Planar winding unit, circuit board and electronic equipment

Abstract

The embodiment of the invention discloses a planar winding unit, a circuit board and electronic equipment, the planar winding unit comprises a magnetic device and a multi-layer PCB, the magnetic device is internally provided with an annular accommodating cavity, one end of a magnetic column formed by a magnet of an inner ring part of the annular accommodating cavity is separated from other magnets, and a gap formed by separation is used as an air gap; a through hole is formed in the multi-layer PCB, the multi-layer PCB is contained in the annular containing cavity, and the magnetic column penetrates through the through hole of the multi-layer PCB; coils are arranged on the multiple layers of PCBs, and the number of turns of the coils on the multiple layers of PCBs is gradually reduced from the end close to the air gap to the end away from the air gap. By adjusting the distribution mode of the number of turns, the number of turns is gradually reduced from one end close to the air gap to one end far away from the air gap under the condition that the total number of turns and the inductance value are not changed, and the influence of the proximity effect of the outer winding far away from the air gap on the winding close to the air gap is reduced, so that the working loss is reduced while the basic design performance is ensured, and the working efficiency is improved. And the effects of improving the efficiency and optimizing the temperature rise are achieved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of planar electronic technology, and in particular to a planar winding unit, a circuit board and an electronic device. Background Art

[0002] In the field of planar electronic devices, in order to reduce the size of the device, the overall size is usually reduced by increasing the wiring density while ensuring the established design goals. However, increasing the wiring density may lead to increased heat loss.

[0003] Taking a planar winding unit with a coil as an example, the coil is usually wound evenly on a multi-layer circuit board, and the number of turns of each layer of the coil is the same. The planar winding unit made in this way will have a relatively large loss during operation due to the proximity effect. Summary of the invention

[0004] The invention provides a planar winding unit, a circuit board and an electronic device to solve the technical problem that the existing planar winding unit has relatively large loss during operation.

[0005] In a first aspect, an embodiment of the present invention provides a planar winding unit, the planar winding unit comprising:

[0006] A magnetic device, wherein an annular accommodating cavity is provided inside the magnetic device, one end of a magnetic column formed by a magnet in an inner ring portion of the annular accommodating cavity is separated from other magnets, and a gap formed by the separation serves as an air gap;

[0007] A multi-layer PCB board, wherein the multi-layer PCB board is provided with a through hole, the multi-layer PCB board is accommodated in the annular accommodation cavity, and the magnetic column passes through the through hole of the multi-layer PCB board;

[0008] Coils are arranged around corresponding through holes on the multi-layer PCB board, and the number of turns of the coils on the multi-layer PCB board gradually decreases from one end close to the air gap to one end far from the air gap.

[0009] In a second aspect, an embodiment of the present invention further provides a circuit board, which includes the planar winding unit of the first aspect.

[0010] In a third aspect, an embodiment of the present invention further provides an electronic device, which includes the planar winding unit of the first aspect.

[0011] In the above-mentioned planar winding unit, circuit board and electronic device, the planar winding unit includes: a magnetic device, an annular accommodating cavity is provided inside the magnetic device, one end of the magnetic column formed by the magnet in the inner ring part of the annular accommodating cavity is separated from other magnets, and the gap formed by the separation is used as an air gap; a multi-layer PCB board, a through hole is provided on the multi-layer PCB board, the multi-layer PCB board is accommodated in the annular accommodating cavity, and the magnetic column passes through the through hole of the multi-layer PCB board; the multi-layer PCB board is provided with coils around the corresponding through holes, and the number of turns of the coils on the multi-layer PCB board gradually decreases from the end close to the air gap to the end far from the air gap. By adjusting the distribution mode of the number of turns, the number of turns is gradually reduced from the end close to the air gap to the end far from the air gap when the total number of turns and the inductance remain unchanged, and the inner layer winding close to the air gap is less affected by the proximity effect of the outer layer winding far from the end of the air gap, so that while ensuring the basic design performance, the loss of the planar winding unit is reduced during operation, thereby improving efficiency and optimizing temperature rise. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of the internal structure of a planar winding unit provided in an embodiment of the present application.

[0013] Figure 2 The figure is a schematic diagram of the internal structure of an existing planar winding unit.

[0014] Figure 3 It is a schematic diagram of current density of an existing planar winding unit.

[0015] Figure 4 The impedance comparison diagram of the coil at different frequencies is a diagram of an inductor coil with the same magnetic core and the same inductance using the planar winding in the embodiment of the present application and the existing planar winding. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0017] It should be noted that the present application specification does not enumerate all optional implementation modes. After reading the present application specification, those skilled in the art should be able to understand that as long as the technical features do not contradict each other, any combination of the technical features can constitute an optional implementation mode.

[0018] The planar winding unit in this scheme is another specific form of the winding unit defined with reference to the winding unit obtained by winding the enameled wire onto the magnetic device to form a multi-turn coil. In the planar winding unit, the coil is not obtained by winding the solid enameled wire, but is processed on the PCB board through the PCB board processing technology. Because the coil made on a processing surface of the PCB board is only a thin layer, the coil can be regarded as existing in a plane, so it is defined as a planar winding unit.

[0019] In the existing planar winding unit, the winding is composed of PCB traces. Figure 2 The planar winding unit 20 shown in the figure is an energy storage inductor, which mainly includes a magnetic device 26, a PCB board arranged in a receiving cavity 261 inside the magnetic device 26, and the PCB board includes an insulating layer 22 and a winding arranged on the insulating layer 22. Figure 2 In the energy storage inductor shown, a first layer of winding 21, a second layer of winding 23 and a third layer of winding 24 are arranged through two layers of PCB boards (the PCB board at one end can be provided with a layer of winding on each of the two board surfaces), and the number of turns of the coils in these three layers of windings is the same. Specifically, each layer may fluctuate slightly in individual products, for example, a difference of one or two turns, but the whole is still centered on the magnetic core 25 in the accommodating cavity 261, and is wound with basically the same number of turns. With the advancement of power supply technology and product iteration, the efficiency and power density of power supplies are required to be higher and higher. Energy storage inductors require higher energy efficiency and lower heat loss. The energy storage inductors in the prior art can no longer meet this requirement. Moreover, not only energy storage inductors, but other planar devices with windings as the core structure have similar problems.

[0020] In response to the above technical problems, this scheme proposes an improved planar winding unit, which adjusts the distribution of the number of turns and gradually reduces the number of turns from the end close to the air gap to the end far away from the air gap while keeping the total number of turns and the inductance unchanged. The inner winding close to the air gap is less affected by the proximity effect of the outer winding far away from the air gap, thereby reducing the loss during operation while ensuring the basic design performance, thereby improving efficiency and optimizing the temperature rise.

[0021] Please refer to Figure 1 , which is a schematic diagram of the internal structure of an exemplary planar winding unit provided in an embodiment of the present application, such as Figure 1As shown, the planar winding unit 10 includes: a magnetic device 16 and a multi-layer PCB board, wherein an annular accommodating cavity 161 is provided inside the magnetic device 16, and one end of a magnetic column 162 formed by a magnet in the inner ring part of the annular accommodating cavity 161 is separated from other magnets, and a gap formed by the separation serves as an air gap 15; a through hole is provided on the multi-layer PCB board, the multi-layer PCB board is accommodated in the annular accommodating cavity 161, and the magnetic column 162 passes through the through hole of the multi-layer PCB board; coils are arranged around corresponding through holes on the multi-layer PCB board, and the number of turns of the coils on the multi-layer PCB board gradually decreases from one end close to the air gap to one end away from the air gap, and each layer of coils corresponds to a winding, Figure 1 The first winding layer 11, the second winding layer 13 and the third winding layer 14 are shown, and the insulating layer 12 on each PCB board realizes the electrical isolation of each winding layer. Specifically for the planar winding unit in different parameter indicators and application scenarios, the number of winding layers and the number of turns of the coil can be adjusted accordingly.

[0022] The magnetic device in the planar winding unit is used for magnetic conduction. Different types of planar winding units use different magnetic devices. For example, the low-frequency winding unit in a general power supply uses iron materials, and the high-frequency winding unit in a high-frequency occasion uses magnetic materials. The functions of different types of planar winding units in the circuit may also be different. For example, the inductor can be used for filtering, energy storage, oscillation and other functions in the circuit. Taking the energy storage function as an example, when the current passes through the coil of the winding in the inductor, a magnetic field is generated around the coil. Due to the magnetic field, the magnetic device gradually magnetizes and stores magnetic energy, thereby playing the role of energy storage. The basic working principle of the planar winding unit is not changed by the adjustment of the details of the structure. The planar winding units in the embodiments of the present application have the same device functions accordingly, and the basic working principle will not be explained in detail here.

[0023] The annular accommodating cavity 161 in the embodiment of the present application is not necessarily obtained by processing a whole piece of raw material used to make the magnetic device 16. It can be a cavity formed by assembling multiple basic structural parts into the magnetic device 16. The present scheme does not limit its specific generation method. It is sufficient for the cavity to accommodate the PCB board.

[0024] The planar winding unit 10 in this solution adjusts the turn distribution mode, and gradually reduces the number of turns from the end close to the air gap 15 to the end far away from the air gap 15 while keeping the total number of turns and the inductance unchanged. The winding close to the air gap 15 is used as the inner winding, and the proximity effect of the outer winding at the end far away from the air gap 15 becomes less affected. Therefore, when the number of turns is the same, the planar winding unit 10 is more stable than the planar winding unit 10. Figure 2 The existing implementation shown, while ensuring the basic design performance indicators, reduces the loss of the planar winding unit 10 during operation, thereby improving efficiency and optimizing temperature rise.

[0025] For specific comparison, please refer to Figure 3 , all coils in each layer of winding are regarded as a thin sheet, and the time-varying current flowing through it is I(t). The time-varying current I(t) generates a time-varying magnetic field H(t), as shown in Figure 3 The coil in the rectangle ABCD corresponds to a thin sheet. A time-varying current I(t) flows through each thin sheet, which generates a time-varying magnetic field H(t). Figure 3 The air gap 25 in the figure is taken as a reference, which can be corresponded to Figure 2 As shown in the third layer winding 24, the magnetic resistance of the magnetic core is very small, and the magnetic resistance on the air gap 25 and the AB line is very large, so that the magnetic field strength on the left side of the third layer winding 24 is almost zero. Due to the magnetic field strength of the time-varying magnetic field H(t) on the right side of the third layer winding 24, the induced current generated by it is outgoing from the right side and incoming from the left side. On the right side of the third layer winding 24, the two current directions are the same, and the induced current and the time-varying current I(t) are superimposed. On the left side of the third layer winding 24, the current directions are opposite, and the induced current and the time-varying current I(t) are offset, resulting in the current of the third layer winding 24 being concentrated on the right side.

[0026] In the middle slice (corresponding to Figure 2 When there is no magnetic field on the left side of the second layer winding 23 (as shown in the figure), the time-varying current I(t) is concentrated on the right side of the second layer winding 23 (refer to the analysis of the third layer winding 24). Since there is a time-varying magnetic field H(t) on the left side of the second layer winding 23, the induced current generated in the second layer winding 23 is from the right side out and from the left side in, that is, the time-varying current I(t) in the third layer winding 24 induces a reverse current -I(t), and the current is concentrated on the left side of the second layer winding 23. Therefore, on the right side of the second layer winding 23, the induced current is superimposed on the time-varying current I(t), and the current flowing through is 2*I(t). The magnetic field intensity on the surface of the second layer winding 23 is 2*H(t). The rightmost sheet (i.e., corresponding to Figure 2 The current and magnetic field strength of the first layer winding 21 shown in FIG. Figure 3 The current density effect shown on the right side of the figure is Figure 3 The three rectangular boxes on the right side of the figure represent the first winding layer 21, the second winding layer 23 and the third winding layer 24 respectively, and each rectangular box specifically presents the current distribution and intensity state confirmed by the full text analysis.

[0027] According to the above analysis, the current of the outer sheet (coil assembly) will induce current on the inner sheet (sheet close to the air gap), causing the current of the inner sheet to be superimposed exponentially, resulting in increased copper loss. In the planar winding unit designed in this scheme, the smaller the number of outer coil currents, the lower the superposition effect, that is, the fewer the number of outer turns, the less the induced current in the inner layer, the smaller the loss of the coil, and the lower the heat generation.

[0028] In terms of the specific method of reducing the number of turns, the number of turns gradually decreases in an arithmetic progression, for example Figure 1 The number of turns of each layer of coils is 9, 7 and 5 from the end close to the air gap 15 to the end far from the air gap 15, and the proximity effect is gradually reduced through uniform changes. Alternatively, the difference between the number of turns of two adjacent layers of windings is an arithmetic progression, for example, the number of turns of each layer of coils is 9, 8, 6, and 3 from the end close to the air gap 15 to the end far from the air gap 15, and the difference between the number of turns of two adjacent layers of windings is getting bigger and bigger, so that more coils are concentrated near the air gap 15, and the planar winding unit 10 is better prevented from generating magnetic saturation during operation. In addition, the surface of the first layer of PCB board close to the end of the air gap 15 can be flush with the air gap 15, so that as many coils as possible are affected by the air gap 15 as much as possible.

[0029] In a specific implementation, the PCB board includes a substrate and a conductive layer, and the coil is obtained by patterning the conductive layer, for example, by etching. In this way, a device as fine as possible is produced, wherein the substrate in the PCB serves as an insulating layer between each layer of windings. The hollow area in the conductive layer can be filled with an insulating material, and the hollow area is a hollow area formed after the conductive layer is patterned. Insulating filling in the hollow area can make up for the break in the patterned conductive layer, and can also avoid bubbles that may be generated in the subsequent production process due to the naturally existing air in the hollow area. The insulating material can be an insulating glue, which can further optimize the insulation, while completely filling the hollow area and discharging the air in the hollow area that may cause bubbles in the subsequent production process. The insulating glue can be a water-resistant and chemical-resistant epoxy glue, thereby providing a certain degree of protection for the planar winding unit during the generation and use process.

[0030] To further illustrate the beneficial effects of the planar winding unit in the embodiment of the present application, the planar winding units of different implementations are simulated to obtain the corresponding equivalent coil impedances at different frequencies. The first implementation is a planar winding unit with uniform distribution in the prior art, with four layers of windings, 11 turns per layer, and a total of 44 turns. The corresponding equivalent coil impedance is recorded as R1 (mohm). The second implementation is a planar winding unit with layered changes in this solution, with Figure 1 From top to bottom, the first to fourth layers are 14 turns, 12 turns, 10 turns and 8 turns, a total of 44 turns, and the corresponding equivalent coil impedance is recorded as R2 (mohm). That is, the total number of coil turns in the first implementation and the second implementation is the same. The planar winding units of the two implementations are simulated at different frequencies to confirm the equivalent coil impedance corresponding to each frequency.

[0031] Frequency(Hz) <![CDATA[R1(mohm)]]> <![CDATA[R2(mohm)]]> Frequency(Hz) <![CDATA[R1(mohm)]]> <![CDATA[R2(mohm)]]> 1e+05 4.53e+03 3.76e+03 1.87e+05 6.45e+03 3.88e+03 1.02e+05 4.56e+03 3.76e+03 1.92e+05 6.57e+03 3.89e+03 1.05e+05 4.6e+03 3.77e+03 1.96e+05 6.71e+03 3.9e+03 1.07e+05 4.64e+03 3.77e+03 2.01e+05 6.85e+03 3.91e+03 1.1e+05 4.68e+03 3.77e+03 2.06e+05 6.99e+03 3.92e+03 1.12e+05 4.73e+03 3.77e+03 2.1e+05 7.15e+03 3.93e+03 1.15e+05 4.77e+03 3.78e+03 2.15e+05 7.31e+03 3.94e+03 1.18e+05 4.82e+03 3.78e+03 2.21e+05 7.47e+03 3.95e+03 1.2e+05 4.87e+03 3.78e+03 2.26e+05 7.65e+03 3.96e+03 1.23e+05 4.93e+03 3.79e+03 2.31e+05 7.83e+03 3.97e+03 1.26e+05 4.98e+03 3.79e+03 2.36e+05 8.83e+03 3.99e+03 1.29e+05 5.04e+03 3.79e+03 2.42e+05 8.23e+03 4e+03 1.32e+05 5.1e+03 3.8e+03 2.48e+05 8.44e+03 4.81e+03 1.35e+05 5.16e+03 3.8e+03 2.54e+05 8.66e+03 4.83e+03 1.38e+05 5.23e+03 3.81e+03 2.6e+05 8.89e+03 4.84e+03 1.42e+05 5.3e+03 3.81e+03 2.66e+05 9.13e+03 4.86e+03 1.45e+05 5.37e+03 3.81e+03 2.72e+05 9.39e+03 4.88e+03 1.48e+05 5.45e+03 3.82e+03 2.78e+05 9.65e+03 4.89e+03 1.52e+05 5.53e+03 3.83e+03 2.85e+05 9.93e+03 4.11e+03 1.56e+05 5.62e+03 3.83e+03 2.92e+05 1.82e+04 4.13e+03 1.59e+05 5.7e+03 3.84e+03 2.98e+05 1.05e+04 4.15e+03 1.63e+05 5.8e+03 3.84e+03 3.05e+05 1.88e+04 4.17e+03 1.67e+05 5.89e+03 3.85e+03 3 13e+05 1.12e+04 4.19e+03 1.71e+05 5.99e+03 3.85e+03 3.2e+05 1.15e+04 4.21e+03 1.75e+05 6.1e+03 3.86e+03 3.27e+05 1.19e+04 4.24e+03 1.79e+05 6.21e+03 3.87e+03 3.35e+05 1.23e+04 4.26e+03 1.83e+05 6.33e+03 3.88e+03 3.43e+05 1.27e+04 4.29e+03

[0032] Table 1

[0033] The equivalent coil impedances of the planar winding units of the two implementation methods simulated at different frequencies are shown in Table 1. For example, when the frequency is 100 KHz, the equivalent coil impedance corresponding to the planar winding unit of the first implementation method (i.e., the planar winding unit implemented in the prior art) is 4.53 ohms, and the equivalent coil impedance corresponding to the planar winding unit of the second implementation method (i.e., the planar winding unit based on the embodiment of the present application) is 3.76 ohms.

[0034] For further comparison of the equivalent coil impedance of the two implementations of the planar winding unit, please refer to Figure 4 , which is a comparison diagram of equivalent coil impedance at different frequencies of the inductor coil with the same magnetic core and the same inductance using the planar winding unit in the embodiment of the present application and the existing planar winding unit, specifically generated based on Table 1. Figure 4 In the figure, curve ① is the curve generated by the equivalent coil impedance corresponding to different frequencies of the planar winding unit of the first implementation, and curve ② is the curve generated by the equivalent coil impedance corresponding to different frequencies of the planar winding unit of the second implementation; by comparing the two curves, it can be found that at the same frequency, the equivalent coil impedance of the planar winding unit of the second implementation is smaller than the equivalent coil impedance of the planar winding unit of the first implementation, and the higher the frequency, the more obvious the advantage of the equivalent coil impedance of the second implementation. The above simulation results can also prove that the planar winding unit in the embodiment of the present application has a significantly lower equivalent coil impedance than the planar winding unit of the prior art, and the corresponding loss during operation is lower, thereby improving efficiency and optimizing temperature rise.

[0035] The planar winding unit in the embodiment of the present application is a planar transformer or a planar inductor. Figure 1 The planar inductor is shown in the figure. The planar winding unit mentioned here refers to a specific electronic device, which may be a type of planar transformer and planar inductor. If the planar winding unit is defined as a type of electronic device, then this type of electronic device includes planar transformers and planar inductors and any other electronic devices that require magnetic devices 16 to cooperate with the winding coil.

[0036] An embodiment of the present invention also provides a circuit board, on which the planar winding unit mentioned above is arranged. The planar winding unit can be installed on the circuit board by welding, screw fixing, etc. The circuit board has corresponding functions and beneficial effects as the planar winding unit mentioned above.

[0037] An embodiment of the present invention also provides an electronic device, on which the planar winding unit mentioned above is arranged. The planar winding unit can be directly installed on the electronic device by welding, screw fixing, etc., or it can be installed on a circuit board by welding, screw fixing, etc., and then the circuit board is installed on the electronic device. Regardless of which method is used, the circuit board and the planar winding unit mentioned above have corresponding functions and beneficial effects.

[0038] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0039] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A planar winding unit, characterized in that: include: A magnetic device, wherein an annular accommodating cavity is provided inside the magnetic device, one end of a magnetic column formed by a magnet in an inner ring portion of the annular accommodating cavity is separated from other magnets, and a gap formed by the separation serves as an air gap; A multi-layer PCB board, wherein the multi-layer PCB board is provided with a through hole, the multi-layer PCB board is accommodated in the annular accommodation cavity, and the magnetic column passes through the through hole of the multi-layer PCB board; The multi-layer PCB boards are all provided with coils around corresponding through holes, and the number of turns of the coils on the multi-layer PCB boards gradually decreases from one end close to the air gap to one end far away from the air gap.

2. The planar winding unit according to claim 1, characterized in that: The number of turns decreases gradually in an arithmetic progression.

3. The planar winding unit according to claim 1, characterized in that: A board surface of the first layer PCB board close to one end of the air gap is flush with the air gap.

4. The planar winding unit according to any one of claims 1 to 3, characterized in that: The PCB board includes a substrate and a conductive layer, and the coil is obtained by patterning the conductive layer.

5. The planar winding unit according to claim 4, characterized in that: The hollow area in the conductive layer is filled with an insulating material, and the hollow area is a hollow area formed after the conductive layer is patterned.

6. The planar winding unit according to claim 5, characterized in that: The insulating material is insulating glue.

7. The planar winding unit according to claim 6, characterized in that: The insulating adhesive is epoxy adhesive.

8. The planar winding unit according to any one of claims 1 to 3, characterized in that: The planar winding unit is a planar transformer or a planar inductor.

9. A circuit board, characterized in that: It comprises the planar winding unit as described in any one of claims 1-8.

10. An electronic device, characterized in that: It comprises the planar winding unit as described in any one of claims 1-8.

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