Arc detection circuit, device and method with automatic detection function

Abstract

The application discloses an arc detection circuit with automatic detection function, an arc detection device and an arc detection method. The arc detection circuit comprises an automatic detection circuit, a signal sampling and amplification circuit, a filter circuit, a proportional amplification circuit and a power supply circuit which are electrically connected with each other. The port 1 of a current transformer CT1 in the automatic detection circuit is connected with a current output end of a line to be detected, and the port 3 is connected with a current input end of the line. After the automatic detection circuit receives an external input DSP signal, the circuit is turned on, the current transformer CT1 starts to extract an alternating current part in the current output by the line, and the alternating current part is sequentially subjected to the amplification-filtering-amplification treatment of the signal sampling and amplification circuit, the filter circuit and the proportional amplification circuit, and then is output to an externally connected DSP processor to further analyze the arc fault of the line. The arc detection circuit provided by the application is used in cooperation with the DSP processor to realize the automatic arc detection, and the automation degree of the arc detection is improved.

Description

Technical Field

[0001] This invention relates to the field of arc fault detection technology, and specifically to an arc detection circuit, device, and detection method with automatic detection function. Background Technology

[0002] The basic function of switching devices is to separate circuits within a required time, i.e., their switching action. Mechanical switching devices use contacts to interrupt circuit current. When interrupting a circuit in the atmosphere, if the voltage exceeds 12-20V and the interrupted current exceeds 0.25-1A, a ball of extremely hot, brightly lit, and conductive gas, approximately cylindrical in shape, is usually generated in the contact gap (also called the arc gap). This is an electric arc. The occurrence of an electric arc can damage equipment, or even cause explosions and fires, threatening life and property. Therefore, timely detection of electric arc phenomena is crucial to avoiding the hazards of electric arcs and ensuring that electrical equipment is not damaged. However, existing electric arc detection devices generally do not have self-testing functions, requiring manual switching on or off, or keeping the device in a constant detection state. Manual switching is cumbersome, and constantly keeping the device in a detection state increases the probability of malfunction due to prolonged operation, and is also detrimental to energy conservation and emission reduction. Summary of the Invention

[0003] The present invention aims to achieve automatic arc detection and reduce the probability of arc detection device failure, and provides an arc detection circuit, device and detection method with automatic detection function.

[0004] To achieve this objective, the present invention adopts the following technical solution:

[0005] An arc detection circuit with automatic detection function is provided, comprising an automatic detection circuit, a signal sampling amplification circuit, a filtering circuit, a proportional amplification circuit, and a power supply circuit for each circuit, all electrically connected to each other. The first port of the current transformer CT1 in the automatic detection circuit is connected to the current output terminal of the line to be detected for arc faults, and the third port is connected to the current input terminal of the line. After receiving an externally input DSP signal, the automatic detection circuit is activated. The current transformer CT1 extracts abrupt changes in the AC component of the current output from the line according to the fixed frequency and harmonic frequencies of the DSP signal. These amplified, filtered, and amplified AC signal is then sequentially processed by the signal sampling amplification circuit, the filtering circuit, and the proportional amplification circuit before being output to an externally connected DSP processor for further arc fault analysis of the line.

[0006] Preferably, the automatic detection circuit includes the current transformer CT1, transistor Q1, resistors R3, R4, R5, and capacitor C9. One end of resistor R4 serves as the input terminal of the DSP signal, connected to the DSP signal output terminal of the DSP processor, and the other end is connected to the base of transistor Q1. Resistor R5 is connected between the base and emitter of transistor Q1, and the emitter of transistor Q1 is grounded. Capacitor C9 is connected in parallel across resistor R5. One end of resistor R3 is connected to the collector of transistor Q1, and the other end is connected to the fourth port of current transformer CT1. The fourth port of current transformer CT1 is also connected to the first electrical input terminal (100) of the signal sampling amplification circuit, and the third port is connected to the second electrical input terminal (200) of the signal sampling amplification circuit and to the 2.5V voltage output terminal VREF of the power supply circuit.

[0007] Preferably, the signal sampling amplification circuit includes rectifiers D1 and D2, amplifier U2A, resistors R6, R7, R9, R10, R11, R25, R26, R27, and capacitors C14, C15, and C21. The non-inverting input terminal of amplifier U2A is connected in series with resistor R6 to serve as the first signal input terminal (100) of the signal sampling amplification circuit, and the inverting input terminal is connected in series with resistor R26 to serve as the second signal input terminal (200) of the signal sampling amplification circuit.

[0008] The resistor R27 is connected between the inverting input terminal and the output terminal of the amplifier U2A; the resistors R10 and R11 connected in parallel are connected in series with the rectifier D2, one end of the resistors R10 and R11 connected in series is connected to the non-inverting input terminal of the amplifier U2A, and the other end is connected in series with the rectifier D2 and the resistor R26 and then connected to the inverting input terminal of the amplifier U2A.

[0009] One end of the capacitors C14 and C15 connected in parallel is connected to the non-inverting input terminal of the amplifier U2A, and the other end is connected in series with the resistor R26 and then connected to the inverting input terminal of the amplifier U2A.

[0010] One end of the resistors R9 and R25, which are connected in series, is connected in series with resistor R6 and then connected to the non-inverting input terminal of amplifier U2A; the other end is connected in series with resistor R26 and then connected to the inverting input terminal of amplifier U2A.

[0011] The rectifier D1 is connected in parallel between the resistors R9 and R25, which are connected in series.

[0012] The output terminal of the amplifier U2A is connected in series with the resistor R7 and then serves as the signal output terminal of the signal sampling amplification circuit, which is connected to the input terminal of the filter circuit; the power input terminal of the amplifier U2A is connected to the 5V voltage output terminal +5VARC of the power supply circuit, and the ground terminal is grounded.

[0013] One end of the capacitor C21 is connected in series with the resistor R26 and then connected to the inverting input terminal of the amplifier U2A and the 2.5V voltage output terminal VREF of the power supply circuit.

[0014] Preferably, the filtering circuit includes a first high-pass filter circuit, which includes an amplifier U3B, resistors R15, R16, R17, R8, C19, and C20. One end of the capacitor C20 serves as the input terminal of the first high-pass filter circuit and is connected to the signal output terminal of the signal sampling amplification circuit. The other end is connected in series with the capacitor C19 and then connected to the non-inverting input terminal of the amplifier U3B.

[0015] One end of the resistors R15 and R16 connected in parallel is connected to the inverting input terminal of the amplifier U3B, and the other end is connected in series with the capacitor C19 and then connected to the non-inverting input terminal of the amplifier U3B.

[0016] One end of the resistor R17 is connected to the non-inverting input terminal of the amplifier U3B, and the other end is connected in series with the resistor R8 and then connected to the 2.5V voltage output terminal VREF of the power supply circuit.

[0017] The output terminal of the amplifier U3B is connected to its inverting input terminal and serves as the signal output terminal of the first high-pass filter circuit.

[0018] Preferably, the filtering circuit further includes a second high-pass filter circuit, which includes an amplifier U3A, capacitors C18 and C17, and resistors R12, R13, R14, and R19. The non-inverting input terminal of the amplifier U3A is connected to the capacitors C17 and C18 in sequence and then connected to the signal output terminal of the first high-pass filter circuit.

[0019] One end of the resistors R12 and R13 connected in parallel is connected to the inverting input terminal of the amplifier U3A, and the other end is connected in series with the capacitor C17 and then connected to the non-inverting input terminal of the amplifier U3A.

[0020] One end of the resistor R19 is connected to the non-inverting input terminal of the amplifier U3A, and the other end is connected in series with the resistor R14 and then connected to the 2.5V voltage output terminal VREF of the power supply circuit.

[0021] The power input terminal of the amplifier U3A is connected to the 5V voltage output terminal +5VARC of the power supply circuit, and the ground terminal is grounded.

[0022] The output terminal of the amplifier U3A is connected to its inverting input terminal and serves as the signal output terminal of the second high-pass filter circuit.

[0023] Preferably, the filtering circuit further includes a first low-pass filter circuit, which includes an amplifier U4A, capacitors C13 and C16, and resistors R21, R22, R23, and R24. The non-inverting input terminal of the amplifier U4A is connected in series with the resistors R24, R23, R22, and R21 and then connected to the signal output terminal of the second high-pass filter circuit. The inverting input terminal is connected in series with the capacitor C13 and the resistors R23 and R24 and then connected to its non-inverting input terminal.

[0024] One end of the capacitor C16 is connected to the non-inverting input terminal of the amplifier U4A, and the other end is connected to the 2.5V voltage output terminal VREF of the power supply circuit.

[0025] The inverting input of the amplifier U4A is also connected to its output. The power input is connected to the 5V voltage output +5VARC of the power supply circuit. The grounding terminal is grounded, and the output terminal serves as the signal output of the first low-pass filter circuit.

[0026] Preferably, the filtering circuit further includes a second low-pass filter circuit, which includes an amplifier U2B, resistors R20, R18, C10, C11, and C12. The non-inverting input terminal of the amplifier U2B is connected in series with the resistors R18 and R20 and then connected to the signal output terminal of the first low-pass filter circuit. The inverting input terminal is connected in series with the capacitor C10 and the resistor R18 and then connected to its own non-inverting input terminal.

[0027] One end of the capacitors C11 and C12, which are connected in parallel with each other, is connected to the non-inverting input terminal of the amplifier U2B, and the other end is connected to the 2.5V voltage output terminal VREF of the power supply circuit.

[0028] The inverting input of the amplifier U2B is also connected to its output, which serves as the signal output of the second low-pass filter circuit.

[0029] Preferably, the proportional amplifier circuit includes amplifier U4B, capacitor C24, resistors R28, R29, R30, R31, R32 and capacitor C25. The non-inverting input terminal of amplifier U4B is connected in series with resistor R32 and then connected to the signal output terminal of the filter circuit. The inverting input terminal is connected in series with resistor R30 and then grounded.

[0030] The capacitor C24 is connected between the inverting input terminal and the output terminal of the amplifier U4B; one end of the resistor R28 is connected to the output terminal of the amplifier U4B, and the other end is connected in series with the resistors R29 and R30 and then grounded. The resistors R28 and R29, which are connected in series, are connected between the output terminal and the inverting input terminal of the amplifier U4B.

[0031] The output of the amplifier U4B is connected in series with the resistor R31 and then connected to the ARC-AD port of the DSP processor to transmit the acquired arc signal to the DSP processor.

[0032] One end of the capacitor C25 is connected in series with the resistor R31 and then connected to the output terminal of the U4B, while the other end is grounded.

[0033] Preferably, the power supply circuit includes an inductor L1, a voltage regulator U1, capacitors C1-C8, and resistors R1 and R2. One end of the inductor L1 is connected to an external 5V power supply and is connected in series with capacitors C3 and C2 to the other end of the circuit, which serves as the 5V voltage output terminal +5VARC of the power supply circuit. Capacitor C4 is connected in parallel across capacitor C3, and capacitor C1 is connected in parallel across capacitor C2.

[0034] One end of the resistor R1 is connected to the 5V voltage output terminal +5VARC of the power supply circuit, and the other end is connected to pin (2) of the voltage regulator U1. Pin (3) of the voltage regulator U1 is grounded, and pin (1) is connected to one end of the resistor R2. The other end of the resistor R2 is connected to the 5V voltage output terminal +5VARC.

[0035] The capacitor C5 is connected in parallel across the resistor R2;

[0036] The capacitor C6 is connected in parallel across the two ends of the capacitor C5;

[0037] The capacitor C7 is connected between pin (2) and pin (3) of the voltage regulator U1;

[0038] The capacitor C8 is connected in parallel across the two ends of the capacitor C7;

[0039] The pin (2) of the voltage regulator U1 is connected to the intersection point A of the pin (1) of the voltage regulator U1 and the resistor R2. The intersection point A is connected to the intersection point B of the capacitor C5 and the capacitor C7. The intersection point B is connected to the intersection point C of the capacitor C6 and the capacitor C8. The intersection point C serves as the 2.5V voltage output terminal VREF of the power supply circuit.

[0040] The present invention also provides an arc detection device, wherein the arc detection device is provided with the aforementioned arc detection circuit with automatic detection function.

[0041] The present invention also provides an arc detection method, the steps of which include:

[0042] S1, the automatic detection circuit in the arc detection circuit with automatic detection function loads the DSP signal received by the external DSP processor onto the current transformer CT1.

[0043] S2, after the current transformer CT1 is loaded with the DSP signal, it extracts the AC component of the current output from the line it is connected to according to the fixed frequency and harmonic frequency of the DSP signal and inputs it to the signal sampling and amplification circuit in the arc detection circuit for signal amplification processing before output.

[0044] S3, the filtering circuit in the arc detection circuit filters the current signal after signal amplification and outputs it;

[0045] S4, the proportional amplifier circuit in the arc detection circuit performs signal proportional amplification processing on the filtered current signal and outputs it to the DSP processor;

[0046] S5, the DSP processor analyzes whether an arc fault has occurred in the line based on the received current signal and outputs the analysis result.

[0047] The arc detection circuit provided by this invention, when used in conjunction with a DSP processor, enables automatic arc detection of the object to be detected, thereby improving the automation level of arc detection and reducing the probability of damage to existing arc detection devices due to prolonged operation. Attached Figure Description

[0048] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0049] Figure 1 This is a circuit structure diagram of the automatic detection circuit in an arc detection circuit with automatic detection function provided in an embodiment of the present invention;

[0050] Figure 2 This is a diagram showing the interconnection between the signal sampling and amplification circuit, the first high-pass filter circuit, and the second high-pass filter circuit in the arc detection circuit.

[0051] Figure 3 This is a diagram showing the interconnection between the first low-pass filter circuit, the second low-pass filter circuit, and the proportional amplifier circuit in the arc detection circuit.

[0052] Figure 4 This is a circuit diagram of the power supply circuit in the arc detection circuit;

[0053] Figure 5 This is a diagram illustrating the implementation steps of an arc detection method provided in an embodiment of the present invention;

[0054] Figure 6 It is an AC spectrum collected when no electric arc occurs in the object being tested;

[0055] Figure 7 It is an AC spectrum image collected when the object being tested generates an electric arc. Detailed Implementation

[0056] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0057] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0058] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0059] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0060] This invention provides an arc detection circuit with automatic detection function, comprising electrically connected components such as... Figure 1 The automatic detection circuit shown, such as Figure 2 The signal sampling and amplification circuit 10 shown is shown. Figure 2 and Figure 3 The filter circuit shown includes a first high-pass filter circuit labeled "20", a second high-pass filter circuit labeled "30", a first low-pass filter circuit labeled "40", and a second low-pass filter circuit labeled "50". Figure 3 The proportional amplifier circuit 60 shown, and the power supply for each circuit, are as follows: Figure 4 The power supply circuit shown is as follows. Figure 1 As shown, in the automatic detection circuit, port 1 of the current transformer CT1 is connected to the current output terminal of the line to be detected for arcing, and port 3 is connected to the current input terminal of the line; the automatic detection circuit is turned on after receiving the externally input DSP signal. Figure 1 The “TEST” in the text represents the input DSP signal, preferably a square wave with a frequency of 3kHz. Upon receiving this square wave, transistor Q1 turns on, and the square wave is superimposed on current transformer CT1. The automatic detection circuit can then detect a series of AC component abrupt changes in the output current of the line (such as 3kHz and its harmonics 6kHz, 9kHz, 12kHz, etc.). Current transformer CT1 extracts the AC component abrupt changes in the output current of the line according to the fixed frequency of the DSP signal and its harmonic frequencies. After sequential AC signal amplification-filtering-amplification processing by signal sampling amplification circuit, filtering circuit, and proportional amplification circuit, the signal is output to the externally connected DSP processor for further arc fault analysis of the line.

[0061] The structure of each component circuit in the arc detection circuit is explained in detail below:

[0062] like Figure 1 As shown, the automatic detection circuit includes a current transformer CT1, a transistor Q1, resistors R3, R4, R5, and a capacitor C9. One end of resistor R4 serves as the input terminal of the DSP signal, connected to the DSP signal output terminal of the DSP processor, and the other end is connected to the base of transistor Q1. Resistor R5 is connected between the base and emitter of transistor Q1, and the emitter of transistor Q1 is grounded. Capacitor C9 is connected in parallel across resistor R5. One end of resistor R3 is connected to the collector of transistor Q1, and the other end is connected to port 4 of current transformer CT1. Port 4 of current transformer CT1 is also connected to the first electrical input terminal 100 of the signal sampling amplifier circuit, and port 3 is connected to the second electrical input terminal 200 of the signal sampling amplifier circuit and to the 2.5V voltage output terminal VREF of the power supply circuit.

[0063] The principle behind the automatic arc detection circuit is as follows: the DSP processor... Figure 1The “TEST” port, when input with a fixed-frequency square wave signal (such as a 3kHz square wave signal), immediately turns on transistor Q1. This square wave signal is then applied to current transformer CT1. Because the current transformer CT1 is loaded with a 3kHz square wave signal, it can detect sudden changes in the AC components of the output current, such as the 3kHz frequency and its harmonics (6kHz, 9kHz, 12kHz, etc.). These sudden changes in AC components are then amplified by a turns ratio of 160 and passed through… Figure 1 The CT+ port input is given to Figure 2 The signal sampling and amplification circuit 20 described herein performs subsequent signal amplification, filtering, and proportional amplification processing before transmitting the signal to the DSP processor for arc fault analysis.

[0064] like Figure 2 As shown, the signal sampling amplifier circuit 20 includes rectifiers D1 and D2, amplifier U2A, resistors R6, R7, R9, R10, R11, R25, R26, R27, and capacitors C14, C15, and C21. The non-inverting input terminal of amplifier U2A is connected in series with resistor R6 to serve as the first signal input terminal 100 of the signal sampling amplifier circuit, and the inverting input terminal is connected in series with resistor R26 to serve as the second signal input terminal 200 of the signal sampling amplifier circuit.

[0065] Resistor R27 is connected between the inverting input and output of amplifier U2A; resistors R10 and R11 connected in parallel are connected in series with rectifier D2. One end of resistors R10 and R11 connected in series is connected to the non-inverting input of amplifier U2A, and the other end is connected in series with rectifier D2 and resistor R26 and then connected to the inverting input of amplifier U2A.

[0066] One end of capacitors C14 and C15 connected in parallel is connected to the non-inverting input of amplifier U2A, and the other end is connected to the inverting input of amplifier U2A after being connected in series with resistor R26.

[0067] One end of the resistors R9 and R25, which are connected in series, is connected to the non-inverting input of amplifier U2A after being connected in series with resistor R6, and the other end is connected to the inverting input of amplifier U2A after being connected in series with resistor R26.

[0068] The rectifier D1 is connected in parallel between the resistors R9 and R25, which are connected in series.

[0069] The output terminal of amplifier U2A is connected in series with resistor R7 and then serves as the signal output terminal of the signal sampling and amplification circuit, which is connected to the input terminal of the filter circuit. The power input terminal of amplifier U2A is connected to the 5V voltage output terminal +5VARC of the power supply circuit, and the ground terminal is grounded.

[0070] One end of capacitor C21 is connected in series with resistor R26 and then connected to the inverting input terminal of amplifier U2A and the 2.5V voltage output terminal VREF of the power supply circuit.

[0071] The filter circuit includes, for example: Figure 2 The first high-pass filter circuit 20 shown in the figure includes an amplifier U3B, resistors R15, R16, R17, R8, C19, and C20. One end of the capacitor C20 serves as the input terminal of the first high-pass filter circuit and is connected to the signal output terminal of the signal sampling amplifier circuit. The other end is connected in series with capacitor C19 and then connected to the non-inverting input terminal of the amplifier U3B.

[0072] One end of resistors R15 and R16 connected in parallel is connected to the inverting input terminal of amplifier U3B, and the other end is connected to the non-inverting input terminal of amplifier U3B after being connected in series with capacitor C19.

[0073] One end of resistor R17 is connected to the non-inverting input of amplifier U3B, and the other end is connected in series with resistor R8 and then connected to the 2.5V voltage output terminal VREF of the power supply circuit.

[0074] The output of amplifier U3B is connected to its inverting input and serves as the signal output of the first high-pass filter circuit.

[0075] To enhance the filtering effect, preferably, the filtering circuit also includes Figure 3 The second high-pass filter circuit 30 shown includes an amplifier U3A, capacitors C18 and C17, and resistors R12, R13, R14, and R19. The non-inverting input terminal of the amplifier U3A is connected to capacitors C17 and C18 in sequence and then connected to the signal output terminal of the first high-pass filter circuit.

[0076] One end of resistors R12 and R13 connected in parallel is connected to the inverting input terminal of amplifier U3A, and the other end is connected in series with capacitor C17 and then connected to the non-inverting input terminal of amplifier U3A.

[0077] One end of resistor R19 is connected to the non-inverting input of amplifier U3A, and the other end is connected in series with resistor R14 and then connected to the 2.5V voltage output terminal VREF of the power supply circuit.

[0078] The power input terminal of amplifier U3A is connected to the 5V voltage output terminal +5VARC of the power supply circuit, and the ground terminal is grounded.

[0079] The output of amplifier U3A is connected to its inverting input and serves as the signal output of the second high-pass filter circuit.

[0080] The working principle of the first and second high-pass filter circuits is as follows: signals above a certain critical frequency can pass through, while signals below that critical frequency cannot pass through, thereby achieving high-pass filtering of the signal.

[0081] More preferably, the filter circuit also includes Figure 3The first low-pass filter circuit 40 shown includes an amplifier U4A, capacitors C13 and C16, and resistors R21, R22, R23, and R24. The non-inverting input terminal of the amplifier U4A is connected to the signal output terminal of the second high-pass filter circuit after being connected in series with resistors R24, R23, R22, and R21 in sequence. The inverting input terminal is connected to its non-inverting input terminal after being connected in series with capacitor C13 and resistors R23 and R24 in sequence.

[0082] One end of capacitor C16 is connected to the non-inverting input terminal of amplifier U4A, and the other end is connected to the 2.5V voltage output terminal VREF of the power supply circuit.

[0083] The inverting input of amplifier U4A is also connected to its output. The power input is connected to the 5V voltage output of the power supply circuit, +5VARC. The ground terminal is grounded, and the output terminal serves as the signal output of the first low-pass filter circuit.

[0084] More preferably, the filter circuit also includes Figure 3 The second low-pass filter circuit 50 shown includes an amplifier U2B, resistors R20, R18, C10, C11, and C12. The non-inverting input terminal of the amplifier U2B is connected to the signal output terminal of the first low-pass filter circuit after being connected in series with resistors R18 and R20. The inverting input terminal is connected to its own non-inverting input terminal after being connected in series with capacitor C10 and resistor R18.

[0085] One end of capacitors C11 and C12, which are connected in parallel, is connected to the non-inverting input terminal of amplifier U2B, and the other end is connected to the 2.5V voltage output terminal VREF of the power supply circuit.

[0086] The inverting input of amplifier U2B is also connected to its output, which serves as the signal output of the second low-pass filter circuit.

[0087] The working principle of the first and second low-pass filter circuits is as follows: signals below a certain critical frequency can pass through, while signals above the critical frequency cannot pass through, thereby achieving low-pass filtering of the signal.

[0088] A proportional amplifier circuit of 60 is as follows Figure 3 As shown, the circuit includes amplifier U4B, capacitor C24, resistors R28, R29, R30, R31, R32 and capacitor C25. The non-inverting input terminal of amplifier U4B is connected to the signal output terminal of the filter circuit after being connected in series with resistor R32, and the inverting input terminal is connected to ground after being connected in series with resistor R30.

[0089] Capacitor C24 is connected between the inverting input and output of amplifier U4B; one end of resistor R28 is connected to the output of amplifier U4B, and the other end is connected in series with resistors R29 and R30 and then grounded. The series resistors R28 and R29 are connected between the output and inverting input of amplifier U4B.

[0090] The output of amplifier U4B is connected to the ARC-AD port of the DSP processor via a series resistor R31 to transmit the acquired arc signal to the DSP processor.

[0091] One end of capacitor C25 is connected in series with resistor R31 and then connected to the output terminal of U4B, while the other end is grounded.

[0092] The power supply circuit is as follows Figure 4 As shown, it includes inductor L1, voltage regulator U1, capacitors C1-C8, resistors R1 and R2. One end of inductor L1 is connected to an external 5V power supply and is connected in series with capacitors C3 and C2 to the other end of its 5V voltage output terminal +5VARC, which serves as the power supply circuit. Capacitor C4 is connected in parallel across capacitor C3, and capacitor C1 is connected in parallel across capacitor C2.

[0093] One end of resistor R1 is connected to the 5V voltage output terminal +5VARC of the power supply circuit, and the other end is connected to pin 2 of voltage regulator U1. Pin 3 of voltage regulator U1 is grounded, pin 1 is connected to one end of resistor R2, and the other end of resistor R2 is connected to the 5V voltage output terminal +5VARC.

[0094] Capacitor C5 is connected in parallel across resistor R2;

[0095] Capacitor C6 is connected in parallel across capacitor C5;

[0096] Capacitor C7 is connected between pin 2 and pin 3 of voltage regulator U1;

[0097] Capacitor C8 is connected in parallel across capacitor C7;

[0098] Pin 2 of voltage regulator U1 is connected to the intersection point A of pin 1 of voltage regulator U1 and resistor R2. Intersection point A is connected to the intersection point B of capacitor C5 and capacitor C7. Intersection point B is connected to the intersection point C of capacitor C6 and capacitor C8. Intersection point C serves as the 2.5V voltage output terminal VREF of the power supply circuit.

[0099] The following describes the method for performing arc detection on the device under test using the arc detection circuit provided in this embodiment:

[0100] like Figure 5 As shown, the arc detection method includes the following steps:

[0101] S1, the automatic detection circuit in the arc detection circuit with automatic detection function loads the DSP signal received by the external DSP processor onto the current transformer CT1.

[0102] S2, after the current transformer CT1 is loaded with a DSP signal, the AC component of the current output from the line it is connected to is extracted according to the fixed frequency and harmonic frequency of the DSP signal and input to the signal sampling and amplification circuit in the arc detection circuit for signal amplification and output.

[0103] S3, the filter circuit in the arc detection circuit filters the current signal after signal amplification and outputs it;

[0104] S4, the proportional amplifier circuit in the arc detection circuit performs signal proportional amplification on the filtered current signal and outputs it to the DSP processor.

[0105] The S5 DSP processor analyzes whether an arc fault has occurred in the line based on the received current signal and outputs the analysis results.

[0106] The principle of DSP processor analysis for arc faults is briefly described below:

[0107] When no electric arc occurs, the AC component in the output current of the circuit is very simple, generally consisting only of the circuit's operating frequency and its harmonics. However, when an electric arc occurs in the circuit under test, the AC components of different frequencies become very dense, but are mainly concentrated in the 10-100kHz range. The filtering circuit in the arc detection circuit provided in this embodiment mainly filters out AC components outside the 10-100kHz range. The DSP samples the AC signal and then compares it before and after. When the distribution of 10 typical points in the 10-100kHz range all show positive spikes exceeding a certain threshold, an arc fault is identified. For example... Figure 6 As shown in the diagram, when no electric arc occurs, the AC spectrum 300 is very uniform, while when an electric arc occurs, as... Figure 7 As shown, the AC spectrum 400 becomes more diverse, indicating that the AC component is rich when the arc occurs. This invention utilizes the characteristic that the AC spectrum changes significantly before and after the arc occurs to determine whether an arc fault has occurred.

[0108] In addition, the present invention also provides an arc detection device, which is internally equipped with the aforementioned arc detection circuit with automatic detection function.

[0109] It should be stated that the above-described specific embodiments are merely preferred embodiments of the present invention and the technical principles employed. Those skilled in the art should understand that various modifications, equivalent substitutions, and variations can be made to the present invention. However, such variations, as long as they do not depart from the spirit of the present invention, should be within the scope of protection of the present invention. Furthermore, some terminology used in this specification and claims is not limiting, but merely for ease of description.

Claims

1. An arc detection circuit with automatic detection function, characterized in that, The system includes an automatic detection circuit, a signal sampling and amplification circuit, a filtering circuit, a proportional amplification circuit, and a power supply circuit for each circuit, all connected in sequence. The first port of the current transformer CT1 in the automatic detection circuit is connected to the current output terminal of the line to be detected for arc faults, and the third port is connected to the current input terminal of the line. After receiving a DSP signal from an external DSP processor, the automatic detection circuit is activated. The current transformer CT1 extracts abrupt changes in the AC component of the current output from the line according to the fixed frequency and harmonic frequencies of the DSP signal. These amplified, filtered, and amplified AC signal is then sequentially processed by the signal sampling and amplification circuit, the filtering circuit, and the proportional amplification circuit before being output to the externally connected DSP processor for further arc fault analysis of the line.

2. The arc detection circuit with automatic detection function according to claim 1, characterized in that, The automatic detection circuit includes the current transformer CT1, transistor Q1, resistors R3, R4, R5, and capacitor C9. One end of resistor R4 serves as the input terminal of the DSP signal, connected to the DSP signal output terminal of the DSP processor, and the other end is connected to the base of transistor Q1. Resistor R5 is connected between the base and emitter of transistor Q1, and the emitter of transistor Q1 is grounded. Capacitor C9 is connected in parallel across resistor R5. One end of resistor R3 is connected to the collector of transistor Q1, and the other end is connected to the fourth port of current transformer CT1. The fourth port of current transformer CT1 is also connected to the first electrical input terminal (100) of the signal sampling amplification circuit, and the third port is connected to the second electrical input terminal (200) of the signal sampling amplification circuit and to the 2.5V voltage output terminal VREF of the power supply circuit.

3. The arc detection circuit with automatic detection function according to claim 1 or 2, characterized in that, The signal sampling and amplification circuit includes rectifiers D1 and D2, amplifier U2A, resistors R6, R7, R9, R10, R11, R25, R26, R27, and capacitors C14, C15, and C21. The non-inverting input terminal of amplifier U2A is connected in series with resistor R6 to serve as the first signal input terminal (100) of the signal sampling and amplification circuit, and the inverting input terminal is connected in series with resistor R26 to serve as the second signal input terminal (200) of the signal sampling and amplification circuit. The resistor R27 is connected between the inverting input terminal and the output terminal of the amplifier U2A; the resistors R10 and R11 connected in parallel are connected in series with the rectifier D2, one end of the resistors R10 and R11 connected in series is connected to the non-inverting input terminal of the amplifier U2A, and the other end is connected in series with the rectifier D2 and the resistor R26 and then connected to the inverting input terminal of the amplifier U2A. One end of the capacitors C14 and C15 connected in parallel is connected to the non-inverting input terminal of the amplifier U2A, and the other end is connected in series with the resistor R26 and then connected to the inverting input terminal of the amplifier U2A. One end of the resistors R9 and R25, which are connected in series, is connected in series with resistor R6 and then connected to the non-inverting input terminal of amplifier U2A; the other end is connected in series with resistor R26 and then connected to the inverting input terminal of amplifier U2A. The rectifier D1 is connected in parallel between the resistors R9 and R25, which are connected in series. The output terminal of the amplifier U2A is connected in series with the resistor R7 and then serves as the signal output terminal of the signal sampling amplification circuit, which is connected to the input terminal of the filter circuit; the power input terminal of the amplifier U2A is connected to the 5V voltage output terminal +5VARC of the power supply circuit, and the ground terminal is grounded. One end of the capacitor C21 is connected in series with the resistor R26 and then connected to the inverting input terminal of the amplifier U2A and the 2.5V voltage output terminal VREF of the power supply circuit.

4. The arc detection circuit with automatic detection function according to claim 3, characterized in that, The filtering circuit includes a first high-pass filter circuit, which includes an amplifier U3B, resistors R15, R16, R17, R8, C19, and C20. One end of the capacitor C20 serves as the input terminal of the first high-pass filter circuit and is connected to the signal output terminal of the signal sampling amplification circuit. The other end is connected in series with the capacitor C19 and then connected to the non-inverting input terminal of the amplifier U3B. One end of the resistors R15 and R16 connected in parallel is connected to the inverting input terminal of the amplifier U3B, and the other end is connected in series with the capacitor C19 and then connected to the non-inverting input terminal of the amplifier U3B. One end of the resistor R17 is connected to the non-inverting input terminal of the amplifier U3B, and the other end is connected in series with the resistor R8 and then connected to the 2.5V voltage output terminal VREF of the power supply circuit. The output terminal of the amplifier U3B is connected to its inverting input terminal and serves as the signal output terminal of the first high-pass filter circuit.

5. The arc detection circuit with automatic detection function according to claim 4, characterized in that, The filtering circuit also includes a second high-pass filter circuit, which includes an amplifier U3A, capacitors C18 and C17, and resistors R12, R13, R14, and R19. The non-inverting input terminal of the amplifier U3A is connected to the capacitors C17 and C18 in sequence and then connected to the signal output terminal of the first high-pass filter circuit. One end of the resistors R12 and R13 connected in parallel is connected to the inverting input terminal of the amplifier U3A, and the other end is connected in series with the capacitor C17 and then connected to the non-inverting input terminal of the amplifier U3A. One end of the resistor R19 is connected to the non-inverting input terminal of the amplifier U3A, and the other end is connected in series with the resistor R14 and then connected to the 2.5V voltage output terminal VREF of the power supply circuit. The power input terminal of the amplifier U3A is connected to the 5V voltage output terminal +5VARC of the power supply circuit, and the ground terminal is grounded. The output terminal of the amplifier U3A is connected to its inverting input terminal and serves as the signal output terminal of the second high-pass filter circuit.

6. The arc detection circuit with automatic detection function according to claim 5, characterized in that, The filtering circuit further includes a first low-pass filter circuit, which includes an amplifier U4A, capacitors C13 and C16, and resistors R21, R22, R23, and R24. The non-inverting input terminal of the amplifier U4A is connected in series with the resistors R24, R23, R22, and R21 and then connected to the signal output terminal of the second high-pass filter circuit. The inverting input terminal is connected in series with the capacitor C13 and the resistors R23 and R24 and then connected to its non-inverting input terminal. One end of the capacitor C16 is connected to the non-inverting input terminal of the amplifier U4A, and the other end is connected to the 2.5V voltage output terminal VREF of the power supply circuit. The inverting input of the amplifier U4A is also connected to its output. The power input is connected to the 5V voltage output +5VARC of the power supply circuit. The grounding terminal is grounded, and the output terminal serves as the signal output of the first low-pass filter circuit.

7. The arc detection circuit with automatic detection function according to claim 6, characterized in that, The filtering circuit further includes a second low-pass filter circuit, which includes an amplifier U2B, resistors R20, R18, C10, C11, and C12. The non-inverting input terminal of the amplifier U2B is connected in series with the resistors R18 and R20 and then connected to the signal output terminal of the first low-pass filter circuit. The inverting input terminal is connected in series with the capacitor C10 and the resistor R18 and then connected to its own non-inverting input terminal. One end of the capacitors C11 and C12, which are connected in parallel with each other, is connected to the non-inverting input terminal of the amplifier U2B, and the other end is connected to the 2.5V voltage output terminal VREF of the power supply circuit. The inverting input of the amplifier U2B is also connected to its output, which serves as the signal output of the second low-pass filter circuit.

8. The arc detection circuit with automatic detection function according to any one of claims 1, 4-7, characterized in that, The proportional amplifier circuit includes amplifier U4B, capacitor C24, resistors R28, R29, R30, R31, R32 and capacitor C25. The non-inverting input terminal of amplifier U4B is connected in series with resistor R32 and then connected to the signal output terminal of the filter circuit. The inverting input terminal is connected in series with resistor R30 and then grounded. The capacitor C24 is connected between the inverting input terminal and the output terminal of the amplifier U4B; one end of the resistor R28 is connected to the output terminal of the amplifier U4B, and the other end is connected in series with the resistors R29 and R30 and then grounded. The resistors R28 and R29, which are connected in series, are connected between the output terminal and the inverting input terminal of the amplifier U4B. The output of the amplifier U4B is connected in series with the resistor R31 and then connected to the ARC-AD port of the DSP processor to transmit the acquired arc signal to the DSP processor. One end of the capacitor C25 is connected in series with the resistor R31 and then connected to the output terminal of the U4B, while the other end is grounded.

9. An arc detection device, characterized in that, The arc detection device is equipped with an arc detection circuit with automatic detection function as described in any one of claims 1-8.

10. An arc detection method, characterized in that the steps include... include: S1, the automatic detection circuit in the arc detection circuit with automatic detection function as described in any one of claims 1-8 loads the received DSP signal sent by the external DSP processor onto the current transformer CT1. S2, after the current transformer CT1 is loaded with the DSP signal, it extracts the AC component of the current output from the line it is connected to according to the fixed frequency and harmonic frequency of the DSP signal and inputs it to the signal sampling and amplification circuit in the arc detection circuit for signal amplification processing before output. S3, the filtering circuit in the arc detection circuit filters the current signal after signal amplification and outputs it; S4, the proportional amplifier circuit in the arc detection circuit performs signal proportional amplification processing on the filtered current signal and outputs it to the DSP processor; S5, the DSP processor analyzes whether an arc fault has occurred in the line based on the received current signal and outputs the analysis result.

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