Direct current and arc discharge current detection device

Abstract

The utility model relates to the technical field of arc discharge current detection, and discloses a direct current and arc discharge current detection device, which comprises a magnetic core provided with an air gap; a to-be-detected current lead passes through the magnetic core; a feedback coil wound on a first position of the magnetic core; the magnetic sensing chip is placed at a specified position of the magnetic core so as to sense a magnetic field at the air gap; the first signal processing module is used for receiving a target signal sent by the magnetic sensing chip and providing feedback current for the feedback coil according to the target signal; and the second signal processing module is used for receiving the output signal of the first signal processing module and filtering the output signal to respectively obtain an alternating current arc discharge signal and a direct current signal. The device has relatively good following performance and extremely fast step response time, and the detection precision of the direct current and arc discharge current detection device is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of arc current detection, in particular to a DC and arc current detection device. Background Art

[0002] There is high voltage in energy storage devices. The high voltage ionizes gas to generate ions and electrons, and the current excites the ionized air to generate an arc. The arc can cause physical damage to the device, such as burning of components or cables. In severe cases, it can lead to fire or electric shock, posing a great potential safety hazard.

[0003] In the prior art, devices or components for detecting arcs are usually provided in the circuit structure of energy storage devices. By detecting the arc, potential safety hazards can be discovered and eliminated in a timely manner to protect the device. However, in addition to detecting arc current, DC current detection is also essential. Usually, the device for detecting DC current and the device for detecting arc current are separate devices, or two magnetic cores are provided in one device for measuring DC current and arc current respectively.

[0004] In the above solutions, different magnetic cores need to be set to detect DC current and arc current simultaneously, and mutual interference is likely to occur between the two magnetic cores, resulting in low detection accuracy. Summary of the Utility Model

[0005] In view of this, the present application provides a DC and arc current detection device with improved detection accuracy. The device includes:

[0006] A magnetic core with an air gap provided thereon; a wire carrying the current to be measured passes through the magnetic core;

[0007] A feedback coil wound around the magnetic core at a first position;

[0008] A magnetic sensing chip placed at a designated position of the magnetic core to sense the magnetic field at the air gap;

[0009] A first signal processing module electrically connected to the magnetic sensing chip and the feedback coil respectively; the first signal processing module is configured to receive a target signal sent by the magnetic sensing chip and provide a feedback current to the feedback coil according to the target signal;

[0010] A second signal processing module electrically connected to the first signal processing module; the second signal processing module is configured to receive the output signal of the first signal processing module and filter the output signal to obtain an AC arc signal and a DC signal respectively.

[0011] In a possible implementation, the magnetic sensing chip is placed at the air gap of the magnetic core; alternatively, the magnetic sensing chip is arranged close to the air gap of the magnetic core.

[0012] In a possible implementation, the magnetic sensing chip is a TMR chip.

[0013] In a possible implementation, the first signal processing module includes a first operational amplifier; the input end of the first operational amplifier is used to access the output signal of the magnetic sensing chip;

[0014] The positive output end of the first operational amplifier is connected to the first end of the target resistor through the feedback coil; the second end of the target resistor is connected to the negative output end of the first operational amplifier; the voltage value on the target resistor is transmitted to the second signal processing module as the output signal of the first signal processing module.

[0015] In a possible implementation, the second signal processing module includes a first-stage amplification circuit, a filtering circuit, and a second-stage amplification circuit;

[0016] The first-stage amplification circuit is electrically connected to the first signal processing module to receive and amplify the output signal of the first signal processing module, obtaining a first amplified signal; the first-stage amplification circuit is used to output the first amplified signal through the AC / DC output terminal;

[0017] The filtering circuit is used to receive the first amplified signal and perform filtering processing, obtaining an AC signal and transmitting it to the second-stage amplification circuit;

[0018] The second-stage amplification circuit is used to receive the AC signal and perform amplification processing, obtaining a second amplified signal and outputting it through the arcing output terminal.

[0019] In a possible implementation, the first-stage amplification circuit includes a second operational amplifier, a first resistor, a second resistor, a third resistor, and a fourth resistor;

[0020] The positive input end of the second operational amplifier is connected to the first end of the target resistor through the first resistor; the negative input end of the second operational amplifier is connected to the second end of the target resistor through the second resistor;

[0021] The positive input end of the second operational amplifier is also connected to the output end of the second operational amplifier through the third resistor; the negative input end of the second operational amplifier is also connected to the output end of the second operational amplifier through the fourth resistor;

[0022] The output end of the second operational amplifier is respectively connected to the AC / DC output terminal and the output end of the filtering circuit.

[0023] In a possible implementation, the filtering circuit includes a first capacitor and a second capacitor; the two-stage amplifier circuit includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a third operational amplifier;

[0024] The first end of the first capacitor is connected to the output end of the second operational amplifier; the first end of the second capacitor is connected to a first reference voltage terminal;

[0025] The second end of the first capacitor is connected to the positive input terminal of the third operational amplifier through the fifth resistor; the positive input terminal of the third operational amplifier is also connected to a second reference voltage terminal through the seventh resistor;

[0026] The second end of the second capacitor is connected to the negative input terminal of the third operational amplifier through the sixth resistor; the negative input terminal of the third operational amplifier is also connected to the output end of the third operational amplifier through the eighth resistor;

[0027] The output end of the third operational amplifier is connected to the arc striking output terminal.

[0028] In a possible implementation, the device further includes a self-check module; the self-check module includes a self-check coil and a self-check circuit;

[0029] The self-check coil is wound around the magnetic core; the first end of the self-check coil is grounded; the second end of the self-check coil is connected to the self-check circuit;

[0030] The self-check circuit is used to provide a self-check current for the self-check coil.

[0031] In a possible implementation, when the self-check circuit is started, the magnetic sensing chip is used to detect the magnetic field generated by the self-check coil and generate a corresponding self-check signal for processing by the first signal processing module and the second signal processing module.

[0032] In a possible implementation, the self-check circuit includes a first self-check diode, a second self-check diode, a first self-check resistor, a second self-check resistor, a third self-check resistor, a zener diode, and a self-check triode;

[0033] In the self-check circuit, the collector of the self-check triode is connected to the power supply voltage terminal through the first self-check resistor;

[0034] The base of the self-check triode is connected to the trigger pin of the self-check module through the second self-check resistor; the trigger pin is connected to the negative electrode of the first self-check diode; the positive electrode of the first self-check diode is grounded; the base of the self-check triode is also connected to the negative electrode of the zener diode; the positive electrode of the zener diode is grounded; the control terminal of the zener diode is connected to the emitter of the self-check triode;

[0035] The emitter of the self-checking triode is also connected to the second end of the self-checking coil through a third self-checking resistor; the emitter of the self-checking triode is also connected to the cathode of a second self-checking diode; the anode of the second self-checking diode is grounded.

[0036] The technical solution provided by this application may include the following beneficial effects:

[0037] In the DC and arc current detection device of this application, the wire of the current to be measured passes through the magnetic core. The magnetic core responds to the current flowing through the wire of the current to be measured and generates a corresponding magnetic field at the air gap of the magnetic core. At this time, when the magnetic sensing chip senses the magnetic field at the air gap, it generates a corresponding target signal and transmits it to the first signal processing module. On the one hand, the first signal processing module generates a feedback current corresponding to the magnitude of the magnetic field at the air gap to supply to the feedback coil, so that the feedback coil generates an induced magnetic field to cancel the magnetic field at the air gap. On the other hand, the first signal processing module processes the target signal generated by the magnetic sensing chip and transmits it to the second signal processing module, so that the second signal processing module amplifies and filters the target signal and then respectively identifies the arc signal and the DC signal and outputs them. The above device can keep the magnetic field at the air gap balanced, and further make the magnetic field at the air gap change little with the change of the wire of the current to be measured and change quickly in frequency, with good followability and extremely fast step response time, thereby improving the detection accuracy of the DC and arc current detection device. Description of the Drawings

[0038] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 It is a schematic structural diagram of a DC and arc current detection device shown according to an exemplary embodiment.

[0040] Figure 2 It shows the specific circuit diagram of the DC and arc current detection device involved in the embodiment of this application.

[0041] Figure 3 It shows the full-temperature range accuracy test result diagram involved in the embodiment of this application.

[0042] Figure 4 It is a schematic structural diagram of a DC and arc current detection device shown according to an exemplary embodiment.

[0043] Figure 5 The circuit structure diagram of a self-checking circuit involved in an embodiment of the present application is shown. Specific embodiments

[0044] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0045] In the description of the embodiments of the present application, the term "corresponding" may indicate a direct or indirect corresponding relationship between two entities, may also indicate an associated relationship between two entities, or may be a relationship such as indication and being indicated, configuration and being configured, etc.

[0046] Figure 1 is a schematic structural diagram of a DC and arcing current detection device shown according to an exemplary embodiment. As Figure 1 shown, the device includes:

[0047] A magnetic core 101 with an air gap provided thereon; a wire 102 of the current to be measured passes through the magnetic core 101;

[0048] A feedback coil 103 wound around the magnetic core 101;

[0049] A magnetic sensing chip 104 placed at a specified position of the magnetic core 101 to sense the magnetic field at the air gap;

[0050] A first signal processing module 105 electrically connected to the magnetic sensing chip 104 and the feedback coil 103 respectively; the first signal processing module 105 is configured to receive a target signal sent by the magnetic sensing chip 104 and provide a feedback current to the feedback coil 103 according to the target signal;

[0051] A second signal processing module 106 electrically connected to the first signal processing module 105; the second signal processing module 106 is configured to receive an output signal of the first signal processing module 105 and filter the output signal to obtain an AC arcing signal and a DC signal respectively.

[0052] In as Figure 1In the DC and arc current detection device shown, when the current-carrying wire 102 to be measured passes through the magnetic core, the magnetic core 101 responds to the current flowing through the current-carrying wire 102 to be measured and generates a corresponding magnetic field at the air gap of the magnetic core 101. At this time, when the magnetic sensing chip 104 senses the magnetic field at the air gap, it generates a corresponding target signal and transmits it to the first signal processing module 105;

[0053] On the one hand, the first signal processing module 105 generates a feedback current corresponding to the output of the magnetic sensing chip and supplies it to the feedback coil 103, so that the feedback coil 103 generates an induced magnetic field to cancel the magnetic field at the air gap;

[0054] On the other hand, the first signal processing module 105 processes the target signal generated by the magnetic sensing chip 104 and transmits it to the second signal processing module 106, so that the second signal processing module 106 amplifies and filters the target signal, and then identifies the arc signal and the DC signal and outputs them respectively.

[0055] And in the Figure 1 The DC and arc current detection device shown adopts a closed-loop detection principle. When a certain current (primary current, also called the current to be measured) passes through the current-carrying wire to be measured, the change of the current generates a magnetic field, and the magnetic sensing chip 104 detects the change of the magnetic field and converts the magnetic field into a voltage signal (i.e., the target signal).

[0056] In the closed-loop mode, after the magnetic field at the air gap remains balanced, the change amplitude will be very small. The smaller the change amplitude, the faster the change frequency, and the better the followability and extremely fast step response time of the primary current (the measured current).

[0057] Since the magnetic field generated by the feedback coil 103 in the magnetic core 101 is opposite to the magnetic field generated by the primary current in the magnetic core, that is, the magnetic field generated by the feedback coil 103 in the magnetic core 101 cancels the magnetic field generated by the current-carrying wire to be measured in the magnetic core 101 under normal conditions, thus achieving zero magnetic flux in the magnetic core, reducing the influence of the magnetic core on the accuracy, and improving the detection accuracy and linearity of the detection device.

[0058] Optionally, as Figure 1 shown, the magnetic sensing chip 104 is placed at the air gap of the magnetic core 101.

[0059] Optionally, the magnetic sensing chip 104 can also be arranged close to the air gap of the magnetic core, for example, on one side of the air gap of the magnetic core, to measure the magnetic field strength at the air gap of the magnetic core.

[0060] Optionally, the magnetic sensing chip is a TMR (tunnel magnetoresistance) chip. TMR has the advantages of high precision, high sensitivity, low power consumption, small size, good temperature stability, and a wide operating temperature range. Moreover, the TMR chip has built-in temperature compensation, which can well ensure the accuracy of the detection device in the full temperature range.

[0061] Further, as Figure 1 shown, the second signal processing module 106 in the embodiment of the present application further includes a first-stage amplifier circuit 1061, a filter circuit 1062, and a second-stage amplifier circuit 1063;

[0062] The first-stage amplifier circuit 1061 is electrically connected to the first signal processing module 105 to receive and amplify the output signal of the first signal processing module 105, obtaining a first amplified signal; the first-stage amplifier circuit is used to output the first amplified signal through the AC / DC output terminal;

[0063] The filter circuit 1062 is used to receive the first amplified signal and perform filtering processing, obtaining an AC signal and transmitting it to the second-stage amplifier circuit;

[0064] The second-stage amplifier circuit 1063 is used to receive the AC signal and perform amplification processing, obtaining a second amplified signal and outputting it through the arc-striking output terminal.

[0065] Figure 2 shows the specific circuit diagram of the DC and arc-striking current detection device involved in the embodiment of the present application. As Figure 2 shown, Figure 1 the first signal processing module 105 in

[0066] includes a first operational amplifier U1; the input terminal of the first operational amplifier U1 is used to access the output signal of the magnetic sensing chip 104;

[0067] The positive output terminal of the first operational amplifier U1 is connected to the first end of the target resistor R0 through the feedback coil 103; the second end of the target resistor R0 is connected to the negative output terminal of the first operational amplifier U1; the voltage value on the target resistor R0 is used as the output signal of the first signal processing module 105 and transmitted to the second signal processing module 106. Figure 2 Further, as

[0068] The positive input terminal of the second operational amplifier U2 is connected to the first end of the target resistor R0 through the first resistor R1; the negative input terminal of the second operational amplifier U2 is connected to the second end of the target resistor R0 through the second resistor R2; at this time, the voltage value on the target resistor R0 is input as the output signal of the first signal processing module 105 to the second operational amplifier U2.

[0069] The positive input terminal of the second operational amplifier U2 is also connected to the output terminal of the second operational amplifier U2 through the third resistor R3; the negative input terminal of the second operational amplifier U2 is also connected to the output terminal of the second operational amplifier U2 through the fourth resistor R4;

[0070] The output terminal of the second operational amplifier U2 is respectively connected to the AC / DC output terminal AD_Vout and the output terminal of the filter circuit 1062. At this time, the output terminal of the second operational amplifier U2 is connected to the AC / DC output terminal AD_Vout, and at this time, the AC / DC signal output by the AC / DC output terminal AD_Vout is the AC / DC signal reflecting the magnitude of the DC current flowing through the current-carrying wire to be measured.

[0071] As Figure 2 shown in the first-stage amplifier circuit 1061, the second operational amplifier U2, the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 form an amplifier circuit, amplify the voltage value on the target resistor R0 and output it through the output terminal of the second operational amplifier U2.

[0072] And in order to obtain the AC arc signal, further, as Figure 2 shown, a filter circuit 1062 is provided in the second signal processing module 106, and the filter circuit 1062 includes a first capacitor C1 and a second capacitor C2; the second-stage amplifier circuit includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a third operational amplifier U3;

[0073] The first end of the first capacitor C1 is connected to the output terminal of the second operational amplifier U2; the first end of the second capacitor C2 is connected to the first reference voltage terminal.

[0074] At this time, the second signal processing module 106 filters the DC signal in the signal output from the output terminal of the second operational amplifier U2 through the first capacitor C1 and the second capacitor C2, and outputs the filtered AC signal to the second-stage amplifier circuit 1063 for processing.

[0075] As Figure 2 shown, the second end of the first capacitor C1 is connected to the positive input terminal of the third operational amplifier U3 through the fifth resistor R5; the positive input terminal of the third operational amplifier U3 is also connected to the second reference voltage terminal through the seventh resistor R7;

[0076] The second terminal of the second capacitor C2 is connected to the negative input terminal of the third operational amplifier U3 through the sixth resistor R6; the negative input terminal of the third operational amplifier U3 is also connected to the output terminal of the third operational amplifier U3 through the eighth resistor R8;

[0077] The output terminal of the third operational amplifier U3 is connected to the arcing output terminal AC_Vout.

[0078] Optionally, in the embodiments of the present application, both the first reference voltage terminal and the second reference voltage terminal are Vref, and the value of Vref can be set according to actual requirements. Exemplarily, in the embodiments of the present application, Vref is 2.5V;

[0079] Optionally, in the embodiments of the present application, the first reference voltage terminal and the second reference voltage terminal can also be respectively connected to reference voltage values of different magnitudes.

[0080] When the AC signal obtained by filtering through the filter circuit 1062 is processed by the two-stage amplification circuit 1063 and output through the arcing output terminal AC_Vout, the signal output by the arcing output terminal AC_Vout at this time represents the magnitude of the arcing current in the current-carrying wire to be measured.

[0081] Such as Figure 1 Or as Figure 2 The DC and arcing current detection device shown adopts the closed-loop design principle. The current-carrying wire to be measured passes through a certain current (primary current, also known as the current to be measured). The change in the current generates a magnetic field. The magnetic sensor chip detects the change in the magnetic field and converts the magnetic field into a voltage signal, which is output to the first signal processing module. After being processed by the first signal processing module, a current is provided to the feedback coil. The magnetic field generated by the feedback coil at the air gap of the magnetic core is opposite in direction and equal in magnitude to the magnetic field generated by the primary current at the air gap of the magnetic core, canceling each other out, achieving zero magnetic flux, and maintaining magnetic balance.

[0082] The above device realizes the output of DC signals and AC arcing signals through the second signal processing module. The signal output by the magnetic sensing chip is processed by the first signal processing module and then output to the first-stage amplification circuit of the second signal processing module. After being processed by the first-stage amplification circuit, an AC-DC voltage signal is output through the AC-DC output terminal AD_Vout. At the same time, due to the AC-pass and DC-block function of the filter circuit ( Figure 2 in which are the first capacitor C1 and the second capacitor C2), after the DC signal is filtered out from the output of the first-stage amplification circuit by the filter circuit, the AC signal is output to the second-stage amplification circuit, and after being processed by the second-stage amplification circuit, an AC voltage signal is output through the arcing output terminal AC_Vout.

[0083] Moreover, the design of the present application can achieve good followability of the primary-side current (measured current) and extremely fast step response time. In the closed-loop mode, after the magnetic field at the air gap reaches balance, the change amplitude is very small. With a small change amplitude, the change frequency is faster, and the present application has good followability of the primary-side current (measured current) and extremely fast step response time.

[0084] Figure 3 Fig. shows the full-temperature range accuracy test results of the embodiments of the present application. As Figure 3 shown, two products corresponding to this structure are randomly selected to test the accuracy of the current sensor in the full-temperature range. Since it works in the zero-flux state, the non-linearity and hysteresis effect of the magnetic core do not affect the output. Compared with open-loop products, better linearity and higher accuracy can be obtained. As shown by No. 1# and No. 2# (corresponding to different products respectively), the full-temperature range accuracy can reach within eight-thousandths. Accuracy calculation formula: X = ((AD_Vout – Vref)@In@25°C – Voe@25°C – G_th*In) / V_FS. After taking the difference between AD_Vout and Vref, subtract the 0-point offset Voe voltage value, then subtract the theoretical accuracy G_th*In, and finally divide by V_FS (rated output voltage). Here, In is the current being tested. G_th is the gain at room temperature, which refers to the output voltage of the product corresponding to 1A current at room temperature, and different gains can be set according to specific requirements or application scenarios.

[0085] The detection device of the present application can detect direct current with a large range (450A). By adjusting magnetic core parameters such as air gap size, current detection with an even larger range, such as 700A or even higher, can be achieved.

[0086] In summary, in the direct current and arc current detection device of the present application, the wire of the current to be measured passes through the magnetic core. The magnetic core generates a corresponding magnetic field at the air gap in response to the current flowing through the wire of the current to be measured. When the magnetic sensing chip senses the magnetic field at the air gap, a corresponding target signal is generated and transmitted to the first signal processing module. On the one hand, the first signal processing module generates a feedback current corresponding to the magnitude of the magnetic field at the air gap to supply to the feedback coil, so that the feedback coil generates an induced magnetic field to cancel the magnetic field at the air gap. On the other hand, the first signal processing module processes the target signal generated by the magnetic sensing chip and transmits it to the second signal processing module, so that after the second signal processing module amplifies and filters the target signal, the arc signal and the direct current signal are respectively identified and output. The above device can keep the magnetic field at the air gap balanced, and further make the change amplitude of the magnetic field at the air gap small and the change frequency fast with respect to the change of the wire of the current to be measured, having good followability and extremely fast step response time, thereby improving the detection accuracy of the direct current and arc current detection device.

[0087] Figure 4 is a schematic structural diagram of a DC and arc current detection device shown according to an exemplary embodiment. As Figure 4 shown, on the basis of the device shown in Figure 1 shown, the device further includes a self-check module, and the self-check module in the device includes a self-check circuit 112 and a self-check coil 111.

[0088] The self-check coil 111 is wound around the magnetic core 101; the first end of the self-check coil 111 is grounded; the second end of the self-check coil is connected to the self-check circuit 112;

[0089] The self-check circuit 112 is used to provide a self-check current for the self-check coil 111.

[0090] When the self-check circuit 112 is started, the magnetic sensing chip 104 is used to detect the magnetic field generated by the self-check coil 111 and generate a corresponding self-check signal for processing through the first signal processing module 105 and the second signal processing module 106.

[0091] Figure 5 shows a circuit structure diagram of a self-check circuit according to an embodiment of the present application. As Figure 5 shown, the self-check circuit includes a first self-check diode D5, a second self-check diode D6, a first self-check resistor R29, a second self-check resistor R28, a third self-check resistor R30, a zener diode U4, and a self-check triode Q5;

[0092] In the self-check circuit, the collector of the self-check triode Q5 is connected to the power supply voltage terminal VCC through the first self-check resistor R29;

[0093] The base of the self-check triode Q5 is connected to the trigger pin CHK of the self-check module through the second self-check resistor R28; the trigger pin CHK is connected to the negative electrode of the first self-check diode D5; the positive electrode of the first self-check diode D5 is grounded; the base of the self-check triode Q5 is also connected to the negative electrode of the zener diode U4; the positive electrode of the zener diode U4 is grounded; the control terminal of the zener diode U4 is connected to the emitter of the self-check triode Q5;

[0094] The emitter of the self-check triode Q5 is also connected to the second end of the self-check coil 111 through the third self-check resistor R30; the emitter of the self-check triode Q5 is also connected to the negative electrode of the second self-check diode D6; the positive electrode of the second self-check diode D6 is grounded.

[0095] In the embodiment of the present application, by inputting an AC signal (with a peak-to-peak value between 3.3V and 5.5V) to the trigger pin CHK, the self-check mode can be started. At this time, the voltage stabilizing diode U4 stabilizes the voltage at Upk = 2.5V. By adjusting the size of the third self-check resistor R30, the size of the self-check current flowing through the self-check coil 111 is set, so that the self-check coil obtains a self-check current.

[0096] After the self-check function is started, after the magnetic field generated by the self-check coil current is sensed by the magnetic sensing chip, the signal output by the magnetic sensing chip is processed by the first signal processing module 105 and the second signal processing module 106 in sequence and then output. By reading the output of AC_Vout, it can be determined whether the problem lies with the sensor itself or the object to be measured. There is no need to disassemble the machine to detect the product performance, and it can be judged whether the detection device is normal on the host computer.

[0097] In summary, in the DC and arc current detection device of the present application, the current-carrying wire to be measured passes through the magnetic core. The magnetic core responds to the current flowing through the current-carrying wire to be measured and generates a corresponding magnetic field at the air gap of the magnetic core. When the magnetic sensing chip senses the magnetic field at the air gap, a corresponding target signal is generated and transmitted to the first signal processing module. On the one hand, the first signal processing module generates a feedback current corresponding to the magnetic field at the air gap to be provided to the feedback coil, so that the feedback coil generates an induced magnetic field to cancel the magnetic field at the air gap. On the other hand, the first signal processing module processes the target signal generated by the magnetic sensing chip and transmits it to the second signal processing module, so that the second signal processing module amplifies and filters the target signal and then respectively identifies the arc signal and the DC signal and outputs them. The above device can keep the magnetic field at the air gap balanced, and further make the magnetic field at the air gap change with a small amplitude and a fast change frequency as the current-carrying wire to be measured changes, having good followability and an extremely fast step response time, thereby improving the detection accuracy of the DC and arc current detection device.

[0098] Those skilled in the art will readily think of other embodiments of the present application after considering the specification and practicing the utility model disclosed herein. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include the common general knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present application are pointed out by the following claims.

[0099] It should be understood that the present application is not limited to the precise structures already described and shown in the drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A DC and arc current detection device, characterized in that: The device comprises: A magnetic core, wherein an air gap is provided on the magnetic core; a current conductor to be measured passes through the magnetic core; a feedback coil, which is wound around a magnetic core; A magnetic sensor chip is placed at a designated position of the magnetic core to sense the magnetic field at the air gap; a first signal processing module, electrically connected to the magnetic sensor chip and the feedback coil respectively; the first signal processing module is used to receive a target signal sent by the magnetic sensor chip, and provide a feedback current to the feedback coil according to the target signal; The second signal processing module is electrically connected to the first signal processing module; the second signal processing module is used to receive the output signal of the first signal processing module and filter the output signal to obtain an AC arcing signal and a DC signal respectively.

2. The device according to claim 1, characterized in that The magnetic sensor chip is placed at the air gap of the magnetic core; Alternatively, the magnetic sensor chip is arranged close to the air gap of the magnetic core.

3. The device according to claim 2, characterized in that The magnetic sensor chip is a TMR chip.

4. The device according to claim 1, characterized in that The first signal processing module includes a first operational amplifier; the input end of the first operational amplifier is used to access the output signal of the magnetic sensor chip; The positive output terminal of the first operational amplifier is connected to the first end of the target resistor through the feedback coil; the second end of the target resistor is connected to the negative output terminal of the first operational amplifier; and the voltage value on the target resistor is transmitted to the second signal processing module as the output signal of the first signal processing module.

5. The device according to claim 4, characterized in that The second signal processing module includes a primary amplification circuit, a filtering circuit and a secondary amplification circuit; The first-stage amplifier circuit is electrically connected to the first signal processing module to receive and amplify the output signal of the first signal processing module to obtain a first amplified signal; the first-stage amplifier circuit is used to output the first amplified signal through the AC / DC output terminal; The filtering circuit is used to receive the first amplified signal and perform filtering processing to obtain an AC signal and transmit it to the secondary amplification circuit; The secondary amplifier circuit is used to receive the AC signal and perform amplification processing to obtain a second amplified signal which is output through the arc output terminal.

6. The device according to claim 5, characterized in that The first-stage amplification circuit includes a second operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor; The positive input terminal of the second operational amplifier is connected to the first end of the target resistor through the first resistor; the negative input terminal of the second operational amplifier is connected to the second end of the target resistor through the second resistor; The positive input terminal of the second operational amplifier is also connected to the output terminal of the second operational amplifier through the third resistor; the negative input terminal of the second operational amplifier is also connected to the output terminal of the second operational amplifier through the fourth resistor; The output end of the second operational amplifier is connected to the AC and DC output ends and the output end of the filter circuit respectively.

7. The device according to claim 6, characterized in that The filtering circuit includes a first capacitor and a second capacitor; the secondary amplification circuit includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor and a third operational amplifier; The first end of the first capacitor is connected to the output end of the second operational amplifier; the first end of the second capacitor is connected to the first reference voltage end; The second end of the first capacitor is connected to the positive input end of the third operational amplifier through a fifth resistor; the positive input end of the third operational amplifier is also connected to the second reference voltage end through a seventh resistor; The second end of the second capacitor is connected to the negative input end of the third operational amplifier through a sixth resistor; the negative input end of the third operational amplifier is also connected to the output end of the third operational amplifier through an eighth resistor; The output terminal of the third operational amplifier is connected to the arc output terminal.

8. The device according to any one of claims 1 to 7, characterized in that: The device also includes a self-test module; the self-test module includes a self-test coil and a self-test circuit; The self-test coil is wound on the magnetic core; the first end of the self-test coil is grounded; the second end of the self-test coil is connected to the self-test circuit; The self-test circuit is used to provide a self-test current for the self-test coil.

9. The device according to claim 8, characterized in that When the self-test circuit is started, the magnetic sensor chip is used to detect the magnetic field generated by the self-test coil and generate a corresponding self-test signal to be processed by the first signal processing module and the second signal processing module.

10. The device according to claim 8, characterized in that The self-test circuit includes a first self-test diode, a second self-test diode, a first self-test resistor, a second self-test resistor, a third self-test resistor, a voltage stabilizing diode and a self-test transistor; In the self-test circuit, the collector of the self-test transistor is connected to the power supply voltage terminal through a first self-test resistor; The base of the self-test transistor is connected to the trigger pin of the self-test module through the second self-test resistor; the trigger pin is connected to the cathode of the first self-test diode; the anode of the first self-test diode is grounded; the base of the self-test transistor is also connected to the cathode of the voltage-stabilizing diode; the anode of the voltage-stabilizing diode is grounded; the control end of the voltage-stabilizing diode is connected to the emitter of the self-test transistor; The emitter of the self-test transistor is also connected to the second end of the self-test coil through a third self-test resistor; the emitter of the self-test transistor is also connected to the cathode of the second self-test diode; the anode of the second self-test diode is grounded.

Images