A current adaptive control system and device for electric vehicle charging

Abstract

The application discloses a current adaptive control system and device for electric vehicle charging, and relates to the technical field of electric vehicle charging control. The system collects temperature data of preset weak positions in the electric vehicle charging loop through a negative temperature coefficient thermistor array on a charging gun and a cable; based on local voltage drops and loop current data obtained by paired differential voltage sampling points, local resistances of each node are preliminarily estimated; the local resistances are corrected according to the temperature data to obtain corrected resistance values, and after a predetermined time window controlled current excitation is applied, the corrected resistance values are verified and modified in combination with temperature responses to obtain modified resistance values; based on the modified resistance values, maximum allowed current values of each sampling node are determined, the minimum value is taken as a maximum safe current limit of the charging loop, and phase control and / or periodic on-off control are adopted within the maximum safe current limit to realize charging loop current limiting control, thereby improving the safety and reliability of the electric vehicle charging process.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle charging control technology, and in particular to a current adaptive control system and device for electric vehicle charging. Background Technology

[0002] With the rapid growth of electric vehicle ownership, charging piles and charging guns, as important components of daily energy replenishment for new energy vehicles, are widely used in daily charging scenarios such as residential communities, office parks, and commercial facilities. Their core charging principle is that the charging pile outputs AC power, which is then converted into DC power by the vehicle's onboard charger to replenish the chemical energy of the power battery. The entire process requires coordinated matching between charging equipment, charging cables, and the vehicle's battery management system to balance charging efficiency and safety performance.

[0003] For example, the Chinese invention patent CN109861331B discloses a high-efficiency charging control device and its control strategy for pure electric vehicles. The high-efficiency charging control device for pure electric vehicles includes: a charging device, a charging interface, a charger, and a battery. The charger and battery are connected to a battery management system. The charger, battery, and battery management system are respectively located inside the pure electric vehicle. The charging device is connected to an output current capability acquisition device, and the charging interface is connected to a current-bearing acquisition device. The output current capability acquisition device and the current-bearing acquisition device are respectively connected to the battery management system. A conductor grounding wire is also connected between the charging device, the charging interface, and the pure electric vehicle.

[0004] The control strategy corresponding to this device includes: acquiring the duty cycle of the pulse width modulation (PWM) signal output by the charging equipment; calculating the AC current output capability value of the charging equipment; acquiring the resistance value of the acquisition resistor (RC) in the charging interface and determining the current tolerance limit of the charging interface; determining the maximum AC charging current value by comparing the AC current output capability value and the current tolerance limit value; determining the battery's required charging current based on the maximum AC charging current value; transmitting the calculated battery's required charging current to the charger via a message through the Controller Area Network (CAN) bus, and adjusting the output current to charge the battery according to the received message.

[0005] The aforementioned existing technical solutions establish an AC charging current negotiation and safety protection framework, meeting the charging coordination requirements. However, they often struggle to promptly and accurately identify potential hazards such as localized overheating and increased contact resistance caused by the thinnest parts of the cable or areas with reduced cross-sectional area (e.g., thinning of the conductor due to manufacturing defects, poor crimping, bending wear, localized corrosion, or long-term thermal aging). Abnormal temperatures of the entire cable or casing are usually only detected after localized overheating has reached a certain level, exhibiting a delayed response and inability to provide early real-time protection.

[0006] Furthermore, the charging current setting is mostly based on the rated capacity of the charging equipment or the allowable value at the vehicle end. It lacks the ability to assess the minimum load-bearing capacity of the actual connecting cable under field conditions (including local damage, connection quality, and ambient temperature). Even if the system has temperature alarm or automatic derating functions, such functions usually rely on single-point sensor position or overall power measurement, making it difficult to identify and locate weak segmental defects inside the cable or at the connection. Moreover, it cannot work effectively when the sensor fails or there is a monitoring blind spot.

[0007] It is evident that existing technologies are significantly inadequate in addressing safety risks caused by insufficient cross-sectional area or localized contact issues in cables. On the one hand, there is a lack of online detection methods for the current-carrying capacity of the thinnest part of the cable, which cannot quantify and provide feedback on the actual load-bearing limit of this weakest link in real time. On the other hand, there is a lack of automated current regulation mechanisms based on the detection results, which means that localized defects may continue to bear high currents before being detected in time, leading to overheating, insulation aging, fire, or increased risk of electric shock, thereby affecting the safety and reliability of the electric vehicle charging process. Summary of the Invention

[0008] To address the technical problems in the prior art, embodiments of the present invention provide a current adaptive control system and device for electric vehicle charging. The technical solution is as follows:

[0009] On one hand, a current adaptive control system for electric vehicle charging is provided. This system includes: a multi-node state sensing module, used to collect temperature data from multiple sampling nodes in real time via a negative temperature coefficient thermistor temperature sensor array deployed on the electric vehicle charging gun and / or charging cable; and to preliminarily estimate the local resistance of each sampling node based on the local voltage drop data collected from preset differential voltage sampling points corresponding to each sampling node and the current data of the charging circuit; wherein, the differential voltage sampling points are arranged in pairs and electrically connected to the two ends of a preset measured segment in the conductive path of the charging circuit to obtain the local voltage drop of the preset measured segment; the sampling nodes are preset weak points in the conductive path of the charging gun connector and / or charging cable; and a pulse thermal verification module, used for... The local resistance is preliminarily estimated based on temperature data to obtain a corrected resistance value. After applying a controlled current excitation for a predetermined time window to the charging circuit, the corrected resistance value is verified and corrected based on the temperature response of each sampling node under short-term current excitation to obtain the corrected resistance value of each sampling node. The current carrying limit control module is used to determine the maximum allowable current carrying value of each sampling node based on the corrected resistance value of each sampling node, and take the minimum value of the maximum allowable current carrying value of all sampling nodes as the maximum safe current carrying limit of the corresponding charging circuit during the charging process of electric vehicle. The dynamic current control module is used to perform current limiting control on the charging circuit within the maximum safe current carrying limit. The current limiting control includes at least one of phase control and / or periodic on / off control.

[0010] On the other hand, a current adaptive control device for electric vehicle charging is provided. This device includes: a negative temperature coefficient thermistor temperature sensor array, a differential voltage sampling unit, a current measurement unit, a pulse current excitation unit, a main control unit, a current regulation execution unit, and a communication interaction unit. The negative temperature coefficient thermistor temperature sensor array is deployed at each sampling point corresponding to the charging gun head, terminals, gun housing, and cable in the current adaptive device, and is electrically connected to the main control unit for real-time acquisition of temperature data and corresponding acquisition timestamps at each sampling node. The differential voltage sampling unit consists of paired differential voltage sampling points and a differential amplification and filtering circuit. The sampling points are electrically connected to the two ends of a preset measured segment in the conductive path of the charging circuit, and are used to acquire the potential signals at both ends of the measured segment, which are then processed by differential arithmetic to obtain the local voltage drop. The current measurement unit uses a Hall current sensor integrated inside the charging gun housing, and is signal-connected to the main control unit for synchronous monitoring of the charging circuit. The system includes a real-time current and current-carrying status monitoring unit, which, in conjunction with the local voltage drop, performs a preliminary estimation of local resistance. A pulse current excitation unit, connected in series in the charging circuit and controlled by the main control unit, applies a controlled current excitation with a preset amplitude and pulse width to the charging circuit. The main control unit, bidirectionally connected to each of the above units, executes the algorithms of the multi-node state sensing module, pulse thermal verification module, current-carrying limit control module, and dynamic current control module, including preliminary estimation of local resistance, temperature compensation correction, thermal response matching verification, and determination of the maximum allowable current-carrying value. A current regulation execution unit, driven by the main control unit and connected in series in the charging circuit, receives commands from the main control unit and performs smooth current limiting, gear switching, and zero-current point disconnection of the charging circuit through phase control and / or periodic on / off control. A communication interaction unit, communicating with the main control unit and interacting with the electric vehicle, charging pile, and backend operation and maintenance platform, issues the maximum allowable current-carrying value and reports and transmits the execution results from the main control unit.

[0011] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0012] This invention effectively solves the technical problems of lagging identification of hidden dangers in local weak parts of cables and lack of online current carrying capacity assessment in existing technologies by the coordinated operation of a multi-node state sensing module, a pulse thermal verification module, a current carrying limit control module and a dynamic current control module. This system utilizes an array of negative temperature coefficient thermistors deployed at weak points in the charging gun and cables. Combined with paired differential voltage sampling and loop current data, it achieves preliminary estimation of the local resistance at each node, avoiding monitoring blind spots. Then, through temperature correction and thermal response verification under short-term controlled current excitation, the resistance value is double-verified and corrected. This allows for accurate identification of potential resistance increases caused by manufacturing defects, poor crimping, etc., before local overheating escalates, overcoming the lag in response of existing technologies. Furthermore, based on the corrected resistance value, the maximum allowable current-carrying value of each node is determined, and the minimum value is taken as the maximum safe current-carrying limit of the loop, enabling online assessment of the minimum cable load-bearing capacity under field conditions. Finally, through phase control or periodic on / off control, smooth current limiting within the safe current-carrying limit is achieved, constructing an automated current regulation system based on detection results. This effectively reduces the risks of insulation aging and fire caused by local overheating, ensuring charging safety and reliability while also considering charging efficiency.

[0013] Specifically, after the charging circuit starts monitoring, the multi-node status sensing module first collects temperature data and corresponding timestamps from multiple sampling nodes, such as the charging gun and weak points in the cable, in real time. Then, through the preset paired differential voltage sampling points of each node, it collects the potential signals at both ends of the measured section in the conductive path of the circuit. After differential amplification and filtering, the local voltage drop is obtained, and the real-time current is collected simultaneously. Subsequently, using the built-in clock reference of the charging gun, the local voltage drop, real-time current, and collection timestamp are time-aligned. Finally, based on the aligned voltage and current data, the preliminary value of the local resistance of each sampling node is determined, and the preliminary estimation is completed. This process uses multiple temperature sensors to accurately cover weak points prone to defects, avoiding monitoring blind spots. The paired differential voltage sampling and time-alignment design ensures the synchronization and accuracy of local voltage drop and current data, effectively improving the accuracy of the preliminary resistance estimation. Overall, it realizes comprehensive and real-time perception of the status of key nodes in the charging circuit, providing reliable data support for subsequent resistance correction and current carrying capacity assessment, and avoiding potential misjudgments or omissions caused by inaccurate data from the source.

[0014] The pulse thermal verification module first calculates the difference between the temperature data of each sampling node and the reference temperature, and couples this with the preset conductor material temperature coefficient to obtain a temperature compensation factor. After coefficient conversion, this factor is coupled with the preliminary local resistance value to generate a correction resistance value, effectively eliminating the interference of temperature changes on resistance measurement. Subsequently, a controlled current excitation with a preset amplitude and pulse width is applied to the charging circuit, and the dynamic change of the current excitation intensity is monitored synchronously. The node temperature change data is collected through a negative temperature coefficient thermistor array, the thermal response curve is recorded, and the steady-state curve segment with compliant current excitation and compliant temperature change rate is selected. The arithmetic mean of its temperature data is calculated as the measured steady-state temperature value. Then, the thermal response steady-state deviation value is obtained by the absolute value of the difference between the thermal response steady-state temperature value and the reference steady-state temperature value. If the thermal response steady-state deviation value is within the corresponding allowable range, the correction resistance value is directly identified as the corrected resistance value; otherwise, the compensation amount is obtained according to the mapping relationship between the corresponding deviation degree and the preset resistance compensation coefficient, and combined with the correction resistance value to form the final corrected resistance value. This dual mechanism of temperature correction and thermal response verification can accurately identify hidden resistance anomalies caused by manufacturing defects, poor crimping, etc. Through dynamic verification and compensation correction, the reliability of resistance data can be further improved, avoiding safety risks caused by misjudgment of resistance.

[0015] The current-carrying limit control module constructs a maximum allowable current-carrying value determination process for two modes of electric vehicle charging: fast charging to slow charging and slow charging to fast charging. This ensures the safety and current-carrying adaptability during mode switching. When switching from fast charging to slow charging, the module first determines the current-carrying status of the circuit based on the correction resistor value. It is considered qualified only if the resistance of each node is within the preset range of the slow charging mode; otherwise, an alarm is issued to avoid the risk of abnormal current carrying capacity from the source. Then, it obtains the initial current-cutting duty cycle. If its fluctuation does not exceed the allowable fluctuation range of the initial current-cutting duty cycle, it is gradually adjusted to the corresponding duty cycle of slow charging according to a predetermined gradient. If its fluctuation exceeds the allowable fluctuation range of the initial current-cutting duty cycle, it first stabilizes the duty cycle by step-wise current reduction and then gradually adjusts the corresponding duty cycle to avoid sudden current surges. Finally, it combines the real-time current-carrying value, the correction resistor value, and the conductor thermal tolerance parameters to calculate the maximum allowable current-carrying value of each node, and takes the minimum value as the maximum safe current-carrying limit of the circuit. The logic of the slow-to-fast charging process remains the same. The core difference lies in adjusting the initial current boost duty cycle. After stabilizing the duty cycle through a stepped current boost, it is gradually adjusted to the duty cycle corresponding to fast charging. Ultimately, the minimum current carrying capacity at each node is taken as the safety limit. This design differentiates the current change characteristics during different mode switching. By pre-determining the current carrying capacity and smoothly adjusting the duty cycle, it solves the problem of local overheating caused by current surges during mode switching. Furthermore, by using the corrected resistance value to calculate the current carrying capacity and combining it with the conductor's thermal tolerance parameters, it achieves precise adaptation to on-site operating conditions, significantly improving the reliability and safety of mode switching and the entire charging process.

[0016] The dynamic current control module offers two current-limiting control methods, achieving precise and stable current regulation within the maximum safe current-carrying limit of the charging circuit, adapting to different equipment and operating conditions. The first method is phase control: based on the real-time temperature and correction resistance value of each sampling node, it dynamically adjusts the current conduction phase angle while simultaneously monitoring node temperature rise. When the temperature rise of a sampling node exceeds the allowable range, the phase angle adjustment magnitude is determined through the temperature-phase angle mapping relationship, delaying the conduction time and simultaneously reducing the equivalent current, achieving a smooth transition from the minimum current limit to the maximum safe current-carrying limit. This method offers precise response, allowing for minute adjustments to the current to cope with slow temperature rises, avoiding localized overheating, and balancing charging efficiency and safety. The second method is periodic on / off control: combining real-time node temperature and conductor thermal tolerance parameters, the maximum safe current carrying capacity is mapped to a fixed current level suitable for discontinuous current limiting equipment according to the current carrying capacity limit-level mapping rule; the on / off duty cycle is adjusted according to the corresponding adjustment gradient to control the conduction time of the charging circuit and achieve near-continuous current output; when the node temperature rise exceeds the corresponding preset range, a prompt is made to switch to the duty cycle level, completing a stable transition from the rated current level to the dynamically adjusted current. The two control methods are complementary and compatible, with phase control meeting the requirements of continuous current limiting and on / off control being compatible with older discontinuous current limiting equipment; through real-time temperature rise monitoring and dynamic adjustment, it can accurately respond to local temperature rise anomalies and achieve smooth current transition, effectively avoiding arcing and damage to the corresponding charging equipment during electric vehicle charging, significantly improving the stability and safety of the electric vehicle charging process. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of a current adaptive control system for electric vehicle charging provided in an embodiment of the present invention;

[0019] Figure 2 This is an internal structural layout diagram of the charging gun and cable provided in an embodiment of the present invention;

[0020] Figure 3 This is a physical assembly flowchart of the current adaptive device provided in an embodiment of the present invention;

[0021] Figure 4 This is a differential voltage sampling circuit diagram provided in an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of a four-wire resistance measurement connection provided in an embodiment of the present invention;

[0023] Figure 6 A diagram showing the human-machine interface of the current adaptive control device provided in an embodiment of the present invention;

[0024] Reference numerals: 1. Terminal block (NTC); 2. Probe end (NTC); 3. Crimping transition (NTC); 4. Cable mid-section (NTC); 5. Internal current sensor in the probe housing; 6 and 7 correspond to the voltage sampling points of the terminal / crimping section, where 6 is the sampling node at one end of the terminal / crimping section and 7 is the sampling node at the other end of the section; 8 and 9 correspond to the voltage sampling points of the cable segment, where 8 is the sampling node at one end of the cable segment and 9 is the sampling node at the other end of the section; 10. Probe head; 11. Terminal; 12. Probe housing; 13. Cable; 14. Voltmeter; 15. Current source; 16. Voltage measurement circuit; 17. Separate current circuit. Detailed Implementation

[0025] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0026] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0027] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0028] Embodiment 1 of the present invention provides a current adaptive control device for electric vehicle charging. This device adopts an integrated structural design, and its integrated carrier is a current adaptive device. The physical assembly process of the current adaptive device will be described in detail below, followed by an explanation of the core components of the control device and the functions of each unit:

[0029] like Figure 3The physical assembly flowchart of the current adaptive device shown below details the specific assembly steps: First, mechanically connect and initially electrically connect the charging head 10 and terminal 11 to ensure precise alignment between the terminals and the conductive areas of the charging head. Second, install the assembled charging head-terminal assembly into the charging housing 12. The housing 12 employs a sealed encapsulation design, which isolates environmental interference such as dust and humidity while reserving a heat dissipation channel to prevent internal core components such as sensors, MCUs, and SCRs from affecting monitoring accuracy due to device self-heating. Third, pass the cable 13 through the reserved channel in the housing and connect it to the terminal via crimping and mechanical snap-fitting. First, the crimping process ensures low resistance characteristics of the electrical connection between conductors, and then the snap-fitting fixes the relative position of the cable and terminal, reducing the risk of increased contact resistance due to poor assembly. Fourth, after assembling all components, seal the seams of the charging housing to form a complete integrated charging gun device, ensuring the mechanical stability and electrical connection reliability of each functional component, providing structural protection for the long-term stable operation of the device.

[0030] The aforementioned current adaptive device, as an integrated structure for current adaptive control of electric vehicle charging, integrates core units that realize the current adaptive control function. Specifically, it includes: a negative temperature coefficient thermistor temperature sensor array, a differential voltage sampling unit, a current measurement unit, a pulse current excitation unit, a main control unit, a current regulation execution unit, and a communication interaction unit. The composition, connection relationship, and function of each unit are as follows:

[0031] A negative temperature coefficient thermistor temperature sensor array is deployed at each sampling point in the current adaptive device, corresponding to the gun head, terminals, gun housing, and cables. Electrically connected to the main control unit, it is used to collect real-time temperature data and corresponding timestamps from each sampling node. A differential voltage sampling unit consists of paired differential voltage sampling points, an operational amplifier, and a filter capacitor. The sampling points are electrically connected to the two ends of a preset test segment in the conductive path of the charging circuit via gold-plated probes. The output of the operational amplifier is connected to the analog-to-digital converter (ADC) pin of the main control unit to collect the potential signal at both ends of the test segment. After differential amplification and filtering, the local voltage drop is obtained. A current measurement unit uses a Hall current sensor integrated inside the charging gun housing, connected to the main control unit, to synchronously monitor the real-time current and current-carrying state of the charging circuit, and to perform a preliminary estimation of the local resistance in conjunction with the local voltage drop. A pulse current excitation unit consists of an insulated-gate bipolar transistor (IGPT). The power switch (SCR), drive circuit, and protection diode are connected in series at the input terminal of the charging circuit. The drive circuit is connected to the PWM output pin of the main control unit to apply a controlled current excitation with a preset amplitude and pulse width to the charging circuit. The main control unit uses an ARM Cortex-M7 architecture MCU chip with built-in ADC, CAN controller, and Flash memory module. It is bidirectionally electrically connected to the above units through analog and digital pins, respectively, to execute algorithms for multi-node state sensing, pulse thermal verification, current limit control, and dynamic current control, and to complete preliminary estimation of local resistance, temperature compensation correction, thermal response matching verification, and determination of the maximum allowable current value. The current regulation execution unit consists of a silicon controlled rectifier (SCR). The SCR module, along with the filter inductor and capacitor, is connected in series in the main path of the charging circuit. The control terminal of the SCR module is connected to the drive pin of the main control unit to receive commands from the main control unit. It achieves smooth current adjustment through phase control or achieves near-continuous current output through periodic on / off control, completing current limiting, gear switching, and zero-current-point disconnection operations. The communication interaction unit consists of a CAN bus and 5G wireless communication. It is connected to the communication pin of the main control unit and can interact with electric vehicles and charging piles through the CAN bus and the 5G network to send the maximum allowable current carrying value, report the device's operating status, and transmit the execution results of the main control unit.

[0032] Based on the aforementioned current adaptive control device, a current adaptive control system for electric vehicle charging is provided. This system precisely matches the dynamic current-carrying capacity of key components in the electric vehicle charging circuit, achieving safe current limiting and reliable protection during the charging process. It avoids safety hazards such as overheating and arcing caused by localized current overload, balancing charging safety and efficiency. Figure 1 The diagram shows a structural schematic of a current adaptive control system for electric vehicle charging. This system may include the following execution modules:

[0033] Multi-node state sensing module: First, a negative temperature coefficient (NTC) thermistor (NTC) temperature sensor array is used to achieve parallel acquisition of temperature data corresponding to each sampling node in the electric vehicle charging link. This array is typically composed of NTC temperature sensors with consistent performance, distributed according to a unified signal acquisition circuit. It strictly targets weak points in the charging cable or connectors during the electric vehicle charging process. These points are prone to local wear, loosening of crimps, and reduction of cross-sectional area due to structural characteristics, usage frequency, or stress conditions, leading to increased contact resistance and localized overheating. Specific deployment locations are as follows... Figure 2 The diagram shows the internal structure layout of the charging gun and cables:

[0034] The NTC1 at the charging head, NTC2 at the terminal, NTC4 at the crimping point, and NTC5 at the middle section of the cable are respectively used for temperature monitoring of the aforementioned vulnerable areas. Specifically, the terminal NTC1 is deployed on the outside of the crimping cup at the connection between the cable and the terminal to detect loosening of the crimp caused by crimping process deviations, long-term thermal cycling, or vibration, and to identify the resulting local resistance anomalies. The NTC2 at the charging head is deployed in the core conductive area inside the charging gun head, avoiding the insertion and removal stress points during installation, to monitor terminal wear and oxidation caused by frequent insertion and removal, and to promptly detect the risk of local overheating. The NTC3 at the crimping transition point is deployed on the surface of the cable crimping sleeve to monitor the temperature of this area due to long-term cable tension. Tensile stress and current thermal effects can cause issues such as loosening of the crimped layer and conductor breakage, providing early warning of the risk of insufficient local current-carrying cross-sectional area. The NTC4 in the middle section of the cable is deployed in the geometric center area of ​​the middle section to cover the risk of insulation layer damage and conductor wear caused by bending, dragging, and squeezing in this concealed part, and to detect overheating caused by local reduction in cross-sectional area in a timely manner. The current sensor 5 inside the charging gun housing is deployed inside the charging gun housing near the cable inlet end to collect the working current data of the charging circuit in real time. This provides core electrical parameter support for subsequent calculation of local resistance and evaluation of current-carrying capacity based on voltage drop. It is fixed in the pre-set mounting groove of the gun housing and is attached to the inner wall of the gun housing through an insulating thermally conductive pad, taking into account both electrical isolation and heat dissipation requirements.

[0035] Points 6 and 7: These correspond to voltage sampling points on the terminals / crimped sections. Point 6 is a sampling node at one end of the terminal / crimped section, and point 7 is a sampling node at the other end. Together, they are used to collect the local voltage drop of the terminal / crimped section. Points 8 and 9: These correspond to voltage sampling points on the cable segments. Point 8 is a sampling node at one end of the cable segment, and point 9 is a sampling node at the other end. These are used to collect the local voltage drop of the cable segment. To ensure the accuracy and response speed of the temperature data, all the above NTC sensors adopt a standardized fixing process: they are tightly bonded to the conductor / metal shell surface with high-temperature resistant epoxy resin adhesive, and the bonding surface is evenly coated with high-thermal-conductivity silicone grease to fill the gaps and improve heat conduction efficiency. The NTC sensor leads use high-temperature resistant shielded wires to avoid electromagnetic interference during charging affecting signal stability.

[0036] Secondly, this module uses a combination strategy of differential voltage sampling and four-wire resistance measurement to achieve a preliminary estimation of the local resistance of each sampling node. The corresponding hardware circuit design and function are as follows:

[0037] like Figure 4 The differential voltage sampling circuit diagram shown is a differential voltage amplification circuit composed of operational amplifiers. Its core components include operational amplifiers, resistors, capacitors, and a voltage boosting unit. Its principle is to amplify, filter (using capacitors), and boost the differential voltage across the sampling resistor at a preset test section (such as a cable crimp or terminal connection) in the conductive path of the charging circuit, before outputting it to the MCU's ADC pin to complete voltage acquisition. The key function of this circuit is to eliminate common-mode interference in the charging environment, improve the acquisition accuracy of small voltage signals, and provide stable and reliable voltage data support for local resistance estimation. Figure 4 In this diagram, 'a' is the device identifier for the operational amplifier (chip), representing the core operational amplifier component in the circuit; 'b' is the non-inverting input (+ input) of the operational amplifier, used to input one of the differential voltage signals (in conjunction with the 1.25V reference voltage of the voltage boosting unit); 'c' is the inverting input (- input) of the operational amplifier, used to input the other differential voltage signal; and 'd' is the output of the operational amplifier, used to output the amplified, filtered, and voltage-boosted voltage signal, which is then transmitted to the ADC pin. These pins are the core interfaces for the operational amplifier to achieve differential amplification, working together to accurately process small voltage signals.

[0038] like Figure 5The diagram shows a four-wire resistance measurement connection. The leftmost end is the preset test section of the charging link. The right end uses a four-wire connection between current source 15 and voltmeter 14 to achieve local resistance measurement: current source 15 injects a constant current into the preset test section, and voltmeter 14 simultaneously collects the local voltage drop across the preset test section. The local resistance is calculated using Ohm's law R=U / I. The core advantage of this scheme is that by separating the current loop 17 and the voltage measurement loop 16, the influence of lead resistance on the measurement results is eliminated, ensuring the accuracy of the preliminary estimation of local resistance from a hardware perspective.

[0039] To further eliminate the interference of asynchronous data errors on local resistance estimation, a timing alignment mechanism is introduced: A pre-set clock reference integrated within the electric vehicle charging gun is used to uniformly calibrate the local voltage drop output by the differential voltage sampling circuit, the real-time current acquired by the four-wire measurement circuit, and the acquisition timestamp recorded by the NTC temperature sensor array. This mechanism ensures that voltage, current, and temperature data at the same sampling moment correspond one-to-one, avoiding parameter mismatches caused by signal transmission delays. This improves the accuracy of the initial local resistance estimation from a data perspective, providing reliable data support for subsequent module resistance correction and current-carrying capacity assessment.

[0040] Pulse thermal verification module: First, acquire the real-time temperature data T of each sampling node. i (i=1,2,3,…,n, where n is the number of sampling nodes) and a preset reference temperature T0 (usually 25℃, i.e., standard ambient temperature), calculate the temperature deviation between the two. Combined with the temperature coefficient of the conductor material corresponding to each sampling node (Determined by the properties of the conductor material, such as the temperature coefficient of copper being approximately 0.00393 / ℃), the temperature compensation factor KT is obtained through coupling calculations. i The calculation formula is: This temperature compensation factor is used to eliminate the influence of temperature changes on resistance measurement. The obtained temperature compensation factor is then inversely proportionalized (this inverse proportionalization is based on the positive correlation between temperature and resistance; the reciprocal of the compensation factor is used to correct the resistance at the real-time temperature to the state at the reference temperature), and then compared with the local resistance R output by the multi-node state sensing module. est,i Perform coupling operations to obtain the correction resistance value R of each sampling node. coor,i The calculation formula is: R coor,i =R est,i ×KT i This corrects resistance measurement deviations caused by temperature deviations from the reference value, conforming to the physical law of conductor resistance changing with temperature, ensuring that the corrected resistance value accurately reflects the actual resistance state of the sampling node. Subsequently, a controlled current excitation with preset parameters is applied to the charging circuit by the pulse current excitation unit, wherein the excitation current amplitude I... pulseThe pulse duration is 3-8A (adjustable according to the safety boundary of the charging circuit), and the pulse duration is t. pulse The time is 3 to 8 seconds, and the dynamic changes of the current excitation intensity are monitored within the preset time window to ensure that the excitation parameters are stable and meet the preset requirements.

[0041] Secondly, the temperature change data ΔT of each sampling node during the entire controlled current excitation process is collected in real time using an NTC temperature sensor array. real,i (t) (t is a time variable), synchronously record the thermal response curve L of the temperature change data of each node as a function of the current excitation intensity. i The horizontal axis of the curve represents the current excitation intensity, and the vertical axis represents the temperature change. For each thermal response curve L... i Segmented screening is performed, selecting those with current excitation intensity not exceeding the preset current excitation intensity I. lim (Typically 95% of the excitation amplitude; the preset value can be fine-tuned by the operator based on the characteristics of the charging circuit conductor material, the thermal response sensitivity of the sampling node, and the ambient temperature.) And the temperature change rate... <ΔT rate,lim (The curve segment with a preset temperature change rate, such as 0.2℃ / s, is determined to be the steady-state curve segment L based on the thermal equilibrium characteristics of the conductor. When the temperature change rate is lower than this value, it can be determined that the node temperature tends to stabilize, avoiding deviations in measured data due to the temperature not reaching a steady state.) i,steady Calculate the arithmetic mean of all temperature change data within the steady-state curve segment, and use it as the measured steady-state temperature value ΔT at each sampling node. meas,i .

[0042] Finally, the reference steady-state temperature value ΔT corresponding to each sampling node is obtained. ref,i (i.e., the resistance value is R) coor,i The theoretical temperature rise at time (the actual temperature rise) is used to calculate the absolute value of the difference between the measured steady-state temperature value and the reference steady-state temperature value, thus obtaining the thermal response steady-state deviation value. A preset allowable range for the thermal response steady-state deviation is set, such as 0 to 2℃. The result obtained by summing and averaging the maximum values ​​of the historical thermal response steady-state deviations during the analysis of historical measured temperature data is used as the upper limit of the preset allowable range for the thermal response steady-state deviation, i.e., 2℃. If the thermal response steady-state deviation value of a certain sampling node is within this range, the correction resistor value R is determined. coor,i It can accurately adapt to the thermal response state corresponding to the charging circuit and directly use it as the correction resistance value R of that node. final,i If the steady-state deviation of the thermal response of a certain sampling node is not within the range, the preset mapping table of steady-state deviation of thermal response and resistance compensation coefficient is queried (established through experimental calibration, the deviation value and the compensation coefficient are positively correlated, the input is the steady-state deviation of the thermal response of the current sampling node, and the output is the resistance compensation coefficient that matches the deviation value), the resistance compensation amount of the node is obtained, and it is added to the correction resistance value to obtain the final correction resistance value.

[0043] Current carrying limit control module: Determined by the main control unit receiving trigger signals through the communication interaction unit: When the electric vehicle or charging pile issues a fast / slow charging mode switching command (such as user operation of charging pile buttons, or mode switching signal issued by the electric vehicle battery management system), the communication interaction unit transmits the command to the main control unit. The main control unit determines the current charging mode and the target mode, triggering the maximum allowable current carrying value determination process for the corresponding scenario.

[0044] Scenario 1: Determining the maximum allowable current carrying capacity when switching from fast charging mode to slow charging mode:

[0045] The main control unit calls the corrected resistance values ​​of each sampling node output by the pulse thermal verification module, and simultaneously retrieves the preset slow charging mode current-carrying resistance range (this range is pre-calibrated by conductor material, charging power level, and safety standards). It checks whether the corrected resistance value of each sampling node is within this range. If the corrected resistance values ​​of all sampling nodes are within this range, the current-carrying state of the current charging circuit is deemed qualified, allowing entry into the subsequent current adjustment process. If the corrected resistance value of any sampling node exceeds this range, the current-carrying state is deemed abnormal. The main control unit triggers an alarm through the communication interaction unit (such as a local buzzer alarm or a background abnormality notification) and suspends the mode switching process. After the current-carrying state is deemed qualified, the following current protection control process is executed:

[0046] (1) The main control unit obtains the initial duty cycle of the charging circuit in the current fast charging mode (the duty cycle refers to the ratio of the current turn-off time to the total cycle time within a unit cycle), and retrieves the preset duty cycle transition range and the allowable fluctuation range of the duty cycle at the same time; (2) Calculate the fluctuation range of the initial duty cycle in the duty cycle transition range. If the fluctuation range does not exceed the allowable range, adjust the gradient according to the preset duty cycle, such as adjusting by 0.05 each time with an adjustment interval of 1 second. The basis for setting this is: combining the stability requirement of current adjustment and the balance of charging efficiency in the slow charging mode, adjusting the gradient by 0.05 each time can avoid the circuit impact caused by the current change being too fast, and the adjustment interval of 1 second can ensure that the main control unit can monitor the circuit status after the current adjustment in a timely manner and ensure the stability of the adjustment process. (3) If the fluctuation range of the initial interruption duty cycle exceeds the allowable range, the corresponding current adjustment gradient is determined according to the degree of deviation of the duty cycle. The greater the deviation, the smaller the adjustment gradient. For example, when the deviation exceeds 20%, the gradient is 0.02. The equivalent current of the charging circuit is reduced stepwise. The 0.02 is determined based on the principle of prioritizing circuit safety and stability. Its value is the result of historical equivalent current adjustment experiment. After each reduction of the current, the fluctuation range of the initial interruption duty cycle is re-detected until the fluctuation range meets the allowable range. Then, it is gradually adjusted to the target interruption duty cycle of the slow charging mode according to the preset adjustment gradient to avoid the impact of sudden current change on the circuit.

[0047] After the initial current interruption duty cycle is adjusted to the target value of slow charging mode, the current measurement unit collects the current real-time current carrying value of the charging circuit in real time. The main control unit combines the correction resistance value of each sampling node and the thermal tolerance parameters of the charging circuit conductor (such as the maximum allowable temperature of the conductor, heat dissipation coefficient, etc.) to calculate the maximum allowable current carrying value of each sampling node (the calculation logic is based on the conductor's heat dissipation capacity and the resistance heating characteristics to ensure that the conductor temperature does not exceed the maximum allowable value when carrying current). The minimum value among the maximum allowable current carrying values ​​of all sampling nodes is taken as the maximum safe current carrying limit of the charging circuit in the scenario of switching from fast charging mode to slow charging mode.

[0048] Scenario 2: Determining the maximum allowable current carrying capacity when switching from slow charging mode to fast charging mode:

[0049] The current-carrying status determination logic is consistent with that of the fast-charging to slow-charging scenario: the main control unit retrieves the correction resistor values ​​of each sampling node and the preset fast-charging mode current-carrying resistance range (pre-calibrated by conductor material, fast-charging power level, and safety standards). If the correction resistor values ​​of all sampling nodes are within this range, the current-carrying status is deemed qualified; otherwise, an anomaly is determined and an alarm is triggered, pausing mode switching. After the current-carrying status is deemed qualified, the following current protection control process is executed:

[0050] (1) The main control unit obtains the initial boost duty cycle in the current slow charging mode (the boost duty cycle refers to the ratio of the current conduction time in a unit cycle to the total cycle time), and retrieves the preset duty cycle transition range and the allowable fluctuation range of the duty cycle; (2) Calculate the fluctuation amplitude of the initial boost duty cycle. If the fluctuation amplitude does not exceed the allowable fluctuation range of the initial boost duty cycle, the gradient is adjusted according to the preset boost duty cycle, such as adjusting by 0.03 each time with an adjustment interval of 0.8 seconds. This is a setting that balances the fast charging switching efficiency and safety stability: the gradient of 0.03 can steadily approach the fast charging target duty cycle and avoid excessive switching time, and can also control the current rise rate to prevent sudden overheating. The 8-second interval allows the main control unit to monitor the circuit status after adjustment in a timely manner, taking into account both efficiency and risk control; the initial boost duty cycle is gradually adjusted to the target boost duty cycle corresponding to the fast charging mode (pre-calibrated by the fast charging power requirement); (3) if the fluctuation range of the initial boost duty cycle exceeds the allowable range, the corresponding current adjustment gradient is determined according to the degree of deviation of the duty cycle (the greater the deviation, the smaller the adjustment gradient), and the equivalent current of the charging circuit is increased in a stepwise manner; after each current increase, the fluctuation range is re-detected until the fluctuation range meets the allowable range, and then it is gradually adjusted to the target boost duty cycle of the fast charging mode according to the preset adjustment gradient to avoid sudden current changes leading to local overheating.

[0051] After the initial boost duty cycle is adjusted to the target value of fast charging mode, the current measurement unit collects the current real-time current value; the main control unit combines the corrected resistance value and conductor thermal tolerance parameters of each sampling node, and calculates the maximum allowable current value of each sampling node through the same calculation steps as the fast charging to slow charging scenario; the minimum value among the maximum allowable current values ​​of all sampling nodes is taken as the maximum safe current limit of the charging circuit in the scenario of switching from slow charging mode to fast charging mode.

[0052] The dynamic current control module addresses different operating conditions during electric vehicle charging by employing two differentiated strategies: phase control and periodic on / off control. This ensures precise and stable current regulation within the maximum safe current-carrying limit of the charging circuit, guaranteeing charging safety and efficiency. The specific execution steps and scenario adaptation logic are as follows:

[0053] For scenarios requiring precise and smooth current adjustment to adapt to dynamic current carrying demands, a phase control strategy is adopted. This strategy is suitable for electric vehicle charging piles that support continuous current limiting communication (such as receiving dynamic current commands via CAN bus), scenarios where the temperature of a certain node rises slowly during charging and requires a slight reduction in current to avoid derating, or scenarios where the charging power demand fluctuates smoothly (such as home slow charging) and requires stable current output to reduce battery charging fluctuations. The execution steps are as follows:

[0054] Within the maximum safe current carrying limit of the charging circuit, the main control unit calls the real-time temperature data of each sampling node collected by the NTC temperature sensor array and the correction resistance values ​​of each node output by the pulse thermal verification module. Based on the above real-time temperature and correction resistance values, the main control unit calls the preset phase angle-current mapping algorithm: taking the AC voltage zero crossing point as a reference, the conduction phase angle is changed by delaying the start time of current conduction. The smaller the phase angle, the longer the current conduction time and the larger the equivalent current. The larger the phase angle, the shorter the conduction time and the smaller the equivalent current. The degree of delay in the start time of current conduction is determined based on the current carrying redundancy of the current node calculated by the real-time temperature and correction resistance values. The smaller the current carrying redundancy, the greater the delay, ensuring that the reduction of the equivalent current matches the current carrying capacity. At the same time, the temperature rise of each sampling node is continuously monitored, and the temperature rise rate per unit time is calculated. If the temperature rise of a certain sampling node exceeds the preset allowable temperature rise, the main control unit inputs the excess temperature rise deviation (the difference between the measured temperature rise and the allowable temperature rise) into the preset temperature-phase angle mapping relationship (this mapping relationship is established through experimental calibration to clarify the phase angle fine-tuning amount corresponding to different temperature rise deviations). Based on the mapping result, the corresponding current conduction phase angle fine-tuning amplitude is obtained. By delaying the current conduction time, the equivalent current of the preset amplitude (usually 0.1~0.3A, set based on the charging power level and battery tolerance) is simultaneously reduced. The entire adjustment process is gradually advanced according to the preset gradient, realizing a smooth transition from the minimum current limit of the charging circuit to the maximum safe current carrying limit. This avoids the impact of sudden current changes on the battery and charging circuit, and can respond to slow temperature rise issues in a timely manner. While ensuring charging safety, it maximizes charging efficiency, which meets the needs of scenarios with high requirements for current stability, such as home slow charging.

[0055] For scenarios requiring rapid response to operating conditions and compatibility with non-continuous current-limiting devices, a periodic on / off control strategy is adopted. This strategy is suitable for electric vehicles / charging piles that do not support continuous current limiting (only support fixed-level current input), where the maximum safe current carrying capacity limit needs to be mapped to a fixed level and then the current needs to be stabilized by on / off control, or for short-duration fast charging scenarios (where current demand is high and rapid response to sudden temperature changes at nodes is required). The execution steps are as follows:

[0056] Within the maximum safe current carrying capacity of the charging circuit, the main control unit combines the real-time temperature of each sampling node and the thermal tolerance parameters of the charging circuit conductors, such as the maximum allowable temperature of the conductor, which is obtained from a conductor material specification lookup library. Different conductor materials correspond to a maximum allowable temperature standard value. Simultaneously, personnel can fine-tune the parameters based on the ambient temperature. Following a preset current carrying capacity limit-level mapping rule (established through experimental calibration to define the fixed current level corresponding to different maximum safe current carrying capacities), the maximum safe current carrying capacity of the current scenario is mapped to an acceptable fixed current level for the charging circuit under discontinuous current limiting conditions. The main control unit retrieves the duty cycle adjustment gradient matching the aforementioned fixed current level and adjusts the current on / off duty cycle (i.e., the ratio of the on-time to off-time of the current within the control unit monitoring cycle) through the current adjustment execution unit. Simultaneously, a filter circuit suppresses harmonic interference generated by current switching, achieving near-continuous current output and ensuring charging stability. During the above control process, the temperature rise of each sampling node is continuously monitored. If the temperature rise of any sampling node exceeds the preset allowable temperature rise, the main control unit immediately sends a prompt signal through the communication interaction unit, triggering the switching from the current fixed current level to the duty cycle level (switching to a flexible control mode with dynamically adjustable duty cycle). This can quickly adapt to changes in current demand and temperature changes in fast charging scenarios. At the same time, it is compatible with older devices that do not support continuous adjustment. By adjusting the duty cycle and cooperating with the filtering circuit, it achieves near-continuous current output under the hardware limitation of discontinuous current limiting, taking into account device compatibility, response speed and charging stability, and meeting the operating conditions of fast charging and older charging devices.

[0057] This invention, in its first embodiment, achieves precise adaptive control of electric vehicle charging current through multi-unit collaboration and multi-module linkage design, significantly improving charging safety, stability, and equipment compatibility. Its core advantages are threefold: First, precise and comprehensive multi-node state perception. By locking weak points in the link through an NTC array, combined with differential voltage sampling and four-wire resistance measurement, and a timing alignment mechanism, interference and asynchronous data errors are effectively eliminated, providing reliable data support for subsequent control. Second, scientifically rigorous resistance correction and current-carrying limit control. The pulse thermal verification module achieves precise resistance correction through temperature compensation and thermal response verification. The current-carrying limit control module, for mode switching scenarios, avoids sudden current surges and ensures safe mode switching through smooth duty cycle adjustment and safe current calculation. Third, highly adaptable dynamic control strategies. Phase control and periodic on / off control switch as needed, meeting the smooth adjustment requirements of continuous current-limiting scenarios while also being compatible with older non-continuous current-limiting equipment and the rapid response requirements of fast charging. The overall solution effectively avoids potential hazards such as localized overheating and arcing, balancing charging efficiency and safety, and adapting to diverse charging conditions.

[0058] Based on the basic architecture of Embodiment 1, and to address the complex operating conditions requiring simultaneous switching between slow and fast charging modes and the coexistence of phase control and periodic on / off control, supplementary embodiments, namely Embodiment 2 and Embodiment 3, are added, with the specific designs as follows:

[0059] Example 2: Determination process of maximum allowable current carrying capacity when slow charging and fast charging modes coexist.

[0060] This embodiment is applicable to scenarios where frequent switching between slow charging and fast charging modes is required during charging (such as when users flexibly adjust charging power based on remaining battery power, or when charging piles dynamically match grid load switching modes). The core principle is to achieve consistent and efficient determination of the maximum allowable current carrying capacity under the condition of coexisting mode switching, avoiding current fluctuations and safety risks during mode switching intervals. The specific process is as follows:

[0061] The main control unit receives mode switching commands from the electric vehicle battery management system or charging pile in real time through the communication interaction unit. At the same time, it retrieves historical operating data from the current carrying limit control module and establishes a priority judgment mechanism for switching commands and current carrying status: if the current state is fast charging, the current reduction pre-adjustment should be performed first after the slow charging switching command is triggered; if the current state is slow charging, the current carrying redundancy of the circuit should be checked first after the fast charging switching command is triggered to ensure that the switching command matches the current operating condition.

[0062] By integrating the current-carrying resistance ranges of the slow charging and fast charging modes in Implementation Example 1, a global current-carrying resistance reference range is established. This range covers the intersection and transition range of the current-carrying resistance ranges of the slow charging mode and the fast charging mode. When switching modes, the main control unit calls each sampling node to correct the resistance value, first checking whether it is within the global current-carrying resistance reference range. If it is within the global current-carrying resistance reference range, the duty cycle adjustment process of the corresponding mode is directly entered, without repeating the complete current-carrying state determination, thus shortening the switching response time. If it exceeds the global current-carrying resistance reference range, an abnormal alarm is triggered and pre-stabilization adjustment is performed (such as slightly reducing the current when switching from fast charging to slow charging, and slightly increasing the current when switching from slow charging to fast charging), until the resistance value falls into the global current-carrying resistance reference range.

[0063] A transitional current-carrying buffer is added between the slow-charging to fast-charging and fast-charging to slow-charging processes. The maximum allowable current-carrying value in this interval is the midpoint between the maximum safe current-carrying limits of the two modes. During mode switching, the current is first adjusted to the transitional current-carrying buffer, and then the duty cycle adjustment and current-carrying limit calculation of the target mode are performed. At the same time, the correction resistance value and temperature data of each sampling node are updated synchronously to ensure that the current-carrying limit calculation is consistent before and after mode switching, and to avoid misjudgment of current-carrying due to data lag.

[0064] The main control unit integrates the calculation results of the maximum allowable current carrying capacity of the two modes in real time. When the fast charging to slow charging mode is triggered, the maximum safe current carrying capacity limit calculated in the slow charging mode is used as the core, and the current carrying capacity redundancy correction of the fast charging mode is added. When the slow charging to fast charging mode is triggered, the maximum safe current carrying capacity limit calculated in the fast charging mode is used as the core, and the steady-state temperature data of the slow charging mode is referenced for calibration to ensure that the maximum allowable current carrying capacity in the coexisting scenario always adapts to the current mode and loop state.

[0065] Example 3: Current limiting control process with phase control and periodic on / off control coexisting.

[0066] This embodiment is applicable to complex operating conditions such as sudden changes in node state during charging, mixed charging environments, and high-power charging. The core is to achieve adaptive switching and coordinated operation of two control modes, taking into account adjustment accuracy, response speed, and equipment compatibility. The specific control logic is as follows:

[0067] The main control unit presets the working condition-control mode mapping rules and triggers switching based on real-time monitoring data: For example, if the temperature at the crimping point rises suddenly (≥5℃ / second): periodic on / off control is immediately triggered, and the equivalent current is quickly reduced by rapidly adjusting the on / off duty cycle (adjusting the gradient to 0.01) to suppress the continuous temperature rise; after the temperature change rate is ≤0.2℃ / second (tending to stabilize), it automatically switches to phase control, and achieves precise current fine-tuning through fine phase angle adjustment to maintain stable charging.

[0068] In mixed charging environments (such as public charging stations for multiple vehicle brands): the main control unit reads the vehicle charging control capability parameters (such as whether continuous current limiting is supported) through the communication interaction unit. If the vehicle supports continuous current limiting, phase control is enabled; if it only supports fixed current levels, periodic on / off control is enabled.

[0069] Dual control mode coordinated regulation mechanism: An additional control strategy coordination unit is added to realize parameter sharing and coordination between the two control modes: the phase angle adjustment data of phase control and the duty cycle adjustment data of periodic on / off control are synchronized in real time to the shared storage module of the main control unit, providing a consistent parameter basis for switching between the two control modes; under both control modes, the monitoring data of NTC temperature sensor array and current measurement unit are shared, and when either control mode triggers an abnormality, the emergency adjustment of the other control mode can be triggered simultaneously, forming dual safety protection.

[0070] The supplementary embodiments two and three further expand the device's adaptability to different operating conditions based on embodiment one: Embodiment two solves the problems of response lag and current fluctuation when modes switch simultaneously by sharing a verification benchmark and adding a transition buffer, thereby improving the continuity and safety of mode switching; Embodiment three achieves complementary advantages of the two control methods through an adaptive switching trigger mechanism and a collaborative control unit, which not only ensures the adjustment accuracy and response speed under complex operating conditions, but also improves the device compatibility and reliability of high-power charging scenarios, making the overall system more adaptable to the diverse and complex needs in the actual charging process.

[0071] It should be added that, such as Figure 6 The diagram shows the human-machine interface of the current adaptive device. At this point, the current adaptive device measures the maximum allowable current carrying capacity of 16A at the thinnest part of the cable and automatically adjusts the output current to 16A for charging. The top 00:00:00 is the charging timer, displaying the current charging duration. The upper left 225.5V is the real-time charging voltage. The lower left 0.00kW is the real-time charging power. The lower right 0.000kWh is the cumulative charging amount. The bottom 28℃ is the operating ambient temperature of the current adaptive device, and 9.0V is the auxiliary power supply voltage of the current adaptive device. The labels on the side indicate the charging connection status, power supply status, and grounding status, respectively, intuitively presenting the device's operating parameters and status.

[0072] In summary, attached Figure 3 Foundation: Provides the physical structural framework of the device, ensuring precise positioning of each component; Appendix Figure 2 For core monitoring: determine the installation locations of sensors / actuators to achieve blind-spot-free monitoring; (Attached) Figure 4 With appendix Figure 5 For the data acquisition layer: It acquires raw data of resistance, voltage, and current through a high-precision measurement scheme; (Attached) Figure 6 For the output layer: visualize and interact with the data processing results and device status, forming a complete closed loop of structure, monitoring, acquisition, and feedback.

[0073] The above embodiments can be implemented, in whole or in part, by software, hardware (such as circuits), firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the flow or function according to the embodiments of the present invention is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. Computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. A computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. Available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media. Semiconductor media can be solid-state drives.

[0074] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0075] In various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0076] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0077] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A current adaptive control system for charging electric vehicles, characterized in that, The system includes: The multi-node state sensing module is used to collect temperature data of multiple sampling nodes in real time through a negative temperature coefficient thermistor temperature sensor array deployed on the electric vehicle charging gun and / or charging cable, and to preliminarily estimate the local resistance of each sampling node based on the local voltage drop data collected by the corresponding preset differential voltage sampling point of each sampling node and the current data of the charging circuit. The differential voltage sampling points are arranged in pairs and electrically connected to the two ends of a preset test segment in the conductive path of the charging circuit, so as to obtain the local voltage drop of the preset test segment. The sampling node is a pre-defined weak point in the conductive path of the charging gun connector and / or the charging cable. The pulse thermal verification module is used to perform temperature correction on the local resistance based on the temperature data to obtain the correction resistance value. After applying a controlled current excitation for a predetermined time window in the charging circuit, the module verifies and corrects the correction resistance value based on the temperature response of each sampling node to obtain the correction resistance value of each sampling node. The current carrying limit control module is used to determine the maximum allowable current carrying value of each sampling node based on the correction resistance value of each sampling node, and take the minimum value of the maximum allowable current carrying value of all sampling nodes as the maximum safe current carrying limit of the corresponding charging circuit during the charging process of electric vehicle; A dynamic current control module is used to perform current limiting control on the charging circuit within the maximum safe current carrying limit, wherein the current limiting control includes at least one of phase control and / or periodic on / off control. The pulse thermal verification module includes: The temperature data of each sampling node and the corresponding reference temperature are calculated to obtain the temperature compensation factor by coupling the temperature data with the conductor material temperature coefficient preset for each sampling node. The obtained temperature compensation factor is converted into coefficients and then coupled with the preliminary value of local resistance to obtain the correction resistance value of each sampling node. After applying a controlled current excitation with a preset amplitude and pulse width to the charging circuit, monitor the dynamic change of the corresponding current excitation intensity within a preset time window, and simultaneously verify the matching degree between the correction resistor value and the current excitation intensity. The verification of the matching degree between the correction resistor value and the current excitation intensity is specifically as follows: The temperature change data of each sampling node during the controlled current excitation process is collected by a negative temperature coefficient thermistor temperature sensor array, and the thermal response curve of the temperature change data as a function of the current excitation intensity is recorded. The segment of the thermal response curve where the current excitation intensity does not exceed the preset current excitation intensity and the temperature change rate is less than the preset temperature change rate is recorded as the steady-state curve segment. The arithmetic mean of the temperature change data corresponding to each sampling node in the steady-state curve segment is calculated and used as the measured steady-state temperature value. The absolute value of the difference between the measured steady-state temperature value and the reference steady-state temperature value is recorded as the thermal response steady-state deviation value. If the thermal response steady-state deviation value is within the preset allowable range of thermal response steady-state deviation, then the correction resistor value is determined to be the correction resistor value corresponding to the thermal response state of the final adapted charging circuit. Conversely, based on the mapping relationship between the deviation of the steady-state deviation value of the thermal response and the preset resistance compensation coefficient, the resistance compensation amount is obtained, and the sum of the resistance compensation amount and the correction resistance value is used as the correction resistance value for the corresponding thermal response state of the final adapted charging circuit.

2. The current adaptive control system for electric vehicle charging as described in claim 1, characterized in that, The multi-node state awareness module includes: During the charging circuit startup monitoring state, temperature data from multiple sampling nodes and the corresponding collection timestamps for each sampling node are acquired. By using the preset paired differential voltage sampling points of each sampling node, the potential signals of the nodes at both ends of the preset test section in the corresponding conductive path of the charging circuit are collected. The local voltage drop of each preset test section is obtained through differential operation processing, and the real-time current of the charging circuit is collected simultaneously. The local voltage drop, the real-time current, and the acquisition timestamp are time-aligned by a pre-set clock reference integrated inside the electric vehicle charging gun. Based on the local voltage drop and real-time current after timing alignment, the preliminary value of the local resistance of each sampling node is determined, and the preliminary estimation of the local resistance of each sampling node is completed.

3. The current adaptive control system for electric vehicle charging as described in claim 1, characterized in that, The current-carrying limit control module includes: The process for determining the maximum allowable current carrying capacity in the scenario of switching from fast charging mode to slow charging mode during electric vehicle charging, and / or the process for determining the maximum allowable current carrying capacity in the scenario of switching from slow charging mode to fast charging mode during electric vehicle charging.

4. The current adaptive control system for electric vehicle charging as described in claim 3, characterized in that, When switching from fast charging mode to slow charging mode during the charging process of an electric vehicle, the process for determining the maximum allowable current carrying capacity specifically includes: The current-carrying state of the current charging circuit is determined based on the obtained correction resistance value, specifically as follows: If the correction resistance value of each sampling node is within the preset current-carrying resistance range of the slow charging mode, the current-carrying state of the current charging circuit is determined to be qualified; otherwise, the current-carrying state is determined to be abnormal, and an alarm prompt for abnormal current-carrying state is issued. Based on the charging circuit that has passed the current-carrying state determination, the current protection control process is executed, specifically as follows: If the initial current cutoff duty cycle in the current fast charging mode is obtained, and the fluctuation range of the initial current cutoff duty cycle within the preset duty cycle transition range does not exceed the allowable fluctuation range of the initial current cutoff duty cycle, then the initial current cutoff duty cycle is gradually adjusted to the duty cycle of the corresponding current carrying state in the slow charging mode according to the preset current cutoff duty cycle adjustment gradient. Conversely, based on the adjustment gradient corresponding to the degree of duty cycle deviation exceeding the preset allowable fluctuation range, the equivalent current of the charging circuit is reduced in stages until the fluctuation amplitude of the initial current interruption duty cycle within the preset duty cycle transition range does not exceed the preset allowable fluctuation range. Then, the initial current interruption duty cycle is gradually adjusted to the duty cycle of the corresponding current carrying state in slow charging mode according to the preset current interruption duty cycle adjustment gradient. After the initial current interruption duty cycle is gradually adjusted, the real-time current carrying value of the charging circuit under the current current carrying state is monitored and collected. Based on the real-time current carrying value, combined with the correction resistance value of each sampling node and the conductor thermal tolerance parameter of the corresponding charging circuit, the maximum allowable current carrying value of each sampling node is calculated, and the minimum value of the maximum allowable current carrying value of all sampling nodes is taken as the maximum safe current carrying limit of the charging circuit in the corresponding scenario of switching from fast charging mode to slow charging mode.

5. The current adaptive control system for electric vehicle charging as described in claim 3, characterized in that, When switching from slow charging mode to fast charging mode during the charging process of an electric vehicle, the process for determining the maximum allowable current carrying capacity is as follows: In the charging circuit after the current carrying state is qualified, the initial current boost duty cycle in the current slow charging mode is obtained, and the fluctuation range of the initial current boost duty cycle in the preset duty cycle transition range does not exceed the allowable fluctuation range of the initial current boost duty cycle. Then, according to the preset current boost duty cycle adjustment gradient, the initial current boost duty cycle is gradually adjusted to the duty cycle of the corresponding current carrying state in the fast charging mode. Conversely, based on the adjustment gradient corresponding to the degree of duty cycle deviation exceeding the preset allowable fluctuation range, the equivalent current of the charging circuit is increased in a stepwise manner until the fluctuation amplitude of the initial current boost duty cycle within the preset duty cycle transition range does not exceed the preset allowable fluctuation range. Then, the initial current boost duty cycle is gradually adjusted to the duty cycle of the corresponding current carrying state in fast charging mode according to the preset current boost duty cycle adjustment gradient. After the initial current boost duty cycle is gradually adjusted, the real-time current carrying value of the charging circuit under the current current carrying state is monitored and collected. Based on the real-time current carrying value, combined with the correction resistance value of each sampling node and the conductor thermal tolerance parameter of the corresponding charging circuit, the maximum allowable current carrying value of each sampling node is calculated, and the minimum value of the maximum allowable current carrying value of all sampling nodes is taken as the maximum safe current carrying limit of the charging circuit in the corresponding scenario of switching from slow charging mode to fast charging mode.

6. The current adaptive control system for electric vehicle charging as described in claim 1, characterized in that, The dynamic current control module includes: Within the maximum safe current carrying limit of the charging circuit, the current conduction phase angle is dynamically adjusted based on the real-time temperature and correction resistance value of each sampling node, and the temperature rise of each sampling node in the corresponding charging circuit is monitored. When the temperature rise of a certain sampling node exceeds the preset allowable temperature rise, the excess temperature rise deviation is input into the preset temperature-phase angle mapping relationship, and the corresponding current conduction phase angle is fine-tuned. The conduction time is delayed, and the equivalent current of the preset amplitude is reduced simultaneously to achieve a smooth transition from the minimum current limit of the charging circuit to the maximum safe current carrying limit.

7. The current adaptive control system for electric vehicle charging as described in claim 1, characterized in that, The dynamic current control module further includes: Within the maximum safe current carrying limit of the charging circuit, based on the real-time temperature and conductor thermal tolerance parameters of each sampling node, the maximum safe current carrying limit is mapped to the fixed current level of the corresponding charging circuit under discontinuous current limiting state according to the preset current carrying limit-level mapping rule. The duty cycle adjustment gradient is based on the fixed current level. By adjusting the current on / off duty cycle, the conduction time of the charging circuit within the preset monitoring period is controlled to achieve approximately continuous current output. If the temperature rise of a certain sampling node exceeds the preset allowable temperature rise, the system will prompt the user to switch the current fixed current range to the duty cycle range to achieve a stable transition from the rated current range to the dynamically adjustable current.

8. A current adaptive control device for charging electric vehicles, comprising an integrated structure of a current adaptive device, including a charging head, terminals, a charging housing, and cables, wherein the components work together to form the main support and conductive path of the device, and applying the current adaptive control system for charging electric vehicles as described in any one of claims 1-7, characterized in that... include: The system includes a negative temperature coefficient thermistor temperature sensor array, a differential voltage sampling unit, a current measurement unit, a pulse current excitation unit, a main control unit, a current regulation execution unit, and a communication interaction unit. The negative temperature coefficient thermistor temperature sensor array is deployed at each sampling point corresponding to the gun head, terminal, gun shell and cable in the current adaptive device, and is electrically connected to the main control unit to collect temperature data and corresponding collection timestamps of each sampling node in real time. The differential voltage sampling unit consists of a pair of differential voltage sampling points and a differential amplification and filtering circuit. The sampling points are electrically connected to the two ends of the preset test segment in the conductive path of the charging circuit, and are used to collect the potential signals at both ends of the test segment. The local voltage drop is obtained after differential operation processing. The current measurement unit uses a Hall current sensor integrated inside the charging gun housing, which is connected to the main control unit for synchronous monitoring of the real-time current and current-carrying status of the charging circuit, and completes the preliminary estimation of local resistance in conjunction with the local voltage drop. The pulse current excitation unit is connected in series in the charging circuit and controlled by the main control unit. It is used to apply a controlled current excitation with a preset amplitude and pulse width to the charging circuit. The main control unit is bidirectionally electrically connected to each of the above units and is used to execute the algorithms of the multi-node state sensing module, pulse thermal verification module, current carrying limit control module and dynamic current control module, including preliminary estimation of local resistance, temperature compensation correction, thermal response matching verification and determination of maximum allowable current carrying value. The current regulation execution unit is driven and connected in series with the main control unit in the charging circuit. It is used to receive instructions from the main control unit and realize smooth current limiting, gear switching and zero current point disconnection of the charging circuit through phase control and / or periodic on / off control. The communication interaction unit is connected to the main control unit and can interact with electric vehicles, charging piles and the back-end operation and maintenance platform. It is used to issue the maximum allowable current carrying value and report and transmit the execution results of the main control unit.

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