Three-phase four-frame type triple-frequency transformer

Abstract

This application relates to a three-phase four-frame type triple-frequency transformer, which includes four sub-frame iron cores, and also includes three primary windings and three secondary windings. The three primary windings are respectively wound around the adjacent core columns of the four sub-frame iron cores, and the three secondary windings are respectively wound on the same side yokes of three adjacent sub-frame iron cores among the four sub-frame iron cores. After the three primary windings are connected, they are connected to the three-phase terminal, and after the three secondary windings are connected, they are connected to the single-phase terminal. The voltage frequency of the single-phase terminal is three times that of the voltage frequency of the three-phase terminal, which avoids the operation of each sub-frame iron core in a highly saturated state, and there is no need to limit the connection method of the primary winding, realizes the triple-frequency voltage output of the secondary winding, and has a small exciting current and higher efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of transformers, and particularly to a three-phase four-frame type triple-frequency transformer. Background Art

[0002] A triple-frequency transformer utilizes the nonlinear and saturation characteristics of ferromagnetic materials and the special connection of windings, so that the transformer generates rich third harmonics, and uses the third harmonics to form a triple-frequency voltage. Ferromagnetic triple-frequency transformers have been widely used in the tests of equipment such as transformers and voltage transformers, and frequency-divided power transmission systems.

[0003] In the prior art, in order to implement a triple-frequency transformer, most are composed of three single-phase transformers with equal magnetic path lengths. The primary windings are star-connected, and the secondary windings are open-delta-connected. There are problems such as large exciting current and low efficiency when the iron core operates in a highly saturated state. Summary of the Invention

[0004] Based on this, in view of the problems of large exciting current and low efficiency of the existing triple-frequency transformer, it is necessary to provide a three-phase four-frame type triple-frequency transformer.

[0005] A three-phase four-frame type triple-frequency transformer includes: an iron core and windings. The iron core includes a first sub-frame iron core, a second sub-frame iron core, a third sub-frame iron core, and a fourth sub-frame iron core. The adjacent parts of the first sub-frame iron core and the second sub-frame iron core are combined into a first core column, the adjacent parts of the second sub-frame iron core and the third sub-frame iron core are combined into a second core column, and the adjacent parts of the third sub-frame iron core and the fourth sub-frame iron core are combined into a third core column;

[0006] The windings include three primary windings and three secondary windings. The three primary windings are respectively wound around the first core column, the second core column, and the third core column. The three secondary windings are respectively wound on the same-side yokes of three adjacent sub-frame iron cores among the first sub-frame iron core, the second sub-frame iron core, the third sub-frame iron core, and the fourth sub-frame iron core. After the three primary windings are connected, they are connected to the three-phase terminals. After the three secondary windings are connected, they are connected to the single-phase terminal. The voltage frequency of the single-phase terminal is three times the voltage frequency of the three-phase terminals.

[0007] In one embodiment, the first sub-frame iron core, the second sub-frame iron core, the third sub-frame iron core, and the fourth sub-frame iron core are all rectangular sub-frame iron cores, and are arranged in a line on the same plane.

[0008] In one embodiment, the first sub-frame iron core, the second sub-frame iron core, the third sub-frame iron core, and the fourth sub-frame iron core have equal areas.

[0009] In one embodiment, equal-distance air gaps are used to separate the adjacent core columns of the first sub-frame core, the second sub-frame core, the third sub-frame core, and the fourth sub-frame core.

[0010] In one embodiment, the first sub-frame core, the second sub-frame core, the third sub-frame core, and the fourth sub-frame core are wound cores or stacked cores.

[0011] In one embodiment, the connection mode of the three primary windings is Y connection, D connection, or YN connection.

[0012] In one embodiment, the three primary windings are wound in the same direction on the iron core.

[0013] In one embodiment, the connection mode of the three secondary windings is open delta connection.

[0014] In one embodiment, the three secondary windings are wound in the same direction on the iron core.

[0015] In one embodiment, it further includes three regulating windings. The three regulating windings are respectively connected to the three secondary windings, and the three regulating windings are wound on the yokes of the sub-frame cores.

[0016] For the above three-phase four-frame type triple-frequency transformer, the iron core includes four sub-frame cores. Three primary windings are wound on the adjacent core columns of each sub-frame core. Three secondary windings are wound on the yokes on the same side of three adjacent sub-frame cores. After the three primary windings are connected, they are connected to the three-phase terminals. After the three secondary windings are connected, they are connected to the single-phase terminals. There is no need to limit the connection mode of the primary windings, which avoids the operation of each sub-frame core in a highly saturated state, realizes the triple-frequency voltage output of the secondary windings, and has a small exciting current and higher efficiency. Description of the Drawings

[0017] Figure 1 It is a structural diagram of a three-phase four-frame type triple-frequency transformer in one embodiment;

[0018] Figure 2 It is a wiring diagram of three primary windings in one embodiment;

[0019] Figure 3 It is a wiring diagram of three primary windings in another embodiment;

[0020] Figure 4 It is a wiring diagram of three primary windings in another embodiment;

[0021] Figure 5 It is a wiring diagram of three secondary windings in one embodiment. Detailed Embodiments

[0022] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0024] It can be understood that the terms "first", "second", etc. used in this application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, the first resistor can be called the second resistor, and similarly, the second resistor can be called the first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0025] It can be understood that in the following embodiments, "connection", if there is an electrical signal or data transfer between the connected circuits, modules, units, etc., should be understood as "electrical connection", "communication connection", etc.

[0026] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising", "including" or "having", etc. specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0027] In one embodiment, as Figure 1As shown in the figure, a three-phase four-frame type triple-frequency transformer is provided, including: an iron core and windings. The iron core includes a first sub-frame iron core 11, a second sub-frame iron core 12, a third sub-frame iron core 13, and a fourth sub-frame iron core 14. The adjacent parts of the first sub-frame iron core 11 and the second sub-frame iron core 12 are combined into a first core column, the adjacent parts of the second sub-frame iron core 12 and the third sub-frame iron core 13 are combined into a second core column, and the adjacent parts of the third sub-frame iron core 13 and the fourth sub-frame iron core 14 are combined into a third core column. The windings include three primary windings (21, 22, 23) and three secondary windings (31, 32, 33). The three primary windings (21, 22, 23) are respectively wound around the first core column, the second core column, and the third core column. The three secondary windings (31, 32, 33) are respectively wound on the same-side yokes of three adjacent sub-frame iron cores among the first sub-frame iron core 11, the second sub-frame iron core 12, the third sub-frame iron core 13, and the fourth sub-frame iron core 14. After the three primary windings (21, 22, 23) are connected, they are connected to the three-phase terminals. After the three secondary windings (31, 32, 33) are connected, they are connected to the single-phase terminal. The voltage frequency of the single-phase terminal is three times that of the three-phase terminal.

[0028] Specifically, the first sub-frame iron core 11, the second sub-frame iron core 12, the third sub-frame iron core 13, and the fourth sub-frame iron core 14 are four quadrilateral sub-frame iron cores, each including upper and lower yokes and left and right columns. Optionally, the sub-frame iron cores are arranged adjacent to each other through the column sides or through the yoke sides. In this embodiment, taking the case where the sub-frame iron cores are arranged adjacent to each other through the column sides as an example for explanation, the two adjacent columns of the first sub-frame iron core 11 and the second sub-frame iron core 12 are combined into a first core column, the two adjacent columns of the second sub-frame iron core 12 and the third sub-frame iron core 13 are combined into a second core column, and the two adjacent columns of the third sub-frame iron core 13 and the fourth sub-frame iron core 14 are combined into a third core column. Among them, the sizes of the sub-frame iron cores need to be kept consistent, including the width and cross-sectional area of the yokes being the same, and the length and cross-sectional area of the columns being the same. Optionally, the width of the yoke of each sub-frame iron core can be equal to the length of the column of each sub-frame iron core, the width of the yoke of each sub-frame iron core can also be less than the length of the column of each sub-frame iron core, and the width of the yoke of each sub-frame iron core can also be greater than the length of the column of each sub-frame iron core, which is not limited thereto.

[0029] Further, the winding includes three primary windings connected to the three-phase terminals and three secondary windings connected to the single-phase terminals. Among them, the three-phase terminals connected by the three primary windings can be used as either the power input terminals or the power output terminals. Correspondingly, the single-phase terminals connected by the three secondary windings can also be used as either the power input terminals or the power output terminals. It can be understood that when the turns ratio of the three primary windings to the three secondary windings is fixed, the triple-frequency transformer of the present application can be used as a step-down transformer or a step-up transformer. Specifically, the three primary windings include the primary winding 21 of phase A, the primary winding 22 of phase B, and the primary winding 23 of phase C, and the three secondary windings include the secondary winding 31 of phase a, the secondary winding 32 of phase b, and the secondary winding 33 of phase c.

[0030] Among them, the three primary windings are respectively wound around the first core column, the second core column, and the third core column. The primary winding 21 of phase A is wound around the first core column, the primary winding 22 of phase B is wound around the second core column, and the primary winding 23 of phase C is wound around the third core column. The primary winding 21 of phase A, the primary winding 22 of phase B, and the primary winding 23 of phase C have the same winding direction and are connected to the three-phase terminals with the same phase and the same polarity. For example, it is assumed that the positive direction of the magnetic flux in each core column around which each primary winding is wound is from bottom to top, and the positive direction of the magnetic flux flowing through each sub-frame core is counterclockwise. It can be understood that since the three input phases of the three-phase power supply differ by 120°, the three-phase fundamental waves in each sub-frame core can be cancelled out. In addition, the number of turns of the primary winding 21 of phase A, the primary winding 22 of phase B, and the primary winding 23 of phase C is the same, and the materials used are also the same. Optionally, the material can be copper foil or electromagnetic wire, etc., and this is not limited.

[0031] In addition, the three secondary windings are respectively wound on the same-side cross yokes of three adjacent sub-frame cores among the first sub-frame core 11, the second sub-frame core 12, the third sub-frame core 13 and the fourth sub-frame core 14. It can be wound on the same-side cross yokes of the first sub-frame core 11, the second sub-frame core 12 and the third sub-frame core 13, or it can be wound on the same-side cross yokes of the second sub-frame core 12, the third sub-frame core 13 and the fourth sub-frame core 14. It can be the upper cross yoke on the same side or the lower cross yoke on the same side. In this embodiment, taking the example of being wound on the upper cross yoke on the same side of the first sub-frame core 11, the second sub-frame core 12 and the third sub-frame core 13 for explanation, the a-phase secondary winding 31 is wound on the upper cross yoke of the first sub-frame core 11, the b-phase secondary winding 32 is wound on the upper cross yoke of the second sub-frame core 12, and the c-phase secondary winding 33 is wound on the upper cross yoke of the third sub-frame core 13. Similarly, the a-phase secondary winding 31, the b-phase secondary winding 32 and the c-phase secondary winding 33 also have the same winding direction, and after being connected in series or in parallel with the same phase and the same polarity, they can be connected to the single-phase terminal. And at this time, due to the cancellation of the three-phase fundamental waves in each sub-frame core, the voltage frequency at the single-phase terminal is three times the voltage frequency at the three-phase terminal, that is, the voltage frequency of the secondary winding is three times the voltage frequency of the primary winding. In addition, the number of turns of the a-phase secondary winding 31, the b-phase secondary winding 32 and the c-phase secondary winding 33 is the same, and the materials used are also the same. Optionally, the material can be copper foil or electromagnetic wire, etc., and this is not limited.

[0032] The following takes Figure 1 the structure diagram of the three-phase four-frame type triple-frequency transformer shown as an example to explain its working principle. Assuming the magnetic fluxes passing through the A-phase primary winding 21, the B-phase primary winding 22 and the C-phase primary winding 23, which can be understood as the synthetic magnetic fluxes passing through two adjacent sub-frame cores, are respectively φ A (t), φ B (t) and φ C (t), and their directions are assumed as shown in the marked directions in Figure 2 ; the magnetic fluxes passing through the a-phase secondary winding 31, the b-phase secondary winding 32 and the c-phase secondary winding 33, which can be understood as the magnetic fluxes passing through each sub-frame core, are respectively φ a (t), φ b (t) and φ c (t), and their directions are assumed as shown in the marked directions in Figure 2 , then according to Kirchhoff's law of magnetic circuits, we can get:

[0033]

[0034] Due to the non-linear characteristics of the ferromagnetic materials used in each sub-frame core, the magnetic flux φ passing through each sub-frame corea (t), φ b (t) and φ c (t), in addition to containing the fundamental component, also contains zero-sequence odd harmonics such as 3, 9, 15..., and mainly the 3rd harmonic, and other higher harmonics can be ignored. Then, assuming the magnetic flux φ a (t), φ b (t) and φ c (t) are respectively:

[0035] φ a (t) = φ m sin(ωt) + kφ m sin(3ωt + θ) (2)

[0036]

[0037]

[0038] Among them, φ m is the amplitude of the fundamental magnetic flux in the magnetic flux φ a (t), φ b (t) and φ c (t) passing through each sub-frame iron core, ω is the angular frequency, and θ is the initial phase angle; in addition, k is the content rate of the 3rd harmonic in the magnetic flux φ a (t), φ b (t) and φ c (t) passing through each sub-frame iron core.

[0039] Then, since the three secondary windings are connected in an open delta connection, the induced voltage u 2 at both ends is equal to the derivative of the sum of the magnetic fluxes passing through the a-phase secondary winding 31, the b-phase secondary winding 32, and the c-phase secondary winding 33, that is, according to equations (2), (3), and (4), it can be obtained:

[0040]

[0041] In the formula, n 2 is the number of turns of the a-phase secondary winding 31, the b-phase secondary winding 32, and the c-phase secondary winding 33.

[0042] Then, since the fundamental waves of the three phases in each sub-frame iron core can cancel each other out, it can be obtained:

[0043] u 2 = 3kφ m n 2 sin(3ωt + θ) / dt (6)

[0044] Taking the derivative of equation (6) gives:

[0045] u 2 = 9kφ m n 2 cos(3ωt + θ) (7)

[0046] As can be seen from Equation (7), the induced voltage u 2 across the two ends of the three secondary windings has a frequency three times that of the voltage across the primary winding, realizing a triple-frequency transformer.

[0047] For the above-mentioned three-phase four-frame triple-frequency transformer, the iron core includes four sub-frame iron cores. Three primary windings are wound around the adjacent core columns of each sub-frame iron core, and three secondary windings are wound around the cross yokes on the same side of three adjacent sub-frame iron cores. After the three primary windings are connected, they are connected to the three-phase terminals, and after the three secondary windings are connected, they are connected to the single-phase terminals. There is no need to limit the connection method of the primary windings, avoiding the operation of each sub-frame iron core in a highly saturated state, realizing the triple-frequency voltage output of the secondary winding, and having a small exciting current and higher efficiency.

[0048] In one embodiment, as Figure 1 shown, the first sub-frame iron core 11, the second sub-frame iron core 12, the third sub-frame iron core 13, and the fourth sub-frame iron core 14 are all rectangular sub-frame iron cores, arranged in a line on the same plane.

[0049] Specifically, the widths of the cross yokes of the first sub-frame iron core 11, the second sub-frame iron core 12, the third sub-frame iron core 13, and the fourth sub-frame iron core 14 are all greater than the lengths of their columns, and the angles between the cross yokes and their columns of the first sub-frame iron core 11, the second sub-frame iron core 12, the third sub-frame iron core 13, and the fourth sub-frame iron core 14 are all right angles, that is, the first sub-frame iron core 11, the second sub-frame iron core 12, the third sub-frame iron core 13, and the fourth sub-frame iron core 14 are all rectangular sub-frame iron cores. Each rectangular sub-frame iron core is spliced together through its column sides and arranged in a line on the same plane.

[0050] In one embodiment, as Figure 1 shown, the areas of the first sub-frame iron core 11, the second sub-frame iron core 12, the third sub-frame iron core 13, and the fourth sub-frame iron core 14 are equal. Specifically, since the widths of the upper and lower cross yokes of the first sub-frame iron core 11, the second sub-frame iron core 12, the third sub-frame iron core 13, and the fourth sub-frame iron core 14 are all equal, and the lengths of the left and right columns of the first sub-frame iron core 11, the second sub-frame iron core 12, the third sub-frame iron core 13, and the fourth sub-frame iron core 14 are also all equal, the areas enclosed by the upper and lower cross yokes and the left and right columns of the first sub-frame iron core 11, the second sub-frame iron core 12, the third sub-frame iron core 13, and the fourth sub-frame iron core 14 are all equal.

[0051] In this embodiment, each sub-frame iron core can avoid continuous operation in a highly saturated state during operation, improving the efficiency of the triple-frequency transformer.

[0052] In one embodiment, as Figure 1 shown, the first sub-frame core 11, the second sub-frame core 12, the third sub-frame core 13 and the fourth sub-frame core 14 are wound cores or stacked cores. Specifically, each sub-frame core can be formed by winding a core strip with a core winding machine and then undergoing annealing treatment, or can be formed by stacking a plurality of core sheets and then making each core sheet seamlessly fit tightly through a clamping device. Among them, different materials can be selected for the core strip and the core sheets, and they can be magnetic materials such as ferrite, amorphous alloy, ultra-thin silicon steel or nanocrystalline. In this embodiment, the sub-frame cores made of non-linear ferromagnetic materials can generate rich zero-sequence harmonic magnetic fluxes between the sub-frames.

[0053] In one embodiment, as Figure 1 shown, the adjacent core columns of the first sub-frame core 11, the second sub-frame core 12, the third sub-frame core 13 and the fourth sub-frame core 14 are separated by equal-distance air gaps. Specifically, an equal-distance air gap is used to separate between the left column of the first sub-frame core 11 and the right column of the second sub-frame core 12, between the left column of the second sub-frame core 12 and the right column of the third sub-frame core 13, and between the left column of the third sub-frame core 13 and the right column of the fourth sub-frame core 14. That is to say, it can be understood that the first core column, the second core column and the third core column all have equal-distance air gaps. Since the magnetic resistance of the air gap is much larger than that of the core sheet, when the air gap is greater than 2 mm, it can be considered that the magnetic circuit between adjacent sub-frame cores is in an open state. Therefore, the air gap size between the adjacent core columns of the first sub-frame core 11, the second sub-frame core 12, the third sub-frame core 13 and the fourth sub-frame core 14 is greater than 2 mm. For example, an air gap size of 6 mm can be adopted. In this embodiment, equal-distance air gaps are used to separate between the core columns of each sub-frame core, so that the magnetic fluxes of each sub-frame core are independent of each other on the premise of maintaining the magnetic circuit symmetry of each sub-frame core.

[0054] In one embodiment, as Figure 2 , Figure 3 and Figure 4 shown, the connection mode of the three primary windings (21, 22, 23) is Y connection, D connection or YN connection.

[0055] Specifically, the connection form of the three primary windings is not unique. Y connection can be adopted, D connection can also be adopted, and YN connection can also be adopted. Among them, in the three connection modes, the heads of the A-phase primary winding 21, the B-phase primary winding 22 and the C-phase primary winding 23 are all used to connect to the three-phase power grid end.

[0056] Furthermore, as Figure 2 shown, the three primary windings adopt the Y-type connection form, and the tails of the A-phase primary winding 21, the B-phase primary winding 22 and the C-phase primary winding 23 are connected at one point. As Figure 3As shown, the three primary windings are connected in a D-type connection form. The A-phase primary winding 21, the B-phase primary winding 22, and the C-phase primary winding 23 are also connected by connecting the head and tail ends. The head end of the A-phase primary winding 21 is connected to the tail end of the B-phase primary winding 22, the head end of the B-phase primary winding 22 is connected to the tail end of the C-phase primary winding 23, and the head end of the C-phase primary winding 23 is connected to the tail end of the A-phase primary winding 21. As Figure 4 As shown, the three primary windings are connected in a YN-type connection form. After the tail ends of the A-phase primary winding 21, the B-phase primary winding 22, and the C-phase primary winding 23 are connected at a point, it is also grounded through this point.

[0057] In this embodiment, the problem of the single connection form of the primary windings of the existing ferromagnetic triple-frequency transformer is solved.

[0058] In one embodiment, as Figure 2 、 Figure 3 and Figure 4 shown, the three primary windings (21, 22, 23) are wound in the same direction around the iron core.

[0059] Specifically, when energized, there is a phase difference between the electromotive force phasors of the winding coils, thereby generating magnetic flux in the iron core. Therefore, the A-phase primary winding 21, the B-phase primary winding 22, and the C-phase primary winding 23 are wound around the iron core in the same winding direction, and as Figure 2 、 Figure 3 and Figure 4 marked by dots in, the three-phase electricity is input from the head ends of the A-phase primary winding 21, the B-phase primary winding 22, and the C-phase primary winding 23, that is, the head ends of the A-phase primary winding 21, the B-phase primary winding 22, and the C-phase primary winding 23 are all the endpoints with positive electromotive force, that is, the same-name ends. In this embodiment, through the same winding direction and the setting of the same-name ends, and the phase difference of the three-phase power supply is 120°, the three-phase fundamental waves in each sub-frame iron core can be cancelled.

[0060] In one embodiment, as Figure 5 shown, the connection method of the three secondary windings (31, 32, 33) is an open delta connection. Specifically, the output ends of the three secondary windings are used as single-phase ends. The head end of the a-phase secondary winding 31 is used as one end of the single-phase end. The tail end of the a-phase secondary winding 31 is connected to the head end of the b-phase secondary winding 32. The tail end of the b-phase secondary winding 32 is connected to the head end of the c-phase secondary winding 33. The tail end of the c-phase secondary winding 33 is used as the other end of the single-phase end.

[0061] In one embodiment, as Figure 5As shown, the three secondary windings (31, 32, 33) are wound in the same direction around the iron core. Specifically, the secondary winding 31 of phase a, the secondary winding 32 of phase b, and the secondary winding 33 of phase c are wound around the sub-frame iron core in the same winding direction, and as Figure 5 In Figure 5 , the dots mark the ends where the electromotive forces of the secondary winding 31 of phase a, the secondary winding 32 of phase b, and the secondary winding 33 of phase c are positive, that is, the corresponding ends. In this embodiment, through the same winding direction and the setting of the corresponding ends, and with a 120° phase difference between the three-phase power supplies, the three-phase fundamental waves in each sub-frame iron core can be cancelled out.

[0062] In one embodiment, the above three-phase four-frame type triple-frequency transformer further includes three voltage regulating windings, which are respectively connected to the three secondary windings and wound around the cross yokes of each sub-frame iron core.

[0063] Specifically, the three voltage regulating windings are respectively connected in series with one secondary winding to change the number of turns of the secondary side winding of the triple-frequency transformer. Among them, when the voltage regulating winding and the secondary winding are wound in the same polarity and direction, it can increase the number of turns of the secondary side winding, and when the voltage regulating winding and the secondary winding are wound in the opposite direction, it can reduce the number of turns of the secondary side winding.

[0064] Furthermore, the three voltage regulating windings are wound around the cross yokes of the sub-frame iron cores where the three secondary windings are wound. They can be all wound around the upper cross yoke or the lower cross yoke on the same side of each sub-frame iron core, or can be respectively wound around the upper cross yoke or the lower cross yoke on different sides of each sub-frame iron core. It can be understood that the voltage regulating winding can also be concentrically laid with the secondary winding on the same cross yoke, and this is not limited thereto.

[0065] In this embodiment, by adding the voltage regulating windings, the magnetic fluxes in the upper and lower cross yokes of the triple-frequency transformer of the present application are symmetrically increased or decreased, so as to produce the effect of adjustable secondary output voltage.

[0066] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0067] The above-described embodiments only represent several implementation manners of the present application. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A three-phase four-frame type triple-frequency transformer, characterized in that, it includes: A core and windings, the core includes a first sub-frame core, a second sub-frame core, a third sub-frame core and a fourth sub-frame core. Where the adjacent parts of the first sub-frame core and the second sub-frame core are combined into a first core column, the adjacent parts of the second sub-frame core and the third sub-frame core are combined into a second core column, the adjacent parts of the third sub-frame core and the fourth sub-frame core are combined into a third core column, and the adjacent core columns of the first sub-frame core, the second sub-frame core, the third sub-frame core and the fourth sub-frame core are separated by equidistant air gaps; The windings include three primary windings and three secondary windings. The three primary windings are respectively wound around the first core column, the second core column and the third core column. The three secondary windings are respectively wound on the same side yoke of three adjacent sub-frame cores among the first sub-frame core, the second sub-frame core, the third sub-frame core and the fourth sub-frame core. After the three primary windings are connected, they are connected to the three-phase terminal. The connection method of the three primary windings is D connection or YN connection. The three secondary windings are connected by an open delta connection method and then connected to the single-phase terminal. The voltage frequency of the single-phase terminal is three times the voltage frequency of the three-phase terminal.

2. The three-phase four-frame type triple-frequency transformer according to claim 1, characterized in that, The first sub-frame core, the second sub-frame core, the third sub-frame core and the fourth sub-frame core are all rectangular sub-frame cores and are arranged in a straight line on the same plane.

3. The three-phase four-frame type triple-frequency transformer according to claim 2, characterized in that, The first sub-frame core, the second sub-frame core, the third sub-frame core and the fourth sub-frame core have equal areas.

4. The three-phase four-frame type triple-frequency transformer according to claim 1, characterized in that, The air gap between the adjacent core columns of the first sub-frame core, the second sub-frame core, the third sub-frame core and the fourth sub-frame core is greater than 2 mm.

5. The three-phase four-frame type triple-frequency transformer according to claim 4, characterized in that, The air gap between the adjacent core columns of the first sub-frame core, the second sub-frame core, the third sub-frame core and the fourth sub-frame core is 6 mm.

6. The three-phase four-frame type triple-frequency transformer according to claim 4, characterized in that, The first sub-frame core, the second sub-frame core, the third sub-frame core and the fourth sub-frame core are wound cores or stacked cores.

7. The three-phase four-frame type triple-frequency transformer according to claim 1, characterized in that, The winding directions of the three primary windings on the core are the same.

8. The three-phase four-frame type triple-frequency transformer according to claim 1, characterized in that, The first sub-frame core, the second sub-frame core, the third sub-frame core and the fourth sub-frame core are made of non-linear ferromagnetic materials.

9. The three-phase four-frame type triple-frequency transformer according to claim 8, characterized in that, The winding directions of the three secondary windings on the core are the same.

10. The three-phase four-frame type triple-frequency transformer according to any one of claims 1-9, characterized in that, it further comprises three voltage regulating windings, the three voltage regulating windings are respectively connected to the three secondary windings, and the three voltage regulating windings are wound on the cross yoke of the sub-frame iron core.

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