Direct current reactor and frequency converter

Abstract

The invention discloses a direct current reactor and a frequency converter. The direct-current reactor comprises a first iron yoke, a second iron yoke, a magnetic core, a first winding and a second winding, wherein the first iron yoke and the second iron yoke are oppositely arranged; the magnetic core is arranged between the first iron yoke and the second iron yoke and comprises a first side plate, a second side plate and a middle plate, the first side plate and the second side plate are arranged on the two sides of the middle plate respectively, the first side plate, the second side plate and the middle plate are arranged at intervals, at least one end of the first side plate is connected with the first iron yoke or the second iron yoke, and at least one end of the second side plate is connected with the second iron yoke. At least one end of the second side plate is connected with the first yoke or the second yoke, one end of the middle plate is connected with the first yoke, the other end of the middle plate is connected with the second yoke, the width of the first side plate is equal to that of the second side plate, and the width of the middle plate is smaller than that of the first side plate; the first winding is wound on the first side plate; the second winding is wound on the second side plate, and the winding directions of the first winding and the second winding are the same. According to the technical scheme, the structural size can be effectively reduced, and the assembling convenience is improved.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a direct current reactor and a frequency converter. Background Art

[0002] There are a large number of nonlinear electrical equipment in the power system, such as commutation equipment, arc furnaces, core equipment, lighting equipment, etc. These equipment will distort the voltage or current waveform during operation, resulting in harmonics in the power grid, including common-mode harmonics and differential-mode harmonics. The presence of common-mode harmonics and differential-mode harmonics can cause malfunction or refusal of relay equipment, increase neutral line current, reduce grid voltage, increase losses, and reduce the service life of transformers.

[0003] In order to suppress differential-mode harmonics and common-mode harmonics, a dual DC reactor is usually installed at the rectifier end of the power input end to suppress harmonics. The current suppression method is to install a separate DC reactor at the positive and negative ends of the DC bus. However, the separate DC reactor occupies a large volume and is not easy to assemble. Summary of the invention

[0004] In view of the defects in the prior art, the present invention provides a DC reactor which can effectively reduce the structure volume and improve the convenience of assembly.

[0005] The present application provides a DC reactor, the DC reactor comprising:

[0006] First Iron Yoke;

[0007] a second iron yoke, wherein the first iron yoke and the second iron yoke are arranged opposite to each other;

[0008] A magnetic core, wherein the magnetic core is arranged between the first iron yoke and the second iron yoke, the magnetic core comprises a first side plate, a second side plate and a middle plate, the first side plate and the second side plate are arranged on both sides of the middle plate, the first side plate and the second side plate are arranged spaced apart from the middle plate, at least one end of the first side plate is connected to the first iron yoke or the second iron yoke, at least one end of the second side plate is connected to the first iron yoke or the second iron yoke, one end of the middle plate is connected to the first iron yoke, and the other end of the middle plate is connected to the second iron yoke, the first side plate and the second side plate have the same width, and the width of the middle plate is smaller than the width of the first side plate;

[0009] A first winding, wherein the first winding is wound on the first side plate, one end of the first winding is connected to a first input cable, and the other end of the first winding is connected to a first output cable;

[0010] The second winding is wound on the second side plate, the first winding and the second winding are wound in the same direction, one end of the second winding is connected to a second input cable, the other end of the second winding is connected to a second output cable, and the first input cable and the second input cable are located on the same side of the magnetic core.

[0011] In one aspect, the width of the middle plate is w, and the width of the first side plate is W1, which satisfies: 20%≤w / W1≤80%.

[0012] In one aspect, 20mm≤w≤80mm.

[0013] In one aspect, one end of the first side plate is connected to the first iron yoke, and a first air gap is formed between the other end of the first side plate and the second iron yoke;

[0014] One end of the second side plate is connected to the first iron yoke, and a second air gap is formed between the other end of the second side plate and the second iron yoke.

[0015] In one aspect, the first side plate includes a first connecting section and a second connecting section, one end of the first connecting section is connected to the first iron yoke, one end of the second connecting section is connected to the second iron yoke, and the first connecting section and the second connecting section are relatively spaced to form a first air gap;

[0016] The second side plate includes a third connecting section and a fourth connecting section, one end of the third connecting section is connected to the first iron yoke, one end of the fourth connecting section is connected to the second iron yoke, and the third connecting section and the fourth connecting section are relatively spaced to form a second air gap.

[0017] In one aspect, the width of the first air gap is defined as d1, the width of the second air gap is defined as d2, the length of the first side plate is defined as L1, and the length of the second side plate is defined as L2, then:

[0018] 1%≤d1 / L1≤10%;

[0019] 1%≤d2 / L2≤10%.

[0020] In one aspect, 1mm≤d1≤10mm, 1mm≤d2≤10mm.

[0021] In one aspect, the distance between the first side plate and the middle plate is P1, the distance between the second side plate and the middle plate is P2, the winding length of the first winding is S1, and the winding length of the second winding is S2, then:

[0022] 1 / 8≤P1 / S1≤1 / 4;

[0023] 1 / 8≤P2 / S2≤1 / 4.

[0024] In one aspect, 15mm≤P1≤40mm, 15mm≤P2≤40mm.

[0025] In addition, in order to solve the above-mentioned problems, the present application also provides a frequency converter, which includes a rectifier main circuit, an inverter circuit and the DC reactor mentioned above, the first input cable and the second input cable of the DC reactor are connected to the rectifier main circuit, and the first output cable and the second output cable are connected to the inverter circuit.

[0026] The beneficial effects of the present invention are as follows: the first side plate and the second side plate are separated by the middle plate, the first side plate is used to set the first winding, and the second side plate is used to set the second winding. The first side plate, the first winding and the middle plate can suppress harmonics, and the second side plate, the second winding and the middle plate can also suppress harmonics. By setting the middle plate at intervals, the two reactors are integrated together, thereby reducing the structural volume and improving the convenience of assembly. Moreover, the width of the middle plate is smaller than the width of the first side plate, and the effect of further reducing the structural volume is achieved by reducing the width of the middle plate, which is more conducive to assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0028] Figure 1 It is a structural schematic diagram of the DC reactor in this application;

[0029] Figure 2 For this application Figure 1 A schematic structural diagram of an embodiment of a magnetic core in a DC reactor;

[0030] Figure 3 For this application Figure 1 A schematic structural diagram of another embodiment of a magnetic core in a DC reactor;

[0031] Figure 4 A schematic diagram of the DC reactor for reducing differential mode harmonics in this application;

[0032] Figure 5 Schematic diagram of the DC reactor used in the present application to reduce common mode harmonics.

[0033] Reference numerals: 100, first iron yoke; 200, second iron yoke; 300, magnetic core; 400, first winding; 500, second winding; 600, main rectifier circuit; 700, inverter circuit; 800, bracket;

[0034] 310, first side plate; 320, second side plate; 330, middle plate; 301, first air gap; 302, second air gap; 311, first connecting section; 312, second connecting section; 321, third connecting section; 322, fourth connecting section; 410, first incoming cable; 420, first outgoing cable; 430, second incoming cable; 440, second outgoing cable. DETAILED DESCRIPTION

[0035] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0036] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0037] The present application provides a DC reactor, which includes: a first iron yoke 100, a second iron yoke 200, a magnetic core 300, a first winding 400 and a second winding 500. The iron yoke is usually made of silicon steel sheets or other high magnetic permeability materials, and has sufficient mechanical strength to support the weight of the coil. The magnetic core 300 refers to a sintered magnetic metal oxide composed of a mixture of various iron oxides. For example, manganese-zinc ferrite and nickel-zinc ferrite are typical materials for the magnetic core 300. Manganese-zinc ferrite has the characteristics of high magnetic permeability and high magnetic flux density, and has the characteristics of low loss. Nickel-zinc ferrite has extremely high resistivity, low magnetic permeability of less than a few hundred and other characteristics. Ferrite core 300 and the like.

[0038] The first iron yoke 100 and the second iron yoke 200 are arranged opposite to each other; there is a certain distance between the first iron yoke 100 and the second iron yoke 200, and usually the first iron yoke 100 and the second iron yoke 200 are arranged in parallel.

[0039] The magnetic core 300 is arranged between the first iron yoke 100 and the second iron yoke 200. The magnetic core 300 includes a first side plate 310, a second side plate 320 and a middle plate 330. The first side plate 310 and the second side plate 320 are respectively arranged on both sides of the middle plate 330. The first side plate 310 and the second side plate 320 are spaced apart from the middle plate 330. At least one end of the first side plate 310 is connected to the first iron yoke 100 or the second iron yoke 200, that is, one end of the first side plate 310 is connected to the first iron yoke 100, and the other end is spaced apart from the second iron yoke 200, or one end of the first side plate 310 is connected to the second iron yoke 200, and the other end is spaced apart from the first iron yoke 100, or the first side plate 310 is connected to both the first iron yoke 100 and the second iron yoke 200. At least one end of the second side plate 320 is connected to the first iron yoke 100 or the second iron yoke 200. It can also be known that one end of the second side plate 320 is connected to the first iron yoke 100, and the other end is spaced from the second iron yoke 200, or one end of the second side plate 320 is connected to the second iron yoke 200, and the other end is spaced from the first iron yoke 100, or the second side plate 320 is connected to both the first iron yoke 100 and the second iron yoke 200. One end of the middle plate 330 is connected to the first iron yoke 100, and the other end of the middle plate 330 is connected to the second iron yoke 200. The first side plate 310 and the second side plate 320 are distinguished by the middle plate 330. The widths of the first side plate 310 and the second side plate 320 are equal, and the width of the middle plate 330 is smaller than the width of the first side plate 310; by reducing the width of the middle plate 330, the structural volume is reduced.

[0040] The first winding 400 is wound on the first side plate 310 , one end of the first winding 400 is connected to a first input cable 410 , and the other end of the first winding 400 is connected to a first output cable 420 ; the first input cable 410 is used for current to flow into the connection port, and the first output cable 420 is used for current to flow out.

[0041] The second winding 500 is wound on the second side plate 320. The first winding 400 and the second winding 500 are wound in the same direction. One end of the second winding 500 is connected to a second input cable 430, and the other end of the second winding 500 is connected to a second output cable 440. The first input cable 410 and the second input cable 430 are located on the same side of the magnetic core 300. The second input cable 430 is used for current inflow connection, and the second output cable 440 is used for current outflow.

[0042] In the DC reactor of this embodiment, the first side plate 310 and the second side plate 320 are separated by the middle plate 330. The first side plate 310 is used to set the first winding 400, and the second side plate 320 is used to set the second winding 500. The first side plate 310, the first winding 400 and the middle plate 330 can suppress harmonics, and the second side plate 320, the second winding 500 and the middle plate 330 can also suppress harmonics. By setting the middle plate 330 at intervals, the two reactors are integrated together, thereby reducing the structural volume and improving the convenience of assembly. Moreover, the width of the middle plate 330 is smaller than the width of the first side plate 310. By reducing the width of the middle plate 330, the effect of further reducing the structural volume is achieved, which is more conducive to assembly.

[0043] In addition, it should be noted that the first iron yoke 100 and the second iron yoke 200 in the present application may also be plate-shaped structures, and the magnetic core 300 is also a plate-shaped structure as can be seen from the structures of the first side plate 310, the second side plate 320 and the middle plate 330. It can be understood that the DC reactor of the present application is mainly a flat structure, which is thinner overall and is conducive to installation in the inverter.

[0044] The DC reactor further includes a bracket 800 , which is disposed on the first iron yoke 100 and the second iron yoke 200 and is used for fixing the DC reactor.

[0045] In one embodiment of the present application, the width of the middle plate 330 is w, and the width of the first side plate 310 is W1, which satisfies: 20%≤w / W1≤80%. It can be seen that the width of the middle plate 330 is narrower, for example, the width of the middle plate 330 can be 20%, 30%, 40%, 50%, 60%, 70% or 80% of the width of the first side plate 310. The width of the second side plate 320 is W2, and W1 is equal to W2.

[0046] Furthermore, 20 mm ≤ w ≤ 80 mm. The width of the middle plate 330 may be 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm or 80 mm. The width of the middle plate 330 may be adjusted according to the structural space. In the case of effectively spacing the first side plate 310 and the second side plate 320, the greater the current connected, the wider the width of the middle plate 330.

[0047] like Figure 2As shown, in one embodiment of the present application, one end of the first side plate 310 is connected to the first iron yoke 100, and the other end of the first side plate 310 is spaced from the second iron yoke 200 to form a first air gap 301; one end of the second side plate 320 is connected to the first iron yoke 100, and the other end of the second side plate 320 is spaced from the second iron yoke 200 to form a second air gap 302. The air in the air gap of the magnetic core 300 has a greater obstruction effect on the magnetic field, resulting in the obstruction of the magnetic flux at the air gap, thereby reducing the magnetic permeability. The introduction of the air gap makes the magnetic domain arrangement of the magnetic core 300 less orderly, and a larger current is required to make the magnetic core 300 reach a saturation state. When the magnetic field is established in the magnetic core 300, the magnetic domains will be arranged in an orderly state, thereby storing energy. Due to the existence of the air gap, the orderliness of the magnetic domain arrangement is broken, so that the magnetic core 300 can store more energy. The introduction of the air gap can destroy the orderliness of the magnetic domain arrangement, thereby reducing the residual magnetism. Of course, the first air gap 301 and the second air gap 302 may also be arranged at an end close to the first iron yoke 100 .

[0048] like Figure 3 As shown, in one embodiment of the present application, the first side plate 310 includes a first connecting section 311 and a second connecting section 312, one end of the first connecting section 311 is connected to the first iron yoke 100, one end of the second connecting section 312 is connected to the second iron yoke 200, and the first connecting section 311 and the second connecting section 312 are relatively spaced to form a first air gap 301; the second side plate 320 includes a third connecting section 321 and a fourth connecting section 322, one end of the third connecting section 321 is connected to the first iron yoke 100, one end of the fourth connecting section 322 is connected to the second iron yoke 200, and the third connecting section 321 and the fourth connecting section 322 are relatively spaced to form a second air gap 302. The first air gap 301 can be set in the middle of the first side plate 310, and the second air gap 302 can also be set in the middle of the second side plate 320.

[0049] In one embodiment of the present application, the width of the first air gap 301 is defined as d1, the width of the second air gap 302 is defined as d2, the length of the first side plate 310 is defined as L1, and the length of the second side plate 320 is defined as L2, then the following conditions are satisfied: 1%≤d1 / L1≤10%, 1%≤d2 / L2≤10%. The width of the first air gap 301 and the width of the second air gap 302 can also be adjusted as needed. The ratio of the width of the first air gap 301 to the length of the first side plate 310 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%. The ratio of the width of the second air gap 302 to the length of the second side plate 320 can also be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

[0050] Further, 1mm≤d1≤10mm, 1mm≤d2≤10mm. The width of the first air gap 301 can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm or 10mm. The width of the second air gap 302 can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm or 10mm.

[0051] In one embodiment of the present application, the distance between the first side plate 310 and the middle plate 330 is P1, the distance between the second side plate 320 and the middle plate 330 is P2, the winding length of the first winding 400 is S1, and the winding length of the second winding 500 is S2, then the following conditions are satisfied: 1 / 8≤P1 / S1≤1 / 4, 1 / 8≤P2 / S2≤1 / 4. The distance between the first side plate 310 and the middle plate 330 is sufficient to accommodate the first winding 400, and similarly, the distance between the second side plate 320 and the middle plate 330 is sufficient to accommodate the second winding 500. The ratio of P1 to S1 can be 1 / 8, 1 / 7, 1 / 6, 1 / 5 or 1 / 4, and the ratio of P2 to S2 can also be 1 / 8, 1 / 7, 1 / 6, 1 / 5 or 1 / 4. P1 can be equal to P2.

[0052] Further, 15mm≤P1≤40mm, 15mm≤P2≤40mm. P1 can be 15mm, 20mm, 25mm, 30mm, 35mm or 40mm. P2 can also be 15mm, 20mm, 25mm, 30mm, 35mm or 40mm.

[0053] The present application also provides a frequency converter, which includes a rectifier main circuit 600, an inverter circuit 700 and the above DC reactor, wherein the first input cable 410 and the second input cable 430 of the DC reactor are connected to the rectifier main circuit 600, and the first output cable 420 and the second output cable 440 are connected to the inverter circuit 700. The DC reactor reduces harmonics passing through the rectifier main circuit 600. The solution of the present application can reduce common-mode harmonics when common-mode harmonics are generated, and can also reduce differential-mode harmonics when differential-mode harmonics are generated.

[0054] The rectifier main circuit 600 is used to convert three-phase AC power into single-phase DC power, and the inverter circuit 700 corresponds to the rectifier circuit 600 . The inverter circuit 700 converts DC power into AC power.

[0055] like Figure 4As shown, it can be found that the differential mode current signal in the magnetic integrated dual DC reactor at the output end of the rectifier main circuit 600 has a flow path of abdc, and the winding direction of the first winding 400 and the second winding 500 is the same. At this time, the differential mode magnetic flux flows in the closed magnetic circuit formed by the first side plate 310 and the middle plate 330, and the second side plate 320 and the middle plate 330, respectively, to form a differential mode inductor Q1 and a differential mode inductor Q2, and the differential mode magnetic flux cancels each other on the middle plate 330.

[0056] like Figure 5 As shown, the common-mode current signal in the integrated dual DC reactor at the output end of the rectifier main circuit 600 flows in the a`-b` and c`-d` paths, and the winding directions of the first winding 400 and the second winding 500 are the same. At this time, the common-mode magnetic flux flows in the closed magnetic circuit formed by the two side plates 6 and the middle plate 330, respectively, to form common-mode inductance Q1` and common-mode inductance Q2`, and the common-mode inductances also cancel each other out.

[0057] In the frequency converter of this embodiment, the first side plate 310 and the second side plate 320 are separated by the middle plate 330, the first side plate 310 is used to set the first winding 400, and the second side plate 320 is used to set the second winding 500. The first side plate 310, the first winding 400 and the middle plate 330 can suppress harmonics, and the second side plate 320, the second winding 500 and the middle plate 330 can also suppress harmonics. By setting the interval of the middle plate 330, it is equivalent to integrating the two reactors together, thereby reducing the structural volume and improving the convenience of assembly. Moreover, the width of the middle plate 330 is less than the width of the first side plate 310, and the effect of further reducing the structural volume is achieved by reducing the width of the middle plate 330, which is more conducive to assembly. In addition, in the present application, the first iron yoke 100 and the second iron yoke 200 are both plate-like structures. It can be seen from the structures of the first side plate 310, the second side plate 320 and the middle plate 330 that the magnetic core 300 is also a plate-like structure. The DC reactor of the present application is mainly a flat structure, which is thinner as a whole and is convenient for installation in a frequency converter.

[0058] The specific embodiments and beneficial effects of the chip in this application refer to the above-mentioned DC reactor and will not be repeated here.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A DC reactor, characterized in that: The DC reactor comprises: First Iron Yoke; a second iron yoke, wherein the first iron yoke and the second iron yoke are arranged opposite to each other; A magnetic core, wherein the magnetic core is arranged between the first iron yoke and the second iron yoke, the magnetic core comprises a first side plate, a second side plate and a middle plate, the first side plate and the second side plate are arranged on both sides of the middle plate, the first side plate and the second side plate are arranged spaced apart from the middle plate, at least one end of the first side plate is connected to the first iron yoke or the second iron yoke, at least one end of the second side plate is connected to the first iron yoke or the second iron yoke, one end of the middle plate is connected to the first iron yoke, and the other end of the middle plate is connected to the second iron yoke, the first side plate and the second side plate have the same width, and the width of the middle plate is smaller than the width of the first side plate; A first winding, wherein the first winding is wound on the first side plate, one end of the first winding is connected to a first input cable, and the other end of the first winding is connected to a first output cable; The second winding is wound on the second side plate, the first winding and the second winding are wound in the same direction, one end of the second winding is connected to a second input cable, the other end of the second winding is connected to a second output cable, and the first input cable and the second input cable are located on the same side of the magnetic core.

2. The DC reactor according to claim 1, characterized in that: The width of the middle plate is w, and the width of the first side plate is W1, which satisfies: 20%≤w / W1≤80%.

3. The DC reactor according to claim 2, characterized in that: 20mm≤w≤80mm.

4. The DC reactor according to claim 1, characterized in that: One end of the first side plate is connected to the first iron yoke, and a first air gap is formed between the other end of the first side plate and the second iron yoke; One end of the second side plate is connected to the first iron yoke, and a second air gap is formed between the other end of the second side plate and the second iron yoke.

5. The DC reactor according to claim 1, characterized in that: The first side plate includes a first connecting section and a second connecting section, one end of the first connecting section is connected to the first iron yoke, one end of the second connecting section is connected to the second iron yoke, and the first connecting section and the second connecting section are relatively spaced to form a first air gap; The second side plate includes a third connecting segment and a fourth connecting segment, one end of the third connecting segment is connected to the first iron yoke, one end of the fourth connecting segment is connected to the second iron yoke, and the third connecting segment and the fourth connecting segment are relatively spaced to form a second air gap.

6. The DC reactor according to claim 4 or 5, characterized in that: Define the width of the first air gap as d1, the width of the second air gap as d2, the length of the first side plate as L1, and the length of the second side plate as L2, then: 1%≤d1 / L1≤10%; 1%≤d2 / L2≤10%.

7. The DC reactor according to claim 6, characterized in that: 1mm≤d1≤10mm, 1mm≤d2≤10mm.

8. The DC reactor according to claim 1, characterized in that: The distance between the first side plate and the middle plate is P1, the distance between the second side plate and the middle plate is P2, the winding length of the first winding is S1, and the winding length of the second winding is S2, then: 1 / 8≤P1 / S1≤1 / 4; 1 / 8≤P2 / S2≤1 / 4.

9. The DC reactor according to claim 8, characterized in that: 15mm≤P1≤40mm, 15mm≤P2≤40mm.

10. A frequency converter, characterized in that: The frequency converter includes a rectifier main circuit, an inverter circuit, and a DC reactor according to any one of claims 1 to 9, wherein a first input cable and a second input cable of the DC reactor are connected to the rectifier main circuit, and the first output cable and the second output cable are connected to the inverter circuit.

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