Super-wide voltage flash charging pile control method based on multi-level topology reconstruction

Abstract

This application discloses a control method for ultra-wide voltage flash charging piles based on multi-level topology reconstruction. The method includes: building a hardware system for an ultra-wide voltage flash charging pile based on multi-level topology reconstruction; detecting anomalies through initial system parameters; determining the corresponding operating mode of the hardware system according to vehicle charging demand parameters; performing closed-loop feedback control based on the operating mode, adjusting the modulation ratio of the active front end on the grid side to stabilize the DC bus voltage, configuring the switching state of the intermediate topology reconstruction stage to reconstruct the connection mode of the DC bus capacitor, and adjusting the phase shift angle and operating frequency of the subsequent dual-channel high-frequency isolated DC-DC converter stage to match the vehicle charging demand parameters. Through multi-mode topology reconstruction, differentiated circuit structures are matched under different voltage and power demands, achieving excellent loss control under all operating conditions and improving the system's energy conversion efficiency.

Description

Technical Field

[0001] This application relates to the field of charging pile control, specifically to a control method for ultra-wide voltage flash charging piles based on multi-level topology reconstruction. Background Technology

[0002] With the increasing penetration rate of electric vehicles and the upgrading of energy replenishment needs, ultra-wide voltage adaptation and high-power flash charging have become the core development directions of charging pile technology. In traditional solutions, flash charging piles mostly adopt a two-stage architecture of "active front-end + fixed topology DC-DC (Direct Current to Direct Current)". Among them, multi-level converters have become the mainstream choice for the front-end active front-end due to their low voltage stress and excellent harmonic characteristics. The back-end often adopts a high-frequency isolated DC-DC topology with multiple modules in parallel or input series output series (ISOS) to improve power capacity. However, this type of topology still faces key problems in actual operation, such as poor adaptability to multiple operating conditions, high losses, and insufficient coordinated control. Summary of the Invention

[0003] To address the aforementioned issues, this application proposes a control method for ultra-wide voltage flash charging piles based on multi-level topology reconstruction, including: A hardware system for an ultra-wide voltage flash charging pile based on multi-level topology reconstruction is constructed. The hardware system includes: an active front-end on the grid side, an intermediate topology reconstruction stage, a dual-channel high-frequency isolated DC-DC converter stage, a control unit, a detection module, and a communication module. The detection module collects the system initial parameters corresponding to the hardware system and performs anomaly detection based on the system initial parameters. The control unit collects the vehicle charging demand parameters corresponding to the electric vehicle through the communication module, and determines the operating mode corresponding to the hardware system based on the vehicle charging demand parameters. Closed-loop feedback control is performed based on the operating mode to adjust the modulation ratio of the active front end on the grid side to stabilize the DC bus voltage, configure the switching state of the intermediate topology reconfiguration stage to reconfigure the connection mode of the DC bus capacitor, and adjust the phase shift angle and operating frequency of the subsequent dual-channel high-frequency isolated DC-DC converter stage to match the vehicle charging demand parameters.

[0004] In one example, the active front end on the grid side includes AC input terminals for phases A, B, and C, and a first switch and a second switch corresponding to each phase; the input terminal of the first switch is connected to the positive terminal of the DC bus, and the output terminal is connected to the AC input of each phase; the input terminal of the second switch is connected to the AC input of each phase, and the output terminal is connected to the negative terminal of the DC bus. The intermediate topology reconfiguration stage includes corresponding third switches, first DC bus capacitors, and second DC bus capacitors; the first DC bus capacitor and the second DC bus capacitor are connected in series, with the upper end of the first DC bus capacitor connected to the positive terminal of the DC bus and the lower end of the second DC bus capacitor connected to the negative terminal of the DC bus; the third switch is a bidirectional switch, connecting each phase AC input to the midpoint of the DC bus; The subsequent dual-channel high-frequency isolated DC-DC converter stage includes two symmetrical parallel branches, each containing a bidirectional full-bridge isolated DC-DC converter and an output filter capacitor. The input terminal of the bidirectional full-bridge isolated DC-DC converter in the first branch corresponding to the first DC bus capacitor is connected to the positive terminal of the DC bus and the midpoint of the DC bus. The input terminal of the bidirectional full-bridge isolated DC-DC converter in the second branch corresponding to the second DC bus capacitor is connected to the negative terminal of the DC bus and the midpoint of the DC bus. The output terminal of the bidirectional full-bridge isolated DC-DC converter in each branch is connected in parallel with its corresponding output filter capacitor.

[0005] In one example, the control unit collects vehicle charging demand parameters corresponding to the electric vehicle through the communication module, and determines the operating mode corresponding to the hardware system based on the vehicle charging demand parameters, specifically including: The control unit collects the vehicle charging demand parameters corresponding to the electric vehicle through the communication module. The vehicle charging demand parameters include charging voltage demand and charging current demand, and the charging power is obtained based on the charging voltage demand and the charging current demand. Based on the vehicle charging demand parameters, a preset threshold is compared to determine the corresponding operating mode of the hardware system; If the charging voltage requirement is lower than a preset voltage threshold and the charging power is lower than a preset power threshold, then the operating mode of the hardware system is determined to be a low-voltage, low-power mode. If the charging voltage requirement is lower than a preset voltage threshold and the charging power is higher than a preset power threshold, then the operating mode of the hardware system is determined to be low voltage high power mode. If the charging voltage requirement is higher than the preset voltage threshold, then the operating mode of the hardware system is determined to be the high-voltage, high-power mode.

[0006] In one example, closed-loop feedback control based on the operating mode specifically includes: The operating mode is determined to be the low-voltage, low-power mode; For the intermediate topology reconfiguration stage, the third switch is normally turned on, the second switch is normally turned off, the first DC bus capacitor is connected to the circuit separately, and the second DC bus capacitor is made to float. For the active front end on the grid side, unity power factor control is initiated, the DC bus voltage is determined according to the charging voltage requirement, and the voltage of the first DC bus capacitor is maintained stable through pulse width modulation. For the subsequent dual-channel high-frequency isolated DC-DC converter stage, the first branch is connected separately, the switching frequency is reduced, and the light-load resonant mode is started. The charging voltage and charging current requirements are achieved through phase shift control.

[0007] In one example, closed-loop feedback control based on the operating mode specifically includes: The operating mode is determined to be the low-voltage high-power mode; For the intermediate topology reconfiguration stage, the second switch is kept normally on, so that the first DC bus capacitor and the second DC bus capacitor are connected in parallel to the circuit; For the active front end on the grid side, constant voltage current limiting control is initiated. The voltage of the first DC bus capacitor and the second DC bus capacitor are detected through the capacitor voltage equalization loop. The voltage of the first DC bus capacitor and the second DC bus capacitor are made consistent by dynamically adjusting the rectified current distribution. For the aforementioned dual-channel high-frequency isolated DC-DC converter stage, the first branch and the second branch are connected. Through the current sharing control strategy, the output current of the first branch and the second branch is detected. By fine-tuning the DC-DC phase shift angle, the deviation of the output current of the first branch and the second branch is made lower than a preset ratio, and the first branch and the second branch are made to work together to operate at full load.

[0008] In one example, closed-loop feedback control based on the operating mode specifically includes: The operating mode is determined to be a high-voltage, high-power mode; For the intermediate topology reconfiguration stage, the second switch is kept normally on, so that the first DC bus capacitor and the second DC bus capacitor are connected in series in the circuit; For the active front end on the grid side, the output voltage is increased to keep the voltages of the first DC bus capacitor and the second DC bus capacitor consistent, and the average current at the midpoint of the DC bus is brought close to 0 by adjusting the pulse width modulation rectification timing. For the subsequent dual-channel high-frequency isolated DC-DC converter stage, the first branch and the second branch are connected, and the bidirectional full-bridge isolated DC-DC converter is made to operate at full power. The high-frequency transformer rectification timing in the bidirectional full-bridge isolated DC-DC converter is finely adjusted according to the charging voltage requirement through a constant power control strategy.

[0009] In one example, closed-loop feedback control based on the operating mode specifically includes: For the low-voltage, low-power mode, the detection module collects the voltage, charging voltage requirement, and charging current requirement of the first DC bus capacitor and feeds them back to the control unit. If any parameter deviates from the target value by more than a preset amount, the modulation ratio and DC-DC phase shift angle of the active front end are finely adjusted to perform closed-loop regulation. For the low-voltage high-power mode, the detection module collects the DC bus current and charging power and feeds them back to the control unit. If there is an overload of the charging power or the voltage deviation between the first DC bus capacitor and the second DC bus capacitor exceeds a first preset deviation value, the current limiting protection and alarm mechanism is activated, and the charging power is finely adjusted. For the high-voltage, high-power mode, the detection module collects grid-side harmonics, DC bus voltage fluctuations, and device operating status, and feeds them back to the control unit for dynamic correction.

[0010] In one example, the method further includes: The switching to the operating mode is determined, and the power difference is obtained based on the power requirements of the target mode and the power requirements of the current mode. Adjust the output current of the active front end on the grid side according to the direction of the power difference; The mode switching action is performed, and during the execution, the first voltage fluctuation is determined by the voltage feedback compensation coefficient, and the first voltage fluctuation is suppressed by closed-loop regulation.

[0011] In one example, the method further includes: The main control unit collects the output power of each flash charging station and calculates the total load and average power. Determine the power deviation of each flash charging station; If there is a designated flash charging station with a power deviation higher than the second preset deviation value, an instruction is issued to adjust the DC-DC phase shift angle of the designated flash charging station; Based on the obtained total harmonic distortion rate of the grid current, adjust the pulse width modulation rectification timing of each flash charging pile.

[0012] In one example, the method further includes: The second voltage fluctuation is determined based on the collected grid node voltages; If the second voltage fluctuation is higher than the preset fluctuation, the total charging power of the charging station is dynamically adjusted according to the direction of the voltage fluctuation.

[0013] The ultra-wide voltage flash charging pile control method based on multi-level topology reconstruction proposed in this application can bring the following benefits: Achieving excellent loss control across all operating conditions and improving system energy conversion efficiency: Through multi-modal topology reconstruction, differentiated circuit structures are matched to different voltage and power requirements: low-voltage, low-power modes activate only some circuit modules and reduce switching frequency, thereby reducing switching and conduction losses; low-voltage, high-power and high-voltage, high-power modes fully unleash the capacity potential of power devices through topology optimization using parallel / series capacitors. Compared to traditional fixed-topology flash charging stations, this reduces switching losses in low-voltage, low-power scenarios and improves system conversion efficiency across all operating conditions, effectively addressing the industry pain point of high multi-condition losses in traditional topologies.

[0014] Covering an ultra-wide voltage and power range, compatible with the charging needs of various types of electric vehicles: Three operating modes enable output voltage from 200V to 1000V and output power covering all scenarios from low-power energy replenishment to high-power fast charging. It can meet the fast charging and daily energy replenishment needs of 400V low-voltage platform vehicles, and also adapt to the high-power flash charging needs of 800V high-voltage platform vehicles. There is no need to configure dedicated charging piles for different models, which improves the versatility of charging equipment and site utilization, and solves the problem of narrow voltage and power compatibility of traditional charging piles.

[0015] Achieving smooth mode switching and improving the reliability of the charging system: A collaborative control strategy of power pre-compensation and capacitor pre-charge / discharge is introduced. By adjusting the output of the front-end AFE in advance, the power surge and bus voltage fluctuation during the mode switching process are suppressed, and the DC bus voltage fluctuation is controlled within the preset range of the rated voltage. This avoids current distortion and sudden voltage stress changes in devices during the switching process, extends the service life of power devices, and solves the defects of traditional mode switching technology, such as large impact and poor stability.

[0016] Achieving multi-pile parallel coordination and grid-side friendly interaction supports the large-scale deployment of charging stations: The power balancing control strategy can suppress the power deviation of a single pile during multi-pile parallel operation within a preset range. At the same time, through grid voltage fluctuation feedback control, the total load of the charging station is dynamically adjusted to control the voltage fluctuation of the grid nodes within a preset range, and the total harmonic distortion rate of the grid current is lower than the preset range, meeting the relevant standards for power quality. This avoids harmonic superposition and module overload problems when multiple piles are connected in parallel, and reduces the impact of high-power charging loads on the grid, providing technical support for the large-scale construction of charging stations. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart illustrating the ultra-wide voltage flash charging pile control method based on multi-level topology reconstruction in the embodiments of this application; Figure 2 This is a schematic diagram of a portion of the circuit structure in the hardware system under one scenario in an embodiment of this application; Figure 3 This is a schematic diagram of the process for determining the operating mode in one scenario of this application embodiment; Figure 4 This is a partial circuit structure diagram of a scenario in the low-voltage, low-power mode according to one embodiment of this application; Figure 5 This is a partial circuit structure diagram of a low-voltage, high-power mode under one scenario in the embodiments of this application; Figure 6 This is a partial circuit structure diagram of a high-voltage, high-power mode under one scenario in an embodiment of this application. Detailed Implementation

[0018] 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 and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] The technical solutions provided by the various embodiments of this application are described in detail below with reference to the accompanying drawings.

[0020] Traditional solutions often employ fixed-structure flash charging pile topologies, which dynamically adjust the circuit configuration based on the vehicle's voltage platform (e.g., 400V / 800V) and real-time power requirements. This typically results in a narrow voltage and power compatibility range and high losses under various operating conditions.

[0021] The total circuit loss of this flash charging station topology can be expressed as the superposition of switching loss and conduction loss, as shown in Formula 1: Formula 1; in, This represents the total circuit loss. For switching losses, For conduction loss, This is the switching loss factor. This is the DC bus voltage. For output current, For switching frequency, This is the on-resistance of the device.

[0022] In low-voltage, low-power power replenishment scenarios (such as output voltage) =400V, Output Power =30kW), the fixed high-voltage topology remains unchanged. =1200V operation leads to switching losses Follow It increases proportionally; however, in high-voltage, high-power scenarios (such as charging voltage requirements) =800V, Output Power =150kW), the insufficient voltage margin of the fixed topology will limit the release of power device capacity, and the energy conversion efficiency under all operating conditions is difficult to exceed 93%.

[0023] Traditional solutions often employ topologies with simple mode switching capabilities. During mode switching, the DC bus voltage fluctuation can be expressed as shown in Equation 2: Formula 2; in, This represents the first voltage fluctuation of the DC bus. This represents the power change before and after mode switching. The duration of the mode switching process. This is the equivalent capacitance of the DC bus.

[0024] However, this topology typically only focuses on the state switching of a single-stage circuit, lacking a full-link coordinated control strategy for the front-end active front-end, the intermediate topology reconfiguration stage, and the rear-end DC-DC converter, and lacking coordinated control for multi-mode switching.

[0025] Traditional solutions often employ a single-pile independent control mode. When multiple piles are connected in parallel, the power distribution deviation can be expressed as shown in Formula 3: Formula 3; in, Let i be the output power of the i-th pile. Where N is the total load and N is the number of parallel piles. The power allocation deviation of the i-th charging pile. Affected by differences in device parameters and communication latency. This can reach 5% to 8% of the rated power of a single pile, leading to uneven current distribution between modules and the superposition of harmonics. The total harmonic distortion (THD) on the grid side is shown in Formula 4: Formula 4; in, Let h be the total harmonic distortion of the current, and h be the harmonic order. The effective value of the h-th harmonic current. This is the effective value of the fundamental current.

[0026] When the total number of charging piles N operating in parallel is greater than or equal to 4, It is easy to exceed the standard limit of 5%; at the same time, it lacks a coordinated dispatch mechanism with the power grid, and the random access of high-power charging loads will cause voltage fluctuations at power grid nodes, as shown in Formula 5: Formula 5; in, This represents the voltage fluctuation at the grid nodes. The total charging load power of all parallel charging piles, The equivalent resistance of the line from the power source point on the grid to the charging pile access point. This is the voltage at the grid node. When... =600kW, The rate can reach 2% to 3%, which restricts the large-scale deployment of charging stations.

[0027] Traditional solutions typically optimize only a single problem, making it difficult to address multiple objectives simultaneously. For example, increasing the number of switches to improve voltage adaptability leads to a simultaneous increase in circuit complexity and power losses; or increasing power capacity through modular parallel connections lacks dynamic control over power balancing between modules. The cost function for multi-objective optimization can be expressed as shown in Equation Six: Formula Six; Where J is the cost function of the multi-objective optimization. This represents the total circuit loss. This represents the first voltage fluctuation of the DC bus. The total harmonic distortion of the current. , , These are the corresponding weighting coefficients.

[0028] Generally speaking, fixed weighting makes it difficult to adapt to ultra-wide voltage ranges. =200V~1000V), low-loss operation ( The overall performance and reliability of the flash charging pile system are limited by factors such as the ≤5% requirement, the need for multi-module collaboration and grid-friendly operation to achieve comprehensive advantages.

[0029] Based on this, such as Figure 1 As shown, this application provides a control method for ultra-wide voltage flash charging piles based on multi-level topology reconstruction, including: S101: Build a hardware system for an ultra-wide voltage flash charging pile based on multi-level topology reconstruction. The hardware system includes: an active front-end on the grid side, an intermediate topology reconstruction stage, a downstream dual-channel high-frequency isolated DC-DC converter stage, a control unit, a detection module, and a communication module.

[0030] A hardware system for an ultra-wide voltage flash charging station based on multi-level topology reconfiguration was built, including an active front end (AFE) on the grid side, an intermediate topology reconfiguration stage, a dual-channel high-frequency isolated DC-DC converter stage, a control unit, a detection module, and a communication module. The electrical connections and parameter settings of each module were completed to ensure the normal operation of the hardware.

[0031] The control unit is initialized, and the control parameters, feedback adjustment thresholds and protection parameters for each mode are set. The detection module and communication module are started, and the communication link between the control unit and the grid-side active front end, the downstream dual-channel high-frequency isolated DC-DC converter stage, the vehicle battery management system (BMS) and the charging station main control unit is established.

[0032] The active front-end on the grid side primarily rectifies the three-phase AC power from the grid into a stable DC bus voltage, achieving unity power factor, harmonic suppression, and grid-friendly interaction. The intermediate topology reconfiguration stage mainly changes the series / parallel connection of the DC bus capacitors through switching transistor combinations, enabling topology switching between three modes: low-voltage low-power, low-voltage high-power, and high-voltage high-power. The subsequent dual-channel high-frequency isolated DC-DC converter stage converts the DC bus voltage to the charging voltage / current required by the electric vehicle, supporting single-channel frequency reduction, dual-channel current sharing, or full-power operation, and providing electrical isolation. The control unit primarily determines the operating mode based on BMS requirements and detection feedback, generating switching transistor drive, AFE modulation, and DC-DC phase-shift control signals to execute end-to-end coordinated control. The detection module primarily collects real-time parameters such as grid voltage, DC bus capacitor voltage, output current / voltage, and power of each charging pile, providing data for closed-loop control and protection. The communication module primarily establishes communication with the onboard BMS, the charging station main control unit, and other charging piles, acquiring charging requirements and receiving power scheduling commands.

[0033] Specifically, such as Figure 2 As shown, the active front end on the grid side includes AC input terminals for phases A, B, and C, as well as a first switch and a second switch corresponding to each phase. The AC power supply for each phase is connected to the first switch and the second switch through a filter inductor (also called the input inductor).

[0034] The first switching transistor includes , , The second switching transistor includes , , These correspond to phases A, B, and C, respectively. The input terminal of the first switch is connected to the positive terminal of the DC bus, and the output terminal is connected to the AC input of each phase; the input terminal of the second switch is connected to the AC input of each phase, and the output terminal is connected to the negative terminal of the DC bus.

[0035] The intermediate topology reconfiguration stage includes the corresponding third switching transistors and the first DC bus capacitor. Second DC bus capacitor The first DC bus capacitor and the second DC bus capacitor are connected in series. The upper end of the first DC bus capacitor is connected to the positive terminal of the DC bus, and the lower end of the second DC bus capacitor is connected to the negative terminal of the DC bus. The first DC bus capacitor... Second DC bus capacitor In series, the common node of the two is the midpoint of the DC bus, together forming the main body of a three-level DC bus with a midpoint.

[0036] The third switching transistor includes , , These correspond to phases A, B, and C respectively. The third switch is a bidirectional switch, connecting the AC input of each phase to the midpoint of the DC bus.

[0037] The subsequent dual-channel high-frequency isolated DC-DC converter stage includes two symmetrical parallel branches, each containing a bidirectional full-bridge isolated DC-DC converter and an output filter capacitor. The input terminal of the bidirectional full-bridge isolated DC-DC converter in the first branch, corresponding to the first DC bus capacitor, is connected to the positive terminal of the DC bus and the midpoint of the DC bus. The input terminal of the bidirectional full-bridge isolated DC-DC converter in the second branch, corresponding to the second DC bus capacitor, is connected to the negative terminal of the DC bus and the midpoint of the DC bus. The output terminal of the bidirectional full-bridge isolated DC-DC converter in each branch is connected in parallel with its corresponding output filter capacitor.

[0038] like Figure 2 As shown, a single bidirectional full-bridge isolated DC-DC converter sequentially includes a primary-side H-bridge, an LLC resonant network, an isolation transformer, and a secondary-side H-bridge. The primary-side and secondary-side H-bridges are used to form a full-bridge (H-bridge). The primary-side H-bridge includes two upper switches (the input is connected to the positive terminal of the DC bus, and the output is connected to the midpoint of the DC bus) and two lower switches (the input is connected to the positive terminal of the DC bus, and the output is connected to the midpoint of the DC bus). The secondary-side H-bridge includes four switches, whose inputs are connected to the secondary winding of the transformer to rectify the high-frequency AC to DC, and whose outputs are connected to the secondary DC bus.

[0039] An inductor-inductor-capacitor (LLC) resonant network consists of one resonant inductor (with a corresponding terminal) and one resonant capacitor, connected in series between the midpoints of the two arms of the primary-side H-bridge and connected to the primary side of the isolation transformer to achieve soft switching and resonant transformation.

[0040] The primary winding of the isolation transformer is connected to a resonant network, and the secondary winding is connected to a secondary H-bridge to achieve electrical isolation and voltage transformation between the primary and secondary sides.

[0041] S102: The detection module collects the system initial parameters corresponding to the hardware system and performs anomaly detection using the system initial parameters.

[0042] The initial parameters of the system are mainly used to describe the initial state of the hardware system, and may include the mains input voltage. DC bus capacitor voltage , The control unit determines the initial state of the system based on the initial parameters of the system, ensuring that each device is in a standby ready state and there are no abnormal alarms. For example, the DC bus capacitor is pre-charged to the set voltage range, the drive signals of each switch are self-tested, and the PI regulator parameters and mode judgment thresholds in the control algorithm are initialized to prepare for subsequent operation.

[0043] S103: The control unit collects the vehicle charging demand parameters corresponding to the electric vehicle through the communication module, and determines the operating mode corresponding to the hardware system based on the vehicle charging demand parameters.

[0044] like Figure 3 As shown, vehicle charging demand parameters are mainly used to describe the specific needs of electric vehicles during the charging process. The control unit receives vehicle charging demand parameters fed back by the Battery Management System (BMS) through the communication module, which includes the charging voltage requirements of the electric vehicle. Charging current requirements The charging power is calculated in real time based on the charging voltage and charging current requirements. .

[0045] Based on the vehicle charging demand parameters, a comparison is made with preset thresholds to determine the corresponding operating mode of the hardware system. This is primarily based on the charging voltage requirement. With charging power With preset voltage threshold Preset power threshold By comparing the results, the operating mode of the system can be determined.

[0046] Output voltage threshold based on electric vehicle charging demand (Typical value 400V, suitable for low-voltage platform vehicles) and output power threshold (Typical value 30kW, distinguishing between low-power charging and high-power fast charging), the operating status of flash charging piles is divided into three modal regions, with the specific judgment conditions as follows: If the charging voltage requirement is lower than the preset voltage threshold ( And the charging power is lower than the preset power threshold ( If the operating mode of the hardware system is low voltage and low power, then the charging demand is low voltage and low power replenishment, and the topology adopts a DC bus capacitor. The structure is output separately. Suspension does not participate in energy transfer.

[0047] If the charging voltage requirement is lower than the preset voltage threshold ( And the charging power is higher than the preset power threshold ( If the operating mode of the hardware system is determined to be low-voltage, high-power mode, then the charging requirement is low-voltage, high-power fast charging, and the topology uses a DC bus capacitor. and The parallel output structure increases the bus current capacity.

[0048] If the charging voltage requirement is higher than the preset voltage threshold ( If this is the case, then the operating mode of the hardware system is determined to be high-voltage, high-power mode; at this time, the power demand is high-voltage, high-power, fast charging, and the topology adopts a DC bus capacitor. and The series output structure increases the bus output voltage.

[0049] S104: Perform closed-loop feedback control based on the operating mode, adjust the modulation ratio of the active front end on the grid side to stabilize the DC bus voltage, configure the switching state of the intermediate topology reconfiguration stage to reconfigure the connection mode of the DC bus capacitor, and adjust the phase shift angle and operating frequency of the subsequent dual-channel high-frequency isolated DC-DC converter stage to match the vehicle charging demand parameters.

[0050] Specifically, in Example 1, the operating mode is determined to be a low-voltage, low-power mode. This mode prioritizes minimizing losses and activates only a portion of the circuit modules. In this case, such as... Figure 4 As shown, for the intermediate topology reconfiguration stage, the third switch (including...) , , ) is normally conducting, turning on the second switch (including , , Normally turned off, causing the first DC bus capacitor to... A separate circuit is connected, and the second DC bus capacitor is... Suspended, its connection to the circuit is disconnected, preventing it from participating in energy transfer. At this time, the DC bus voltage... =Voltage of the first DC bus capacitor .

[0051] For the active front end on the grid side, initiate unity power factor control based on charging voltage requirements. The DC bus voltage can be determined as shown in Formula 7: Formula 7; in, This is the DC bus voltage. For charging voltage requirements, The boost factor is the DC-DC converter after the boost stage, with a value range of [1.1, 1.2], to avoid excessive switching losses caused by excessive bus voltage.

[0052] The voltage of the first DC bus capacitor is maintained by pulse width modulation (PWM). Stability.

[0053] For the subsequent dual-channel high-frequency isolated DC-DC converter stage, the first branch is connected separately, and the switching frequency is reduced (for example, reduced to 30%~50% of the rated frequency) to start the light-load resonant mode. The charging voltage requirement is achieved through phase-shift control. Charging current requirements The output is used to realize switching losses according to Formula 8. The reduction: Formula 8; in, This represents the total circuit loss. This is the switching loss factor. This is the DC bus voltage. For output current, For switching frequency, This is the on-resistance of the device.

[0054] For low-voltage, low-power modes, the voltage of the first DC bus capacitor is acquired through a detection module. Charging voltage requirements Charging current requirements The data is fed back to the control unit; if any parameter deviates from the target value by more than the preset level, the modulation ratio and DC-DC phase shift angle of the active front end are finely adjusted for closed-loop regulation.

[0055] During modal operation, if the charging voltage requirement fed back by the BMS... Charging current requirements If a change occurs, return to re-evaluate the mode; otherwise, maintain the current mode.

[0056] In Example 2, the operating mode is determined to be a low-voltage, high-power mode. The core objectives of this mode are to increase current capacity and balance module losses. At this time, as follows... Figure 5 As shown, for the intermediate topology reconfiguration stage, all control switches are normally turned on and off (the second switch is turned off). , , (Normal conduction), causing the first DC bus capacitor to... Second DC bus capacitor Parallel connection to the circuit increases the bus current capacity; at this time, the DC bus voltage... = DC bus current .

[0057] For the active front end on the grid side, constant voltage and current limiting control is initiated, and the voltages of the first DC bus capacitor and the second DC bus capacitor are detected through the capacitor voltage balancing loop (respectively...). , By dynamically adjusting the rectified current distribution, the voltages of the first DC bus capacitor and the second DC bus capacitor are made consistent. = The voltage deviation of the first DC bus capacitor and the second DC bus capacitor is controlled within 5V. When the voltage deviation (through...) Calculated voltage deviation When the voltage is greater than 5V, the three-phase rectified current distribution is dynamically adjusted to make... It converges to within the threshold.

[0058] For the subsequent dual-channel high-frequency isolated DC-DC converter stage, the first and second branches are connected. A current-sharing control strategy is used to detect the output currents of the first and second branches (respectively...). , The deviation between the output currents of the first and second branches is corrected by finely adjusting the phase shift angle φ. Calculate the current deviation The first branch and the second branch are operated at full load in coordination, with the first branch being lower than the preset ratio (e.g., lower than 2%).

[0059] For low-voltage, high-power modes, the DC bus current is collected through a detection module. Charging power And feed back to the control unit; if there is a charging power overload or the first DC bus capacitor... With the second DC bus capacitor If the corresponding voltage deviation exceeds the first preset deviation value, the current limiting protection and alarm mechanism will be activated, and the charging power will be finely adjusted. .

[0060] During modal operation, if the charging voltage requirement fed back by the BMS... Charging current requirements If a change occurs, return to re-evaluate the mode; otherwise, maintain the current mode.

[0061] In Example 3, the operating mode is determined to be a high-voltage, high-power mode. The core objective of this mode is to increase the voltage level and unleash power potential. At this time, such as... Figure 6 As shown, for the intermediate topology reconfiguration stage, all control switches are normally turned on and off (the second switch is turned off). , , (Normal conduction) makes the first DC bus capacitor Second DC bus capacitor By connecting the circuit in series, the output DC bus voltage is increased. At this time, the DC bus voltage... + This meets the charging needs of high-voltage platform vehicles.

[0062] For the active front end on the grid side, the output voltage is increased to maintain the voltage of the first DC bus capacitor and the second DC bus capacitor being consistent, as shown in Formula Nine: Formula Nine; in, , These are the voltages of the first DC bus capacitor and the second DC bus capacitor, respectively. This is the DC bus voltage.

[0063] By adjusting the pulse width modulation rectification timing, the average current at the midpoint of the DC bus is brought close to 0, thus avoiding uneven voltage stress on the device caused by midpoint potential shift.

[0064] For the subsequent dual-channel high-frequency isolated DC-DC converter stage, the first and second branches are connected, and the bidirectional full-bridge isolated DC-DC converter is operated at full power. Through a constant power control strategy, the rectification timing of the high-frequency transformer in the bidirectional full-bridge isolated DC-DC converter is finely adjusted according to the charging voltage requirements to achieve high-voltage precise output.

[0065] For high-voltage, high-power modes, the detection module collects grid-side harmonics, DC bus voltage fluctuations, and device operating status, and feeds this data back to the control unit for dynamic correction, ensuring power quality and system stability. For example, when the total harmonic distortion (THD) on the grid side exceeds 5%, the control unit automatically activates a harmonic suppression algorithm, adjusting the PWM modulation strategy of the active front end to control the THD below 3%. When the junction temperature of the switching transistor exceeds 125°C or the current exceeds 110% of the rated value, a derating mechanism is triggered, gradually reducing the charging power and issuing an alarm signal until the parameters return to normal or the system safely shuts down.

[0066] During modal operation, if the charging voltage requirement fed back by the BMS... Charging current requirements If a change occurs, return to re-evaluate the mode; otherwise, maintain the current mode.

[0067] In one embodiment, a power pre-compensation and capacitor pre-charge / discharge strategy is introduced to suppress power surges and bus voltage fluctuations during mode switching.

[0068] Specifically, the switching to the target operating mode is determined by calculating the power difference based on the power requirements of the target mode and the current mode. Before switching, the power difference is calculated using Formula 10: Formula 10; in, For power deviation, For the power requirements of the target mode, This represents the power requirement for the current mode.

[0069] Adjust the output current of the active front-end (AFE) on the grid side according to the direction of the power difference. If switching to high-power mode, the output current of the upstream AFE is increased in advance to pre-charge the bus capacitor, so that... The AFE will reach 95% of the target mode voltage in advance; if switching to a low-power mode, the AFE will reduce the output current in advance to control the capacitor to discharge slowly and avoid a sudden voltage drop.

[0070] The mode switching action is performed, and during the execution, the first voltage fluctuation is determined by the voltage feedback compensation coefficient, and the first voltage fluctuation is suppressed by closed-loop regulation. During the switching process, the first voltage fluctuation is calculated by Formula 11, and the voltage feedback compensation coefficient is introduced to suppress ΔUdc to within 3% of the rated voltage. Formula 11 is shown below: Formula 11; in, This is the first voltage fluctuation. For power deviation, This represents the total capacitance of the DC bus. This refers to the pre-charging time.

[0071] In one embodiment, a centralized collaborative scheduling strategy is adopted to address the uneven power distribution problem when multiple piles are running in parallel.

[0072] Specifically, the main control unit collects the output power of each flash charging station and calculates the total load and average power, where the total load... The output power of each flash charging station Summing gives the average power. From total load The average value is obtained by taking the total number N.

[0073] Determine the power deviation of each flash charging station; power deviation The output power of each flash charging station With average power We get the difference.

[0074] If there is a designated fast-charging station with a power deviation higher than the second preset deviation value, for example... Then, an instruction is issued to adjust the DC-DC phase shift angle of the designated flash charging station, so that... It converges to within the threshold.

[0075] Based on the obtained total harmonic distortion (THD) of the grid current, the pulse width modulation (PWM) rectification timing of each flash-charging station is adjusted. A grid-side harmonic suppression loop is introduced to monitor the THD of the grid current in real time. By adjusting the PWM modulation timing of each AFE, ≤3%, meeting the relevant requirements.

[0076] In one embodiment, grid voltage fluctuation feedback control is introduced to reduce the impact of high-power charging loads on the power grid.

[0077] Specifically, based on the collected grid node voltages Determine the second voltage fluctuation amount Second voltage fluctuation From the voltage of the power grid nodes Rated voltage of grid node We obtain the difference by finding the absolute value.

[0078] If the second voltage fluctuation is higher than the preset fluctuation, for example... The total charging power of the charging station is dynamically adjusted according to the direction of voltage fluctuations. Power peak shaving is achieved through Formula Twelve. Formula 12; in, This refers to the adjusted total power of the charging station. This refers to the total power of the charging station before the adjustment. A grid-friendliness factor, ranging from 0.5 to 0.7, is used to ensure that the charging load matches the grid capacity. This is the second voltage fluctuation. This refers to the rated voltage of the power grid node.

[0079] Achieving excellent loss control across all operating conditions and improving system energy conversion efficiency: Through multi-modal topology reconstruction, differentiated circuit structures are matched to different voltage and power requirements: low-voltage, low-power modes activate only some circuit modules and reduce switching frequency, thereby reducing switching and conduction losses; low-voltage, high-power and high-voltage, high-power modes fully unleash the capacity potential of power devices through topology optimization using parallel / series capacitors. Compared to traditional fixed-topology flash charging stations, this reduces switching losses in low-voltage, low-power scenarios and improves system conversion efficiency across all operating conditions, effectively addressing the industry pain point of high multi-condition losses in traditional topologies.

[0080] Covering an ultra-wide voltage and power range, compatible with the charging needs of various types of electric vehicles: Three operating modes enable output voltage from 200V to 1000V and output power covering all scenarios from low-power energy replenishment to high-power fast charging. It can meet the fast charging and daily energy replenishment needs of 400V low-voltage platform vehicles, and also adapt to the high-power flash charging needs of 800V high-voltage platform vehicles. There is no need to configure dedicated charging piles for different models, which improves the versatility of charging equipment and site utilization, and solves the problem of narrow voltage and power compatibility of traditional charging piles.

[0081] Achieving smooth mode switching and improving the reliability of the charging system: A collaborative control strategy of power pre-compensation and capacitor pre-charge / discharge is introduced. By adjusting the output of the front-end AFE in advance, the power surge and bus voltage fluctuation during the mode switching process are suppressed, and the DC bus voltage fluctuation is controlled within the preset range of the rated voltage. This avoids current distortion and sudden voltage stress changes in devices during the switching process, extends the service life of power devices, and solves the defects of traditional mode switching technology, such as large impact and poor stability.

[0082] Achieving multi-pile parallel coordination and grid-side friendly interaction supports the large-scale deployment of charging stations: The power balancing control strategy can suppress the power deviation of a single pile during multi-pile parallel operation within a preset range. At the same time, through grid voltage fluctuation feedback control, the total load of the charging station is dynamically adjusted to control the voltage fluctuation of the grid nodes within a preset range, and the total harmonic distortion rate of the grid current is lower than the preset range, meeting the relevant standards for power quality. This avoids harmonic superposition and module overload problems when multiple piles are connected in parallel, and reduces the impact of high-power charging loads on the grid, providing technical support for the large-scale construction of charging stations.

[0083] The various embodiments in this application are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the device and medium embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the description of the method embodiments.

[0084] The above description is merely an embodiment of this application and is not intended to limit the scope of 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 scope of the claims of this application.

Claims

1. A control method for ultra-wide voltage flash charging piles based on multi-level topology reconstruction, characterized in that, include: A hardware system for an ultra-wide voltage flash charging pile based on multi-level topology reconstruction is constructed. The hardware system includes: an active front-end on the grid side, an intermediate topology reconstruction stage, a dual-channel high-frequency isolated DC-DC converter stage, a control unit, a detection module, and a communication module. The detection module collects the system initial parameters corresponding to the hardware system and performs anomaly detection based on the system initial parameters. The control unit collects the vehicle charging demand parameters corresponding to the electric vehicle through the communication module, and determines the operating mode corresponding to the hardware system based on the vehicle charging demand parameters. Closed-loop feedback control is performed based on the operating mode to adjust the modulation ratio of the active front end on the grid side to stabilize the DC bus voltage, configure the switching state of the intermediate topology reconfiguration stage to reconfigure the connection mode of the DC bus capacitor, and adjust the phase shift angle and operating frequency of the subsequent dual-channel high-frequency isolated DC-DC converter stage to match the vehicle charging demand parameters.

2. The method according to claim 1, characterized in that, The active front end on the power grid side includes AC input terminals for phases A, B, and C, and a first switch and a second switch corresponding to each phase; the input terminal of the first switch is connected to the positive terminal of the DC bus, and the output terminal is connected to the AC input of each phase; the input terminal of the second switch is connected to the AC input of each phase, and the output terminal is connected to the negative terminal of the DC bus. The intermediate topology reconfiguration stage includes corresponding third switches, first DC bus capacitors, and second DC bus capacitors; the first DC bus capacitor and the second DC bus capacitor are connected in series, with the upper end of the first DC bus capacitor connected to the positive terminal of the DC bus and the lower end of the second DC bus capacitor connected to the negative terminal of the DC bus; the third switch is a bidirectional switch, connecting each phase AC input to the midpoint of the DC bus; The subsequent dual-channel high-frequency isolated DC-DC converter stage includes two symmetrical parallel branches, each containing a bidirectional full-bridge isolated DC-DC converter and an output filter capacitor. The input terminal of the bidirectional full-bridge isolated DC-DC converter in the first branch corresponding to the first DC bus capacitor is connected to the positive terminal of the DC bus and the midpoint of the DC bus. The input terminal of the bidirectional full-bridge isolated DC-DC converter in the second branch corresponding to the second DC bus capacitor is connected to the negative terminal of the DC bus and the midpoint of the DC bus. The output terminal of the bidirectional full-bridge isolated DC-DC converter in each branch is connected in parallel with its corresponding output filter capacitor.

3. The method according to claim 2, characterized in that, The control unit collects vehicle charging demand parameters corresponding to the electric vehicle through the communication module, and determines the corresponding operating mode of the hardware system based on the vehicle charging demand parameters, specifically including: The control unit collects the vehicle charging demand parameters corresponding to the electric vehicle through the communication module. The vehicle charging demand parameters include charging voltage demand and charging current demand, and the charging power is obtained based on the charging voltage demand and the charging current demand. Based on the vehicle charging demand parameters, a preset threshold is compared to determine the corresponding operating mode of the hardware system; If the charging voltage requirement is lower than a preset voltage threshold and the charging power is lower than a preset power threshold, then the operating mode of the hardware system is determined to be a low-voltage, low-power mode. If the charging voltage requirement is lower than a preset voltage threshold and the charging power is higher than a preset power threshold, then the operating mode of the hardware system is determined to be low voltage high power mode. If the charging voltage requirement is higher than the preset voltage threshold, then the operating mode of the hardware system is determined to be the high-voltage, high-power mode.

4. The method according to claim 3, characterized in that, Closed-loop feedback control based on the aforementioned operating mode specifically includes: The operating mode is determined to be the low-voltage, low-power mode; For the intermediate topology reconfiguration stage, the third switch is normally turned on, the second switch is normally turned off, the first DC bus capacitor is connected to the circuit separately, and the second DC bus capacitor is made to float. For the active front end on the grid side, unity power factor control is initiated, the DC bus voltage is determined according to the charging voltage requirement, and the voltage of the first DC bus capacitor is maintained stable through pulse width modulation. For the subsequent dual-channel high-frequency isolated DC-DC converter stage, the first branch is connected separately, the switching frequency is reduced, and the light-load resonant mode is started. The charging voltage and charging current requirements are achieved through phase shift control.

5. The method according to claim 3, characterized in that, Closed-loop feedback control based on the aforementioned operating mode specifically includes: The operating mode is determined to be the low-voltage high-power mode; For the intermediate topology reconfiguration stage, the second switch is kept normally on, so that the first DC bus capacitor and the second DC bus capacitor are connected in parallel to the circuit; For the active front end on the grid side, constant voltage current limiting control is initiated. The voltage of the first DC bus capacitor and the second DC bus capacitor are detected through the capacitor voltage equalization loop. The voltage of the first DC bus capacitor and the second DC bus capacitor are made consistent by dynamically adjusting the rectified current distribution. For the aforementioned dual-channel high-frequency isolated DC-DC converter stage, the first branch and the second branch are connected. Through the current sharing control strategy, the output current of the first branch and the second branch is detected. By fine-tuning the DC-DC phase shift angle, the deviation of the output current of the first branch and the second branch is made lower than a preset ratio, and the first branch and the second branch are made to work together to operate at full load.

6. The method according to claim 3, characterized in that, Closed-loop feedback control based on the aforementioned operating mode specifically includes: The operating mode is determined to be a high-voltage, high-power mode; For the intermediate topology reconfiguration stage, the second switch is kept normally on, so that the first DC bus capacitor and the second DC bus capacitor are connected in series in the circuit; For the active front end on the grid side, the output voltage is increased to keep the voltages of the first DC bus capacitor and the second DC bus capacitor consistent, and the average current at the midpoint of the DC bus is brought close to 0 by adjusting the pulse width modulation rectification timing. For the subsequent dual-channel high-frequency isolated DC-DC converter stage, the first branch and the second branch are connected, and the bidirectional full-bridge isolated DC-DC converter is made to operate at full power. The high-frequency transformer rectification timing in the bidirectional full-bridge isolated DC-DC converter is finely adjusted according to the charging voltage requirement through a constant power control strategy.

7. The method according to claim 3, characterized in that, Closed-loop feedback control based on the aforementioned operating mode specifically includes: For the low-voltage, low-power mode, the detection module collects the voltage, charging voltage requirement, and charging current requirement of the first DC bus capacitor and feeds them back to the control unit. If any parameter deviates from the target value by more than a preset amount, the modulation ratio and DC-DC phase shift angle of the active front end are finely adjusted to perform closed-loop regulation. For the low-voltage high-power mode, the detection module collects the DC bus current and charging power and feeds them back to the control unit. If there is an overload of the charging power or the voltage deviation between the first DC bus capacitor and the second DC bus capacitor exceeds a first preset deviation value, the current limiting protection and alarm mechanism is activated, and the charging power is finely adjusted. For the high-voltage, high-power mode, the detection module collects grid-side harmonics, DC bus voltage fluctuations, and device operating status, and feeds them back to the control unit for dynamic correction.

8. The method according to claim 1, characterized in that, The method further includes: The switching to the operating mode is determined, and the power difference is obtained based on the power requirements of the target mode and the power requirements of the current mode. Adjust the output current of the active front end on the grid side according to the direction of the power difference; The mode switching action is performed, and during the execution, the first voltage fluctuation is determined by the voltage feedback compensation coefficient, and the first voltage fluctuation is suppressed by closed-loop regulation.

9. The method according to claim 1, characterized in that, The method further includes: The main control unit collects the output power of each flash charging station and calculates the total load and average power. Determine the power deviation of each flash charging station; If there is a designated flash charging station with a power deviation higher than the second preset deviation value, an instruction is issued to adjust the DC-DC phase shift angle of the designated flash charging station; Based on the obtained total harmonic distortion rate of the grid current, adjust the pulse width modulation rectification timing of each flash charging pile.

10. The method according to claim 1, characterized in that, The method further includes: The second voltage fluctuation is determined based on the collected grid node voltages; If the second voltage fluctuation is higher than the preset fluctuation, the total charging power of the charging station is dynamically adjusted according to the direction of the voltage fluctuation.

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