Planar transformer leakage inductance control method based on winding sequence
By controlling the leakage inductance of a planar transformer through winding sequence, the problem of precise control of leakage inductance in existing technologies is solved. It achieves precise control of leakage inductance without the use of a magnetic shunt, is applicable to multi-turn transformers, has low computational load, small error, and meets engineering design requirements.
Patent Information
- Application Number
- CN202511080119.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-04
- Publication Date
- 2025-11-21
AI Technical Summary
Existing technologies make it difficult to precisely control the transformer leakage inductance in LLC resonant converters to meet the numerical requirements of the resonant inductance without using a magnetic shunt.
By using a winding sequence-based method, the magnetic field strength at the end of the preceding winding is calculated, the coil type is determined, and the winding arrangement is adjusted to control leakage inductance, including placing the primary or secondary coil at the end of the preceding winding until the target leakage inductance is achieved.
It achieves precise control of the leakage inductance of planar transformers without the use of magnetic shunts, with low computational load, applicable to multi-turn transformers, rapid results, small error, and meets engineering design requirements.
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Figure CN120998656A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of planar transformer, in particular to a planar transformer leakage inductance control method based on winding sequence. BACKGROUND
[0002] LLC resonant converter has been widely used in new energy vehicles, data centers and other high-power applications. Based on the characteristics of zero-voltage turn-on of the primary side switch tube and zero-current turn-off of the secondary side rectifier diode, LLC resonant converter can effectively reduce switching loss. In the topology structure of LLC resonant converter, both the resonant inductor and the main transformer need to use magnetic cores, and these magnetic elements occupy a large part of the circuit area. In order to further improve the power density of LLC resonant converter, current research focuses on integrating resonant inductor and main transformer into the same magnetic core, i.e. magnetic integration technology.
[0003] There are mainly two technical routes for current magnetic integration technology. The first method integrates resonant inductor and main transformer by sharing magnetic circuit, such as using magnetic integration technology of matrix transformer. The second method selects to use the leakage inductance of the transformer: the equivalent position of the leakage inductance of the transformer in the circuit is the same as the position of the resonant inductor in the resonant cavity, so it is feasible to use the leakage inductance of the transformer as the resonant inductor of the LLC resonant circuit. In the past, the value of the leakage inductance of the transformer was small, which was difficult to meet the numerical requirements of the resonant inductor; but as the working frequency of LLC resonant converter increases, the numerical value of the resonant inductor required thereby decreases, so the magnetic integration method using the leakage inductance of the transformer has a larger application space in high-frequency applications. Magnetic integration using the leakage inductance of the transformer needs to accurately control the leakage inductance, and the commonly used method to control the leakage inductance of the transformer is to insert a magnetic shunt between the upper and lower magnetic cores, and to obtain the required leakage inductance by controlling the material and size of the magnetic shunt. However, as the numerical value of the resonant inductor required by the LLC resonant converter decreases, the magnetic shunt becomes unnecessary, and therefore, a transformer leakage inductance control technology without using a magnetic shunt is urgently needed. SUMMARY
[0004] The technical problem to be solved by the present application is to provide a planar transformer leakage inductance control method based on winding sequence, which can control the leakage inductance of the planar transformer to the required value without using a magnetic shunt.
[0005] The technical solution adopted by the present application to solve the technical problem is to provide a planar transformer leakage inductance control method based on winding sequence, comprising the following steps:
[0006] Place one turn of the primary coil on the first layer and perform the following determination process:
[0007] Calculate the magnetic field intensity at the end of the pre-winding, and determine the type of a turn of coil placed at the end of the pre-winding according to the magnetic field intensity, to obtain a temporary winding; wherein the pre-winding is a winding whose arrangement sequence has been determined;
[0008] Calculate the maximum achievable leakage inductance of the temporary winding, and compare the maximum achievable leakage inductance of the temporary winding with a preset target leakage inductance, and determine the winding arrangement mode according to the comparison result;
[0009] Repeat the determination process until the primary coil or the secondary coil is exhausted, and place the remaining coils at the end of the pre-winding to obtain the final winding arrangement.
[0010] The type of a turn of coil placed at the end of the pre-winding is determined according to the magnetic field intensity, specifically including:
[0011] If the magnetic field intensity at the end of the pre-winding is greater than zero, a turn of secondary coil is placed at the end of the pre-winding;
[0012] If the magnetic field intensity at the end of the pre-winding is less than or equal to zero, a turn of primary coil is placed at the end of the pre-winding.
[0013] The maximum achievable leakage inductance of the temporary winding is the leakage inductance of a planar transformer obtained by arranging the remaining primary coils and secondary coils in a completely non-interleaved structure with the temporary winding as the pre-winding, and the arrangement form is determined according to the magnetic field intensity at the end of the pre-winding; when the magnetic field intensity at the end of the pre-winding is greater than zero, the primary coil is arranged in front and the secondary coil is arranged in back; when the magnetic field intensity at the end of the pre-winding is less than or equal to zero, the primary coil is arranged in back and the secondary coil is arranged in front.
[0014] The winding arrangement mode is determined according to the comparison result, specifically including:
[0015] If the maximum achievable leakage inductance of the temporary winding is greater than or equal to the target leakage inductance, the winding arrangement mode is the arrangement mode of the temporary winding;
[0016] If the maximum achievable leakage inductance of the temporary winding is less than the target leakage inductance, the type of a turn of coil at the end of the temporary winding is changed.
[0017] The technical solution adopted by the present application to solve its technical problems is to provide a planar transformer wound according to the final winding arrangement determined by the above-mentioned planar transformer leakage inductance control method based on winding sequence.
[0018] Advantages
[0019] Compared with the prior art, the present application has the following advantages and positive effects: according to the magnetic field intensity at the end of the pre-winding, the coil wound at the end of the pre-winding is determined, and whether the type of the coil wound at the end of the pre-winding is modified is determined by comparing the maximum reachable leakage inductance of the temporary coil with the target leakage inductance, so that the leakage inductance of the planar transformer obtained in this way can be accurately controlled at the required value, and the calculation amount is small, and the result can be quickly obtained in the case of a large number of turns of the transformer. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 is a schematic diagram of the magnetic field intensity and the winding arrangement;
[0021] Figure 2 is a flow chart of the winding sequence-based planar transformer leakage inductance control method of the embodiment of the present application;
[0022] Figure 3 is a planar transformer leakage inductance design flow chart with a turn ratio of 16:12 in the embodiment of the present application. DETAILED DESCRIPTION
[0023] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not used to limit the scope of the present application. In addition, it should be understood that after reading the content taught by the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.
[0024] The leakage inductance of the planar transformer can be calculated by the energy stored in the magnetic core window: part of the magnetic flux generated by the primary winding leaks into the magnetic core window, so that the primary winding and the secondary winding are not completely coupled, resulting in the generation of leakage inductance, and therefore the energy stored in the magnetic core window is the energy of the leakage inductance. The leakage inductance L of the planar transformer lk can be calculated by the following formula:
[0025]
[0026] wherein μ0 is the magnetic permeability of vacuum; I p is the current flowing through the primary coil; l is the average length of the winding, b is the average width of the winding, and h is the thickness of the winding layer; H is the magnetic field intensity in the winding layer. In the case where the size parameters are determined, the leakage inductance of the planar transformer is proportional to the integral of the square of the magnetic field intensity H in the winding layer in the thickness direction of the winding. The magnetic field intensity distribution in the winding layer is determined by the winding arrangement sequence, and each turn of the primary coil increases the value of the magnetic field intensity H in the winding layer each turn of the secondary coil decreases the value of H I sFor the current flowing through the secondary coil, the value of the magnetic field strength H in the interval layer remains unchanged in the winding layer. Therefore, adjusting the arrangement order of the primary coil and the secondary coil can change the leakage inductance of the planar transformer, and by selecting a suitable winding arrangement, the transformer can have a specific leakage inductance. Based on this theory, the embodiment proposes a winding order-based planar transformer leakage inductance control method.
[0027] For a planar transformer with known primary and secondary coil turns, when the primary and secondary coils are arranged in a completely non-interleaved structure, the leakage inductance of the transformer is the largest. For a planar transformer with known primary and secondary coil turns and a number of turns arranged, the maximum leakage inductance it can achieve is also calculable. The winding with a determined arrangement order is called a pre-order winding. In the case of a pre-order winding, the maximum leakage inductance that the transformer can achieve is defined as the maximum achievable leakage inductance of the pre-order winding, that is, for a specific pre-order winding, the remaining winding is arranged in a completely non-interleaved form, and the leakage inductance of the planar transformer obtained in the above manner is calculated. The obtained leakage inductance is the maximum achievable leakage inductance of the pre-order winding. When calculating its maximum achievable leakage inductance, it is necessary to determine whether to arrange the primary coil first or the secondary coil first when arranging the remaining winding according to the direction of the magnetic field strength H at the end of the pre-order winding: when the magnetic motive force of the primary coil is positive and the magnetic field strength H at the end of the pre-order winding is > 0, the primary coil is arranged first and the secondary coil is arranged second when arranging the remaining winding; when the magnetic field strength H at the end of the pre-order winding is ≤ 0, the secondary coil is arranged first and the primary coil is arranged second when arranging the remaining winding. As shown in FIG. 1, the magnetic field strength H at the end of the pre-order winding is > 0, so when the remaining winding is arranged in a completely non-interleaved form, the structure in which the primary coil is arranged first and the secondary coil is arranged second (structure A) has a larger leakage inductance, and the leakage inductance of structure A is the maximum achievable leakage inductance of the pre-order winding. Figure 1
[0028] The winding order-based planar transformer leakage inductance control method of the embodiment can reduce the maximum achievable leakage inductance of the transformer as much as possible through interleaving of the primary and secondary coils while ensuring that the maximum achievable leakage inductance is not less than the target leakage inductance. In the embodiment, the number of turns of the primary coil of the transformer is n p ; the number of turns of the secondary coil is n s ; the winding arrangement is arr; 'p' in the winding arrangement expression represents one turn of the primary coil, and's' represents one turn of the secondary coil; the target leakage inductance is L target ; and the leakage inductance of the transformer is L lk . As shown in FIG. 2, the method specifically includes the following steps: Figure 2
[0029] Step 1: Place one turn of the primary coil on the first layer, and at this time the winding arrangement arr = 'p'.
[0030] Step 2: Calculate the magnetic field strength H at the end of the preceding winding, and determine the type of the coil at the end of the preceding winding based on the magnetic field strength H, thus obtaining the temporary winding. Specifically, determining the type of the coil at the end of the preceding winding based on the magnetic field strength H involves:
[0031] If the magnetic field strength H at the end of the preceding winding is greater than zero, then a secondary coil is placed at the end of the preceding winding, resulting in a temporary winding arr. temp =arr+'s';
[0032] If the magnetic field strength H at the end of the preceding winding is less than or equal to zero, then a single turn of the primary coil is placed at the end of the preceding winding, resulting in a temporary winding arr. temp =arr+'p'.
[0033] Step 3: Calculate the maximum achievable leakage inductance of the temporary winding, compare it with the preset target leakage inductance, and determine the winding arrangement based on the comparison result. Specifically, determining the winding arrangement based on the comparison result in this step is as follows:
[0034] If the temporary winding arr temp Maximum achievable leakage L lkr Greater than or equal to the target leakage inductance L target L lkr ≥L target The winding arrangement is the same as that of temporary windings, i.e., arr = arr temp ;
[0035] If the temporary winding arr temp Maximum achievable leakage L lkr Less than the target leakage inductance L target L lkr <L target If the type of the last turn of the temporary winding is changed, that is, the operation in step 2 is canceled and the opposite operation is performed. That is, if the magnetic field strength H at the end of the current winding is greater than zero, then arr = arr + 'p'; if the magnetic field strength H at the end of the current winding is less than or equal to zero, then arr = arr + 's'.
[0036] Step 4: Repeat steps 2 and 3 until the primary or secondary coil is exhausted. Place the remaining coil at the end of the preceding winding to obtain the final winding arrangement.
[0037] Therefore, the leakage inductance control method for planar transformers based on winding sequence in this embodiment has low computational complexity and can be applied to planar transformers with a large number of turns. The method in this embodiment requires a maximum of n iterations. p +ns , and with the increase of the number of turns of the transformer, the influence of the arrangement of each turn coil on the overall leakage inductance decreases, thereby improving the precision of controlling the leakage inductance.
[0038] The following takes a planar transformer with a coil turn ratio of 16:12 as an example for illustration, the flowchart is as shown in Figure 3 The model of the magnetic core used is EQ30 / 8 / 20, the thickness of the primary and secondary coil layers is 70 μm, the thickness of the interval layer is 300 μm, the average length of the winding is 57 mm, and the average width is 5 mm. The target leakage inductance is set to 4 μH, and the final winding arrangement of the planar transformer obtained by using the method of the embodiment is 'pspspspspssssssssppppppppppp', the calculated value of the leakage inductance is 4.034 μH, and the error of the obtained transformer leakage inductance and the target leakage inductance is 0.85%. The obtained structure is simulated and verified by using FEA simulation, the simulation value of the leakage inductance is 3.934 μH, and the error of the target leakage inductance is 1.65%, which can meet the engineering design requirements.
[0039] It can be found that, according to the magnetic field intensity at the end of the pre-winding, the coil wound at the end of the pre-winding is determined, and whether the type of the coil wound at the end of the pre-winding is modified is determined by comparing the maximum reachable leakage inductance of the temporary coil with the target leakage inductance, and by this way, the planar transformer obtained can accurately control the leakage inductance to the required value, and the calculation amount is small, and the result can be quickly obtained in the case of a large number of turns of the transformer.
[0040] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer usable storage media containing computer usable program code (including but not limited to magnetic disk storage and optical storage, etc.).
[0041] The present application is described with reference to flowcharts and / or block diagrams according to the method, device (system), and computer program product of the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices produce a machine that implements the flowcharts and / or block diagrams. Figure 1 one flow or multiple flows and / or blocksFigure 1 means for performing the function specified in the block or blocks.
[0042] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the flow Figure 1 flow or flows and / or blocks Figure 1 means for performing the function specified in the block or blocks.
[0043] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the flow Figure 1 flow or flows and / or blocks Figure 1 steps of means for performing the function specified in the block or blocks.
[0044] The above descriptions are only specific embodiments of the application, but the protection scope of the application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the application, which should be covered by the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.
Claims
1. A method for controlling leakage inductance of a planar transformer based on winding sequence, characterized in that, Includes the following steps: Place one turn of the primary coil in the first layer and perform the following determination process: Calculate the magnetic field strength at the end of the preceding winding, and determine the type of the coil placed at the end of the preceding winding based on the magnetic field strength to obtain a temporary winding; wherein, the preceding winding is a winding with a determined arrangement order; calculate the maximum achievable leakage inductance of the temporary winding, compare the maximum achievable leakage inductance of the temporary winding with the preset target leakage inductance, and determine the winding arrangement based on the comparison result; Repeat the determination process until the primary or secondary coil is exhausted. Then, place the remaining coil at the end of the preceding winding to obtain the final winding arrangement.
2. The planar transformer leakage inductance control method based on winding sequence according to claim 1, characterized in that, The step of determining the type of the coil placed at the end of the preceding winding based on the magnetic field strength specifically includes: If the magnetic field strength at the end of the preceding winding is greater than zero, a secondary coil is placed at the end of the preceding winding; if the magnetic field strength at the end of the preceding winding is less than or equal to zero, a primary coil is placed at the end of the preceding winding.
3. The planar transformer leakage inductance control method based on winding sequence according to claim 1, characterized in that, The maximum achievable leakage inductance of the temporary winding is the leakage inductance of the planar transformer obtained by arranging the remaining primary and secondary coils in a completely non-interleaved structure with the temporary winding as the preceding winding. The arrangement is determined according to the magnetic field strength at the end of the preceding winding. When the magnetic field strength at the end of the preceding winding is greater than zero, the primary coil is arranged in front and the secondary coil is arranged behind. When the magnetic field strength at the end of the preceding winding is less than or equal to zero, the primary coil is placed after the secondary coil.
4. The planar transformer leakage inductance control method based on winding sequence according to claim 1, characterized in that, The step of determining the winding arrangement based on the comparison results specifically includes: If the maximum achievable leakage inductance of the temporary winding is greater than or equal to the target leakage inductance, the winding arrangement is the arrangement of the temporary winding. If the maximum achievable leakage inductance of the temporary winding is less than the target leakage inductance, then change the type of the last turn of the temporary winding.
5. A planar transformer, characterized in that, The winding is performed using the final winding arrangement determined by the planar transformer leakage inductance control method based on winding sequence as described in any one of claims 1-4.