Coreless transformer coil

Abstract

The utility model discloses a coreless transformer coil, including the coil, the coil every turn line width is different, and the interval between adjacent turns is determined through simulation, makes the self -induction loss of coil minimum. The utility model can effectively reduce the high -frequency loss of coreless transformer coil.

Description

Technical Field

[0001] This utility model relates to the field of electronic power technology, and in particular to a coreless transformer coil. Background Technology

[0002] Coreless transformers, as a new type of isolation device, have advantages such as small size, low cost, and high transmission efficiency, and are widely used in power electronic systems such as switching power supplies, motor drives, and inverters. However, the coils of coreless transformers generate significant losses at high frequencies, especially in the primary winding. Traditional coil design methods typically use fixed line widths and spacings, which are insufficient to effectively reduce high-frequency losses. Utility Model Content

[0003] To overcome the above-mentioned defects, this utility model aims to provide a coreless transformer coil that can reduce the equivalent series resistance of the coreless transformer coil under high-frequency operating conditions, thereby reducing losses and improving the transmission efficiency of the coreless transformer.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0005] A coreless transformer coil includes a coil, wherein each turn of the coil has a different wire width, and the spacing between adjacent turns is determined by simulation to minimize the self-inductance loss of the coil.

[0006] Preferably, the innermost turn of the coil has the smallest line width.

[0007] Preferably, the coil has 8 turns, and the line width of the coil increases sequentially from the first turn to the sixth turn from the inside out, and decreases sequentially from the sixth turn to the eighth turn.

[0008] Preferably, the inner diameter of the coil is 2.688 mm and the outer diameter of the coil is 5.116 mm.

[0009] Preferably, the line width of the first turn of the coil is 0.11 mm.

[0010] Preferably, the spacing between adjacent turns of the first to seventh turns of the coil is 0.22mm, 0.13mm, 0.13mm, 0.12mm, 0.12mm, and 0.148mm, respectively.

[0011] The beneficial effects of this utility model are as follows:

[0012] 1. This utility model can effectively reduce the high-frequency loss of coreless transformer coils through variable line width design.

[0013] 2. This utility model, while keeping the coreless transformer coil and volume unchanged, can significantly reduce the equivalent series resistance R. ESRAt the same time, the self-inductance loss is small and the coupling coefficient is also improved. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of Example 1.

[0015] Figure 2 This is a graph showing the relationship between the unit loss of a coreless transformer coil and the magnetic field strength.

[0016] Figure 3 This is a schematic diagram illustrating the effect of coil line width on coil loss in a coreless transformer.

[0017] Figure 4 The effect of varying coil turn spacing on the equivalent series resistance R ESR A graph showing the influence of self-perception. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with the accompanying drawings.

[0019] Example 1

[0020] This embodiment discloses a coreless transformer coil, including a coil with different wire widths for each turn. The spacing between adjacent turns is determined through simulation to minimize the self-inductance loss of the coil. The innermost turn of the coil has the smallest wire width.

[0021] In this embodiment, the coil has 8 turns. The line width of the coil increases sequentially from the first turn to the sixth turn from the inside out, and decreases sequentially from the sixth turn to the eighth turn.

[0022] The inner diameter of the coil is 2.688mm, and the outer diameter of the coil is 5.116mm; the line width of the first turn of the coil is 0.11mm; the spacing between adjacent turns of the first to seventh turns of the coil are 0.22mm, 0.13mm, 0.13mm, 0.12mm, 0.12mm, and 0.148mm, respectively.

[0023] Example 2

[0024] Based on Example 1, this example discloses the optimized design process of the coreless transformer coil disclosed in Example 1, as follows:

[0025] Under high-frequency operating conditions, the coil of a coreless transformer can be considered as an equivalent series resistance R. ESR In series with an inductor, R ESR This is also the real part of the inductive impedance. When an alternating current I is passed through the coil, its high-frequency loss R... LOSS for:

[0026] R LOSS =I2 ×R ESR

[0027] It can be seen that the loss generated by the coreless transformer in the high-frequency circuit is caused by its series equivalent resistance. Therefore, the loss caused by the coil can be reduced by reducing the series equivalent resistance of the coil.

[0028] The following will provide further explanation using specific simulation examples:

[0029] The coil was modeled and simulated using Maxwell simulation software to determine the relationship between coil loss and winding thickness h, line width W, operating frequency f, and magnetic field strength H.

[0030] First, the relationship between magnetic field strength and winding unit loss is investigated, and the simulation results are as follows: Figure 2 As shown, there is a clear positive correlation between magnetic field strength and winding unit loss. With increasing magnetic field strength, winding unit loss also increases accordingly.

[0031] Next, the magnetic field strength was set to a constant value, and the relationship between the unit loss of the winding and the winding line width was studied. The simulation results are as follows: Figure 3 As shown, it can be seen that as the winding width increases, the unit loss of the winding decreases significantly in the initial short distance, then rises to a certain value and tends to stabilize.

[0032] Through the Figure 2 and Figure 3 Comprehensive analysis shows that, with a constant magnetic field strength, there exists an optimal value for the winding linewidth that minimizes winding losses. Therefore, the coil linewidth can be optimized to find the linewidth that minimizes losses.

[0033] Next, we explored an optimization scheme for the coil linewidth. The number of turns in the coreless transformer coil was set to 8, with its inner and outer diameters remaining constant. Based on this, the linewidth of each coil turn was set to different values, and simulation analysis was performed. The final optimized coil linewidth scheme was determined as follows: the linewidth of the first turn is the smallest, then gradually increases until reaching the maximum linewidth of the sixth turn, followed by a gradual decrease in linewidth for the seventh and eighth turns.

[0034] The coil parameters before and after optimization are compared. Tables 1 and 2 list the coil geometric parameters and electrical performance before and after optimization, respectively.

[0035] Table 1 Initial Coil Parameters

[0036] Inner diameter / mm 2.688mm outer diameter / mm 5.116mm Line width / mm 0.114mm Spacing / mm 0.186mm Inductance value / nH 680nH <![CDATA[R ESR / Oh]]> 2.7Ω Coupling coefficient 0.8

[0037] Table 2. Coil parameters after linewidth optimization

[0038] Inner ring width / mm 0.11mm Spacing / mm 0.125mm Self-sensitivity / nH 630.7nH <![CDATA[R ESR / Oh]]> 1.85Ω Coupling coefficient 0.83

[0039] Comparing Tables 1 and 2, it can be seen that after the linewidth optimization, the coil ESR decreased by about 28% and the coil self-inductance loss was nearly 3.2% while the coupling coefficient with the secondary coil increased from 0.8 to 0.83.

[0040] Simulation analysis shows that if the coil spacing is a fixed value, it cannot be guaranteed that the spacing of each coil turn is optimal. Therefore, based on the optimization of coil linewidth, it is necessary to explore the impact of the spacing of each coil turn on ESR.

[0041] Similar to the coil linewidth optimization exploration, when optimizing coil spacing, the inner and outermost turns of the coil are fixed to ensure the coil size remains constant. Then, the scanning function of Maxwell simulation software is used, starting from the 7th turn to determine its optimal spacing, and the position of this turn is fixed. The spacing of the 6th turn is then scanned to determine the optimal spacing, and this cycle continues until the 2nd turn. The spacing per turn is related to the coil R... ESR Relationship with self-perception, such as Figure 4 As shown.

[0042] analyze Figure 4 The coil structure parameters after spacing optimization were obtained. The coil parameters after spacing optimization are shown in Table 3.

[0043] Table 3 Coil parameters after optimized spacing

[0044] Inner ring width / mm 0.11mm Spacing G2 / mm 0.22mm Spacing G3 / mm 0.13mm Spacing G4 / mm 0.13mm Spacing G5 / mm 0.12mm Spacing G6 / mm 0.12mm Spacing G7 / mm 0.148mm Self-sensitivity / nH 600nH <![CDATA[R ESR / Oh]]> 1.83Ω Coupling coefficient 0.86

[0045] According to the analysis in Table 3, the coil self-inductance loss is less than 1.5% after the spacing optimization, which is 40% lower than the coil self-inductance error in Table 2. In addition, the coupling coefficient with the secondary coil also increased from 0.83 to 0.86.

[0046] In summary, (1) after optimizing the coil linewidth, the coil ESR decreased by about 30% and the coil self-inductance loss was nearly 3.2% while the coupling coefficient with the secondary coil increased from 0.8 to 0.83. (2) based on the optimization of the coil linewidth, the line spacing was further optimized. After the spacing was optimized, the coil self-inductance loss was less than 1.5%, and the coupling coefficient of the original secondary coil was increased from 0.83 to 0.86.

[0047] Of course, there may be other embodiments of this utility model. Without departing from the spirit and essence of this utility model, those skilled in the art can make various corresponding changes and modifications based on this utility model, but these corresponding changes and modifications should all fall within the protection scope of the appended claims of this utility model.

Claims

1. A coreless transformer coil, characterized in that, The coil includes a coil with a different wire width per turn, and the spacing between adjacent turns is determined through simulation to minimize the self-inductance loss of the coil. The innermost turn of the coil has the smallest line width; The coil has 8 turns, and the line width of the coil increases sequentially from the first turn to the sixth turn from the inside out, and decreases sequentially from the sixth turn to the eighth turn.

2. The coreless transformer coil according to claim 1, characterized in that, The inner diameter of the coil is 2.688 mm, and the outer diameter of the coil is 5.116 mm.

3. The coreless transformer coil according to claim 2, characterized in that, The line width of the first turn of the coil is 0.11 mm.

4. The coreless transformer coil according to claim 3, characterized in that, The spacing between adjacent turns of the first to seventh turns of the coil are, respectively: 0.22mm, 0.13mm, 0.13mm, 0.12mm, 0.12mm, and 0.148mm.

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