Energy-taking and current-measuring circuit for monitoring operation condition of low-voltage lead of distribution network

Abstract

The utility model relates to an energy taking current measuring circuit for monitoring the operation condition of a distribution network low-voltage lead, which comprises a coil, an energy taking circuit, a bypass switch and a current sampling circuit, the coil is connected with the energy taking circuit, the coil is also connected with the current sampling circuit through the bypass switch, the impedance of the current sampling circuit is smaller than that of the energy taking circuit, and the bypass switch is connected with the current sampling circuit. And the energy taking circuit and the current sampling circuit are switched to work by switching on and switching off the bypass switch. The circuit can realize seamless switching between energy taking and current measurement, and the circuit works stably and reliably.

Description

Technical Field

[0001] The utility model relates to the technical field of distribution network monitoring, and particularly relates to an energy-taking and current-measuring circuit for monitoring the operating conditions of low-voltage conductors in a distribution network. Background Art

[0002] In the monitoring of the operating conditions of low-voltage conductors in a distribution network, there are generally two implementation methods for energy-taking and current sampling through a current monitoring sensor. One is the dual-coil method, that is, independent coils are used for energy-taking and current sampling. This method will increase the size of the sensor, which is not friendly to a compact on-site environment, and will also increase costs. The other is the single-coil method, that is, energy-taking and current sampling are realized through a single coil. This method uses a relay conversion method to switch the mutual inductor to the energy-taking circuit or the current sampling circuit. The problem with this circuit solution is that during the relay conversion process, there is a flying-in-air process. At this time, the mutual inductor coil is open-circuited, and the current source cannot be open-circuited. When open-circuited, the voltage across the mutual inductor will soar, which may cause arcing and damage the relay, and the coil life will also be reduced. Content of the Utility Model

[0003] The purpose of the utility model is to provide an energy-taking and current-measuring circuit for monitoring the operating conditions of low-voltage conductors in a distribution network. This circuit can realize seamless switching between energy-taking and current measurement, and the circuit works stably and reliably.

[0004] To achieve the above purpose, the technical solution adopted by the utility model is: an energy-taking and current-measuring circuit for monitoring the operating conditions of low-voltage conductors in a distribution network, including a coil, an energy-taking circuit, a bypass switch, and a current sampling circuit. The coil is connected to the energy-taking circuit, and the coil is also connected to the current sampling circuit through the bypass switch. The impedance of the current sampling circuit is less than that of the energy-taking circuit. By opening and closing the bypass switch, the operation of the energy-taking circuit and the current sampling circuit is switched.

[0005] Further, the energy-taking circuit includes a bidirectional clamping diode D7, a rectifying diode D4, a unidirectional clamping diode D6, a rectifying diode D5, and an energy storage capacitor C17. The two ends of the coil are connected in parallel with the two ends of the bidirectional clamping diode D7. The unidirectional clamping diode D6, the rectifying diode D5, and the energy storage capacitor C17 are connected in parallel and then connected in series with the rectifying diode D4, and then the whole is connected in parallel with the two ends of the bidirectional clamping diode D7.

[0006] Further, the first connection end of the coil is simultaneously connected to the first connection end of the bidirectional clamping diode D7, the positive electrode of the rectifying diode D4, and the bypass switch. The negative electrode of the rectifying diode D4 is simultaneously connected to the negative electrode of the unidirectional clamping diode D6, the negative electrode of the rectifying diode D5, and the first connection end of the energy storage capacitor C17. The second connection end of the bidirectional clamping diode D7, the positive electrode of the unidirectional clamping diode D6, the positive electrode of the rectifying diode D5, and the second connection end of the energy storage capacitor C17 are simultaneously connected to the second connection end of the coil and grounded.

[0007] Further, the coil induces a current signal, which is rectified by the rectifying diode D4 and stored in the capacitor C17 for external energy supply. The bidirectional clamping diode D7 and the unidirectional clamping diode D6 clamp the voltage to 5.5V.

[0008] Further, the bypass switch uses an optocoupler. The control signal pin of the bypass switch is connected to the control signal CON_SCR1. The two AC signal pins of the bypass switch are respectively connected to the coil and the current sampling circuit. When the control signal CON_SCR1 is pulled high, the optocoupler conducts, and the coil current forms a loop through the current sampling circuit, automatically bypassing the energy extraction circuit.

[0009] Further, the bypass switch uses an MOC3023 optocoupler. Its pin 1 is connected to the control signal CON_SCR1 through a current limiting resistor R1. Pins 2 and 3 are simultaneously grounded. Pin 4 is connected to the coil, and pin 6 is connected to the current sampling circuit.

[0010] Further, the current sampling circuit includes a sampling resistor R19, a first filter resistor R18, a second filter resistor R21, a first filter capacitor C14, a second filter capacitor C15, and a third filter capacitor C16. The first connection end of the sampling resistor R19 is simultaneously connected to the bypass switch and the first connection end of the second filter resistor R21. The second connection end of the sampling resistor R19 is simultaneously connected to the first connection end of the first filter resistor R18 and grounded. The second connection end of the first filter resistor R18 is simultaneously connected to the first connection end of the first filter capacitor C14 and the first connection end of the second filter capacitor C15. The second connection end of the first filter capacitor C14 is connected to the first connection end of the third filter capacitor C16. The second connection end of the second filter resistor R21 is simultaneously connected to the second connection end of the second filter capacitor C15 and the second connection end of the third filter capacitor C16. After the coil is connected to the bypass switch, a loop is formed through the sampling resistor R19. The first filter resistor R18, the second filter resistor R21, the first filter capacitor C14, and the third filter capacitor C16 form a low-pass filter, and the second filter capacitor C15 constitutes a differential mode filter.

[0011] Further, both ends of the second filter capacitor C15 are connected to a metering chip for current calculation.

[0012] Compared with the prior art, the utility model has the following beneficial effects: The utility model provides an energy-taking and current-measuring circuit for monitoring the operating conditions of low-voltage distribution network conductors. This circuit can achieve seamless switching between energy-taking and current measurement. The coil normally operates at the energy-taking circuit end. When sampling is required, it is connected to the current sampling circuit through the bypass method of the electronic switch, and there is no situation of coil open circuit. The circuit works stably and reliably, improving the working life of the circuit. Brief Description of the Drawings

[0013] Figure 1 is the circuit diagram of the energy-taking and current-measuring circuit of the embodiment of the utility model. Detailed Embodiments

[0014] The following further describes the utility model with reference to the drawings and embodiments.

[0015] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0016] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0017] As Figure 1 shown, this embodiment provides an energy-taking and current-measuring circuit for monitoring the operating conditions of low-voltage distribution network conductors, including a coil 1, an energy-taking circuit 2, a bypass switch 3, and a current sampling circuit 4. The coil 1 is connected to the energy-taking circuit 2, and the coil 1 is also connected to the current sampling circuit 4 through the bypass switch 3. The impedance of the current sampling circuit 4 is less than that of the energy-taking circuit 2. By opening and closing the bypass switch 3, the operation of the energy-taking circuit 2 and the current sampling circuit 4 is switched.

[0018] In this embodiment, the energy-taking circuit 2 includes a bidirectional clamping diode D7, a rectifying diode D4, a unidirectional clamping diode D6, a rectifying diode D5, and an energy storage capacitor C17. Both ends of the coil are connected in parallel with both ends of the bidirectional clamping diode D7. After the unidirectional clamping diode D6, the rectifying diode D5, and the energy storage capacitor C17 are connected in parallel, they are connected in series with the rectifying diode D4, and then the whole is connected in parallel with both ends of the bidirectional clamping diode D7.

[0019] Specifically, the first connection end of the coil 1 is simultaneously connected to the first connection end of the bidirectional clamping diode D7, the positive electrode of the rectifier diode D4, and the bypass switch. The negative electrode of the rectifier diode D4 is simultaneously connected to the negative electrode of the unidirectional clamping diode D6, the negative electrode of the rectifier diode D5, and the first connection end of the energy storage capacitor C17. The second connection end of the bidirectional clamping diode D7, the positive electrode of the unidirectional clamping diode D6, the positive electrode of the rectifier diode D5, and the second connection end of the energy storage capacitor C17 are simultaneously connected to the second connection end of the coil 1 and grounded.

[0020] The coil 1 induces a current signal, which is rectified by the rectifier diode D4 and stored in the capacitor C17 for external energy supply, that is, for powering circuits such as the MCU. The bidirectional clamping diode D7 is a bidirectional clamping TVS, and the unidirectional clamping diode D6 is a unidirectional clamping TVS, which clamps the voltage to 5.5V. The rectifier diode D5 can provide a certain leakage current when the energy of the energy extraction circuit is relatively large, reducing the stress on the bidirectional clamping diode D7 and the unidirectional clamping diode D6.

[0021] In this embodiment, the bypass switch 3 consists of a bidirectional AC optocoupler and a control signal. When the control signal CON_SCR1 is pulled high, the bidirectional AC optocoupler conducts, and the coil current forms a loop through the current sampling circuit, automatically bypassing the energy extraction circuit.

[0022] Preferably, the bypass switch 3 uses an optocoupler. The control signal pin of the bypass switch is connected to the control signal CON_SCR1. The control signal CON_SCR1 is sourced from the IO port of the MCU. The two AC signal pins of the bypass switch are respectively connected to the coil and the current sampling circuit. When the control signal CON_SCR1 is pulled high, the optocoupler conducts, and the coil current forms a loop through the current sampling circuit, automatically bypassing the energy extraction circuit. In this embodiment, the bypass switch uses the MOC3023 optocoupler. Its pin 1 is connected to the control signal CON_SCR1 through the current-limiting resistor R1, pins 2 and 3 are simultaneously grounded, pin 4 is connected to the coil, and pin 6 is connected to the current sampling circuit.

[0023] In this embodiment, the current sampling circuit 4 includes a sampling resistor R19, a first filter resistor R18, a second filter resistor R21, a first filter capacitor C14, a second filter capacitor C15, and a third filter capacitor C16. The first connection end of the sampling resistor R19 is simultaneously connected to a bypass switch and the first connection end of the second filter resistor R21. The second connection end of the sampling resistor R19 is simultaneously connected to the first connection end of the first filter resistor R18 and grounded. The second connection end of the first filter resistor R18 is simultaneously connected to the first connection ends of the first filter capacitor C14 and the second filter capacitor C15. The second connection end of the first filter capacitor C14 is connected to the first connection end of the third filter capacitor C16. The second connection end of the second filter resistor R21 is simultaneously connected to the second connection ends of the second filter capacitor C15 and the third filter capacitor C16. The coil 1 forms a loop through the sampling resistor R19 after being connected to the bypass switch, generating a sampling voltage. The first filter resistor R18, the second filter resistor R21, the first filter capacitor C14, and the third filter capacitor C16 form a low-pass filter, and the second filter capacitor C15 constitutes a differential-mode filter. Both ends of the second filter capacitor C15 are connected to a metering chip for current calculation. As Figure 1 shown, IN and IP are differential signals, which are connected to the current sampling pins of the metering chip.

[0024] Most of the time, the coil 1 operates for the energy extraction circuit. At this time, the bypass switch is closed, and the coil 1 forms a loop through the energy extraction circuit, providing electrical energy for the system. When current sampling is required, the bypass switch 3 (triac) is closed, and the coil 1 automatically switches from the energy extraction loop 2 to the current sampling circuit 4, forming a closed loop through the sampling resistor R19 (in this embodiment, the impedance of R19 is 1 Ω). Since the impedance of the current sampling circuit is much smaller than that of the energy extraction loop, the energy extraction part is bypassed, and the current signal collected by the current sampling circuit is a complete signal. Since the bypass process is a natural bypass and the coil is not open at any time, the circuit is stable and reliable.

[0025] The working principle of the entire circuit is as follows: Under normal working conditions, CON_SCR1 is pulled low, and the bypass switch 3 is closed. The coil 1 loop forms a loop through D7, D6, C17, the load, and GND to store energy for the system. When current sampling is required, CON_SCR1 is pulled high, and the bidirectional AC optocoupler conducts. Since the impedance of R19 is 1 Ω, which is much smaller than the impedance of the energy extraction circuit, the coil loop forms a loop through the bidirectional AC optocoupler and R19 to GND. At this time, a voltage is induced on R19, and a differential signal is formed through the low-pass filter composed of R18, R21, C14, and C16 for system sampling.

[0026] The above are only the preferred embodiments of the present utility model, and are not intended to limit the present utility model in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the technical solution content of the present utility model still fall within the protection scope of the technical solution of the present utility model.

Claims

1. An energy-taking current-measuring circuit for monitoring the operating conditions of low-voltage distribution network conductors, characterized in that, It includes a coil, an energy extraction circuit, a bypass switch and a current sampling circuit. The coil is connected to the energy extraction circuit, and the coil is also connected to the current sampling circuit through the bypass switch. The impedance of the current sampling circuit is less than that of the energy extraction loop. By opening and closing the bypass switch, the operation of the energy extraction circuit and the current sampling circuit is switched.

2. The energy-taking current-measuring circuit for monitoring the operating conditions of low-voltage distribution network conductors according to claim 1, wherein The energy extraction circuit includes a bidirectional clamping diode D7, a rectifying diode D4, a unidirectional clamping diode D6, a rectifying diode D5 and an energy storage capacitor C17. Both ends of the coil are connected in parallel with both ends of the bidirectional clamping diode D7. After the unidirectional clamping diode D6, the rectifying diode D5 and the energy storage capacitor C17 are connected in parallel, they are connected in series with the rectifying diode D4, and then the whole is connected in parallel with both ends of the bidirectional clamping diode D7.

3. The energy-taking current-measuring circuit for monitoring the operating conditions of low-voltage distribution network conductors according to claim 2, wherein The first connection end of the coil is simultaneously connected to the first connection end of the bidirectional clamping diode D7, the positive electrode of the rectifying diode D4 and the bypass switch. The negative electrode of the rectifying diode D4 is simultaneously connected to the negative electrode of the unidirectional clamping diode D6, the negative electrode of the rectifying diode D5 and the first connection end of the energy storage capacitor C17. The second connection end of the bidirectional clamping diode D7, the positive electrode of the unidirectional clamping diode D6, the positive electrode of the rectifying diode D5 and the second connection end of the energy storage capacitor C17 are simultaneously connected to the second connection end of the coil and grounded.

4. The energy-taking current-measuring circuit for monitoring the operating conditions of low-voltage distribution network conductors according to claim 2, wherein The coil induces a current signal, which is rectified by the rectifying diode D4 and stored in the capacitor C17 to supply energy outward. The bidirectional clamping diode D7 and the unidirectional clamping diode D6 clamp the voltage to 5.5V.

5. The energy-taking current-measuring circuit for monitoring the operating conditions of low-voltage distribution network conductors according to claim 1, characterized in that, The bypass switch uses an optocoupler. The control signal pin of the bypass switch is connected to the control signal CON_SCR1. The two AC signal pins of the bypass switch are respectively connected to the coil and the current sampling circuit. When the control signal CON_SCR1 is pulled high, the optocoupler conducts, and the coil current forms a loop through the current sampling circuit, automatically bypassing the energy extraction circuit.

6. The energy-taking current-measuring circuit for monitoring the operating conditions of low-voltage distribution network conductors according to claim 5, wherein, The bypass switch uses an MOC3023 optocoupler. Its pin 1 is connected to the control signal CON_SCR1 through a current-limiting resistor R1. Pins 2 and 3 are simultaneously grounded. Pin 4 is connected to the coil, and pin 6 is connected to the current sampling circuit.

7. The energy-taking current-measuring circuit for monitoring the operating conditions of low-voltage distribution network conductors according to claim 1, characterized in that, The current sampling circuit includes a sampling resistor R19, a first filter resistor R18, a second filter resistor R21, a first filter capacitor C14, a second filter capacitor C15, and a third filter capacitor C16. A first connection end of the sampling resistor R19 is simultaneously connected to a bypass switch and a first connection end of the second filter resistor R21. A second connection end of the sampling resistor R19 is simultaneously connected to a first connection end of the first filter resistor R18 and grounded. A second connection end of the first filter resistor R18 is simultaneously connected to a first connection end of the first filter capacitor C14 and a first connection end of the second filter capacitor C15. A second connection end of the first filter capacitor C14 is connected to a first connection end of the third filter capacitor C16. A second connection end of the second filter resistor R21 is simultaneously connected to a second connection end of the second filter capacitor C15 and a second connection end of the third filter capacitor C16. The coil forms a loop through the sampling resistor R19 after being connected to the bypass switch. The first filter resistor R18, the second filter resistor R21, the first filter capacitor C14, and the third filter capacitor C16 form a low-pass filter, and the second filter capacitor C15 performs differential-mode filtering.

8. The energy-taking current-measuring circuit for monitoring the operating conditions of low-voltage distribution network conductors according to claim 7, characterized in that Both ends of the second filter capacitor C15 are connected to a metering chip for current calculation.

Images