CN216352009U - Small signal characteristic current excitation circuit with wide voltage range - Google Patents
Small signal characteristic current excitation circuit with wide voltage range Download PDFInfo
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- CN216352009U CN216352009U CN202123182497.8U CN202123182497U CN216352009U CN 216352009 U CN216352009 U CN 216352009U CN 202123182497 U CN202123182497 U CN 202123182497U CN 216352009 U CN216352009 U CN 216352009U
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Abstract
The utility model discloses a small-signal characteristic current excitation circuit with a wide voltage range, which comprises a microcontroller U4, wherein the controller is electrically connected with an isolation circuit, the isolation circuit is electrically connected with a constant current circuit, the constant current circuit is connected with a rectifying circuit U1, a current-limiting resistor R1 is electrically connected between the constant current circuit and the rectifying circuit, the constant current circuit is connected with a power module, and the rectifying circuit is connected with the power module.
Description
Technical Field
The utility model relates to the field of relay protection of power systems, in particular to a small-signal characteristic current excitation circuit with a wide voltage range.
Background
In the application of an intelligent power grid, the application of low-voltage electric automatic topology recognition is the basis for supporting other applications, and the common characteristic current excitation mode is to realize the conduction between loops by connecting a switch tube into a load. The scheme has lower cost and simple principle; the automatic topology identification mode based on the characteristic current injection mode has high accuracy and high identification speed, and has good application prospect.
However, the existing automatic topology identification mode based on the characteristic current injection mode often has the problem of low success rate of characteristic current identification due to the fact that the amplitude of output characteristic current is small and the characteristic current is easily interfered by field load fluctuation, voltage fluctuation and harmonic current; and the existing topology identification mode generally faces the problems of low circuit safety degree and high power consumption.
SUMMERY OF THE UTILITY MODEL
The utility model aims to overcome the defects of the technology and provide a small-signal characteristic current excitation circuit with a wide voltage range, which has the characteristics of simple and reliable circuit, small volume, low power consumption, low cost and wide voltage range, and can be well adapted to the existing small-current topology identification equipment.
In order to solve the technical problems, the technical scheme adopted by the utility model is as follows:
a small signal characteristic current excitation circuit with a wide voltage range comprises a microcontroller U4, wherein the controller is electrically connected with an isolation circuit, the isolation circuit is electrically connected with a constant current circuit, the constant current circuit is connected with a rectifying circuit U1, a current limiting resistor R1 is electrically connected between the constant current circuit and the rectifying circuit, the constant current circuit is connected with a power supply module, and the rectifying circuit is connected with the power supply module; the constant current circuit comprises an MOS transistor V1, a reference source U2 and a second resistor R2; the drain electrode of the MOS tube V1 is electrically connected with the rectifying circuit U1 through a current-limiting resistor R1, the grid electrode of the MOS tube V1 is divided into two paths, the first path is connected with a reference source U2, the second path is connected with the isolating circuit through a third resistor R3, the source electrode of the MOS tube V1 is divided into two paths, the first path is electrically connected with the reference source U2, the second path is connected with one end of a second resistor R2, the other end of the second resistor R2 is divided into two paths, the first path is grounded, and the second path is electrically connected with the power supply module; the power supply module comprises a diode D1, the anode of the diode D1 is electrically connected with the rectifying circuit, the cathode of the diode D1 is connected with one end of a fifth resistor R5, the other end of the fifth resistor R5 is divided into two paths, the first path is connected with the cathode of a voltage regulator tube Z1, the second path is connected with one end of a capacitor C1, the anode of the voltage regulator tube Z1 is divided into two paths, the first path is electrically connected with the other end of the capacitor C1, and the second path is electrically connected with the constant current circuit.
Furthermore, the gate of the MOS transistor V1 in the constant current circuit is electrically connected to one end of a pull-down resistor R4, and one end of the pull-down resistor R4 is connected to the anode of the reference source U2.
Further, the TXD pin and the RXD pin of the microcontroller U4 transmit and receive data to the external communication, and the IO port of the microcontroller U4 is electrically connected with the isolation circuit.
Further, the isolation circuit comprises an optical coupler U3, and a sixth resistor R6 is arranged between the optical coupler U3 and an IO port of the microcontroller U4.
Further, the model of the reference source U2 is TL431, the model of the MOS tube V1 is LNG4N80, the model of the microcontroller U4 is R5F1026A, and the model of the optocoupler U3 is TLV-816.
The utility model has the beneficial effects that:
1. the circuit provided by the utility model has the characteristics of simplicity, reliability, small volume, low power consumption and low cost, can be used in a wide voltage range, and can be well adapted to the existing low-current topology identification equipment.
2. Through setting up constant current circuit and current-limiting resistor R1, between live wire L and zero line N, when voltage is very high, constant current circuit plays a role, makes the electric current inject in certain extent, and MOS pipe V1 and current-limiting resistor R1 share jointly and generate heat this moment, reduce whole consumption of generating heat, avoid burning out the resistance when voltage is too high, ensure circuit safe and reliable.
3. The two ends of the constant current circuit are connected in parallel with a pull-down resistor R4, and when the rectifying circuit U1 is turned off, the pull-down resistor R4 is used for ensuring that the voltage of the grid electrode of the MOS transistor V1 is consistent with that of the source electrode, so that the MOS transistor V1 is prevented from being switched on mistakenly due to interference.
Drawings
Fig. 1 is a schematic diagram of an overall circuit layout according to an embodiment of the utility model.
Fig. 2 is a schematic diagram of a connection relationship between modules in the embodiment of the present invention.
Detailed Description
The embodiments of the present invention will be further described with reference to the drawings and examples. It should be noted that the examples do not limit the scope of the claimed invention.
Example 1
As shown in fig. 1 to 2, the small-signal characteristic current excitation circuit with a wide voltage range comprises a microcontroller U4, wherein the controller is electrically connected with an isolation circuit, the isolation circuit is electrically connected with a constant current circuit, the constant current circuit is connected with a rectification circuit U1, a current-limiting resistor is electrically connected between the constant current circuit and the rectification circuit, the constant current circuit is connected with a power supply module, and the rectification circuit is connected with the power supply module.
The TXD pin and the RXD pin of the microcontroller U4 transmit and receive data to external communication, and the IO port of the microcontroller U4 is electrically connected with the isolation circuit. The external communication sends a command to the microcontroller U4 to initiate the topology signaling.
The isolation circuit comprises a sixth resistor R6 electrically connected with an IO port of the microcontroller U4, and an optical coupler U3 is connected to the sixth resistor R6.
The constant current circuit comprises an MOS transistor V1, a reference source U2 and a second resistor R2; the drain electrode of the MOS tube V1 is electrically connected with the rectifying circuit U1 through a current-limiting resistor R1, the grid electrode of the MOS tube V1 is divided into two paths, the first path is connected with the cathode of a reference source U2, the second path is connected with an isolating circuit through a third resistor R3, the source electrode of the MOS tube V1 is divided into two paths, the first path is electrically connected with the reference electrode of the reference source U2, the second path is connected with one end of a second resistor R2, the other end of the second resistor R2 is divided into two paths, the first path is grounded, and the second path is electrically connected with the power module; the anode of the reference source U2 is connected with a power supply GND point, and each pin of the rectifying circuit U1 is respectively connected with a power supply VCC, a zero line N, a live line L and ground.
The current limiting resistor R1 is used for adjusting the topology identification current signal, and its resistance value is R ═ U/I, and wherein U is the voltage between live wire L and zero line N, and I is predetermined current value, when generally carrying out topology identification, carries out analysis and judgement by the size of the characteristic current value of identification module detection live wire L and zero line N, therefore I can not be too little, generally fixes the minimum value of I as 200 mA. When the topology identification current value is constant, the resistance value of the current limiting resistor R1 is also constant.
The second resistor R2 detects a current signal, and when the voltage between the live line L and the neutral line N increases, the current flowing through the loop increases accordingly, and the voltage at R2 also increases accordingly, if the loop resistance does not change. When the current of the loop is increased, the voltage of the reference source U2 and the voltage of the MOS tube V1 are changed, so that the MOS tube V1 is in an amplification state, the on-resistance of the MOS tube V1 is changed, the current of the circuit is constant, and the generated power consumption is shared by the current limiting resistor R1 and the MOS tube V1. The function of the reference source U2 is that when the voltage of the reference electrode is lower than the equilibrium point by 2.5V, the cathode voltage is not controlled, and when the voltage of the reference electrode is higher than 2.5V, the cathode voltage is controlled, so as to control the gate of the MOS transistor V1, so that the MOS transistor V1 is in a dynamic adjustment state, that is, an amplification state, at this time, the on-resistance of the MOS transistor V1 is relatively large, so as to limit the loop current, and reduce the voltage of the R2, thereby achieving the equilibrium point of 2.5V.
The power module comprises a diode D1, a fifth resistor R5, a voltage regulator tube Z1 and a capacitor C1, and is used for providing a grid starting voltage when the MOS tube V1 is conducted. The voltage stabilizing range of the power supply module is 5-12V. The anode of the diode D1 is electrically connected with the rectifying circuit, the cathode of the diode D1 is connected with one end of a fifth resistor R5, the other end of the fifth resistor R5 is divided into two paths, the first path is connected with the cathode of a voltage regulator tube Z1, the second path is connected with one end of a capacitor C1, the anode of the voltage regulator tube Z1 is divided into two paths, the first path is electrically connected with the other end of the capacitor C1, and the second path is electrically connected with the constant current circuit.
The grid electrode of a MOS transistor V1 in the constant current circuit is electrically connected with one end of a pull-down resistor R4, and one end of a pull-down resistor R4 is connected with the anode of a reference source U2. When the rectifying circuit U1 is turned off, the pull-down resistor R4 is used for ensuring that the voltage of the grid electrode of the MOS transistor V1 is consistent with that of the source electrode, and the phenomenon that the MOS transistor V1 is switched on mistakenly due to interference is avoided.
The microcontroller U4 outputs high and low pulse signals with specific duty ratio, specific frequency and specific time length to the isolation circuit through an IO port according to the requirement of a coding rule, the high and low pulse signals with specific duty ratio, specific frequency and specific time length output by the microcontroller U4 are isolated and transmitted to the MOS tube V1 in the constant current circuit through the optical coupler U3, and the MOS tube V1 is controlled to be switched on and off according to the frequency, duty ratio and time, so that a small current signal waveform with specific frequency, duty ratio and time length is generated on the live wire L and the zero wire N, and the signal waveform can be analyzed by the topology identification module to obtain the topology information of a specific transformer area.
When the voltage between the live line L and the neutral line N is low, the characteristic current is small at this time. The constant current circuit does not work, the MOS tube V1 works in a saturation state, therefore, the heating power consumption is the current-limiting resistor R1, when the voltage is very high, the constant current circuit works, the current is limited in a certain range, and at the moment, the MOS tube V1 and the current-limiting resistor R1 share the heating. The whole heating power consumption is reduced, the resistor is prevented from being burnt when the voltage is too high, and the safety and the reliability of the circuit are ensured.
The reference model of the reference source U2 is TL431, the model of the MOS tube V1 is LNG4N80, the model of the microcontroller U4 is R5F1026A, and the model of the optocoupler U3 is TLV-816.
Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.
Claims (6)
1. A small signal characteristic current excitation circuit with a wide voltage range is characterized by comprising a microcontroller (U4), wherein the controller is electrically connected with an isolation circuit, the isolation circuit is electrically connected with a constant current circuit, the constant current circuit is connected with a rectification circuit (U1), a current limiting resistor (R1) is electrically connected between the constant current circuit and the rectification circuit, the constant current circuit is connected with a power supply module, and the rectification circuit is connected with the power supply module; the constant current circuit comprises an MOS (metal oxide semiconductor) tube (V1), a reference source (U2) and a second resistor (R2); the drain electrode of the MOS tube (V1) is electrically connected with the rectifying circuit (U1) through a current-limiting resistor (R1), the grid electrode of the MOS tube (V1) is divided into two paths, the first path is connected with a reference source (U2), the second path is connected with the isolating circuit through a third resistor (R3), the source electrode of the MOS tube (V1) is divided into two paths, the first path is electrically connected with the reference source (U2), the second path is connected with one end of the second resistor (R2), the other end of the second resistor (R2) is divided into two paths, the first path is grounded, and the second path is electrically connected with the power module; the power supply module comprises a diode (D1), the positive electrode of the diode (D1) is electrically connected with the rectifying circuit, the negative electrode of the diode (D1) is connected with one end of a fifth resistor (R5), the other end of the fifth resistor (R5) is divided into two paths, the first path is connected with the negative electrode of a voltage regulator tube (Z1), the second path is connected with one end of a capacitor (C1), the positive electrode of the voltage regulator tube (Z1) is divided into two paths, the first path is electrically connected with the other end of the capacitor (C1), and the second path is electrically connected with the constant current circuit.
2. The small-signal characteristic current excitation circuit with the wide voltage range according to claim 1, wherein the gate of the MOS transistor (V1) in the constant current circuit is electrically connected with one end of a pull-down resistor (R4), and one end of the pull-down resistor (R4) is connected with the anode of a reference source (U2).
3. The small-signal characteristic current excitation circuit with the wide voltage range according to claim 1, wherein the TXD pin and the RXD pin of the microcontroller (U4) transmit and receive data to and from external communication, and the IO port of the microcontroller (U4) is electrically connected with the isolation circuit.
4. The small-signal characteristic current excitation circuit with the wide voltage range according to claim 3, wherein the isolation circuit comprises an optical coupler (U3), and a sixth resistor (R6) is arranged between the optical coupler (U3) and an IO port of the microcontroller (U4).
5. The small-signal characteristic current excitation circuit with the wide voltage range according to claim 1, wherein the reference source (U2) has a reference model of TL431, and the MOS transistor (V1) has a model of LNG4N 80.
6. The small-signal characteristic current excitation circuit with the wide voltage range according to claim 4, wherein the microcontroller (U4) is of the type R5F1026A, and the optocoupler (U3) is of the type TLV-816.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123182497.8U CN216352009U (en) | 2021-12-17 | 2021-12-17 | Small signal characteristic current excitation circuit with wide voltage range |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123182497.8U CN216352009U (en) | 2021-12-17 | 2021-12-17 | Small signal characteristic current excitation circuit with wide voltage range |
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| Publication Number | Publication Date |
|---|---|
| CN216352009U true CN216352009U (en) | 2022-04-19 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202123182497.8U Active CN216352009U (en) | 2021-12-17 | 2021-12-17 | Small signal characteristic current excitation circuit with wide voltage range |
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| CN (1) | CN216352009U (en) |
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2021
- 2021-12-17 CN CN202123182497.8U patent/CN216352009U/en active Active
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Address after: 411201 28 Bai Shi Road, Jing Kai District, Xiangtan, Hunan Patentee after: Weisheng Energy Technology Co.,Ltd. Address before: 411201 28 Bai Shi Road, Jing Kai District, Xiangtan, Hunan Patentee before: WASION ELECTRIC Co.,Ltd. |
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