Thin film capacitor protection circuit and device

Abstract

The utility model discloses a thin-film capacitor protection circuit and device, relates to the technical field of electronics, and aims to overcome the defect that the whole thin-film capacitor needs to be replaced because a fuse wire or a fuse inside the thin-film capacitor is fused due to over-current, over-voltage, heating and the like in the circuit. The thin-film capacitor protection circuit comprises a thin-film capacitor, a piezoresistor and a thermistor, the piezoresistor and the thin film capacitor are arranged in parallel to form a branch; the input end of the thermistor is electrically connected with the power supply output end, the output end of the thermistor is electrically connected with the input end of the branch circuit, and the output end of the branch circuit is electrically connected with the power supply input end.

Description

Technical Field

[0001] The utility model relates to the field of electronic technology, and more particularly to a film capacitor protection circuit and device. Background Art

[0002] Film capacitors are mainly used in electronics, home appliances, communications, electricity, electrified railways, hybrid vehicles, wind power generation, solar power generation and other industries. The current protection method for film capacitors with a nominal voltage below 1000V is to connect a fuse or fuse in series inside the film capacitor. The equivalent circuit diagram of the film capacitor protection circuit is as follows Figure 1 As shown in the figure, C represents a film capacitor, and FU represents a fuse or a cutout connected in series with the film capacitor C. In actual applications, when a relatively large current flows through the circuit, it generates a lot of heat, which may cause the fuse or the cutout to blow.

[0003] In actual applications, since the fuse or fuse is cast inside the film capacitor, if the fuse or fuse used to protect the film capacitor is blown during use, the entire film capacitor must be replaced in time; when the film capacitor loses its protection device function, once overcurrent or overheating occurs again, the entire circuit system will fail. If the fuse or fuse is in a virtual blown state, an arc flash will cause the entire film capacitor to explode. Utility Model Content

[0004] The present invention provides a film capacitor protection circuit and device to solve the problem that the internal fuse or fuse of the film capacitor blows due to overcurrent, overvoltage, heating, etc. in the circuit, and the entire film capacitor must be replaced.

[0005] The embodiment of the utility model provides a thin film capacitor protection circuit, comprising: a thin film capacitor, a varistor and a thermistor;

[0006] The varistor and the film capacitor are connected in parallel to form a branch circuit;

[0007] The input end of the thermistor is electrically connected to the output end of the power supply, the output end of the thermistor is electrically connected to the input end of the branch, and the output end of the branch is electrically connected to the input end of the power supply.

[0008] The embodiment of the utility model provides a film capacitor protection device, comprising a film capacitor with an annular hollow structure, a thermistor, a varistor and a film capacitor housing;

[0009] The film capacitor is located in the film capacitor housing, and an epoxy resin material is provided between the film capacitor and the film capacitor housing;

[0010] The varistor is fixed in the hollow structure of the film capacitor by epoxy resin material, one end of the varistor is connected to the bottom of the film capacitor, and the other end extends out of the upper end of the film capacitor shell through a lead wire;

[0011] The thermistor is arranged above the film capacitor, one end of the thermistor is connected to the top of the film capacitor, and the other end extends out of the upper end of the film capacitor shell through a lead.

[0012] Preferably, an epoxy resin material is provided between the upper surface of the film capacitor and the upper surface of the film capacitor housing; and an epoxy resin material is provided between the lower surface of the film capacitor and the lower surface of the film capacitor housing.

[0013] In summary, the embodiments of the present invention provide a thin film capacitor protection circuit and device, the protection circuit comprising: a thin film capacitor, a varistor, and a thermistor; the varistor is arranged in parallel with the thin film capacitor to form a branch circuit; the input end of the thermistor is electrically connected to the output end of the power supply, the output end of the thermistor is electrically connected to the input end of the branch circuit, and the output end of the branch circuit is electrically connected to the input end of the power supply. When overvoltage or overcurrent occurs in the circuit, the varistor in parallel with the thin film capacitor in the protection circuit can start protection; if overheating occurs in the circuit, the thermistor in series with the thin film capacitor can start protection. The varistor and the thermistor have self-recovery capabilities, and the entire thin film capacitor does not need to be replaced due to a single overvoltage, overcurrent, or overheating in the circuit, thereby solving the problem of having to replace the entire thin film capacitor due to the internal fuse or fuse blowing caused by overcurrent, overvoltage, heating, etc. in the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 A schematic structural diagram of a film capacitor protection device provided in an embodiment of the present utility model;

[0016] Figure 2 A schematic diagram of a thin film capacitor protection circuit structure provided by an embodiment of the present utility model;

[0017] Among them, film capacitor ~11, varistor ~12, thermistor ~13, film capacitor shell ~14, epoxy resin material ~15. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] Figure 1 A schematic structural diagram of a film capacitor protection device provided in an embodiment of the present utility model; Figure 2 A schematic diagram of a thin film capacitor protection circuit structure provided by an embodiment of the present utility model;

[0020] The following Figure 1 and Figure 2 Taking the example, the film capacitor protection circuit and the film capacitor protection device provided by the embodiments of the present invention are described in detail.

[0021] like Figure 1 As shown, the film capacitor protection device provided by the embodiment of the present invention includes a film capacitor 11 with an annular hollow structure and a film capacitor shell 14 from the inside to the outside, wherein a varistor 12 and a thermistor 13 are respectively arranged inside and on the upper part of the film capacitor with the annular hollow structure.

[0022] Specifically, the film capacitor is located in the film capacitor housing, and epoxy resin material is arranged between the film capacitor and the film capacitor housing; further, since the film capacitor is an annular hollow structure, in the given embodiment, a varistor is arranged in the annular hollow structure, one end of the varistor is welded to the bottom of the film capacitor through a lead, and the other end extends out of the upper end of the film capacitor housing through a lead. It should be noted that in addition to the varistor, the hollow part of the film capacitor with an annular hollow structure is also filled with epoxy resin material, that is, the varistor is fixed in the annular hollow part through the epoxy resin material; further, a thermistor is also arranged above the film capacitor, one end of the thermistor is welded to the top of the film capacitor, and the other end extends out of the upper end of the film capacitor housing through a lead.

[0023] It should be noted that while epoxy resin material is provided between the film capacitor and the film capacitor casing, since one end of the varistor is welded to the bottom of the film capacitor, in order to protect the welding point, epoxy resin material is also provided between the bottom of the film capacitor and the lower surface of the film capacitor casing; correspondingly, since the thermistor is provided above the film capacitor, epoxy resin material is also provided between the top of the film capacitor and the upper surface of the film capacitor casing.

[0024] like Figure 2 As shown, an embodiment of the present invention provides a thin film capacitor protection circuit, which includes a thin film capacitor 11, a varistor 12 and a thermistor 13.

[0025] In practical applications, the varistor and the film capacitor are arranged in parallel, and then the varistor and the film capacitor form a branch; further, the branch formed by the varistor and the film capacitor has an output end electrically connected to the power input end, an input end electrically connected to the input end of the thermistor, and the input end of the thermistor is electrically connected to the power output end.

[0026] In actual applications, when overvoltage or overcurrent occurs in a circuit equipped with a thin film capacitor, because the thin film capacitor is equipped with a protection circuit, the varistor connected in parallel with the film capacitor in the protection circuit can start protection. If overheating occurs in the circuit, the thermistor connected in series with the film capacitor can also start protection, avoiding the problem of internal fuse of the film capacitor caused by voltage, heat and other reasons; furthermore, the varistor and the thermistor have self-recovery capabilities, and they will not require the replacement of the entire film capacitor due to a single overvoltage, overcurrent or overheating in the circuit, thereby solving the problem of the entire film capacitor having to be replaced due to the internal fuse or fuse blowing caused by overcurrent, overvoltage, heat and other reasons in the circuit.

[0027] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0028] Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A film capacitor protection circuit, characterized in that: include: film capacitors, varistors, and thermistors; The varistor and the film capacitor are connected in parallel to form a branch circuit; The input end of the thermistor is electrically connected to the output end of the power supply, the output end of the thermistor is electrically connected to the input end of the branch, and the output end of the branch is electrically connected to the input end of the power supply.

2. A film capacitor protection device, characterized in that: Including film capacitors, thermistors, varistors and film capacitor shells with annular hollow structures; The film capacitor is located in the film capacitor housing, and an epoxy resin material is provided between the film capacitor and the film capacitor housing; The varistor is fixed in the hollow structure of the film capacitor by epoxy resin material, one end of the varistor is connected to the bottom of the film capacitor, and the other end extends out of the upper end of the film capacitor shell through a lead wire; The thermistor is arranged above the film capacitor, one end of the thermistor is connected to the top of the film capacitor, and the other end extends out of the upper end of the film capacitor shell through a lead.

3. The device according to claim 2, wherein An epoxy resin material is provided between the upper surface of the film capacitor and the upper surface of the film capacitor shell; and an epoxy resin material is provided between the lower surface of the film capacitor and the lower surface of the film capacitor shell.

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