DC arc fault detection and elimination circuit

Abstract

The utility model provides a direct current arc fault detection and elimination circuit, which is connected with a relay and 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] This utility model relates to the fields of DC circuit control, circuit fault detection and circuit safety, and in particular to a DC arc fault detection and elimination circuit. 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. Utility Model Content

[0008] To address the shortcomings of existing technologies, this utility model provides a DC arc fault detection and elimination circuit, specifically offering the following technical solution:

[0009] 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, 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 is composed 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, 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.

[0020] 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.

[0021] 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.

[0022] Preferably, the MCU processor module further includes a button switch circuit, which comprises a button switch S1 and a button switch S2:

[0023] 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.

[0024] 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.

[0025] Preferably, the relay switch driving module includes a relay driver chip U4;

[0026] 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.

[0027] Preferably, the process of the MCU processor driving the relay is as follows:

[0028] 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.

[0029] 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.

[0030] Compared with existing technologies, this solution has at least the following beneficial effects:

[0031] The high-precision DC current sampling circuit design provided in this solution achieves milliampere-level accuracy, reliable performance, simple structure, and cost savings.

[0032] This solution uses a magnetic latching relay. When the circuit power supply is interrupted, the state of the DC fault arc protection device remains unchanged. When the power supply is restored, the protector returns to its state before the power outage, thus ensuring no impact on the power consumption of connected equipment. Using a relay driver chip to control the on / off state of the power supply circuit results in a simple structure and cost-effectiveness.

[0033] 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

[0034] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a structural diagram of the DC arc fault detection and elimination circuit according to an embodiment of the present invention.

[0036] Figure 2 This is the power module circuit structure according to an embodiment of the present utility model;

[0037] Figure 3 The 5V to 3.3V power module structure of this invention is shown in this embodiment.

[0038] Figure 4 This is the microprocessor module circuit of an embodiment of the present utility model;

[0039] Figure 5 This is the circuit structure of the current signal acquisition and arc fault signal sampling module according to an embodiment of the present invention;

[0040] Figure 6 The relay drive and switch power supply circuit structure is shown in this embodiment of the utility model. Detailed Implementation

[0041] The technical solutions of the present utility model will be clearly and completely described below with reference to the figures in the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0042] The following section, using a specific embodiment, details the main circuit modules and detection methods of this solution. This solution mainly consists of four parts, combined with... Figure 1 As shown, these are the DC-DC switching power supply module, the main control MCU processor, the high-speed, high-precision DC current signal sampling module, and the relay switch drive module.

[0043] 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.

[0044] like 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.

[0045] The circuit structure of each part will be described in detail below.

[0046] 1. Switching power supply module

[0047] In this embodiment, the switching power supply module is designed as a high-voltage DC-DC conversion circuit, referencing... Figure 2 As shown, this module can accept a wide DC voltage input from 15V to 120V. The power supply is provided by a safety protection 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.

[0048] In the safety protection circuit, the varistor MOV1 is connected in parallel with the capacitor XC1, and then connected in series with the polarized capacitor C122 to ground. One end of the capacitor XC1 is connected to the positive terminal of the polarized capacitor C122, and the negative terminal of C122 is grounded. The other end of the 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 2. MCU processor module

[0054] In this embodiment, the core processor of the MCU processor module is a 32-bit MCU with AD conversion.

[0055] Combination Figure 3 As shown, 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 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 the PA0 pin. The sampled current signal is processed by the MCU's internal digital-to-analog conversion and then sent to the MCU processor. The MCU processor then determines whether a fault arc has occurred in the current loop, thereby determining whether to shut down the power supply.

[0056] This part of the hardware circuit also incorporates two push-button switches, S1 and S2, which can be manually switched on or off to turn the power supply on. The TEST manual switch here (i.e....) Figure 4 The main function of switch S1 is to transmit a fault arc signal in the current loop in an analog manner, and then this fault arc signal passes through the current sensor (i.e., Figure 5 The chip U1 in the sampled signal is input to the MCU. The MCU should detect the fault arc signal and drive the relay to cut off the power supply to ensure electrical safety. The function of the RESET button is: if the MCU detects no fault arc signal in the current sampling signal, the user 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 current circuit and ensure normal power supply.

[0057] 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:

[0058] 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.

[0059] 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 for the MCU to determine. In this embodiment, for example, the states can be set to 3: 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).

[0060] The analog voltage signal sent from the sampling circuit is connected to the PA0 pin of the MCU. This analog voltage signal is input to the PA0 pin of the MCU, and after the MCU's internal ADC converts the analog voltage signal sent from the sampling circuit into a digital signal, the MCU processes it and, after determining the arc signal, sends a Power_Off signal through PA7. Figure 3 The DR signal in the circuit drives the relay to turn off the power supply to the circuit. The PB1 pin of the MCU is connected to the relay driver chip U4, which outputs a Power_On signal. Figure 3 The R_DR signal in the circuit is used to drive the relay to turn on the power supply.

[0061] 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.

[0062] 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.

[0063] This embodiment uses a 20-pin MCU processor based on the ARM architecture and Cortex-4 core to meet the requirements for DC circuit fault arc diagnosis.

[0064] It should be further explained here that the MCU processor can drive the relay switch driver module based on the most basic threshold judgment or specific signal triggering of the on and off signals, or it can be based on complex logic judgment or neural network judgment. These simple or complex methods can be implemented by existing or well-known solutions. This part is not an improvement point of this solution and is well known to those skilled in the art. This part is not within the scope of discussion of this solution and will not be elaborated further.

[0065] 3. DC current signal sampling module

[0066] This 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, which is then sampled by the MCU via PA0 and converted 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, etc. This embodiment uses an 8-pin chip as an example.

[0067] 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 via 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 and AD converter are grounded through series capacitor C14.

[0068] 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 subsequent MCU unit can effectively detect arc fault signals.

[0069] 4. Relay switch driver module

[0070] See Figure 5As shown, the relay switch driver module uses U2 (i.e., the MCU processor) to control the relay driver chip U4, which controls the relay's on and off states. 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 relay driver chip U4 is connected to pin 1 of relay U7, and pin OB of relay driver chip U4 is connected to pin 6 of relay U7.

[0071] The specific driving process for the MCU to issue on / off signals is as follows:

[0072] 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.

[0073] 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.

[0074] In this embodiment, a magnetic latching relay is more preferably used, as it offers reliable performance.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; although the utility model 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 this utility model.

Claims

1. A direct current arc fault detection cancellation circuit, characterized by, The detection elimination circuit is connected with a relay, and the relay is connected with a load circuit, and the detection elimination 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 MCU processor is a 20-pin cortex-4 kernel MCU; 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 and converted into a digital signal through an internal AD converter of the MCU; the MCU processor module sends a control signal to the relay switch driving module based on the digital signal, and then controls the opening and closing actions of the relay to perform an arc fault elimination action on the load circuit; The switching power supply module is a high-voltage DCDC conversion circuit.

2. The detection cancellation circuit of claim 1, wherein, The direct current signal sampling module core adopts an 8-pin chip U1; An input pin 1 and a pin 2 of the chip U1 are connected with an input positive electrode of the direct current to be detected; a pin 3 and a pin 4 of the chip U1 are connected with a 4-pin L_OUT end of the relay U7; a VCC pin of the chip U1 is connected with a power supply VCC of the switching power supply module; a VIOUT pin of the chip U1 is connected with a resistor RF1 and a diode D1IN in series and then directly outputs to a PA0 port of the MCU processor; a FILTER pin of the chip U1 is connected with a ground through a capacitor CF; the resistor RF1 and the diode D1IN are connected with the ground through a series resistor R3; the diode D1IN is connected with the ground through a series capacitor C14.

3. The detection cancellation circuit of claim 1, wherein, The switching power supply module is connected with a DC wide voltage input through a safety protection circuit unit, outputs a low-voltage direct current and supplies power to multiple modules connected therewith; the switching power supply module core adopts a DCDC chip U3; The VIN pin of the 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 the chip U3; a resistor R3 is connected in series to the FB pin of the chip U3 and then grounded; a resistor R111 and an inductor L2 are connected in series to the CS pin of the chip U3 in sequence, and the resistor R111 is used as the positive pole of the output voltage; the negative pole of a Schottky diode D17 is connected in series to the VSS pin of the chip U3, the positive pole of the D17 is used as the negative pole of the output voltage; the negative pole of the D17 is connected between the resistor R111 and the inductor L2; a polarized capacitor C14333 is connected between the negative pole of the D17 and the inductor L2, wherein the positive pole of the C14333 is connected to the inductor L2; the polarized capacitor C14333 is also connected in parallel to a resistor R10; a resistor R2 and the negative pole of a Schottky diode D16 are connected in series to the VDD pin of the chip U3 in sequence, the positive pole of the D16 is connected to the positive pole of the output voltage, and the VDD pin of the chip U3 is connected to a capacitor C1422 and then 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 a resistor R4; the VDD pin of the chip U3 is connected to the resistor R111 and the inductor L2 through a capacitor C1422, and is also connected to the negative pole of the D17; the positive pole of the D17 is grounded and the negative pole of the polarized capacitor C14333 is grounded.

4. The detection cancellation circuit of claim 3, wherein, The safety protection circuit unit is composed of a pressure-sensitive resistor MOV1, a capacitor XC1 and a polarized capacitor C122; The pressure-sensitive resistor MOV1 is connected in parallel to the capacitor XC1, one end of the capacitor XC1 is connected to the positive pole of the polarized capacitor C122 and the positive pole of the input DC power supply, and the other end of the capacitor XC1 is connected to the negative pole of the input DC power supply; the negative pole of the capacitor C122 is grounded.

5. The detection cancellation circuit of claim 1, wherein, In the MCU processor module, the PA7 pin of the MCU processor sends a DR signal to drive the relay to cut off the power supply; the PB1 pin of the MCU processor sends a R_DR signal to drive the relay to turn on the power supply; The PA1 pin of the MCU processor is connected to the positive pole of the input DC power supply through a diode D14, a resistor R26, a transistor Q3, a diode D13 and parallel-connected resistors R4 and R6 in sequence; wherein the PA1 pin is connected to the positive pole of the diode D14, the negative pole of the diode D14 is connected to one end of the resistor R26, the other end of the resistor 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 pole of the diode D13, and the positive pole of the diode D13 is connected in series to the parallel-connected resistors R4 and R6; The crystal oscillator Y11 is connected between the PF0 pin and the PF1 pin of the MCU processor, and the two ends of the crystal oscillator Y11 are connected to the ground through a capacitor C8 and a capacitor C17 respectively.

6. The detection cancellation circuit of claim 1, wherein, The MCU processor module is also provided with a button switch circuit, and the button switch circuit comprises button switches S1 and S2. The button switch S1 is connected with the resistor R10 in series, the button switch S2 is connected with the resistor R9 in series, the two series circuits are connected in parallel, and the parallel circuit is connected with the capacitor C2 and the resistor R8 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, the button switch S1 and the button switch S2 is connected with the ground, and one end of the resistor R8, the resistor R9 and the resistor R10 is connected with the positive pole of the 5V-3.3V power module output voltage.

7. The detection cancellation circuit of claim 1, wherein, The MCU processor module further comprises a state indication circuit, the PA4 of the MCU processor is connected with the negative pole of the light emitting diode D6, the positive pole of the diode D6 is connected with the resistor R22 in series, and the positive pole of the 5V-3.3V power module output voltage is connected.

8. The detection cancellation circuit of claim 1, wherein, The relay switch driving module comprises a relay driving chip U4. The relay off signal is sent by the PA7 pin of the MCU processor and is connected with the IA pin of the relay driving chip U4; the relay on signal is sent by the PB1 pin of the MCU processor and is connected with the IB pin of the relay driving chip U4; the 1 pin of the relay driving chip U4 is connected with the 6 pin of the relay U7, and the 4 pin of the relay driving chip U4 is connected with the 1 pin of the relay U7; the OA pin of the relay driving chip U4 is connected with the 1 pin of the relay U7, and the OB pin of the relay driving chip U4 is connected with the 6 pin of the relay U7.

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