required number of battery modules can be connected to the load bus.

[0013] The switching device includes:

[0014] Two paired switch assemblies, one of which has its input terminal connected to the battery module, and the other has its input terminal connected to a capacitor;

[0015] Control switch assembly to enable battery modules or capacitors to be connected to the load bus in either a forward or reverse manner;

[0016] When both the battery module and the capacitor are connected to the load bus in the forward direction, both the battery module and the capacitor provide a forward load to the load bus.

[0017] When both the battery module and the capacitor are connected to the load bus in reverse, both the battery module and the capacitor are used to absorb the load of the load bus.

[0018] When the battery module is connected to the load bus in the forward direction and the capacitor is connected to the load bus in the reverse direction, the battery module provides a positive load to the load bus, and the capacitor is used to absorb the load of the load bus.

[0019] When the battery module is connected to the load bus in reverse and the capacitor is connected to the load bus in forward, the battery module is used to absorb the load of the load bus, and the capacitor provides the forward load to the load bus.

[0020] The control device is configured to: respond to power load demand, control the switching device to connect at least one capacitor to the load bus and at least one battery module to the load bus, and gradually control the switching device to replace the capacitor connected to the load bus with the battery module according to the change of charging current.

[0021] This application configures a capacitor for each battery module and utilizes the fast charging and discharging response of capacitors. In the initial stage of responding to load demand and connecting the required number of battery modules and capacitors to the load bus, the capacitors provide current first. As the capacitors discharge (when connected in the forward direction), their terminal voltage changes significantly, and the current they contribute decreases rapidly. This process effectively offsets the surge current peak that may occur when the charging port is first connected to the load bus. At the same time, the control device gradually replaces the capacitors connected to the load bus with the corresponding battery modules according to the current changes. The battery modules provide stable and continuous voltage and current, thereby ultimately ensuring that the load bus receives a stable and continuous current supply. This significantly improves the dynamic response capability and operational stability of the system, and in practice, it can provide higher charging current to achieve high-speed charging.

[0022] Existing modular DC energy storage systems typically regulate the load bus voltage by simply increasing or decreasing the number of connected battery modules. This results in large, discrete step changes in the voltage output, leading to insufficient regulation accuracy and flexibility. To achieve more precise or diverse voltage outputs (such as values ​​between battery module voltages or specific combinations of voltages), additional DC / DC voltage conversion circuits are often required. This not only significantly increases the system's cost, size, and complexity but also introduces additional energy conversion losses, reducing overall efficiency.

[0023] Furthermore, each capacitor corresponds to only one battery module to form a combined functional unit;

[0024] The positive terminal of the capacitor is connected to the load bus through a set of switches, and the negative terminal of the capacitor is connected to the load bus through a set of switches.

[0025] The positive terminal of the battery module is connected to the load bus via a set of switches, and the negative terminal of the battery module is connected to the load bus via a set of switches.

[0026] This application achieves independent connection and flexible combination (e.g., individual output, series output, or parallel output) of power units (battery modules or capacitors) within a single combined functional unit by uniquely configuring a capacitor for each battery module and connecting the positive and negative terminals of both the capacitor and the battery module to the load bus through their respective independent sets of switches. This design greatly enriches the output voltage options and regulation capabilities of the load bus: when multiple combined functional units work together, by precisely controlling the connection method (individual or combined) and the number of battery modules and capacitors in each unit, a large number of different step (even nearly continuous) composite voltage values ​​can be generated over a wide range. This not only effectively overcomes the shortcomings of traditional solutions, such as large voltage regulation steps and poor flexibility, but also eliminates the need for complex DC / DC conversion circuits. Therefore, while significantly improving the precision, flexibility, and dynamic performance of the output voltage, it simplifies the structure, reduces costs, and improves energy utilization efficiency.

[0027] In existing modular battery systems, the switching structure connecting battery modules to the bus is typically quite simple, often only capable of two basic states: unidirectional connection (forward power supply) or complete disconnection. This structure limits the system's control over the battery cell connection method, preventing the implementation of reverse connection (for energy absorption) or more precise state switching. Especially in applications requiring battery cells to both provide and absorb energy (e.g., to handle load fluctuations or regenerative braking), or where rapid and flexible changes in cell connection polarity are needed to optimize system performance (e.g., combining with the aforementioned capacitors to achieve richer voltage outputs or dynamic responses), the single control mode of existing switching structures becomes a constraint on system flexibility and efficiency.

[0028] Furthermore, the switch group includes at least two switches, one of which has its output connected to the positive terminal of the load bus, and the other has its output connected to the negative terminal of the load bus.

[0029] This application incorporates two independent switches in each switching assembly, connected to the positive (positive) terminal and the output (negative) terminal of the load bus, respectively. This allows each switching assembly to control its connected power unit (battery module or capacitor) to achieve three basic states: forward connection (switch closed in the forward conduction direction), reverse connection (switch closed in the reverse conduction direction), and complete disconnection from the load bus. This design theoretically allows each combined functional unit (containing one battery module switching assembly and one capacitor switching assembly) to combine into up to nine (3*3) different operating states. This high degree of freedom in state control enables the system to select the most suitable connection method (forward, reverse, or disconnection) for each battery module and capacitor based on real-time load demand, energy flow direction (power supply or absorption), and optimization objectives (such as precise voltage matching, surge suppression, and efficiency optimization). This significantly improves the overall control flexibility, dynamic response capability, and operating efficiency of the system, and provides the basic hardware support for implementing more complex energy management strategies.

[0030] Furthermore, the switch is an IGBT electronic switch.

[0031] Electronic switches operate at extremely high speeds (microseconds or even nanoseconds). The switching state is controlled by a voltage signal applied to the control terminal (such as the gate of an IGBT), which is a purely electronic process with almost no mechanical delay. Consequently, in practice, the current can be accurately controlled by adjusting the number of battery modules connected to the load bus.

[0032] In practical applications of using capacitors to suppress inrush current, the magnitude and dynamic decay curve (reduction curve) of the inrush current vary significantly due to different charging devices or load characteristics. Using capacitors with fixed capacitance values ​​or simply adjusting the number of capacitors connected makes it difficult to accurately match these diverse surge characteristics. A single capacitance value or simple increase or decrease in the number of capacitors cannot flexibly generate the required voltage / current dynamic response characteristics that match a specific inrush current reduction curve, resulting in poor surge suppression (overshoot or underresponse) or the need to connect too many unnecessary large-capacity capacitors, increasing system cost and size.

[0033] Furthermore, all capacitors have at least three capacitance levels to create different voltage reduction curves.

[0034] This application significantly expands the available capacitor combination schemes by designing all capacitors in the system to have at least three different capacitance levels (e.g., small, medium, and large). The connection of different capacitance levels (alone or in combination) produces voltage reduction curves with different time constants (RC) and decay rates. This design allows the system to flexibly select and combine capacitors of different capacitance levels connected to the load bus based on detected or anticipated surge current characteristics (e.g., peak size, duration, and decay slope).

[0035] Traditional battery power allocation methods struggle to simultaneously address the following: precisely meeting the power demands of transient charging loads, effectively matching the surge current reduction curve of specific charging equipment for optimal suppression, and ensuring balanced power output among the numerous connected battery modules (avoiding overcharging / over-discharging of individual modules) to extend the overall battery system's lifespan. Manual configuration or simple heuristic rules cannot achieve a globally optimal solution for these interconnected and sometimes conflicting objectives in dynamic scenarios.

[0036] Furthermore, the control device includes:

[0037] The external information acquisition module is used to acquire the current charging demand information in the charging station, including charging amount and charging current.

[0038] The charging plan generation module generates a charging plan based on charging demand information. The charging plan includes the required battery modules.

[0039] The charging port is connected to a power information acquisition module, which is used to obtain the model of the charging equipment connected to the charging station and generate the surge current variation curve of the charging equipment based on the charging equipment model.

[0040] The charging plan control module selects the required battery modules and capacitors to be connected to the load bus based on the particle swarm algorithm to meet the charging load.

[0041] Among them, the charging plan control module uses the power output balance coefficient of each battery module as the optimization target;

[0042] The charging plan control module uses the matching purpose with the surge current as the optimization objective.

[0043] This application employs a particle swarm optimization (PSO) algorithm in the charging plan control module of the control device to intelligently optimize the combination of battery modules and capacitors. The optimization goal of this algorithm is to minimize the output differences (such as current, power, or SOC change rate) between each connected battery module, ensuring that the aging rate of all participating battery modules is approximately consistent, thereby significantly extending the overall cycle life of the DC stacked energy storage battery and avoiding system performance constraints due to premature aging of individual modules.

[0044] Simultaneously, the actual current reduction curve generated after the selected capacitor combination is optimized to achieve the best match with the target surge current variation curve predicted based on the charging device model (e.g., minimizing error integral), thereby achieving effective and precise suppression of surge current peaks and avoiding excessively high or insufficient current decay rates due to improper capacitor selection. This solution can respond in real time to changes in charging demand and the connection of different charging devices. While meeting power requirements, it simultaneously optimizes battery life (balance) and system safety / stability (surge suppression effect), ensuring continuous and stable power supply, maximizing battery system lifespan, and effectively protecting the system from surge current impacts.

[0045] Furthermore, the power output balance coefficient is RT;

[0046]

[0047] Where N represents the total number of battery modules, n represents the index of the battery module, and D n This represents the number of cycles for the nth battery module. This represents the average number of cycles for all battery modules.

[0048] In the technical solution provided in this application, the power output equalization coefficient describes the sum of the squares of the differences between the cycle counts of all battery modules. Thus, the smaller the power output equalization coefficient, the closer the cycle counts of the battery modules are, and the power output equalization coefficient accurately describes the distribution of the cycle counts of the battery modules.

[0049] Furthermore, the matching coefficient is R;

[0050]

[0051] Where T represents the duration of the surge current, t represents the time index, k represents the capacitor index connected to the load bus, and K represents the total number of capacitors connected to the load bus. I represents the magnitude of the current output by the capacitor connected to the load bus at time t. t ′ represents the magnitude of the charging current at time t.

[0052] Existing particle swarm optimization algorithms typically construct fixed feasible solution matrices. These matrices cannot be updated in a timely manner, and particle diffusion within the feasible solution matrix is ​​affected by their movement trajectories. The fixed feasible set matrix prevents particles from accurately capturing the current update during iteration, resulting in low accuracy of the final selected feasible solutions. To address this issue, this application provides the following technical solution:

[0053] Furthermore, the feasible solution matrix ER constructed by the charging plan control module is dynamically updated;

[0054] EER = (E1; E2);

[0055] E1 is a sequence of battery modules, arranged from low to high based on the number of cycles of the battery modules;

[0056] E2 is a sequence of capacitor modules composed of capacitors, arranged from low to high based on the capacitance of the capacitors.

[0057] In the technical solution provided in this application, the feasible solution matrix ER will continuously update the arrangement order of each battery module in the first battery module sequence, the second battery module sequence, and the third battery module sequence according to the number of iterations. In this way, when a new battery module is selected each time, in order to achieve the optimal power output balance coefficient, the distance and position that the particles need to diffuse will be smaller, and it will be easier to find the best position in a smaller number of iterations.

[0058] Furthermore, the fitness function Fitness(X) constructed by the charging plan control module i )for:

[0059]

[0060] Among them, X i This represents the selection matrix for battery modules and capacitors in the i-th iteration, where K represents the total number of capacitors connected to the load bus, and k represents the index of the capacitor connected to the load bus. k Let I represent the output current of the k-th capacitor connected to the load bus, Q represent the total number of battery modules connected to the load bus, q represent the index of the battery module connected to the load bus, and I represent the output current of the k-th capacitor connected to the load bus. q RT represents the output current of the kth battery module connected to the load bus, RE represents the matching coefficient, and α1, α2, and α3 represent the first weighting coefficient, the second weighting coefficient, and the third weighting coefficient, respectively.

[0061] The beneficial effects of this application are as follows:

[0062] Rapid response and dynamic adjustment: When the capacitor is connected to the load bus in the forward direction, it quickly provides current to the load bus; when connected in the reverse direction, it quickly absorbs the current from the load bus.

[0063] Surge current suppression mechanism: In the initial stage of the system responding to load demand and connecting the required number of battery modules and capacitors to the load bus, the capacitors, due to their fast response characteristics, are the first to provide or absorb the main current. As time goes on, the terminal voltage of the capacitors connected to the load bus will change significantly due to discharge or charging (the voltage drops sharply when connected in the forward direction and rises when connected in the reverse direction), causing the current they contribute to decrease rapidly.

[0064] Smooth current transition: The rapid decay process of the capacitor current described above can effectively offset the surge current peak that may be generated when the charging port is first connected to the load bus in practice.

[0065] Stable and continuous power supply: Simultaneously, the control device gradually replaces the capacitors connected to the load bus with corresponding battery modules based on changes in the (charging / load) current. The battery modules provide stable and continuous voltage and current, thereby ensuring that the load bus ultimately receives a stable and continuous current supply, improving system stability. Attached Figure Description

[0066] Figure 1 This is a schematic diagram of a power load distribution system based on DC superimposed storage.

[0067] Figure 2 This is a schematic diagram of the switching device.

[0068] Figure 3 This is a schematic diagram of the switch assembly.

[0069] Figure 4 A circuit diagram showing the connections of the battery module, capacitors, and load bus.

[0070] Figure Labels

[0071] 1. Capacitor; 2. Battery module; 3. Load bus; 4. Switch. Detailed Implementation

[0072] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments. The same reference numerals in the accompanying drawings represent the same components. It should be noted that the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0073] Compared to the embodiments shown in the accompanying drawings, feasible embodiments within the scope of this application may have fewer components, include other components not shown in the drawings, different components, differently arranged components, or components with different connections, etc. Furthermore, two or more components shown in the drawings may be implemented in a single component, or a single component shown in the drawings may be implemented as multiple separate components.

[0074] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application pertains. The terms “first,” “second,” and similar terms used in this specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not necessarily indicate a quantity limitation. Terms such as “upper” and “lower” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0075] Example 1:

[0076] refer to Figure 1 The first embodiment of this application discloses a power load distribution system based on DC cascaded energy storage, including a DC cascaded energy storage battery, a switching device, and a control device.

[0077] The DC-side energy storage battery comprises several battery modules. Specifically, each battery module includes a set of series- or parallel connected cell units (e.g., lithium iron phosphate cells) and a battery management unit (BMU) integrated within the module. The BMU monitors the module's voltage, temperature, and operating status. Each battery module can independently output current (discharge) or independently absorb current (charge). Each battery module serves as the lowest controllable unit in this application.

[0078] Multiple switching devices are provided, and each battery module is connected to the load bus via its corresponding switching device. That is, each battery module is equipped with an independent switching device. This switching device controls whether its corresponding battery module is connected to the load bus. When the load bus requires a large current, a corresponding number of switching devices are closed, allowing more battery modules to connect to the load bus to provide a larger current. When the load bus requires a small current, a corresponding number of switching devices are opened, reducing the number of battery modules connected to the load bus.

[0079] The control device is used to acquire the power demand of the external power load and control the closing and opening of the corresponding switching device according to the power demand of the power load, so that the required number of battery modules can be connected to the load bus to meet the load demand.

[0080] The power demand of the electrical load refers to the output load power that the DC-side energy storage battery system needs to handle during the operation of the charging station. This demand is related to the management strategy of the charging station. The power demand of the electrical load must be within the power range that the DC-side energy storage battery system can handle. The method for obtaining the power demand of the electrical load will not be described in detail in this embodiment.

[0081] Specifically, the switching device includes two independent switching components and a capacitor. One switching component controls the direction in which the battery module is connected to the load bus. The other switching component controls the direction in which the capacitor is connected to the load bus.

[0082] When both the battery module and the capacitor are connected to the load bus in the forward direction, both the battery module and the capacitor provide a forward load to the load bus.

[0083] When both the battery module and the capacitor are connected to the load bus in reverse, both the battery module and the capacitor are used to absorb the load of the load bus.

[0084] When the battery module is connected to the load bus in the forward direction and the capacitor is connected to the load bus in the reverse direction, the battery module provides a positive load to the load bus, and the capacitor is used to absorb the load of the load bus.

[0085] When the battery module is connected to the load bus in reverse and the capacitor is connected to the load bus in forward, the battery module absorbs the load of the load bus, and the capacitor provides the forward load to the load bus.

[0086] The control device is configured to: respond to power load demand, control the switching device to connect at least one capacitor to the load bus and at least one battery module to the load bus, and gradually control the switching device according to changes in charging current to replace the capacitor connected to the load bus with the battery module.

[0087] For example, a power load requires a 30A charging current from a DC-DC tandem energy storage battery, but each battery module can only provide 0.3A. Therefore, 50 battery modules and 50 capacitors can be connected to the load bus. The 50 battery modules provide 15A of current, and the 50 capacitors also provide 15A, for a total of 30A of current applied to the load bus.

[0088] When the charging gun is connected to the load bus, a 30A current flows into it. This causes a surge current, which increases instantaneously. Since the capacitors have limited stored energy, this energy is consumed simultaneously with the sudden current increase, drastically reducing the current flowing into the charging gun. This counteracts the surge current and ensures current stability. Once the current stabilizes, the control device gradually replaces the depleted capacitors with other battery modules, ensuring stable power supply. Alternatively, appropriately empty capacitors can be connected in parallel to absorb the load on the load bus, further reducing the surge current.

[0089] The most critical part of the entire process is selecting a suitable battery module to connect to the load bus. To this end, this application provides the following technical solution:

[0090] like Figure 2 As shown: Each capacitor corresponds to only one battery module to form a combined functional unit. That is, each capacitor and battery module form a combination. The number of capacitors corresponds to the number of battery modules. This design allows for edge capacitor charging, as the capacitors can be directly charged through the battery modules, avoiding high current surges on the load bus. Furthermore, the overall combination of capacitors and battery modules can output diverse loads, increasing the precision of load adjustment.

[0091] Specifically, the positive terminal of the capacitor is connected to the load bus via a set of switches, and the negative terminal of the capacitor is connected to the load bus via a set of switches; the positive terminal of the battery module is connected to the load bus via a set of switches, and the negative terminal of the battery module is connected to the load bus via a set of switches.

[0092] The switch group includes at least two switches, one of which has its output connected to the positive terminal of the load bus, and the other has its output connected to the negative terminal of the load bus.

[0093] like Figure 3 and Figure 4 As shown, the switching assembly includes two switch groups, each of which includes two switches. One switching device includes eight switches. These eight switch groups can achieve nine states.

[0094] State 1: Battery module is connected to the load bus in the forward direction; capacitor is connected to the load bus in the forward direction; (the output voltage of the combined function unit is V1+V2), where V1 represents the output voltage of the battery module and V2 represents the output voltage of the capacitor.

[0095] State 2: Battery module connected to load bus in the forward direction; capacitor connected to load bus in the reverse direction; output voltage of the combined function unit is V1-V2.

[0096] State 3: Battery module is connected to the load bus in the forward direction; capacitor is not connected to the load bus; the output voltage of the combined function unit is V1.

[0097] State 4: Battery module connected to load bus in reverse; capacitor connected to load bus in forward; output voltage of combined function unit is -V1+V2.

[0098] State 5: Battery module connected to load bus in reverse; capacitor connected to load bus in reverse; output voltage of the combined function unit is -(V1+V2).

[0099] Status 6: Battery module is connected to the load bus in reverse; capacitor is not connected to the load bus; the output voltage of the combination function unit is -V1.

[0100] Status 7: Battery module not connected to load bus; capacitor connected to load bus in the forward direction; combined function unit output voltage is V2.

[0101] Status 8: Battery module not connected to load bus; capacitor connected to load bus in reverse; combined function unit output voltage is -V2.

[0102] Status 9: The battery module is not connected to the load bus; the capacitor is not connected to the load bus, and the output voltage of the combined function unit is 0.

[0103] The switch is an IGBT electronic switch, which has a high response rate and is not prone to mechanical wear during the closing process. When current passes through the switch, the current will not change due to wear of the contact parts.

[0104] Example 1 illustrates the hardware relationships of a power load distribution system based on DC-DC cascaded energy storage. This hardware system utilizes capacitors to handle changes in inrush current at the charging port. Specifically, when the DC-DC cascaded energy storage battery needs to supply current to the load bus, the current drops sharply when the capacitor releases current, reducing the impact of inrush current on the charging equipment. When the DC-DC cascaded energy storage battery is charging, the capacitor can share the instantaneous current connected to the battery module, reducing the magnitude of the current surge to the battery module and extending its lifespan.

[0105] Example 2:

[0106] When the battery module is charging, only the capacitor needs to have an energy storage function. Simply discharge the capacitor completely before charging, and then select state 5. In this state, both the battery module and the capacitor are charging simultaneously, and the capacitor can absorb most of the inrush current generated by the battery module.

[0107] When the charging gun is connected to the load bus, the surge current is very large, requiring more capacitors for compensation. Based on this, this application provides Embodiment 2:

[0108] Example 2 provides a specific implementation method for controlling the connection of capacitors and battery modules to the load based on Example 1. Specifically: all capacitors have at least three capacitance levels to form different voltage reduction curves. The voltage of the capacitors is less than the output voltage of the battery module, and the output voltage of the battery module minus the voltage of the capacitors equals 1.

[0109] The above describes the capacitor setup. The capacitor size is set according to requirements. The reason for setting three levels is to increase the adaptability of capacitor combinations. The number of capacitors in each level increases sequentially; the smaller the capacitor's capacitance, the more combinations can be formed, leading to more selections in practice and thus requiring more lower-level capacitors.

[0110] The control device includes: an external information acquisition module, a charging plan generation module, a charging port access power information acquisition module, and a charging plan control module.

[0111] The external information acquisition module acquires current charging demand information within the charging station, including charging quantity and charging current. The charging plan generation module generates a charging plan based on this demand information, including the required number of battery modules. Charging quantity refers to the total amount of electrical energy required, and charging current refers to the current required to be connected to the load bus. Therefore, based on the charging quantity and charging current, the charging plan generation module can calculate the required number of battery modules.

[0112] The charging port is connected to a power information acquisition module, which obtains the model of the charging equipment connected to the charging station and generates a surge current variation curve for that charging equipment based on the model. The surge current is related to the load connected to the charging bus; different loads generate different surge currents. Thus, based on the charging equipment model, such as vehicle brand or battery pack model, a pre-tested surge current variation curve can be obtained.

[0113] The charging plan control module selects the required battery modules and capacitors to be connected to the load bus based on the particle swarm optimization algorithm to meet the charging load. The charging plan control module uses the power output balancing coefficient of each battery module as the optimization target and the matching coefficient with the surge current as the optimization target.

[0114] The charging plan control module generates a load matching plan based on the following steps:

[0115] Step 1: Obtain the required number of battery modules A and the surge current variation curve;

[0116] Step 2: Construct the feasible solution matrix ER and update the feasible solution matrix ER;

[0117] ER = (E1; E2);

[0118] E1 is a sequence of battery modules, arranged from low to high based on the number of cycles of the battery modules;

[0119] E2 is a sequence of capacitor modules composed of capacitors, arranged from low to high based on the capacitance of the capacitors.

[0120] Step 3: Set the particle matrix;

[0121]

[0122] Where i represents the index of the particle, X i Let x represent the particle matrix consisting of the i-th particle. ily represents the position of the first battery module selected by the i-th particle in the feasible solution matrix ER. il Let represent the position of the first capacitor selected by the i-th particle in the feasible solution matrix ER, K represent the total number of capacitors connected to the load bus, and Q represent the total number of battery modules connected to the load bus.

[0123] Step 4: Initialize the population size, set U particles, and calculate the fitness function (Fitness(X)). i Update particle positions;

[0124]

[0125] X i Let I represent the particle matrix formed by the i-th particle, K represent the total number of capacitors connected to the load bus, and k represent the capacitor index connected to the load bus. k Let I represent the output current of the k-th capacitor connected to the load bus, Q represent the total number of battery modules connected to the load bus, q represent the index of the battery module connected to the load bus, and I represent the output current of the k-th capacitor connected to the load bus. q RT represents the output current of the kth battery module connected to the load bus, RE represents the matching coefficient, and α1, α2, α3 represent the first weighting coefficient, the second weighting coefficient, and the third weighting coefficient, respectively.

[0126]

[0127] Where N represents the total number of battery modules, n represents the index of the battery module, and D n This represents the number of cycles for the nth battery module. This represents the average number of cycles across all battery modules;

[0128]

[0129] Where T represents the duration of the surge current, t represents the time index, k represents the capacitor index connected to the load bus, and K represents the total number of capacitors connected to the load bus. I represents the magnitude of the current output by the capacitor connected to the load bus at time t. t ′ represents the magnitude of the charging current at time t;

[0130] Step 5: Stop updating when the number of updates reaches the maximum value or the fitness function reaches the preset threshold;

[0131] The particle position is updated as follows;

[0132]

[0133] in, This represents the new velocity matrix of particle i in the (g+1)th iteration. Let represent the current velocity component of particle i in the feasible solution matrix ER. Let w represent the particle matrix of particle i at the g-th iteration. j Let z represent the inertial parameters of the battery module, z represent the inertial parameters of the capacitor module, c1 and c2 are learning factors, and r1 and r2 are random matrices. G is the best particle matrix found so far for particle i. best This represents the optimal particle matrix for all particles in this iteration;

[0134]

[0135] in, Let represent the best, second-best, and third-best particle matrices among all particles at the i-th iteration, respectively.

[0136] w j =|(x ij -a)|, where a is a preset standard number, and a is greater than 1; x ij The position of the j-th battery module selected for the i-th particle in the feasible solution matrix ER;

[0137] In this application, w j =|(x ij -a)|, so that when the index of the j-th battery module selected by the i-th particle in the feasible solution matrix ER is small, w j The data is large, corresponding It will increase in size and guide the particles forward. Conversely, it will guide the particles backward. Thus, the inertial parameters of the battery module provided in this application conform to the design rules of the battery module matrix, and the model is easier to converge.

[0138] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A direct current (DC) storage-based power load distribution system, comprising: include: DC stacked energy storage battery, comprising several battery modules; Multiple switching devices are provided, and each battery module is connected to the load bus through a corresponding switching device. The control device acquires the power load demand and controls the corresponding switching device to close according to the power load demand so that the required number of battery modules can be connected to the load bus. The switching device includes: Two paired switch assemblies, one of which is connected to the battery module, and the other is connected to a capacitor. Control switch assembly to enable battery modules or capacitors to be connected to the load bus in either a forward or reverse manner; When both the battery module and the capacitor are connected to the load bus in the forward direction, both the battery module and the capacitor provide a forward load to the load bus. When both the battery module and the capacitor are connected to the load bus in reverse, both the battery module and the capacitor are used to absorb the load of the load bus. When the battery module is connected to the load bus in the forward direction and the capacitor is connected to the load bus in the reverse direction, the battery module provides a positive load to the load bus, and the capacitor is used to absorb the load of the load bus. When the battery module is connected to the load bus in reverse and the capacitor is connected to the load bus in forward, the battery module is used to absorb the load of the load bus, and the capacitor provides the forward load to the load bus. The control device is configured to: respond to power load demand, control the switching device to connect at least one capacitor to the load bus and at least one battery module to the load bus, and gradually control the switching device to replace the capacitor connected to the load bus with the battery module according to the change of charging current.

2. The DC-accumulation-based power load distribution system according to claim 1, wherein Each capacitor corresponds to only one battery module to form a combined functional unit; The positive terminal of the capacitor is connected to the load bus through a set of switches, and the negative terminal of the capacitor is connected to the load bus through a set of switches. The positive terminal of the battery module is connected to the load bus via a set of switches, and the negative terminal of the battery module is connected to the load bus via a set of switches.

3. The power load distribution system based on DC superimposed storage according to claim 1, characterized in that, The switch group includes at least two switches, one of which has its output connected to the positive terminal of the load bus, and the other has its output connected to the negative terminal of the load bus.

4. The power load distribution system based on DC superimposed storage according to claim 3, characterized in that, The switch is an IGBT electronic switch.

5. The power load distribution system based on DC superimposed storage according to any one of claims 1 to 4, characterized in that, All capacitors should have at least three capacitance levels to create different voltage reduction curves.

6. The power load distribution system based on DC superimposed storage according to claim 5, characterized in that, The control device includes: The external information acquisition module is used to acquire the current charging demand information in the charging station, including charging amount and charging current. The charging plan generation module generates a charging plan based on charging demand information. The charging plan includes the required battery modules. The charging port is connected to a power information acquisition module, which is used to obtain the model of the charging equipment connected to the charging station and generate the surge current variation curve of the charging equipment based on the charging equipment model. The charging plan control module selects the required battery modules and capacitors to be connected to the load bus based on the particle swarm algorithm to meet the charging load. Among them, the charging plan control module uses the power output balance coefficient of each battery module as the optimization target; The charging plan control module uses the matching coefficient with the surge current as the optimization target.

7. The power load distribution system based on DC superimposed storage according to claim 6, characterized in that, The power output balance factor is RT; RT ; Where N represents the total number of battery modules, n represents the index of the battery module, and D n This represents the number of cycles for the nth battery module. This represents the average number of cycles for all battery modules.

8. The power load distribution system based on DC superimposed storage according to claim 7, characterized in that, The matching coefficient is RE; ； Where T represents the duration of the surge current, t represents the time index, k represents the capacitor index connected to the load bus, and K represents the total number of capacitors connected to the load bus. This represents the magnitude of the current output by the k-th capacitor connected to the load bus at time t. This indicates the magnitude of the charging current at time t.

9. The power load distribution system based on DC superimposed storage according to claim 8, characterized in that, The feasible solution matrix ER constructed by the charging plan control module is dynamically updated; ； E1 is a sequence of battery modules, arranged from low to high based on the number of cycles of the battery modules; E2 is a sequence of capacitor modules composed of capacitors, arranged from low to high based on the capacitance of the capacitors.

10. The power load distribution system based on DC superimposed storage according to claim 9, characterized in that, Fitness function constructed by the charging plan control module for: ； Among them, X i Let K represent the selection matrix for battery modules and capacitors in the i-th iteration, where K represents the total number of capacitors connected to the load bus, and k represents the index of the capacitor connected to the load bus. Let Q represent the output current of the k-th capacitor connected to the load bus, Q represent the total number of battery modules connected to the load bus, and q represent the index of the battery module connected to the load bus. RT represents the output current of the kth battery module connected to the load bus, RE represents the matching coefficient, and α1, α2, and α3 represent the first weighting coefficient, the second weighting coefficient, and the third weighting coefficient, respectively.

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