Power module with planar transformer

Abstract

A power module includes a PCB, a transformer module, and a power converter circuit. The PCB has a top surface and a bottom surface. The transformer module includes a magnetic core, and a primary winding and a secondary winding wound around the magnetic core. The magnetic core has a first magnetic core unit disposed on a top surface of the PCB and a second magnetic core unit disposed on a bottom surface of the PCB. The primary winding is formed by routing on multiple layers of the PCB, the secondary winding is formed by routing on multiple layers of the PCB, and the multiple layers are vertically stacked to form a winding stack. The power converter circuit has power switches, a portion of which is disposed on a top surface of the PCB and another portion of which is disposed on a bottom surface of the PCB.

Description

Technical Field

[0001] The present disclosure generally relates to electronic circuits, and more specifically but not limited to power modules. Background Art

[0002] A power module is used to provide one or more voltages to various electronic devices. The power module may integrate magnetic components, multiple power integrated circuits (ICs), multiple driver ICs, multiple passive devices, etc. In addition, in order to improve the integration degree, the size of the power module needs to be as small as possible. In high-power applications, large currents also pose challenges to the thermal performance of the power module. Therefore, it is desirable to provide a low-cost power module with high power density, high efficiency, and excellent heat dissipation ability in a space-constrained environment. Summary of the Invention

[0003] According to an embodiment of the present disclosure, a power module is provided. The power module includes a printed circuit board (PCB), a transformer module disposed on the PCB, and a power converter circuit. The PCB has a top surface and a bottom surface. The transformer module includes a magnetic core, a primary winding, and a secondary winding wound around the magnetic core. The magnetic core has a first magnetic core unit disposed on the top surface of the PCB and a second magnetic core unit disposed on the bottom surface of the PCB. The primary winding is formed by traces on multiple layers of the PCB, and the secondary winding is formed by traces on multiple layers of the PCB. The multiple layers are vertically stacked to form a winding stack. The power converter circuit has power switches, wherein a part of the power switches is disposed on the top surface of the PCB, and another part of the power switches is disposed on the bottom surface of the PCB.

[0004] According to another embodiment of the present disclosure, a planar transformer module is provided. The planar transformer module includes a PCB, a magnetic core, a winding stack, and a power converter circuit. The PCB has a top surface and a bottom surface. The magnetic core has at least one leg passing through multiple layers of the PCB, a first unit disposed on the top surface of the PCB, and a second unit disposed on the bottom surface of the PCB. The winding stack is formed by traces on multiple layers of the PCB. The winding stack includes a set of primary layers and a set of secondary layers, and the traces are wound around at least one leg of the magnetic core. The power converter circuit includes a primary side circuit and a secondary side circuit. The secondary side circuit includes a rectifier. The magnetic core is disposed between two rectifiers on the top surface of the PCB, and the rectifiers are evenly distributed on the top surface and the bottom surface of the PCB. Brief Description of the Drawings

[0005] The present disclosure can be further understood with reference to the following detailed description and the accompanying drawings, in which the same elements are denoted by the same reference numerals. These drawings are for illustrative purposes only, and thus may only show a part of the devices and are not necessarily drawn to scale.

[0006] Figures 1A - 1C Schematic diagram of a power converter circuit according to some embodiments of the present disclosure.

[0007] Figure 2A Schematic diagram of a power module according to an embodiment of the present disclosure.

[0008] Figure 2B Top view of a power module according to an embodiment of the present disclosure is schematically shown.

[0009] Figure 2C Bottom view of a power module according to an embodiment of the present disclosure is schematically shown.

[0010] Figure 2D Side view of a power module according to an embodiment of the present disclosure.

[0011] Figure 3A Schematic diagram of a magnetic core according to an embodiment of the present disclosure.

[0012] Figure 3B Schematic diagram of a planar transformer module according to an embodiment of the present disclosure.

[0013] Figure 3C Schematic diagram of a planar transformer module according to another embodiment of the present disclosure.

[0014] Figure 4A According to an embodiment of the present disclosure Figure 3A Bottom view of the first magnetic core unit shown.

[0015] Figure 4B According to an embodiment of the present disclosure Figure 3A Side view of the first magnetic core unit shown.

[0016] Figure 5A Schematic diagram of the first magnetic core unit according to an alternative embodiment of the present disclosure.

[0017] Figure 5B Side view of the first magnetic core unit according to an alternative embodiment of the present disclosure.

[0018] Figure 6 The primary winding formed on a layer of the PCB according to an embodiment of the present disclosure is schematically shown.

[0019] Figure 7 The primary winding formed on a layer of the PCB according to another embodiment of the present disclosure is schematically shown.

[0020] Figure 8A Schematic diagram of a winding stack according to an embodiment of the present disclosure is shown.

[0021] Figure 8B FIG. shows a schematic diagram of a winding stack according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0022] Various embodiments of the present disclosure will now be described. In the following description, some specific details are included, such as example circuits and example values of these circuit components, to provide a thorough understanding of the embodiments. However, those skilled in the relevant art will recognize that the present disclosure can be implemented without one or more of the specific details, or by using other methods, components, materials, etc. In other cases, well-known structures, materials, processes, or operations are not shown or described in detail to avoid obscuring aspects of the present disclosure.

[0023] Throughout the specification and claims, the phrases "in one embodiment", "in some embodiments", "in one implementation", and "in some implementations" include combinations and sub-combinations of the various features described herein, as well as variations and modifications thereof. These phrases as used herein do not necessarily refer to the same embodiment, although they may. Those skilled in the art should understand that the meanings of the above terms are not necessarily limiting of these terms, but merely provide illustrative examples of these terms. Note that when an element is "connected to" or "coupled to" another element, this means that the element is directly connected to or coupled to the other element, or indirectly connected to or coupled to the other element via another element. A particular feature, structure, or characteristic may be included in an integrated circuit, an electronic circuit, a combinational logic circuit, or other suitable components that provide the described functionality. Additionally, it should be understood that the drawings provided herein are for the purpose of explanation to those of ordinary skill in the art, and the drawings are not necessarily drawn to scale.

[0024] Figure 1A FIG. is a schematic diagram of a power converter circuit 100 according to an embodiment of the present disclosure. The power converter circuit 100 includes a primary-side circuit 110 and a secondary-side circuit 120, and is configured to convert an input voltage V1 into an output voltage V2. The primary-side circuit 110 includes switching units 112, 114, 116, and 118, a capacitor C1, an inductor L1, and a winding NP. The secondary-side circuit 120 includes rectifiers 122 and 124, a capacitor Co, and windings NS1 and NS2. In this embodiment, the secondary-side circuit 120 includes a center-tapped rectifier circuit. The windings NP, NS1, NS2, and the magnetic core together form a transformer. In some embodiments, the winding NP is referred to as the primary winding, and the windings NS1 and NS2 are referred to as the secondary windings. In one embodiment, the rectifier 122 / 124 is a switching unit. In another implementation, the rectifier 122 / 124 is a diode.

[0025] In Figure 1AIn an embodiment, the primary side circuit 110 includes a full-bridge circuit. In an alternative embodiment, the primary side circuit 110 may include a half-bridge circuit as shown in Figure 1B , a two-phase circuit as shown in Figure 1C , or other similar circuits, and has a configuration different from that shown in Figure 1A .

[0026] In one embodiment, each of the switching units 112, 114, 116, 118, 122, and 124 may include a power switch, such as a Metal–Oxide–Semiconductor Field-Effect Transistor (MOSFET). In some embodiments, one or more of the switching units 112, 114, 116, 118, 122, and 124 may further include a drive circuit (not shown in FIG. 1), and the drive circuit and the corresponding switch are encapsulated together into a single integrated circuit (IC).

[0027] In Figure 1A 's embodiment, the terminals G and g are configured to receive a ground voltage. In various embodiments, the terminals A and B may be coupled to or receive different voltages. In one embodiment, the terminals A and B are coupled to a ground voltage, and the power converter circuit 100 is an isolated LLC resonant converter. In one embodiment, the conversion ratio of the power converter circuit can be expressed as V1 / V2, which is determined by the transformer turns ratio (i.e., the number of turns N1 of the primary winding NP and the number of turns N2 of the secondary windings NS1 / NS2). For example, for a full-bridge LLC converter, the transformer turns ratio N1:N2 = 8:1, and when the input voltage is 48V, the output voltage is 6V.

[0028] In an alternative embodiment, the power converter circuit 100 is a non-isolated LLC resonant converter, and the terminals A and B are not coupled to a ground voltage. For example, terminal A is coupled to terminal 3, and terminal B is coupled to terminal 1. In this embodiment, assuming the conversion ratio V1 / V2 of the power converter circuit is 8:1, the transformer turns ratio N1:N2 = 6:1.

[0029] In another example, both terminals A and B are coupled to terminal 2. In this embodiment, assuming the conversion ratio V1 / V2 of the power converter circuit is 8:1, the transformer turns ratio N1:N2 = 7:1.

[0030] In yet another example, terminal A is coupled to terminal 1, and terminal B is coupled to terminal 3. In this embodiment, assuming the conversion ratio V1 / V2 of the power converter circuit is 8:1, the transformer turns ratio N1:N2 = 8:1.

[0031] In some embodiments, the power converter circuit 100 is implemented as a power module 200. Figure 2A Schematic diagram of the power module 200 according to an embodiment of the present disclosure. Figure 2B A top view (e.g., the top surface of the PCB 210) of the power module 200 according to an embodiment of the present disclosure is schematically shown. Figure 2C A bottom view (e.g., the bottom surface of the PCB 210) of the power module 200 according to an embodiment of the present disclosure is schematically shown. Figure 2D Side view of the power module 200 according to an embodiment of the present disclosure.

[0032] As Figures 2A - 2D shown, the power module 200 includes a printed circuit board (PCB) 210, a primary side switch 220, a secondary side switch 230, a transformer module 240, and other electronic components, such as capacitors. In some embodiments, the primary side switch 220 corresponds to Figure 1A the switches in the switch units 112, 114, 116, 118 in the embodiment of Figure 1A , the secondary side switch 230 corresponds to Figure 1A the switches in the switch units 122 and 124 in the embodiment of

[0033] In one embodiment, the primary side switch 220 is disposed on the top surface of the PCB 210, as Figure 2B shown. In one embodiment, the rectifier 230 is disposed on the top surface of the PCB 210 (as Figure 2B shown) and on the bottom surface of the PCB 210 (as Figure 2C shown). In one embodiment, the rectifier 230 is evenly distributed on the top and bottom surfaces of the PCB 210. For example, as Figure 2B shown, there are 2 rectifiers 230 disposed on the top surface of the PCB 210, and as Figure 2C shown, there are 2 rectifiers 230 disposed on the bottom surface of the PCB 210.

[0034] In one embodiment, the transformer module 240 is arranged between two rectifiers 230 on the top surface of the PCB 210, as Figure 2B shown. In one embodiment, the transformer module 240 is arranged between two rectifiers 230 on the bottom surface of the PCB 210, as Figure 2C shown. In some embodiments, the output capacitor Co is disposed adjacent to the rectifier 230. In one embodiment, the rectifier 230 is arranged between the output capacitors Co.

[0035] In some embodiments, as Figures 2A - 2D shown, the transformer module 240 is arranged between two secondary-side switches 230 in the X direction. The output capacitor (e.g., the capacitor Co as Figure 1A shown) is arranged adjacent to the secondary-side switch 230 in the Y direction.

[0036] In some embodiments, the transformer module 240 includes a planar transformer. The planar transformer has a magnetic core and windings (e.g., windings NP, NS1, NS2) wound around the leg parts of the magnetic core. The windings are formed in a spiral shape on a printed circuit board (PCB) (such as the windings W1 - W4 as Figures 6 - 7 shown). Figure 3A FIG. is a schematic diagram of a magnetic core 300 according to an embodiment of the present disclosure. In some embodiments, Figures 2A - 2D the transformer module 240 in Figure 3A includes the magnetic core 300. As

[0037] Figure 3B shown, the magnetic core 300 includes a first magnetic core unit 310 and a second magnetic core unit 320, and the first magnetic core unit 310 includes two legs. In some embodiments, the first magnetic core unit 310 is referred to as a U-shaped magnetic core. Specifically, the U-shaped magnetic core has two legs 312 and 314 and a connecting part 316 connecting the two legs 312 and 314. In some embodiments, the second magnetic core unit 320 is referred to as an I-shaped magnetic core. Figure 3B FIG. is a schematic diagram of a planar transformer module 30 according to an embodiment of the present disclosure. The magnetic core 300 has at least one leg (e.g., 312, 314) passing through multiple layers of the PCB, a first unit 316 arranged on the top surface of the PCB, and a second magnetic core unit 320 arranged on the bottom surface of the PCB. As

[0038] Figure 3C shown, the two legs of the first magnetic core unit 310 extend through the PCB 210, and the first magnetic core unit 310 is arranged on the second magnetic core unit 320. Figure 3C FIG. is a schematic diagram of a planar transformer module 32 according to another embodiment of the present disclosure. In the

[0039] embodiment of Figure 3BIn the embodiment, the first magnetic core unit 310 is attached to the PCB 210, and there is a gap 382 between the PCB 210 and the second magnetic core unit 320. Similarly, as Figure 3C shown, the first magnetic core unit 310 is attached to the PCB 210, and there is a gap 384 between the PCB 210 and the first magnetic core unit 310. Compared with Figure 3C the embodiment, since Figure 3B in the embodiment, the first unit 316 is attached to the top surface of the PCB 210 and there is no gap on the top surface of the PCB 210, the planar transformer module 32 can withstand higher pressure from the heat sink on the magnetic core 300 placed above the top surface of the PCB 210.

[0040] Figure 4A is a bottom view of the first magnetic core unit 310 shown according to an embodiment of the present disclosure. Figure 3A shown. Figure 4B is a side view of the first magnetic core unit 310 shown according to an embodiment of the present disclosure. As Figure 3A shown, the first magnetic core unit 310 has two legs 420 and a connecting portion 410 connecting the two legs 420. The connecting portion 410 has a thickness T1. Figures 4A - 4B shown.

[0041] Figure 5A is a schematic diagram of the first magnetic core unit 500 according to an alternative embodiment of the present disclosure. Figure 5B is a side view of the first magnetic core unit 500 according to an alternative embodiment of the present disclosure. In some embodiments, as Figure 3A shown, the first magnetic core unit 310 is replaced by the first magnetic core unit 500. In other words, the first magnetic core unit 500 and the second magnetic core unit 320 together form the magnetic core of the transformer module.

[0042] As Figures 5A - 5B shown, the first magnetic core unit 500 has two legs 520 and a connecting portion 516 connected to the two legs 520. Compared with the connecting portion 410 of the first magnetic core unit 310 as Figures 4A - 4B shown, the first magnetic core unit 500 further includes a side portion 518 connected to the connecting portion 516, and the side portion 518 is arranged parallel to the two legs 520. Specifically, as Figure 5BAs shown, the side portion 518 is a portion extending in the Z-axis direction, while the connecting portion 410 only has a portion extending in the Y-axis direction. Therefore, when the first magnetic core unit 500 is coupled to the second magnetic core unit 310, since the magnetic flux can be transmitted to the second magnetic core unit 310 through the side portion 518 of the first magnetic core unit 500 that extends along the Z direction, the connecting portion 516 of the first magnetic core unit 500 that extends along the Y direction has a smaller thickness T2. That is to say, the thickness T2 of the connecting portion 516 is less than the thickness T1 of the connecting portion 410.

[0043] In one embodiment, Figure 2A the PCB 210 shown is a multi-layer PCB. The transformer module includes a primary winding and a secondary winding wound around a magnetic core (e.g., the legs 312 and 314 as Figure 3B shown). Specifically, the primary winding and the secondary winding are formed by traces on multiple layers of the PCB, and these multiple layers are vertically stacked to form a winding stack. Figure 6 Schematically shows a primary winding formed on a layer 600 of the PCB according to an embodiment of the present disclosure. As Figure 6 shown, the traces of the primary winding on a layer 600 of the PCB form a spiral pattern. Specifically, the spiral pattern has multiple turns. For example, the winding W1 winds two turns around one of the legs 620, and the winding W2 winds two turns around the other leg of the legs 620. Each of the windings W1 and W2 has a first turn 611 and a second turn 612. The first turn 611 has a width D1, the second turn 612 has a width D2, and the width D1 is less than the width D2.

[0044] Figure 7 Is a primary winding formed on a layer 700 of the PCB according to another embodiment of the present disclosure. As Figure 7 shown, the winding W3 is wound around one of the legs 720, and the winding W4 is wound around the other leg of the legs 720. Each of the windings W3 and W4 has a first turn 711, a second turn 712, and a third turn 713. The first turn 711 has a width D3, the second turn 712 has a width D4, and the third turn 713 has a width D5. The width D3 is less than the width D4, and the width D4 is less than the width D5.

[0045] In some embodiments, the primary winding of the transformer (e.g., the winding NP shown in FIG. 1) has a configuration as Figure 6 or Figure 7 shown. In the embodiments of Figure 6 and Figure 7 , from the inner circle to the outer circle, the width of the winding gradually increases in order to reduce the total winding loss of the transformer. In some embodiments, the width of each turn is predetermined so that each turn has substantially the same winding loss.

[0046] As described above, the transformer module 240 is a planar transformer, including a set of primary layers NP and a set of secondary layers. Specifically, the secondary layers further include a set of first secondary layers NS1 and a set of second secondary layers NS2. In one embodiment, the primary winding and the secondary windings (NP, NS1, NS2) are formed on different layers of the PCB, and these layers of the PCB can be stacked vertically (e.g., along the Z direction) in the order shown in Table 1 below to form a winding stack.

[0047] L1 NS1 L2 NP L3 NS2 L4 NS2 L5 NP L6 NS1 L7 …

[0048] Table 1

[0049] As shown in Table 1, the first layer L1 is the winding NS1, the second layer L2 is the winding NP, the third layer L3 is the winding NS2, the fourth layer L4 is the winding NS2, the fifth layer L5 is the winding NP, the sixth layer L1 is the winding NS1, and so on. The primary layer NP is located between the first secondary layer NS1 and the second secondary layer NS2. In other words, each winding NP is sandwiched between the winding NS1 and the winding NS2.

[0050] Specifically, Figure 8A A schematic diagram of a winding stack formed on a multi-layer PCB is shown, with traces of the primary / secondary windings on each layer of the PCB. As Figure 8A shown, the winding stack includes a set of primary layers (e.g., NP1 and NP2), a set of first secondary layers (e.g., NS1), and a set of second secondary layers (e.g., NS2). For example, the primary layers include PCB layers L4, L7, L10, and L13, the first secondary layers include PCB layers L3, L8, L9, and L14, and the second secondary layers include PCB layers L5, L6, L11, and L12.

[0051] In an alternative embodiment, the windings NP, NS1, NS2 are formed on different layers of the PCB, and these layers of the PCB can be stacked vertically (e.g., along the Z direction) in the order shown in Table 2 below.

[0052] L1 NP L2 NS1 L3 NP L4 NS2 L5 NP L6 NS1 L7 …

[0053] Table 2

[0054] As shown in Table 2, the first layer L1 is the winding NP, the second layer L2 is the winding NS1, the third layer L3 is the winding NP, the fourth layer L4 is the winding NS2, the fifth layer L5 is the winding NP, the sixth layer L1 is the winding NS1, and so on. In other words, after each winding NP is the winding NS1 or the winding NS2, and the number of layers of the winding NP is greater than the number of layers of the winding NS1 or NS2.

[0055] Figure 8BShows a schematic diagram of a winding stack according to another embodiment. As Figure 8B shown, the winding stack includes a set of primary layers (e.g., NP1 and NP2), a set of first secondary layers (e.g., NS1), and a set of second secondary layers (e.g., NS2). For example, the primary layers include PCB layers L2, L4, L6, L8, L10, L12, and L14, the first secondary layers include PCB layers L3, L7, L11, and L15, and the second secondary layers include PCB layers L5, L9, and L13.

[0056] In some embodiments, when the layers of windings NP, NS1, NS2 are stacked in the order shown in Table 1 or Table 2, the current distribution in each layer of the PCB becomes uniform, and heat dissipation can be improved.

[0057] Thus, the present disclosure provides a power module having a switch and a driver circuit packaged together. In some embodiments, the number of ICs arranged on the power module can be equal to or less than 11. Additionally, due to the arrangement of the transformer module, secondary switch, and output capacitor, the power module can have a smaller placement area. Further, due to the different widths of the primary windings and the different order of the stacked PCB layers, the windings of the transformer can have a uniform current distribution, improved heat dissipation performance, and increased efficiency.

[0058] Those skilled in the art should understand that the present disclosure is not limited to what has been particularly shown and described above. Instead, the scope of the present disclosure is defined by the claims and includes combinations and sub - combinations of the various features described above, as well as variations and modifications that would occur to those skilled in the art after reading the foregoing description and are not in the prior art.

Claims

1. A power module, comprising: a printed circuit board (PCB) having a top surface and a bottom surface; The transformer module is arranged on the PCB and includes: A magnetic core having a first magnetic core unit arranged on the top surface of the PCB and a second magnetic core unit arranged on the bottom surface of the PCB; a primary winding wound on the magnetic core; and A secondary winding, wound on the magnetic core; wherein the primary winding is formed by multiple layers of routing of the PCB, the secondary winding is formed by multiple layers of routing of the PCB, and the multiple layers are vertically stacked to form a winding stack; and A power converter circuit includes a plurality of power switches, wherein a portion of the plurality of power switches is disposed on a top surface of the PCB, and another portion of the plurality of power switches is disposed on a bottom surface of the PCB.

2. The power module according to claim 1, wherein: The first magnetic core unit is an I-shaped magnetic core.

3. The power module according to claim 1, wherein: The first core unit is a U-shaped core including two legs and a connection portion connected to the two legs.

4. The power module according to claim 3, wherein: The first magnetic core unit also includes: A side portion connected to the connecting portion, wherein the side portion is arranged parallel to the two feet.

5. The power module according to claim 1, wherein: A transformer turns ratio of the transformer module is configured to provide a conversion ratio of the power converter circuit.

6. The power module according to claim 1, wherein: The routing of the primary winding forms a spiral pattern on one layer of the PCB, the spiral pattern having a plurality of turns, and wherein a width of a first turn of the spiral pattern is different from a width of a second turn of the spiral pattern.

7. The power module according to claim 1, wherein: The winding stack comprises a set of primary layers, a set of first secondary layers and a set of second secondary layers, wherein the primary layers are located between the first secondary layers and the second secondary layers.

8. The power module according to claim 1, wherein: The power converter circuit includes a primary side circuit and a secondary side circuit, wherein the primary side circuit includes a plurality of primary side switches disposed on a top surface of the PCB.

9. The power module according to claim 1, wherein: The power converter circuit includes a primary side circuit and a secondary side circuit, and the secondary side circuit includes a plurality of rectifiers disposed on a top surface of the PCB and a bottom surface of the PCB.

10. The power module according to claim 9, wherein: The transformer module is arranged between two rectifiers on the top surface of the PCB.

11. The power module according to claim 9, wherein: The secondary side circuit also includes a plurality of output capacitors, and the output capacitors are arranged adjacent to the rectifier.

12. The power module according to claim 1, wherein: The power converter circuit includes a primary side circuit and a secondary side circuit, and the primary side circuit includes a full bridge circuit.

13. The power module according to claim 1, wherein: The power converter circuit includes a primary side circuit and a secondary side circuit, and the secondary side circuit includes a center-tapped rectifier circuit.

14. The power module according to claim 1, wherein: The power converter circuit and the transformer module form an LLC converter.

15. The power module according to claim 1, wherein: The power converter circuit and the transformer module form a non-isolated LLC converter.

16. The power module according to claim 1, wherein: A driver circuit and one of the power switches are integrated in an IC.

17. A planar transformer module, comprising: a printed circuit board (PCB) having a top surface and a bottom surface; A magnetic core having at least one leg passing through multiple layers of the PCB, a first unit arranged on a top surface of the PCB, and a second unit arranged on a bottom surface of the PCB; a winding stack formed by traces on multiple layers of the PCB, wherein the winding stack includes a set of primary layers and a set of secondary layers, and the traces are wound around the at least one leg of the magnetic core; and A power converter circuit comprises a primary side circuit and a secondary side circuit, wherein the secondary side circuit comprises a plurality of rectifiers, wherein the magnetic core is arranged between two rectifiers on the top surface of the PCB, and the rectifiers are evenly distributed on the top and bottom surfaces of the PCB.

18. The planar transformer module according to claim 17, wherein: The traces on the primary layer form a spiral pattern having a plurality of turns, and wherein a width of a first turn of the spiral pattern is different from a width of a second turn of the spiral pattern.

19. The planar transformer module according to claim 17, wherein: The secondary layers include a set of first secondary layers and a set of second secondary layers, wherein the primary layer is located between the first secondary layers and the second secondary layers.

20. The planar transformer module according to claim 17, wherein: The primary side circuit includes a plurality of primary side switches disposed on a top surface of the PCB.

21. The planar transformer module according to claim 17, wherein: The secondary side circuit further includes a plurality of output capacitors, and the rectifier is arranged between the plurality of output capacitors.

22. The planar transformer module according to claim 17, wherein: The power converter circuit includes a primary side circuit and a secondary side circuit, and the primary side circuit includes a full-bridge circuit and the secondary side circuit includes a center-tapped rectifier circuit.

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