A highway charging resource intelligent scheduling system

Abstract

This invention relates to the field of power Internet of Things and smart distribution network monitoring technology, and discloses a smart scheduling system for highway charging resources. The system includes: a dual-end source-side three-level rectification and busbar construction module, which constructs a bipolar three-wire DC transmission busbar between two service areas; a cross-regional transmission line impedance identification and status sensing module, which calculates the distributed inductance and capacitance parameters of long cables in real time; a terminal multi-port adaptive power routing module, which physically selects the voltage level to suit vehicle demand through a switch matrix; and a distributed parameter resonance locking and drive control module, which locks the operating frequency to the line's intrinsic resonant frequency and uses distributed parameters to achieve soft switching. This invention achieves long-distance energy exchange and voltage adaptive matching through cross-regional interconnection and multi-level routing, and transforms line parasitic parameters into resonant elements, reducing transmission losses.

Description

Technical Field

[0001] This invention relates to the field of power Internet of Things and smart distribution network monitoring technology, specifically a smart scheduling system for highway charging resources. Background Technology

[0002] With the explosive growth in the number of new energy vehicles, highway charging networks have become a key infrastructure for ensuring long-distance intercity travel. However, highway scenarios are characterized by tidal effects and uneven spatial and temporal distribution. Especially during holidays or weekends, there is often a phenomenon where charging stations on one side of the service area are congested with vehicles queuing up, while charging stations on the other side are idle and wasted. This imbalance in resource utilization greatly reduces the overall utilization rate of charging facilities and also exacerbates users' range anxiety.

[0003] To alleviate this contradiction, traditional solutions typically rely on increasing the power capacity of service areas on one side. However, highway service areas are often located in remote areas far from urban load centers, where high-voltage power extraction is costly and time-consuming to construct, and transformer capacity idleness is extremely high during off-peak periods, resulting in poor economic efficiency. Another approach is to build an energy interconnection system across service areas, dispatching idle power resources from one side to the busier side. However, existing cross-regional interconnection technologies face multiple technical bottlenecks in practical engineering applications. First, the physical distance between highway service areas is typically hundreds of meters to several kilometers. Long-distance low-voltage AC transmission suffers from significant voltage drop and reactive power loss, while high-voltage DC transmission, although more efficient, faces the challenge of voltage level matching. Currently, electric vehicle battery voltage platforms are transitioning from 400V to 800V or even higher. Most existing DC charging piles use a fixed output range conversion topology, making it difficult to efficiently accommodate both the high-voltage requirements of long-distance cross-regional transmission and the voltage requirements of different vehicles without adding additional step-up / step-down stages, resulting in low overall system conversion efficiency.

[0004] More importantly, in long-distance DC power supply systems, connecting cables exhibit significant distributed parameter characteristics. Long cables are no longer ideal conductors, but possess non-negligible distributed inductance and capacitance. Most existing charging control technologies are based on lumped parameter models, neglecting the high-frequency resonance problem caused by long transmission lines. When the high-frequency switching action of the terminal power electronic converter couples with the line's intrinsic frequency, severe electromagnetic oscillations can easily occur. This not only causes the switching devices to lose their soft-switching (ZVS) condition, resulting in huge switching losses and heat generation, but can even lead to insulation breakdown due to voltage spikes. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an intelligent scheduling system for highway charging resources, which solves the problems of isolated charging resources between long-distance highway service areas, large cross-regional power transmission losses, and system resonance instability caused by the distributed parameters of long cables.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an intelligent scheduling system for highway charging resources, comprising: The dual-end source-side three-level rectification and bus construction module is set up in two service areas of the highway to convert AC power into three-wire DC power with positive, negative and zero potential, and to construct a bipolar DC transmission bus spanning the two service areas. The cross-regional transmission line impedance identification and status sensing module is connected to the bipolar DC transmission bus and is used to inject high-frequency detection signals into the bipolar DC transmission bus and calculate the distributed inductance and distributed capacitance parameters of the bipolar DC transmission bus based on the collected voltage and current response data. A terminal multi-port adaptive power routing module is set on the charging terminal side. Its input end is connected to the positive bus, negative bus and neutral line of the bipolar DC transmission bus through a controllable switch matrix, and its output end is connected to the vehicle to be charged. It is used to physically select different polarity combinations of the bipolar DC transmission bus according to the voltage requirements of the vehicle to be charged. The distributed parameter resonance locking and drive control module is used to receive the calculated distributed inductance parameters and distributed capacitance parameters, calculate the loop resonant frequency determined by the distributed inductance parameters and distributed capacitance parameters, and control the operating frequency of the terminal multi-port adaptive power routing module to establish a locking relationship with the resonant frequency. Preferably, the system further includes a neutral point imbalance compensation and common mode suppression module, used to monitor and adjust the load balance state of the positive and negative lines of the bipolar DC transmission bus and suppress the common mode circulating current caused by the cross-regional ground potential difference.

[0007] Preferably, the dual-ended source-side three-level rectification and bus construction module is used for: A potential system is established using the neutral line as a zero potential reference point, wherein the positive bus of the bipolar DC transmission bus maintains a positive reference voltage to the neutral line, and the negative bus maintains a negative reference voltage to the neutral line. The bipolar DC transmission bus provides three physical voltage utilization levels based on the potential system, namely the first voltage level formed by the positive bus and the neutral line, the second voltage level formed by the neutral line and the negative bus, and the third voltage level formed by the positive bus and the negative bus. When the highway charging resource intelligent scheduling system is in the cross-regional mutual assistance mode, the dual-end source-side three-level rectifier and bus construction module of the two service areas are electrically connected in parallel through DC circuit breakers to form a ring network structure with dual-end power supply.

[0008] Preferably, the cross-regional transmission line impedance identification and status sensing module is used for: The input impedance of the bipolar DC transmission bus is calculated using the frequency of the injected high-frequency detection signal and the collected voltage and current phasors. Based on the calculated input impedance, the inductance and capacitance per unit length of the bipolar DC transmission bus are analyzed using the characteristic impedance model of the bipolar DC transmission bus. Using the analyzed unit length inductance and unit length capacitance, the equivalent total resonant inductance and equivalent total resonant capacitance of the cross-regional transmission network are calculated in real time by integrating the total length of the bipolar DC transmission bus and superimposing the input parasitic parameters of the terminal multi-port adaptive power routing module. These are then output as controlled object model parameters to the distributed parameter resonance locking and drive control module.

[0009] Preferably, the terminal multi-port adaptive power routing module includes an input selection matrix circuit and an isolated DC-DC converter circuit; The input selection matrix circuit includes a positive selection switch, a neutral selection switch, and a negative selection switch. The positive selection switch is connected between the positive bus and the positive input terminal of the subsequent circuit. The negative selection switch is connected between the negative bus and the negative input terminal of the subsequent circuit. The neutral selection switch is connected between the neutral line and the reference terminal of the subsequent circuit. By controlling the on / off combinations of the positive selection switch, the neutral selection switch, and the negative selection switch, the input circuit can be switched to a positive bus to neutral circuit, a neutral to negative bus circuit, or a positive bus to negative bus circuit, thereby changing the input voltage level at the physical level.

[0010] Preferably, the isolated DC-DC converter circuit is used to perform voltage transformation and electrical isolation on the DC power switched by the input selection matrix circuit, so as to match the charging requirements of the electric vehicle battery.

[0011] Preferably, the terminal multi-port adaptive power routing module further includes a controller, used for: Obtain the battery voltage of the vehicle to be charged; Calculate the absolute value of the difference between the battery voltage and the first voltage level, the second voltage level, and the third voltage level; Select the switch combination corresponding to the voltage level with the smallest absolute value of the difference as the target state; When it is determined that the first voltage level or the second voltage level needs to be connected, the positive bus to neutral line circuit or the neutral line to negative bus circuit is selected based on the real-time load balance between the positive bus and the negative bus.

[0012] Preferably, the distributed parameter resonance locking and drive control module is used for: Calculate the intrinsic resonant frequency of the loop formed by the cross-regional transmission line and the terminal based on the received equivalent total resonant inductance and equivalent total resonant capacitance. The switching frequency of the switching devices in the terminal multi-port adaptive power routing module is controlled so that the switching frequency is within the neighborhood of the intrinsic resonant frequency of the circuit, thereby utilizing the distributed parameters of the cross-regional transmission line as part of the resonant tank circuit to participate in power conversion.

[0013] Preferably, the distributed parameter resonance locking and drive control module is further used for: Real-time monitoring of the instantaneous value of the turn-off current in the resonant tank circuit and the voltage of the currently selected DC bus; Using the monitored instantaneous value of the turn-off current and the DC bus voltage, and in conjunction with the equivalent total resonant inductance, the minimum dead time required to evacuate the junction capacitance charge of the switching device within the dead time is calculated based on the principle of energy conservation. The actual dead time applied to the switching device is set to be greater than or equal to the minimum dead time in order to achieve soft switching using line distribution parameters.

[0014] Preferably, the neutral point imbalance compensation and common mode suppression module is used for: The total output current of the positive bus and the total output current of the negative bus are collected in real time, and the load imbalance is calculated. When the load imbalance exceeds a preset threshold, a compensation current command is generated; Based on the compensation current command, the dual-end source-side three-level rectification and bus construction module is controlled to adjust the action time of the zero-sequence voltage vector, thereby injecting compensation current into the neutral line and forcing the neutral point potential to return to zero potential.

[0015] Preferably, the neutral point imbalance compensation and common mode suppression module is used for: A common-mode equivalent circuit model incorporating cross-regional ground potential differences is established, and the common-mode current in the intelligent scheduling system for highway charging resources is detected. In the control loop of the terminal multi-port adaptive power routing module, virtual impedance control based on the common-mode current is introduced; Based on the virtual impedance control, the phase of the drive pulse of the power converter bridge arm is adjusted so that the power converter exhibits equivalent resistance characteristics in the common mode circuit. The equivalent resistance characteristics are used to attenuate the common mode circulating current in the power supply circuit spanning two service areas.

[0016] Preferably, the bipolar DC transmission bus consists of three high-voltage DC cables with independent insulation layers, which are arranged at a fixed geometric spacing in physical space and extend along the highway path.

[0017] This invention provides an intelligent scheduling system for highway charging resources, which has the following advantages: This invention constructs a bipolar DC transmission bus spanning two service areas and establishes a cross-regional mutual assistance mode, electrically connecting the originally isolated uplink and downlink service area microgrids to form a dual-ended power supply ring network. When one service area experiences overload due to holiday traffic while the other is lightly loaded, the system can control the flow of energy from the lightly loaded side to the heavily loaded side. This effectively alleviates the power supply pressure during peak periods without increasing the rated capacity of individual transformers and reduces the expansion costs of power grid infrastructure.

[0018] This invention incorporates a multi-port adaptive power routing module on the charging terminal side. Utilizing the three physical voltage levels provided by the bipolar bus—positive to neutral, neutral to negative, and positive to negative—it directly selects the optimal combination based on the vehicle's battery voltage requirements. This direct adaptation of physical levels not only reduces cascade conversion losses in the DC / DC converter and improves charging efficiency, but also dynamically adjusts the load balance of the positive and negative buses through an intelligent selection strategy, preventing bus voltage shifts caused by unipolar overload.

[0019] This invention addresses the problem of non-negligible distributed inductance and capacitance caused by long cross-regional transmission distances (kilometer-scale) on highways. By injecting high-frequency detection signals through an impedance identification and state sensing module, the invention analyzes in real time the overall resonant parameters of the cross-regional transmission network, including bus distributed parameters and terminal parasitic parameters. By feeding these parameters back to the drive control module, the terminal-isolated DC / DC resonant converter circuit can adjust its switching frequency in real time according to changes in transmission distance and load, ensuring the system always operates at the optimal resonant point. This achieves soft-switching operation (ZVS / ZCS), reducing switching losses and electromagnetic interference. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall architecture according to an embodiment of the present invention; Figure 2 This is a circuit diagram of a terminal multi-port adaptive power routing module according to an embodiment of the present invention; Figure 3 This is a block diagram illustrating the impedance identification and resonance locking principle according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a cross-regional physical interconnection structure according to an embodiment of the present invention; Figure 5This is a flowchart of an operation control method according to an embodiment of the present invention. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] See Figure 1 This invention provides an intelligent scheduling system for highway charging resources, which may include: a dual-end source-side three-level rectification and bus construction module, a cross-regional transmission line impedance identification and status sensing module, a terminal multi-port adaptive power routing module, a distributed parameter resonance locking and drive control module, and a neutral point imbalance compensation and common-mode suppression module.

[0023] The dual-end source-side three-level rectification and bus construction module is set up in two service areas of the highway to convert AC power into three-wire DC power with positive, negative and zero potential, and to construct a bipolar DC transmission bus spanning the two service areas. The cross-regional transmission line impedance identification and status sensing module is connected to the bipolar DC transmission bus and is used to inject high-frequency detection signals into the bipolar DC transmission bus and calculate the distributed inductance and distributed capacitance parameters of the bipolar DC transmission bus based on the collected voltage and current response data. A terminal multi-port adaptive power routing module is set on the charging terminal side. Its input end is connected to the positive bus, negative bus and neutral line of the bipolar DC transmission bus through a controllable switch matrix, and its output end is connected to the vehicle to be charged. It is used to physically select different polarity combinations of the bipolar DC transmission bus according to the voltage requirements of the vehicle to be charged. The distributed parameter resonance locking and drive control module is used to receive the calculated distributed inductance parameters and distributed capacitance parameters, calculate the loop resonant frequency determined by the distributed inductance parameters and distributed capacitance parameters, and control the operating frequency of the terminal multi-port adaptive power routing module to establish a locking relationship with the resonant frequency. The neutral point imbalance compensation and common mode suppression module is used to monitor and adjust the load balance state of the positive and negative lines of the bipolar DC transmission bus and suppress the common mode circulating current caused by the cross-regional ground potential difference.

[0024] In this embodiment, the cross-regional transmission network refers to the overall electrical object used for resonant parameter calculation, which physically consists of the following two parts: The distributed parameter section, which is the bipolar DC transmission bus connecting the two service areas, contributes the main transmission inductance and capacitance to ground of the system. The lumped parameter section, which is the terminal multi-port adaptive power routing module connected to the end of the bus, has input parasitic parameters (such as the bus capacitance and connection inductance mentioned above) that are non-negligible boundary conditions for the resonant circuit.

[0025] The impedance identification module mathematically synthesizes the parameters of the two parts mentioned above to obtain the equivalent total resonant inductance and equivalent total resonant capacitance, which can truly reflect the physical characteristics of the entire high-frequency resonant circuit, thereby enabling the subsequent control module to accurately lock the resonant frequency.

[0026] In this embodiment, the cross-regional physical interconnection structure is specifically used to connect the power transmission channels of the energy systems of service areas on both sides of the highway. Its physical main body consists of three high-voltage DC cables with independent insulation layers, namely the positive transmission bus, the negative transmission bus, and the neutral transmission line.

[0027] A resonant tank circuit refers to an electrical network that achieves specific frequency selectivity and soft-switching conditions through energy exchange between inductors and capacitors during power conversion.

[0028] Unlike traditional DC / DC converters that rely solely on independently connected external inductors and capacitors to construct resonant circuits, the resonant tank circuit of this invention features distributed parameter multiplexing, and is specifically composed of the following two parts: The distributed parameter part, namely the long-distance bipolar DC transmission bus, utilizes its distributed inductance characteristics at high frequencies as a resonant inductor (or partial resonant inductor) and its distributed capacitance characteristics as a resonant capacitor (or partial resonant capacitor). The lumped parameter section refers to the lumped capacitance and connecting inductance at the input of the terminal multi-port adaptive power routing module.

[0029] The drive control module locks the switching frequency near the intrinsic resonant frequency of the resonant tank circuit, causing the current flowing through the switching device or the voltage across its terminals to change in a sinusoidal pattern, thereby achieving zero-voltage turn-on (ZVS) or zero-current turn-off (ZCS), which greatly reduces switching losses and electromagnetic interference during long-distance transmission.

[0030] like Figure 4As shown, the three high-voltage direct current cables extend along a pre-designed underground utility tunnel or overpass beneath the highway subgrade, maintaining a continuous and fixed geometric spacing in physical space. This fixed geometric spacing configuration is used to construct stable distributed inductance and capacitance characteristics of the line, providing a linear time-invariant physical basis for subsequent impedance identification. The positive transmission bus, negative transmission bus, and neutral transmission line are arranged in a triangular or horizontal straight-line configuration in cross-section and are fixed by non-magnetic insulating supports to suppress electrodynamic displacement between the conductors caused by large currents.

[0031] Each transmission bus utilizes a coaxial cable structure with a metallic shield or a single-core cross-linked polyethylene insulated cable structure. The metallic shield of the cable is cross-connected or single-end grounded at the access points of both service areas via grounding boxes to establish a common-mode current discharge path using a defined grounding method. The insulation withstand voltage rating of the neutral transmission line is the same as that of the positive and negative transmission buses to handle neutral point potential shifts that occur during asymmetrical system operation.

[0032] At the power access boundaries of the service areas on both sides, the positive transmission bus, negative transmission bus, and neutral transmission line are connected in series with a combination of DC fast circuit breaker and disconnector. The DC fast circuit breaker is equipped with bidirectional current breaking capacity and is used to disconnect the physical connection within milliseconds when a short circuit fault or insulation breakdown occurs on the cross-regional transmission line.

[0033] The cross-regional physical interconnection structure also includes an optical fiber composite communication unit laid along the cable path. This optical fiber composite communication unit is laid in the same trench as the three DC cables or integrated inside the cables. It is used to transmit synchronous clock signals and control commands between the source-side modules and terminal modules in the service areas on both sides, ensuring the real-time performance of cross-regional energy dispatch.

[0034] To further eliminate voltage traveling wave reflection oscillations generated during long-distance cross-regional DC transmission, impedance matching termination units are installed at the ends of the positive transmission bus, negative transmission bus, and neutral transmission line (i.e., the end furthest from the source-side converter). These impedance matching termination units consist of a high-voltage non-inductive resistor and an absorption capacitor connected in series. Their characteristic impedance is used to match the characteristic impedance of the transmission line, thereby absorbing reflected wave energy during high-frequency transmission and preventing bus voltage spikes from breaking down the insulation layer of the termination equipment.

[0035] Furthermore, the fiber optic composite communication unit employs industrial real-time Ethernet communication protocols based on EtherCAT or PTP (Precision Time Protocol, IEEE 1588). The system sets up master and slave clock nodes in regions A and B respectively. By measuring the round-trip transmission delay of the optical signal in the inter-regional fiber, phase synchronization correction is performed on the PWM carrier signals of the converters on both sides and all charging terminal controllers along the line, with synchronization accuracy controlled within 1 microsecond. This global clock synchronization mechanism is a necessary prerequisite for achieving coordinated control of distributed parameters across regions and precise power mutual assistance at both ends.

[0036] Cross-regional mutual assistance mode refers to a specific operating state of highway power distribution systems, and its definition includes two aspects: physical connection and power dispatch. At the physical level, this means that the positive bus circuit breaker, negative bus circuit breaker, and neutral disconnect switch between the uplink service area (Area A) and the downlink service area (Area B) are all in a closed state, so that the two service area microgrids, which were originally operating independently, form an electrically connected unified dual-end power supply ring network or chain network through the bipolar DC transmission bus.

[0037] At the power dispatch level, this mode is primarily triggered when a significant load imbalance (i.e., tidal effect) is detected between the two service areas. In this mode, the dual-source three-level rectification and bus construction module is no longer solely responsible for maintaining local voltage stability. Instead, based on a unified power allocation strategy (such as DC voltage droop control or master-slave control), it controls the flow of energy from the lightly loaded service area (i.e., the side with lower load rate and surplus transformer capacity) to the heavily loaded service area (i.e., the side with higher load rate and tighter transformer capacity) via the inter-regional transmission line.

[0038] In this embodiment, the dual-source-side three-level rectification and busbar construction module includes two identical bidirectional AC / DC converters located in Region A (upstream service area) and Region B (downstream service area), respectively. The AC side of each device is connected to the 380V or 10kV AC distribution network of the corresponding service area, and the DC side together form a cross-regional bipolar DC ring network.

[0039] This bidirectional AC / DC converter employs a three-phase, three-level topology. In this embodiment, a neutral point clamped (NPC) three-level rectifier circuit or a T-type three-level rectifier circuit is specifically used. This circuit includes three bridge arms, each consisting of four power semiconductor switching devices and two clamping diodes (for the NPC type), or four power semiconductor switching devices (for the T type). The midpoint of each bridge arm is connected to the three-phase input terminal of the AC power grid, and the DC output side has a positive port, a negative port, and a neutral port formed by the midpoint of the DC-side capacitor. By controlling the conduction state of the switching devices in each bridge arm, the converter can achieve unity power factor operation and adjust the amplitude and polarity of the DC-side output voltage.

[0040] Specifically, the control system of this bidirectional AC / DC converter adopts a voltage and current dual closed-loop control strategy based on a dq rotating coordinate system. The outer loop is the DC bus voltage control loop. The system acquires the positive bus voltage. With negative bus voltage Calculate the total bus voltage Compare the actual value with the given value. After comparison and error calculation by the proportional-integral (PI) regulator, the active current command is output. .

[0041] The inner loop is the grid-side AC current control loop. The system collects the three-phase input current from the AC side and converts it into active components in a synchronous rotating coordinate system through Clark and Park transformations. and reactive components .Will With actual active power In contrast, the reactive current is given (Usually set to 0 to achieve unity power factor) and actual active component In comparison, the errors are decoupled and controlled by the Pl regulator and the grid voltage feedforward to generate dq-axis voltage commands. and .

[0042] Finally, the voltage command is converted into a pulse signal to drive the bridge arm switches via a Space Vector Pulse Width Modulation (SVPWM) module. During SVPWM modulation, redundant small vector selection logic is specifically introduced. For a three-level NPC topology, the output voltage vector space contains 27 basic vectors, some of which (e.g., small vectors) have opposite effects on the DC-side midpoint potential. Based on the polarity of the midpoint potential deviation, the control system dynamically adjusts the time ratio of the small vector's effect within each switching cycle, thereby achieving fine-tuning control of the DC-side midpoint potential without affecting the AC-side current waveform.

[0043] The three-wire DC bus system constructed in this embodiment of the invention includes a positive bus. Negative busbar and neutral line The system defines the neutral line. The potential is the zero potential reference point, that is... The source-side converter establishes a stable potential system on the DC side through a closed-loop control strategy. The unipolar DC reference voltage is set as follows: The voltage between the positive busbar and the neutral line and the positive terminal to ground is... Controlled as: ; Negative bus voltage to neutral line Controlled as: ; Based on the above voltage definition, this bus system provides three discrete voltage utilization levels for subsequent loads at the physical level. The first voltage level... Defined as the absolute value of the potential difference between the positive busbar and the neutral line, i.e.: ; Second voltage level Defined as the absolute value of the potential difference between the neutral line and the negative busbar, i.e.: ; Third voltage level Defined as the absolute value of the potential difference between the positive and negative busbars, i.e.: ; in, The specific value is determined based on the system design; in this embodiment, Set to a constant value within the range of 400V to 500V, so that and Electric vehicles that are compatible with a 400V voltage platform, and This system is compatible with electric vehicles operating on an 800V voltage platform. Its layered architecture allows the system to directly match loads of different voltage levels without requiring a DC / DC boost stage.

[0044] Bus tie switch groups are installed at the DC output ports of Zone A and Zone B, respectively. Each switch group includes a positive circuit breaker, a negative circuit breaker, and a neutral disconnector. The positive circuit breaker is connected in series between the local positive port and the inter-zone positive transmission bus, and the negative circuit breaker is connected in series between the local negative port and the inter-zone negative transmission bus. The neutral disconnector is connected in series between the local neutral port and the inter-zone neutral transmission line. When the system determines that inter-zone power exchange is required, the bus tie switch groups on both sides close, electrically connecting the DC buses of Zone A and Zone B, forming a bipolar ring network structure with dual-ended power supply. When the system determines that a unilateral fault has occurred or that independent operation is required, the corresponding bus tie switch group opens, achieving physical isolation.

[0045] In this embodiment, the cross-regional transmission line impedance identification and status sensing module includes a high-frequency signal injection unit, a data acquisition front-end, and a distributed parameter calculation processor.

[0046] A high-frequency signal injection unit is coupled to the beginning of the cross-region DC bus, specifically between the positive bus and the neutral line, or between the negative bus and the neutral line. This high-frequency signal injection unit includes a high-frequency signal generator and an injection isolation transformer, used to periodically superimpose small-amplitude, frequency-adjustable sinusoidal probe signals or pseudo-random sequence signals onto the operating DC bus. The frequency range of the injected signal covers the system's estimated resonant frequency band.

[0047] In this embodiment, the high-frequency probe signal refers to a tiny AC disturbance signal superimposed on the DC bus to identify the high-frequency impedance characteristics of the line. Its waveform can specifically be a frequency-adjustable sine wave scanning signal or a pseudo-random binary sequence (PRBS) signal.

[0048] To ensure accurate excitation of the distributed parameter effects of the line without affecting the normal power transmission of the DC bus, the parameter range of the high-frequency detection signal is limited as follows: The frequency range is set from 1kHz to 500kHz. This range covers the first and second intrinsic resonant frequencies of long-distance cables (typically between 500 meters and 5 kilometers in length) and can effectively avoid power frequency (50Hz / 60Hz) and low-frequency ripple interference from source-side converters.

[0049] The amplitude range is set to 0.5% to 2% of the rated DC bus voltage (e.g., for an 800V bus, the injected signal amplitude is 4V to 16V). This small amplitude is sufficient to be detected by a highly sensitive current transformer without triggering the system's overvoltage / undervoltage protection.

[0050] The injection method can be differential mode injection (positive to negative) or common mode injection (positive / negative to ground). In this embodiment, the positive busbar to neutral line injection method is preferred.

[0051] The characteristic impedance model of a transmission line is constructed based on the theory of long-line transmission. Specifically, for a length of... The bipolar DC transmission bus, neglecting line resistance and conductance (loss is negligible under high-frequency injected signals), has the characteristic impedance... With propagation constant The mathematical expression is: ; in, Inductance per unit length Capacitance per unit length The angular frequency of the injected high-frequency detection signal.

[0052] The processor uses the acquired voltage phasor With current phasor Calculate the input impedance of the bus. .

[0053] The data acquisition front end includes high-bandwidth voltage transformers and current transformers, installed at the signal injection point and end node of the cross-regional transmission line, respectively. The voltage transformers are used to acquire the voltage response waveform on the bus, and the current transformers are used to acquire the current response waveform on the bus. The acquired analog signals are converted into digital sequences by an analog-to-digital converter and transmitted to a distributed parameter processing processor. The processor performs a Fast Fourier Transform (FFT) on the voltage and current data to extract the amplitude and phase information of the fundamental component at a specific injection frequency.

[0054] To improve identification accuracy in environments with strong electromagnetic interference, multiple digital filtering and windowing algorithms are employed in the signal acquisition and processing. First, before the analog signal enters the ADC, a second-order Butterworth low-pass filter removes high-frequency noise above the switching frequency (e.g., above 50kHz) to prevent aliasing. The ADC sampling frequency is set to at least 20 times the injected signal frequency. In the digital signal processing stage, the processor applies a Hanning window function to weight the acquired discrete voltage and current sequences to suppress spectral leakage caused by aperiodic truncation.

[0055] Subsequently, a sliding window algorithm based on Discrete Fourier Transform (DFT) was employed to target the injected frequency points. Single-point spectrum analysis was performed. To eliminate background noise interference generated by the switching action of the DC / DC converter on the DC bus, the system employed a differential injection method: in Record the background noise spectrum without injecting any signal. ;exist Inject signals at regular intervals and record the total spectrum. The processor uses vector subtraction to remove background noise. ; Based on the purified signal phasor The calculated impedance value is then filtered using a five-point moving average filter, ultimately serving as the basis for calculating effective distributed parameters. This processing method ensures that the inductance per unit length is minimized under bus load operation conditions. The identification error is controlled within 5%.

[0056] The distributed parameter calculation processor, based on a transmission line theory model, calculates the distributed parameters of cross-regional transmission lines in real time using acquired frequency domain data. First, the processor calculates the distributed parameters based on the injected frequency. Voltage phasors under With current phasor Calculate the input impedance of the transmission line. Subsequently, based on the characteristic impedance equation of the transmission line, the inductance per unit length of the line was analytically derived. and capacitance per unit length Based on this, the processor calculates the equivalent total resonant inductance of the entire inter-regional transmission system. With equivalent total resonant capacitance Equivalent total resonant inductance The calculation formula is: ; in, Indicates the total physical length of the inter-regional transmission line. Indicates position Inductance distribution function per unit length at a given location, This represents the additional inductance value of the filter reactors and connecting cables connected in series at both ends of the line. Equivalent total resonant capacitance. The calculation formula is: ; in, Indicates position The capacitance distribution function per unit length at a given location, This represents the sum of the output parasitic capacitances of all terminal power switching devices currently connected to the DC bus. Through the above calculations, this module transforms the physical properties of long-haul cables and their auxiliary equipment across regions into a lumped parameter model. and This provides accurate controlled object model parameters for subsequent resonant frequency locking control. This process is performed periodically to update parameter drift caused by temperature changes or variations in the number of connected devices.

[0057] like Figure 2 As shown, in this embodiment, the terminal multi-port adaptive power routing module is set in the power cabinet corresponding to each charging space. The module includes an input selection matrix circuit, an isolated DC / DC resonant converter circuit, and a local controller.

[0058] The input selection matrix circuit is located at the very front of the module and is directly connected to the three-wire DC bus. This input selection matrix circuit consists of three high-voltage power semiconductor switching devices, namely a positive selection switch. Neutral line selection switch and negative selection switch Positive selection switch One end is connected to the positive transmission bus of the system. The other end is connected to the positive input terminal of the subsequent power conversion circuit. Neutral line selector switch. One end is connected to the system's neutral transmission line The other end, via a single-pole double-throw switching mechanism or a bidirectional blocking branch consisting of two inverted series switching devices, is connected to the positive or negative input terminal of the subsequent power conversion circuit through a controllable path, or to the common reference terminal of the subsequent power conversion circuit. Negative selection switch. One end is connected to the negative transmission bus of the system. The other end is connected to the negative input terminal of the subsequent power conversion circuit. The three gating switches employ insulated-gate bipolar transistors (IGBTs) or silicon carbide metal-oxide-semiconductor field-effect transistors with reverse blocking capability. By combining and controlling the on / off states of these three gating switches, the physical connection of the input terminal can be switched to... loop, circuit or The circuit thus changes the physical level of the input voltage.

[0059] To prevent bus short circuits or arcing when switching between different voltage levels, the input selection matrix circuit operates in strict order of disconnection before connection and soft-start timing logic.

[0060] When executing a topology reconfiguration command, the local controller first blocks all drive pulses of the downstream DC / DC converter, reducing its current to zero. Subsequently, the controller disconnects the currently active gating switch (e.g., disconnecting before switching to) and introduces a mechanical / electrical dead time of 20ms to 50ms to wait for the switch contacts to completely separate and the arc to extinguish.

[0061] Before closing the new target switch, the controller activates and completes the pre-charging process within 100ms. This process pre-charges the DC bus capacitor of the subsequent power conversion circuit through a pre-charging resistor connected in parallel across the selector switch and the auxiliary relay branch. The main power switch is closed only when the voltage difference between the capacitor and the target bus voltage is detected to be less than a preset threshold (e.g., 10V), and then the pre-charging branch is bypassed.

[0062] In addition, each selector switch , , , Hardware interlocking logic is provided between the drive circuits. If a detection is made... and Simultaneously, it has a high-level drive signal (i.e., in the event of a shoot-through short circuit risk). The hardware protection circuit will forcibly pull down all gate voltages within microseconds and trigger a system-level fault alarm, physically eliminating the three-wire short circuit accident caused by human error or software malfunction.

[0063] An isolated DC / DC resonant converter circuit is connected to the output side of the input selection matrix circuit. This circuit employs a full-bridge LLC resonant topology or a phase-shifted full-bridge (PSFB) topology. Its primary-side H-bridge circuit is connected to the DC bus output from the input selection matrix circuit, and the AC output terminal of the primary-side H-bridge is connected to the resonant tank circuit and the primary winding of the high-frequency isolation transformer. The secondary winding of the high-frequency isolation transformer is connected to the rectifier and filter circuit, ultimately outputting to the battery port of the electric vehicle. This isolated DC / DC resonant converter circuit preferably uses a bidirectional CLLC resonant topology. This topology has resonant capacitors and resonant inductors symmetrically arranged on both the primary and secondary sides of the transformer. Specifically, in this embodiment, the primary-side resonant inductor... The design does not use independent magnetic components, but instead reuses the equivalent inductance of the cross-region transmission line identified by the distributed parameter resonant lock-in and drive control module. Part or all of it. In specific design, the controller is based on the current... Value, dynamically adjust the quality factor of the resonant tank circuit. Transformer turns ratio Designed as ,in Reference bus voltage , This is the reference battery voltage.

[0064] When the input selection matrix switches voltage levels (e.g., from...), Switch to 2 The operating mode of the subsequent power conversion circuit then switches from full-bridge mode to half-bridge mode, or by changing the series and parallel combination of the transformer primary windings, the equivalent turns ratio is halved. This ensures that even when the input voltage doubles, the output voltage range still covers the vehicle battery requirements, and the converter always operates at the optimal gain point. ≈1.

[0065] The local controller executes voltage ladder matching control logic to determine the operating state of each switch in the input selection matrix circuit. The controller first reads the battery rated voltage requirement sent by the battery management system (BMS) of the vehicle to be charged via the communication interface. Subsequently, the controller defines the input state vector. The element has a value of 1 indicating conduction and 0 indicating deactivation. The controller is based on a preset objective function. Calculate the optimal switching combination; the objective function aims to minimize the input voltage. With battery voltage The absolute value of the difference between them: ; Among them, input voltage The calculation relationship is as follows: ; The specific control strategy is as follows: when the discrimination result indicates... Within the first voltage level range (e.g., close to) When ), the controller outputs a command to make (i.e., conduction) and Connect the positive bus and the neutral line; or output a command to make (i.e., conduction) and Connect the neutral and negative busbars. This selection is further determined based on the real-time load balancing of the positive and negative buses. When the judgment result shows... In the second voltage level range (e.g., close to 2) When ), the controller outputs a command to make (i.e., conduction) and The circuit connects to the positive and negative bus. This logic ensures a rough physical match between the converter input voltage and the battery voltage, allowing the subsequent DC / DC converter to always operate in a high-efficiency range where the voltage gain is close to 1.

[0066] like Figure 3 As shown, in this embodiment, the distributed parameter resonance locking and drive control module is implemented by a digital signal processor, and its control object is the DC / DC converter switch in the terminal power routing module.

[0067] The distributed parameter resonance locking and drive control module first receives the system's equivalent total resonant inductance, which is calculated in real time by the cross-regional transmission line impedance identification module. and equivalent total resonant capacitance Based on these two physical parameters, this module calculates the intrinsic resonant frequency of the loop formed by the current inter-regional transmission system and the terminal. The calculation formula is: ; Subsequently, the frequency synthesizer inside this module will generate the fundamental switching frequency of the DC / DC converter. Locking to the neighborhood of this intrinsic resonant frequency. Specifically, setting the frequency tracking coefficient. Control the switching frequency satisfy: ; Among them, coefficient A value slightly greater than 1 (e.g., 1.05 to 1.1) is set to ensure that the resonant tank circuit exhibits inductive impedance characteristics, which is necessary for achieving zero-voltage turn-on. This frequency locking mechanism allows the control system to adaptively adjust the operating frequency according to changes in the length of the cross-section cable or the number of parallel vehicles, always utilizing the line distribution parameters as the resonant element rather than being interfered with by them.

[0068] The implementation of frequency tracking control relies on digital phase-locked loop (DPLL) technology. A virtual oscillator is built internally by the controller, referencing a distributed parameter model.

[0069] When the equivalent total resonant inductance is identified With equivalent total resonant capacitance Changes (e.g., due to changes in the length of the access cable) (Cause), the controller calculates a new target frequency .

[0070] To avoid system oscillations caused by sudden frequency changes, the frequency is adjusted using a gradual ramp method, set as follows: Within 500Hz / ms.

[0071] Simultaneously, the controller sets a frequency lock-in safety boundary. The system's permissible operating frequency range is defined as follows: For example, 50 Up to 150 If the calculated If the signal exceeds this range, the controller will no longer perform frequency locking, but will switch to fixed-frequency PWM mode and control the power by adjusting the phase shift angle, while simultaneously issuing a line parameter abnormality alarm. Furthermore, in multi-vehicle parallel charging scenarios, the parallel connection of the input capacitors of multiple terminals will increase the total capacitance... As the frequency increases, the resonant frequency decreases. The controller executes a distributed frequency coordination strategy: each terminal controller shares its own switching frequency through fiber optic communication, the main controller calculates the weighted average frequency or specifies a unified master synchronization frequency, and each sub-controller uses phase shifting (interleaving) technology to stagger the switching actions of each terminal on the time axis. This not only utilizes distributed inductance to achieve ZVS, but also utilizes multiphase interleaving technology to eliminate the total current ripple on the bus.

[0072] Determining the switching frequency Based on this, the module further controls the dead time of the switching transistor drive signal. This enables zero-voltage switching (ZVS). The module monitors the instantaneous value of the turn-off current in the resonant tank circuit in real time. and the currently selected DC bus voltage According to the principle of energy conservation, to ensure that the inductor's stored energy is sufficient to deplete the charge on the switch junction capacitor within the dead time, the control logic must satisfy the energy constraint condition: ; Based on this constraint, the module calculation can achieve the minimum dead time required for soft switching. : ; The controller will actually apply the dead time to the switching transistor. Set to greater than or equal to The value is [value missing]. Through this mechanism, the soft switching action of the power device is assisted, thereby eliminating the switching losses and electromagnetic interference caused by high-frequency hard switching.

[0073] In this embodiment, the neutral point imbalance compensation and common mode suppression module is integrated into the central controller and the source-side converter control loop to maintain the electrical stability of the bipolar DC bus.

[0074] The neutral point imbalance compensation and common mode suppression module collects the total output current of the positive bus in real time. Total output current of the negative bus This module calculates the load imbalance. and compare it with a preset threshold. Comparison. When detected. This indicates that when a severe imbalance in the positive and negative loads causes a shift in the neutral point potential, the module activates an active balancing control strategy, which generates a compensation current command. Its control law is designed as follows: ; in, This is the voltage between the positive terminal and ground. This is the negative voltage to ground. and These are the proportional and integral coefficients, respectively. This command is sent to the control unit of the source-side three-level converter. The control unit adjusts the duration of the zero-sequence voltage vector accordingly, controlling the injection of compensation current from the converter's neutral point to the neutral line, forcing the neutral point potential back to near zero potential, thus achieving… .

[0075] To address potential ground potential difference interference that may be introduced by long-distance interconnections across regions, this module implements active damping control of common-mode circulating current. The module first establishes a common-mode equivalent circuit model, where the common-mode voltage source... Defined as: ; in This represents the ground potential difference between the grounding points in region A and region B. This is to suppress the resulting common-mode current. The module introduces virtual impedance control into the control loop of the terminal DC / DC converter. Specifically, the module adjusts the phase difference of the drive pulses of the diagonal arms in the full-bridge circuit of the converter, making them exhibit equivalent resistance characteristics in the common-mode circuit. This equivalent active damping resistor... The resistance value must be set to meet the boundary conditions derived from the Nyquist stability criterion: ; in This is the maximum permissible common-mode current safety limit for the system. By dynamically adjusting the phase of the drive pulse, the system exhibits high impedance characteristics in the common-mode frequency band, thereby effectively attenuating the common-mode circulating current flowing in long-distance cross-regional interconnection structures and preventing it from causing malfunctions of protection devices or excessive electromagnetic interference.

[0076] Virtual impedance The physical implementation is achieved by modifying the modulation waves of the four bridge arms of the DC / DC converter. For a full-bridge topology, let the midpoint voltages of the four bridge arms be respectively... The common-mode voltage component is mainly composed of... Decide.

[0077] The controller is under normal differential voltage command. Based on this, a common-mode suppression component is superimposed. This component is determined by the detected common-mode current. After passing through a high-pass filter (with a cutoff frequency set to 50Hz to isolate DC bias), multiplied by the equivalent active damping resistance. get, The final duty cycle command applied to each bridge arm. ( Revised to: ; In this way, the converter is electrically equivalent to having a resistor connected in series in the common-mode circuit. A resistor that only works against high-frequency common-mode noise and does not consume DC power. Experimental data shows that when set... When the current is 50Ω, the attenuation rate of the high-frequency common-mode circulating current caused by the cross-regional grounding system can reach more than 20dB, which effectively ensures the electromagnetic compatibility (EMC) of the bipolar system in complex grounding environments.

[0078] like Figure 5 As shown, this embodiment of the invention provides an operation control method for an intelligent scheduling system for highway charging resources. The method covers the entire process from system startup and vehicle access matching to dynamic power transmission, specifically including system initialization and topology self-test steps, vehicle access and voltage adaptation steps, distributed parameter identification and frequency locking steps, and power soft start and dynamic optimization steps.

[0079] After the system is powered on, the source-side AC / DC converter is started first to establish a stable bipolar DC bus voltage system, ensuring the positive bus voltage. Negative bus voltage and neutral line voltage Stable at respectively , and 0 potential.

[0080] Subsequently, the source-side controller executes a topology self-test procedure, injecting a weak high-frequency test signal into the bus. Terminal controllers distributed at each charging station detect the arrival of this test signal. If all terminals can correctly receive the signal and the signal attenuation is within a preset range, it confirms that the cross-regional physical line connectivity is good and there is no insulation or grounding fault; if an abnormal signal is detected, the system will locate the faulty section and isolate the corresponding bus circuit breaker.

[0081] When an electric vehicle connects to a charging terminal, the terminal controller reads the battery status information sent by the vehicle's battery management system (BMS) through the charging communication protocol to obtain the current battery voltage. Rated voltage and maximum allowable charging current The controller performs voltage physical level matching decisions. First, it calculates the battery voltage and its relationship to the first voltage level (…). ) and the second voltage level ( The matching error.

[0082] If the judgment result is This indicates that the vehicle is compatible with the semi-pressure stratification. At this point, the system further queries the load rate of the source-side positive bus. With negative bus load rate .like (in If the set imbalance threshold is met, the control input selection matrix circuit closes the neutral line gating switch. Negative selection switch Connect the vehicle The circuit is closed; otherwise, the positive selector switch is closed by default. Neutral line selector switch Connect the vehicle loop.

[0083] If the judgment result is This indicates that the vehicle is compatible with the full-pressure level, and the controller directly commands the positive selection switch to close. Negative selection switch Connect the vehicle Circuit. During the decision-making and execution process, the timing logic of pre-charging followed by closing is followed to prevent inrush current during closing.

[0084] After selecting the physical circuit and closing the corresponding switch, but before the main power transmission begins, the system performs precise distributed parameter identification. A probe signal containing specific spectral components is injected at the source side, and the cross-regional transmission line impedance identification module collects the response data to calculate the equivalent total resonant inductance of the current circuit in real time. With equivalent total resonant capacitance The terminal controller calculates the intrinsic resonant frequency of the circuit based on the identification results. : ; Subsequently, the controller will adjust the switching frequency of the terminal DC / DC converter. Set as And calculate the minimum dead time that satisfies the zero-voltage turn-on (ZVS) condition. Complete the initial configuration of the soft switch parameters.

[0085] The DC / DC converter begins power transfer, and the output current rises from zero to the target value according to a preset slope. During charging operation, the system monitors the neutral point potential deviation and common-mode current amplitude in real time at a fixed control cycle (e.g., 100ms).

[0086] If a neutral point potential shift is detected If the allowable range is exceeded, the source-side controller adjusts the duration of the small vector in the space vector pulse width modulation (SVPWM) and injects compensation current to balance the midpoint potential.

[0087] If common-mode current is detected If the safety limit is exceeded, the terminal controller adds a virtual damping resistor to the converter control loop. Common-mode circulating current is suppressed by correcting the phase of the bridge arm drive pulse. Simultaneously, the system continuously monitors the temperature rise and efficiency of the DC / DC converter. If changes in ambient temperature cause drift in the distributed line parameters, leading to loss of ZVS status (manifested as efficiency degradation), the controller will fine-tune the switching frequency. The system re-locks a new resonant operating point to ensure efficient transmission throughout the entire process. After charging is complete, the terminal controller disconnects all gating switches and resets to standby mode.

[0088] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A smart scheduling system for highway charging resources, characterized in that, include: The dual-end source-side three-level rectification and bus construction module is set up in two service areas of the highway to convert AC power into three-wire DC power with positive, negative and zero potential, and to construct a bipolar DC transmission bus spanning the two service areas. The cross-regional transmission line impedance identification and status sensing module is connected to the bipolar DC transmission bus and is used to inject high-frequency detection signals into the bipolar DC transmission bus and calculate the distributed inductance and distributed capacitance parameters of the bipolar DC transmission bus based on the collected voltage and current response data. A terminal multi-port adaptive power routing module is set on the charging terminal side. Its input end is connected to the positive bus, negative bus and neutral line of the bipolar DC transmission bus through a controllable switch matrix, and its output end is connected to the vehicle to be charged. It is used to physically select different polarity combinations of the bipolar DC transmission bus according to the voltage requirements of the vehicle to be charged. The distributed parameter resonance locking and drive control module is used to receive the calculated distributed inductance parameters and distributed capacitance parameters, calculate the loop resonant frequency determined by the distributed inductance parameters and distributed capacitance parameters, and control the operating frequency of the terminal multi-port adaptive power routing module to establish a locking relationship with the resonant frequency.

2. The system according to claim 1, characterized in that, The dual-terminal source-side three-level rectification and bus construction module is used for: A potential system is established using the neutral line as a zero potential reference point, wherein the positive bus of the bipolar DC transmission bus maintains a positive reference voltage to the neutral line, and the negative bus maintains a negative reference voltage to the neutral line. The bipolar DC transmission bus provides three physical voltage utilization levels based on the potential system, namely the first voltage level formed by the positive bus and the neutral line, the second voltage level formed by the neutral line and the negative bus, and the third voltage level formed by the positive bus and the negative bus. When the highway charging resource intelligent scheduling system is in the cross-regional mutual assistance mode, the dual-end source-side three-level rectifier and bus construction module of the two service areas are electrically connected in parallel through DC circuit breakers to form a ring network structure with dual-end power supply.

3. The system according to claim 1, characterized in that, The cross-regional transmission line impedance identification and status sensing module is used for: The input impedance of the bipolar DC transmission bus is calculated using the frequency of the injected high-frequency detection signal and the collected voltage and current phasors. Based on the calculated input impedance, the inductance and capacitance per unit length of the bipolar DC transmission bus are analyzed using the characteristic impedance model of the bipolar DC transmission bus. Using the analyzed unit length inductance and unit length capacitance, the equivalent total resonant inductance and equivalent total resonant capacitance of the cross-regional transmission network are calculated in real time by integrating the total length of the bipolar DC transmission bus and superimposing the input parasitic parameters of the terminal multi-port adaptive power routing module. These are then output as controlled object model parameters to the distributed parameter resonance locking and drive control module.

4. The system according to claim 1, characterized in that, The terminal multi-port adaptive power routing module includes an input selection matrix circuit and an isolated DC-DC converter circuit; The input selection matrix circuit includes a positive selection switch, a neutral selection switch, and a negative selection switch. The positive selection switch is connected between the positive bus and the positive input terminal of the subsequent circuit. The negative selection switch is connected between the negative bus and the negative input terminal of the subsequent circuit. The neutral selection switch is connected between the neutral line and the reference terminal of the subsequent circuit. By controlling the on / off combinations of the positive selection switch, the neutral selection switch, and the negative selection switch, the input circuit can be switched to a positive bus to neutral circuit, a neutral to negative bus circuit, or a positive bus to negative bus circuit, thereby changing the input voltage level at the physical level.

5. The system according to claim 2, characterized in that, The terminal multi-port adaptive power routing module also includes a controller for: Obtain the battery voltage of the vehicle to be charged; Calculate the absolute value of the difference between the battery voltage and the first voltage level, the second voltage level, and the third voltage level; Select the switch combination corresponding to the voltage level with the smallest absolute value of the difference as the target state; When it is determined that the first voltage level or the second voltage level needs to be connected, the positive bus to neutral line circuit or the neutral line to negative bus circuit is selected based on the real-time load balance between the positive bus and the negative bus.

6. The system according to claim 3, characterized in that, The distributed parameter resonance locking and drive control module is used for: Calculate the intrinsic resonant frequency of the loop formed by the cross-regional transmission line and the terminal based on the received equivalent total resonant inductance and equivalent total resonant capacitance. The switching frequency of the switching devices in the terminal multi-port adaptive power routing module is controlled so that the switching frequency is within the neighborhood of the intrinsic resonant frequency of the circuit, thereby utilizing the distributed parameters of the cross-regional transmission line as part of the resonant tank circuit to participate in power conversion.

7. The system according to claim 6, characterized in that, The distributed parameter resonance locking and drive control module is also used for: Real-time monitoring of the instantaneous value of the turn-off current in the resonant tank circuit and the voltage of the currently selected DC bus; Using the monitored instantaneous value of the turn-off current and the DC bus voltage, and in conjunction with the equivalent total resonant inductance, the minimum dead time required to evacuate the junction capacitance charge of the switching device within the dead time is calculated based on the principle of energy conservation. The actual dead time applied to the switching device is set to be greater than or equal to the minimum dead time in order to achieve soft switching using line distribution parameters.

8. The system according to claim 1, characterized in that, Also includes: The neutral point imbalance compensation and common mode suppression module is used to monitor and adjust the load balance state of the positive and negative lines of the bipolar DC transmission bus and suppress the common mode circulating current caused by the cross-regional ground potential difference.

9. The system according to claim 8, characterized in that, The neutral point imbalance compensation and common mode suppression module is used for: The total output current of the positive bus and the total output current of the negative bus are collected in real time, and the load imbalance is calculated. When the load imbalance exceeds a preset threshold, a compensation current command is generated; Based on the compensation current command, the dual-end source-side three-level rectification and bus construction module is controlled to adjust the action time of the zero-sequence voltage vector, thereby injecting compensation current into the neutral line and forcing the neutral point potential to return to zero potential.

10. The system according to claim 8, characterized in that, The neutral point imbalance compensation and common mode suppression module is used for: A common-mode equivalent circuit model incorporating cross-regional ground potential differences is established, and the common-mode current in the intelligent scheduling system for highway charging resources is detected. In the control loop of the terminal multi-port adaptive power routing module, virtual impedance control based on the common-mode current is introduced; Based on the virtual impedance control, the phase of the drive pulse of the power converter bridge arm is adjusted so that the power converter exhibits equivalent resistance characteristics in the common mode circuit. The equivalent resistance characteristics are used to attenuate the common mode circulating current in the power supply circuit spanning two service areas.

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