Low-current CT (Current Transformer) electricity taking circuit for overhead line

Abstract

The utility model discloses a low-current CT (Current Transformer) electricity taking circuit for an overhead line, which belongs to the field of overhead power supply lines, and when the line is in a low-current state, a CT electricity taking device can stably output a preset value to ensure that a rear-end circuit can obtain normal working voltage. The circuit mainly comprises an oscillation circuit and a discharge protection circuit, the discharge protection circuit comprises a silicon controlled rectifier D5 and a silicon controlled rectifier D6, the silicon controlled rectifier D5 is connected in parallel with two ends of the oscillation circuit, a G pole of the silicon controlled rectifier D5 is connected with a T1 pole of the silicon controlled rectifier D6, a G pole of the silicon controlled rectifier D6 is respectively connected with a resistor R17 and a resistor R18, the resistor R18 is connected with an anode of a voltage-regulator tube D7, and a cathode of the voltage-regulator tube D7 is connected with a cathode of a voltage-regulator tube D8. The anode of the resistor R17 and the anode of the voltage-regulator tube D8 are connected to the two ends of the silicon bridge rectifier circuit respectively, and the two ends of the silicon bridge rectifier circuit are connected with filter circuits in parallel respectively. The utility model is mainly used for small current CT voltage stabilization electricity taking.

Description

Technical Field

[0001] The utility model relates to the field of overhead power supply lines, and more particularly to a small current CT power taking circuit for overhead lines. Background Art

[0002] A current induction power supply, also known as a CT power taking power supply or a current transformer power taking power supply, takes power from the magnetic field induced by the load current of a wire. The isolation transformation of the power supply mainly relies on the principle of electromagnetic induction, and can perform both voltage transformation and current transformation, such as the integrated CT induction power taking circuit and device with the publication number CN111969574A. The current transformer of the overhead circuit has a small volume and light weight, but is strongly affected by current fluctuations. When the line is in a small current state, the voltage taken by the CT is very low and cannot provide an effective power supply for the energy storage device, and the energy storage device cannot effectively supplement electric energy, resulting in the abnormal operation of the equipment. Summary of the Utility Model

[0003] The purpose of the utility model is to provide a small current CT power taking circuit for overhead lines, which protects the stability and safety of the circuit through a discharge circuit; realizes the purpose of boosting and bucking through a voltage stabilizing circuit; when the line is in a small current state, enables the CT power taking device to stably output a preset value, ensuring that the subsequent circuit can obtain a normal working voltage.

[0004] The utility model is realized by the following technical solutions:

[0005] A small current CT power taking circuit for overhead lines includes an oscillation circuit and a discharge protection circuit. The discharge protection circuit includes thyristors D5 and D6. The two ends of the oscillation circuit are connected in parallel with thyristor D5. The G pole of thyristor D5 is connected to the T1 pole of thyristor D6. The G pole of thyristor D6 is respectively connected to resistor R17 and resistor R18. Resistor R18 is connected to the anode of voltage stabilizing diode D7. The cathode of voltage stabilizing diode D7 is connected to the cathode of voltage stabilizing diode D8. Resistor R17 and the anode of voltage stabilizing diode D8 are respectively connected to both ends of a silicon bridge rectifier circuit, and filter circuits are respectively connected in parallel at both ends of the silicon bridge rectifier circuit; the silicon bridge rectifier circuit includes diodes D9, D10, D11 and D12.

[0006] Further, the oscillation circuit includes resistor R14 and capacitor C18. Resistor R14 and capacitor C18 are connected in series and then connected in parallel to the CT input end. The CT input end is also connected in parallel with compensation capacitor C17.

[0007] Further, the G pole of thyristor D5 is also connected with protection resistor R15, and the T2 pole of thyristor D6 is also connected with protection resistor R16.

[0008] Further, the filtering circuit includes a parallel connection of a filtering capacitor C20 and a filtering capacitor C5.

[0009] Further, a voltage stabilizing circuit is also included. The voltage stabilizing circuit includes a power supply chip U2. The HO pin of the power supply chip U2 is connected to the G pole of the field effect transistor Q1. The S pole of the field effect transistor Q1 is respectively connected to the inductor L1 and the cathode of the voltage stabilizing diode D1. The anode of the voltage stabilizing diode D1 is connected to the CS pin of the power supply chip U2. The cathode of the voltage stabilizing diode D1 is also respectively connected to the HB pin and the HS pin of the power supply chip U2. The LO pin of the power supply chip U2 is connected to the G pole of the field effect transistor Q2. The D pole of the field effect transistor Q2 is respectively connected to the inductor L1 and the voltage stabilizing diode D2.

[0010] Further, the power supply chip U2 is a BUCK - BOOST chip.

[0011] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0012] 1. Through the discharging circuit, the stability and safety of the circuit are protected; through the voltage stabilizing circuit, the purpose of boosting and bucking is achieved.

[0013] 2. When the line is in a small - current state, the CT power - taking device can stably output a preset value, ensuring that the subsequent circuit can obtain a normal working voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is the discharging and rectifying circuit diagram of the present utility model;

[0015] Figure 2 is the voltage stabilizing circuit diagram of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The present utility model will be further described below with reference to the drawings.

[0017] Embodiment 1

[0018] As Figure 1 shown, an overhead line small - current CT power - taking circuit includes an oscillation circuit and a discharging protection circuit. The discharging protection circuit includes a thyristor D5 and a thyristor D6. The two ends of the oscillation circuit are connected in parallel with the thyristor D5. The G pole of the thyristor D5 is connected to the T1 pole of the thyristor D6. The G pole of the thyristor D6 is respectively connected to a resistor R17 and a resistor R18. The resistor R18 is connected to the anode of a voltage - stabilizing diode D7. The cathode of the voltage - stabilizing diode D7 is connected to the cathode of a voltage - stabilizing diode D8. The resistor R17 and the anode of the voltage - stabilizing diode D8 are respectively connected to both ends of a silicon - bridge rectifying circuit. Filtering circuits are respectively connected in parallel to both ends of the silicon - bridge rectifying circuit; the silicon - bridge rectifying circuit includes a diode D9, a diode D10, a diode D11, and a diode D12, which rectify alternating current and output direct current.

[0019] When the current in the power supply line is too large and the AC voltage value sensed by the CT is not greater than 70V, the voltage regulator diodes D7 or D8 are not broken down and do not conduct, the G pole of the thyristor D6 is at a high level, causing the thyristor D6 to conduct, resulting in the G pole of the thyristor D5 being at a low level, and the thyristor D5 does not conduct. The AC voltage sensed by the CT does not pass through the discharge path.

[0020] When the current in the power supply line is too large and the AC voltage value sensed by the CT is greater than 70V, the voltage regulator diodes D7 or D8 are broken down and conduct, the G pole of the thyristor D6 is at a low level, the thyristor D6 does not conduct, the G pole of the thyristor D5 is at a high level, the thyristor D5 conducts, and current discharge is carried out to ensure that the voltage at the input end of the rectifier circuit does not exceed 70V, protecting the subsequent circuit.

[0021] Embodiment 2

[0022] As Figure 2 shown, a small-current CT power-taking circuit for an overhead line, the oscillation circuit includes a resistor R14 and a capacitor C18. The resistor R14 and the capacitor C18 are connected in series and then connected in parallel to the CT input end. A compensation capacitor C17 is also connected in parallel to the CT input end; the G pole of the thyristor D5 is also connected to a protection resistor R15, and the T2 pole of the thyristor D6 is also connected to a protection resistor R16; the filtering circuit includes a parallel filtering capacitor C20 and a filtering capacitor C5; a voltage regulation circuit is also included. The voltage regulation circuit includes a power supply chip U2. The HO pin of the power supply chip U2 is connected to the G pole of the field effect transistor Q1. The S pole of the field effect transistor Q1 is respectively connected to an inductor L1 and the cathode of a voltage regulation diode D1. The anode of the voltage regulation diode D1 is connected to the CS pin of the power supply chip U2. The cathode of the voltage regulation diode D1 is also respectively connected to the HB pin and the HS pin of the power supply chip U2. The LO pin of the power supply chip U2 is connected to the G pole of the field effect transistor Q2. The D pole of the field effect transistor Q2 is respectively connected to the inductor L1 and the voltage regulation diode D2; the power supply chip U2 is a BUCK-BOOST chip. The voltage regulation circuit is composed of the power supply chip U2 and its accessory circuits to provide a stable voltage for the subsequent energy storage device to ensure its normal operation. The rest is the same as that in Embodiment 1. The rest of the voltage regulation circuit is the prior art and will not be elaborated.

[0023] When VIN is greater than VOUT, the duty cycle of the square wave output by the HO pin of the power supply chip U2 decreases, resulting in the conduction time of the field effect transistor Q1 being less than the turn-off time, and filtering and output through the inductor L1 to achieve the purpose of step-down. When VIN decreases relative to VOUT, the duty cycle of the square wave output by the HO pin of the power supply chip U2 will increase to maintain regulation. The LO pin of the power supply chip U2 outputs a square wave and starts to operate with a very small duty cycle; when VIN drops below VOUT, the step-down and step-up switches work together with the voltage regulation diode D1 with the same duty cycle, and filter and output through the inductor L1 to achieve the purpose of step-up.

Claims

1. An overhead line low current CT power supply circuit, comprising an oscillating circuit and a discharge protection circuit, wherein the discharge protection circuit comprises a thyristor D5 and a thyristor D6, characterized in that: The two ends of the oscillation circuit are connected in parallel with a thyristor D5, the G pole of the thyristor D5 is connected to the T1 pole of the thyristor D6, the G pole of the thyristor D6 is connected to the resistor R17 and the resistor R18 respectively, the resistor R18 is connected to the anode of the zener tube D7, the cathode of the zener tube D7 is connected to the cathode of the zener tube D8, the resistor R17 and the anode of the zener tube D8 are respectively connected to the two ends of the silicon bridge rectifier circuit, and the two ends of the silicon bridge rectifier circuit are respectively connected in parallel with a filter circuit.

2. The overhead line low current CT power supply circuit according to claim 1, characterized in that: The oscillation circuit comprises a resistor R14 and a capacitor C18, which are connected in series and then in parallel to a CT input terminal, and a compensation capacitor C17 is also connected in parallel to the CT input terminal.

3. The overhead line low current CT power supply circuit according to claim 1, characterized in that: The G pole of the thyristor D5 is also connected to a protective resistor R15, and the T2 pole of the thyristor D6 is also connected to a protective resistor R16.

4. The overhead line low current CT power supply circuit according to claim 1, characterized in that: The filter circuit includes a filter capacitor C20 and a filter capacitor C5 connected in parallel.

5. The overhead line low current CT power supply circuit according to claim 1, characterized in that: It also includes a voltage stabilizing circuit, which includes a power chip U2, the HO pin of the power chip U2 is connected to the G pole of the field effect transistor Q1, the S pole of the field effect transistor Q1 is respectively connected to the cathode of the inductor L1 and the voltage stabilizing diode D1, the anode of the voltage stabilizing diode D1 is connected to the CS pin of the power chip U2, the cathode of the voltage stabilizing diode D1 is also respectively connected to the HB pin and HS pin of the power chip U2, the LO pin of the power chip U2 is connected to the G pole of the field effect transistor Q2, and the D pole of the field effect transistor Q2 is respectively connected to the inductor L1 and the voltage stabilizing diode D2.

6. The overhead line low current CT power supply circuit according to claim 5, characterized in that: The power chip U2 is a BUCK-BOOST chip.

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