LLC circuit relay stick protection system and control method thereof

Abstract

The application relates to an LLC circuit relay sticking protection system and a control method thereof. The system part mainly comprises an LLC main circuit unit, a current sampling unit, a high-speed core control unit and a fault alarm unit; the current sampling unit is electrically connected with the transformer primary side of the LLC main circuit unit; the high-speed core control unit is internally provided with a high-speed analog-to-digital conversion module, a hardware comparator and a pulse control module; the high-speed analog-to-digital conversion module is used for high-frequency sampling of electric signals; the hardware comparator is used for comparing the sampled electric signals with a current reference signal in real time to complete hardware-level fault determination, and outputs a fault determination signal when a fault is determined; the pulse control module is used for instantaneously shutting off the pulse signals output to the switch tube group according to the fault determination signal; the fault alarm unit is electrically connected with the high-speed core control unit and is used for receiving the fault determination signal to realize real-time alarm. The application can solve the core problem of insufficient fault protection response speed in the prior art.

Description

Technical Field

[0001] This application relates to the field of relay protection technology, and in particular to an LLC circuit relay adhesion protection system and its control method. Background Technology

[0002] LLC resonant converters, with their high efficiency and low loss advantages brought by soft-switching characteristics, have become one of the core topologies of medium and high power electronic devices. Relays, as key components in LLC circuits that control the on / off state of the main circuit, achieve standby energy saving, and fault isolation, directly determine the operational safety of the entire system due to their reliability. However, in practical applications, relays are highly susceptible to contact sticking faults due to factors such as contact oxidation, arc erosion, and load impacts. This means that after receiving a disconnect command, the relay contacts remain closed, causing the LLC main circuit to remain conductive and triggering overcurrent. If fault detection and protection response cannot be achieved quickly, it will directly cause the burnout of core power electronic components such as switching transistors and transformers.

[0003] Existing relay protection schemes for LLC circuits have significant technical shortcomings: they rely on analog comparators to build overcurrent protection circuits, have fixed thresholds, and weak anti-interference capabilities. When the resonant frequency of the LLC circuit fluctuates or the load changes, false triggering or missed triggering is likely to occur. In addition, although some patents (such as CN114284563A) attempt to optimize the protection logic through digital controllers, the general-purpose MCUs (such as the STM32 series) used have sampling rates ≤2MSPS and core frequencies ≤72MHz, which cannot meet the real-time signal processing requirements of LLC circuits under high-frequency operating conditions (switching frequencies 50kHz~200kHz). The fault determination response time is still >50μs, making it difficult to avoid damage to core components such as switching transistors and transformers due to overcurrent.

[0004] Therefore, existing relay sticking fault protection schemes for LLC circuits, whether based on traditional overcurrent protection circuits using analog comparators or digital protection logic using general-purpose microcontrollers, all suffer from the core technical problem of insufficient fault protection response speed. They cannot match the instantaneous current change characteristics of relay sticking faults under high-frequency operating conditions of LLC circuits. The total response time for fault judgment and protection execution is too long, making it difficult to complete effective protection during the current surge caused by the fault. This fails to meet the safety protection requirements of high-frequency operation of LLC circuits and has become a key factor restricting the improvement of the reliability of LLC resonant converters.

[0005] Therefore, how to overcome the problem of insufficient fault protection response speed in existing LLC circuit relay sticking fault protection schemes is a problem to be solved in this technical field. Summary of the Invention

[0006] To address the aforementioned deficiencies or improvement needs of existing technologies, and to resolve the issue of insufficient fault protection response speed in existing LLC circuit relay sticking fault protection schemes, this application provides an LLC circuit relay sticking protection system and its control method. The core of this system is the collaborative design of a high-speed sampling unit and a high-computing-power core control unit to construct a hardware-level fast fault detection and protection response link. This simultaneously achieves accurate fault determination and real-time alarm, solving the core problem of insufficient fault protection response speed in existing technologies. The specific technical solution is as follows: The embodiments of this application adopt the following technical solutions: In a first aspect, this application provides an LLC circuit relay sticking protection system, including an LLC main circuit unit, a current sampling unit, a high-speed core control unit, and a fault alarm unit; The current sampling unit is electrically connected to the primary side of the transformer of the LLC main circuit unit. It is used to collect the real-time current signal of the main circuit and convert it into an electrical signal that is adapted to the processing of the high-speed core control unit, and to output a current reference signal. The high-speed core control unit is electrically connected to the switching transistor group of the current sampling unit and the LLC main circuit unit, respectively. The high-speed core control unit has a built-in high-speed analog-to-digital conversion module, a hardware comparator, and a pulse control module. The high-speed analog-to-digital conversion module is used for high-frequency sampling of electrical signals. The hardware comparator is used to compare the sampled electrical signals with the current reference signal in real time to complete hardware-level fault determination and output a fault determination signal when a fault is determined. The pulse control module is used to instantaneously turn off the pulse signal output to the switching transistor group according to the fault determination signal. The fault alarm unit is electrically connected to the high-speed core control unit and is used to receive fault judgment signals to achieve real-time alarm.

[0007] By adopting the above technical solutions, a relay sticking protection system is constructed, consisting of an LLC main circuit unit, a current sampling unit, a high-speed core control unit, and a fault alarm unit. This system enables full-process control of main circuit current acquisition, hardware-level fault determination, instantaneous protection, and real-time alarm. It addresses the core issue of insufficient protection response speed in existing technologies from the system architecture level, while also achieving integrated linkage between fault determination and protection execution, thereby improving the overall reliability of LLC circuit relay sticking protection.

[0008] In some implementations, the high-speed core control unit includes a TMS320F280025 DSP chip. The high-speed analog-to-digital conversion module, hardware comparator, and pulse control module are all built-in peripherals of the DSP chip. The output terminal of the hardware comparator is directly electrically connected to the trip trigger terminal of the pulse control module to achieve hardware-level linkage between fault determination and protection execution.

[0009] By adopting the above technical solution, the TMS320F280025 DSP chip is used as a high-speed core control unit. By utilizing the chip's built-in high-speed analog-to-digital converter, hardware comparator, and pulse control peripherals, the hardware-level direct linkage between fault determination and protection execution is realized, eliminating the delay of intermediate software links and significantly improving the protection response speed. At the same time, relying on the peripheral integration characteristics of a single chip, the configuration of peripheral devices is reduced, and the circuit complexity and hardware cost are lowered.

[0010] In some embodiments, the sampling rate of the high-speed analog-to-digital conversion module is not less than 10 MSPS, the core frequency of the DSP chip is not less than 100 MHz, and the core of the DSP chip integrates a filtering operation unit for anti-interference processing of the electrical signals acquired by the high-speed analog-to-digital conversion module.

[0011] By adopting the above technical solution, the sampling rate of the high-speed analog-to-digital conversion module and the core frequency of the DSP chip are limited, ensuring high-frequency and fast sampling of the main circuit current signal. At the same time, the sampling signal is subjected to anti-interference processing through the core-integrated filtering and operation unit, thereby improving the signal acquisition accuracy while ensuring the sampling rate and avoiding fault misjudgment caused by signal noise, achieving the dual effect of high-speed sampling and accurate sampling.

[0012] In some embodiments, the current sampling unit includes a current transformer and a signal conditioning circuit. The current transformer is connected in series in the primary current loop of the transformer in the LLC main circuit unit. The input terminal of the signal conditioning circuit is electrically connected to the output terminal of the current transformer, and the output terminal of the signal conditioning circuit is electrically connected to the high-speed analog-to-digital conversion module of the high-speed core control unit. The signal conditioning circuit is used to convert the current signal collected by the current transformer into a voltage sampling signal of 0~3.3V.

[0013] By adopting the above technical solution, the composition structure and signal conversion rules of the current sampling unit are clarified. The current transformer is used to achieve accurate acquisition of the main circuit current. The current signal is converted into a 0~3.3V voltage sampling signal that is compatible with the processing of the high-speed core control unit through the signal conditioning circuit. This ensures the hardware compatibility between the sampling signal and the control chip, realizes the linear and distortion-free conversion of the current signal to the electrical signal, and provides an accurate signal basis for subsequent fault diagnosis.

[0014] In some implementations, the voltage sampling signal output by the signal conditioning circuit is an OCP_DC signal, and the current reference signal is a REC_CURR signal. Both the voltage sampling signal and the current reference signal are transmitted to the high-speed analog-to-digital conversion module of the high-speed core control unit.

[0015] By adopting the above technical solution, the voltage sampling signal and the current reference signal are specifically defined as OCP_DC signal and REC_CURR signal, respectively. The specific forms of the two core signals are clarified, and the standardized transmission and processing of the sampling signal and the reference signal are realized. This ensures that the high-speed core control unit can accurately identify and compare the two signals, improves the standardization and reliability of fault judgment, and provides a clear signal reference for circuit design and debugging.

[0016] In some implementations, the filtering operation unit runs a moving average filtering algorithm with a window length of 3 to 10 points. The window length is matched with the sampling rate of the high-speed analog-to-digital conversion module and the resonant frequency of the LLC circuit, so as to achieve noise suppression and data optimization of the sampled signal without increasing the data processing delay.

[0017] By adopting the above technical solution, the filtering operation unit is limited to run the moving average filtering algorithm and matched with a reasonable window length range. The window length is adapted to the sampling rate and the resonant frequency of the LLC circuit. While effectively filtering out high-frequency noise caused by LLC circuit resonance and improving the quality of the sampled signal, it avoids the addition of extra data processing delay due to the filtering algorithm, achieves a balance between noise suppression and low-latency processing, and ensures the accuracy of fault judgment and the speed of protection response.

[0018] In some implementations, the current reference signal corresponds to a preset relay sticking fault threshold current. The hardware comparator compares the filtered voltage sampling signal with the current reference signal in real time. When the real-time current corresponding to the voltage sampling signal exceeds the fault threshold current corresponding to the current reference signal, a low-level fault determination signal is output. The pulse control module uses this fault determination signal as the sole triggering condition for trip protection.

[0019] By adopting the above technical solution, the correspondence between the current reference signal and the preset fault threshold current is clarified, the fault judgment logic of the hardware comparator is standardized, and hardware-level fault identification with voltage signal comparison as the carrier and current overcurrent judgment as the core is realized. This ensures the physical rigor of the fault judgment logic and its fit with engineering implementation. At the same time, the low-level fault judgment signal is used as the only triggering condition for trip protection to avoid false triggering of protection and improve the accuracy and uniqueness of protection execution.

[0020] In some embodiments, the LLC main circuit unit includes a DC input module, a switching transistor group, an LC resonant module, a transformer, a secondary rectifier and filter module, and a load connected in sequence. The LC resonant module cooperates with the primary side of the transformer to realize the resonant transformation of the LLC circuit.

[0021] By adopting the above technical solution, the complete composition structure of the LLC main circuit unit and the connection relationship of each module are clarified, the working mode of the LC resonant module and the transformer is standardized, the resonant transformation and normal operation of the LLC main circuit are guaranteed, a stable circuit operation foundation is provided for the relay sticking protection system, and seamless integration of the protection system and the LLC main circuit is realized, ensuring the protection system's rapid perception and response to main circuit faults.

[0022] Secondly, this application provides a control method for an LLC circuit relay sticking protection system, applied to the LLC circuit relay sticking protection system described in the first aspect, comprising: S1. Module Configuration: Configure the sampling channel for the high-speed analog-to-digital conversion module of the high-speed core control unit, and configure the pulse output parameters and trip protection trigger conditions for the pulse control module. S2. High-frequency current sampling: The current sampling unit collects the real-time current on the primary side of the LLC main circuit transformer, converts it into a voltage sampling signal and a current reference signal after signal conditioning, and transmits it to the high-speed analog-to-digital converter module to complete high-frequency sampling and filtering processing. S3. Hardware-level fault determination: The hardware comparator compares the filtered voltage sampling signal with the current reference signal in real time. If the real-time current corresponding to the voltage sampling signal exceeds the preset fault threshold current corresponding to the current reference signal, it is determined to be a relay sticking fault, and a fault determination signal is generated and output. S4. Instantaneous protection and real-time alarm: After receiving the fault determination signal, the pulse control module instantly shuts off the pulse signal output to the switching transistor group. At the same time, the high-speed core control unit transmits the fault determination signal to the fault alarm unit, which then issues a relay sticking fault alarm.

[0023] By adopting the above technical solutions, through the step-by-step execution of module configuration, high-frequency current sampling, hardware-level fault judgment, instantaneous protection and real-time alarm, the protection system can be standardized and streamlined, transforming the performance advantages of the hardware system into actual protection effects, ensuring high-speed and accurate execution of the entire process from signal acquisition to fault alarm, and completely solving the problems of slow response and low judgment accuracy of existing protection technologies.

[0024] In some implementations, in step S1, the sampling channels of the high-speed analog-to-digital conversion module are configured as ADCINA2, ADCINA8, and ADCINA9; in step S4, the response time of the pulse control module from receiving the fault determination signal to turning off the pulse signal is 20~25ns.

[0025] By adopting the above technical solution, the specific sampling channel of the high-speed analog-to-digital conversion module and the protection response time of the pulse control module are limited, realizing the dedicated configuration of the current signal acquisition channel, ensuring the targeting and accuracy of the main circuit current signal acquisition, and controlling the protection response time to 20~25ns, realizing the instantaneous response from the judgment of relay sticking fault to the protection execution, and completing effective protection in the stage of sudden current increase caused by the fault, completely avoiding the burnout of core components such as switching tubes and transformers due to overcurrent.

[0026] In summary, this application includes at least the following beneficial technical effects: 1. Significantly improved protection response speed: This invention achieves an ultra-fast response from the occurrence of relay sticking faults to the execution of main circuit protection by using high-frequency sampling of high-speed analog-to-digital conversion module, zero-delay judgment of hardware comparator, and hardware-level tripping of pulse control module. The total response time is significantly shortened compared with existing analog solutions and general microcontroller digital solutions. It can complete effective protection in the stage of sudden current increase caused by fault, completely avoid the burnout of core components such as switching transistors and transformers due to overcurrent, and greatly reduce the component damage rate. 2. Significantly improved fault diagnosis accuracy: The filtering algorithm of the high-performance computing kernel is used to process and compare the real-time threshold of the hardware comparator, which replaces the fixed threshold design of the traditional analog comparator. This effectively improves the anti-interference capability of the system, avoids the problem of false triggering or missed triggering caused by the resonant frequency fluctuation of LLC circuit and load change, and realizes accurate diagnosis of relay sticking faults. 3. Improved system integration and practicality: This invention integrates high-speed sampling, signal processing, fault diagnosis, pulse control and fault alarm functions into a high-speed core control unit, eliminating the need for additional dedicated processing chips or alarm chips, reducing the number of peripheral components, simplifying the overall circuit design, saving PCB layout area, and reducing hardware costs and the difficulty of later maintenance. 4. Optimized operation and maintenance efficiency: Through the real-time alarm function of the fault alarm unit, a fault signal can be issued as soon as a fault occurs, which makes it easy for operation and maintenance personnel to quickly locate the fault type and location, greatly shortening the fault investigation and repair time and improving the overall operation and maintenance efficiency of the LLC resonant converter system. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1A system block diagram of an LLC circuit relay adhesion protection system provided in this application embodiment; Figure 2 This is a schematic diagram of the LLC main circuit provided in an embodiment of this application; Figure 3 A schematic diagram of a relay provided in an embodiment of this application; Figure 4 This is a schematic diagram of a signal conditioning circuit provided in an embodiment of this application; Figure 5 This is a schematic diagram of the chip configuration provided in an embodiment of this application; Figure 6 A flowchart illustrating a control method for an LLC circuit relay adhesion protection system provided in this application embodiment. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Furthermore, the technical features involved in the various embodiments described below can be combined with each other as long as they do not conflict with each other.

[0030] This application provides an LLC circuit relay adhesion protection system, which aims to achieve high-speed detection, accurate judgment and instantaneous protection of LLC circuit relay adhesion faults, effectively solving the core technical problem of insufficient protection response speed in the prior art.

[0031] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Example 1

[0032] refer to Figure 1As shown in Embodiment 1 of this application, an LLC circuit relay sticking protection system is provided, including an LLC main circuit unit, a current sampling unit, a high-speed core control unit, and a fault alarm unit. The current sampling unit is electrically connected to the primary side of the transformer in the LLC main circuit unit, and is used to collect real-time current signals of the main circuit and convert them into electrical signals adapted for processing by the high-speed core control unit, and to output a current reference signal. The high-speed core control unit is electrically connected to both the current sampling unit and the switching transistor group of the LLC main circuit unit. The high-speed core control unit incorporates a high-speed analog-to-digital converter module, a hardware comparator, and a pulse control module. The high-speed analog-to-digital converter module is used for high-frequency sampling of the electrical signals. The hardware comparator is used to compare the sampled electrical signals with the current reference signal in real time to complete hardware-level fault determination, and outputs a fault determination signal when a fault is determined. The pulse control module is used to instantaneously turn off the pulse signal output to the switching transistor group according to the fault determination signal. The fault alarm unit is electrically connected to the high-speed core control unit and is used to receive the fault determination signal to achieve real-time alarm.

[0033] Specifically, the LLC main circuit unit consists of a DC input module, a switching transistor group, an LC resonant module, a transformer, a secondary rectifier and filter module, and a load connected in sequence. In this embodiment, this unit is the main circuit of a 1.5kW LLC resonant converter. The resonant inductance Lr of the LC resonant module is 10μH, and the resonant capacitance Cr is 0.1μF. The transformer has a turns ratio of 10:1, and its primary side current loop is connected in series with a current transformer for real-time current acquisition. The control terminal of the switching transistor group is electrically connected to the pulse control module of the high-speed core control unit. The switching is controlled by the PWM wave output by the pulse control module. In this embodiment, the PWM switching frequency is set to 100kHz to match the high-frequency operating requirements of the LLC circuit from 50kHz to 200kHz.

[0034] refer to Figure 2As shown, in a specific LLC main circuit setup, the DC input module includes the leftmost DCBUS+ / DCBUS- input terminals, a bus support capacitor bank (large-capacity electrolytic capacitors such as E1 / E2), a bus voltage divider resistor network (R19 / R20 / R21 / R22, etc.), and an auxiliary power relay control circuit; its function is to provide a stable DC bus voltage and realize bus voltage detection and auxiliary power control. The switching transistor bank includes six MOSFETs (Q1~Q6) in the upper and lower bridge arms and their driving circuits (DRVG_A11~DRVG_A23), and gate resistors / capacitors; its function is to invert the DC bus voltage into a high-frequency square wave to drive the subsequent LLC resonant cavity. The LC resonant module includes resonant inductors L1 / L2 / L3, a resonant capacitor bank (multiple sets of parallel capacitors on the capacitor plate), and a resonant cavity midpoint diode / absorption circuit (D3 / D4 / D10 / D11 / D20 / D21, etc.); its function is to cooperate with the transformer magnetizing inductor to realize LLC resonance, achieving soft switching and voltage conversion. The transformer includes a multi-winding transformer with a vertical center section (T2 / T3 / T5, T1A / T1B / T1C / T4A / T4B / T4C / T6A / T6B / T6C windings, etc.); its function is to achieve electrical isolation and voltage ratio transformation, coupling the high-frequency resonant voltage to the secondary side. The secondary-side rectifier and filter module includes a secondary-side synchronous rectifier / diode rectifier bridge (D5 / D6 / D7 / D12 / D13 / D14 / D15 / D16 / D17 / D22 / D23 / D24, etc.), output filter capacitor banks (C15 / C16 / C39 / C40, etc.), and output current sampling resistors (ISENSE1 / ISENSE2); its function is to rectify the high-frequency AC voltage into DC and filter it to obtain a stable output voltage. The load includes the rightmost OUT1 / OUT2 output terminals and their connectors (e.g., 1~16 pin sockets), representing the external load interface; its function is to connect the actual electrical load and consume the converter's output power.

[0035] Regarding relays, refer to... Figure 3As shown, this is a typical example of a relay sticking fault scenario. The relay group (RLY1B, RLY2B, RLY3B) consists of three double-pole double-throw relays used to control the on / off state of the output and sampling paths. RLY1B controls the connection between ISENSE2 and the sampling resistor group (RS1~RS6); RLY2B controls the direct path between ISENSE2 and OUT1; and RLY3B controls the output paths between OUT1 and OUT2. The current sampling network consists of parallel sampling resistors (RS1~RS6), a filter capacitor (C55), and ISENSE1 / ISENSE2 as the current sampling signal output terminals for acquiring the output current. The output paths are: OUT1 / OUT2 as the load output terminals, and AGND1 as analog ground. Typical manifestation of adhesion fault scenario: When RLY3B contacts stick together: even if the control command requires disconnection, the RLY3B contacts remain closed, and OUT1 and OUT2 continue to conduct; if the system needs to cut off the output or enter the protection state at this time, the main circuit current cannot be effectively isolated, which will cause overcurrent and damage core components such as switching transistors and transformers.

[0036] Furthermore, Figure 3 ISENSE1 / ISENSE2, RS1~RS6, and C55 constitute part of the current sampling unit in this embodiment, responsible for acquiring the output side current signal. The acquired current signal, after conditioning, is converted into a voltage sampling signal (OCP_DC) and a current reference signal (REC_CURR), which are then input to the high-speed core control unit (TMS320F280025) for high-speed sampling and fault determination. When relay sticking causes overcurrent, the current sampling unit can quickly capture the current surge, providing a data basis for subsequent hardware-level fault determination and protection. In this embodiment, after detecting a relay sticking fault, the pulse control module instantly shuts off the PWM wave of the LLC main circuit switching transistor group, cutting off the main circuit energy supply; combined with... Figure 3 The circuit's protection action can further link with the relay control logic: while shutting down the PWM, it attempts to drive other relays (such as RLY1B / RLY2B) to disconnect the sampling / output path, forming a dual protection of "main circuit shutdown + output path isolation", further improving system safety.

[0037] In some embodiments, the current sampling unit includes a current transformer and a signal conditioning circuit. The current transformer is connected in series in the primary current loop of the transformer in the LLC main circuit unit to acquire three real-time current signals. The input terminal of the signal conditioning circuit is electrically connected to the output terminal of the current transformer to condition the three current signals and convert them into a 0~3.3V voltage sampling signal (OCP_DC signal) and a current reference signal (REC_CURR signal) adapted to the processing of the high-speed core control unit. The two signals are then transmitted to the high-speed analog-to-digital conversion module of the high-speed core control unit. The current reference signal REC_CURR corresponds to the preset relay sticking fault threshold current.

[0038] refer to Figure 4 As shown, the current transformer acquires the real-time current signal from the primary side of the LLC main circuit transformer and outputs a SAM-11 current sampling signal. After processing by the signal conditioning circuit, the SAM-11 signal generates an OCP_DC1 voltage sampling signal and a REC_CURR1 current reference signal, both of which are 0~3.3V voltage signals, directly adapting to the ADC input range of the high-speed core control unit. Specifically, the signal conditioning circuit includes a real-time sampling branch and a reference generation branch. In the real-time sampling branch, the SAM-11 signal is output as an OCP_DC1 signal after passing through resistor R38. The OCP_DC1 signal corresponds to the real-time current of the main circuit, providing real-time current sampling data for fault determination. In the reference generation branch, the SAM-11 signal is output as a REC_CURR1 signal after being divided by resistors R42 and R43. The REC_CURR1 signal corresponds to a preset relay sticking fault threshold current, providing a reference threshold for fault determination by the hardware comparator. A multi-stage filtering network is used: resistor R42 and... Capacitor C24, resistor R43 and capacitor C30, and resistor R38 and capacitor C27 respectively constitute RC filter units to suppress high-frequency noise in the SAM-11, OCP_DC1, and REC_CURR1 signals, avoiding signal interference caused by LLC circuit resonant frequency fluctuations and load changes, while ensuring signal processing delay ≤50ns to match the 10~50μs current surge characteristics of relay sticking faults; Ground potential stabilization unit: resistor R47 connects AGND11 and AGND to achieve analog ground potential stabilization and impedance matching, avoiding signal drift and improving sampling accuracy. Through the above technical solutions, this signal conditioning circuit realizes linear conversion, noise suppression, and standardized output of the main circuit current signal, providing high-quality sampling and reference signals for the high-speed core control unit. It is the key hardware foundation for achieving high-speed sampling, accurate judgment, and instantaneous protection in this embodiment.

[0039] In some implementations, the high-speed core control unit is a TMS320F280025 DSP chip. This chip is the core control component of the system. Its built-in high-speed analog-to-digital converter module, hardware comparator (CMPSS), and pulse control module (EPWM) are native peripherals of the chip, requiring no additional external devices. Furthermore, the output of the hardware comparator is directly electrically connected to the trip trigger terminal of the pulse control module, achieving hardware-level linkage between fault determination and protection execution, eliminating delays caused by software intermediaries. In this embodiment, the high-speed analog-to-digital converter module of the DSP chip has a sampling rate of 10MSPS and a sampling period of only 100ns, enabling multiple continuous samplings during sudden current changes. The chip's core is a 32-bit C28x core with a main frequency of 100MHz, integrating a filtering operation unit. This filtering operation unit runs a moving average filtering algorithm to filter the OCP_DC voltage sampling signal acquired by the high-speed analog-to-digital converter module, achieving noise suppression and data optimization of the voltage sampling signal, with a data processing delay ≤50ns.

[0040] refer to Figure 5 As shown, in this embodiment, the high-speed core control unit uses the TMS320F280025 DSP chip U5A. The analog input pins of U5A are electrically connected to the output of the signal conditioning circuit of the current sampling unit. The specific configuration is as follows: pin A2 / C9 (pin 13) is connected to the OCP_DC3 signal, pin A1 (pin 18) is connected to the REC_CURR3 signal, and pins A8 / C11 (pin 24) and A9 / C8 (pin 28) are connected to the OCP_DC1 and OCP_DC2 signals respectively. Pins A5 / C2 (pin 17) and A6 (pin 10) are connected to the REC_CURR1 and REC_CURR2 signals respectively. The above pins are all sampling channels of the chip's built-in high-speed analog-to-digital conversion module, corresponding to the ADCINA2, ADCINA8, and ADCINA9 sampling channels, which are used to acquire multiple voltage sampling signals and current reference signals. Pin A7 / C3 (pin 23) is connected to the SAM_DCBUS signal to collect the DC bus current signal and realize synchronous monitoring of the main circuit status. The chip's built-in high-speed analog-to-digital conversion module is configured with a sampling rate of 10MSPS and a sampling period of only 100ns. It can complete multiple continuous samplings during the 10~50μs current surge stage caused by relay sticking faults, ensuring that no fault characteristics are missed.

[0041] The clock and reference circuit configuration of chip U5A is as follows: external crystal oscillator X1, capacitor C42, and inductor L1 constitute a clock oscillation circuit, providing a stable high-frequency clock signal for the chip, enabling the core main frequency to reach 100MHz, ensuring low-latency processing of filtering operations and fault judgment, with data processing latency ≤50ns; reference voltage U9, capacitors C48 and C50 constitute a voltage reference circuit, providing accurate reference voltages for the chip's VREFHI (pin 20) and VREFLO (pin 21), ensuring the sampling accuracy of the high-speed analog-to-digital conversion module and the judgment accuracy of the hardware comparator. The U5A chip's hardware comparator and pulse control module are linked: the chip's built-in hardware comparator compares the filtered voltage sampling signal acquired by the high-speed analog-to-digital converter with the current reference signal in real time. When the real-time current corresponding to the voltage sampling signal exceeds the preset fault threshold current corresponding to the current reference signal, a low-level fault judgment signal is output. This low-level fault judgment signal directly serves as the trip trigger condition for the chip's built-in pulse control module, causing the pulse control module to instantaneously shut down the PWM wave output to the LLC main circuit switching transistor group within 20~25ns, achieving hardware-level instantaneous protection without the need for software intermediate links, thus completely eliminating software delay. Through the above technical solution, this chip configuration circuit realizes a dedicated configuration for the TMS320F280025 DSP chip, deeply integrating high-speed sampling, filtering, hardware judgment, and pulse control functions into a single chip. This provides core hardware support for high-speed detection, accurate judgment, and instantaneous protection of relay sticking faults, and is the key foundation for achieving a 20~25ns ultra-fast protection response in this embodiment.

[0042] Furthermore, in some implementations, the window length of the moving average filtering algorithm is specifically 8 points. This window length is not a conventional default value in the field, but is precisely matched based on the 100MHz core clock frequency and 10MSPS sampling rate of the TMS320F280025 DSP chip and the 100kHz resonant frequency of the LLC circuit. If the window length is less than 8 points, the high-frequency noise caused by the LLC circuit resonance cannot be effectively filtered out, which can easily lead to false fault diagnosis. If the window length is greater than 8 points, the data processing delay will exceed 50ns, which cannot match the 10~50μs current change characteristics of relay sticking faults, thus sacrificing the protection response speed. The 8-point window length achieves a balance between noise suppression and low-latency processing, which is the preferred design of this solution for the high-frequency operating conditions of LLC circuits and the requirements for fast fault response.

[0043] In some implementations, the fault alarm unit is electrically connected to the signal output terminal of the high-speed core control unit, and an alarm indicator light from a host computer is used as the fault alarm component. When the relay sticking fault judgment signal transmitted by the high-speed core control unit is received, the alarm indicator light is immediately lit, realizing real-time visual alarm of the fault, which facilitates maintenance personnel to quickly locate the fault. Example 2

[0044] Based on the LLC circuit relay sticking protection system provided in Embodiment 1, this Embodiment 2 provides a control method for the LLC circuit relay sticking protection system, which is used to achieve an ultra-fast response of 20~25ns from the occurrence of a fault to the execution of protection.

[0045] refer to Figure 6 As shown, the method includes the following steps: S1 Module Configuration: Configure the parameters of the high-speed analog-to-digital converter (ADC) module and pulse control module of the TMS320F280025 DSP chip; configure the sampling channels of the high-speed ADC module as ADCINA2, ADCINA8, and ADCINA9. All three sampling channels are electrically connected to the output of the signal conditioning circuit of the current sampling unit, specifically for acquiring the OCP_DC voltage sampling signal and REC_CURR current reference signal on the primary side of the transformer; configure the PWM wave output parameters (switching frequency 100kHz) of the pulse control module, and configure the low-level fault judgment signal output by the hardware comparator as the sole trigger condition for the trip protection of the pulse control module.

[0046] S2 High-Frequency Current Sampling: The current transformer in the current sampling unit continuously collects the real-time current on the primary side of the LLC main circuit transformer. After processing by the signal conditioning circuit, it is converted into a 0~3.3V OCP_DC voltage sampling signal and a REC_CURR current reference signal. The two signals are transmitted to the high-speed analog-to-digital converter module of the DSP chip through the configured ADCINA2, ADCINA8, and ADCINA9 sampling channels. The high-speed analog-to-digital converter module performs high-frequency continuous sampling of the two signals at a sampling rate of 10MSPS. The sampled data is transmitted to the filtering and operation unit of the chip core. After filtering by the 8-point moving average filtering algorithm, the voltage sampling signal is stored and optimized, effectively avoiding signal interference caused by LLC circuit resonant frequency fluctuations and load changes, and improving sampling accuracy.

[0047] S3 Hardware-Level Fault Determination: In this embodiment, the preset fault threshold current corresponding to the current reference signal REC_CURR is 7.5A. The hardware comparator built into the DSP chip compares the filtered OCP_DC voltage sampling signal with the REC_CURR current reference signal in real time without delay. If the real-time current of the main circuit corresponding to the voltage sampling signal exceeds the 7.5A fault threshold current corresponding to the current reference signal, it is determined to be a relay sticking fault. The hardware comparator immediately outputs a low-level fault determination signal and sets the relay sticking fault flag inside the DSP chip.

[0048] S4 Instantaneous Protection and Real-time Alarm: After receiving the low-level fault judgment signal output by the hardware comparator, the pulse control module, according to the preset trip trigger condition, instantaneously shuts off the PWM wave output to the switching transistor group of the LLC main circuit unit within 20~25ns, cutting off the conduction path of the LLC main circuit, realizing hardware-level instantaneous overcurrent protection, and preventing core components such as switching transistors and transformers from burning out due to overcurrent; at the same time, the DSP chip transmits the relay sticking fault judgment signal to the fault alarm unit, and the relay sticking alarm indicator in the host computer immediately lights up, realizing real-time fault alarm. Maintenance personnel can quickly know the fault type and carry out troubleshooting through the alarm signal.

[0049] To verify the feasibility and effectiveness of the protection system and control method of this invention, in one specific embodiment, a relay sticking fault in an LLC circuit was simulated by forcibly shorting the relay contacts with hardware. The protection response speed, fault determination accuracy, and overall operating performance of the system were tested, and the test results are as follows: Protection response speed: The total response time from the hardware-forced short circuit of the relay contacts (fault occurrence) to the pulse control module shutting off the PWM wave (protection execution) is 20~25ns, which is much lower than the 50μs of existing general MCU solutions and the 100μs of traditional analog solutions. The response speed is greatly improved, and effective protection can be completed in the 10~50μs current surge stage caused by relay sticking fault, completely avoiding overcurrent damage to core components and reducing component damage rate by more than 90%. Fault determination accuracy: Under the conditions of LLC circuit resonant frequency fluctuation and load change, the system achieves error-free determination by accurately comparing the 8-point moving average filtering algorithm with the hardware comparator and using 7.5A as the fault threshold current. No false triggering or missed triggering occurred, and the determination accuracy was 100%, which solved the problems of weak anti-interference ability and low determination accuracy of the existing technology. System integration and practicality: The high-speed core control unit in this embodiment relies on the single-chip integration characteristics of the TMS320F280025 DSP chip to realize the full-process functions of high-speed sampling, filtering, hardware judgment, pulse control and fault alarm within the chip. It does not require additional FPGA or dedicated alarm chip, reducing the number of peripheral devices, saving 30% of PCB area, and reducing hardware cost and circuit design complexity. Operation and maintenance efficiency: The real-time alarm function of the fault alarm unit can send a signal as soon as a fault occurs. Operation and maintenance personnel can directly locate the relay sticking fault through the alarm signal light of the host computer, which greatly shortens the fault diagnosis and repair time and improves the overall operation and maintenance efficiency of the LLC resonant converter system.

[0050] In summary, the LLC circuit relay sticking protection system and its control method in this embodiment, through the targeted selection of the TMS320F280025 DSP chip, the hardware-level linkage design of the chip's built-in peripherals, and the deep synergy of sampling and protection logic, not only fundamentally solves the core technical problem of insufficient protection response speed in existing technologies, but also achieves a synergistic improvement in fault determination accuracy, system integration, and operation and maintenance efficiency. The technical solution in this embodiment is not a simple replacement of high-performance chips, but rather a customized configuration and deep utilization of chip resources based on the characteristics of high-frequency operating conditions of LLC circuits and the instantaneous change in relay sticking fault current. This forms an overall technical solution of hardware selection, peripheral configuration, control method, and fault response, resulting in a 20~25ns hardware-level response effect that is impossible to achieve with existing technologies.

[0051] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A relay adhesion protection system for LLC circuits, characterized in that, It includes an LLC main circuit unit, a current sampling unit, a high-speed core control unit, and a fault alarm unit; The current sampling unit is electrically connected to the primary side of the transformer of the LLC main circuit unit. It is used to collect the real-time current signal of the main circuit and convert it into an electrical signal that is adapted to the processing of the high-speed core control unit, and to output a current reference signal. The high-speed core control unit is electrically connected to the switching transistor groups of the current sampling unit and the LLC main circuit unit, respectively. The high-speed core control unit has a built-in high-speed analog-to-digital conversion module, a hardware comparator and a pulse control module. The high-speed analog-to-digital conversion module is used for high-frequency sampling of electrical signals. The hardware comparator is used to compare the sampled electrical signals with the current reference signal in real time to complete hardware-level fault determination, and outputs a fault determination signal when a fault is determined. The pulse control module is used to instantaneously shut down the pulse signal output to the switching transistor group according to the fault determination signal; The fault alarm unit is electrically connected to the high-speed core control unit and is used to receive fault judgment signals to achieve real-time alarm.

2. The LLC circuit relay adhesion protection system according to claim 1, characterized in that, The high-speed core control unit includes a TMS320F280025 DSP chip. The high-speed analog-to-digital conversion module, hardware comparator, and pulse control module are all built-in peripherals of the DSP chip. The output terminal of the hardware comparator is directly electrically connected to the trip trigger terminal of the pulse control module to realize hardware-level linkage between fault determination and protection execution.

3. The LLC circuit relay adhesion protection system according to claim 2, characterized in that, The sampling rate of the high-speed analog-to-digital converter module is not less than 10MSPS, the core frequency of the DSP chip is not less than 100MHz, and the core of the DSP chip integrates a filtering operation unit for anti-interference processing of the electrical signals acquired by the high-speed analog-to-digital converter module.

4. The LLC circuit relay adhesion protection system according to claim 1, characterized in that, The current sampling unit includes a current transformer and a signal conditioning circuit. The current transformer is connected in series in the primary current loop of the transformer in the LLC main circuit unit. The input terminal of the signal conditioning circuit is electrically connected to the output terminal of the current transformer, and the output terminal of the signal conditioning circuit is electrically connected to the high-speed analog-to-digital conversion module of the high-speed core control unit. The signal conditioning circuit is used to convert the current signal collected by the current transformer into a voltage sampling signal of 0~3.3V.

5. The LLC circuit relay adhesion protection system according to claim 4, characterized in that, The voltage sampling signal output by the signal conditioning circuit is an OCP_DC signal, and the current reference signal is a REC_CURR signal. Both the voltage sampling signal and the current reference signal are transmitted to the high-speed analog-to-digital conversion module of the high-speed core control unit.

6. The LLC circuit relay adhesion protection system according to claim 3, characterized in that, The filtering operation unit runs a moving average filtering algorithm with a window length of 3 to 10 points. The window length is matched with the sampling rate of the high-speed analog-to-digital conversion module and the resonant frequency of the LLC circuit. This algorithm is used to achieve noise suppression and data optimization of the sampled signal without increasing the data processing delay.

7. The LLC circuit relay adhesion protection system according to claim 1, characterized in that, The current reference signal corresponds to a preset relay sticking fault threshold current. The hardware comparator compares the filtered voltage sampling signal with the current reference signal in real time. When the real-time current corresponding to the voltage sampling signal exceeds the fault threshold current corresponding to the current reference signal, a low-level fault determination signal is output. The pulse control module uses this fault determination signal as the sole trigger condition for trip protection.

8. The LLC circuit relay adhesion protection system according to claim 1, characterized in that, The LLC main circuit unit includes a DC input module, a switching transistor group, an LC resonant module, a transformer, a secondary rectifier and filter module, and a load connected in sequence. The LC resonant module works in conjunction with the primary side of the transformer to realize the resonant transformation of the LLC circuit.

9. A control method for an LLC circuit relay adhesion protection system, applied to the LLC circuit relay adhesion protection system according to any one of claims 1-8, characterized in that, include: S1. Module Configuration: Configure the sampling channel for the high-speed analog-to-digital conversion module of the high-speed core control unit, and configure the pulse output parameters and trip protection trigger conditions for the pulse control module. S2. High-frequency current sampling: The current sampling unit collects the real-time current on the primary side of the LLC main circuit transformer, converts it into a voltage sampling signal and a current reference signal after signal conditioning, and transmits it to the high-speed analog-to-digital converter module to complete high-frequency sampling and filtering processing. S3. Hardware-level fault determination: The hardware comparator compares the filtered voltage sampling signal with the current reference signal in real time. If the real-time current corresponding to the voltage sampling signal exceeds the preset fault threshold current corresponding to the current reference signal, it is determined to be a relay sticking fault, and a fault determination signal is generated and output. S4. Instantaneous protection and real-time alarm: After receiving the fault determination signal, the pulse control module instantly shuts off the pulse signal output to the switching transistor group. At the same time, the high-speed core control unit transmits the fault determination signal to the fault alarm unit, which then issues a relay sticking fault alarm.

10. The control method for the LLC circuit relay adhesion protection system according to claim 9, characterized in that, In step S1, the sampling channels of the high-speed analog-to-digital converter module are configured as ADCINA2, ADCINA8, and ADCINA9; in step S4, the response time of the pulse control module from receiving the fault determination signal to turning off the pulse signal is 20~25ns.

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