Three-frame split type tripler transformer

Abstract

The application relates to a three-frame split type triple-frequency transformer, which comprises a first split-frame core, a second split-frame core and a third split-frame core; further comprises six primary windings and six secondary windings, the primary windings and the secondary windings are two by two into a group and concentrically wound on the opposite columns of the first split-frame core, the second split-frame core and the third split-frame core respectively, the six primary windings are connected to a three-phase terminal after being connected, the six secondary windings are connected to a single-phase terminal after being connected, the voltage frequency of the single-phase terminal is three times that of the three-phase terminal, the connection mode of the primary windings is not limited, the split-frame cores are prevented from working in a highly saturated state, triple-frequency voltage output of the secondary windings is realized, the excitation current is small, and the efficiency is higher.

Description

Technical Field

[0001] The present application relates to the technical field of transformers, and in particular to a three-frame split-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 to generate rich third harmonics, which are then used to generate a triple-frequency voltage. Ferromagnetic triple-frequency transformers are widely used in testing equipment such as transformers and voltage transformers, and in frequency-dividing power transmission systems.

[0003] In order to realize a triple frequency transformer in the existing technology, most of them use three single-phase transformers with equal magnetic path lengths. The primary winding is connected in a star shape and the secondary winding is connected in an open triangle shape. The iron core operates in a highly saturated state, resulting in problems such as large excitation current and low efficiency. Summary of the Invention

[0004] Based on this, it is necessary to provide a three-frame split triple frequency transformer to address the problems of large excitation current and low efficiency of existing triple frequency transformers.

[0005] A three-frame split-type triple-frequency transformer comprises: an iron core and windings; the iron core comprises a first sub-frame iron core, a second sub-frame iron core, and a third sub-frame iron core; the windings comprise six primary windings and six secondary windings, the primary windings and the secondary windings being grouped in pairs and concentrically wound on opposite columns of the first sub-frame iron core, the second sub-frame iron core, and the third sub-frame iron core, the six primary windings being connected to a three-phase terminal, the six secondary windings being connected to a single-phase terminal, the frequency of the voltage at the single-phase terminal being three times the frequency of the voltage at the three-phase terminal.

[0006] In one embodiment, the first frame core, the second frame core, and the third frame core are all rectangular frame cores with equal areas.

[0007] In one embodiment, the first frame core, the second frame core, and the third frame core are wound cores or laminated cores.

[0008] In one embodiment, the first split iron core, the second split iron core, and the third split iron core are disposed in the same oil tank or are respectively disposed in three independent oil tanks.

[0009] In one embodiment, the six secondary windings are arranged outside the six primary windings.

[0010] In one embodiment, the six primary windings are connected in series in pairs with opposite polarities into three groups, and then connected in a Y connection, a D connection or a YN connection.

[0011] In one embodiment, the six primary windings are wound in the same direction on the core.

[0012] In one embodiment, the six secondary windings of the same polarity are connected in parallel in pairs and then connected in an open delta connection manner.

[0013] In one embodiment, the six secondary windings are wound in the same direction on the core.

[0014] In one embodiment, six voltage regulating windings are further included, and the six voltage regulating windings are respectively connected to the six secondary windings. The six voltage regulating windings are also concentrically wound on the left and right columns of the first sub-frame iron core, the second sub-frame iron core and the third sub-frame iron core.

[0015] The above-mentioned three-frame split-type triple-frequency transformer has an iron core including three sub-frame iron cores. Six primary windings and six secondary windings are concentrically wound on the opposite columns of the three sub-frame iron cores in groups of two. The six primary windings are connected to the three-phase terminal after being connected, and the six secondary windings are connected to the single-phase terminal after being connected. There is no need to limit the connection method of the primary winding, which avoids the sub-frame iron cores from working in a highly saturated state, realizing the triple-frequency voltage output of the secondary winding, and the excitation current is small and the efficiency is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural diagram of a three-frame split-type triple frequency transformer in one embodiment;

[0017] Figure 2 This is a wiring diagram of six primary windings in one embodiment;

[0018] Figure 3 is a wiring diagram of six primary windings in another embodiment;

[0019] Figure 4 is a wiring diagram of six primary windings in another embodiment;

[0020] Figure 5 FIG. 4 is a wiring diagram of six secondary windings in one embodiment. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0023] It will be understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor without departing from the scope of this application. The first resistor and the second resistor are both resistors, but they are not the same resistor.

[0024] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if there is transmission of electrical signals or data between the connected circuits, modules, units, etc.

[0025] When used herein, the singular forms "a", "an", and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0026] In one embodiment, Figure 1 As shown, a three-frame split-type triple-frequency transformer is provided, which is applied to the testing of equipment such as transformers and voltage transformers and scenarios such as frequency-divided power transmission systems, including: an iron core and a winding; the iron core includes a first sub-frame iron core 11, a second sub-frame iron core 12 and a third sub-frame iron core 13; the winding includes six primary windings (21, 22, 23, 24, 25, 26) and six secondary windings (31, 32, 33, 34, 35, 36), and the primary windings and the secondary windings are concentrically wound on the columns opposite to the first sub-frame iron core 11, the second sub-frame iron core 12 and the third sub-frame iron core 13 in pairs. The six primary windings (21, 22, 23, 24, 25, 26) are connected to the three-phase terminal, and the six secondary windings (31, 32, 33, 34, 35, 36) are connected to the single-phase terminal, and the voltage frequency of the single-phase terminal is three times the voltage frequency of the three-phase terminal.

[0027] Specifically, the core includes a first sub-frame core 11, a second sub-frame core 12, and a third sub-frame core 13. The first sub-frame core 11, the second sub-frame core 12, and the third sub-frame core are three quadrilateral sub-frame cores surrounded by upper and lower cross yokes and left and right columns. The dimensions of each sub-frame core must be consistent, including the width and cross-sectional area of ​​the cross yokes are the same, and the length and cross-sectional area of ​​the columns are also the same. Optionally, the width of the cross yoke of each sub-frame core can be equal to the length of the columns of each sub-frame core, the width of the cross yoke of each sub-frame core can also be less than the length of the columns of each sub-frame core, and the width of the cross yoke of each sub-frame core can also be greater than the length of the columns of each sub-frame core, without being limited to this.

[0028] Furthermore, the winding includes six primary windings connected to the three-phase grid end and six secondary windings connected to the single-phase end, wherein the three-phase end connected to the six primary windings can be used as both a power input end and a power output end, and correspondingly, the single-phase end connected to the six secondary windings can also be used as both a power input end and a power output end. It can be understood that when the turn ratio of the six primary windings and the six secondary windings is fixed, the triple frequency transformer of the present application can be used as a step-down transformer or as a step-up transformer. Specifically, the six primary windings include a primary winding 21 and a primary winding 22 wound on the first sub-frame iron core, a primary winding 23 and a primary winding 24 wound on the second sub-frame iron core, and a primary winding 25 and a primary winding 26 wound on the third sub-frame iron core. The six secondary windings include a secondary winding 31 and a secondary winding 32 wound on the first sub-frame iron core, a secondary winding 33 and a secondary winding 34 wound on the second sub-frame iron core, and a secondary winding 35 and a secondary winding 36 wound on the third sub-frame iron core.

[0029] Among them, the primary winding 21 is wound on the left column of the first sub-frame core, the primary winding 22 is wound on the right column of the first sub-frame core, the primary winding 23 is wound on the left column of the second sub-frame core, the primary winding 24 is wound on the right column of the second sub-frame core, the primary winding 25 is wound on the left column of the third sub-frame core, and the primary winding 26 is wound on the right column of the third sub-frame core. In addition, each primary winding has the same number of turns around the sub-frame core and uses the same material. Optionally, the material can be copper foil or electromagnetic wire, etc., without limitation.

[0030] In addition, each secondary winding is concentrically wound with the primary winding on a column of the same sub-frame core. Optionally, the secondary winding may be wound overlappingly on the outside of the primary winding, the primary winding may be wound overlappingly on the outside of the secondary winding, or the primary winding may be wound concentrically on the upper and lower columns of the same sub-frame core without overlapping. Optionally, in other embodiments, insulating paper, insulating oil, or epoxy resin may be used to achieve electrical isolation between the primary winding and this winding. The following explanation is given by taking the example of the secondary winding being concentrically wound on the outside of the primary winding. The secondary winding 31 is concentrically wound on the outside of the primary winding 21 on the left column of the first sub-frame core, the secondary winding 32 is concentrically wound on the outside of the primary winding 22 on the right column of the first sub-frame core, the secondary winding 33 is concentrically wound on the outside of the primary winding 23 on the left column of the second sub-frame core, the secondary winding 34 is concentrically wound on the outside of the primary winding 24 on the right column of the second sub-frame core, the secondary winding 35 is concentrically wound on the outside of the primary winding 25 on the left column of the third sub-frame core, and the secondary winding 36 is concentrically wound on the outside of the primary winding 26 on the right column of the third sub-frame core. In addition, each secondary winding has the same number of turns wound on the sub-frame core and uses the same material. Optionally, the material can be copper foil or electromagnetic wire, etc., without limitation.

[0031] The following Figure 1 The working principle of the three-frame split-type triple-frequency transformer is explained using the structural diagram as an example. Assume that the primary winding is wound on the columns of each sub-frame core and the secondary winding is wound on the outside of the primary winding. Assume that the primary winding 21 wound on the column of the first sub-frame core is HVA1, the primary winding 22 is HVA2, the secondary winding 31 is LVA1, and the secondary winding 32 is LVA2; the primary winding 23 wound on the column of the second sub-frame core is HVB1, the primary winding 24 is HVB2, the secondary winding 33 is LVB1, and the secondary winding 34 is LVB2; the primary winding 25 wound on the column of the third sub-frame core is HVC1, the primary winding 26 is HVC2, the secondary winding 35 is LVC1, and the secondary winding 36 is LVC2. Let the induced voltage generated by the primary winding HVA1 and the primary winding HVA2 be u HVA , let the induced voltage generated by the primary winding HVB1 and the primary winding HVB2 be u HVB , the induced voltage generated by the primary winding HVC1 and the primary winding HVC2 is set to u HVC Similarly, let the induced voltage generated by the secondary winding LVA1 and the secondary winding LVA2 be u LVA , let the induced voltage generated by the secondary winding LVB1 and the secondary winding LVB2 be u LVB , let the induced voltage generated by the secondary winding LVC1 and the secondary winding LVC2 be u LVC .

[0032] Assuming that the primary winding is connected in YN mode, the voltage u between the first end of the primary winding and the ground is SA 、u SB and u SC They are:

[0033]

[0034] According to formula (1), divided by the number of turns n1 of the primary winding, the equation still exists, then:

[0035]

[0036] Among them, u HVA / n1、u HVB / n1、u HVC / n1 are the induced voltages of the magnetic flux passing through the three frame cores. In the linear system, u HVA / n1、u HVB / n1、u HVC / n1 only contains three-phase fundamental components, but the ferromagnetic materials used in the iron cores of each frame have nonlinear characteristics, u HVA / n1、u HVB / n1、u HVC / n1 also contains zero-sequence odd harmonic components such as 3, 9, 15, etc., and the third harmonic component is the main one, and other high-order harmonics can be ignored. Assuming that the magnetic flux φ passing through the core of each frame is a (t),φ b (t) and φ c (t) are:

[0037] φ a (t) = φ m sin(ωt)+kφ m sin(3ωt+θ) (3)

[0038]

[0039]

[0040] Among them, φ m is the magnetic flux φ passing through each frame core a (t),φ b (t) and φ c (t) is the amplitude of the fundamental magnetic flux, ω is the angular frequency, θ is the initial phase angle; in addition, k is the magnetic flux φ passing through the core of each frame a (t),φ b (t) and φ c (t) The content ratio of the third harmonic.

[0041] Then, since the secondary winding adopts an open triangle connection method, the induced voltage u2 output by the single-phase power supply terminal connected to the six secondary windings is equal to the derivative of the sum of the flux linkages passing through the six secondary windings, that is, according to equations (3), (4) and (5), we can get:

[0042]

[0043] Where n2 is the number of turns of the six secondary windings.

[0044] Then, since the fundamental waves of the three phases in the iron cores of each frame can cancel each other, we can get:

[0045] u2=3kφ m n2dsin(3ωt+θ) / dt (7)

[0046] By taking the derivative of formula (7), we can get:

[0047] u2=9kφ m n2cos(3ωt+θ) (8)

[0048] It can be seen from formula (8) that the frequency of the induced voltage u2 at both ends of the six secondary windings is three times the frequency of the voltage at both ends of the primary winding, realizing a triple frequency transformer.

[0049] The above-mentioned three-frame split-type triple-frequency transformer has an iron core including three sub-frame iron cores. Six primary windings and six secondary windings are concentrically wound on the opposite columns of the three sub-frame iron cores in groups of two. The six primary windings are connected to the three-phase terminal after being connected, and the six secondary windings are connected to the single-phase terminal after being connected. There is no need to limit the connection method of the primary winding, which avoids the sub-frame iron cores from working in a highly saturated state, realizing the triple-frequency voltage output of the secondary winding, and the excitation current is small and the efficiency is higher.

[0050] In one embodiment, Figure 1 As shown, the first frame core 11 , the second frame core 12 and the third frame core 13 are all rectangular frame cores with equal areas.

[0051] Specifically, the widths of the transverse yokes of the first, second, and third frame cores 11, 12, and 13 are all greater than the lengths of their columns, and the angles between the transverse yokes and their columns of the first, second, and third frame cores 11, 12, and 13 are all right angles, that is, the first, second, and third frame cores 11, 12, and 13 are all rectangular frame cores.

[0052] Furthermore, since the widths of the upper and lower transverse yokes of the first frame core 11, the second frame core 12, and the third frame core 13 are equal, and the lengths of the left and right columns of the first frame core 11, the second frame core 12, and the third frame core 13 are also equal, the areas enclosed by the upper and lower transverse yokes and the left and right columns of the first frame core 11, the second frame core 12, and the third frame core 13 are equal.

[0053] In this embodiment, each frame core does not continuously operate in a high saturation state during operation, thereby improving the efficiency of the triple frequency transformer.

[0054] In one embodiment, Figure 1 As shown, the first frame core 11 , the second frame core 12 and the third frame core 13 are wound cores or laminated cores.

[0055] Specifically, each core frame can be formed by winding a core strip on a core winding machine and then annealing it, or by stacking multiple core sheets and seamlessly joining them together using a clamping device. The core strip and sheets can be made of various materials, including ferrite, amorphous alloys, ultra-thin silicon steel, or nanocrystalline magnetic materials. In this embodiment, the core frame is made of nonlinear ferromagnetic material, which allows for the generation of rich zero-sequence harmonic magnetic flux between the frames.

[0056] In one embodiment, Figure 1 As shown, the first, second, and third split cores 11, 12, and 13 are housed in the same oil tank or in three separate oil tanks. Specifically, since the three split cores are connected only by wiring between the windings, they can be stored in insulating oil for cooling and insulation. They can be housed in the same oil tank to save space, or they can be housed in three separate oil tanks to reduce the size of a single-phase product.

[0057] In one embodiment, Figure 1 As shown, the six secondary windings (31, 32, 33, 34, 35, 36) are arranged outside the six primary windings (21, 22, 23, 24, 25, 26).

[0058] Specifically, each secondary winding is concentrically wound on the column of the same sub-frame iron core with the primary winding, and the secondary winding is arranged on the outside of the primary winding. The secondary winding 31 is concentrically wound on the outside of the primary winding 21 on the left column of the first sub-frame iron core, the secondary winding 32 is concentrically wound on the outside of the primary winding 22 on the right column of the first sub-frame iron core, the secondary winding 33 is concentrically wound on the outside of the primary winding 23 on the left column of the second sub-frame iron core, the secondary winding 34 is concentrically wound on the outside of the primary winding 24 on the right column of the second sub-frame iron core, the secondary winding 35 is concentrically wound on the outside of the primary winding 25 on the left column of the third sub-frame iron core, and the secondary winding 36 is concentrically wound on the outside of the primary winding 26 on the right column of the first sub-frame iron core.

[0059] In this embodiment, the secondary winding is concentrically arranged outside the primary winding, which increases the coupling coefficient between the primary and secondary windings, effectively reduces the leakage reactance between the primary and secondary windings of the transformer, and improves the efficiency of the transformer.

[0060] In one embodiment, Figure 2 、 Figure 3 as well as Figure 4 As shown, six primary windings with opposite polarities are connected in series in pairs into three groups, and then connected in Y connection, D connection or YN connection.

[0061] Specifically, the six primary windings include HVA1 and HVA2, wound around the left and right columns of the first sub-frame core; HVB1 and HVB2, wound around the left and right columns of the second sub-frame core; and HVC1 and HVC2, wound around the left and right columns of the third sub-frame core. After the six primary windings are connected in series to form three groups with opposite polarity, they can be connected to the three-phase power grid in various ways, including Y, D, and YN connections.

[0062] Among them, the example of connecting two primary windings of adjacent frame cores in series with opposite polarities is used for explanation. The tail end of the primary winding HVA1 is connected in series with the tail end of the primary winding HVB1 to form a group, the tail end of the primary winding HVC1 is connected in series with the tail end of the primary winding HVA2 to form a group, and the tail end of the primary winding HVB2 is connected in series with the tail end of the primary winding HVC2 to form a group.

[0063] Furthermore, if Figure 2 The figure shows that three sets of primary windings connected in series are connected to the three-phase power grid end in a Y-type connection. The first end of the primary winding HVA1, the first end of the primary winding HVC1 and the first end of the primary winding HVB2 are used to connect to the three terminals of the three-phase power supply. The first end of the primary winding HVB1, the first end of the primary winding HVA2 and the first end of the primary winding HVC2 are connected to the same point. Figure 3The figure shows that three sets of primary windings connected in series are connected to the three-phase power grid using a YN connection. The first end of the primary winding HVA1, the first end of the primary winding HVC1 and the first end of the primary winding HVB2 are used to connect to the three terminals of the three-phase power grid. The first end of the primary winding HVB1, the first end of the primary winding HVA2 and the first end of the primary winding HVC2 are connected to the same point and are also grounded through this point. Figure 4 The figure shows that three sets of primary windings connected in series are connected to the three-phase power grid end in a D-type connection form. The first end of the primary winding HVA1, the first end of the primary winding HVC1 and the first end of the primary winding HVB2 are used to connect to the three terminals of the three-phase power grid. The first end of the primary winding HVB1 is connected to the first end of the primary winding HVB2, the first end of the primary winding HVA2 is connected to the first end of the primary winding HVA1, and the first end of the primary winding HVC2 is connected to the first end of the primary winding HVC1.

[0064] In this embodiment, the problem of single primary winding connection form of the existing ferromagnetic triple frequency transformer is solved.

[0065] In one embodiment, Figure 2 、 Figure 3 and Figure 4 As shown, the six primary windings are wound in the same direction on the core.

[0066] Specifically, when power is applied, there is a phase difference between the electromotive force phasors of the winding coils, thereby generating magnetic flux on the core. Therefore, the six primary windings are wound on the split core in the same winding direction, and their head ends are as follows: Figure 2 、 Figure 3 as well as Figure 4 The end marked with a dot is the end without a dot. The three-phase electricity is input from the first end of each of the six windings, that is, the first ends of the six primary windings are all endpoints with positive electromotive force, that is, the ends with the same name.

[0067] In this embodiment, by setting the same winding direction and the same-named ends, and the three-phase power supply having a phase difference of 120°, the three-phase fundamental waves in the iron cores of each frame can be offset.

[0068] In one embodiment, Figure 5 As shown, six secondary windings of the same polarity are connected in parallel in pairs and then connected in an open triangle connection.

[0069] Specifically, the six secondary windings include secondary windings LVA1 and LVA2 wound on the left and right columns of the first sub-frame core, secondary windings LVB1 and LVB2 wound on the left and right columns of the second sub-frame core, and secondary windings LVC1 and LVC2 wound on the left and right columns of the third sub-frame core. The six secondary windings are connected in parallel to form three groups with the same polarity, then connected in an open delta configuration to the single-phase terminal.

[0070] like Figure 5 As shown, the secondary winding LVA1 and the secondary winding LVA2 are connected in parallel with the same polarity, the secondary winding LVB1 and the secondary winding LVB2 are connected in parallel with the same polarity, the secondary winding LVC1 and the secondary winding LVC2 are connected in parallel with the same polarity, the tail end of the secondary winding LVA1 and the secondary winding LVA2 is connected to the head end of the secondary winding LVB1 and the secondary winding LVB2, the tail end of the secondary winding LVB1 and the secondary winding LVB2 is connected to the head end of the secondary winding LVC1 and the secondary winding LVC2, and the head end of the secondary winding LVA1 and the secondary winding LVA2 and the tail end of the secondary winding LVC1 and the secondary winding LVC2 are connected to the single-phase end.

[0071] In one embodiment, Figure 5 As shown, the winding direction of the six secondary windings on the core is the same. Specifically, the six secondary windings are wound on the frame core in the same winding direction, and as shown Figure 5 The middle dots are the endpoints where the electromotive force of each secondary winding is positive, i.e., the same-named terminals. In this embodiment, by using the same winding direction and the same-named terminals, and by having a 120° phase difference between the three-phase power supplies, the three-phase fundamental waves in the cores of each sub-frame can be offset.

[0072] In one embodiment, the three-frame split triple-frequency transformer further includes six voltage-regulating windings, which are respectively connected to six secondary windings. The six voltage-regulating windings are also concentrically wound on the left and right columns of the first sub-frame iron core, the second sub-frame iron core and the third sub-frame iron core.

[0073] Specifically, six voltage-regulating windings are connected in series with a corresponding secondary winding, thereby varying the number of turns on the secondary winding of the triple-frequency transformer. When the voltage-regulating windings are wound with the same polarity and direction as the secondary winding, the number of turns on the secondary winding is increased. When the voltage-regulating windings are wound in opposite directions, the number of turns on the secondary winding is reduced.

[0074] Furthermore, the six voltage regulating windings are also wound on the left and right columns of each sub-frame iron core. They can be set on the outside of the first winding and the second winding, or in the middle of the first winding and the second winding, or on the inside of the first winding and the second winding, close to the iron core, but are not limited to this.

[0075] In this embodiment, the voltage regulating winding is added to increase or decrease the magnetic flux in the frame core of the triple frequency transformer of the present application, thereby producing an effect of adjustable secondary output voltage.

[0076] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A three-frame split triple frequency transformer, characterized in that: include: Iron core and winding; the iron core includes a first sub-frame iron core, a second sub-frame iron core and a third sub-frame iron core; the winding includes six primary windings and six secondary windings, and the primary windings and the secondary windings are grouped in pairs and concentrically wound on the opposite columns of the first sub-frame iron core, the second sub-frame iron core and the third sub-frame iron core. After the six primary windings are connected in series in pairs with opposite polarities into three groups, they are connected in D connection or YN connection and then connected to the three-phase terminal. After the six secondary windings are connected in parallel in pairs with the same polarity, they are connected in open triangle connection 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-frame split type triple frequency transformer according to claim 1, characterized in that: The first frame core, the second frame core, and the third frame core are all rectangular frame cores with equal areas.

3. The three-frame split type triple frequency transformer according to claim 2, characterized in that: The first frame core, the second frame core, and the third frame core are wound cores or laminated cores.

4. The three-frame split-type triple frequency transformer according to claim 3, characterized in that: The first sub-frame iron core, the second sub-frame iron core and the third sub-frame iron core are arranged in the same oil tank or are respectively arranged in three independent oil tanks.

5. The three-frame split type triple frequency transformer according to claim 1, characterized in that: The six secondary windings are arranged outside the six primary windings.

6. The three-frame split-type triple frequency transformer according to claim 5, characterized in that: The six primary windings are wound in the same direction on the core.

7. The three-frame split-type triple frequency transformer according to claim 6, characterized in that: The six secondary windings are wound in the same direction on the core.

8. The three-frame split-type triple frequency transformer according to any one of claims 1 to 7, characterized in that: It also includes six voltage-regulating windings, which are respectively connected to the six secondary windings. The six voltage-regulating windings are also concentrically wound on the left and right columns of the first sub-frame iron core, the second sub-frame iron core and the third sub-frame iron core.

9. The three-frame split-type triple frequency transformer according to claim 8, characterized in that: The voltage regulating winding and the secondary winding are wound with the same polarity and in the same direction.

10. The three-frame split-type triple frequency transformer according to claim 8, characterized in that: The voltage regulating winding is arranged outside the secondary winding.

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