Active fuse and application circuit thereof

Abstract

The utility model provides an active fuse and an application circuit thereof, and relates to the technical field of circuit protection, the active fuse comprises a first fuse wire, a heating element and a detection unit, the detection unit comprises a thermistor, and the thermistor is installed on one side of the first fuse wire through a heat conduction support. A first groove used for placing a first fuse wire and a second groove used for placing a thermistor are arranged in front of and behind the heat conduction support, a shell is further arranged outside the heat conduction support, and the shell is buckled with the first fuse wire and accommodates the thermistor and the heat conduction support in the shell. The first fuse wire, the heating element and the detection unit are all provided with electrode pins extending to the outside of the active fuse, and the first fuse wire, the heating element and the detection unit are all electrically connected with the MCU. The temperature of the first fuse wire can be obtained in real time through the thermistor, the MCU obtains the resistance of the first fuse wire at the moment according to the temperature-resistance curve of the first fuse wire, the current passing through the first fuse wire is obtained through the resistance and the current, and real-time monitoring of the current is achieved.

Description

Technical Field

[0001] The utility model relates to the field of circuit protection, in particular to an active fuse and an application circuit thereof. Background Art

[0002] An active fuse is a fuse protection device with an active control function. It can not only achieve overload protection through the traditional thermal fuse principle, but also actively cut off the circuit through electronic control methods to prevent damage caused by circuit overload, short circuit or other abnormal conditions. Compared with traditional fuses or circuit breakers, active fuses provide a more accurate and flexible protection mechanism, which can respond quickly according to the real-time status of the circuit. They are widely used in home energy storage, new energy equipment, base station power supply and other fields.

[0003] Active fuses need to monitor current in real time to quickly respond to overload or short-circuit conditions. However, due to changes in temperature, load and other factors, the current at both ends of the active fuse cannot be directly measured. At the same time, as a one-time use product, if detection resistors and detection sensors are used for current detection, the overall cost will undoubtedly increase. Utility Model Content

[0004] In order to overcome the defects of the prior art, the technical problem to be solved by the present invention is to propose an active fuse and its application circuit, adopting the following technical solutions:

[0005] An active fuse includes a main circuit unit and a control unit, wherein the main circuit unit includes a first fuse, the control unit includes a heating element for blowing the first fuse, and also includes a detection unit, wherein the detection unit includes a thermistor, and the thermistor is installed on one side of the first fuse through a heat-conducting bracket.

[0006] As a further improvement, one side of the heat-conducting bracket is provided with a first groove for accommodating the first fuse, and the other side is provided with a second groove for accommodating the thermistor.

[0007] As a further improvement, one side of the heat-conducting bracket is a semicircular arc surface to form the first groove, and the second groove includes a circular groove and a guide groove.

[0008] As a further improvement, it also includes a shell, one side of the shell is provided with an opening, the opening is provided with an elastic buckle for clamping the first fuse, the thermistor and the heat-conducting bracket are accommodated inside the shell, and the shell is provided with a yield groove matching the guide groove.

[0009] As a further improvement, the material of the thermally conductive bracket is alumina ceramic, and the outer surfaces of the first groove and the second groove are coated with thermally conductive silicone grease.

[0010] As a further improvement, the control unit further includes a second fuse, which is connected in series with the heating element. The heating element is also used to blow the second fuse, and the blowing temperature of the second fuse is greater than the blowing temperature of the first fuse.

[0011] As a further improvement, the heating element and the thermistor are arranged opposite to each other on both sides of the first fuse.

[0012] As a further improvement, the control unit is serially connected with an NMOS transistor as a switch element.

[0013] As a further improvement, the main circuit unit, the control unit and the detection unit are all provided with electrode pins extending to the outside of the shell.

[0014] The utility model further provides an application circuit of an active fuse, comprising an active fuse as described in any one of the above items, and also comprising an MCU, the main circuit unit is electrically connected to the MCU, the control unit is electrically connected to the MCU to form a control circuit, and the detection unit is electrically connected to the MCU to form a detection circuit.

[0015] Compared with the prior art, the beneficial effects of the utility model are:

[0016] First, compared with the traditional active fuse, the utility model adds a detection unit, which includes a thermistor, which is installed on one side of the first fuse through a heat-conducting bracket. The temperature of the first fuse can be obtained in real time through the thermistor, and then the resistance of the first fuse at this time can be obtained according to the temperature-resistance curve of the first fuse. The voltage across the first fuse is easy to measure, and the current flowing through the first fuse at any time can be quickly obtained through Ohm's law. The above method indirectly monitors the current in real time, simplifies the circuit design of current detection, does not require a complex current measurement circuit, can respond to circuit abnormalities in a timely manner, and reduces the potential safety hazards in direct measurement.

[0017] Secondly, in the utility model, the thermistor is installed on one side of the first fuse through a heat-conducting bracket. One side of the heat-conducting bracket is concave to form a semicircular first groove, and its groove shape matches the shell of the first fuse. The other side of the heat-conducting bracket is provided with a circular groove for placing the thermistor and a guide groove for placing the lead wire. The notches of the first groove and the second groove are both provided with elastic buckles. When in use, the outer surfaces of the first groove and the second groove are also coated with thermal grease. The heat-conducting bracket realizes efficient heat conduction from the first fuse to the thermistor, ensuring that the thermistor can accurately and quickly reflect the temperature change of the fuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the implementation mode of the utility model, the following is a brief introduction to the drawings required for use in the implementation mode. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a schematic diagram of the internal circuit structure of an embodiment of the utility model;

[0020] Figure 2 This is a circuit connection diagram of an embodiment of the utility model;

[0021] Figure 3 This is a schematic diagram of the internal circuit structure of another embodiment of the utility model;

[0022] Figure 4 It is a schematic diagram of the assembly of the first fuse and the thermistor of the utility model;

[0023] Figure 5 It is a structural schematic diagram of the housing of the utility model;

[0024] Figure 6 It is a structural schematic diagram of the heat-conducting bracket of the utility model.

[0025] Reference numerals:

[0026] 1-first fuse; 2-heating element; 3-thermistor; 4-thermal conductive bracket; 5-housing; 6-second fuse; 7-NMOS transistor;

[0027] 41-first groove; 42-second groove; 421-circular groove; 422-guide groove;

[0028] 51-elastic buckle; 52-gap slot. DETAILED DESCRIPTION

[0029] In order to facilitate understanding by those skilled in the art, the structure of the present invention is further described in detail with reference to the accompanying drawings:

[0030] In the description of the present invention, the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. The terms "upper", "lower", "side", "end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0031] like Figure 1 and Figure 2 As shown, the present application provides an active fuse, which includes a main circuit unit and a control unit. The main circuit unit includes a first fuse 1. The control unit includes a heating element 2 for melting the first fuse 1. It also includes a detection unit. The detection unit includes a thermistor 3. The thermistor 3 is installed on one side of the first fuse 1 through a heat-conducting bracket 4.

[0032] The main circuit unit, the control unit and the detection unit are all provided with electrode pins extending to the outside of the shell.

[0033] like Figure 3 As shown, the present application also provides an application circuit of an active fuse, including the above-mentioned active fuse and an MCU, the main circuit unit is electrically connected to the above-mentioned MCU, the above-mentioned control unit is electrically connected to the above-mentioned MCU to form a control circuit, and the above-mentioned detection unit is electrically connected to the above-mentioned MCU to form a detection circuit.

[0034] In a specific embodiment, the first fuse 1 is an alloy-type temperature fuse, which uses a fusible alloy as a temperature-sensing component. When the temperature reaches 150°C, it melts and cuts off the circuit to achieve circuit protection. The heating element 2 is an electric heating wire. When the fuse signal is received, the electric heating wire is energized and the temperature reaches above 150°C. The temperature of the first fuse 1 rises rapidly under the influence of the electric heating wire. When the temperature rises to 150°C, it melts and cuts off the circuit. The thermistor 3 is an NTC thermistor. The resistance value of the NTC thermistor changes significantly with temperature, which can accurately reflect the temperature change of the first fuse 1 and transmit the temperature change data to the MCU. According to the temperature-resistance curve pre-measured by the first fuse 1, the resistance of the first fuse 1 at this temperature can be obtained, and the voltage across the first fuse 1 can be transmitted to the MCU through an analog-to-digital converter (not shown in the figure). The MCU can quickly obtain the current flowing through the first fuse 1 at any time based on the obtained voltage and resistance data. When the current exceeds the set value, the MCU turns on the control loop to heat the electric heating wire and melt the first fuse 1. Furthermore, by monitoring the current change of the first fuse 1 in real time, the MCU can turn on the control loop when the current changes abnormally, such as a sudden increase in current, to cause the first fuse 1 to blow.

[0035] like Figure 3 and Figure 5 As shown, a first groove 41 for accommodating the first fuse 1 is disposed on one side of the heat-conducting bracket 4 , and a second groove 42 for accommodating the thermistor 3 is disposed on the other side thereof.

[0036] In a specific embodiment, the first fuse 1 is cylindrical, the thermistor 3 is oblate, and one side of the thermally conductive bracket 4 is a semicircular arc surface, forming the first groove 41, which can better fit the outer surface of the first fuse 1 and facilitate heat conduction. The second groove 42 includes a circular groove 421 and a guide groove 422, wherein the circular groove 421 is used to place the oblate thermistor 3, and the guide groove 422 is used to place the wire connected to the thermistor 3. The thermally conductive bracket 4 is installed on the side of the first fuse 1 away from the heating element 2 to avoid being affected by the heating element 2.

[0037] like Figure 4 and Figure 5 As shown, the heat-conducting bracket 4 also includes a shell 5. In a specific embodiment, the inner shape of the shell 5 matches the outer shape of the heat-conducting bracket 4, and an opening is provided on one side, and two elastic buckles 51 are respectively provided on the upper and lower edges of the opening, and a clearance groove 52 matching the position of the guide groove 422 is provided at the lower part of the shell 5.

[0038] In a specific embodiment, the clearance groove 52 is a strip-shaped opening provided at the bottom of the shell 5 and opened along the insertion direction. When the shell 5 is inserted, the first fuse 1 is installed in the first groove 41, the thermistor 3 is installed in the circular groove 421, and the wire of the thermistor 3 extends from the guide groove 422. The shell 5 is inserted with the opening facing the second groove 42, and the thermistor 3 and the thermal conductive bracket 4 are stored inside the shell 5, and are buckled with the first fuse 1 through the elastic buckle 51 at the opening. This structure can ensure that the thermistor 3, the thermal conductive bracket 4 and the first fuse 1 are tightly fitted, and realizes efficient heat conduction of the first fuse 1 to the thermistor 3, ensuring that the thermistor 3 can accurately and quickly reflect the temperature change of the first fuse 1.

[0039] Furthermore, the material of the heat-conducting bracket 4 is alumina ceramics with good thermal conductivity, and the outer surfaces of the first groove 41 and the second groove 42 are coated with thermal grease to further improve the thermal conductivity efficiency.

[0040] like Figure 1 and Figure 2 As shown, the control unit also includes a second fuse 6, which is connected in series with the heating element 2, and the fusing temperature of the second fuse 6 is greater than the fusing temperature of the first fuse 1. The second fuse 6 is arranged on the side of the heating element 2 away from the first fuse 1. After the heating element 2 is heated, the first fuse 1 and the second fuse 6 will be blown in sequence. More specifically, when the control loop is turned on, the heating element 2 starts to heat up so that the first fuse 1 is blown first, and then continues to heat so that the second fuse 6 is blown, thereby disconnecting the control loop.

[0041] In a specific embodiment, the control unit is composed of an NMOS transistor 7 as a switch element, the source of the NMOS transistor 7 is grounded, the drain is connected to the control loop power supply, and the gate is connected to the signal control terminal of the MCU. When the MCU receives the fuse signal, a high level signal is sent to the gate of the NMOS transistor 7 to turn it on, thereby turning on the control loop.

[0042] like Figure 3 As shown, in another embodiment, the heating element 2 is composed of two parallel heating wires, and the two heating wires are respectively used to fuse the first fuse 1 and the second fuse 6. By providing two heating wires, the flexibility of the arrangement of the internal components of the active fuse is increased.

[0043] The above description is only the preferred implementation of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. An active fuse, comprising a main circuit unit and a control unit, wherein the main circuit unit comprises a first fuse (1), and the control unit comprises a heating element (2) for melting the first fuse (1), characterized in that: It also comprises a detection unit, the detection unit comprising a thermistor (3), the thermistor (3) being mounted on one side of the first fuse (1) via a heat-conducting bracket (4).

2. An active fuse as claimed in claim 1, characterized in that: One side of the heat-conducting bracket (4) is provided with a first groove (41) for accommodating the first fuse (1), and the other side is provided with a second groove (42) for accommodating the thermistor (3).

3. An active fuse as claimed in claim 2, characterized in that: One side of the heat-conducting bracket (4) is a semicircular arc surface, forming the first groove (41), and the second groove (42) comprises a circular groove (421) and a guide groove (422).

4. An active fuse as claimed in claim 3, characterized in that: The invention also comprises a shell (5), one side of which is provided with an opening, the opening being provided with an elastic buckle (51) for clamping the first fuse (1), the thermistor (3) and the heat-conducting bracket (4) being accommodated inside the shell (5), and the shell (5) being provided with a clearance groove (52) matching the guide groove (422).

5. An active fuse as claimed in claim 4, characterized in that: The material of the heat-conducting bracket (4) is alumina ceramic, and the outer surfaces of the first groove (41) and the second groove (42) are coated with heat-conducting silicone grease.

6. An active fuse as claimed in claim 1, characterized in that: The control unit further comprises a second fuse (6), the second fuse (6) being connected in series with the heating element (2), the heating element (2) being further used to cause the second fuse (6) to melt, and the melting temperature of the second fuse (6) being greater than the melting temperature of the first fuse (1).

7. An active fuse as claimed in claim 6, characterized in that: The heating element (2) and the thermistor (3) are arranged opposite to each other on two sides of the first fuse (1).

8. An active fuse as claimed in claim 1, characterized in that: The control unit is serially connected with an NMOS transistor (7) as a switch element.

9. An active fuse as claimed in claim 1, characterized in that: The main circuit unit, the control unit and the detection unit are all provided with electrode pins extending to the outside of the shell.

10. An application circuit of an active fuse, characterized in that: It comprises an active fuse as described in any one of claims 1 to 9, and also comprises an MCU, the main circuit unit is electrically connected to the MCU, the control unit is electrically connected to the MCU to form a control circuit, and the detection unit is electrically connected to the MCU to form a detection circuit.

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