Circuit and method for detection and suppression of direct-current arc faults

Abstract

The present invention provides a circuit and method for detection and suppression of direct-current arc faults, the circuit being connected to a relay, and the circuit comprising: a switching power supply module, an MCU processor module, a direct-current current signal sampling module, and a relay switch driving module. The direct-current current signal sampling module and the switching power supply module are powered by an external direct current. The switching power supply module is connected to the MCU processor module, the direct-current current signal sampling module, and the relay switch driving module. The direct-current current signal sampling module receives a current signal of a direct-current circuit to be tested and outputs an analog voltage signal, and the analog voltage signal is transmitted to a port PA0 of an MCU processor. An AD conversion module inside of the MCU converts the analog voltage signal into a digital signal. On the basis of the digital signal, the MCU processor module sends a control signal to the relay switch driving module. According to the present solution, a high-voltage wide-range input is used, thus attaining stable performance, low ripple, and low noise, achieving detection accuracy to a milliampere level, providing reliable performance and a simple structure, and saving costs.

Description

DC arc fault detection and elimination circuit and detection and elimination method Technical Field

[0001] This invention relates to the fields of DC circuit control, circuit fault detection and circuit safety, and particularly to a DC arc fault detection and elimination circuit and a detection and elimination method. Background Technology

[0002] Arcing faults, caused by problems with the insulation performance of wires and cables, can damage power supply and distribution systems and electrical equipment. Based on the nature of the power system in which the arcing fault occurs, they can be classified as AC arcing faults and DC arcing faults. Arcing faults are often accompanied by sparks and high temperatures, which can further damage the insulation of wires and cables, and even cause electrical fires.

[0003] The characteristics of DC arc faults differ significantly from those of AC arc faults: AC arc currents are periodic and exhibit a "zero-crossing zone" at zero crossings; while DC arc currents lack periodicity, the concept of a fundamental wave is absent, and they possess strong randomness and non-stationarity. Therefore, general methods for detecting and eliminating AC arc faults are not applicable to detecting DC arc faults. Furthermore, because DC arcs lack zero crossings, they are difficult to extinguish. If not extinguished promptly, prolonged arcing may occur, leading to fault expansion. Therefore, the detection and elimination of DC arc faults require greater accuracy and speed.

[0004] The DC arc detection and elimination circuits commonly used in existing technologies have certain problems:

[0005] For the power supply section, a DC-DC converter is used. Simple and safe DC-DC low-voltage power supplies are preferred. High-voltage DC-DC power supplies are more complex to implement and generate more noise interference.

[0006] DC current signal acquisition section: For DC currents with a range of tens of amperes, Hall current detection sensors are used, but the DC detection accuracy is insufficient and cannot reach the milliampere level.

[0007] In terms of eliminating circuit action drive, the existing technology often adopts a multi-coil tripping mechanism. The tripping mechanism uses multiple coils, one for opening and one for closing, which has a position protection function, but the structure is generally complex. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a DC arc fault detection and elimination circuit and a detection and elimination method. Specifically, this invention provides the following technical solution:

[0009] On one hand, a DC arc fault detection and elimination circuit is provided, wherein the detection and elimination circuit is connected to a relay, and the relay is connected to a load circuit. The detection and elimination circuit includes: a switching power supply module, an MCU processor module, a DC current signal sampling module, and a relay switch driving module.

[0010] The DC current signal sampling module and the switching power supply module are powered by an external DC power supply; the switching power supply module is connected to the MCU processor module, the DC current signal sampling module and the relay switch drive module; the MCU processor is a 20-pin Cortex-4 core MCU.

[0011] The DC current signal sampling module receives the current signal of the DC circuit under test and outputs an analog voltage signal. The analog voltage signal is transmitted to the PA0 port of the MCU processor and converted into a digital signal by the internal AD converter of the MCU. The MCU processor module sends a control signal to the relay switch drive module based on the digital signal, thereby controlling the opening and closing of the relay to perform arc fault elimination action on the load circuit.

[0012] The switching power supply module is a high-voltage DC-DC conversion circuit.

[0013] Preferably, the core of the DC current signal sampling module adopts an 8-pin chip U1; it should be noted that the chip U1 can be an 8-pin ACS712 chip, or a 6-pin chip TMR7307 or WCLTMR that can achieve similar functions.

[0014] Pins 1 and 2 of chip U1 are connected to the positive terminal of the DC current to be detected. Pins 3 and 4 of chip U1 are connected to pin 4, L_OUT, of relay U7. The VCC pin of chip U1 is connected to the power supply VCC of the switching power supply module. The VIOUT pin of U1 is connected in series with resistor RF1 and diode D1IN, and then directly outputs to the PA0 terminal of the MCU processor. The FILTER pin of chip U1 is grounded through capacitor CF. Resistor RF1 and diode D1IN are grounded through series resistor R3. Diode D1IN is grounded through series capacitor C14.

[0015] Preferably, the switching power supply module is connected to a wide DC voltage input through a safety protection circuit unit and outputs low-voltage DC to power the multiple modules connected to it; the core of the switching power supply module adopts a DC-DC chip U3;

[0016] The VIN pin of chip U3 is connected to the positive terminal of the input DC power supply; a resistor R1 is connected in parallel between the VIN and VDD pins of chip U3; the FB pin of chip U3 is connected in series with a resistor R3 and then grounded; the CS pin of chip U3 is connected in series with a resistor R111 and an inductor L2, serving as the positive terminal of the output voltage; the VSS pin of chip U3 is connected in series with the negative terminal of Schottky diode D17, with the positive terminal of D17 serving as the negative terminal of the output voltage; the negative terminal of D17 is connected between resistor R111 and inductor L2; a polarized capacitor C14333 is connected between the negative terminal of D17 and inductor L2, where C14333... The positive terminal of the capacitor is connected to inductor L2; the polarized capacitor C14333 is connected in parallel with resistor R10; the VDD pin of chip U3 is connected in series with a resistor and the negative terminal of Schottky diode D16, the positive terminal of D16 is connected to the positive terminal of the output voltage, the VDD pin of chip U3 is connected in series with a resistor and then connected to the positive terminal of the input DC power supply; the FB pin of chip U3 is connected to the positive terminal of the output voltage through resistor R4; the VDD pin of chip U3 is connected between resistor R111 and inductor L2 through capacitor C1422, and is also connected to the negative terminal of D17; the positive terminal of D17 and the negative terminal of polarized capacitor C14333 are grounded.

[0017] Preferably, the safety protection circuit unit consists of a varistor MOV1, a capacitor XC1, and a polarized capacitor C122;

[0018] The varistor MOV1 is connected in parallel with the capacitor XC1. One end of the capacitor XC1 is connected to the positive terminal of the polarized capacitor C122 and also to the positive terminal of the input DC power supply. The other end of the capacitor XC1 is connected to the negative terminal of the input DC power supply. The negative terminal of the capacitor C122 is grounded.

[0019] Preferably, the switching power supply module uses an energy integration method when performing voltage conversion.

[0020] Preferably, in the MCU processor module, the PA7 pin of the MCU processor sends a DR signal to drive the relay to turn off the power supply to the circuit; the PB1 pin of the MCU processor sends an R_DR signal to drive the relay to turn on the power supply to the circuit.

[0021] The PA1 pin of the MCU processor is connected to the positive terminal of the input DC power supply in sequence through diode D14, resistor R26, transistor Q3, diode D13, and parallel resistors R4 and R6. Specifically, the PA1 pin is connected to the positive terminal of diode D14, the negative terminal of diode D14 is connected to one end of resistor R26, the other end of R26 is connected to the base of transistor Q3, the emitter of transistor Q3 is grounded, the collector of transistor Q3 is connected to the negative terminal of diode D13, and the positive terminal of diode D13 is connected in series with the parallel resistors R4 and R6.

[0022] Crystal oscillator Y11 is connected between the PF0 and PF1 pins of the MCU processor. The two ends of crystal oscillator Y11 are grounded through capacitor C8 and capacitor C17 respectively.

[0023] Preferably, the MCU processor module further includes a button switch circuit, which comprises a button switch S1 and a button switch S2:

[0024] Push-button switch S1 is connected in series with resistor R10, and push-button switch S2 is connected in series with resistor R9. These two series lines are then connected in parallel, and then connected in parallel with the line that is connected in series with capacitor C2 and resistor R8. The NRST pin of the MCU processor is connected between capacitor C2 and resistor R8. The PA2 pin of the MCU processor is connected between push-button switch S2 and resistor R9. The PA3 pin of the MCU processor is connected between push-button switch S1 and resistor R10. The end of capacitor C2 connected to push-button switches S1 and S2 is grounded together. The end of resistors R8, R9 and R10 is connected to the positive terminal of the 5V to 3.3V power supply module output voltage.

[0025] Preferably, the MCU processor module further includes a status indication circuit, wherein PA4 of the MCU processor is connected to the negative terminal of LED D6, and the positive terminal of LED D6 is connected in series with resistor R22 and then connected to the positive terminal of the output voltage of the 5V to 3.3V power supply module.

[0026] The status indicator circuit has three states: State 1, normal power supply or the line has been restored to normal power supply; State 2, there is a fault arc in the line; State 3, the fault arc in the line has been eliminated.

[0027] Preferably, the relay switch driving module includes a relay driver chip U4;

[0028] The relay off signal is generated from pin PA7 of the MCU processor and connected to pin IA of the relay driver chip U4; the relay on signal is generated from pin PB1 of the MCU processor and connected to pin IB of the relay driver chip U4; pin 1 of the relay driver chip U4 is connected to pin 6 of the relay U7, and pin 4 of the relay driver chip U4 is connected to pin 1 of the relay U7; pin OA of the relay driver chip U4 is connected to pin 1 of the relay U7; pin OB of the relay driver chip U4 is connected to pin 6 of the relay U7.

[0029] Preferably, the process of the MCU processor driving the relay is as follows:

[0030] When the MCU processor sends a shutdown signal, it outputs a DR signal through the PA7 pin of the MCU processor to the IA pin of the relay driver chip U4. Then, the OA pin of the relay driver chip U4 outputs a high level, driving the relay U7 to turn off.

[0031] When the MCU processor sends an on signal, the PB1 pin of the MCU processor outputs the R_DR signal to the IB pin of the relay driver chip U4. Then, the OB pin of the relay driver chip U4 outputs a high level, driving the relay U7 to turn on the circuit.

[0032] On the other hand, the present invention also provides a method for detecting and eliminating DC arc faults, which is applied to the DC arc fault detection and elimination circuit described above, the method comprising:

[0033] S1. The frequency domain current signal obtained by the DC current signal sampling module is preprocessed and then smoothed and filtered.

[0034] S2. Extract features from the smoothed and filtered signal to obtain current features;

[0035] S3. Based on the current characteristics, determine whether it is a parallel arc or a series arc; if it is a parallel arc, send a relay disconnect signal; if it is a series arc, proceed to step S4.

[0036] S4. Further judgment is made on the series arc based on the deep learning model, and the multi-cycle judgment array is recorded;

[0037] S5. Determine whether to send a relay disconnect signal based on a multi-cycle judgment array.

[0038] Compared with existing technologies, this solution has at least the following beneficial effects:

[0039] The high-precision DC current sampling circuit design provided in this solution achieves milliampere-level accuracy, reliable performance, simple structure, and cost savings.

[0040] This solution uses a magnetic latching relay. When the circuit power supply is interrupted or lost, the state of the DC fault arc protection device will not change. When the power supply is restored, the protector returns to the state before the power outage, thus not affecting the power consumption of connected equipment. Using a relay driver chip and a relay to control the on / off state of the power supply circuit results in a simple structure and cost-effectiveness.

[0041] This solution uses high-voltage input, wide-voltage input DC-DC voltage conversion, stable performance, low ripple, low noise, and can provide high-quality power supply to various MCUs on the PCBA. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0043] Figure 1 is a structural diagram of the DC arc fault detection and elimination circuit according to an embodiment of the present invention;

[0044] Figure 2 shows the power module circuit structure according to an embodiment of the present invention;

[0045] Figure 3 shows the structure of the 5V to 3.3V power supply module according to an embodiment of the present invention;

[0046] Figure 4 shows the microprocessor module circuit of an embodiment of the present invention;

[0047] Figure 5 shows the circuit structure of the current signal acquisition and arc fault signal sampling module according to an embodiment of the present invention;

[0048] Figure 6 shows the relay driving and switch power supply circuit structure according to an embodiment of the present invention;

[0049] Figure 7 is a schematic diagram of the arc fault diagnosis process according to an embodiment of the present invention;

[0050] Figure 8 is a flowchart of the arc fault diagnosis method according to an embodiment of the present invention. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the figures. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0052] The following detailed description of the main circuit modules and detection methods of this solution, using a specific embodiment, is provided. This solution mainly consists of four parts, as shown in Figure 1: a DC-DC switching power supply module, a main control MCU processor, a high-speed, high-precision DC current signal sampling module, and a relay switch drive module.

[0053] In addition, it includes relays used in conjunction with the components, and the load circuits controlled by the relays. The DC current signal sampling module and the switching power supply module are powered by an external DC source. The switching power supply module connects the MCU processor, the DC current signal sampling module, and the relay switch driver module, providing a stable power supply for each module circuit. The DC current signal sampling module transmits the sampled signal to the MCU processor, which then sends control signals to the relay switch driver module, further controlling the opening and closing actions of the relays to perform arc fault elimination actions on the load circuit.

[0054] As shown in Figure 1, a DC current sampling circuit, a relay switch drive circuit, and a relay are added between the DC power supply and the load. The relay is driven by a signal from the MCU to the relay switch drive circuit. The sampled current signal collected by the DC current signal sampling module is sent to the MCU processor. After analysis and processing by the MCU processor, it determines whether there is an arc fault and then sends a signal to the relay switch drive module. The relay switch drive circuit sends on / off commands to the relay to determine whether to connect or disconnect the load circuit.

[0055] The circuit structure of each part will be described in detail below.

[0056] 1. Switching power supply module

[0057] In this embodiment, the switching power supply module is designed as a high-voltage DC-DC converter circuit. Referring to Figure 2, this module can accept a wide voltage input from 15V to 120V DC. The power supply is protected by a safety circuit consisting of a varistor MOV1, capacitor XC1, and polarized capacitor C122. Through the DC-DC chip U3 and peripheral circuitry, a low-voltage 5V or 3V DC power supply is obtained to power other electronic components on the PCB. Here, the U3 chip can be a DC-DC chip such as the H6253C.

[0058] In the safety protection circuit, the varistor MOV1 and capacitor XC1 are connected in parallel, and then connected in parallel to a polarized capacitor C122 grounded. One end of capacitor XC1 is connected to the positive terminal of polarized capacitor C122, and the negative terminal of C122 is grounded. The other end of capacitor XC1, N_OUT, can be connected to the battery to be charged. In a more preferred embodiment, the other end of XC1 can be connected to the N-terminal (negative terminal) output terminal of the charging protection circuit (i.e., PCBA) and directly connected to the N-terminal (negative terminal) input terminal of the rechargeable battery.

[0059] The VIN terminal of chip U3 is connected to the positive terminal of polarized capacitor C122, which is also the positive terminal of the input DC power supply; a resistor R1 is connected in parallel between the VIN and VDD terminals of U3; the FB terminal of U3 is connected in series with a resistor R3 and then grounded; the CS terminal of U3 is connected in series with a resistor R111 and an inductor L2, serving as the positive terminal of the output voltage; the VSS terminal of U3 is connected in series with the negative terminal of Schottky diode D17, with the positive terminal of D17 serving as the negative terminal of the output voltage; the negative terminal of diode D17 is connected between resistor R111 and inductor L2; a polarized capacitor C14333 is connected between the negative terminal of D17 and inductor L2, with the positive terminal of C14333 connected to inductor L2; the polarized capacitor C14333 is also connected in parallel with resistor R10; the V... The DD pin is connected in series with resistor R2 and the negative terminal of Schottky diode D16. The positive terminal of D16 is connected to the positive terminal of the output voltage. The VDD pin of chip U3 is connected in series with capacitor C1422 and then connected to the positive terminal of the input DC power supply. The FB terminal of U3 is connected to the positive terminal of the output voltage through resistor R4, which is also the other end of inductor L2 (one end of inductor L2 is connected to resistor R111, and the other end serves as the positive terminal of the output voltage). The VDD terminal of U3 is connected to the other end of resistor R111 through capacitor C1422 (one end of resistor R111 is connected to the CS terminal of U3, and the other end is connected to one end of inductor L2), and is also connected to the negative terminal of D17. The positive terminal of diode D17 is grounded, and the negative terminal of polarized capacitor C14333 is grounded.

[0060] The proposed switching power supply module utilizes a DC-DC chip interface circuit to achieve excellent wide voltage input processing and compatibility, adapting to a wide range of DC input voltages and suitable for DC-DC conversion across different DC voltage ranges. The module's greatest technical advantage lies in its professional ASIC, enabling rapid response to fluctuating DC input voltages. Even with input voltages constantly changing from 15V to 96V, the power chip can adapt to these voltage variations, ensuring a stable output of 5V and 3.3V DC constant voltage. This switching power supply module achieves voltage conversion through energy integration.

[0061] Right now Based on the law of conservation of energy, and by sampling the high-speed input voltage signal, the highest efficiency voltage conversion of the DC-DC converter is achieved to adapt to the jump in input voltage; where U(t) represents the voltage of the DC-DC circuit input that changes with time, and R represents the load resistance at the input of the DC-DC circuit.

[0062] The switching power supply module designed in this embodiment has low noise, allows a wide range of DC voltage input, can meet DC voltage input with at least 15V to 96V fluctuations, and outputs a stable DC power supply voltage of 5V or 3.3V. The circuit is simple and reliable, and has cost advantages.

[0063] 2. MCU processor module

[0064] In this embodiment, the core processor of the MCU processor module is a 32-bit MCU with AD conversion.

[0065] As shown in Figure 3, the current sensor samples the analog current signal and inputs it to the MCU through the PA0 interface. The MCU uses its built-in 32-bit AD converter to convert the analog continuous current signal into a digital discontinuous signal. The main purpose of using 32-bit AD conversion is to improve the accuracy of analog-to-digital conversion and to obtain accurate current signal values ​​as much as possible. This allows the MCU to accurately detect the fault arc current characteristic signal contained in the circuit current. After the MCU obtains the current signal through the PA0 pin and performs digital-to-analog conversion, it first performs performance analysis and calculation using a neural network deep learning model and multi-feature fusion rule algorithm contained in the MCU embedded program. Then, it determines whether a fault arc has occurred in the current loop, thereby determining whether to shut down the power supply.

[0066] The hardware circuitry in this section incorporates two push-button switches, S1 and S2, which allow for manual switching of power supply. The main function of the TEST manual switch (S1 in Figure 4) is to simulate a fault arc signal in the current loop. This fault arc signal is then sampled by a current sensor (chip U1 in Figure 5) and input to the MCU. The MCU should detect the fault arc signal and drive the relay to cut off the power supply, ensuring electrical safety. The RESET button's function is as follows: if the MCU detects no fault arc signal in the current sampling signal, manually pressing the RESET button (S2 in Figure 4) will cause the MCU to close the relay, restoring normal power supply to the current loop.

[0067] S1 and S2 correspond to the two buttons on the casing, used for switching the circuit on and off, and also for testing whether the system is working properly. Pressing S1 generates an Off_Key signal, corresponding to PA7 issuing a Power_Off signal, turning off the circuit. Pressing S2 generates an On_Key signal, corresponding to PB1's Power_On signal, turning on the circuit. This achieves the same effect as manual button operation and automatic switching signals from AD sampling. The circuit design for this part is as follows:

[0068] S1 is connected in series with resistor R10, and S2 is connected in series with resistor R9. The two lines are then connected in parallel, and then connected in parallel with the line that is connected in series with capacitor C2 and resistor R8. The NRST pin of the MCU is connected between capacitor C2 and resistor R8, the PA2 pin is connected between S2 and resistor R9, and the PA3 pin is connected between S1 and resistor R10. One end of capacitor C2 (the other end of C2 is connected to resistor R8) and one end of S1 and S2 are grounded, and the other ends of resistors R8, R9, and R10 are connected to the positive terminal of the 5V to 3.3V power supply module on the circuit board.

[0069] The path connecting PA4 of the MCU to LED D6 serves as an indicator light. Its main function is to indicate different states of the current loop as determined by the MCU. In this embodiment, the states can be set to three: State 1: Normal power supply state (relay closed), or the line has returned to normal power supply; State 2: Fault arc state in the line (relay open); State 3: Fault arc in the line has been eliminated (relay open).

[0070] The MCU's PA0 pin receives an analog voltage signal from the sampling circuit. This analog voltage signal is input to the MCU's PA0 pin, and after the MCU's internal ADC converts the analog voltage signal from the sampling circuit into a digital signal, the MCU processes it and determines the arc signal. Then, the MCU sends a Power_Off signal (DR signal in Figure 3) through PA7 to drive the relay to turn off the circuit power supply. The MCU's PB1 pin is connected to the relay driver chip U4, which sends a Power_On signal (R_DR signal in Figure 3) to drive the relay to turn on the circuit power supply.

[0071] The MCU's PA1 pin is connected sequentially to the positive input power supply IN_L via diode D14, resistor R26, transistor Q3, diode D13, and parallel resistors R4 and R6. Specifically, PA1 is connected to the positive terminal of D14, the negative terminal of D14 is connected to one end of resistor R26, the other end of R26 is connected to the base of transistor Q3, the emitter of Q3 is grounded, the collector of Q3 is connected to the negative terminal of diode D13, and the positive terminal of D13 is connected in series with the parallel resistors R4 and R6.

[0072] Crystal oscillator Y11 is connected between the PF0 and PF1 pins of the MCU. The two ends of crystal oscillator Y11 are grounded through capacitors C8 and C17 respectively.

[0073] MCU processor selection and control process:

[0074] In this embodiment, an economical and efficient intelligent AI chip is used. Since DC circuit fault arc diagnosis not only requires a fast and efficient deep neural network learning model and multi-feature fusion rule computing power, but is also affected by product size and product cost limitations, it is crucial to determine a suitable intelligent algorithm chip for DC circuit fault arc diagnosis. Chips with sufficient computing power cannot be used because they have many pins, large size, and high cost, while chips that meet the product requirements mostly have insufficient computing power, resulting in delayed and incorrect judgment of thermal DC circuit fault arcs. In this embodiment, a 20-pin MCU based on the ARM architecture and Cortex-4 core is used to meet the requirements of DC circuit fault arc diagnosis.

[0075] As shown in Figures 6 and 7, arc fault detection mainly consists of four stages:

[0076] (1) Current signal sampling stage: Realize the sampling of the battery circuit current analog signal; The current signal of the battery pack is sampled as an analog signal after passing through the current transformer;

[0077] (2) Signal analog-to-digital conversion: Based on a high-precision, fast, multi-channel AD converter, analog current signals are converted into digital current signals.

[0078] (3) Then, the digital current signal is transformed in the time-frequency domain to convert the suitable current signal into a frequency-domain current characteristic signal. Here, the time-frequency domain transformation can be implemented using, for example, wavelet transform, and the energy peak signal within a specified frequency range is selected as the current characteristic signal through wavelet transform. Wavelet transform can be implemented using methods in the prior art.

[0079] (4) Input the frequency domain current characteristic signal into the intelligent AI chip for neural network model learning and calculation, and make judgments based on feature rules to determine whether the battery has signs of thermal runaway. The neural network model can be implemented using, for example, a two-layer 15×15 neural network. The specific network model can be implemented by training an existing network model with an arc fault dataset.

[0080] More preferably, the process of feature extraction and fault diagnosis using a network model is as follows:

[0081] (1) Preprocess the frequency domain current characteristic signal and then perform smoothing filtering;

[0082] (2) Extract features from the smoothed and filtered signal to obtain current features;

[0083] (3) Based on the current characteristics, determine whether it is a parallel arc or a series arc; if it is a parallel arc, proceed to the final judgment and send a relay disconnect signal; if it is a series arc, proceed to the next step.

[0084] (4) Further judgment is made on the series arc based on the deep learning model, and the multi-cycle judgment array is recorded;

[0085] (5) Determine whether to send a relay disconnect signal based on a multi-cycle judgment array. Furthermore, the multi-cycle method can sample 8 current half-cycles (10ms per cycle, 5ms for half-cycles). The neural network performs one operation every half-cycle, that is, performs 8 judgments. If multiple outputs in the 8 outputs are "fault" (e.g., 5 or 6 times), it is considered that there is an arc fault in the current, and the MCU outputs a disconnect command, that is, the PA7 pin of the MCU issues a DR command to disconnect. Using multi-cycle operation can effectively reduce the probability of malfunction.

[0086] It should be further explained here that, for specific network models, existing models in the prior art can be used to train the network model using historical data on the type of fault arc and the corresponding current characteristics. This part is not within the scope of this solution and will not be elaborated further.

[0087] 3. DC current signal sampling module

[0088] The circuit module structure is shown in Figure 4. The analog voltage signal, after sampling and processing, is sent to the PA0 port of the MCU processor. The sampling section samples the current signal, which is then converted into a digital signal by the MCU via A / D conversion at PA0 for further processing. This circuit module uses a high-precision DC current sensor. The current sensor can be, for example, an 8-pin ACS712, a 6-pin TMR7307, or a 6-pin WCLTMR, etc. This embodiment uses an 8-pin chip as an example.

[0089] Pins 1 and 2 of chip U1 are connected to the input current IN_L (i.e., the positive terminal). Here, the input circuit is also the current of the DC power supply being detected. Pins 3 and 4 of U1 are connected to pin 4 of relay U7, i.e., the L_OUT terminal of U7. The output of these two pins is output to the rechargeable battery through the relay. The VCC terminal of U1 is connected to the power input VCC (5V). The VIOUT terminal of U1 is connected in series with resistor RF1 and diode D1IN, and then output to the PA0 terminal of the MCU processor. The FILTER pin of U1 is grounded through capacitor CF. Resistor RF1 and diode D1IN are grounded through series resistor R3. Diode D1IN is grounded through series capacitor C14.

[0090] The coordinated operation of this circuit module U1 and the internal AD converter of the MCU enables high-precision current signal sampling, ensuring that the MCU unit can effectively detect arc fault signals.

[0091] 4. Relay switch driver module

[0092] Referring to Figure 5, the relay switch driver module uses U2 (i.e., the MCU processor) to control the relay driver chip U4. The relay driver chip U4 controls the on and off states of the relay. Chip U4 can be, for example, the CN8023 chip. The relay off signal is generated from pin PA7 of the MCU processor and connected to pin IA (i.e., pin 3) of the relay driver chip U4; the relay on signal is generated from pin PB1 of the MCU processor and connected to pin IB (i.e., pin 6) of the relay driver chip U4. Pin 1 of U4 is connected to pin 6 of relay U7, and pin 4 of U4 is connected to pin 1 of relay U7. Pin OA of the relay driver chip U4 is connected to pin 1 of relay U7, and pin OB of the relay driver chip U4 is connected to pin 6 of relay U7.

[0093] The specific driving process for the MCU to issue on / off signals is as follows:

[0094] When the MCU sends an off signal, it outputs the DR signal through the PA7 pin of the MCU processor to the IA pin of the relay driver chip U4. Then, the OA pin of the relay driver chip U4 outputs a high level, driving the relay U7 to turn off.

[0095] When the MCU sends an on signal, the PB1 pin of the MCU processor outputs the R_DR signal to pin 6 (IB) of the relay driver chip U4. Then, pin 1 (OB) of the relay driver chip U4 outputs a high level, driving the relay U7 to connect the circuit.

[0096] In this embodiment, a magnetic latching relay is more preferably used, as it offers reliable performance.

[0097] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A DC arc fault detection and elimination circuit, characterized in that, The detection elimination circuit is connected to a relay, and the relay is connected to a load circuit. The detection elimination circuit includes: a switching power supply module, an MCU processor module, a DC current signal sampling module, and a relay switch driving module. The DC current signal sampling module and the switching power supply module are powered by an external DC power supply; the switching power supply module is connected to the MCU processor module, the DC current signal sampling module and the relay switch drive module; the MCU processor is a 20-pin Cortex-4 core MCU. The DC current signal sampling module receives the current signal of the DC circuit under test and outputs an analog voltage signal. The analog voltage signal is input to the PA0 port of the MCU processor and converted into a digital signal by the internal AD converter of the MCU. The MCU processor module sends a control signal to the relay switch drive module based on the digital signal, thereby controlling the opening and closing of the relay to perform arc fault elimination action on the load circuit. The switching power supply module is a high-voltage DC-DC conversion circuit.

2. The detection elimination circuit according to claim 1, characterized in that, The core of the DC current signal sampling module adopts an 8-pin chip U1; Pins 1 and 2 of chip U1 are connected to the positive terminal of the DC current to be detected. Pins 3 and 4 of chip U1 are connected to pin 4, L_OUT, of relay U7. The VCC pin of chip U1 is connected to the power supply VCC of the switching power supply module. The VIOUT pin of U1 is connected in series with resistor RF1 and diode D1IN, and then directly outputs to the PA0 terminal of the MCU processor. The FILTER pin of chip U1 is grounded through capacitor CF. Resistor RF1 and diode D1IN are grounded through series resistor R3. Diode D1IN is grounded through series capacitor C14.

3. The detection elimination circuit according to claim 1, characterized in that, The switching power supply module is connected to a wide DC voltage input through a safety protection circuit unit and outputs low-voltage DC to power multiple modules connected to it; the core of the switching power supply module adopts a DC-DC chip U3; The VIN pin of chip U3 is connected to the positive terminal of the input DC power supply; a resistor R1 is connected in parallel between the VIN and VDD pins of chip U3; the FB pin of chip U3 is connected in series with a resistor R3 and then grounded; the CS pin of chip U3 is connected in series with a resistor R111 and an inductor L2, serving as the positive terminal of the output voltage; the VSS pin of chip U3 is connected in series with the negative terminal of Schottky diode D17, with the positive terminal of D17 serving as the negative terminal of the output voltage; the negative terminal of D17 is connected between resistor R111 and inductor L2; a polarized capacitor C14333 is connected between the negative terminal of D17 and inductor L2, with the positive terminal of C14333 connected to... Inductor L2; polarized capacitor C14333 is connected in parallel with resistor R10; the VDD pin of chip U3 is connected in series with resistor R2 and the negative terminal of Schottky diode D16, with the positive terminal of D16 connected to the positive terminal of the output voltage; the VDD pin of chip U3 is connected in series with capacitor C1422 and then connected to the positive terminal of the input DC power supply; the FB pin of chip U3 is connected to the positive terminal of the output voltage through resistor R4; the VDD pin of chip U3 is connected between resistor R111 and inductor L2 through capacitor C1422, and is also connected to the negative terminal of D17; the positive terminal of D17 and the negative terminal of polarized capacitor C14333 are grounded.

4. The detection elimination circuit according to claim 3, characterized in that, The safety protection circuit unit consists of a varistor MOV1, a capacitor XC1, and a polarized capacitor C122. The varistor MOV1 is connected in parallel with the capacitor XC1. One end of the capacitor XC1 is connected to the positive terminal of the polarized capacitor C122 and also to the positive terminal of the input DC power supply. The other end of the capacitor XC1 is connected to the negative terminal of the input DC power supply. The negative terminal of the capacitor C122 is grounded.

5. The detection elimination circuit according to claim 3, characterized in that, The switching power supply module uses an energy integration method when performing voltage conversion.

6. The detection elimination circuit according to claim 1, characterized in that, In the MCU processor module, the PA7 pin of the MCU processor sends a DR signal to drive the relay to turn off the power supply to the circuit; the PB1 pin of the MCU processor sends an R_DR signal to drive the relay to turn on the power supply to the circuit. The PA1 pin of the MCU processor is connected to the positive terminal of the input DC power supply in sequence through diode D14, resistor R26, transistor Q3, diode D13, and parallel resistors R4 and R6. Specifically, the PA1 pin is connected to the positive terminal of diode D14, the negative terminal of diode D14 is connected to one end of resistor R26, the other end of R26 is connected to the base of transistor Q3, the emitter of transistor Q3 is grounded, the collector of transistor Q3 is connected to the negative terminal of diode D13, and the positive terminal of diode D13 is connected in series with the parallel resistors R4 and R6. Crystal oscillator Y11 is connected between the PF0 and PF1 pins of the MCU processor. The two ends of crystal oscillator Y11 are grounded through capacitor C8 and capacitor C17 respectively.

7. The detection elimination circuit according to claim 1, characterized in that, The MCU processor module also includes a button switch circuit, which comprises button switch S1 and button switch S2: Push-button switch S1 is connected in series with resistor R10, and push-button switch S2 is connected in series with resistor R9. These two series lines are then connected in parallel, and then connected in parallel with the line that is connected in series with capacitor C2 and resistor R8. The NRST pin of the MCU processor is connected between capacitor C2 and resistor R8. The PA2 pin of the MCU processor is connected between push-button switch S2 and resistor R9. The PA3 pin of the MCU processor is connected between push-button switch S1 and resistor R10. The end of capacitor C2 connected to push-button switches S1 and S2 is grounded together. The end of resistors R8, R9 and R10 is connected to the positive terminal of the 5V to 3.3V power supply module output voltage.

8. The detection elimination circuit according to claim 1, characterized in that, The MCU processor module also includes a status indication circuit, in which PA4 of the MCU processor is connected to the negative terminal of LED D6, and the positive terminal of LED D6 is connected in series with resistor R22 and then connected to the positive terminal of the output voltage of the 5V to 3.3V power supply module. The status indicator circuit has three states: State 1, normal power supply or the line has been restored to normal power supply; State 2, there is a fault arc in the line; State 3, the fault arc in the line has been eliminated.

9. The detection elimination circuit according to claim 1, characterized in that, The relay switch driving module includes a relay driver chip U4; The relay off signal is generated from pin PA7 of the MCU processor and connected to pin IA of the relay driver chip U4; the relay on signal is generated from pin PB1 of the MCU processor and connected to pin IB of the relay driver chip U4; pin 1 of the relay driver chip U4 is connected to pin 6 of the relay U7, and pin 4 of the relay driver chip U4 is connected to pin 1 of the relay U7; pin OA of the relay driver chip U4 is connected to pin 1 of the relay U7; pin OB of the relay driver chip U4 is connected to pin 6 of the relay U7.

10. A method for detecting and eliminating DC arc faults, characterized in that, The method is applied to the DC arc fault detection and elimination circuit according to any one of claims 1-9, and the method includes: S1. The frequency domain current signal obtained by the DC current signal sampling module is preprocessed and then smoothed and filtered. S2. Extract features from the smoothed and filtered signal to obtain current features; S3. Based on the current characteristics, determine whether it is a parallel arc or a series arc; if it is a parallel arc, send a relay disconnect signal; if it is a series arc, proceed to step S4. S4. Further judgment is made on the series arc based on the deep learning model, and the multi-cycle judgment array is recorded; S5. Determine whether to send a relay disconnect signal based on a multi-cycle judgment array.

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