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

Abstract

The invention provides a direct current arc fault detection and elimination circuit and method, the circuit is connected with a relay, and the circuit comprises a switching power supply module, an MCU processor module, a direct current signal sampling module and a relay switch driving module; the direct current signal sampling module and the switching power supply module are powered by external direct current; the switching power supply module is connected with the MCU processor module, the direct current signal sampling module and the relay switch driving module; the direct current signal sampling module receives a current signal of a direct current circuit to be detected and outputs an analog voltage signal, and the analog voltage signal is transmitted to a PA0 port of the MCU processor; the AD conversion module in the MCU converts the analog voltage signal into a digital signal, and the MCU processor module sends a control signal to the relay switch driving module based on the digital signal. According to the scheme, high-voltage wide-voltage input is adopted, performance is stable, ripple waves are low, noise is low, the detection precision can reach the milliampere level, performance is reliable, the structure is simple, and cost is saved.

Description

Technical Field

[0001] The present invention relates to the fields of direct current circuit control, circuit fault detection and circuit safety, and in particular to a direct current arc fault detection and elimination circuit and a detection and elimination method. Background Art

[0002] Arc faults caused by problems such as the insulation performance of wires and cables can cause damage to power supply and distribution systems and electrical equipment. According to the nature of the power system where the arc fault occurs, it can be divided into AC arc faults and DC arc faults. Arc faults are often accompanied by sparks and high temperatures, which can cause further damage to the insulation of wires and cables, and even cause electrical fires.

[0003] The characteristics of DC arc faults are very different from those of AC arc faults: AC arc current is periodic and has a "zero rest zone" when crossing zero; while DC has no periodicity, no concept of fundamental wave, and has strong randomness and non-stationarity. Therefore, the general method of AC arc fault detection and detection and elimination circuit are not suitable for the detection of DC arc faults. In addition, since DC arcs do not have a zero crossing point, it is not easy to extinguish DC arcs. If they are not eliminated in time, arcing may occur for a long time, causing the fault to expand. Therefore, DC arc fault detection and elimination require more accuracy and speed.

[0004] The DC arc detection and elimination circuit commonly used in the prior art has certain problems:

[0005] For the power supply part, a DC-DC conversion power supply is used. A DC-DC low-voltage direct current power supply is simple and safe. If a high-voltage DC-DC direct current power supply is used, the implementation is complex and the noise interference is large.

[0006] DC current signal acquisition part: For DC with a range of more than ten amperes, a Hall current detection sensor is used, but the DC detection accuracy is insufficient and cannot reach the milliampere level.

[0007] In terms of eliminating circuit action drive, a multi-coil tripping mechanism is often used in the prior art. The tripping mechanism uses multiple coils, one for opening and one for closing, and has a position protection function, but the structure is generally complex. Summary of the invention

[0008] In view of the deficiencies of the prior art, the present invention provides a DC arc fault detection and elimination circuit and a detection and elimination method. Specifically, the present invention provides the following technical solutions:

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

[0010] The DC current signal sampling module and the switching power supply module are powered by external DC; 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 to be detected and outputs an analog voltage signal, which is transmitted to the PA0 port of the MCU processor and converted into a digital signal after passing through 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 actions of the relay to perform arc fault elimination actions on the load circuit;

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

[0013] Preferably, the core of the DC current signal sampling module adopts an 8-pin chip U1; it should be noted here 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] The input pins 1 and 2 of the chip U1 are connected to the positive electrode of the input DC current to be detected, and the pins 3 and 4 of the chip U1 are connected to the No. 4 pin L_OUT end of the relay U7; the VCC pin of the chip U1 is connected to the power supply VCC of the switching power module; the VIOUT pin of U1 is connected in series with the resistor RF1 and the diode D1IN, and then directly output to the PA0 end of the MCU processor; the FILTER pin of the chip U1 is grounded through the capacitor CF, the resistor RF1 and the diode D1IN are grounded through the series resistor R3, and the diode D1IN is grounded through the series capacitor C14.

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

[0016] The VIN pin of chip U3 is connected to the positive pole of the input DC power supply; a resistor R1 is connected in parallel between the VIN pin and the VDD pin 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 in sequence, and serves as the positive pole of the output voltage; the VSS pin of chip U3 is connected in series with the negative pole of Schottky diode D17, and the positive pole of D17 serves as the negative pole of the output voltage; the negative pole of D17 is connected between the resistor R111 and the inductor L2; the polarity capacitor C14333 is connected between the negative pole of D17 and the inductor L2, where C14333 The positive pole is connected to the inductor L2; the polarity capacitor C14333 is connected in parallel with the resistor R10; the VDD pin of the chip U3 is connected in series with the resistor and the negative pole of the Schottky diode D16 in sequence, the positive pole of D16 is connected to the positive pole of the output voltage, the VDD pin of the chip U3 is connected in series with a resistor and then connected to the positive pole of the input DC power supply; the FB pin of the chip U3 is connected to the positive pole of the output voltage through the resistor R4; the VDD pin of the chip U3 is connected between the resistor R111 and the inductor L2 through a capacitor C1422, and is connected to the negative pole of D17 at the same time; the positive pole of D17 is grounded and the negative pole of the polarity capacitor C14333 is grounded.

[0017] Preferably, the safety protection circuit unit is composed of a varistor MOV1, a capacitor XC1 and a polarity 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 electrode of the polarity capacitor C122 and the positive electrode of the input DC power supply. The other end of the capacitor XC1 is connected to the negative electrode of the input DC power supply. The negative electrode of the capacitor C122 is grounded.

[0019] Preferably, the switching power supply module adopts 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 circuit power supply; the PB1 pin of the MCU processor sends an R_DR signal to drive the relay to turn on the circuit power supply;

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

[0022] A crystal oscillator Y11 is connected between the PF0 pin and the PF1 pin of the MCU processor, and both ends of the crystal oscillator Y11 are grounded through capacitors C8 and C17 respectively.

[0023] Preferably, the MCU processor module is further provided with a button switch circuit, and the button switch circuit includes a button switch S1 and a button switch S2:

[0024] After the button switch S1 is connected in series with the resistor R10, and the button switch S2 is connected in series with the resistor R9, the two series circuits are connected in parallel and then connected in parallel with the circuit in which the capacitor C2 and the resistor R8 are connected in series; the NRST pin of the MCU processor is connected between the capacitor C2 and the resistor R8, the PA2 pin of the MCU processor is connected between the button switch S2 and the resistor R9, and the PA3 pin of the MCU processor is connected between the button switch S1 and the resistor R10; one end of the capacitor C2 connected to the button switch S1 and the button switch S2 is commonly grounded, and one end of the resistors R8, R9 and R10 is commonly connected to the positive electrode of the output voltage of the 5V to 3.3V power supply module.

[0025] Preferably, the MCU processor module also includes a status indication circuit, wherein PA4 of the MCU processor is connected to the cathode of the light-emitting diode D6, and the anode of the diode D6 is connected in series with a resistor R22 and then connected to the anode of the output voltage of the 5V to 3.3V power supply module;

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

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

[0028] The relay closing signal is sent by the PA7 pin of the MCU processor and connected to the IA pin of the relay driver chip U4; the relay opening signal is sent by the PB1 pin of the MCU processor and connected to the IB pin 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; and 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, the DR signal is output to the IA pin of the relay driver chip U4 through the PA7 pin of the MCU processor, and then the OA pin of the relay driver chip U4 outputs a high level to drive the relay U7 to turn off;

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

[0032] On the other hand, the present invention further provides a DC arc fault detection and elimination method, which is applied to the DC arc fault detection and elimination circuit as described above, and the method comprises:

[0033] S1, preprocessing the frequency domain current signal obtained by the DC current signal sampling module, and then performing smoothing filtering;

[0034] S2, extracting features from the smoothed 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 decoupling signal; if it is a series arc, proceed to step S4;

[0036] S4, further judging the series arc based on the deep learning model, and recording a multi-cycle judgment array;

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

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

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

[0040] This solution uses a magnetic latching relay. When the circuit power is off or the power is off, the state of the DC fault arc protection device will not change. When the power is restored, the protector will return to the state before the power outage, so that the power consumption of the connected equipment will not be affected. The relay driver chip and relay are used to realize the on and off control of the power supply circuit, which has a simple structure and saves costs.

[0041] This solution adopts high voltage input, wide voltage input DCDC voltage conversion, stable performance, low ripple, low noise, and can provide high-quality power supply to each MCU on the PCBA. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

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

[0045] Figure 3 The 5V to 3.3V power module structure of the embodiment of the present invention;

[0046] Figure 4 A microprocessor module circuit according to an embodiment of the present invention;

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

[0048] Figure 6 The relay driving and switch power supply circuit structure of the embodiment of the present invention;

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

[0050] Figure 8 The flowchart of the arc fault diagnosis method according to the embodiment of the present invention is shown in FIG. DETAILED DESCRIPTION

[0051] The following will be combined with the figures in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0053] In addition, it also includes a relay used in conjunction with it, and a load circuit controlled by the relay. Among them, the DC current signal sampling module and the switching power supply module are powered by external DC; the switching power supply module is connected to the MCU processor, the DC current signal sampling module and the relay switch drive module to provide a stable power supply for the operation of each module circuit; the DC current signal sampling module transmits the sampling signal to the MCU processor, and the MCU processor sends a control signal to the relay switch drive module, which further controls the opening and closing actions of the relay to perform arc fault elimination actions on the load circuit.

[0054] like Figure 1 A DC current sampling circuit, a relay switch drive circuit and a relay are added between the power supply DC and the load. The relay receives a signal from the MCU to drive 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 is determined whether there is an arc fault, and then a signal is sent to the relay switch drive module. The relay switch drive circuit sends an on / off command to the relay to determine whether to connect or shut down the load circuit.

[0055] The following is a detailed description of the circuit structure of each part.

[0056] 1. Switching power supply module

[0057] In this embodiment, the switching power supply module is designed as a high-voltage DCDC conversion circuit. Figure 2 As shown, this module can receive a wide voltage input of 15V to 120V DC. The power supply passes through the safety protection circuit composed of varistor MOV1, capacitor XC1, and polar capacitor C122, and obtains low-voltage 5V or 3V DC power supply through DC-DC chip U3 and peripheral circuits to power other electronic devices on the PCB. Here, the U3 chip can be a DCDC chip such as H6253C.

[0058] In the safety protection circuit, the varistor MOV1 is connected in parallel with the capacitor XC1, and then connected in parallel with the polar capacitor C122 to ground, one end of the capacitor XC1 is connected to the positive electrode of the polar capacitor C122, the negative electrode of C122 is grounded, and the other end N_OUT of the capacitor XC1 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-pole (i.e., negative electrode) output end of the charging protection circuit (i.e., PCBA), and directly connected to the N-pole (i.e., negative electrode) input end of the rechargeable battery.

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

[0060] The switching power supply module proposed in this scheme uses a DC-DC chip to connect the matching circuit to achieve good wide voltage input processing and compatibility, adapt to a wide DC input voltage range, and is suitable for DCDC conversion of different DC voltage ranges. The biggest technical advantage of this switching power supply module is that it uses professional ASIC to quickly respond to the input DC fluctuation voltage. Even if the input voltage fluctuates from 15V to 96V, the power chip can adapt to this voltage change and ensure the output of stable 5V and 3.3V DC constant voltage. When performing voltage conversion, this switching power supply module achieves the following through energy integration:

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

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

[0063] 2. MCU processor module

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

[0065] Combination Figure 3 As shown, the current sensor inputs the sampled current analog signal into the MCU through the PA0 interface of the MCU. The MCU uses an internal 32-bit AD converter to convert the analog continuous current signal into a digital intermittent signal. The main purpose of using 32-bit AD conversion is to improve the accuracy of analog-to-digital conversion and to obtain the precise current signal value as accurately as possible so that the MCU can accurately detect the fault arc current characteristic signal contained in the circuit current. The MCU obtains the current signal through pin PA0 and after digital-to-analog conversion, it first passes through the neural network deep learning model and multi-feature fusion rule algorithm contained in the MCU embedded program for performance analysis and calculation, and then determines whether a fault arc occurs in the current loop, thereby determining whether to shut down the power supply.

[0066] This part of the hardware circuit is designed with two push button switches, namely S1 and S2, which can manually turn off or on the power supply. The TEST manual switch (i.e. Figure 4 The main function of the S1 switch in the circuit is to carry a fault arc signal on the current loop in an analog manner, and then the fault arc signal passes through the current sensor (i.e. Figure 5 The chip U1 in the circuit is sampled and input into the MCU. The MCU should determine the fault arc signal, thereby driving the relay to cut off the power supply to ensure power safety. The function of the RESET button is: if the MCU detects that there is no fault arc signal in the current sampling signal, you can manually press the RESET button (i.e. Figure 4 The S2 switch in the circuit can close the relay through the MCU to restore the normal power supply of the current loop.

[0067] S1 and S2 correspond to the two buttons on the shell, which are used to switch the circuit and also to test whether the system works normally. When S1 is pressed, it is the Off_Key signal, corresponding to PA7 sending the Power_Off signal, and the circuit is turned off. When S2 is pressed, it is the On_Key signal, corresponding to PB1's Power_On signal, and the circuit is turned on. That is, the manual key press and the AD sampling automatically send out the switch signal to achieve the same effect. The circuit design of this part is as follows:

[0068] S1 is connected in series with resistor R10, and after S2 is connected in series with resistor R9, the two lines are connected in parallel, and then connected in parallel with the line in series with capacitor C2 and resistor R8; the NRST pin of the MCU is connected between capacitor C2 and resistor R8, pin PA2 is connected between S2 and resistor R9, and pin PA3 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 pole of the 5V to 3.3V power supply module of the circuit board.

[0069] The path from PA4 of MCU to light-emitting diode D6 is used as an indicator light. Its main function is to indicate different states of the current loop determined by MCU. In this embodiment, the states can be set to 3: State 1: normal power supply state (relay closed), or the line restores normal power supply; State 2: there is a fault arc state in the line (relay disconnected), State 3: the fault arc of the line has been eliminated (relay disconnected).

[0070] The PA0 pin of the MCU is connected to the analog voltage signal sent by the sampling circuit. The analog voltage signal is input to the PA0 pin of the MCU. After the ADC inside the MCU converts the analog voltage signal sent by the sampling circuit into a digital signal through the A / D inside the MCU, the MCU processes it and determines the arc signal. Then the MCU sends a Power_Off signal through PA7, that is, Figure 3 The DR signal in the circuit drives the relay to shut down the circuit power supply. The PB1 terminal of the MCU is connected to the relay driver chip U4, which sends out the Power_On signal, that is, Figure 3 The R_DR signal in the circuit is used to drive the relay to turn on the circuit power supply.

[0071] The PA1 pin of the MCU is connected to the positive electrode of the input power supply IN_L through the diode D14, the resistor R26, the transistor Q3, the diode D13 and the parallel resistors R4 and R6 in sequence. Among them, PA1 is connected to the positive electrode of D14, the negative electrode of D14 is connected to one end of the resistor R26, the other end of R26 is connected to the base of the transistor Q3, the emitter of Q3 is grounded, the collector of Q3 is connected to the negative electrode of the diode D13, and the positive electrode of D13 is connected in series with the parallel R4 and R6.

[0072] The crystal oscillator Y11 is connected between the PF0 pin and the PF1 pin of the MCU, and both ends of the 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 the 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 constraints, it is very critical to determine an intelligent algorithm chip suitable for DC circuit fault arc diagnosis. Chips that meet the computing power requirements cannot be used due to their large number of pins, large size, and high cost, while most chips that meet the requirements of the product are insufficient in computing power, resulting in delayed and incorrect judgments of thermal DC circuit fault arcs. This embodiment uses a 20-pin MCU based on the arm architecture cortex-4 core to meet the requirements of DC circuit fault arc diagnosis.

[0075] Combination Figure 6 , Figure 7 As shown, arc fault detection is mainly divided into four stages:

[0076] (1) In the current signal sampling stage, the battery circuit current analog signal sampling is realized; the current signal of the battery pack is passed through the transformer and then the analog signal sampling is performed;

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

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

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

[0080] Further preferably, the process of feature extraction and fault diagnosis through the network model is as follows:

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

[0082] (2) Extracting features from the smoothed 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, enter the final judgment and send a relay decoupling signal; if it is a series arc, enter the next step;

[0084] (4) Further judge the series arc based on the deep learning model and record the multi-cycle judgment array;

[0085] (5) Determine whether to send a relay decoupling signal based on a multi-cycle judgment array. Furthermore, the multi-cycle can sample, for example, 8 current half-cycles (10ms per cycle, 5ms for a half cycle), and the neural network performs an operation once per half cycle, i.e., makes 8 judgments. If multiple outputs out of the 8 times are "faults" (e.g., 5 or 6 times), it is considered that there is an arc fault in the current, and the MCU outputs a decoupling command, i.e., the PA7 pin of the MCU issues a DR command to decouple; the use of multi-cycle operations can effectively reduce the probability of false operations.

[0086] Here, it needs to be further explained that for a specific network model, an existing model in the prior art can be used to train the network model through the type of fault arc and the corresponding current characteristic historical data. This part is not within the scope of discussion of this solution and will not be repeated.

[0087] 3. DC current signal sampling module

[0088] The circuit module structure design reference Figure 4 As shown, the analog voltage signal formed after sampling is sent to the PA0 port of the MCU processor; the sampling part samples the current signal, and the MCU performs A / D conversion through PA0 to convert it into a digital signal for 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. This embodiment takes an 8-pin chip as an example.

[0089] Input pins 1 and 2 of chip U1 are connected to input current IN_L (i.e., positive pole). Here, the input circuit is also the current of the DC power supply to be detected. Pins 3 and 4 of U1 are connected to pin 4 of relay U7, i.e., L_OUT terminal of U7. The outputs of these two pins are 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, and the resistor RF1 and diode D1IN are grounded through series resistor R3, and the diode D1IN is grounded through series capacitor C14.

[0090] The circuit module U1 and the AD converter inside the MCU work together to achieve high-precision current signal sampling to ensure that the MCU unit effectively detects arc fault signals.

[0091] 4. Relay switch driver module

[0092] See also Figure 5 As shown, the relay switch drive module uses U2 (i.e., MCU processor) to control the relay driver chip U4, and the relay is controlled to be on and off through the relay driver chip U4. The chip U4 can be selected from, for example, CN8023 chip. Among them, the relay off signal is sent by the pin PA7 of the MCU processor and connected to the IA pin (i.e., pin 3) of the relay driver chip U4; the relay on signal is sent by the PB1 pin of the MCU processor and connected to the IB pin (i.e., pin 6) of the relay driver chip U4. Pin 1 of U4 is connected to pin 6 of the relay U7, and pin 4 of 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; and pin OB of the relay driver chip U4 is connected to pin 6 of the relay U7.

[0093] The specific driving process of MCU sending on and off signals is as follows:

[0094] When the MCU sends an off signal, the DR signal is output through the PA7 pin of the MCU processor to the No. 3 pin IA of the relay driver chip U4, and then the No. 4 pin OA of the relay driver chip U4 outputs a high level to drive the relay U7 to turn off.

[0095] When the MCU sends an open signal, the PB1 pin of the MCU processor outputs the R_DR signal to the No. 6 pin IB of the relay driver chip U4, and then the No. 1 pin OB of the relay driver chip U4 outputs a high level to drive the relay U7 to connect the circuit.

[0096] In this embodiment, it is more preferred to use a magnetic latching relay with reliable performance.

[0097] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing related hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions 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, the relay is connected to a load circuit, and the detection elimination circuit comprises: 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 external DC; 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 to be detected and outputs an analog voltage signal, which is input to the PA0 port of the MCU processor and converted into a digital signal after passing through 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 actions of the relay to perform arc fault elimination actions on the load circuit; The switching power supply module is a high-voltage DCDC 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; The input pins 1 and 2 of the chip U1 are connected to the positive electrode of the input DC current to be detected, and the pins 3 and 4 of the chip U1 are connected to the L_OUT end of pin 4 of the relay U7; the VCC pin of the chip U1 is connected to the power supply VCC of the switching power module; the VIOUT pin of U1 is connected in series with the resistor RF1 and the diode D1IN, and then directly output to the PA0 end of the MCU processor; the FILTER pin of the chip U1 is grounded through the capacitor CF, the resistor RF1 and the diode D1IN are grounded through the series resistor R3, and the diode D1IN is grounded through the series capacitor C14.

3. The detection elimination circuit according to claim 1, characterized in that: The switching power supply module is connected to a DC wide voltage input through a safety protection circuit unit, and outputs a low voltage DC to power multiple modules connected thereto; the core of the switching power supply module adopts a DCDC chip U3; The VIN pin of chip U3 is connected to the positive pole of the input DC power supply; a resistor R1 is connected in parallel between the VIN pin and the VDD pin 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 in sequence, and serves as the positive pole of the output voltage; the VSS pin of chip U3 is connected in series with the negative pole of Schottky diode D17, and the positive pole of D17 serves as the negative pole of the output voltage; the negative pole of D17 is connected between the resistor R111 and the inductor L2; the polar capacitor C14333 is connected between the negative pole of D17 and the inductor L2, and the positive pole of C14333 is connected to Inductor L2; polarity 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 electrode of Schottky diode D16 in sequence, the positive electrode of D16 is connected to the positive electrode of the output voltage, the VDD pin of chip U3 is connected in series with a capacitor C1422 and then connected to the positive electrode of the input DC power supply; the FB pin of chip U3 is connected to the positive electrode of the output voltage through resistor R4; the VDD pin of chip U3 is connected between resistor R111 and inductor L2 through a capacitor C1422, and is connected to the negative electrode of D17 at the same time; the positive electrode of D17 is grounded and the negative electrode of polarity capacitor C14333 is grounded.

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

5. The detection elimination circuit according to claim 3, characterized in that: The switching power supply module adopts 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 circuit power supply; the PB1 pin of the MCU processor sends an R_DR signal to drive the relay to turn on the circuit power supply; The PA1 pin of the MCU processor is connected to the positive electrode of the input DC power supply through the diode D14, the resistor R26, the transistor Q3, the diode D13 and the parallel resistors R4 and R6 in sequence; wherein the PA1 pin is connected to the positive electrode of the diode D14, the negative electrode of the diode D14 is connected to one end of the resistor R26, the other end of R26 is connected to the base of the transistor Q3, the emitter of the transistor Q3 is grounded, the collector of the transistor Q3 is connected to the negative electrode of the diode D13, and the positive electrode of the diode D13 is connected in series with the parallel R4 and R6; A crystal oscillator Y11 is connected between the PF0 pin and the PF1 pin of the MCU processor, and both ends of the crystal oscillator Y11 are grounded through capacitors C8 and C17 respectively.

7. The detection elimination circuit according to claim 1, characterized in that: The MCU processor module is also provided with a button switch circuit, and the button switch circuit includes a button switch S1 and a button switch S2: After the button switch S1 is connected in series with the resistor R10, and the button switch S2 is connected in series with the resistor R9, the two series circuits are connected in parallel and then connected in parallel with the circuit in which the capacitor C2 and the resistor R8 are connected in series; the NRST pin of the MCU processor is connected between the capacitor C2 and the resistor R8, the PA2 pin of the MCU processor is connected between the button switch S2 and the resistor R9, and the PA3 pin of the MCU processor is connected between the button switch S1 and the resistor R10; one end of the capacitor C2 connected to the button switch S1 and the button switch S2 is commonly grounded, and one end of the resistors R8, R9 and R10 is commonly connected to the positive electrode of the output voltage of the 5V to 3.3V power supply module.

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 cathode of the light-emitting diode D6, and the anode of the diode D6 is connected in series with a resistor R22 and then connected to the anode of the output voltage of the 5V to 3.3V power supply module; The status indication circuit is set to three states: state 1, normal power supply state or the line restores normal power supply; state 2, there is a fault arc in the line; state 3, the line fault arc has been eliminated.

9. The detection elimination circuit according to claim 1, characterized in that: The relay switch driving module includes a relay driving chip U4; The relay closing signal is sent by the PA7 pin of the MCU processor and connected to the IA pin of the relay driver chip U4; the relay opening signal is sent by the PB1 pin of the MCU processor and connected to the IB pin 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; and pin OB of the relay driver chip U4 is connected to pin 6 of the relay U7.

10. A method for detecting and eliminating a DC arc fault, characterized in that: The method is applied to the DC arc fault detection and elimination circuit according to any one of claims 1 to 9, and the method comprises: S1, preprocessing the frequency domain current signal obtained by the DC current signal sampling module, and then performing smoothing filtering; S2, extracting features from the smoothed 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 decoupling signal; if it is a series arc, proceed to step S4; S4, further judging the series arc based on the deep learning model, and recording a multi-cycle judgment array; S5. Determine whether to send a relay decoupling signal based on a multi-cycle judgment array.

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