A protection circuit based on reed switch on / off state

Abstract

This invention provides a protection circuit based on reed switch switching. The protection circuit protects a power switch circuit, which includes an input circuit, an output circuit, a high-frequency transformer, and a reed switch. The protection circuit includes a magnetic core coil, a current-limiting resistor R1, and a mutual inductance coil. The first coil of the mutual inductance coil is connected in series in the input circuit. The second coil of the mutual inductance coil, the secondary induction coil of the high-frequency transformer, the magnetic core coil, and the current-limiting resistor R1 form a loop. Under normal conditions, the reed switch K1 remains normally closed. When an abnormality occurs in the power switch circuit, the mutual inductance currents on the primary and secondary sides of the high-frequency transformer are superimposed, reducing the magnetic field strength of the magnetic core coil, and causing the reed switch K1 to open. By introducing a magnetic core, even a small change in the current in the transformer's induction coil can significantly alter the magnetic properties of the magnetic core, thereby increasing the sensitivity of the protection circuit and accelerating its protection speed.

Description

Technical Field

[0001] This utility model relates to the field of electronics and electrical engineering, specifically a protection circuit technology based on reed switch on / off switching. Background Technology

[0002] A switching power supply is an electronic device that provides power to other electrical devices. The high-frequency transformer is the core component of a switching power supply, through which the circuit converts energy. Its principle is based on using a changing electric field to induce a magnetic field. Electrical energy from the circuit is coupled to the secondary coil circuit through this magnetic field, and then rectified and filtered before being output to power other devices. In this circuit, the input and output protection circuits typically use ordinary fuses or resettable fuses. When external conditions change, such as overload, short circuit, or voltage fluctuations exceeding the allowable range, these fuses may blow to protect critical circuits. Once a fuse has fulfilled its protective function, it will blow, causing the circuit to disconnect. When external conditions return to normal, the fuse's state is irreversible; only replacement can restore the circuit to normal. Summary of the Invention

[0003] This utility model addresses the problems existing in the prior art by providing a protection circuit based on the on / off switching of a reed switch. This protection circuit can simply disconnect the circuit to provide protection when the electronic circuit is overloaded or short-circuited. When the external circuit returns to normal, the reed switch will automatically close, realizing the circuit self-recovery technology.

[0004] To achieve the above-mentioned technical objectives, this utility model provides a protection circuit based on reed switch switching for protecting a power switch circuit. The power switch circuit includes an input circuit, an output circuit, a high-frequency transformer, and a reed switch. The primary induction coil of the high-frequency transformer is connected in series in the input circuit, and the secondary induction coil of the high-frequency transformer and the reed switch are connected in series in the output circuit. The protection circuit is characterized in that it controls the turn-off of the reed switch K1; the protection circuit includes a magnetic core coil, a current-limiting resistor R1, and a mutual inductance coil. The first coil of the mutual inductance coil is connected in series in the input circuit, and the second coil of the mutual inductance coil, the secondary induction coil of the high-frequency transformer, the magnetic core coil, and the current-limiting resistor R1 form a loop.

[0005] Under normal conditions, the reed switch K1 remains closed. When the power switch circuit malfunctions, the mutual inductance currents on the primary and secondary sides of the high-frequency transformer are superimposed, the magnetic field strength of the magnetic core coil decreases, and the reed switch K1 is opened.

[0006] The preferred technical solution of this utility model is as follows: the primary winding of the high-frequency transformer includes an upper winding group and a lower winding group, and the first winding of the mutual inductance coil is connected in series in the input main circuit of the upper winding group of the primary winding; the secondary winding of the high-frequency transformer also includes an upper winding group and a lower winding group, and the upper winding of the secondary winding, the reed switch K1 and the load form an output circuit; the second winding of the mutual inductance coil, the lower winding of the secondary winding, the current limiting resistor and the magnetic core coil form a loop.

[0007] A further technical solution of this utility model: the lower winding of the secondary side induction coil of the high-frequency transformer is used to sense the magnetic changes in the high-frequency transformer, and the second coil of the mutual inductance coil is used to sense the current changes on the primary side of the high-frequency transformer. The current changes induced by the secondary side induction coil of the high-frequency transformer and the current changes induced by the second coil of the mutual inductance coil are superimposed to form a changing constant current source, which is connected in series with the current limiting resistor R1 and the magnetic core coil to form a circuit.

[0008] A further technical solution of this utility model: the magnetic core coil is made of a high magnetic permeability material, and the magnetic core coil is located below the lower winding of the induction coil on the secondary side of the high-frequency transformer.

[0009] The preferred technical solution of this utility model is that the reed switch passes through the magnetic core coil and is embedded inside the magnetic core coil.

[0010] A further technical solution of this utility model: the second coil of the mutual inductance coil is opposite to the lower winding of the induction coil on the secondary side of the high-frequency transformer, and is connected in series in the circuit.

[0011] A further technical solution of this utility model: Based on the closed current data of the magnetic core coil, and through the selection of the current-limiting resistor R1, during normal circuit operation, the current induced by the second coil of the mutual inductance coil and the induction coil on the secondary side of the high-frequency transformer is superimposed. The superimposed current is less than the closed current of the magnetic core coil. At this time, the magnetic core coil does not operate, the reed switch K1 remains normally closed, and the circuit operates normally. When an abnormality occurs in the circuit, whether it is an abnormality in the primary coil circuit or the output circuit, anything that causes a change in the main transformer magnetic field, thereby causing a change in the induced electromotive force, will cause a change in the superimposed equivalent constant current source. When the output current of the constant current source is greater than the closed current data of the magnetic core coil, the magnetic core coil starts to work, causing the reed switch K1 to open, and the circuit is protected.

[0012] The working principle of this utility model is as follows: The circuit senses the current change in the high-frequency transformer through the main transformer induction coil of the high-frequency transformer. The current is superimposed with the induced current of the primary side mutual inductance coil and passes through the magnetic core to form a circuit through the current limiting resistor. Since the different induced currents affect the magnetic field strength of the magnetic core, the reed switch is controlled to open, thereby achieving the protection function. When the reed switch is subjected to external magnetic force, the state changes from normally closed to normally open. When the magnetic force disappears, the state returns to normal, changing from normally open to normally closed, thus realizing circuit protection.

[0013] The mutual inductance coil of this invention is divided into two parts. One part is connected in series with the primary-side induction coil of the high-frequency transformer in the input circuit to improve the circuit's response time. When the input circuit is connected to an AC220 power supply, the risk factor is higher compared to the coupled secondary circuit output circuit. When a problem occurs in the input circuit, the current rises, and the current in the primary-side mutual inductance coil rises accordingly. The constant current source formed in response rises accordingly. Compared to the part connected in series with the secondary-side induction coil of the high-frequency transformer, the primary-side mutual inductance coil connected in series with the input circuit responds faster, and the protection circuit responds faster.

[0014] The beneficial effects of this utility model are:

[0015] (1) This utility model utilizes the principle of reed switch being attracted and conducting under the action of external magnetic force. It is applied to the power output circuit. The primary side mutual inductance and the secondary side inductance are connected in series. When there is a fault in the power output or input, the primary side and the secondary side mutual inductance current are superimposed, which reduces the magnetic field strength of the magnetic core, thereby disconnecting the reed switch and playing a protective role.

[0016] (2) This utility model is used to protect the equipment circuit. When the equipment circuit is overloaded or short-circuited, it can disconnect it to play a protective role. When the external circuit returns to normal, the reed switch will automatically return to the closed state to realize the circuit self-recovery technology, thereby realizing the maintenance-free equipment circuit.

[0017] (3) By introducing a magnetic core, the present invention can make the magnetic properties of the magnetic core change significantly even with slight changes in the current in the main transformer induction coil, thereby increasing the sensitivity of the protection circuit and speeding up the protection of the circuit. Attached Figure Description

[0018] Figure 1 This is the circuit schematic diagram of this utility model;

[0019] Figure 2 This is a diagram showing the positional relationship between the reed switch and the magnetic core coil of this utility model.

[0020] In the diagram: 1—electromagnetic coil, 2—reed switch, 3—secondary induction coil of high-frequency transformer. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments. Figures 1 to 2 All accompanying drawings are simplified versions of embodiments and are intended solely for the purpose of clearly and concisely illustrating the embodiments of this utility model. The technical solutions shown in the drawings below are specific solutions of embodiments of this utility model and are not intended to limit the scope of the claimed utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

[0022] An embodiment provides a protection circuit based on reed switch switching for protecting a power switch circuit. The power switch circuit includes an input circuit, an output circuit, a high-frequency transformer, and a reed switch. The primary induction coil of the high-frequency transformer is connected in series in the input circuit, and the secondary induction coil of the high-frequency transformer and the reed switch are connected in series in the output circuit. The protection circuit is used to control the turn-off of the reed switch K1. The protection circuit includes a magnetic core coil, a current-limiting resistor R1, and a mutual inductance coil. The first coil of the mutual inductance coil is connected in series in the input circuit, and the second coil of the mutual inductance coil, the secondary induction coil of the high-frequency transformer, the magnetic core coil, and the current-limiting resistor R1 form a loop.

[0023] Under normal conditions, the reed switch K1 remains closed. When the power switch circuit malfunctions, the mutual inductance currents on the primary and secondary sides of the high-frequency transformer are superimposed, the magnetic field strength of the magnetic core coil decreases, and the reed switch K1 is opened.

[0024] The primary-side induction coil of the high-frequency transformer includes an upper winding and a lower winding. The first coil of the mutual inductance coil is connected in series in the input main circuit of the upper winding of the primary-side induction coil. The secondary-side induction coil of the high-frequency transformer also includes an upper winding and a lower winding. The upper winding of the secondary-side induction coil, the reed switch K1, and the load form the output circuit. The second coil of the mutual inductance coil, the lower winding of the secondary-side induction coil, the current-limiting resistor, and the magnetic core coil form a loop. The lower winding of the secondary-side induction coil of the high-frequency transformer is used to sense changes in the magnetic field of the high-frequency transformer. The second coil of the mutual inductance coil is used to sense changes in the current on the primary side of the high-frequency transformer. The current changes induced by the secondary-side induction coil of the high-frequency transformer and the current changes induced by the second coil of the mutual inductance coil are superimposed to form a changing constant current source, which is connected in series with the current-limiting resistor R1 and the magnetic core coil to form a loop. The second coil of the mutual inductance coil and the lower winding of the secondary-side induction coil of the high-frequency transformer have opposite terminals and are connected in series in the circuit.

[0025] like Figure 2As shown, in this embodiment, the magnetic core coil 1 is made of a high-permeability magnetic material with a specific shape. Its shape depends on the internal structure of the actual circuit and can be formed in different shapes according to the spatial distribution in the actual circuit. The key point is that the magnetic core containing the coil is located within this circuit, so that the magnetic flux density can change accordingly when the main circuit current changes. The magnetic core is made of a high-permeability magnetic material, such as ferrite or amorphous materials. In this embodiment, the magnetic core coil 1 is located below the lower winding of the secondary induction coil 3 of the high-frequency transformer. Placing the specifically shaped magnetic core coil below the main power transformer and in close contact with the magnetic core of the secondary induction coil 3 of the high-frequency transformer strengthens the external magnetic field, thereby achieving the reed switch magnetic attraction AT value. The secondary induction coil 3 of the high-frequency transformer and the primary mutual inductance coil are connected in series with opposite terminals, and the superposition of the induced currents from the primary side and the main transformer is used to control the reed switch attraction. This ensures that any abnormality in the input or output can trigger a disconnection protection function. The reed switch 2 passes through the magnetic core coil 1 and is embedded within it.

[0026] Based on the closed-loop current data of the magnetic core coil, the current is reduced to less than this data during normal circuit operation by selecting the current-limiting resistor R1. At this time, the magnetic core coil does not operate, the reed switch K1 remains normally closed, and the circuit operates normally. When an abnormality occurs in the circuit, whether it is an abnormality in the primary coil circuit or the output circuit, anything that causes a change in the main transformer magnetic field, thereby causing a change in the induced electromotive force, will cause a change in the equivalent constant current source. When the output current of the constant current source is greater than the closed-loop current data of the magnetic core coil, the magnetic core coil starts to work, causing the reed switch K1 to open, and the circuit is protected.

[0027] A reed switch is connected in series in the secondary output circuit to control the presence or absence of current on the load by switching it on and off. When the input current increases, the current in the primary side mutual inductance coil also increases, and this current, combined with the current in the main transformer induction coil, causes the current in the magnetic core coil circuit to decrease. Consequently, the magnetic field weakens and falls below the reed switch's closing threshold, causing the reed switch to open and thus protecting the output load. The current-limiting resistor in the circuit limits the current magnitude to prevent excessive current from exceeding the coil's carrying capacity.

[0028] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principle of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A protection circuit based on reed switch switching, used to protect a power switching circuit, the power switching circuit including an input circuit, an output circuit, a high-frequency transformer and a reed switch, wherein the primary induction coil of the high-frequency transformer is connected in series in the input circuit, and the secondary induction coil of the high-frequency transformer and the reed switch are connected in series in the output circuit, characterized in that: The protection circuit is used to control the turn-off of the reed switch K1; the protection circuit includes a magnetic core coil, a current-limiting resistor R1 and a mutual inductance coil. The first coil of the mutual inductance coil is connected in series in the input circuit, and the second coil of the mutual inductance coil, the secondary side induction coil of the high-frequency transformer, the magnetic core coil and the current-limiting resistor R1 form a loop. Under normal conditions, the reed switch K1 remains closed. When the power switch circuit malfunctions, the mutual inductance currents on the primary and secondary sides of the high-frequency transformer are superimposed, the magnetic field strength of the magnetic core coil decreases, and the reed switch K1 is opened.

2. The protection circuit based on reed switch switching according to claim 1, characterized in that: The primary winding of the high-frequency transformer includes an upper winding and a lower winding. The first winding of the mutual inductance coil is connected in series in the input main circuit of the upper winding of the primary winding. The secondary winding of the high-frequency transformer also includes an upper winding and a lower winding. The upper winding of the secondary winding, the reed switch K1, and the load form the output circuit. The second winding of the mutual inductance coil, the lower winding of the secondary winding, the current-limiting resistor, and the magnetic core coil form a loop.

3. A protection circuit based on reed switch switching according to claim 2, characterized in that: The lower winding of the secondary induction coil of the high-frequency transformer is used to sense electromagnetic changes in the high-frequency transformer, thereby sensing changes in the primary current of the high-frequency transformer. The second coil of the mutual inductance coil is used to sense changes in the primary current of the high-frequency transformer. The current changes induced by the secondary induction coil of the high-frequency transformer and the current changes induced by the second coil of the mutual inductance coil are superimposed to form a changing constant current source. The superimposed constant current source is connected in series with the current limiting resistor R1 and the magnetic core coil to form a circuit.

4. A protection circuit based on reed switch switching according to claim 2, characterized in that: The magnetic core coil is made of a highly magnetic material and is located below the lower winding of the induction coil on the secondary side of the high-frequency transformer.

5. A protection circuit based on reed switch switching according to claim 2, characterized in that: The reed switch passes through the magnetic core coil and is embedded inside the magnetic core coil.

6. A protection circuit based on reed switch switching according to claim 2, characterized in that: The second coil of the mutual inductance coil is opposite to the lower winding of the induction coil on the secondary side of the high-frequency transformer, and is connected in series.

7. A protection circuit based on reed switch switching according to claim 3, characterized in that: When the circuit is operating normally, the constant current source formed by the superposition of the current induced by the second coil of the mutual inductance coil and the induction coil on the secondary side of the high-frequency transformer is less than the closed current of the magnetic core coil. At this time, the magnetic core coil does not operate, the reed switch K1 remains normally closed, and the circuit operates normally. When an abnormality occurs in the circuit, the constant current source formed by the superposition of the current induced by the second coil of the mutual inductance coil and the induction coil on the secondary side of the high-frequency transformer is greater than the closed current of the magnetic core coil. At this time, the magnetic core coil starts to work, the reed switch K1 opens, and the circuit is protected.

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