CN213072095U - Nanocrystalline magnetic core current transformer overcurrent protection circuit - Google Patents
Nanocrystalline magnetic core current transformer overcurrent protection circuit Download PDFInfo
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Abstract
An over-current protection circuit of a nanocrystalline magnetic core current transformer relates to the technical field of over-current detection of the current transformer, and solves the problem of how to design an over-current protection circuit of a nanocrystalline magnetic core current transformer, which has a signal isolation function, a simple structure and low cost; the method comprises the following steps that a current transformer, an overcurrent comparison circuit and a processing circuit with a current protection point are adopted, the output end of the current transformer is connected with one input end of the overcurrent comparison circuit, and the output end of the processing circuit with the current protection point is connected with the other input end of the overcurrent comparison circuit; the current transformer is made of a nanocrystalline magnetic core; the adopted nanocrystalline magnetic core has extremely high magnetic permeability, high saturation magnetic induction intensity, low coercive force and low loss, input signals are isolated according to the electromagnetic induction principle, and the overcurrent protection circuit outputs overcurrent protection signals after comparing signals input by the current transformer and the processing circuit provided with the current protection point by adopting the overcurrent comparison circuit.
Description
Technical Field
The utility model relates to a current transformer overflows and detects technical field, is a nanocrystalline magnetic core current transformer overcurrent protection circuit particularly.
Background
The nanocrystalline magnetic core has extremely high magnetic permeability and wide frequency characteristic, and the nanocrystalline magnetic core still has high magnetic permeability up to the high frequency of 30 MHz. The method is very suitable for an EMC filter and a common-mode inductor to inhibit common-mode noise. Compared with the traditional soft magnetic material, such as a ferrite magnetic core, the nanocrystalline magnetic core has obvious advantages, high inductance, good filtering effect, small volume and less copper wire turns. The method is widely applied to the field of new energy resources, such as solar inverters, wind power generation and other occasions.
The nanocrystalline magnetic core current transformer is a current detection device specially designed for short circuit and occasions needing overcurrent protection; the main function is to convert the large current on the primary side into the small current on the secondary side, and then the small current on the secondary side passes through the overcurrent protection circuit, thereby achieving the purpose of measuring and protecting the main circuit.
The current detection ring, the Hall current sensor, the shunt and the like are commonly used in the market for collecting large current overcurrent. The common high-current sensor in the market is high in price, needs signal isolation and interference resistance, and the design cost of a matched acquisition circuit is high; the Hall current sensor has the limitation of high current and weak anti-interference capability; the shunt has the defect of non-isolation.
SUMMERY OF THE UTILITY MODEL
The utility model aims at designing a nanocrystalline magnetic core current transformer overcurrent protection circuit with signal isolation function, simple structure, low price to the problem among the prior art.
The utility model discloses a solve above-mentioned technical problem through following technical scheme.
An overcurrent protection circuit of a nanocrystalline magnetic core current transformer comprises a current transformer (T2), an overcurrent comparison circuit and a processing circuit for setting a current protection point, wherein the output end of the current transformer (T2) is connected with one input end of the overcurrent comparison circuit, and the output end of the processing circuit for setting the current protection point is connected with the other input end of the overcurrent comparison circuit; the current transformer (T2) is made of a nanocrystalline magnetic core; the overcurrent comparison circuit compares signals input by the current transformer (T2) and the processing circuit for setting the current protection point and then outputs an overcurrent protection signal.
The adopted nanocrystalline magnetic core has extremely high magnetic permeability, high saturation magnetic induction intensity, low coercive force and low loss, an input signal is isolated according to the electromagnetic induction principle, and an overcurrent protection circuit outputs an overcurrent protection signal after comparing a signal input by a current transformer (T2) and a processing circuit provided with a current protection point by adopting an overcurrent comparison circuit.
As a further improvement of the technical solution of the present invention, the over-current comparison circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a capacitor C2, a capacitor C3, and a comparator (U1); the output end of the current transformer (T2) is connected in parallel with the two ends of the resistor R4; one end of the resistor R4 is grounded, the other end is connected with one end of the resistor R2, and the other end of the resistor R2 is connected with the No. 2 terminal of the comparator (U1); one end of the resistor R3 is connected with the output end of the processing circuit for setting the current protection point, and the other end is connected with the 3# terminal of the comparator (U1); the 8# terminal of the comparator (U1) is connected with a +24V power supply, and the 1# terminal of the comparator (U1) is grounded; one end of the capacitor C1 is connected with the 2# terminal of the comparator (U1), the other end of the capacitor C3578 is connected with one end of the capacitor C2, the other end of the capacitor C2 is connected with the 8# terminal of the comparator (U1), and the common connection point of the capacitor C1 and the capacitor C2 is grounded; one end of the capacitor C3 is connected to the 3# terminal of the comparator (U1), and the other end is connected to the 1# terminal of the comparator (U1); the 4# terminal of the comparator (U1) is directly connected with the 1# terminal of the comparator (U1), and the 5# terminal and the 6# terminal of the comparator (U1) are suspended; one end of the resistor R1 is connected with a +5V power supply, the other end is connected with the 7# terminal of the comparator (U1), and the common connection point of the resistor R1 and the comparator (U1) is used as an output overcurrent comparison circuit.
As the further improvement of the technical proposal of the utility model, the comparator (U1) is LM 211.
As a further improvement of the technical solution of the present invention, the processing circuit for setting the current protection point includes a resistor R5, a resistor R6, a resistor R7, a resistor R8, a capacitor C4, a capacitor C5, and an amplifier (U2); one end of the resistor R5 is used as the input end of the PWM signal, and the other end is connected with the No. 5 terminal of the amplifier (U2); the 6# terminal and the 7# terminal of the amplifier (U2) are directly connected; one end of the capacitor C5 is connected to the No. 5 terminal of the amplifier (U2), and the other end is grounded; one end of the resistor R6 is connected to the 7# terminal of the amplifier (U2), and the other end is connected to the 3# terminal of the amplifier (U2); the 8# terminal of the amplifier (U2) is connected with a +24V power supply; one end of the capacitor C4 is connected with the 8# terminal of the amplifier (U2), and the other end is grounded; one end of the resistor R7 is connected with the 2# terminal of the amplifier (U2), and the other end is connected with the 4# terminal of the amplifier (U2); the 4# terminal of the amplifier (U2) is grounded; the resistor R8 is connected between the 2# terminal of the amplifier (U2) and the 1# terminal of the amplifier (U2); the resistor R6, the resistor R7 and the resistor R8 form a proportional amplification coefficient, and the capacitor C4 is a power supply filter capacitor of the amplifier (U2); the 1# terminal of the amplifier (U2) is used as the output end of the processing circuit for setting the current protection point and is connected with the resistor R3 of the over-current comparison circuit.
As a further improvement of the technical scheme of the utility model, the type of amplifier (U2) be the dual operational amplifier of LM258 AD.
As the further improvement of the technical proposal of the utility model, the turn ratio of the primary side and the secondary side of the current transformer (T2) is 1: 150.
as the further improvement of the technical proposal of the utility model, the outer diameter of the nanocrystalline magnetic core is 150mm, the inner diameter is 56mm, and the height is 23 mm.
The utility model has the advantages that:
(1) the adopted nanocrystalline magnetic core has extremely high magnetic permeability, high saturation magnetic induction intensity, low coercive force and low loss, an input signal is isolated according to the electromagnetic induction principle, and an overcurrent protection circuit outputs an overcurrent protection signal after comparing a signal input by a current transformer (T2) and a processing circuit provided with a current protection point by adopting an overcurrent comparison circuit.
(2) The test current of the nanocrystalline magnetic core wound current sensor is not less than 9000A, the current is collected through a resistor R4, and the circuit is simple and easy to realize.
Drawings
Fig. 1 is a main circuit diagram of an overcurrent protection circuit of a nanocrystalline magnetic core current transformer according to an embodiment of the present invention;
fig. 2 is the utility model discloses a nanocrystalline magnetic core current transformer's of nanocrystalline magnetic core current transformer overcurrent protection circuit structure chart.
Detailed Description
In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the embodiments of the present invention are combined with the following description to clearly and completely describe the technical solution in the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
The technical solution of the present invention is further described below with reference to the drawings and specific embodiments of the specification:
example one
As shown in fig. 1, an overcurrent protection circuit for a nanocrystalline magnetic core current transformer includes a current transformer T2, an overcurrent comparison circuit, and a processing circuit for setting a current protection point; the output end of the current transformer T2 is connected with one input end of the over-current comparison circuit, and the output end of the processing circuit with the current protection point is connected with the other input end of the over-current comparison circuit; the overcurrent comparison circuit compares signals input by the current transformer T2 and the processing circuit for setting the current protection point and then outputs an overcurrent protection signal.
The over-current comparison circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a capacitor C2, a capacitor C3 and a comparator U1; the comparator U1 is LM 211; the output end of the current transformer T2 is connected in parallel with the two ends of the resistor R4; one end of the resistor R4 is grounded, the other end is connected with one end of the resistor R2, and the other end of the resistor R2 is connected with the No. 2 terminal of the comparator U1; one end of the resistor R3 is connected with the output end of the processing circuit for setting the current protection point, and the other end is connected with the 3# terminal of the comparator U1; the 8# terminal of the comparator U1 is connected with a +24V power supply, and the 1# terminal of the comparator U1 is grounded; one end of the capacitor C1 is connected to the 2# terminal of the comparator U1, the other end of the capacitor C1 is connected to one end of the capacitor C2, the other end of the capacitor C2 is connected to the 8# terminal of the comparator U1, and the common connection point of the capacitor C1 and the capacitor C2 is grounded; one end of the capacitor C3 is connected to the # 3 terminal of the comparator U1, and the other end is connected to the # 1 terminal of the comparator U1; the 4# terminal of the comparator U1 is directly connected with the 1# terminal of the comparator U1, and the 5# terminal and the 6# terminal of the comparator U1 are suspended; one end of the resistor R1 is connected with a +5V power supply, the other end is connected with the 7# terminal of the comparator U1, and the common connection point of the resistor R1 and the comparator U1 is used as an output overcurrent comparison circuit.
The processing circuit for setting the current protection point comprises a resistor R5, a resistor R6, a resistor R7, a resistor R8, a capacitor C4, a capacitor C5 and an amplifier U2; the amplifier U2 is a double operational amplifier with the model number LM258 AD; one end of the resistor R5 is used as an input end of the PWM signal, and the other end is connected with the No. 5 terminal of the amplifier U2; the 6# terminal and the 7# terminal of the amplifier U2 are directly connected; one end of the capacitor C5 is connected to the No. 5 terminal of the amplifier U2, and the other end is grounded; one end of the resistor R6 is connected to the 7# terminal of the amplifier U2, and the other end is connected to the 3# terminal of the amplifier U2; the 8# terminal of the amplifier U2 is connected with a +24V power supply; one end of the capacitor C4 is connected with the No. 8 terminal of the amplifier U2, and the other end is grounded; one end of the resistor R7 is connected with the 2# terminal of the amplifier U2, and the other end is connected with the 4# terminal of the amplifier U2; the # 4 terminal of the amplifier U2 is grounded; the resistor R8 is connected between the 2# terminal of the amplifier U2 and the 1# terminal of the amplifier U2; the resistor R6, the resistor R7 and the resistor R8 form a proportional amplification coefficient, and the capacitor C4 is a filter capacitor for supplying power to the amplifier U2; the 1# terminal of the amplifier U2 is used as the output end of the processing circuit for setting the current protection point and is connected with the resistor R3 of the over-current comparison circuit.
The operating principle of the over-current protection circuit of the nanocrystalline magnetic core current transformer is as follows:
(1) a resistor R4 of the overcurrent comparison circuit collects the output current of a current transformer T2, and the output current is filtered by a resistor R2 and a capacitor C1 and then is input into a comparator U1;
(2) a current protection point processing circuit is arranged, an input PWM signal is filtered by a resistor R5 and a capacitor C1 and then input to an amplifier U2 for voltage following and amplification, and the filtered PWM signal is input to a comparator U1 after being filtered by a resistor R3 and a capacitor C3;
(3) the two input signals pass through a comparator U1 to output comparison results.
As shown in fig. 2, the current transformer T2 is made of a nanocrystalline magnetic core, the nanocrystalline magnetic core has an outer diameter of 150mm, an inner diameter of 56mm, and a height of 23mm, has the characteristics of extremely high magnetic permeability, high saturation magnetic induction, low coercive force, and low loss, and is suitable for application of the current transformer; turn ratio of primary side and secondary side of current transformer T2 is 1: 150, and ensuring that the test current is more than or equal to 9000A.
The current transformer is the core of the whole main circuit, the nanocrystalline magnetic core is the mechanical skeleton of the current transformer, and the magnetic core and the coil winding wound on the magnetic core form a complete electromagnetic induction system. When a large current passes through the center of the magnetic core, a magnetic field is generated, and through electromagnetic and magnetic electricity generation, a current is induced on a coil on the magnetic core, and the current is converted into a direct current through the turn ratio of 1: 150, the coil current obtained is 1/150 small current with large current, and the duration of the large current is short when the coil is applied as an overcurrent protection circuit, so that the phenomenon of magnetic saturation does not exist. The secondary side induces current signals, so that the anti-interference capability is strong. The current signal is sent to the overcurrent protection circuit, the current signal is converted into voltage through the sampling resistor, the voltage value corresponding to the required overcurrent point can be set through formula conversion, the set voltage value is compared with the voltage signal converted through the sampling resistor after being filtered and amplified, and the comparison result is used as the basis for judging whether the current point at the set point is exceeded.
The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention in its corresponding aspects.
Claims (7)
1. The over-current protection circuit of the current transformer with the nanocrystalline magnetic core is characterized by comprising a current transformer (T2), an over-current comparison circuit and a processing circuit for setting a current protection point, wherein the output end of the current transformer (T2) is connected with one input end of the over-current comparison circuit, and the output end of the processing circuit for setting the current protection point is connected with the other input end of the over-current comparison circuit; the current transformer (T2) is made of a nanocrystalline magnetic core; the overcurrent comparison circuit compares signals input by the current transformer (T2) and the processing circuit for setting the current protection point and then outputs an overcurrent protection signal.
2. The over-current protection circuit of the nanocrystalline core current transformer of claim 1, wherein the over-current comparison circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a capacitor C2, a capacitor C3, a comparator (U1); the output end of the current transformer (T2) is connected in parallel with the two ends of the resistor R4; one end of the resistor R4 is grounded, the other end is connected with one end of the resistor R2, and the other end of the resistor R2 is connected with the No. 2 terminal of the comparator (U1); one end of the resistor R3 is connected with the output end of the processing circuit for setting the current protection point, and the other end is connected with the 3# terminal of the comparator (U1); the 8# terminal of the comparator (U1) is connected with a +24V power supply, and the 1# terminal of the comparator (U1) is grounded; one end of the capacitor C1 is connected with the 2# terminal of the comparator (U1), the other end of the capacitor C3578 is connected with one end of the capacitor C2, the other end of the capacitor C2 is connected with the 8# terminal of the comparator (U1), and the common connection point of the capacitor C1 and the capacitor C2 is grounded; one end of the capacitor C3 is connected to the 3# terminal of the comparator (U1), and the other end is connected to the 1# terminal of the comparator (U1); the 4# terminal of the comparator (U1) is directly connected with the 1# terminal of the comparator (U1), and the 5# terminal and the 6# terminal of the comparator (U1) are suspended; one end of the resistor R1 is connected with a +5V power supply, the other end is connected with the 7# terminal of the comparator (U1), and the common connection point of the resistor R1 and the comparator (U1) is used as an output overcurrent comparison circuit.
3. The overcurrent protection circuit of the current transformer with the nanocrystalline core according to claim 2, wherein the comparator (U1) is LM 211.
4. The over-current protection circuit of the nanocrystalline magnetic core current transformer of claim 2, wherein the processing circuit for setting the current protection point comprises a resistor R5, a resistor R6, a resistor R7, a resistor R8, a capacitor C4, a capacitor C5 and an amplifier (U2); one end of the resistor R5 is used as the input end of the PWM signal, and the other end is connected with the No. 5 terminal of the amplifier (U2); the 6# terminal and the 7# terminal of the amplifier (U2) are directly connected; one end of the capacitor C5 is connected to the No. 5 terminal of the amplifier (U2), and the other end is grounded; one end of the resistor R6 is connected to the 7# terminal of the amplifier (U2), and the other end is connected to the 3# terminal of the amplifier (U2); the 8# terminal of the amplifier (U2) is connected with a +24V power supply; one end of the capacitor C4 is connected with the 8# terminal of the amplifier (U2), and the other end is grounded; one end of the resistor R7 is connected with the 2# terminal of the amplifier (U2), and the other end is connected with the 4# terminal of the amplifier (U2); the 4# terminal of the amplifier (U2) is grounded; the resistor R8 is connected between the 2# terminal of the amplifier (U2) and the 1# terminal of the amplifier (U2); the resistor R6, the resistor R7 and the resistor R8 form a proportional amplification coefficient, and the capacitor C4 is a power supply filter capacitor of the amplifier (U2); the 1# terminal of the amplifier (U2) is used as the output end of the processing circuit for setting the current protection point and is connected with the resistor R3 of the over-current comparison circuit.
5. The overcurrent protection circuit of the current transformer with nanocrystalline magnetic core according to claim 4, wherein the amplifier (U2) is a dual operational amplifier of LM258AD type.
6. The over-current protection circuit of a nanocrystalline magnetic core current transformer according to claim 1, wherein the turn ratio of the primary side to the secondary side of the current transformer (T2) is 1: 150.
7. the overcurrent protection circuit of the current transformer with the nanocrystalline magnetic core according to claim 1, wherein the nanocrystalline magnetic core has an outer diameter of 150mm, an inner diameter of 56mm, and a height of 23 mm.
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| CN202022132884.XU CN213072095U (en) | 2020-09-25 | 2020-09-25 | Nanocrystalline magnetic core current transformer overcurrent protection circuit |
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| CN202022132884.XU CN213072095U (en) | 2020-09-25 | 2020-09-25 | Nanocrystalline magnetic core current transformer overcurrent protection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113671409A (en) * | 2021-08-12 | 2021-11-19 | 厦门京福通信有限公司 | Current acquisition protection circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113671409A (en) * | 2021-08-12 | 2021-11-19 | 厦门京福通信有限公司 | Current acquisition protection circuit |
| CN113671409B (en) * | 2021-08-12 | 2024-04-12 | 厦门京福通信有限公司 | Current acquisition protection circuit |
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Address after: 230088 Building 2, Hupu Industrial Park, No. 4715, Wangjiang West Road, hi tech Zone, Hefei City, Anhui Province Patentee after: Cowell Technology Co.,Ltd. Address before: 230088 Building 2, Hupu Industrial Park, No. 4715, Wangjiang West Road, hi tech Zone, Hefei City, Anhui Province Patentee before: Hefei Kewei Power System Co.,Ltd. |