High-power high-frequency high-direct-current bias transformer based on super Fe-Si-Al

Abstract

The invention discloses a high-power high-frequency high-direct-current bias transformer based on super Fe-Si-Al, which relates to the technical field of power electronic transformers and comprises a magnetic conductive core body, a primary winding and a secondary winding, the magnetic conductive core body is made of a super Fe-Si-Al magnetic powder core; the primary winding and the secondary winding are both wound by excitation wires and are alternately wound on a magnetic column of the magnetic conductive core body in a close coupling mode of one turn and one turn. The primary winding and the secondary winding are both formed by winding excitation wires and are alternately wound on the magnetic column of the magnetic core body in a one-turn and one-turn tight coupling mode, so that the primary winding and the secondary winding are coupled to the maximum extent in space, and leakage inductance is greatly reduced to below 10 mu H from more than 100 mu H of a traditional transformer; therefore, energy feedback and voltage spikes in the high-frequency switching process are effectively reduced, switching loss is remarkably reduced, and the overall conversion efficiency of the system is improved.

Description

Technical Field

[0001] This invention relates to the field of power electronic transformer technology, specifically to a high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum alloy. Background Technology

[0002] In modern power electronics fields such as new energy vehicle charging, energy storage systems, and industrial high-frequency power supplies, transformers, as core components for energy conversion, directly affect the efficiency, power density, and operational stability of the entire system. With technological advancements, systems are trending towards higher frequencies, smaller sizes, and higher power densities, which places extremely stringent requirements on key transformer performance indicators such as leakage inductance, magnetizing inductance, and DC bias capability.

[0003] Traditional transformers typically use ferrite or ordinary silicon steel sheets as magnetic conductors. Ferrite materials have low losses at high frequencies, but their saturation flux density is low, typically 0.3T-0.5T, resulting in weak DC bias capability. When a large DC current needs to be superimposed on the secondary winding of the transformer, such as in charging or energy storage applications, the ferrite core is prone to saturation, leading to drastic fluctuations in output voltage and unstable system operation. Although ordinary silicon steel sheets have a high saturation flux density, their high-frequency losses are extremely high, mainly eddy current losses and hysteresis losses, making them unsuitable for high-frequency operating environments above 5kHz, resulting in low efficiency and significant heat generation. Furthermore, traditional transformers generally employ a layered winding structure, i.e., the primary winding is wound completely first, and then the secondary winding is wound around it, or vice versa. This structure results in a large spatial separation between the primary and secondary windings, a low coupling coefficient, and a large leakage inductance, typically greater than 100μH. In high-frequency switching power supplies, a large leakage inductance can cause voltage spikes, increasing the stress and losses of switching devices and reducing the overall efficiency and reliability of the system. Super iron-silicon-aluminum, as a high-performance soft magnetic material, possesses high saturation magnetic flux density (1.0T-1.2T), low high-frequency loss, and excellent DC bias characteristics. However, simply replacing traditional magnetic cores with it without targeted design of the overall transformer structure, especially the winding arrangement, still fails to address issues such as high leakage inductance and insufficient magnetizing inductance, thus failing to fully leverage the material's advantages.

[0004] To address this, a high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum alloy to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum, comprising a magnetic core and windings, wherein the windings include a primary winding and a secondary winding; The magnetic core is made of super iron-silicon-aluminum magnetic powder core; Both the primary and secondary windings are wound with excitation wire and are alternately wound on the magnetic core in a tightly coupled manner, one turn after another.

[0007] Preferably, the composition of the super iron-silicon-aluminum magnetic powder core, by mass percentage, is: Fe 84.8%-85.3%, Si 9.5%-9.7%, Al 5.2%-5.4%.

[0008] Preferably, the magnetic core is composed of multiple independent super iron-silicon-aluminum magnetic powder cores spliced ​​into a square-shaped structure.

[0009] Preferably, the ratio of the width to the height of the magnetic core window of the magnetic core is 1:3, and the cross-sectional area of ​​the magnetic column of the magnetic core is 120cm² to 125cm².

[0010] Preferably, the excitation wire comprises multiple copper cores with a single diameter of 0.1 mm twisted together, the surface of the copper cores is covered with a polyimide varnish layer, and the wire bodies of the primary winding and the secondary winding are covered with a self-adhesive polyimide film insulation layer.

[0011] Preferably, the number of turns in the primary winding is equal to the number of turns in the secondary winding.

[0012] Preferably, both the primary winding and the secondary winding have 34 turns.

[0013] Preferably, it also includes aluminum plates disposed at the upper and lower ends of the magnetic core, the two aluminum plates being connected by fastening screws, the aluminum plate located below the magnetic core being fixedly connected to a base, and a mica sheet insulating layer being disposed between the aluminum plate and the magnetic core.

[0014] Preferably, its operating frequency range is 5kHz-100kHz.

[0015] Preferred: When the secondary winding carries a 125A AC load and is superimposed with a 125A DC current, its output voltage fluctuation amplitude is ≤1%.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. By using excitation wire for both the primary and secondary windings and alternating them on the magnetic core in a tightly coupled manner, the primary and secondary windings are coupled to the maximum extent in space, which significantly reduces the leakage inductance from more than 100μH in traditional transformers to less than 10μH. This effectively reduces energy feedback and voltage spikes during high-frequency switching, significantly reduces switching losses, and improves the overall conversion efficiency of the system.

[0017] 2. This transformer utilizes the high initial permeability of super iron-silicon-aluminum material, enabling the transformer's excitation inductance to reach over 1mH. A higher excitation inductance means a smaller no-load excitation current, reducing excitation losses and ensuring that the transformer can operate stably and efficiently in a wide frequency range, typically 5kHz-100kHz.

[0018] 3. This transformer utilizes the super iron-silicon-aluminum material with a saturation magnetic flux density of up to 1.0T-1.2T, enabling it to withstand a DC bias current of up to 125A on the secondary side while simultaneously carrying an AC load of 125A without core saturation. The output voltage remains stable with fluctuations of ≤1%, meeting the stringent requirements for handling large DC components in scenarios such as charging new energy vehicles. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings. It is obvious that the drawings described below are merely some embodiments of the present invention, and other drawings can be obtained by those skilled in the art based on these drawings without any inventive effort. Wherein: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the arrangement of the primary winding and the secondary winding in this invention; Figure 3 This is a schematic diagram of the magnetic core window structure in this invention.

[0020] 1. Magnetic core; 101. Aluminum plate; 102. Winding; 103. Fastening screws; 2. Base. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0023] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0024] Reference Figure 1 As shown, this invention provides a technical solution for a high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum alloys: A high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum alloy includes a magnetic core 1 and a winding 102, wherein the winding 102 includes a primary winding and a secondary winding. The magnetic core 1 is made of super iron-silicon-aluminum alloy magnetic powder. Both the primary and secondary windings are wound with excitation wire and are alternately wound on the magnetic posts of the magnetic core 1 in a tightly coupled manner, one turn after another.

[0025] Working principle: Since both the primary and secondary windings are wound with excitation wire and alternately wound on the magnetic core in a tightly coupled manner, the primary and secondary windings are coupled to the maximum extent in space, which greatly reduces the leakage inductance from more than 100μH in traditional transformers to less than 10μH. This effectively reduces energy feedback and voltage spikes in the high-frequency switching process, significantly reduces switching losses, and improves the overall conversion efficiency of the system.

[0026] This transformer utilizes the high initial permeability of super iron-silicon-aluminum material, enabling the transformer's excitation inductance to reach over 1mH. A higher excitation inductance means a smaller no-load excitation current, reducing excitation losses and ensuring that the transformer can operate stably and efficiently in a wide frequency range, typically 5kHz-100kHz.

[0027] This transformer utilizes the super iron-silicon-aluminum material with a saturation magnetic flux density of up to 1.0T-1.2T, enabling it to withstand a DC bias current of up to 125A on the secondary side while simultaneously carrying an AC load of 125A without core saturation. The output voltage remains stable with fluctuations of ≤1%, meeting the stringent requirements for handling large DC components in scenarios such as charging new energy vehicles.

[0028] It should be noted that the manufacturing process of this transformer includes the following three main steps: Step 1: Preparation of Super Iron-Silicon-Aluminum Magnetic Powder Core. First, Fe, Si, and Al raw materials are accurately weighed according to their mass percentages and then smelted. Next, alloy powder is prepared using a high-pressure nitrogen atomization method, and the alloy powder is then subjected to an insulating coating treatment. Finally, the treated powder is pressed into shape and subjected to annealing heat treatment to obtain the super iron-silicon-aluminum magnetic powder core.

[0029] Step 2: Winding. Using excitation wire, the primary and secondary windings are alternately wound on the magnetic core composed of multiple super iron-silicon-aluminum magnetic powder cores in a tightly coupled manner, one turn after another.

[0030] Step 3: Assembly and Insulation. The wound magnetic core is mechanically fixed, and the winding leads are connected and insulated, thus completing the fabrication of this transformer.

[0031] In an optional embodiment, the composition of the super iron-silicon-aluminum magnetic powder core, by mass percentage, is: Fe 84.8%-85.3%, Si 9.5%-9.7%, and Al 5.2%-5.4%. It should be noted that this precise composition ratio ensures that the material simultaneously possesses high saturation magnetic flux density and low high-frequency losses, with Si increasing resistivity to reduce eddy current losses and Al optimizing DC bias characteristics.

[0032] By controlling the Fe content within the range of 84.8%-85.3%, a good foundation of magnetic permeability is provided for the magnetic powder core, which is crucial for ensuring the transformer's magnetic conductivity. The Si content of 9.5%-9.7% effectively increases the alloy's resistivity. When the transformer operates at high frequencies, high resistivity significantly reduces the generation of eddy currents within the core, thereby reducing eddy current losses and ensuring the transformer's efficiency under high-frequency conditions. The Al content of 5.2%-5.4% works synergistically with Fe and Si to further optimize the DC bias characteristics of the magnetic powder core. This allows the core to maintain good magnetic stability even when subjected to large DC bias currents, preventing magnetic saturation. This is essential for the stable operation of the transformer in scenarios requiring the handling of large DC components, such as charging of new energy vehicles.

[0033] In an optional embodiment, the magnetic core 1 is composed of multiple independent super iron-silicon-aluminum magnetic powder cores assembled into a U-shaped structure. It should be noted that this structure has a symmetrical magnetic circuit and high window utilization.

[0034] By assembling multiple independent super iron-silicon-aluminum magnetic powder cores into a U-shape, the size and number of cores can be flexibly adjusted according to actual power requirements, facilitating the design and production of transformers with different power ratings. Simultaneously, the spliced ​​structure reduces the processing difficulty of individual magnetic powder cores during production, resulting in a higher yield. Even if a single core is defective, only that part needs to be replaced, eliminating the need for complete scrapping and effectively reducing production costs and material waste. Furthermore, the U-shaped structure provides good magnetic circuit closure and low magnetic leakage, reducing electromagnetic interference to surrounding electronic components and improving the electromagnetic compatibility of the entire transformer system. High window utilization means that more winding turns can be accommodated within the same space, or thicker wires can be used to reduce winding losses, which is beneficial for improving the power density and efficiency of the transformer. During assembly, the splicing points are fixed and insulated with special insulating adhesive to ensure that no eddy currents are generated between the cores, while also ensuring the mechanical strength and stability of the overall structure, enabling it to withstand vibrations and temperature changes under high-power, high-frequency operating conditions.

[0035] In an optional embodiment, the ratio of the width to the height of the core window of the magnetic core 1 is 1:3 to accommodate a tight winding arrangement; the cross-sectional area of ​​the magnetic post of the magnetic core 1 is 120cm² to 125cm². It should be noted that the magnetizing inductance is increased by increasing the magnetic cross-sectional area.

[0036] It should be further explained that the appropriate selection of the cross-sectional area of ​​the magnetic core can, on the one hand, reduce the magnetic flux density of the magnetic core during high-frequency operation, reduce hysteresis loss and eddy current loss, thereby improving the working efficiency of the transformer; on the other hand, a larger magnetic core cross-sectional area also provides a better heat dissipation basis for the magnetic core, which helps to dissipate the heat generated by the magnetic core during operation in a timely manner, and avoids the magnetic performance stability and service life of the magnetic core due to excessively high local temperature.

[0037] In an optional embodiment, the excitation wire comprises multiple strands of copper cores, each with a diameter of 0.1 mm, twisted together. The surface of the copper cores is covered with a polyimide varnish layer, and the primary and secondary windings are externally covered with a self-adhesive polyimide film insulation layer as the main insulation layer. It should be noted that the fine-diameter multi-strand stranded wire can effectively suppress the skin effect and proximity effect at high frequencies, reducing AC resistance (copper loss).

[0038] It should be further noted that the polyimide varnish layer possesses excellent high-temperature resistance (long-term operating temperature can reach above 220℃) and electrical insulation properties, ensuring reliable insulation between the copper cores and preventing partial discharge under high frequency and high voltage. The self-adhesive polyimide film insulation layer not only further strengthens the insulation strength between the primary and secondary windings, but its self-adhesive properties also allow the films to bond together after winding is completed by heating, improving the overall compactness and structural stability of the windings. This reduces the risk of insulation wear caused by winding loosening or displacement under high-frequency vibration, and also facilitates the conduction of internal heat to external heat dissipation structures through the insulation layer.

[0039] In one optional embodiment, the number of turns in the primary winding is equal to the number of turns in the secondary winding. In another optional embodiment, both the primary and secondary windings have 34 turns. It should be noted that this equal number of turns setting is suitable for 1:1 voltage conversion applications and facilitates tightly alternating winding.

[0040] It should be further noted that the tightly alternating winding method ensures a highly symmetrical spatial distribution of the primary and secondary windings on the core, effectively reducing leakage inductance between windings and minimizing energy loss during high-frequency signal transmission. Simultaneously, the equal turns design allows for the use of dual-wire parallel winding in the winding process, further enhancing the symmetry and consistency of the windings. This helps reduce electromagnetic interference caused by imbalances in winding parameters, ensuring stable operation of the transformer under high-power, high-frequency conditions.

[0041] In an optional embodiment, the magnetic core 1 is further provided with aluminum plates 101 at the upper and lower ends. The two aluminum plates 101 are connected by fastening screws 103. The aluminum plate 101 located below the magnetic core 1 is fixedly connected to a base 2. A mica sheet insulating layer is provided between the aluminum plate 101 and the magnetic core 1. It should be noted that the aluminum plate 101 helps to dissipate heat, and the mica sheet insulating layer provides reliable external insulation.

[0042] It should be further noted that the aluminum plate 101 has excellent thermal conductivity, enabling it to quickly transfer the heat generated during transformer operation from the inside to the surface of the aluminum plate 101. This heat is then dissipated into the surrounding environment through natural convection or forced air cooling, effectively controlling the transformer's temperature rise and preventing excessive temperature from affecting its performance and service life. The mica sheet insulation layer, as a high-performance inorganic insulating material, possesses extremely high insulation strength and temperature resistance. Its placement between the aluminum plate 101 and the magnetic core 1 forms a robust insulating barrier between the live components inside the transformer and the aluminum plate 101, preventing the aluminum plate 101 from becoming energized and ensuring the safety of operators and the safe use of the equipment. Simultaneously, the mica sheet insulation layer also possesses good mechanical strength and chemical stability, enabling it to adapt to vibrations, temperature changes, and other operating conditions during transformer operation, maintaining stable insulation performance over the long term and providing strong support for the reliable operation of the transformer.

[0043] In an optional embodiment, the operating frequency range of this transformer is 5kHz-100kHz. When the secondary winding carries a 125A AC load and is superimposed with a 125A DC current, the output voltage fluctuation of this transformer is ≤1%, that is, the magnetic core is unsaturated and the temperature rise is controllable.

[0044] It should be further explained that the achievement of the above performance indicators is due to the excellent high-frequency characteristics and high saturation magnetic flux density inherent in the super iron-silicon-aluminum magnetic core material itself. Within a wide operating frequency range of 5kHz to 100kHz, the super iron-silicon-aluminum magnetic core can effectively reduce hysteresis losses and eddy current losses, ensuring that the transformer maintains high efficiency under high-frequency conditions. More importantly, when the secondary winding simultaneously carries a 125A AC load current and a 125A DC bias current, the combined total current significantly enhances the magnetization effect on the magnetic core. If the magnetic core saturates under these conditions, the inductance will drop sharply, the excitation current will increase significantly, and this will lead to severe distortion and fluctuations in the output voltage. However, the super iron-silicon-aluminum magnetic core used in this embodiment, with its high saturation magnetic flux density, can maintain stable permeability even under such high DC bias conditions, thereby effectively suppressing output voltage fluctuations and keeping their amplitude within 1%, strongly demonstrating that the magnetic core has not entered a saturation state. Meanwhile, combined with the efficient heat dissipation design of the aforementioned aluminum alloy shell and the reliable insulation of the mica sheet, the overall temperature rise of the transformer can be precisely controlled within a safe range, avoiding performance degradation or safety hazards caused by overheating, and ensuring long-term stable operation under complex load conditions.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum alloy, characterized in that: It includes a magnetic core (1) and a winding (102), wherein the winding (102) includes a primary winding and a secondary winding; The magnetic core (1) is made of super iron-silicon-aluminum magnetic powder core; Both the primary and secondary windings are wound with excitation wire and are alternately wound on the magnetic core (1) in a tightly coupled manner, one turn after another.

2. The high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum as described in claim 1, characterized in that: The composition of the super iron-silicon-aluminum magnetic powder core, by mass percentage, is: Fe 84.8%-85.3%, Si 9.5%-9.7%, Al 5.2%-5.4%.

3. A high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum as described in claim 1 or 2, characterized in that: The magnetic core (1) is composed of multiple independent super iron-silicon-aluminum magnetic powder cores spliced ​​into a square-shaped structure.

4. A high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum as described in claim 1, characterized in that: The ratio of the width to the height of the magnetic core window of the magnetic core (1) is 1:3, and the cross-sectional area of ​​the magnetic column of the magnetic core (1) is 120cm² to 125cm².

5. A high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum according to claim 1, characterized in that: The excitation wire comprises multiple strands of copper cores, each with a diameter of 0.1 mm, twisted together. The surface of the copper cores is covered with a polyimide varnish layer, and the primary and secondary windings are covered with a self-adhesive polyimide film insulation layer.

6. A high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum as described in claim 1, characterized in that: The number of turns in the primary winding is equal to the number of turns in the secondary winding.

7. A high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum as described in claim 6, characterized in that: Both the primary winding and the secondary winding have 34 turns.

8. A high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum according to claim 1, characterized in that: It also includes aluminum plates (101) disposed at the upper and lower ends of the magnetic core (1), the two aluminum plates (101) are connected by fastening screws (103), the aluminum plate (101) located below the magnetic core (1) is fixedly connected to a base (2), and a mica sheet insulating layer is disposed between the aluminum plate (101) and the magnetic core (1).

9. A high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum as described in claim 1, characterized in that: Its operating frequency range is 5kHz-100kHz.

10. A high-power, high-frequency, high-DC bias transformer based on super iron-silicon-aluminum according to claim 9, characterized in that: When the secondary winding carries a 125A AC load and is superimposed with a 125A DC current, its output voltage fluctuation is ≤1%.

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