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1. (WO2019063629) CURRENT TRANSFORMER
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Description

Current transformer

Technical Field

The present invention relates to the technical field of power semiconductors, and in particular to a current transformer .

Background Art

Current transformers are electrical appliances that change the voltage, frequency, phase and the other electric quantities or characteristics of power supply systems. A current transformer generally comprises a rectifier for converting alternating-current into direct-current (AC/DC) , a direct-current link (DC-link) with decoupling and filtering functions, and an inversion unit for converting direct-current into alternating-current (DC/AC) . The power conversion function of the current transformer is implemented by means of a specific circuit topology constituted of power semiconductor devices . Power semiconductor devices generate a significant amount of heat when working, and a good heat dissipation is thus required to ensure the working performance thereof.

At present, a specific cooling technique is generally used to realize the heat dissipation of the power semiconductor devices in the current transformer. The heat dissipation method can comprise natural cooling of a metal heat dissipator, enforcement of air cooling or liquid cooling by means of a combination of the metal heat dissipator and a fan, etc. For universal industrial current transformers which are price-sensitive, air cooling is the most extensively acceptable method .

In the prior art, power semiconductor devices constituting a current transformer are generally arranged in an in-line cooling manner. Fig. 1 is a schematic diagram of an in-line cooling manner of a current transformer in the prior art. In Fig. 1, an inversion unit 11, a rectifier unit 12 and a direct-current link unit 13 are sequentially connected in series relative to cooling air. The cooling air flows through the inversion unit 11, the rectifier unit 12 and the direct-current link unit 13 one after another. In the in-line cooling arrangement manner, a fan can be located at the bottom thereof to serve as an air blower or at the top to suck in air.

However, the inversion unit 11 and the rectifier unit 12 in the in-line cooling manner have an in-line cooling air duct, thereby leading to a large air resistance and a low cooling efficiency. Moreover, the rectifier unit 12 is located downstream of the cooling air duct, thereby causing a poor cooling effect.

Summary of the Invention

The embodiments of the present invention propose a current transformer .

The technical solutions of the embodiments of the present invention are as follows :

a current transformer, comprising:

a cabinet,

a rectifier assembly disposed at one side of the cabinet in a first direction, and

an inversion filter assembly disposed at the other side of the cabinet in the first direction,

wherein the rectifier assembly and the inversion filter assembly are provided with mutually independent cooling air ducts .

It can be seen that the rectifier assembly and the inversion filter assembly, which constitute the current transformer, are respectively provided with mutually independent cooling air ducts, and their respective air resistances are relatively small, and the cooling efficiency is correspondingly improved, such that both the rectifier assembly and the inversion filter assembly can have a good cooling effect. In addition, an inversion unit and a direct-current link unit, which constitute the current transformer, are integrated into one inversion filter assembly, such that a modularized and compact current transformer can be achieved.

In one embodiment :

the cooling air duct of the rectifier assembly is parallel to the first direction, and the cooling air duct of the inversion filter assembly is parallel to a second direction, which is different from the first direction.

It can be seen that by arranging the cooling air duct of the rectifier assembly to be parallel to the first direction, and arranging the cooling air duct of the inversion filter assembly to be parallel to a second direction which is different from the first direction, it is ensured that the cooling air duct of the rectifier assembly and the cooling air duct of the inversion filter assembly do not interfere with each other.

In one embodiment :

there are 3n inversion filter assemblies, the inversion filter assemblies are disposed along the first direction, and the cooling air ducts of the inversion filter assemblies are parallel to each other, with n being a positive integer.

It can be seen that by arranging 3n inversion filter assemblies that are disposed in parallel, a plurality of paths of three-phase outputs can be provided.

In one embodiment, n is equal to 1 or 2.

It can be seen that the embodiments of the present invention may support one path of a three-phase output, and may also support two paths of a three-phase output, and thus have a wide application.

In one embodiment, the current transformer further comprises :

a common pipeline extending, along the first direction, through the air outlet of the cooling air duct of each of the inversion filter assemblies.

It can be seen that the embodiments of the present invention can make it convenient to gather gas streams of the inversion filter assemblies by arranging a common pipeline for the inversion filter assemblies, so as to facilitate centralized processing of the gas streams.

In one embodiment, the rectifier assembly comprises:

a heat dissipator;

a fan mounted at one side of the heat dissipator in the first direction;

a three-phase input busbar mounted on a side portion of the heat dissipator in a second direction, which is different from the first direction; and

a rectifier bridge mounted in the three-phase input busbar .

It can be seen that the embodiments of the present invention further propose a rectifier assembly that has a compact structure and provides a cooling function by itself, thereby facilitating assembly of same into the current transformer .

In one embodiment, the rectifier bridge is a half rectifier bridge or a full rectifier bridge.

It can be seen that there are multiple examples of the rectifier bridge in the embodiments of the present invention, and same can be flexibly configured based on requirements.

In one embodiment, the inversion filter assembly comprises :

a heat dissipator;

a fan mounted at one side of the heat dissipator in the second direction;

a filter capacitor located, in a third direction which is different from the first direction and the second direction, at one side of the heat dissipator;

a single-phase output busbar, which is located, in a direction which is different from the third direction, at the same side of the heat dissipator as the filter capacitor, and is spaced apart from the filter capacitor in the second direction;

an insulated gate bipolar transistor located, in a direction which is different from the first direction, at one side of the heat dissipator; and

a laminated busbar located, in a direction which is different from the first direction, at the same side of the heat dissipator as the insulated gate bipolar transistor.

It can be seen that the embodiments of the present invention further propose an inversion filter assembly that has a compact structure and provides a cooling function by itself, thereby facilitating assembly of same into the current transformer .

In one embodiment, the inversion filter assembly further comprises: a current sensor spaced apart from the single-phase output busbar in the first direction.

It can be seen that, by arranging the current sensor in the inversion filter assembly, the inversion filter assembly have an integrated current detection function.

Brief Description of the Drawings

Fig. 1 is a schematic diagram of an in-line cooling manner of a current transformer in the prior art.

Fig. 2 is an exemplary stereoscopic structural diagram of a current transformer according to the embodiments of the present invention.

Fig. 3 is an exemplary stereoscopic structural diagram of a rectifier assembly according to the embodiments of the present invention.

Fig. 4 is an exemplary stereoscopic structural diagram of an inversion filter assembly according to the embodiments of the present invention.

Fig. 5 is a side view of an exemplary current transformer according to the embodiments of the present invention.

Fig. 6 is a side view of a common air duct of an exemplary current transformer according to the embodiments of the present invention .

The reference signs are as follows

Numerals Meaning

11 Inversion unit (prior art)

12 Rectifier unit (prior art)

13 Direct-current link unit (prior art)

20 Cabinet

21 Rectifier assembly

22 Inversion filter assembly

23 Common air duct

24 Adjustable air baffle plate

211 Fan

212 Three-phase input busbar

213 Rectifier bridge

214 Heat dissipator

215 Bus terminal

220 Absorption capacitor

221 Filter capacitor

222 Laminated busbar

223 Fan

224 Heat dissipator

225 Current sensor

226 Insulated gate bipolar transistor

227 Single-phase output busbar

228 First bus terminal

229 Second bus terminal

Detailed Description of Embodiments

In order to make the technical solutions and advantages of the present invention clearer, the present invention is further illustrated below in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the present invention in an illustrative manner, and are not intended to limit the scope of protection of the present invention.

For the sake of concise and intuitive description, the solutions of the present invention are illustrated below by describing several representative embodiments. Numerous details in the embodiments are merely used for helping to understand the solutions of the present invention. However, the implementation of the technical solutions of the present invention may not be limited to these details. In order to avoid unnecessarily obscuring the solutions of the present invention, some embodiments are not described in detail, and only the frame thereof is provided. Hereinafter, "comprise" means "comprising, but not being limited to", and "according to..." means "at least according to, but not limited to only being according to...". Due to the structure of the Chinese language, when the number of one component is not particularly stated below, this means that there may be one or more of the component, or it can be understood as meaning that there is at least one of same.

In the embodiments of the present invention, an inversion unit and a direct-current link unit, which constitute the current transformer, are integrated into one inversion filter assembly, such that a modularized and compact current transformer is achieved. Moreover, the rectifier assembly and the inversion filter assembly in the current transformer are respectively provided with mutually independent cooling air ducts, and their respective air resistances are relatively small, and the cooling efficiency is improved, such that the rectifier assembly and the inversion filter assembly can respectively have a good cooling effect.

Fig. 2 is an exemplary structure diagram of a current transformer according to the embodiments of the present invention. In a coordinate system as shown in Fig. 2, a Y-axis direction is a first direction, an X-axis direction is a second direction, and a Z-axis direction is a third direction.

As shown in Fig. 2, the current transformer comprises: a cabinet 20; and

a rectifier assembly 21 disposed at one side of the cabinet 20 in a first direction, and

an inversion filter assembly 22 disposed at the other side of the cabinet 20 in the first direction,

wherein the rectifier assembly 21 and the inversion filter assembly 22 are provided with mutually independent cooling air ducts .

The cabinet 20 has accommodation spaces, with the rectifier assembly 21 being disposed in an accommodation space at one side of the cabinet 20 in the first direction, and the inversion filter assembly 22 being disposed in an accommodation space at the other side of the cabinet 20 in the first direction. The rectifier assembly 21 is used for performing alternating-current to direct-current (AC/DC) conversion processing; and the inversion filter assembly 22 is used for performing direct-current decoupling, filtering, and direct-current to alternating-current (DC/AC) conversion processing.

It can be seen that the embodiments of the present invention integrate an inversion unit and a direct-current link unit, which constitute the current transformer, into one inversion filter assembly, such that a modularized and compact current transformer can be achieved.

Moreover, the rectifier assembly 21 and the inversion filter assembly 22 each contain a heat dissipator and a fan, and are provided with mutually independent cooling air ducts. Preferably, the direction of the cooling air duct of the rectifier assembly 21 is parallel to the first direction (namely, a height direction of the cabinet 20) , and a cooling direction of the inversion filter assembly 22 is parallel to a second direction.

Therefore, the rectifier assembly 21 and the inversion filter assembly 22 each have a relatively small air resistance, and the cooling efficiencies of the rectifier assembly 21 and the inversion filter assembly 22 are thus correspondingly improved, such that both the rectifier assembly 21 and the inversion filter assembly 22 can have a good cooling effect.

In the embodiments of the present invention, there are 3n inversion filter assemblies 22, and the inversion filter assemblies 22 have the same structure and respectively contain their own heat dissipators and fans, with n being a positive integer. The inversion filter assemblies 22 are respectively disposed in parallel along the first direction, and every three inversion filter assemblies 22 can constitute one path of a three-phase output, and the cooling air ducts of the inversion filter assemblies 22 are parallel to each other. Preferably, n can be 1 or 2, such that one path of a three-phase output or two paths of a three-phase output can be provided.

In an exemplary illustration of Fig. 1, there are three inversion filter assemblies 22, and the inversion filter assemblies 22 have the same structure and respectively contain their own heat dissipators and fans. Moreover, the three inversion filter assemblies 22 are vertically disposed according to the same arrangement direction. In this design, cooling air from the environment respectively dissipates the heat of the rectifier assembly 21 and the three inversion filter assemblies 22 by means of their respective heat dissipators, wherein the cooling air ducts of the three inversion filter assemblies 22 are parallel to each other, and the cooling air duct of the rectifier assembly 21 is perpendicular to the cooling air ducts of the three inversion filter assemblies 22.

In Fig. 2, the structure of the current transformer is described by taking three inversion filter assemblies 22 as an example, and a person skilled in the art would recognize that the number of the inversion filter assemblies 22 may also be any number that is an integer multiple of 3, such as 6, 9 or 12.

In one embodiment, the current transformer further comprises :

a common pipeline 23 extending, along the first direction, through the air outlet of the cooling air duct of each of the inversion filter assemblies 22. The common pipeline 23 is used for gathering gas streams which execute a cooling function for the inversion filter assemblies 22. It can be seen that, by arranging a common pipeline for the inversion filter assemblies 22, it is possible to make it convenient to gather gas streams of the inversion filter assemblies, so as to facilitate the centralized processing of the gas streams.

Preferably, each of the inversion filter assemblies 22 further comprises an adjustable air baffle plate 24 disposed at an air outlet. The adjustable air baffle plate 24 makes the air flows discharged, by the inversion filter assemblies 22, to the common pipeline 23 identical, thereby ensuring that the inversion filter assemblies 22 have the same cooling effect.

Based on the above-mentioned description, the embodiments of the present invention further propose an exemplary specific structure of the rectifier assembly 21.

Fig. 3 is an exemplary perspective view of the rectifier assembly 21 according to the embodiments of the present invention. In a coordinate system as shown in Fig. 3, a Y-axis direction is a first direction, an X-axis direction is a second direction, and a Z-axis direction is a third direction.

As shown in Fig. 3, the rectifier assembly 21 comprises: a heat dissipator 214;

a fan 211 mounted at one side of the heat dissipator 214 in the first direction;

a three-phase input busbar 212 mounted on a side portion of the heat dissipator 214 in a second direction, which is different from the first direction; and

a rectifier bridge 213 mounted in the three-phase input busbar 212.

The fan 211 can be implemented as a single fan or a fan group comprising a plurality of fans.

The three-phase input busbar 212 serves as a three-phase input terminal and is used for inputting three-phase power; the rectifier bridge 213 is used for performing rectification processing on the three-phase power input by means of the three-phase input busbar 212; and the heat dissipator 214 and the fan 211 are used for performing cooling processing on the rectifier bridge 213, wherein blades of the fan 211 face heat dissipation fins of the heat dissipator 214. The rectifier bridge 213 may be disposed on one face of the heat dissipator 214, and may also be disposed on two opposite faces of the heat dissipator 214. In Fig. 2, the rectifier bridge 213 is disposed on two opposite faces of the heat dissipator 214. Preferably, the rectifier bridge 213 can comprise a rectifier diode.

The rectifier assembly 21 may further comprise a bus terminal 215 disposed on a connection member wound onto the heat dissipator 214. The rectifier assembly 21 may further comprise another bus terminal (not shown in Fig. 2) wound onto the heat dissipator 214. The bus terminal 215 disposed on the connection member wound on the heat dissipator 214 and another bus terminal wound on the heat dissipator 214 are respectively connected to a common busbar disposed on a mechanism 20.

Preferably, the rectifier bridge 213 can be implemented as a half rectifier bridge or a full rectifier bridge.

By taking the above Fig. 3 as an example, an exemplary specific structure of the rectifier assembly 21 is described in detail. A person skilled in the art would recognize that such description is merely exemplary, and is not intended to limit the scope of protection of the embodiments of the present invention .

Based on the above-mentioned description, the embodiments of the present invention further propose an exemplary specific structure of the inversion filter assembly 22.

Fig. 4 is an exemplary perspective view of the inversion filter assembly according to the embodiments of the present invention. In a coordinate system as shown in Fig. 4, a Y-axis direction is a first direction, an X-axis direction is a second direction, and a Z-axis direction is a third direction.

As shown in Fig. 4, the inversion filter assembly 22 comprises :

a heat dissipator 224;

a fan 223 mounted at one side of the heat dissipator 224 in the second direction;

a filter capacitor 221 located, in a third direction which is different from the first direction and the second direction, at one side of the heat dissipator 224;

a single-phase output busbar 227, which is located, in a direction which is different from the third direction, at the same side of the heat dissipator 224 as the filter capacitor 221, and is spaced apart from the filter capacitor 221 in the second direction;

an insulated gate bipolar transistor 226 located, in a direction which is different from the first direction, at one side of the heat dissipator 224; and

a laminated busbar 222 located, in a direction which is different from the first direction, at the same side of the heat dissipator 224 as the insulated gate bipolar transistor 226.

The filter capacitor 221 and the laminated busbar 222 are commonly used for performing filter processing, and the insulated gate bipolar transistor 226 is used for performing inversion processing. The heat dissipator 224 and the fan 223 are used for performing cooling processing on the insulated gate bipolar transistor 226, wherein blades of the fan 223 face heat dissipation fins of the heat dissipator 224, and the insulated gate bipolar transistor 226 is disposed on the heat dissipator 224. The filter capacitor 221 and the laminated busbar 222 in the inversion filter assembly 22 are located outside the air duct, and thus may not be subjected to the heat effect of the insulated gate bipolar transistor 226.

Preferably, the inversion filter assembly 22 further comprises a current sensor 225, a first bus terminal 228, a second bus terminal 229 and a single-phase output busbar 227. The first bus terminal 228 and the second bus terminal 229 are respectively connected to the common busbar disposed on the mechanism 20. The current sensor 225 is spaced apart from the single-phase output busbar 227 in the first direction, and is used for detecting the value of an inverted current; and the single-phase output busbar 227 serves as a single-phase output terminal, and is used for outputting the value of the inverted current .

In one embodiment, the inversion filter assembly 22 further comprises an adjustable air baffle plate (not shown in Fig. 4) disposed at the air outlet. By adjusting the adjustable air baffle plate, the air flow discharged by the inversion filter assemblies 22 to the common air duct can be adjusted.

By taking the above Fig. 4 as an example, an exemplary specific structure of the inversion filter assembly 22 is described in detail. A person skilled in the art would recognize that such description is merely exemplary, and is not intended to limit the scope of protection of the embodiments of the present invention.

Fig. 5 is a side view of an exemplary current transformer according to the embodiments of the present invention. Fig. 6 is a side view of a common air duct of an exemplary current transformer according to the embodiments of the present invention. In the coordinate systems shown in Figs. 5 and 6, a Y-axis direction is a first direction, an X-axis direction is a second direction, and a Z-axis direction is a third direction.

It can be seen that in the embodiments of the present invention, both the rectifier assembly 21 and each of the inversion filter assemblies 22 respectively have their own independent air ducts, and therefore, the air resistances of their own heat dissipation paths are relatively low, and the fan can work at a relatively high working point. Meanwhile, the cooling air of the rectifier assembly 21 and each of the inversion filter assemblies 22 comes from the surrounding environment, and the basic cooling temperature is lower and the heat dissipation efficiency is high; and the fan and the heat dissipator can be designed economically, thereby also having a cost advantage.

In addition, the embodiments of the present invention integrate an inversion unit and a direct-current link unit, which constitute the current transformer, into one inversion filter assembly, thereby achieving a modularized and compact current transformer. Therefore, a smaller cabinet can be used, and the depth of the cabinet can be fully utilized and the height thereof can be reduced.

In addition, since a modular design is used in the embodiments of the present invention, the inversion filter assembly and the rectifier assembly can be separately mounted and dismantled, such that the current transformer is easily assembled and dismantled, and maintenance thereof is facilitated .

The above-mentioned contents are merely preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be considered to be contained within the scope of protection of the present invention.