CN114188135A - High-voltage isolation flat-plate transformer based on guiding equipotential lines and optimization method thereof - Google Patents

Abstract

The invention belongs to the technical field of flat transformers, and particularly relates to a high-voltage isolation flat transformer based on a guided equipotential line and an optimization method thereof, aiming at solving the problems of large volume, heavy weight, low power density, complex insulation design, poor reliability and low voltage withstanding level of the conventional flat transformer. The invention comprises the following steps: the magnetic core penetrates through the low-voltage winding and the high-voltage winding to form a closed magnetic circuit; the high-voltage windings are arranged on the magnetic core in parallel, and the positions of the high-voltage windings are overlapped and connected through the blind holes; the low-voltage windings are arranged on the upper side and the lower side of the high-voltage winding on the magnetic core in parallel, and the low-voltage windings are overlapped in position and connected through via holes; and the electric field control unit is arranged between the high-voltage winding and the low-voltage winding at intervals in parallel and guides a potential line between the high-voltage winding and the low-voltage winding. The invention has the advantages of uniform electric field distribution, small electric field intensity in air, small volume, large power density, simple structure, good parameter consistency and low cost, and reduces partial discharge.

Description

High-voltage isolation flat-plate transformer based on guiding equipotential lines and optimization method thereof

Technical Field

The invention belongs to the technical field of flat transformers, and particularly relates to a high-voltage isolation flat transformer based on a guiding equipotential line and an optimization method thereof.

Background

In recent years, power electronic transformers, renewable energy direct-current grid-connected converters and the like are widely researched and applied, break through the functional scope of conventional industrial frequency transformers, can realize the functions of voltage grade conversion, electrical isolation, power regulation and control, access of a plurality of alternating-current/direct-current ports and the like between low-voltage and medium-voltage power grids, and are regarded as one of key technologies of energy internet.

The high-capacity high-voltage withstand voltage high-frequency transformer is a key core component of a power electronic transformer and a renewable energy direct-current grid-connected converter, and is used for realizing core functions of high-voltage and low-voltage electrical isolation, voltage grade conversion, power transmission and the like. The conversion efficiency, power density and reliability of high frequency transformers are critical to the safe, stable and efficient operation of the converter and system. With the continuous deepening of novel power electronic technologies such as power electronic transformers in the fields of alternating current-direct current hybrid power distribution networks/micro-grids, new energy medium-voltage direct current grid connection, electric automobile quick charging stations, data center power supply, locomotive traction power supply and the like, the application requirements of high-voltage isolation, high efficiency, high power density and high reliability are put forward for high-frequency transformers.

The traditional high-voltage isolation high-frequency transformer realizes higher isolation voltage resistance by adding solid, liquid, gas insulation and other modes on the basis of the structure of the conventional high-frequency transformer, but the high-voltage isolation high-frequency transformer has the defects of very low power density caused by larger volume and weight, complex structure, complex insulation design and poor reliability, and the consistency of product parameters is difficult to ensure in the production process, thereby seriously restricting the application of the high-voltage isolation high-frequency transformer in the fields of high requirements on power density, such as electric automobile quick-charging stations, data center power supply, locomotive traction power supply and the like.

The flat transformer is a novel structural form of a high-frequency transformer, a flattened structure is adopted, and a winding is generally formed by copper foil or PCB (printed circuit board) lamination, so that the height is greatly reduced. Because the flat transformer has small volume and compact structure and the insulation distance between the primary winding and the secondary winding is limited, the flat transformer is mainly applied to the application with lower isolation and voltage resistance requirements (less than or equal to 4kV) at present.

The problem of high voltage insulation design under high power density is always the bottleneck problem of the development of high-voltage isolation high-frequency transformers, and the popularization and application of the power electronic transformer technology in multiple fields are severely restricted while the reduction of the system cost is limited.

Disclosure of Invention

In order to solve the above problems in the prior art, namely the problems that the traditional transformer has large volume, heavy weight, low power density, complex insulation design and poor reliability, and the existing flat-plate transformer has low voltage withstanding level (less than or equal to 4kV), the invention provides a high-voltage isolation flat-plate transformer based on a guided equipotential line, wherein the transformer is constructed based on a circuit board and comprises a low-voltage winding, a high-voltage winding, an insulating medium, a magnetic core and an electric field control unit;

the magnetic core penetrates through the low-voltage winding and the high-voltage winding to form a closed magnetic circuit;

the high-voltage windings are arranged on the magnetic core in parallel, and the positions of the high-voltage windings are overlapped and connected through the blind holes;

the low-voltage winding is arranged on the upper side and the lower side of the high-voltage winding on the magnetic core in parallel and is parallel to the high-voltage winding, and the low-voltage winding is overlapped in position and connected through a through hole;

the insulating medium is arranged among all the high-voltage windings, among the low-voltage windings and among the high-voltage windings and the low-voltage windings;

and the electric field control units are arranged between the high-voltage winding and the low-voltage winding in parallel at intervals.

In some preferred embodiments, the electric field control unit is preferably implemented by using an electric field control copper foil.

In some preferred embodiments, the transformer further comprises n electric field control copper foils disposed between the high voltage winding and the low voltage winding, wherein the 1 st electric field control copper foil is adjacent to the low voltage winding and the nth electric field control copper foil is adjacent to the high voltage winding.

In some preferred embodiments, the high voltage winding has an extended terminal portion more than the low voltage winding.

In some preferred embodiments, the electric field control copper foils are provided with extension outlet terminals, the k electric field control copper foil extension outlet terminal is partially overlapped with the k-1 electric field control copper foil extension outlet terminal, and the k electric field control copper foil extends to the high-voltage winding extension outlet terminal by a preset copper foil offset distance.

In some preferred embodiments, the electric field control copper foil and the insulating medium form a plurality of distributed capacitors which are connected in series between the low-voltage winding and the high-voltage winding.

In some preferred embodiments, the electric field controls the copper foil such that the voltage distribution in a direction parallel to the winding of the circuit board is uniform.

In some preferred embodiments, the electric field control copper foil has a potential that decreases in a gradient from the high-voltage winding to the low-voltage winding.

In some preferred embodiments, in operation, a high frequency current flows in the high voltage winding and generates a high frequency magnetic field in the magnetic core, which in turn induces a high frequency current in the low voltage winding.

In another aspect of the present invention, a method for optimizing a high-voltage isolation transformer based on a guiding equipotential line is provided, which is applied to the high-voltage isolation planar transformer based on the guiding equipotential line, and includes:

s100, selecting a substrate material and a dielectric thickness based on breakdown field intensity, dielectric constant and loss factor; the PCB can be selected as a substrate material;

s200, determining a PCB size boundary condition as a design threshold value of electric field control unit optimization based on an isolation voltage working condition of an original secondary side of the high-voltage isolation flat-plate transformer and the maximum electric field design strength and the maximum air electric field design strength of each point of the substrate material;

step S300, determining a laminating mode of a high-voltage winding and a low-voltage winding and the number of turns of the high-voltage winding and the low-voltage winding according to the primary and secondary working voltage, current and power; the lamination mode comprises staggered lamination and lamination of the three-mingmuir method;

s400, setting the initial layer number of the electric field control copper foil and the staggered distance between the copper foils, and calculating the electric field intensity of each point in the substrate material and the electric field intensity in the air by a calculation, simulation or test method based on the laminating mode and the substrate material parameters;

step S500, judging whether the electric field intensity of each point in the substrate material and the electric field intensity in the air are greater than the optimized design threshold of the electric field control unit and the electric field distribution is uniform;

step S600, if the judgment result in the step S500 is larger than or the electric field distribution is not uniform, the method of the step S300-the step S500 is repeated to adjust the laminating mode of the high-voltage winding and the low-voltage winding, the initial layer number of the copper foils and the staggered distance between the copper foils until the electric field intensity of each point in the substrate material and the electric field intensity in the air are smaller than or equal to the optimized design threshold value of the electric field control unit and the electric field distribution is uniform, and the overall size of the PCB, the substrate material, the dielectric thickness, the laminating mode, the layer number of the copper foils and the staggered distance between the copper foils are determined;

step S700, if the overall size of the PCB exceeds the PCB size boundary condition, repeating the method from step S300 to step S600 until the size of the PCB winding meets the set PCB size boundary condition, and obtaining high-voltage insulation design parameters of the transformer;

and S800, manufacturing a high-voltage isolation flat transformer according to the high-voltage insulation design parameters, and working under the working condition of the isolation voltage of the primary side and the secondary side.

The invention has the beneficial effects that:

(1) the high-voltage isolation flat-plate transformer adopts the electric field control unit to guide the distribution of the surrounding electric field, eliminates the problem of electric field distortion in the air, reduces the electric field intensity in the air, reduces the possibility of partial discharge in the air, greatly reduces the volume, has simple structure and improves the power density of the transformer compared with the conventional structure of increasing an insulation gap or adopting a high-voltage cable terminal.

(2) The high-voltage isolation flat-plate transformer fully utilizes the excellent and mature processing technology of the PCB and the PCB insulating medium, the proposed PCB winding has a simple structure, and higher voltage isolation can be realized without additional insulating measures.

(3) According to the high-voltage isolation flat-plate transformer, the high-voltage winding and the low-voltage winding are realized through the multiple layers of copper foils in the PCB, the working frequency is high, the power density is high, and the PCB is benefited from high processing precision, so that the flat-plate transformer based on the PCB winding has good parameter consistency.

(4) According to the high-voltage isolation flat-plate transformer, the low-voltage winding and the high-voltage winding are overlapped, the low-voltage winding completely covers the high-voltage winding, high-voltage solid insulation between the high-voltage winding and the low-voltage winding is achieved through the PCB insulating medium, and the electric field intensity in the air around the high-voltage winding is reduced. And because the low-voltage winding is arranged on the outer layer of the PCB and is small to the ground potential, the safe grounding of the magnetic core of the transformer can be conveniently realized.

(5) The high-voltage isolation flat-plate transformer has the advantages that the PCB winding processing and manufacturing cost is low, the precision is high, the parasitic parameter can be controlled, the parameter consistency of batch processing is good, and the high-voltage isolation flat-plate transformer is particularly suitable for the modularized series-parallel connection application of power electronic transformers.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a high voltage isolation planar transformer based on a guided equipotential line according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a structural principle of a high-voltage isolation planar transformer based on equipotential guiding in an embodiment of the present invention;

FIG. 3 is a schematic diagram of the structure of a conventional planar transformer and its electric field distribution;

FIG. 4 is an equivalent circuit diagram of an electric field control unit in the embodiment of the present invention;

FIG. 5 is an equivalent circuit diagram of a conventional planar transformer where the high voltage winding is disconnected from the low voltage winding;

FIG. 6 is a comparison graph of the simulation results of the electric field strength finite elements of the high voltage isolation flat transformer and the conventional flat transformer in the embodiment of the present invention

Detailed Description

The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, for convenience of description, only the portions related to the related invention are shown in the drawings.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

The invention provides a high-voltage isolation flat transformer based on equipotential line guiding, which adopts an electric field control unit to guide the distribution of a surrounding electric field, eliminates the problem of electric field distortion in the air, reduces the electric field intensity in the air, reduces the possibility of partial discharge in the air, greatly reduces the volume and has simple structure and improves the power density of the transformer compared with the conventional structure of increasing an insulation gap or adopting a high-voltage cable terminal.

The transformer is constructed on the basis of a circuit board and comprises a low-voltage winding, a high-voltage winding, an insulating medium, a magnetic core and an electric field control unit;

the magnetic core penetrates through the low-voltage winding and the high-voltage winding to form a closed magnetic circuit;

the high-voltage windings are arranged on the magnetic core in parallel, and the positions of the high-voltage windings are overlapped and connected through the blind holes;

the low-voltage winding is arranged on the upper side and the lower side of the high-voltage winding on the magnetic core in parallel and is parallel to the high-voltage winding, and the low-voltage winding is overlapped in position and connected through a through hole;

the insulating medium is arranged among all the high-voltage windings, among the low-voltage windings and among the high-voltage windings and the low-voltage windings;

and the electric field control units are arranged between the high-voltage winding and the low-voltage winding in parallel at intervals.

In order to more clearly describe the equipotential line guiding-based high-voltage isolation planar transformer of the present invention, the following describes the modules in the embodiment of the present invention in detail with reference to fig. 1 and 2.

The high-voltage isolation flat-plate transformer based on the guidance equipotential line provided by the embodiment comprises a circuit board construction, a low-voltage winding 1, a high-voltage winding 2, an insulating medium 3, a magnetic core 4 and an electric field control unit 5; the circuit board is usually a PCB circuit board;

the magnetic core 4 penetrates through the low-voltage winding 1 and the high-voltage winding 2 to form a closed magnetic circuit;

the high-voltage windings 2 are arranged on the magnetic core 4 in parallel, and the positions of the high-voltage windings 2 are overlapped and connected through blind holes;

in the present embodiment, the high-voltage winding 2 has a larger extended end portion than the low-voltage winding 1.

When the high-frequency magnetic field generator works, high-frequency current flows in the high-voltage winding 2, a high-frequency magnetic field is generated in the magnetic core 4, and then the high-frequency magnetic field induces high-frequency current in the low-voltage winding 1, so that the isolated transmission of electric energy is realized.

The low-voltage winding 1 is arranged on the upper side and the lower side of the high-voltage winding 2 on the magnetic core 4 in parallel and is parallel to the high-voltage winding 2, and the low-voltage winding 1 is overlapped in position and connected through a through hole; the low voltage winding can be regarded as a shielding layer of the high voltage winding, and in fig. 2, except for the edge part of the winding, the electric field is uniformly distributed in the direction parallel to the winding; in the direction perpendicular to the windings, the potential gradually decreases. Because the PCB insulating medium with higher withstand voltage is arranged between the high-voltage winding and the low-voltage winding, and the high-voltage electric field is uniformly distributed and applied to the insulating medium, the PCB windings except the edge of the windings can bear higher voltage.

The transformer further comprises n electric field control copper foils arranged between the high-voltage winding and the low-voltage winding, wherein the No. 1 electric field control copper foil is adjacent to the low-voltage winding, and the No. n electric field control copper foil is adjacent to the high-voltage winding. Each electric field control copper foil has a suspension potential, and the potential is reduced in a gradient manner from the high-voltage winding to the low-voltage winding, namely the potential gradient of the electric field control copper foil adjacent to the high-voltage winding is reduced to the electric field control copper foil adjacent to the low-voltage winding.

The insulating medium 3 is arranged among all the high-voltage windings 2, among the low-voltage windings 1 and among the high-voltage windings 2 and the low-voltage windings 1; the insulating medium is used for isolating the voltage between the high-voltage windings 2, between the low-voltage windings 1 and between the high-voltage windings 2 and the low-voltage windings 1;

in the conventional flat transformer, as shown in fig. 3, since the high and low voltage windings are suddenly disconnected in the direction parallel to the PCB and a uniformly distributed high voltage electric field is applied to the insulating medium, the PCB windings except the winding edges can withstand a higher voltage. The electric field distribution is not uniform any more, so that the electric field intensity is concentrated at the edge of the low-voltage winding and seriously distorted, the field intensity at the broken part of the winding is gradually enhanced along with the increase of the voltage applied between the high-voltage winding and the low-voltage winding in the traditional flat-plate transformer equivalent circuit as shown in figure 5, the potential difference at two ends of the air equivalent capacitor Cp1 is gradually increased, and the high electric field intensity easily causes partial discharge and even breakdown in the air on the surface of the PCB, so that the faults of partial discharge, insulation failure and the like are caused.

And the electric field control units are arranged between the high-voltage winding 2 and the low-voltage winding 1 in parallel at intervals. Preferably with an electric field controlled copper foil. The electric field control copper foils are provided with extension leading-out ends, the kth electric field control copper foil extension leading-out end 6 is partially overlapped with the kth-1 electric field control copper foil extension leading-out end 6, and the kth electric field control copper foil extends towards the high-voltage winding extension leading-out end by a preset copper foil staggering distance. The electric field control unit controls the electric field distribution around the disconnection position of the low-voltage winding 1 and the high-voltage winding 2, and reduces the electric field intensity in the air. The electric field control copper foil and the insulating medium form a plurality of distributed capacitors which are connected in series between the low-voltage winding and the high-voltage winding, and an equivalent circuit is shown in figure 4. The distributed capacitors are connected in series to play a voltage dividing role, so that voltage distribution in the direction parallel to the PCB winding is uniform, and the problems of electric field distortion, local discharge caused by overlarge field intensity and the like existing at the overlapped edge of the low-voltage winding and the high-voltage winding in the conventional high-voltage isolation PCB winding are solved. As shown in fig. 2, the present application guides equipotential lines to a uniformly distributed state.

The electric field control copper foil is distributed on the upper layer and the lower layer of the input and output parts of the high-voltage winding and completely covers the upper layer and the lower layer, so that the electric field control copper foil can play a role in shielding an electric field.

The electric field control copper foil makes the voltage distribution in the direction parallel to the circuit board winding uniform. The potential of the transformer is reduced in a gradient manner from the direction of the high-voltage winding to the direction of the low-voltage winding.

Compared with the conventional insulation design, the method for increasing the insulation distance, filling special materials and the like greatly reduces the volume of the PCB electric field control unit, has simple process, does not influence the normal work of the high-frequency flat-plate transformer, and is beneficial to improving the power density of the transformer.

The low-voltage winding is arranged on the outer layer of the PCB, the high-voltage winding is arranged on the inner layer of the PCB, and the multiple layers of windings are connected through buried holes or blind holes. Therefore, the low-voltage winding and the PCB stress control unit coat the high-voltage winding in the PCB together, and the problem of electric field concentration in the air is solved. Meanwhile, the problem of insulation between the transformer magnetic core and the low-voltage winding based on the structure is solved, and the reliable operation of the flat-plate transformer is guaranteed.

A second embodiment of the present invention provides a method for optimizing a high-voltage isolation transformer based on a guiding equipotential line, which is applied to the above-mentioned high-voltage isolation planar transformer based on a guiding equipotential line, and the method includes:

s100, selecting a substrate material and a dielectric thickness based on breakdown field intensity, dielectric constant and loss factor; the PCB can be selected as a substrate material;

the circuit board of the embodiment is realized by adopting a PCB substrate, FR-4 material can be adopted, the model of the FR-4 material and the thickness of the PCB substrate are selected, FR-4 epoxy resin S1180 is selected as the PCB substrate material in the embodiment, and the typical breakdown field strength is 60 Kv/mm.

S200, determining a PCB size boundary condition as a design threshold value of electric field control unit optimization based on an isolation voltage working condition of an original secondary side of the high-voltage isolation flat-plate transformer and the maximum electric field design strength of the substrate material and the maximum electric field design strength of air;

in the embodiment, 20% of the typical breakdown field strength of the S1180 medium is taken as the maximum electric field design strength, namely 12kV/mm, the maximum air electric field design strength is set to be 2kV/mm, and the length and width threshold values of the PCB are determined to be 15cm and 10 cm.

Step S300, determining a laminating mode of a high-voltage winding and a low-voltage winding and the number of turns of the high-voltage winding and the low-voltage winding according to the primary and secondary working voltage, current and power; the lamination mode comprises staggered lamination and sandwich lamination; the lamination mode of primary side-secondary side-primary side is overlapped in a staggered way, and the lamination mode of primary side-secondary side-primary side is overlapped by the sandwich method;

in this embodiment, the isolation operating voltage between the high-voltage winding 2 and the low-voltage winding 1 is set to be 20kV, the high-voltage winding adopts 2 turns, and the low-voltage winding adopts 2 turns.

S400, setting the initial layer number of the electric field control copper foil and the staggered distance between the copper foils, and calculating the electric field intensity of each point in the substrate material and the electric field intensity in the air by a calculation, simulation or test method based on the laminating mode and the substrate material parameters;

in the embodiment, the initial layer number is 8, the staggered distance between copper foils is 4mm, the maximum field intensity in the PCB insulating medium is 8.5kV/mm and the maximum field intensity in the air is 1.9kV/mm by a finite element simulation method;

step S500, judging whether the electric field intensity of each point in the substrate material and the electric field intensity in the air are greater than the optimized design threshold of the electric field control unit and the electric field distribution is uniform;

step S600, if the judgment result in the step S500 is larger than or the electric field distribution is not uniform, the method of the step S300-the step S500 is repeated to adjust the laminating mode of the high-voltage winding and the low-voltage winding, the initial layer number of the copper foils and the staggered distance between the copper foils until the electric field intensity of each point in the substrate material and the electric field intensity in the air are smaller than or equal to the optimized design threshold value of the electric field control unit and the electric field distribution is uniform, and the size of the PCB winding, the substrate material, the dielectric thickness, the laminating mode, the layer number of the copper foils and the staggered distance between the copper foils are determined;

the highest field intensity is 8.5kV/mm, and the highest field intensity in the air is 1.9kV/mm, which meets the design threshold.

Step S700, if the overall size of the PCB exceeds the PCB size boundary condition, repeating the method from the step S100 to the step S600 until the size of the PCB winding meets the set PCB size boundary condition, and obtaining high-voltage insulation design parameters of the transformer;

on the basis of meeting the requirement of an electric field design threshold, the length and the width of the PCB are 14.8cm and 8cm respectively, the requirement of size setting of the flat-plate transformer is met, and the selected parameters are high-voltage insulation design parameters.

And S800, manufacturing a high-voltage isolation flat transformer according to the high-voltage insulation design parameters, and working under the working condition of the isolation voltage of the primary side and the secondary side.

Fig. 2 is a schematic cross-sectional view of a high-isolation withstand voltage planar transformer according to an embodiment of the high-voltage isolation planar transformer of the present invention, where a PCB has a 16-layer structure, low-voltage windings are distributed on the 1 st layer and the 16 th layer, and high-voltage windings are distributed on the 8 th layer and the 9 th layer. The electric field control copper foils are distributed on the 1 st to 16 th layers, namely 8 layers of the electric field control copper foils on the upper side and the lower side of the high-voltage winding. For the convenience of comparative analysis, in a finite element simulation model, the upper side of the high-voltage winding adopts the optimization method of the flat-plate transformer provided by the invention, and the lower side of the high-voltage winding does not adopt other measures, namely the winding structure of the conventional flat-plate transformer. The simulation result of the conventional flat-plate transformer is shown in the lower half of fig. 6, in the conventional flat-plate winding structure below the high-voltage winding, the electric field at the disconnection position of the high-voltage winding and the low-voltage winding is very concentrated, and the field intensity (6.5kV/mm) in the air is far higher than the set electric field intensity threshold (2 kV/mm). In order to solve the problem, the PCB electric field control unit is additionally arranged for the high-voltage isolation flat-plate transformer, the simulation result is shown in the upper half part of figure 6, and it can be seen that after the PCB electric field control unit is adopted on the upper side of the high-voltage winding, the electric field intensity in the air at the disconnection part of the low-voltage winding is reduced to be less than 1.9kV/mm, the electric field intensity in the PCB is uniformly distributed from the high-voltage winding to the low-voltage winding, the electric field intensity in the PCB insulating medium is 8.5kV/mm at most, and the designed electric field intensity threshold value is met.

The terms "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing or implying a particular order or sequence.

The terms "comprises," "comprising," or any other similar term are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.

Claims (10)

1. A high-voltage isolation flat-plate transformer based on a guided equipotential line is characterized in that the transformer is constructed based on a circuit board and comprises a low-voltage winding, a high-voltage winding, an insulating medium, a magnetic core and an electric field control unit;

the magnetic core penetrates through the low-voltage winding and the high-voltage winding to form a closed magnetic circuit;

the high-voltage windings are arranged on the magnetic core in parallel, and the positions of the high-voltage windings are overlapped and connected through the blind holes;

the low-voltage winding is arranged on the upper side and the lower side of the high-voltage winding on the magnetic core in parallel and is parallel to the high-voltage winding, and the low-voltage winding is overlapped in position and connected through a through hole;

the insulating medium is arranged among all the high-voltage windings, among the low-voltage windings and among the high-voltage windings and the low-voltage windings;

and the electric field control units are arranged between the high-voltage winding and the low-voltage winding in parallel at intervals.

2. The equipotential line-guided high-voltage isolated planar transformer according to claim 1, wherein the field control unit is preferably implemented using field-controlled copper foil.

3. The isopotential line guided high voltage isolation planar transformer of claim 2 further comprising n field control copper foils disposed between the high voltage winding and the low voltage winding, wherein the 1 st field control copper foil is adjacent to the low voltage winding and the nth field control copper foil is adjacent to the high voltage winding.

4. The equipotential line-guided high voltage isolation planar transformer of claim 3, wherein the high voltage winding has an extended terminal portion that is larger than the extended terminal portion of the low voltage winding.

5. The equipotential line guiding-based high-voltage isolated planar transformer of claim 4, wherein the field control copper foils each have an extended outlet, the kth field control copper foil extended outlet partially overlaps the kth-1 field control copper foil extended outlet, and the kth field control copper foil extends toward the high-voltage winding extended outlet by a predetermined copper foil offset distance.

6. The isopotential line guiding-based high voltage isolation planar transformer of claim 5 wherein said field control copper foil, together with the insulating medium, forms a plurality of distributed capacitors connected in series between the low voltage winding and the high voltage winding.

7. The equipotential line-guided high-voltage isolation planar transformer of claim 2, wherein the electric field controls the copper foil to make a voltage distribution in a direction parallel to the winding of the circuit board uniform.

8. The isopotential line guiding-based high voltage isolation planar transformer of claim 1 wherein said electric field control copper foil has a potential gradient decreasing from the high voltage winding to the low voltage winding.

9. The isopotential line based high voltage isolation planar transformer of claim 1 wherein in operation a high frequency current flows through the high voltage winding and generates a high frequency magnetic field in the core, which in turn induces a high frequency current in the low voltage winding.

10. A method for optimizing a high-voltage isolation transformer based on a guided equipotential line, the method being applied to the high-voltage isolation planar transformer based on a guided equipotential line of any one of claims 1 to 9, the method comprising:

s100, selecting a substrate material and a dielectric thickness based on breakdown field intensity, dielectric constant and loss factor; the PCB can be selected as a substrate material;

s200, determining a PCB size boundary condition as a design threshold value of electric field control unit optimization based on an isolation voltage working condition of an original secondary side of the high-voltage isolation flat-plate transformer and the maximum electric field design strength and the maximum air electric field design strength of each point of the substrate material;

step S300, determining a laminating mode of a high-voltage winding and a low-voltage winding and the number of turns of the high-voltage winding and the low-voltage winding according to the primary and secondary working voltage, current and power; the lamination mode comprises staggered lamination and lamination of the three-mingmuir method;

s400, setting the initial layer number of the electric field control copper foil and the staggered distance between the copper foils, and calculating the electric field intensity of each point in the substrate material and the electric field intensity in the air by a calculation, simulation or test method based on the laminating mode and the substrate material parameters;

step S500, judging whether the electric field intensity of each point in the substrate material and the electric field intensity in the air are greater than the optimized design threshold of the electric field control unit and the electric field distribution is uniform;

step S600, if the judgment result in the step S500 is larger than or the electric field distribution is not uniform, the method of the step S300-the step S500 is repeated to adjust the laminating mode of the high-voltage winding and the low-voltage winding, the initial layer number of the copper foils and the staggered distance between the copper foils until the electric field intensity of each point in the substrate material and the electric field intensity in the air are smaller than or equal to the optimized design threshold value of the electric field control unit and the electric field distribution is uniform, and the overall size of the PCB, the substrate material, the dielectric thickness, the laminating mode, the layer number of the copper foils and the staggered distance between the copper foils are determined;

step S700, if the overall size of the PCB exceeds the PCB size boundary condition, repeating the method from step S300 to step S600 until the size of the PCB winding meets the set PCB size boundary condition, and obtaining high-voltage insulation design parameters of the transformer;

and S800, manufacturing a high-voltage isolation flat transformer according to the high-voltage insulation design parameters, and working under the working condition of the isolation voltage of the primary side and the secondary side.

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