Current sampling circuit, current sampling device and circuit breaker
By designing a current sampling circuit including a current transformer, the first and second sampling circuits, and controlling the operation of the sampling circuit according to the current value, the problem of poor compatibility of the current sampling circuit in the prior art is solved, and accurate and fast sampling of different currents is achieved.
Patent Information
- Application Number
- CN202421847624.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-31
- Publication Date
- 2025-07-22
- Estimated Expiration
- 2034-07-31
AI Technical Summary
The current sampling circuit in the prior art cannot take into account both the accurate sampling of large current and small current, resulting in poor compatibility.
The current sampling circuit design is adopted, including a current transformer, a first sampling circuit, a second sampling circuit and a sampling control circuit, and the operation of the first and second sampling circuits is controlled according to the magnitude of the current value, and samples are respectively performed for different current values.
Accurate and fast sampling of currents of different sizes is achieved, and the compatibility and sampling accuracy of current sampling circuits are improved.
Smart Images
Figure CN223139696U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electronic technologies, and in particular, to a current sampling circuit, a current sampling device, and a circuit breaker. Background Art
[0002] In the field of circuit breakers, in order to protect the circuit from damage, it is necessary to collect and monitor the current value in the circuit, so as to open the circuit loop in time when the current is too large, so as to protect the devices in the circuit from being damaged by the impact of large current.
[0003] In the related art, when sampling the current value in a circuit breaker, a single current sampling circuit is used to sample the current value in the circuit. Then, since the magnitude of the current value in the circuit often changes, a single current sampling circuit usually cannot take into account the accurate sampling of different current values at the same time. For example, if the current sampling circuit of the circuit is configured to have higher sampling accuracy and sampling efficiency when the current value is large, then when the current value in the circuit changes to a small value, the sampling accuracy and sampling efficiency of the current sampling circuit will decrease. Therefore, the current sampling circuit in the related art has poor compatibility when sampling different current values and there is still room for improvement. Summary of the Utility Model
[0004] This application provides a current sampling circuit, a current sampling device, and a circuit breaker to solve the technical problem that the current sampling circuit in the related art has poor compatibility when sampling different current values.
[0005] In a first aspect, this application provides a current sampling circuit, including: a current transformer, a first sampling circuit, a second sampling circuit, and a sampling control circuit;
[0006] Wherein, the input end of the current transformer is connected to the line to be measured, and the output end of the current transformer is respectively connected to the sampling ends of the first sampling circuit and the second sampling circuit;
[0007] At least one of the first sampling circuit and the second sampling circuit includes a transistor, or a transistor is provided on the output end of the current transformer; the input end of the sampling control circuit is connected to the output end of the self-power supply circuit in the current transformer, and the output end of the sampling control circuit is connected to the transistor;
[0008] The sampling control circuit is configured to output a corresponding switch control signal according to the current value in the line to be measured, and the switch control signal is used to control the conduction or cutoff of the transistor, so as to control the conduction of at least one of the first sampling circuit and the second sampling circuit to sample the current value in the line to be measured;
[0009] The first sampling circuit is configured to collect the current value when the current value in the to-be-tested line is greater than the current threshold, and convert the current value into a first voltage value; the second sampling circuit is configured to collect the current value when the current value in the to-be-tested line is less than the current threshold, and convert the current value into a second voltage value.
[0010] In some possible designs, the first sampling circuit includes a first resistor, a second resistor, a third resistor, a first capacitor, and a first operational amplifier;
[0011] The first end of the first resistor is the sampling end of the first sampling circuit, the second end of the first resistor is connected to the first end of the second resistor, the second end of the second resistor is connected to the inverting input terminal of the first operational amplifier, the first end of the first capacitor is connected to the second end of the first resistor, and the second end of the first capacitor is grounded;
[0012] The non-inverting input terminal of the first operational amplifier is grounded; the second end of the second resistor is connected to the first end of the third resistor, and the second end of the third resistor is connected to the output terminal of the first operational amplifier.
[0013] In some possible designs, the first sampling circuit further includes a fourth resistor and a second capacitor;
[0014] The output terminal of the first operational amplifier is connected to the first end of the fourth resistor, and the second end of the fourth resistor is the output end of the first sampling circuit; the second end of the fourth resistor is connected to the first end of the second capacitor, and the second end of the second capacitor is grounded.
[0015] In some possible designs, the second sampling circuit includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a third capacitor, a fourth capacitor, and a second operational amplifier;
[0016] The first end of the fifth resistor is the first sampling end of the second sampling circuit, the second end of the fifth resistor is connected to the first end of the seventh resistor, the second end of the seventh resistor is connected to the inverting input terminal of the second operational amplifier, the first end of the sixth resistor is the second sampling end of the second sampling circuit, the second end of the sixth resistor is connected to the first end of the eighth resistor, and the second end of the eighth resistor is connected to the non-inverting input terminal of the second operational amplifier; the second end of the fifth resistor is further connected to the first end of the third capacitor, and the second end of the third capacitor is grounded; the second end of the sixth resistor is further connected to the first end of the fourth capacitor, and the second end of the fourth capacitor is grounded;
[0017] The second end of the seventh resistor is also connected to the first end of the ninth resistor. The second end of the ninth resistor is connected to the output end of the second operational amplifier. The second end of the eighth resistor is also connected to the first end of the tenth resistor. The second end of the tenth resistor is used to receive a reference voltage signal.
[0018] In some possible designs, the second sampling circuit further includes an eleventh resistor and a fifth capacitor;
[0019] The first end of the eleventh resistor is connected to the output end of the second operational amplifier. The second end of the eleventh resistor is the output end of the second sampling circuit. The second end of the eleventh resistor is also connected to the first end of the fifth capacitor. The second end of the fifth capacitor is grounded.
[0020] In some possible designs, the sampling control circuit includes a twelfth resistor, a thirteenth resistor, a voltage detector, a sixth capacitor, and a zener diode;
[0021] The negative pole of the zener diode is the input end of the sampling control circuit. The positive pole of the zener diode is connected to the input end of the voltage detector. The positive pole of the zener diode is also connected to the first end of the thirteenth resistor. The second end of the thirteenth resistor is grounded. The sixth capacitor is connected in parallel across the two ends of the thirteenth resistor;
[0022] The output end of the voltage detector is connected to the first end of the twelfth resistor. The second end of the twelfth resistor is the output end of the sampling control circuit for outputting the switch control signal.
[0023] In some possible designs, the current transformer includes multiple groups of output ends. Among them, each group of output ends includes an output positive pole and an output negative pole;
[0024] The current sampling circuit includes multiple groups of sampling circuits. Among them, each group of sampling circuits includes one of the first sampling circuits and a second sampling circuit;
[0025] Among them, one group of sampling circuits corresponds to one group of output ends on the current transformer. And the sampling end of the first sampling circuit is connected to the output positive pole. The first sampling end and the second sampling end of the second sampling circuit are respectively connected to the output positive pole and the output negative pole.
[0026] In some possible designs, a transistor is provided on the output negative pole of each group of output ends in the current transformer. The control pole of the transistor is connected to the output end of the sampling control circuit.
[0027] In a second aspect, the present application further provides a current sampling device. The current sampling device includes the current sampling circuit as described above.
[0028] In a third aspect, the present application also provides a circuit breaker, which includes the current sampling circuit as described above.
[0029] Through the current sampling circuit provided in the first aspect above, a first sampling circuit and a second sampling circuit are respectively set according to the magnitude of the sampled current. During the working process, the corresponding sampling circuit can be controlled according to the magnitude of the current value to achieve accurate and rapid sampling of the current value.
[0030] For what is provided in the second aspect above and each possible design of the second aspect, the beneficial effects can be referred to the beneficial effects brought by the first aspect and each possible implementation manner of the first aspect, which will not be elaborated here. Description of the Drawings
[0031] Figure 1 It is a schematic structural diagram of a current sampling circuit provided by an embodiment of the present application;
[0032] Figure 2 It is a schematic structural diagram of the first sampling circuit provided by an embodiment of the present application;
[0033] Figure 3 It is a schematic structural diagram of the second sampling circuit provided by an embodiment of the present application;
[0034] Figure 4 It is a schematic structural diagram of the sampling control circuit provided by an embodiment of the present application;
[0035] Figure 5 It is a schematic structural diagram of a group of output terminals in the current transformer provided by an embodiment of the present application;
[0036] Figure 6 It is one of the schematic structural diagrams of multiple groups of output terminals in the current transformer provided by an embodiment of the present application;
[0037] Figure 7 It is the second of the schematic structural diagrams of multiple groups of output terminals in the current transformer provided by an embodiment of the present application.
[0038] Reference Signs: 10 - current transformer, 20 - sampling control circuit, 30 - current sampling module, 31 - first sampling circuit, 32 - second sampling circuit, 40 - microprocessor. Detailed Embodiments
[0039] In this application, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship. "At least one of the following" or its similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, at least one of a alone, b alone, or c alone can represent: a alone, b alone, c alone, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b, and c, where a, b, and c can be single or multiple. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0040] The orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "upper", "lower", "left", "right", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application.
[0041] The terms "connected" and "coupled" should be understood in a broad sense. For example, the "connection" or "coupling" of a circuit structure can refer not only to a physical connection but also to an electrical connection or a signal connection. For example, it can be a direct connection, i.e., a physical connection, or it can be indirectly connected through at least one intermediate element, as long as the circuit is connected. It can also be the connection inside two elements; a signal connection can refer not only to a signal connection through a circuit but also to a signal connection through a media medium, such as radio waves. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0042] The transistors in this application are three-terminal transistors, and its three terminals are the control electrode, the first electrode, and the second electrode. The transistor can be a bipolar transistor or a field-effect transistor, etc. For example, when the transistor is a bipolar transistor, its control electrode refers to the base of the bipolar transistor, the first electrode can be the collector or emitter of the bipolar transistor, and the corresponding second electrode can be the emitter or collector of the bipolar transistor; when the transistor is a field-effect transistor, its control electrode refers to the gate of the field-effect transistor, the first electrode can be the drain or source of the field-effect transistor, and the corresponding second electrode can be the source or drain of the field-effect transistor.
[0043] In the related art, when sampling the current value in a circuit, a current sampling circuit is generally set up to collect the current value in the circuit. However, a single current sampling circuit usually cannot simultaneously meet the accurate sampling of large currents and small currents, resulting in poor compatibility of the current sampling circuit in the related art.
[0044] To overcome the technical defects in the above related art, the present application provides a current sampling circuit, which includes: a current transformer, a first sampling circuit, a second sampling circuit, and a sampling control circuit; the output end of the current transformer is respectively connected to the sampling ends of the first sampling circuit and the second sampling circuit, and the sampling control circuit can control one of the first sampling circuit and the second sampling circuit to work according to the current value in the circuit. The first sampling circuit and the second sampling circuit respectively sample different magnitudes of current values in the circuit, so as to ensure that the current sampling circuit can be compatible with different magnitudes of current for sampling, and ensure the sampling accuracy and sampling speed.
[0045] Figure 1 For a schematic structural diagram of a current sampling circuit provided by an embodiment of the present application, please refer to Figure 1 As shown, the current sampling circuit includes: a current transformer 10, a first sampling circuit 31, a second sampling circuit 32, and a sampling control circuit 20.
[0046] Among them, the input end of the current transformer 10 is connected to the line to be measured. Usually, the current transformer 10 is arranged on the line to be measured, and the current value on the line to be measured is collected through the principle of electromagnetic induction. The output end of the current transformer 10 is respectively connected to the sampling ends of the first sampling circuit 31 and the second sampling circuit 32; the output ends of the first sampling circuit 31 and the second sampling circuit 32 are connected to the ADC sampling pins on the microprocessor 40.
[0047] Among them, at least one of the first sampling circuit 31 and the second sampling circuit 32 includes a transistor, or a transistor is provided on the output end of the current transformer 10; the input end of the sampling control circuit 20 is connected to the output end of the self-power supply circuit ( Figure 1 not shown in the figure) in the current transformer 10. The input end of the self-power supply circuit is generally also connected to the current output end of the current transformer 10, and is used to convert the current signal output by the current transformer 10 into a voltage signal to supply power to each chip in the circuit. Since the self-power supply circuit is a conventional circuit in the current transformer 10, it will not be elaborated here.
[0048] Among them, the output end of the sampling control circuit 20 is connected to the control electrode of the above transistor. In this embodiment, the input end of the sampling control circuit 20 is connected to the output end of the self-generated power supply circuit in the current transformer 10. The output end of the self-generated power supply circuit outputs a voltage value, and this voltage value is related to the magnitude of the current value in the line to be measured. For example, if the current value in the line to be measured is relatively large, the voltage value at the output end of the self-generated power supply circuit is relatively high; if the current value in the line to be measured is relatively small, the voltage value at the output end of the self-generated power supply circuit is relatively low. In this way, the sampling control circuit 20 can sample the magnitude of the current value on the line to be measured. The sampling control circuit 20 is used to output a corresponding switch control signal according to the magnitude of the current value in the line to be measured, and the switch control signal is used to control the conduction or cutoff of the corresponding transistor, so as to control the conduction of the first sampling circuit 31 or the second sampling circuit 32 to sample the current value in the line to be measured.
[0049] Among them, in this embodiment, according to the sampling characteristics when the current value is different, the first sampling circuit 31 and the second sampling circuit 32 are respectively designed to sample different current values. For example, the first sampling circuit 31 is used to collect the current value in the line when the current value in the line to be measured is greater than the current threshold, and convert the collected current value into a first voltage value; the second sampling circuit 32 is used to collect the current value in the line when the current value in the line to be measured is less than the current threshold, and convert the collected current value into a second voltage value.
[0050] It can be understood that the first sampling circuit 31 and the second sampling circuit 32 are equivalent to forming a current sampling module 30, and the sampling control circuit 20 controls one of the sampling circuits in the current sampling module 30 to work according to the magnitude of the current value to complete current sampling.
[0051] Specifically, the transistor in this embodiment can be a switching transistor. The output end of the sampling control circuit 20 is connected to the control electrode of the transistor, and the conduction or cutoff of the corresponding transistor is controlled by the switch control signal output by the sampling control circuit 20.
[0052] In one embodiment, in order to control one of the first sampling circuit 31 and the second sampling circuit 32 to work, transistors can be respectively arranged in the first sampling circuit 31 and the second sampling circuit 32. In this way, the sampling control circuit 20 can output corresponding switch control signals according to the magnitude of the current value to select and control the conduction of the first sampling circuit 31 or the second sampling circuit 32, so as to achieve current sampling.
[0053] In one embodiment, since the first sampling circuit 31 and the second sampling circuit 32 are respectively connected to the output terminal of the current transformer 10, in order to control one of the first sampling circuit 31 and the second sampling circuit 32 to work, a transistor can be provided at the output terminal of the current transformer 10 connected to the first sampling circuit 31, and at the same time, a transistor can also be provided at the output terminal of the current transformer 10 connected to the second sampling circuit 32. In this way, the sampling control circuit 20 can output corresponding switch control signals according to the magnitude of the current value to select and control the first sampling circuit 31 or the second sampling circuit 32 to conduct, thereby realizing current sampling.
[0054] It can be seen that according to the current sampling circuit provided by this embodiment, the first sampling circuit 31 and the second sampling circuit 32 are respectively provided for the magnitude of the sampled current. During the working process, the corresponding sampling circuit can be controlled according to the magnitude of the current value to achieve accurate and fast sampling of the current value.
[0055] In this embodiment, since the sampling difficulty is relatively low when the current value is large, the first sampling circuit 31 can be set as a current sampling circuit with a single input terminal. When the current value is small, in order to improve the sampling accuracy, differential signals can be used to realize current sampling. Therefore, the sampling terminals of the second sampling circuit 32 can include two sampling terminals.
[0056] Generally, the current transformer includes multiple groups of output terminals. Among them, each group of output terminals includes a positive output terminal and a negative output terminal. In this embodiment, the sampling terminal of the first sampling circuit 31 can be connected to the positive output terminal, and the two sampling terminals of the second sampling circuit 32 are respectively connected to the positive output terminal and the negative output terminal to form a differential signal. Since the differential signal has stability, it ensures that there is no distortion during the current value sampling process, thereby ensuring the sampling accuracy.
[0057] Figure 2 For the structural schematic diagram of the first sampling circuit provided by the embodiment of the present application, please refer to Figure 2 As shown, the first sampling circuit 31 includes a first resistor R1, a second resistor R2, a third resistor R3, a first capacitor C1, and a first operational amplifier U1. Among them, the first end of the first resistor R1 is the sampling terminal of the first sampling circuit 31. The second end of the first resistor R1 is connected to the first end of the second resistor R2. The second end of the second resistor R2 is connected to the inverting input terminal of the first operational amplifier U1. The first end of the first capacitor C1 is connected to the second end of the first resistor R1. The second end of the first capacitor C1 is grounded. The non-inverting input terminal of the first operational amplifier U1 is grounded. The second end of the second resistor R2 is connected to the first end of the third resistor R3. The second end of the third resistor R3 is connected to the output terminal of the first operational amplifier U1.
[0058] Among them, the first resistor R1 and the first capacitor C1 form a filtering circuit. The current signal output by the current transformer 10 is converted into a voltage signal through the resistor and then input to the sampling terminal of the first sampling circuit 31. Then, it passes through the above filtering circuit and finally passes through the amplification process of the first operational amplifier U1 to output a corresponding voltage signal.
[0059] In some embodiments, the first sampling circuit 31 further includes a fourth resistor R4 and a second capacitor C2; the output terminal of the first operational amplifier U1 is connected to the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is the output terminal of the first sampling circuit 31; the second end of the fourth resistor R4 is connected to the first end of the second capacitor C2, and the second end of the second capacitor C2 is grounded. The fourth resistor R4 and the second capacitor C2 also form a filtering circuit, which is used to filter the voltage signal output by the first operational amplifier U1 and then output it to the ADC sampling pin of the microprocessor 40.
[0060] Figure 3 For the schematic diagram of the second sampling circuit structure provided by the embodiments of the present application, please refer to Figure 3 As shown, in some embodiments, the second sampling circuit 32 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a third capacitor C3, a fourth capacitor C4, and a second operational amplifier U2. The first end of the fifth resistor R5 is the first sampling terminal of the second sampling circuit 32, the second end of the fifth resistor R5 is connected to the first end of the seventh resistor R7, and the second end of the seventh resistor R7 is connected to the inverting input terminal of the second operational amplifier U2. The first end of the sixth resistor R6 is the second sampling terminal of the second sampling circuit 32, the second end of the sixth resistor R6 is connected to the first end of the eighth resistor R8, and the second end of the eighth resistor R8 is connected to the non-inverting input terminal of the second operational amplifier U2; the second end of the fifth resistor R5 is also connected to the first end of the third capacitor C3, and the second end of the third capacitor C3 is grounded to GND; the second end of the sixth resistor R6 is also connected to the first end of the fourth capacitor C4, and the second end of the fourth capacitor C4 is grounded to GND.
[0061] Among them, the second end of the seventh resistor R7 is also connected to the first end of the ninth resistor R9, the second end of the ninth resistor R9 is connected to the output terminal of the second operational amplifier U2, the second end of the eighth resistor R8 is also connected to the first end of the tenth resistor R10, and the second end of the tenth resistor R10 is used to receive the reference voltage signal Vref, and the reference voltage signal Vref is specifically set according to the voltage value in the circuit, which will not be elaborated here.
[0062] In this embodiment, the first sampling terminal and the second sampling terminal are used to collect the voltage signals on the positive electrode and the negative electrode of the output terminal to form a differential signal. The fifth resistor R5 and the third capacitor C3 form a low-pass filter circuit, and the sixth resistor R6 and the fourth capacitor C4 form a low-pass filter circuit. This low-pass filter circuit is used to filter the collected voltage signals. The seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10, and the second operational amplifier U2 form a differential operational amplifier circuit to condition and amplify the collected signals, and then output them to the ADC sampling pin of the microprocessor 40.
[0063] In some embodiments, the second sampling circuit 32 further includes an eleventh resistor R11 and a fifth capacitor C5; the first end of the eleventh resistor R11 is connected to the output end of the second operational amplifier U2, the second end of the eleventh resistor R11 is the output end of the second sampling circuit 32, the second end of the eleventh resistor R11 is also connected to the first end of the fifth capacitor C5, and the second end of the fifth capacitor C5 is grounded to GND. The eleventh resistor R11 and the fifth capacitor C5 form a filter circuit for filtering the voltage signal output by the second operational amplifier U2.
[0064] Figure 4 For the structural schematic diagram of the sampling control circuit provided by the embodiments of the present application, please refer to Figure 4 As shown, in some embodiments, the sampling control circuit 20 includes a twelfth resistor R12, a thirteenth resistor R13, a voltage detector U3, a sixth capacitor C6, and a zener diode D1. Among them, the negative electrode of the zener diode D1 is the input end of the sampling control circuit 20, and the negative electrode of the zener diode D1 is connected to the power supply terminal of the self-generated power supply circuit in the current transformer 10. The positive electrode of the zener diode D1 is connected to the input end Vin of the voltage detector U3, the positive electrode of the zener diode D1 is also connected to the first end of the thirteenth resistor R13, the second end of the thirteenth resistor R13 is grounded to GND, and the sixth capacitor C6 is connected in parallel across the thirteenth resistor R13; the output end Vout of the voltage detector U3 is connected to the first end of the twelfth resistor R12, and the second end of the twelfth resistor R12 is the output end of the sampling control circuit 20 for outputting a switch control signal SW.
[0065] In this embodiment, the self-powered circuit in the current transformer 10 outputs a supply voltage Vself of about 12V. The zener diode D1 operates in the reverse breakdown region. At this time, the voltage drop of the zener diode D1 is 6.2V. Then, a voltage of 5.8V acts on the input terminal Vin of the voltage detector U3. The voltage detector U3 can be a voltage detector of model ME2807A45M3G. The threshold voltage of this voltage detector U3 is 4.5V. When the current in the line under test is small, the input voltage at the input terminal Vin of the voltage detector U3 is less than 4.5V, and the switching control signal SW output from the output terminal Vout of the voltage detector U3 is at a high level; when the current in the line under test is large, the input voltage at the input terminal Vin of the voltage detector U3 is greater than 4.5V, and the switching control signal SW output from the output terminal Vout of the voltage detector U3 is at a low level.
[0066] In some embodiments, the current transformer 10 includes multiple sets of output terminals. Among them, each set of output terminals includes a positive output terminal and a negative output terminal. The current sampling circuit includes multiple sets of sampling circuits. Among them, each set of sampling circuits includes a first sampling circuit and a second sampling circuit. Among them, one set of sampling circuits corresponds to one set of output terminals on the current transformer 10. Moreover, the sampling terminal of the first sampling circuit is connected to the positive output terminal, and the first sampling terminal and the second sampling terminal of the second sampling circuit are respectively connected to the positive output terminal and the negative output terminal. Among them, a transistor is provided on the negative output terminal of each set of output terminals in the current transformer 10. The control electrode of the transistor is connected to the output terminal of the sampling control circuit 20 to receive the switching control signal SW output therefrom, so as to control the conduction and cut-off of the transistor.
[0067] Figure 5 For the structural schematic diagram of one set of output terminals in the current transformer provided by the embodiment of the present application, please refer to Figure 5 As shown, this output terminal includes a positive output terminal A+ and a negative output terminal A-. The positive output terminal A+ is connected to the first end of the resistor R14. The second end of the resistor R14 is grounded. The negative output terminal A- is connected to the first pole of the transistor Q1. The second pole of the transistor Q1 is connected to the first end of the resistor R15. The second end of the resistor R15 is grounded to GND. The control electrode of the transistor Q1 is grounded through the resistor R16. The first end of the resistor R14 is the sampling point A1, and the first end of the resistor R15 is the sampling point A2. The sampling terminal of the first sampling circuit 31 is connected to the sampling point A1, and the first sampling terminal and the second sampling terminal of the second sampling circuit 32 are respectively connected to the sampling point A1 and the sampling point A2.
[0068] When the current on the circuit to be measured is small, the input voltage at the input terminal Vin of the voltage detector U3 is less than 4.5V. The switch control signal SW output at the output terminal Vout of the voltage detector U3 is at a high level, the transistor Q1 is turned on, and the first sampling terminal and the second sampling terminal of the second sampling circuit 32 respectively collect the differential signals at the sampling points A1 and A2 to output the converted second voltage value. At this time, although the first sampling circuit 31 is still working, the microprocessor 40 takes the second voltage value collected by the second sampling circuit 32 as the standard. When the current on the circuit to be measured is large, the input voltage at the input terminal Vin of the voltage detector U3 is greater than 4.5V. The switch control signal SW output at the output terminal Vout of the voltage detector U3 is at a low level, the transistor Q1 is turned off, the sampling point A2 is disconnected, and the second sampling circuit 32 stops working. At this time, the first sampling circuit 31 samples and outputs the first voltage value to the microprocessor 40.
[0069] It can be seen that according to the current sampling circuit provided in this embodiment, the first sampling circuit 31 and the second sampling circuit 32 are respectively set according to the magnitude of the sampling current. During the working process, the corresponding sampling circuit can be controlled according to the magnitude of the current value to achieve accurate and rapid sampling of the current value.
[0070] Figure 6 It is one of the schematic diagrams of the multi-group output terminal structures in the current transformer provided in the embodiment of the present application. Figure 7 It is the second of the schematic diagrams of the multi-group output terminal structures in the current transformer provided in the embodiment of the present application. Please refer to Figure 6 and Figure 7 As shown, the current transformer 10 includes a group of output terminals A+ and A-, B+ and B-, C+ and C-, and N+ and N-. Among them, the schematic diagrams of the structures of B+ and B-, C+ and C-, and N+ and N- are similar to those of A+ and A-. Corresponding sampling terminals are also provided on each output terminal, which will not be elaborated here.
[0071] Through the above multi-group sampling circuits, current sampling can be simultaneously performed on multiple circuits to be detected, improving the current sampling efficiency.
[0072] Among them, the microprocessor 40 in this embodiment can be a single-chip microcomputer or an MCU (Microcontroller Unit).
[0073] In some embodiments, the present embodiment also provides a current sampling device, which includes the current sampling circuit as described above. The working principle and technical effects of this current sampling device are the same as those of the above current sampling circuit, which will not be elaborated here.
[0074] In some embodiments, the present embodiment further provides a circuit breaker, which includes the current sampling circuit as described above. The working principle and technical effects of this circuit breaker are the same as those in the above current sampling circuit, and will not be elaborated here.
[0075] Finally, it should be noted that the above embodiments are only specific implementation manners of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims
1. A current sampling circuit, characterized in that, Including: A current transformer, a first sampling circuit, a second sampling circuit, and a sampling control circuit; Wherein, the input end of the current transformer is connected to the line to be measured, and the output end of the current transformer is respectively connected to the sampling ends of the first sampling circuit and the second sampling circuit; At least one of the first sampling circuit and the second sampling circuit includes a transistor, or a transistor is provided on the output end of the current transformer; the input end of the sampling control circuit is connected to the output end of the self-power supply circuit in the current transformer, and the output end of the sampling control circuit is connected to the transistor; The sampling control circuit is configured to output a corresponding switch control signal according to the current value in the line to be measured, and the switch control signal is used to control the conduction or cut-off of the transistor, so as to control the conduction of at least one of the first sampling circuit and the second sampling circuit to sample the current value in the line to be measured; The first sampling circuit is configured to collect the current value when the current value in the line to be measured is greater than the current threshold, and convert the current value into a first voltage value; the second sampling circuit is configured to collect the current value when the current value in the line to be measured is less than the current threshold, and convert the current value into a second voltage value.
2. The current sampling circuit according to claim 1, wherein The first sampling circuit includes a first resistor, a second resistor, a third resistor, a first capacitor, and a first operational amplifier; The first end of the first resistor is the sampling end of the first sampling circuit, the second end of the first resistor is connected to the first end of the second resistor, the second end of the second resistor is connected to the inverting input end of the first operational amplifier, the first end of the first capacitor is connected to the second end of the first resistor, and the second end of the first capacitor is grounded; The non-inverting input end of the first operational amplifier is grounded; the second end of the second resistor is connected to the first end of the third resistor, and the second end of the third resistor is connected to the output end of the first operational amplifier.
3. The current sampling circuit according to claim 2, wherein, The first sampling circuit further includes a fourth resistor and a second capacitor; The output end of the first operational amplifier is connected to the first end of the fourth resistor, and the second end of the fourth resistor is the output end of the first sampling circuit; the second end of the fourth resistor is connected to the first end of the second capacitor, and the second end of the second capacitor is grounded.
4. The current sampling circuit according to any one of claims 1 to 3, characterized in that The second sampling circuit includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a third capacitor, a fourth capacitor, and a second operational amplifier; The first end of the fifth resistor is the first sampling end of the second sampling circuit. The second end of the fifth resistor is connected to the first end of the seventh resistor. The second end of the seventh resistor is connected to the inverting input terminal of the second operational amplifier. The first end of the sixth resistor is the second sampling end of the second sampling circuit. The second end of the sixth resistor is connected to the first end of the eighth resistor. The second end of the eighth resistor is connected to the non-inverting input terminal of the second operational amplifier. The second end of the fifth resistor is further connected to the first end of the third capacitor, and the second end of the third capacitor is grounded. The second end of the sixth resistor is further connected to the first end of the fourth capacitor, and the second end of the fourth capacitor is grounded. The second end of the seventh resistor is further connected to the first end of the ninth resistor. The second end of the ninth resistor is connected to the output terminal of the second operational amplifier. The second end of the eighth resistor is further connected to the first end of the tenth resistor. The second end of the tenth resistor is for receiving a reference voltage signal.
5. The current sampling circuit according to claim 4, wherein The second sampling circuit further includes an eleventh resistor and a fifth capacitor. The first end of the eleventh resistor is connected to the output terminal of the second operational amplifier. The second end of the eleventh resistor is the output end of the second sampling circuit. The second end of the eleventh resistor is further connected to the first end of the fifth capacitor, and the second end of the fifth capacitor is grounded.
6. The current sampling circuit according to any one of claims 1-3, characterized in that The sampling control circuit includes a twelfth resistor, a thirteenth resistor, a voltage detector, a sixth capacitor, and a zener diode. The negative electrode of the zener diode is the input end of the sampling control circuit. The positive electrode of the zener diode is connected to the input end of the voltage detector. The positive electrode of the zener diode is further connected to the first end of the thirteenth resistor. The second end of the thirteenth resistor is grounded. The sixth capacitor is connected in parallel across the two ends of the thirteenth resistor. The output end of the voltage detector is connected to the first end of the twelfth resistor. The second end of the twelfth resistor is the output end of the sampling control circuit for outputting the switch control signal.
7. The current sampling circuit according to claim 4, characterized in that The current transformer includes multiple sets of output terminals. Each set of output terminals includes a positive output terminal and a negative output terminal. The current sampling circuit includes multiple sets of sampling circuits. Each set of sampling circuits includes one of the first sampling circuits and one second sampling circuit. One set of sampling circuits corresponds to one set of output terminals on the current transformer. And the sampling end of the first sampling circuit is connected to the positive output terminal, and the first sampling end and the second sampling end of the second sampling circuit are respectively connected to the positive output terminal and the negative output terminal.
8. The current sampling circuit according to claim 7, wherein A transistor is provided on the negative output terminal of each set of output terminals in the current transformer. The control electrode of the transistor is connected to the output end of the sampling control circuit.
9. A current sampling device, characterized in that, Including the current sampling circuit according to any one of claims 1-8.
10. A circuit breaker, characterized in that, Including the current sampling circuit according to any one of claims 1-8.
Citation Information
Cited By
Current acquisition circuit and current acquisition device
CN121276131A