Resonant converter

Abstract

A resonant converter comprises a first circuit board, a second circuit board and a flat plate type transformer, and the flat plate type transformer comprises an iron core, a plurality of wires and a first conductive column. A first iron core column of the iron core penetrates through a first circuit board through hole of the first circuit board and a second circuit board through hole of the second circuit board. The wires are respectively formed around the first circuit board through hole and the second circuit board through hole, and the first conductive columns are electrically connected with the wires to form a winding of the flat plate type transformer. The first filling hole is used for electrically connecting an electric element and a winding embedded into any sub-layer plate of the first circuit board or the second circuit board, and the iron core is used for sleeving the winding to form the flat plate type transformer.

Description

Technical Field

[0001] The present invention relates to a resonant converter, and in particular to a resonant converter using a planar transformer. Background Art

[0002] With the rapid development of the information industry, power supplies have played an indispensable role. The input voltage of information and household appliances is divided into AC voltage and DC voltage, and power supplies can generally be divided into two levels. Generally, the front stage is usually an AC / DC converter, a power factor corrector or a DC / DC converter, and the back stage is usually a resonant converter. The resonant converter is a DC-to-DC power converter that can be set to operate in zero voltage switching (Zero Voltage Switching) of the primary side switch and zero current switching (Zero Current Switching) of the secondary side rectifier switch. Therefore, compared with other converters, it has the advantages of high output power and high conversion efficiency. Further, the use of synchronous rectification switches on the secondary side makes it easier to achieve high efficiency and high power density performance.

[0003] Further, as follows Figure 1 This diagram illustrates the internal circuitry of a conventional power supply. The power supply unit (PSU) includes an input circuit CT_I, a power factor corrector (PFC), an auxiliary power circuit AUX, a DC bus capacitor Cap_B, a resonant converter 100, a control circuit MCU, and an output circuit CT_O. The PSU may also optionally include a fan for heat dissipation during operation. The input circuit CT_I receives AC power, performs power factor correction (PFC) on the power factor corrector (PFC), and converts the AC power into DC power, which is then stored in the DC bus capacitor Cap_B. The auxiliary power circuit AUX converts the DC power into auxiliary power to power various components of the PSU that require small amounts of DC power, such as, but not limited to, the controllers, drivers, fans, and LEDs of the converters. The resonant converter 100 converts the DC power into output power and provides this power to a connected load (e.g., a server) via the output circuit CT_O. The control circuit MCU is used to communicate with the load through the output circuit CT_O, and control the power supply PSU based on the communication result.

[0004] In conventional technology, a resonant converter typically includes multiple power components (such as power switches, output capacitors, and drivers), a resonant inductor, and a transformer. These components are typically mounted on a circuit board, with wiring software used to connect them. Because the resonant converter's transformer uses planar technology, the transformer is formed on a single circuit board. When current flows through it, the circuit board must withstand high currents, potentially leading to excessive heat accumulation and inefficient heat dissipation.

[0005] Due to obstructions from components such as power elements, resonant inductors, and transformers, trace routing must bypass these components and their solder joints (pads). This increases trace length and wiring difficulty, making it impossible to reduce the resonant converter's AC impedance and line losses, hindering further efficiency improvements. Summary of the Invention

[0006] Therefore, how to design a resonant converter to solve the problems and technical bottlenecks in the prior art has become an important topic studied by the inventors of this case.

[0007] To address the aforementioned issues, the resonant converter disclosed herein includes a first circuit board, a second circuit board, a primary-side circuit, a secondary-side circuit, and a planar transformer. The planar transformer includes a first circuit board through-hole, a second circuit board through-hole, an iron core, multiple traces, a first conductive post, and a first via. The first and second circuit boards each include multiple sub-layer boards, and the primary circuit is disposed on the first circuit board. The secondary-side circuit is disposed on the first and second circuit boards, respectively, and either the primary circuit or the secondary circuit includes a power component. The power component is embedded in any of the sub-layer boards, and the planar transformer is disposed on the first and second circuit boards. The planar transformer electrically connects the primary circuit and the secondary circuit, and the first and second circuit board through-holes extend through the first and second circuit boards, respectively. The iron core includes a first iron core post extending through the first and second circuit board through-holes, and traces are formed around the first and second circuit board through-holes, respectively. The first conductive post is disposed between the first and second circuit boards and electrically connects the traces disposed around the first circuit board through-hole with the traces disposed around the second circuit board through-hole, thereby forming the windings of the planar transformer. The first vias are formed on the first circuit board or the second circuit board and are used to electrically connect the power components and windings disposed on any sub-layer board. The iron core is used to sheath the windings of the first circuit board and the second circuit board to form a flat-plate transformer.

[0008] To address the aforementioned issues, the resonant converter disclosed herein includes a first circuit board, a second circuit board, a primary-side circuit, a secondary-side circuit, and a planar transformer. The planar transformer includes a first circuit board through-hole, a second circuit board through-hole, an iron core, a primary-side trace, a secondary-side trace, and a first conductive post. The first and second circuit boards each include multiple sub-layer boards, and the primary-side circuit is disposed on the first circuit board. The secondary-side circuit is disposed on the first and second circuit boards, respectively, and each includes a first switch, a second switch, and an output capacitor. The output capacitor is electrically connected to the first and second switches, and the planar transformer is disposed on the first and second circuit boards. The planar transformer electrically connects the first and second switches, and the output capacitor, of the first and second circuit boards. The first and second circuit board through-holes extend through the first and second circuit boards, respectively. The iron core includes a first iron core post extending through the first and second circuit board through-holes, and the primary-side trace is disposed on the first and second circuit boards. The secondary-side trace is disposed on the first and second circuit boards, respectively, and formed around the first and second circuit board through-holes. One end of the secondary-side trace is electrically connected to the first switches of the first circuit board and the second circuit board, respectively, and the other end of the secondary-side trace is electrically connected to the second switches of the first circuit board and the second circuit board, respectively. A first conductive column is disposed between the first circuit board and the second circuit board and electrically connects the primary-side traces of the first circuit board and the second circuit board. The iron core is used to sheath the primary-side traces and the secondary-side traces of the first circuit board and the second circuit board to form a flat-plate transformer. The first switch of the first circuit board is disposed on the same side of the through-hole of the first circuit board, and the output capacitor of the first circuit board is configured between the first switch and the second switch of the first circuit board. The first switch of the second circuit board is disposed on the same side of the through-hole of the second circuit board, and the output capacitor of the second circuit board is configured between the first switch and the second switch of the second circuit board.

[0009] One purpose and effect of the present disclosure is that the resonant converter of the present disclosure utilizes a two-circuit-circuit-circuit-type physical structure, with a single iron core sheathed with a winding formed by conductive posts electrically connecting the two circuit board traces, resulting in a four-sided structure. Furthermore, the power components in the power path of the resonant converter can be embedded into any sub-layer of the circuit board using embedding technology. This minimizes the AC impedance of the resonant converter, thereby improving circuit efficiency, and evenly distributes heat to effectively increase the heat dissipation area, thereby improving circuit efficiency.

[0010] Another disclosed purpose and effect is that the resonant converter of the present disclosure utilizes a two-circuit-circuit-circuit-type physical structure, with a single iron core housing a winding formed by conductive posts electrically connecting the two circuit board traces, resulting in a four-sided structure. Furthermore, the component arrangement structure of the secondary-side circuit of the resonant converter enables a circular current path to be formed when the first switch or the second switch is turned on. This provides the shortest current path, reduces path loss, and evenly distributes heat, effectively increasing the heat dissipation area and thereby improving circuit efficiency.

[0011] In order to further understand the techniques, means and effects adopted by the present invention to achieve the intended objectives, please refer to the following detailed description of the present invention and the accompanying drawings. It is believed that the objectives, features and characteristics of the present invention can be further understood in detail. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of the internal circuit arrangement of a conventional power supply;

[0013] Figure 2 A schematic diagram of the internal circuit configuration of the power supply of the present disclosure in combination with the integrated power conversion module of the present disclosure;

[0014] Figure 3A is a circuit diagram of a first embodiment of a resonant converter disclosed herein;

[0015] Figure 3B is a circuit diagram of a second embodiment of a resonant converter disclosed herein;

[0016] Figure 3C is a circuit diagram of a third embodiment of a resonant converter disclosed herein;

[0017] Figure 4A A first perspective view of the three-dimensional circuit structure assembly of the second embodiment of the resonant converter disclosed herein;

[0018] Figure 4B A second perspective view of the three-dimensional circuit structure assembly of the second embodiment of the resonant converter disclosed herein;

[0019] Figure 4C A third perspective view of the three-dimensional circuit structure assembly of the second embodiment of the resonant converter disclosed herein;

[0020] Figure 4D This is an exploded view of the three-dimensional circuit structure of the second embodiment of the resonant converter disclosed herein;

[0021] Figure 5A A wiring structure diagram of one surface layer of the first circuit board of the second embodiment;

[0022] Figure 5B A wiring structure diagram of another surface layer of the first circuit board of the second embodiment;

[0023] Figure 6A A wiring structure diagram of one surface layer of the second circuit board of the second embodiment;

[0024] Figure 6B A wiring structure diagram of another surface layer of the second circuit board of the second embodiment;

[0025] Figures 7A to 7H Schematic diagrams of the wiring of the windings of the flat-plate transformer of the present disclosure on the first circuit board and each sub-layer board of the second embodiment;

[0026] Figures 8A to 8H Schematic diagrams of the wiring of the windings of the flat-plate transformer of the present disclosure on the second circuit board of the second embodiment and on each sub-layer board;

[0027] Figure 9A For this disclosure Figures 7A to 7H The planar transformer of the second embodiment is stacked on each sub-layer of the first circuit board, and the magnetomotive force curve diagram when the first circuit board is in operation on the first secondary side; and

[0028] Figure 9B For this disclosure Figures 8A to 8H A magnetomotive force curve diagram of the planar transformer on the second embodiment of the second circuit board with the wiring stacking structure of each sub-layer board, and the second circuit board when operating on the first secondary side wiring;

[0029] Figure 10A A cross-sectional view of a circuit board using embedding technology for the power components of the resonant converter of the present disclosure;

[0030] Figure 10B A top view of a circuit board using embedding technology for the power components of the resonant converter of the present disclosure;

[0031] Figure 10C A circuit diagram showing a configuration in which the power element on the secondary side of the resonant converter disclosed herein is embedded into a surface layer of a circuit board using an embedded technology;

[0032] Figure 10D A circuit configuration diagram showing a power element on the secondary side of the resonant converter disclosed herein being embedded into another surface layer of a circuit board using embedded technology;

[0033] Figure 10E A top view and a cross-sectional view of a circuit board according to a first embodiment of the present disclosure using an embedding technique for routing the planar transformer;

[0034] Figure 10FA top view and a cross-sectional view of a circuit board of a second embodiment of the present disclosure using an embedding technique for routing the planar transformer;

[0035] Figure 10G A side view of a circuit board using embedded technology for routing the power components and planar transformers disclosed herein;

[0036] Figure 11A A diagram showing the arrangement of components of a secondary side circuit of a resonant converter of the present disclosure; and

[0037] Figure 11B 1 is a diagram illustrating component arrangements of the resonant converter according to different secondary-side circuit structures.

[0038] The reference numerals are as follows:

[0039] PSU: Power Supply Unit

[0040] CT_I: Input circuit

[0041] IN_AC: power input terminal

[0042] EMI: Electromagnetic Interference Filter

[0043] PFC: Power Factor Corrector

[0044] Cap_B: DC bus capacitor

[0045] CM_I: Integrated power conversion module

[0046] MCU: system control circuit

[0047] AUX: Auxiliary power circuit

[0048] CT_O: output circuit

[0049] Fan: fan

[0050] SE: Space

[0051] 100: Resonant Converter

[0052] 100A: Resonant conversion circuit

[0053] CB, CB1, CB2: circuit boards

[0054] Via_A~B、Via_HD:filling holes

[0055] LA, LA1-1~LA1-8, LA2-1~LA2-8: sub-layer board

[0056] IN: Input terminal

[0057] OUT: output terminal

[0058] SG:Signal transmission end

[0059] 1A: Primary side circuit

[0060] SP_1: Primary side switch bridge arm

[0061] Q1, Q2: power switches

[0062] Lr: resonant inductor

[0063] CL: Inductor core

[0064] HL1, HL2: Inductor perforation

[0065] Lc: Inductor winding

[0066] Tl-1, Tl-2: Inductor routing

[0067] Cr: resonant capacitor

[0068] 2A, 2B: Transformer

[0069] PE: Flat type transformer

[0070] CB1_H: First circuit board perforation

[0071] CB2_H: Second circuit board through hole

[0072] H1, H2, H3, H4, H: Perforated

[0073] C1, C2: iron core

[0074] C1_1, C1_2, CL_1, CL_2: Cover

[0075] C1_3, CL_3: side

[0076] C1_4, CL_4: accommodating groove

[0077] C12: First core column

[0078] C14: Second core column

[0079] GP: Air Gap

[0080] 22: Winding

[0081] T_1(n)~T_3(n), T_1(m)~T_3(m), Tc, Tc_1, Tc_2: routing DW_1, DW_2: extension direction

[0082] AR: Area 22A: Primary side winding

[0083] Tp-1, Tp-2: primary side wiring

[0084] 22B: Secondary winding

[0085] Ts-1, Ts-2, Ts-1_1~Ts-1_n: Secondary side wiring

[0086] 22B-1: First winding

[0087] Ts1-1, Ts1-2, Ts1-1_(n), Ts1-2_(m): first secondary side trace 22B-2: second winding

[0088] Ts2-1, Ts2-2, Ts2-1_(n), Ts2-2_(m): Secondary side traces PC_1, PC_2: Conductive posts

[0089] PC: Pillar

[0090] MMF: Magnetomotive force

[0091] M0: magnetic flux origin

[0092] M1: first predetermined offset

[0093] Mr: second predetermined offset

[0094] F_D1: first direction flux

[0095] F_D2: Second direction magnetic flux

[0096] CF1, CF2: magnetomotive force curves

[0097] 3A: Secondary side circuit

[0098] 32: Rectifier circuit

[0099] SS_1, SS_2: Secondary side switch bridge arms

[0100] SR1, SR2, SR3, SR4: switches

[0101] Co: output capacitance

[0102] 4A, IC_SR: controller

[0103] DC / DC: DC conversion circuit

[0104] 300: Load

[0105] 400: Power components

[0106] AR_H: Hollow area

[0107] Pad, Pad_1, Pad_2: contacts

[0108] Ce:Electronic components

[0109] WM: Modular Winding

[0110] MC: Conductive material

[0111] Pac: AC power supply

[0112] Pdc: DC power supply

[0113] Po: output power

[0114] Paux: Auxiliary power

[0115] I1, I2: current

[0116] Li, Li_1, Li_2: current path DETAILED DESCRIPTION

[0117] The technical content and detailed description of the present invention are now described as follows with reference to the accompanying drawings:

[0118] See also Figure 2 The power supply PSU is a schematic diagram of the internal circuit configuration of the disclosed power supply in conjunction with the disclosed integrated power conversion module. The power supply PSU includes an input circuit CT_I, a power factor corrector PFC, a DC bus capacitor Cap_B, an integrated power conversion module CM_I, and an output circuit CT_O. The power supply PSU may also optionally include a fan Fan for heat dissipation during operation. The input circuit CT_I includes a power input terminal IN_AC and an electromagnetic interference filter EMI. The integrated power conversion module CM_I includes a resonant converter 100, a system control circuit MCU, and an auxiliary power circuit AUX. The power supply PSU receives AC power Pac from the power input terminal IN_AC of the input circuit CT_I. After filtering by the electromagnetic interference filter EMI and power factor correction by the power factor corrector PFC, the converted DC power Pdc is converted to DC power Pdc. The converted DC power Pdc is then stored in the DC bus capacitor Cap_B. The DC power Pdc is converted to output power Po by the resonant converter 100 and provided to critical loads (not shown) in the back-end system via the output circuit CT_O. The DC power supply Pdc can also be converted into auxiliary power supply Paux via the auxiliary power circuit AUX. In addition to being provided to non-critical loads (not shown) of the backend system via the output circuit CT_O, it can also be provided internally to peripheral devices such as fans.

[0119] In one embodiment, the system control circuit MCU includes multiple controllers (not shown), each of which can control internal circuits of the power supply (PSU), such as the power factor corrector (PFC), the resonant converter 100, and the auxiliary power circuit AUX. It can also control communication between the power supply (PSU) and external devices (e.g., back-end systems). In another embodiment, the present disclosure integrates the auxiliary power circuit AUX, the resonant converter 100, and the system control circuit MCU into an integrated power conversion module CM_I. This eliminates significant wiring space, at least eliminating space SE (indicated by dashed lines) for the power supply (PSU).

[0120] See also Figure 3A to Figure 3C The circuit diagrams of the first to third embodiments of the resonant converter disclosed in the present invention are shown in FIG. Figures 1 and 2 . The resonant converter 100 receives a DC power source Pdc and is electrically connected to a load 300 (i.e., a critical load). The resonant converter 100 is, for example, an LLC converter, and the resonant converter 100 includes a primary-side circuit 1A, a transformer 2A, a secondary-side circuit 3A, and a controller 4A in a system control circuit MCU for controlling the resonant converter 100. One end of the primary-side circuit 1A receives the DC power source Pdc, and the other end is electrically connected to the primary-side winding 22A of the transformer 2A. The secondary-side winding 22B of the transformer 2A is electrically connected to one end of the secondary-side circuit 3A, and the other end of the secondary-side circuit 3A is electrically connected to the load 300. The controller 4A is electrically connected to the primary-side circuit 1A and the secondary-side circuit 3A, and controls the resonant converter 100 to convert the DC power source Pdc into the output power source Po by controlling the primary-side circuit 1A and the secondary-side circuit 3A.

[0121] The resonant converter 100 includes various implementation structures. For example, the primary side circuit 1A may be a half-bridge type (see Figure 3A to Figure 3C ), full-bridge type, etc. The secondary side circuit 3A can be a half-bridge type, a center tap type (see Figure 3A-3B ), full bridge (see Figure 3C ) and other structures, and the secondary side circuit 3A can be a single group or multiple groups connected in parallel. The number of secondary side windings 22B depends on the number of secondary side circuits 3A, for example Figure 3A 、 Figure 3C The number of primary windings 22A is an integer multiple of the number of secondary windings 22B. Figure 3A It's two to two. Figure 3C The resonant converter 100 can also be composed of multiple groups of resonant conversion circuits 100A, for example Figure 3B The architecture consists of two groups Figure 3A The primary side circuit 1A is connected in series through the primary side winding 22A, and the output ends of the secondary side circuit 3A are connected in parallel.

[0122] For reference Figure 3A-3B The primary-side circuit 1A includes a primary-side switching arm SP_1 and a resonant tank (e.g., a series-connected resonant inductor Lr and resonant capacitor Cr). The primary-side switching arm SP_1 includes two series-connected power switches Q1 and Q2, forming a primary-side topology. The secondary-side circuit 3A includes a rectifier circuit 32 and an output capacitor Co. The rectifier circuit 32 includes a first switch SR1 and a second switch SR2. The secondary-side winding 22B includes a first winding 22B-1 and a second winding 22B-2, each of which is center-tapped. One end of the first winding 22B-1 and the second winding 22B-2 are electrically connected to one end of the first switch SR1 and the second switch SR2, respectively. The other ends of the first winding 22B-1 and the second winding 22B-2 are electrically connected to one end of the output capacitor. The other end of the first switch SR1 and the other end of the second switch SR2 are electrically connected to the other end of the output capacitor, and the output capacitors Co of each set of secondary-side circuits 3A are connected in parallel to form a secondary-side topology.

[0123] The controller 4A controls the primary-side switch bridge arm SP_1 and the first switch SR1 and the second switch SR2 of the rectifier circuit 32 to store / release energy in the resonant tank and the transformer 2A. The DC power Pdc received by the resonant converter 100 is converted into an output power Po through the energy storage / release of the resonant tank and the transformer 2A to supply power to the load 300. Figure 3C and Figure 3A 、 Figure 3B The difference lies in that the rectifier circuit 32 includes secondary-side switching arms SS_1 and SS_2. The secondary-side switching arms SS_1 and SS_2 are connected in parallel and include a first switch SR1 and a third switch SR3 connected in series. The secondary-side switching arm SS_2 includes a fourth switch SR4 and a second switch SR2 connected in series, and the two ends of the secondary-side winding 22B are electrically connected to the series node between the first switch SR1 and the third switch SR3 and the series node between the fourth switch SR4 and the second switch SR2, respectively. In other embodiments, the primary-side circuit 1A, transformer 2A, and secondary-side circuit 3A of the resonant converter 100 may vary based on different design considerations. For example, the primary-side circuit 1A may utilize a full-bridge configuration, the transformer 2A may include only a single primary-side winding 22A and a secondary-side winding 22B, and the secondary-side circuit 3A may utilize a half-bridge configuration, and so on.

[0124] See also Figure 4A A first perspective view of the three-dimensional circuit structure combination of the second embodiment of the resonant converter disclosed herein, Figure 4B This is a second perspective view of the three-dimensional circuit structure combination of the second embodiment of the resonant converter disclosed in the present invention, and is used in conjunction with Figure 4A . Figure 4A 、 Figure 4B Mainly, the circuit of the resonant converter 100 (for example: Figures 3A to 3C The circuit diagram (see circuit diagram) is converted into a physical structure consisting of two circuit boards CB1 and CB2. This allows the resonant converter 100, consisting of circuit boards CB1 and CB2, to convert a DC power source Pdc into an output power source Po. In its physical structure, resonant converter 100 includes first and second circuit boards CB1 and CB2, a primary circuit 1A, a secondary circuit 3A, and a planar transformer PE serving as transformer 2A. The first circuit board CB1 comprises multiple sub-layer boards, with an input terminal IN and an output terminal OUT formed on the edge of the first circuit board CB1. The input terminal IN of the first circuit board CB1 receives the DC power source Pdc, and the output terminal OUT provides the output power source Po. The input terminal IN and the output terminal OUT are formed on the edge of the second circuit board CB2, which also provides the output power source Po. The formation of the input terminal IN and the output terminal OUT on the edges of the circuit boards CB1 and CB2 primarily allows the circuit boards CB1 and CB2 to be plugged into any device requiring power conversion, such as a power supply or uninterruptible power supply system. Vertical plugging saves device space.

[0125] The primary side circuit 1A is disposed on the first circuit board CB1 and the second circuit board CB2. The circuit components of the primary side circuit 1A that can be clearly seen on the first circuit board CB1 include the power switches Q1 and Q2 of the primary side switch bridge arm SP_1 and the inductor core CL used to form the resonant inductor Lr. Figure 4B The second circuit board CB2 includes part of the circuitry of the resonant converter 100. Specifically, the first circuit board CB1 includes a portion of the inductor winding Lc of the resonant inductor Lr and a portion of the winding 22 of the transformer 2A, while the second circuit board CB2 includes another portion of the inductor winding Lc and another portion of the winding 22 of the transformer 2A. The iron core C1 nests the first and second circuit boards CB1 and CB2 together to form the transformer 2A of the resonant converter 100.

[0126] For reference Figure 3A to Figure 3C 、 Figure 4A-4BThe resonant converter 100, constructed on two circuit boards CB1 and CB2, includes two (or more) sets of secondary-side circuits 3A. Thus, the first circuit board CB1 and the second circuit board CB2 can each be provided with a set of secondary-side circuits 3A. The circuit components of the secondary-side circuit 3A, which can be clearly seen on the circuit boards CB1 and CB2, include the first switch SR1 and the second switch SR2 of the rectifier circuit 32, and the output capacitor Co. A planar transformer PE is provided on the first circuit board CB1 and the second circuit board CB2, electrically connecting the primary-side circuit 1A and the secondary-side circuit 3A. The planar transformer PE includes an iron core C1, which forms the planar transformer PE. The resonant inductor Lr and the planar transformer PE are arranged on the circuit boards CB1 and CB2 using traces, enabling a planar structure. This replaces the larger winding-type transformer / inductor used, thereby reducing the volume occupied by the resonant converter 100. The system control circuit MCU (including the controller 4A for controlling the resonant converter 100 ) may be disposed on the first circuit board CB1 or the second circuit board CB2 , and the system control circuit MCU may communicate with external devices via the signal transmission terminal SG disposed on the first circuit board CB1 or the second circuit board CB2 .

[0127] See also Figure 4C This is a third perspective view of the three-dimensional circuit structure combination of the second embodiment of the resonant converter disclosed in the present invention. Figure 3A to Figure 3C 、 Figure 4A-4B The flat transformer PE further includes a conductive post PC_1, and the conductive post PC_1 is disposed between the first circuit board CB1 and the second circuit board CB2. Since the first circuit board CB1 includes a portion of the transformer 2A winding 22 formed by the traces, and the second circuit board CB2 includes another portion of the transformer 2A winding 22 formed by the traces, these portions of the winding 22 can be electrically connected together through the conductive post PC_1 to form a complete winding 22. Figure 4D This is a three-dimensional circuit structure decomposition diagram of the second embodiment of the resonant converter disclosed herein, which mainly decomposes the inductor core CL of the resonant inductor Lr and the core C1 of the transformer 2A. The flat transformer PE also includes a first circuit board through-hole CB1_H, a second circuit board through-hole CB2_H, a primary side winding 22A and a secondary side winding 22B.

[0128] The first circuit board through-hole CB1_H includes a first through-hole H1 and a second through-hole H2, each extending through the first circuit board CB1. The second circuit board through-hole CB2_H includes a third through-hole H3 and a fourth through-hole H4, each extending through the second circuit board CB2. The primary winding 22A and the secondary winding 22B respectively surround the first through-hole H1 and the second through-hole H2 of the first circuit board through-hole CB1_H, and the third through-hole H3 and the fourth through-hole H4 of the second circuit board through-hole CB2_H. In other words, the primary winding 22A and the secondary winding 22B are formed in a routing structure on the sub-layers of the first circuit board CB1 and the second circuit board CB2, respectively, and surround the first circuit board through-hole CB1_H and the second circuit board CB2. The primary winding 22A and the secondary winding 22B are encased in the core C1 to form a flat-plate transformer PE.

[0129] In this embodiment, the core C1 can be an EI, EE, ER or other type of core. The core C1 includes two covers C1_1 and C1_2, and at least one of the two covers C1_1 and C1_2 forms a first core column C12 and a second core column C14. The two covers C1_1 and C1_2 also include a main body and multiple side portions C1_3, respectively, and the side portions C1_3 of the two covers C1_1 and C1_2 correspondingly protrude from the periphery of the main body. A receiving groove C1_4 is formed between the side portions C1_3 of the two covers C1_1 and C1_2 and the first core column C12 and the second core column C14, and the receiving groove C1_4 is used to accommodate part of the winding 22 of the first circuit board CB1 and another part of the winding 22 of the second circuit board CB2. In this embodiment, the winding 22 can be a primary side winding 22A and a secondary side winding 22B, and in other embodiments, for example: the winding 22 can be Figure 3A to Figure 3C At least one of the primary side winding 22A and the secondary side winding 22B.

[0130] If Figure 3A to Figure 3C Circuit implementation Figures 4A to 4D In this circuit structure, since the primary-side windings 22A of the resonant converter 100 are connected in series, a portion of the primary-side windings 22A on the first circuit board CB1 and another portion of the primary-side windings 22A on the second circuit board CB2 can be electrically connected via conductive posts PC_1 to form a complete primary-side winding 22A. Since the secondary side of the resonant converter 100 includes two sets of secondary-side circuits 3A, each with parallel outputs, the first circuit board CB1 and the second circuit board CB2 can each be provided with a set of secondary-side windings 22B. Since the secondary side of the transformer 2A is a parallel structure, the secondary-side windings 22B of the first circuit board CB1 and the second circuit board CB2 do not require conductive posts for electrical connection; they can be electrically connected to each other simply by connecting their respective output terminals OUT in parallel.

[0131] The flat-plate transformer PE is covered by two covers C1_1 and C1_2, so that the first core leg C12 extends through the first through-hole H1 of the first circuit board through-hole CB1_H and the third through-hole H3 of the second circuit board through-hole CB2_H, and the second core leg C14 extends through the second through-hole H2 of the second circuit board through-hole CB2_H and the fourth through-hole H4 of the second circuit board through-hole CB2_H. Thus, the first circuit board CB1 and the second circuit board CB2 can be nested together by the two covers C1_1 and C1_2 to form the transformer 2A of the resonant converter 100. See also Figures 4A to 4C The side portion C1_3 located outside the first and second circuit boards CB1 and CB2 forms an air gap GP. This air gap GP is formed outside the first and second circuit boards CB1 and CB2, making it easy to adjust the size of the air gap GP and thereby adjust the magnetic resistance of the planar transformer PE, thereby preventing magnetic saturation during circuit operation. Because the air gap GP is located between the first and second circuit boards CB1 and CB2, the magnetic flux lines generated around the air gap GP are less likely to intersect the primary winding 22A and the secondary winding 22B. This creates an air gap avoidance effect, reducing heat loss in the windings and improving efficiency.

[0132] In this embodiment, the core C1 includes two core legs C12 and C14, which extend through the first circuit board through-hole CB1_H (i.e., the first through-hole H1 and the second through-hole H2) and the second circuit board through-hole CB2_H (i.e., the third through-hole H3 and the fourth through-hole H4) of the first circuit board CB1 and the second circuit board CB2, respectively. In other embodiments, for example, the first circuit board CB1 and the second circuit board CB2 may include only a single through-hole (i.e., the first circuit board through-hole CB1_H includes only the first through-hole H1, and the second circuit board CB2 includes only the third through-hole H3), with the winding 22 wrapped around this single through-hole. Furthermore, the single core leg C12 of the core C1 extends through the first through-hole H1 and the third through-hole H3, thereby forming a flat-plate transformer PE. The conductive pillar PC_1 also electrically connects the primary-side traces disposed around the first circuit board through-hole CB1_H and the primary-side traces disposed around the second circuit board through-hole CB2_H to form a primary-side winding 22A. The secondary-side traces can form a secondary-side winding 22B without the use of a conductive pillar for electrical connection, and the sum total becomes the winding 22 of the flat-plate transformer PE.

[0133] For reference Figures 4A to 4DThe resonant converter 100 further includes inductor through-holes HL1 and HL2 and an inductor winding Lc. The inductor through-holes HL1 and HL2 include a first inductor through-hole HL1 formed on the first circuit board CB1 and a second inductor through-hole HL2 formed on the second circuit board CB2. The first inductor through-hole HL1 and the second inductor through-hole HL2 extend through the first circuit board CB1 and the second circuit board CB2, respectively. The inductor winding Lc is electrically connected to the winding 22 and surrounds the inductor through-holes HL1 and HL2. Similar to the winding 22 of the transformer 2A, the inductor winding Lc is formed in a routing structure on the sub-layers of the first circuit board CB1 and the second circuit board CB2, respectively. The first circuit board CB1 may include a portion of the inductor winding Lc, and the second circuit board CB2 may include another portion of the inductor winding Lc. The planar transformer PE further includes a conductive post PC_2, which is also disposed between the first circuit board CB1 and the second circuit board CB2. Because the first circuit board CB1 includes a portion of the inductor winding Lc, and the second circuit board CB2 includes another portion of the inductor winding Lc, these portions of the inductor winding Lc can be electrically connected together via the conductive pillar PC_2 to form a complete inductor winding Lc. The inductor core CL nests the inductor windings Lc of the first and second circuit boards CB1 and CB2 together to form the resonant inductor Lr of the resonant converter 100.

[0134] In this embodiment, the inductor core CL can be a core of a UI, UU, or other type. The inductor core CL includes two covers CL_1 and CL_2, each of which includes a main body. At least one of the covers CL_1 and CL_2 includes two side portions CL_3. The two side portions CL_3 protrude from the periphery of the main body, and one of the side portions CL_3 extends through the inductor through-holes HL1 and HL2. A receiving groove CL_4 is formed between the side portions CL_3 of the two covers CL_1 and CL_2. The receiving groove CL_4 is used to accommodate a portion of the inductor winding Lc on the first circuit board CB1 and another portion of the inductor winding Lc on the second circuit board CB2. Portions of the side portions C1_3 of the two covers CL_1 and CL_2 are located outside the circuit boards CB. In this embodiment, the side portions C1_3 located outside the first and second circuit boards CB1 and CB2 form an air gap GP, which functions similarly to the air gap GP of the core C1.

[0135] In one embodiment, the conductive pillars PC_1 and PC_2 are, for example, copper pillars, aluminum pillars, or other pillars having a conductive function. In another embodiment, the resonant converter 100 of the present disclosure may include, in addition to the conductive pillars PC_1 and PC_2, a plurality of pillars PC (e.g., Figure 4D(As shown). The various pillars PC can be made of suitable materials based on their functions. For example, some pillars PC, like conductive pillars PC_1 and PC_2, can have conductive properties to guide current flow and serve as supports for the first and second circuit boards CB1 and CB2, while other pillars PC can be made of non-conductive materials and serve solely as supports.

[0136] like Figures 4A to 4D As shown, the first circuit board CB1 is also provided with an auxiliary power supply circuit AUX, and the auxiliary power supply circuit AUX is electrically connected to the input terminal IN to receive a DC power supply Pdc. The auxiliary power supply circuit AUX can be an isolated conversion circuit (for example: a flyback conversion circuit), and includes a transformer 2B. The transformer 2B is similar to the transformer 2A, and the wiring can be set on the first circuit board CB1, and the transformer 2B is formed by being sheathed through the iron core C2. The iron core C2 can also correspond to the iron core C1, forming an air gap GP on the side, and its function is also the same as the air gap GP of the iron core C1. In one embodiment, the controller (not shown) of the auxiliary power supply circuit AUX can also be selectively integrated into the system control circuit MCU, which is not limited here. Therefore Figure 4A 、 Figure 4B The single circuit board CB shown can include the auxiliary power circuit AUX, the system control circuit MCU and the resonant converter 100, and saves a lot of wiring space and at least saves Figure 2 Space SE.

[0137] For reference Figure 5A is a wiring structure diagram of one surface layer of the first circuit board of the second embodiment, and Figure 5BThis is a wiring diagram of another surface layer of the first circuit board of the second embodiment. DC power supply Pdc enters from input terminal IN and passes through the primary-side switch bridge arm SP_1 and resonant inductor Lr to the flat-type transformer PE. DC power supply Pdc is also provided to the auxiliary power circuit AUX, which converts DC power supply Pdc into auxiliary power supply Paux. Through the coupling of primary-side winding 22A and secondary-side winding 22B, the flat-type transformer PE provides energy to the rectifier circuit 32 and output capacitor Co, and finally provides output power Po to the load 300 from the output terminal OUT. Based on the above-described path, the high-current path (referred to as the power path) of the first circuit board CB1 from the input terminal IN to the output terminal OUT forms an n-type path as described above. The system control circuit MCU and its peripheral control and compensation circuits are located in the center of the n-type path, separated from the power path. The signal transmission terminal SG is directly electrically connected to the system control circuit MCU. The system control circuit MCU is short in distance from the power switches Q1, Q2, the first switch SR1, and the second switch SR2, and is less likely to pass through the power path and be separated from the power path. Therefore, noise in the power path is less likely to interfere with signal transmission in the system control circuit MCU, thereby reducing path loss on the transmission path.

[0138] exist Figure 5B In the figure, the other side opposite the location of the control circuit MCU includes a DC / DC converter circuit, which is mainly composed of several small step-down converters (e.g., Buck). The main reason for configuring several step-down converters is that the auxiliary power Paux converted by the auxiliary power circuit AUX is a single voltage (e.g., but not limited to 12V). However, certain controllers, drivers, etc. on the first circuit board CB1 require different power supplies (e.g., but not limited to 5V, 3.3V, 1.8V, etc.). Therefore, by using several small step-down converters in the DC / DC converter circuit to convert power, it is possible to convert the power into a suitable voltage to supply these components for normal operation. The power switches Q1 and Q2 of the primary-side switching bridge arm SP_1 are, for example, GaN transistors, and the power switches Q1 and Q2 are arranged with the shortest path. The secondary-side winding 22B and the first and second switches SR1 and SR2 are also arranged with the shortest path to facilitate the layout of the output terminal OUT. On the other hand, the routing distances of the secondary winding 22B, the first switch SR1, the second switch SR2, and the output capacitor Co are closely related to their AC impedance. Therefore, the closer the first switch SR1, the second switch SR2, and the output capacitor Co are to the secondary winding 22B, the smaller the AC impedance and the better the efficiency.

[0139] For reference Figure 6A is a wiring structure diagram of one surface layer of the second circuit board of the second embodiment, and Figure 6BThis is a wiring structure diagram of another surface layer of the second circuit board of the second embodiment. The second circuit board CB2 may optionally include a signal transmission terminal SG, so that the second circuit board CB2 can communicate with an external device directly through the signal transmission terminal SG without transmitting the signal back to the first circuit board CB1. The second circuit board CB2 can be electrically connected to the first circuit board CB1 through the conductive columns PC_1 and PC_2 to receive the DC power supply Pdc. In one embodiment, the second circuit board CB2 is not provided with an auxiliary power circuit AUX, so the second circuit board CB2 can save space for providing the auxiliary power circuit AUX, making the board length of the second circuit board CB2 shorter than that of the first circuit board CB1 (see Figures 4A to 4D ).

[0140] For reference Figure 6B The second circuit board CB2 may also include a system control circuit MCU or a DC / DC converter circuit on both sides. The DC / DC converter circuit may consist of at least one small step-down converter. Its functions are similar to those of the system control circuit MCU and DC / DC converter circuit on the first circuit board CB1, primarily enabling communication with external devices via the signal transmission port SG or converting voltages to power certain controllers, drivers, and other components on the second circuit board CB2. Because the resonant converter 100 utilizes a four-sided physical structure with two circuit boards CB1 and CB2, it can evenly distribute heat, effectively increasing the heat dissipation area. The resonant converter 100 also utilizes the distributed arrangement of the windings 22 of the resonant converter 100 across the two circuit boards CB1 and CB2, thereby reducing heat generation and improving circuit efficiency. Because the resonant converter 100 utilizes a primary-side series and secondary-side parallel configuration, the first switch SR1 and the second switch SR2 of the secondary-side circuit 3A can be distributed across the circuit boards CB1 and CB2, providing improved heat dissipation.

[0141] See also Figures 7A to 7H Schematic diagrams of the wiring of the windings of the flat-plate transformer of the present disclosure on the first circuit board of the second embodiment on each sub-layer board. In this embodiment, the first circuit board CB1 is taken as an example with 8 layers of sub-layer boards LA1-1 to LA1-8, and the sub-layer boards LA1-1 to LA1-8 are sequentially from the top board to the bottom board. In other embodiments, the number of layers of the first circuit board CB1 can be increased or decreased according to actual circuit requirements. Figure 3A to Figure 3CAmong the traces on sub-layer boards LA1-1 to LA1-8, inductor trace Tl-1 serves as the resonant inductor Lr, and is provided in the inductor winding Lc (i.e., part of the inductor winding Lc) on the first circuit board CB1. Primary-side trace Tp-1 serves as the primary-side winding 22A (i.e., part of the primary-side winding 22A) on the first circuit board CB1 of transformer 2A. Secondary-side trace Ts-1 serves as the secondary-side winding 22B on the first circuit board CB1 of transformer 2A, and secondary-side trace Ts-1 includes a first secondary-side trace Ts1-1 and a second secondary-side trace Ts2-1. First secondary-side trace Ts1-1 serves as the first winding 22B-1 on the first circuit board CB1, and second secondary-side trace Ts2-1 serves as the second winding 22B-2 on the first circuit board CB1.

[0142] In this embodiment, the copper foil of the primary trace Tp-1 and the copper foil of the inductor trace Tl-1 are integrally formed to form a common trace structure. The primary trace Tp-1 and the secondary trace Ts-1 are located on different sub-layers LA1-LA8 to ensure even current distribution when current flows through the sub-layers LA1-1-LA1-8. In other embodiments, the inductor trace Tl-1, primary trace Tp-1, and secondary trace Ts-1 can be located on the same sub-layers LA1-1-LA1-8 depending on actual circuit requirements. The primary trace Tp-1 and secondary trace Ts-1 are respectively formed and wrapped around the first through-hole H1 and the second through-hole H2 of the first circuit board through-hole CB1_H, and the inductor trace Tl-1 is formed and wrapped around the first inductor through-hole HL1.

[0143] See also Figures 8A to 8H The following are schematic diagrams of the wiring of the windings of the flat-plate transformer of the present disclosure on the second circuit board of the second embodiment on each sub-layer board. In this embodiment, the second circuit board CB2 takes 8 layers of sub-layer boards LA2-1 to LA2-8 as an example (top board to bottom board in order), and the number of layers of sub-layer boards LA2-1 to LA2-8 of the second circuit board CB2 is the same as that of the first circuit board CB1 to make the current average, which is a preferred embodiment. In other embodiments, the number of layers of the second circuit board CB2 can also be increased or decreased according to actual circuit requirements. Figure 3A to Figure 3C 、 Figures 8A to 8HAmong the traces on the sub-layer boards LA2-1 to LA2-8, the structures and functions of the first secondary trace Ts1-2 and the second secondary trace Ts2-2 of the inductor trace Tl-2, the primary trace Tp-2, and the secondary trace Ts-2 are similar to those of the corresponding traces on the first circuit board CB1. The difference is that the positions of the first secondary trace Ts1-2 and the second secondary trace Ts2-2 are swapped. The purpose of swapping the positions of the first secondary trace Ts1-2 and the second secondary trace Ts2-2 is to allow the current of the secondary circuit 3A to be evenly distributed during operation, rather than being concentrated on the two adjacent sub-layer boards. That is, if the current of the secondary circuit 3A is Figure 7H and Figure 8A Both are first secondary-side traces Ts1 - 1 and Ts1 - 2 , and when the first switch SR1 is turned on, these two layers are more adjacent and therefore less likely to evenly distribute the current.

[0144] For reference Figures 7A to 8H The primary-side trace Tp-1 of the first circuit board CB1 is electrically connected to the primary-side trace Tp-2 of the second circuit board CB2 via a conductive post PC_1, forming a primary-side series connection. The iron core C1 is sheathed around the primary-side trace Tp-1, primary-side trace Tp-2, and secondary-side traces Ts-1 and Ts-2, forming a closed magnetic circuit and forming transformer 2A. The inductor trace Tl-1 of the first circuit board CB1 is electrically connected to the inductor trace Tl-2 of the second circuit board CB2 via a conductive post PC_2. The inductor core CL is sheathed around the inductor traces Tl-1 and Tl-2, forming a closed magnetic circuit and forming the resonant inductor Lr. In one embodiment, the primary-side circuit 1A is disposed on the first circuit board CB1 and the second circuit board CB2 mainly because the circuit boards CB1 and CB2 each have inductor traces Tl-1 and Tl-2. However, the inductor traces Tl-1 and Tl-2 can also be both disposed on the first circuit board CB1 and then electrically connected to the primary-side winding 22A of the first circuit board CB1 or electrically connected to the primary-side winding 22A through conductive pillars PC_1, PC_2, and pillar PC. Therefore, the primary-side circuit 1A can be disposed only on the first circuit board CB1.

[0145] exist Figures 7C to 7FIn the corresponding figures 8C-8F, primary-side traces Tp-1 and Tp-2 each wrap around the first PCB through-hole CB1_H and the first PCB through-hole CB2_H at least once (depending on the turns ratio of transformer 2A) in different directions, forming a ∞-shaped trace. Multiple vias Via_A are formed on one side of the first through-hole H1 and second through-hole H2 of the first PCB through-hole CB1_H, and on one side of the third through-hole H3 and fourth through-hole H4 of the second PCB through-hole CB2_H. The vias Via_A are located at the tail ends of the primary side traces Tp-1 and Tp-2, and the inside of the vias Via_A is filled with conductive material (for example, but not limited to, conductive materials such as solder cake), so that the primary side traces Tp-1 and Tp-2 of each sub-layer board LA1-3 to LA1-6, LA2-3 to LA2-6 can be electrically connected through the vias Via_A, and the two primary side traces Tp-1 and Tp-2 are electrically connected through the conductive column PC_1 to form a primary side winding 22A.

[0146] exist Figures 7A and 7B 、 Figures 7G to 7H In the embodiment, the secondary-side trace Ts-1 forms an M-shaped trace with the first through-hole H1 and the second through-hole H2 of the first circuit board CB1. Due to Ampere's right-hand rule, the direction of current determines the direction of the magnetic field. Therefore, the current in the primary-side trace Tp-1 formed and encircling the first through-hole H1 flows in the same direction as the secondary-side trace Ts-1 (e.g., clockwise). The current in the primary-side trace Tp-1 formed and encircling the second through-hole H2 flows in the opposite direction of the first through-hole H1 (e.g., counterclockwise). Multiple vias Via_B may be included near the output terminal OUT of the secondary-side trace Ts-1. The vias Via_B are filled with conductive material. This allows the secondary-side traces Ts-1 on the sub-layers LA1-1, LA1-2, LA1-7, and LA1-8 to be electrically connected via the vias Via_B to form a secondary-side winding 22B. Figures 8A and 8B 、 Figures 8G to 8H The secondary-side trace Ts-2 can be electrically connected to the secondary-side trace Ts-1 through the via Via_B to form another secondary-side winding 22B.

[0147] exist Figure 7F 、 Figure 8FIn the embodiment, the inductor trace Tl-1 is formed and surrounds the first inductor through-hole HL1, and the inductor trace Tl-2 is formed and surrounds the second inductor through-hole HL2. In this embodiment, the copper foil of the inductor trace Tl-1 and the primary side trace Tp-1 are an integrally formed structure, and the copper foil of the inductor trace Tl-2 and the primary side trace Tp-2 are an integrally formed structure, so a part of the integrally formed copper foil belongs to the inductor trace Tl-1, and the other part belongs to the primary side trace Tp-1 (the same is true for the inductor trace Tl-2). In other embodiments, the inductor trace Tl-1 and the primary side trace Tp-1 can be set separately (the same is true for the inductor trace Tl-2 and the primary side trace Tp-2), for example, other circuit elements such as a resonant capacitor Cr can be included between the two. In this embodiment, the inductor trace Tl-1, the primary side trace Tp-1 and the secondary side trace Ts-1 are not limited to being arranged in a certain manner. Figures 7A to 7H The first and second sub-layer boards described later are not stacked in the order of stacking, but only represent a sub-layer board LA1-1 and another sub-layer board LA1-8 in the first circuit board CB1.

[0148] For reference Figure 9A For this disclosure Figures 7A to 7H FIG1 is a diagram showing a planar transformer with a stacked structure of traces on each sub-layer of the first circuit board of the second embodiment, and a magnetomotive force curve when the first circuit board is operating on the first secondary side traces. Figure 9A From top to bottom on the left: Figures 7A to 7H The routing stacking structure diagram, and Figure 9A The right side corresponds to Figure 9A The magnetomotive force curve formed by the stacked trace structure on the left. In this embodiment, sub-layers LA1-1 to LA1-2, LA1-7 to LA1-8 form a loop of first secondary-side trace Ts1-1 or second secondary-side trace Ts2-1 centered around through-holes H1 and H2, and sub-layers LA3 to LA6 form a loop of primary-side trace Tp-1 centered around through-holes H1 and H2. The spacing between each trace can be considered the thickness between each sub-layer LA1-1 to LA1-8. In one embodiment, because the first circuit board CB1 has sufficient board space, the insulation layer between the primary and secondary layers (i.e., between sub-layers LA1-2 and LA1-3, and between sub-layers LA1-6 and LA1-7) can be thickened to reduce parasitic capacitance, thereby optimizing dead time and improving efficiency and electromagnetic interference. The horizontal axis of the magnetomotive force graph is magnetomotive force (MMF), and the vertical axis is position. The origin of the vertical axis is the magnetic flux origin M0, and the left and right sides of the magnetic flux origin M0 respectively include a first predetermined offset M1 and a second predetermined offset Mr.

[0149] In this embodiment, the first predetermined offset M1 and the second predetermined offset Mr are ideal predetermined offsets obtained by calculating the parameters of the transformer 2A. During actual operation of the transformer 2A, although the actual offsets may not be completely identical to the first predetermined offset M1 and the second predetermined offset Mr, they may still be within the error range of the first predetermined offset M1 and the second predetermined offset Mr. The formation of the primary-side trace Tp-1 enables the primary-side trace Tp-1 to generate a first-directional magnetic flux F_D1 during operation of the primary-side circuit 1A. The formation of the first secondary-side trace Ts1-1 enables the first switch SR1 of the secondary-side circuit 3A of the first circuit board CB1 to generate a second-directional magnetic flux F_D2 opposite to the first-directional magnetic flux F_D1 during operation of the first switch SR1.

[0150] When the primary-side trace Tp-1 generates a first-directional magnetic flux F_D1, causing a magnetic flux offset, the second-directional magnetic flux F_D2 generated by the first secondary-side trace Ts1-1 offsets the magnetomotive force MMF in the opposite direction to maintain the first-directional magnetic flux F_D1 and the second-directional magnetic flux F_D2 within a specific range Rm formed by the magnetic flux origin M0 and the first predetermined offset M1 and the second predetermined offset Mr. When the flat-plate transformer 2A operates, the magnetomotive force curve CF1 of the first circuit board CB1 is maintained within the specific range Rm, thereby maintaining a balanced magnetomotive force MMF.

[0151] Since only the first switch SR1 or the second switch SR2 operates in the same half-cycle in the center-tap structure of the first winding 22B-1, when the first switch SR1 is on and the second switch SR2 is off, no current path is formed between the second winding 22B-2 and the rectifier switch SR2, causing the magnetomotive force MMF of the second secondary-side trace Ts2-1 to not shift toward the first predetermined offset M1 or the second predetermined offset Mr. Based on the above logic, the magnetomotive force curve when the first switch SR1 is off and the second switch SR2 is on can be inferred, which will not be further described here. Figure 9B For this disclosure Figures 8A to 8H The trace stacking structure of each sub-layer of the second circuit board of the second embodiment of the planar transformer is combined with the magnetomotive force curve of the second circuit board during operation of the first secondary-side traces. Because the trace stacking structure of each layer of the second circuit board CB2 is identical to that of the first circuit board CB1, the trace stacking structure of the second circuit board CB2 can also maintain the first-direction magnetic flux F_D1 and the second-direction magnetic flux F_D2 within the specific range Rm defined by the magnetic flux origin M0 and the first and second predetermined offsets M1 and Mr. This maintains the magnetomotive force curve CF2 of the second circuit board CB2 within the specific range Rm during operation of the planar transformer 2A, thereby maintaining a balanced magnetomotive force MMF.

[0152] See also Figure 10A This is a cross-sectional view of a circuit board using embedded technology for the power components of the resonant converter disclosed herein. In this embodiment, the power path of the resonant converter 100 (see Figure 3A ) on the circuit board CB (e.g., power switches Q1, Q2, first switch SR1, second switch SR2, output capacitor Co (non-electrolytic capacitor), and a driver for turning on switches Q1, Q2, SR1, and SR2) can be embedded using embedding technology into any of the sub-layers LA1-1 through LA1-8, LA2-1 through LA2-8 (illustrated using sub-layer LA1-1) within the circuit board CB. The primary purpose and effectiveness of using embedding technology is to minimize the AC impedance AC_R of the resonant converter 100 and thereby improve circuit efficiency. Embedding technology involves hollowing out the resin substrate within circuit boards CB1 and CB2, then embedding the power components 400, such as the power switches and driver, within the hollowed-out area AR_H. Then, copper is melted into the pre-formed vias Via_D on the circuit boards CB1 and CB2 to form contact pads on the surface, so that the power element 400 can be electrically connected to components such as electronic components Ce (such as capacitors, resistors, etc.), any traces of the winding 22, and electrical traces Tc for electrically connecting to the electronic components Ce through the vias Via_D. Figure 10B This is a top view of a circuit board using embedding technology for the power components of the resonant converter disclosed herein. Electronic components Ce (e.g., capacitors, resistors, switches) or electrical traces Tc can be electrically connected to the power component 400 by soldering to contact pads. This technique is used because once the power component 400 is embedded in the hollowed-out area AR_H, the electronic components Ce or electrical traces Tc can be connected to the power component 400 using the shortest possible distance, thereby minimizing the AC impedance AC_R of this connection path.

[0153] For reference Figure 10C and Figure 10D A circuit diagram showing the application of embedded technology to the power elements on the secondary side of the resonant converter of the present disclosure. Figure 10C and Figure 10D The embodiment mainly involves the power element 400 on the secondary side of the resonant converter 100 (e.g., the first switch SR1, the second switch SR2, the controller IC_SR for controlling the first switch SR1 and the second switch SR2, the output capacitor Co, etc., and the output capacitor Co is electrically connected to the first switch SR1 and the second switch SR2 to form the secondary side circuit 3A) can be applied as follows Figures 10A and 10BThe embedded technology shown is used to embed any sub-layer board of the circuit boards CB1 and CB2 (for example, embedded in the surface boards LA1-1 and LA1-8 of the circuit board CB1), and then by melting copper into the preset vias Via_D, contact pads are generated on the surface of the sub-layer boards LA1-1 and LA1-8. As a result, the circuit board CB1 has only contact pads at the locations of the multiple power components 400, and the power components 400 (first switch SR1, second switch SR2 and output capacitor Co) can be electrically connected to the secondary side winding 22B through the corresponding multiple vias Via_D. In one embodiment, the secondary side power component 400 is set in the first circuit board through-hole CB1_H (see Figures 4A to 4D The first circuit board through-hole CB1_H can be one side of the first through-hole H1 or the second through-hole H2, and the first switch SR1 and the second switch SR2 are respectively arranged on the two sides of the output capacitor Co, and the sub-layer boards LA1-1 and LA1-8 are provided with the first secondary-side trace Ts1-1, and the sub-layer boards LA1-2 and LA1-7 are provided with the second secondary-side trace Ts2-1.

[0154] Taking the first circuit board CB1 as an example, because multiple power components 400 utilize embedded technology, they are not affected by the first secondary trace Ts1-1 on the surface of the circuit board CB1, or by other electronic components Ce and controller IC_SR, and are therefore not forced to adjust to a connection path other than the shortest distance. This allows a shorter current path to be formed when current I1 flows through the first switch SR1, the first secondary trace Ts1-1, and the output capacitor Co. (The same applies to current I2. Furthermore, because the power components 400 are all disposed on sub-layers LA1-1 and LA1-8, the second secondary traces Ts2 on sub-layers LA1-2 and LA1-7 can be electrically connected to the power components 400 via contact pads.) The structure and features of the second circuit board through-hole CB2_H are similar and will not be further described here.

[0155] For reference Figure 10C and Figure 10D , the embedded technology can also be applied to the primary side of the resonant converter 100. Figures 3A to 4D The primary side circuit 1A includes a primary side switch bridge arm SP_1, and the primary side switch bridge arm SP_1 includes a first power switch Q1 and a second power switch Q2. The first power switch Q1 and the second power switch Q2 can be similar to Figure 10C and Figure 10D The embedding technology is used to embed the circuit board in any sub-layer of the first circuit board CB1 , and the first power switch Q1 and the second power switch Q2 are electrically connected to the primary winding 22A through corresponding multiple vias Via_D.

[0156] See also Figure 10EThe top and cross-sectional views of a circuit board of the first embodiment of the present disclosure using embedding technology for the planar transformer routing. In addition to power element 400, the inductor winding Lc of resonant inductor Lr and winding 22 of planar transformer PE can also be embedded using embedding technology into any of the sub-layers LA1-1 through LA1-8 and LA2-1 through LA2-8 of circuit boards CB1 and CB2 (sub-layer LA1-1 is used as an example). The embedding technology for the resonant inductor Lr and the planar transformer PE primarily utilizes a modular winding WM structure for the inductor winding Lc and winding 22 (i.e., modular winding WM includes inductor traces Tl-1 and Tl-2 forming inductor winding Lc, or includes primary-side traces Tp-1 and Tp-2 or secondary-side traces Ts-1 and Ts-2 forming winding 22). Similarly, the resin substrates within the circuit boards CB1 and CB2 are hollowed out, and the modular inductor winding Lc and winding 22 (i.e., modular winding WM) are embedded within the hollowed-out area AR_H. Copper is then melted into pre-formed vias (Via_D) within the circuit boards CB1 and CB2 to create surface contacts (Pads). This allows the primary circuit 1A or the secondary circuit 3A to electrically connect to the modular winding WM through the vias (Via_D). In one embodiment, the modular winding WM can be formed by using a non-conductive material such as resin to form a wiring layer structure of the entire inductor winding Lc or winding 22, so that the wiring layer structure can be embedded in the hollow area AR_H of the circuit board CB through embedding technology.

[0157] For reference Figure 10E , and with Figure 7C 、 Figure 7D Taking the primary side trace Tp-1 of the embodiment as traces T_1(n) and T_1(m) to form a modular winding WM as an example, it is assumed that the traces T_1(n) and T_1(m) are embedded in the first sub-layer board LA1-1. Figure 10E Panel (a) shows a top view of traces T_1(n) and T_1(m), and panel (b) shows a cross-sectional view of traces T_1(n) and T_1(m). Traces T_1(n)-T_3(n) on the first (upper) layer of modular winding WM are arranged in the same extension direction DW_1 and are electrically connected to traces T_1(n)-T_3(n) on the second (lower) layer via conductive material MC (e.g., copper, aluminum, etc., preferably in a columnar structure). Traces T_1(m)-T_3(m) on the lower layer are also arranged in the same extension direction DW_2, so that traces T_1-T_3 extend across the first and second layers in an alternating manner through conductive material MC. In one embodiment, the traces T_1 to T_3 on different layers form an acute angle with the conductive material as the center, and when the acute angle is between 25 degrees and 30 degrees, the AC impedance of the modular winding WM is lower, which is a preferred embodiment. Figure 10EWhen embedding technology is applied to the inductor winding Lc and winding 22 of resonant converter 100, modular inductor winding Lc and winding 22 (i.e., modular winding WM) can also be formed in vias (Via_D) on circuit boards CB1 and CB2, creating contact pads on the surface. The modular inductor winding Lc and modular winding 22 can be electrically connected to the primary circuit 1A or the secondary circuit 3A via vias (Via_D).

[0158] The first and second layers are similar to Figure 7C 、 Figure 7D The relationship between the stacking of sub-layer boards LA1-1 and LA1-2 (i.e., the first layer and the second layer are stacked together), but the first layer and the second layer do not refer to the first sub-layer board LA1-1 and the second sub-layer board LA1-2. For example, the first sub-layer board LA1-1 may include the first layer and the second layer of the modular winding WM arranged on the first sub-layer board LA1-1, but it can also be that the first layer of the modular winding WM is arranged on the first sub-layer board LA1-1, and the second layer is arranged on the second sub-layer board LA1-2. There is no limitation here. Contacts Pad_1 and Pad_2 are formed at the initial ends of the upper-layer traces T_1(n) to T_3(n) and the terminal ends of the lower-layer traces T_1(m) to T_3(m), and the contacts Pad_1 and Pad_2 can be electrically connected to the electrical traces Tc_1 and Tc_2 on the top and bottom surfaces of the first sub-layer board LA1-1 (that is, the top surface of the second sub-layer board LA1-2), respectively, so as to electrically connect the power element 400 through the electrical traces Tc_1 and Tc_2.

[0159] For reference Figure 10F The top view and cross-sectional view of the circuit board of the second embodiment of the present disclosure using the embedded technology for the wiring of the flat-plate transformer, and also taking the wiring T_1(n) and T_1(m) to form the modular winding WM as an example. Figure 10F As shown in the top view (a) and the cross-sectional view (b), contacts Pad_1 and Pad_2 are formed at the initial and final ends of upper-layer traces T_1(n)-T_3(n), respectively. Contacts Pad_1 and Pad_2 can be electrically connected to electrical traces Tc_1 and Tc_2 on the top surface of the first sub-layer LA1-1, thereby electrically connecting to power device 400 through electrical traces Tc_1 and Tc_2. Therefore, electrical traces Tc_1 and Tc_2 are located on the same surface, and an isolation layer or a hollow region (i.e., region AR) is included between them to prevent short circuits between them.

[0160] See also Figure 10G This is a side view of a circuit board using embedded technology for routing the power components and flat-plate transformers disclosed herein. Figures 10A to 10GUsing a technology, a power element 400 and a modular winding WM (including traces T_1(n) and T_1(m)) are embedded in any of the sub-layers LA1-1 through LA1-8 and LA2-1 through LA2-8 of the circuit boards CB1 and CB2 (for example, all embedded in the first sub-layer LA1-1 of the first circuit board CB1). The power element 400 can be electrically connected to the traces T_1(n), T_1(m), T_2(n), and T_2(m) of the modular winding WM through two vias Via_D by connecting an electrical trace Tc_1 to two contacts Pad_1. The modular winding WM can also be electrically connected to the electrical trace Tc_2 on the bottom surface of the first sub-layer LA1-1 (which can be the top surface of the second sub-layer LA1-2) through contact Pad_2. Therefore, using the embedding technology can shorten the distance between the power element 400 and the traces T_1(n), T_1(m), T_2(n), and T_2(m), thereby minimizing the AC impedance AC_R and improving circuit efficiency.

[0161] In this embodiment, the power component 400 and the traces T_1(n), T_1(m), T_2(n), and T_2(m) of the modular winding WM are embedded in the same sub-layer LA. This effectively shortens the distance between the power component 400 and the traces T_1(n), T_1(m), T_2(n), and T_2(m). For example, the power component 400 is a first switch SR1, which is embedded in the same sub-layer as the first secondary-side trace Ts1-1. The first switch SR1 is electrically connected to the first secondary-side trace Ts1-1 via the electrical trace Tc_1 and the pad Pad_1, effectively shortening the distance between the two. Similarly, this can be done by analogy. In other embodiments, the power element 400 and the traces T_1(n), T_1(m), T_2(n), and T_2(m) of the modular winding WM may also be embedded in a sub-layer board LA on a different layer. Compared to the traditional power element 400 that must be set on the surface of the circuit boards CB1 and CB2, the power element 400 disclosed in the present invention does not need to be set on the surface of the circuit boards CB1 and CB2. Therefore, other components and traces on the surface of the circuit boards CB1 and CB2 can be avoided, thereby simplifying the complexity of the circuit design.

[0162] See also Figure 11A This is a diagram showing the arrangement of components of the secondary side circuit of the resonant converter disclosed herein. Figures 10C to 10D The secondary side circuits 3A are respectively disposed on the circuit boards CB1 and CB2, and each secondary side circuit 3A includes a first switch SR1, a second switch SR2 and an output capacitor Co. Figure 3A to Figure 3CThe first switch SR1, the second switch SR2, and the output capacitor Co are disposed on circuit boards CB1 and CB2, with the output capacitor Co electrically connecting the first switch SR1 and the second switch SR2. Secondary-side traces Ts-1 and Ts-2 can be disposed on any one or more sub-layers LA1-1 to LA1-8 and LA2-1 to LA2-8 of circuit boards CB1 and CB2, respectively, and are formed around the first circuit board through-hole CB1_H and the second circuit board through-hole CB2_H, respectively. Taking the first circuit board CB1 as an example, one end of the secondary-side trace Ts-1 is electrically connected to the first switch SR1, and the other end of the secondary-side trace Ts-1 is electrically connected to the second switch SR2. For example, when the secondary-side trace Ts-1 is disposed on the surface layer of the circuit board CB1 (e.g., the first sub-layer board LA1-1), the secondary-side trace Ts-1 can be directly connected to the first switch SR1 and the second switch SR2 by soldering the contact pad, or when the secondary-side trace Ts-1 is disposed on the inner layer of the circuit board CB1 (e.g., the second sub-layer board LA1-2), the secondary-side trace Ts-1 can be electrically connected to the first switch SR1 and the second switch SR2 by vias (not shown).

[0163] Taking the first circuit board CB1 as an example, Figure 11A In the embodiment, the first switch SR1 and the second switch SR2 are disposed on the same side of the first circuit board through hole CB1_H, and the output capacitor Co is disposed between the first switch SR1 and the second switch SR2. In one embodiment, when there are multiple output capacitors Co, the output capacitors Co can be configured as follows: Figure 11A As shown, they are arranged in parallel in the same direction, or they can be arranged in parallel in pairs. Due to the specific arrangement of the first switch SR1, the second switch SR2 and the output capacitor Co, when the first switch SR1 and the second switch SR2 are turned on, a ring-shaped current path Li is formed, that is, the current flows from one side of the secondary side trace Ts-1 through the first switch SR1, the output capacitor Co, the second switch SR2 to the other side of the secondary side trace Ts-1. Since the current path Li is in an arc shape, there are no other branches or irregular paths (for example, compare Figure 10C ), so Figure 11A The arrangement of components can provide the shortest current path Li and reduce path loss. The structure of the second circuit board CB2 is also the same, and can also form an arc-shaped current path.

[0164] See also Figure 11B This is a diagram showing the arrangement of components of the resonant converter according to different secondary side circuit structures. Figure 11A . Figure 11B The main structure is a side view of the output terminals OUT of the circuit boards CB1 and CB2 toward the core C1. Taking the first circuit board CB1 as an example, the first switch SR1, the second switch SR2 and the output capacitor Co are arranged in a direction similar to the circuit board CB1. Figure 3A to Figure 3CDifferent secondary side circuits 3A may have different configurations, but may also be configured as follows: Figure 11A The current path Li. Figure 11B In the (a) panel, the first switch SR1, the second switch SR2 and the output capacitor Co are arranged on the same surface of the circuit board CB, and the first secondary side trace Ts1-1 and the second secondary side trace Ts2-1 are respectively arranged on at least any two layers of the circuit board CB1 (illustrated by the first sub-layer LA1-1 and the second sub-layer LA1-2), and Figure 11B The (a) sub-graph is applicable to Figure 3A 、 Figure 3B When the first switch SR1 is turned on, current I1 flows from the first switch SR1 on the first sub-layer board LA1-1 around the through-hole H to the output capacitor Co, forming a current path Li_1. When the second switch SR2 is turned on, current I2 flows from the second switch SR2 on the second sub-layer board LA1-2 around the first circuit board through-hole CB1_H (e.g., first through-hole H1) to the output capacitor Co, forming a current path Li_2. Because current paths Li_1 and Li_2 run in opposite directions, they achieve magnetic flux cancellation, thereby improving overall circuit efficiency. In one embodiment, the structure and current paths of the second circuit board CB2 are similar and will not be further described here.

[0165] exist Figure 11B In panel (b), resonant converter 100 includes two sets of secondary-side circuits 3A and two sets of secondary-side traces Ts-1 and Ts-2, respectively disposed on circuit boards CB1 and CB2. The two sets of secondary-side traces Ts-1 and Ts-2 include first secondary-side traces Ts1-1 and Ts1-2, and second secondary-side traces Ts2-1 and Ts2-2, respectively. Each set of secondary-side circuits 3A includes two sets of first switches SR1 and two sets of second switches SR2, as well as two or more output capacitors Co. The first switches SR1, second switches SR2, and output capacitors Co are respectively disposed on two surfaces of circuit board CB. Taking the first circuit board CB1 as an example, the first secondary side trace Ts1-1 and the second secondary side trace Ts2-1 are respectively set on at least any four layers of the circuit board CB1 (the first secondary side trace Ts1-1 is set on the sub-layer boards LA1-1 and LA1-2, and the second secondary side trace Ts2-1 is set on the sub-layer boards LA1-7 and LA1-8), and Figure 11B The (b) panel is applicable to Figure 3A 、 Figure 3BWhen the first switch SR1 is turned on, current I1 flows through the first switch SR1 on sub-layers LA1-1 and LA1-8, around the first circuit board through-hole CB1_H (e.g., first through-hole H1), to the output capacitor Co, forming a current path Li_1. When the second switch SR2 is turned on, current I2 flows through the second switch SR2 on sub-layers LA1-2 and LA1-7, around through-hole H, to the output capacitor Co, forming a current path Li_2. This similarly achieves magnetic flux cancellation, improving overall circuit efficiency. In one embodiment, the structure and current path of the second circuit board CB2 are similar and are not further described here.

[0166] Taking the first circuit board CB1 as an example, Figure 11B In the (c) panel, the first switch SR1, the second switch SR2, and the output capacitor Co are arranged on one surface of the circuit board CB, and the third switch SR3, the fourth switch SR4, and the output capacitor Co are arranged on the other surface of the circuit board CB. The secondary side trace Ts-1 is arranged on at least any two layers of the circuit board CB (illustrated by sub-layers LA1-1 and LA1-8), and Figure 11B The (c) sub-image is applicable to Figure 3C circuit. When the first switch SR1 and the second switch SR2 are turned on, the current I1 flows from the first switch SR1 and the second switch SR2 in the sub-layer board LA1-1 around the first circuit board through-hole CB1_H (for example, the first through-hole H1) to the output capacitor Co, thereby forming a current path Li_1. When the third switch SR3 and the fourth switch SR4 are turned on, the current I2 in the same trace (i.e., the secondary side trace Ts-1) but in the opposite direction flows from the third switch SR3 and the fourth switch SR4 in the second sub-layer board LA1-2 around the first circuit board through-hole CB1_H (for example, the first through-hole H1) to the output capacitor Co, thereby forming a current path Li_2, and can also achieve the effect of magnetic flux cancellation and improve the overall efficiency of the circuit. In one embodiment, the structure and current path of the second circuit board CB2 are similar to this and will not be described in detail here. In another embodiment, refer to Figure 11A The preferred embodiment is to position the first switch SR1 and the second switch SR2 in a mirror-image arrangement with the output capacitor Co as the center. This arrangement can form substantially identical current paths Li_11 and Li_2, thereby achieving optimal magnetic flux cancellation. Furthermore, the mirror-image arrangement of the first switch SR1 and the second switch SR2 with the output capacitor Co as the center can achieve optimal magnetic flux cancellation. The same applies to the third switch SR3 and the fourth switch SR4.

[0167] For reference Figures 3A to 11BThe resonant converter 100 disclosed herein uses a monolithic circuit board CB, which can be selectively combined with embedded technology, component configuration and other technologies according to actual needs to improve the overall efficiency of the resonant converter 100. In one embodiment, Figures 3A to 11B If the winding 22 described in the embodiment is not specifically named, it can be a general term for the primary winding 22A and the secondary winding 22B, refer to the primary winding 22A alone or the secondary winding 22B alone, or even refer to the first winding 22B-1 or the second winding 22B-2 alone, without limitation. In another embodiment, Figures 3A to 11B If the routing described in the embodiments is not specifically named, it may be a general term for the primary side routing Tp-1, Tp-2 and the secondary side routing Ts-1, Ts-2, or simply refer to the primary side routing Tp-1, Tp-2, or simply refer to the secondary side routing Ts-1, Ts-2, or even simply refer to the first secondary side routing Ts1-1, Ts1-2 or the second secondary side routing Ts2-1, Ts2-2, and there is no limitation here.

[0168] However, the above description is only a detailed description and drawings of preferred specific embodiments of the present invention. However, the features of the present invention are not limited thereto and are not intended to limit the present invention. The full scope of the present invention shall be based on the following claims. All embodiments that conform to the spirit of the claims of the present invention and similar variations thereof shall be included in the scope of the present invention. Changes or modifications that can be easily conceived by those skilled in the art within the scope of the present invention shall be covered by the following patent scope of the present invention.

Claims

1. A resonant converter, comprising: A first circuit board and a second circuit board, wherein the first circuit board and the second circuit board respectively include multiple layers of sub-layer boards; a primary-side circuit, disposed on the first circuit board; Two secondary circuits are respectively provided on the first circuit board and the second circuit board, and the primary circuit or the two secondary circuits include a power element, wherein the power element is embedded in any sub-layer board of the multiple sub-layer boards; A flat-plate transformer is disposed on the first circuit board and the second circuit board and electrically connects the primary-side circuit and the two secondary-side circuits. The flat-plate transformer includes: a first circuit board through-hole, passing through the first circuit board; a second circuit board through-hole, passing through the second circuit board; An iron core, comprising a first iron core column passing through the first circuit board through-hole and the second circuit board through-hole; A plurality of traces are formed around the through-hole of the first circuit board and the through-hole of the second circuit board respectively; a first conductive post disposed between the first circuit board and the second circuit board and electrically connecting a trace disposed around the through-hole of the first circuit board and a trace disposed around the through-hole of the second circuit board to form a winding of the flat-plate transformer; a first via formed on the first circuit board or the second circuit board and used to electrically connect the power element and the winding disposed on any sub-layer board of the plurality of sub-layer boards; The iron core is used to sheath the windings of the first circuit board and the second circuit board to form the flat-plate transformer.

2. The resonant converter as claimed in claim 1 , wherein the power element is a plurality of elements and comprises: two first switches, respectively disposed on the first circuit board and the second circuit board; two second switches, respectively disposed on the first circuit board and the second circuit board; and Two output capacitors are respectively disposed on the first circuit board and the second circuit board, and the two output capacitors are respectively electrically connected to the first switch and the second switch of the same circuit board to form the two secondary-side circuits, and the two first switches, the two second switches, and the two output capacitors are respectively embedded in any sub-layer board of the first circuit board and the second circuit board; Among them, the multiple traces include secondary-side traces and serve as secondary-side windings electrically connecting the two secondary-side circuits respectively, and the first switch, the second switch and the output capacitor of the first circuit board and the second circuit board are electrically connected to the two secondary-side windings through corresponding two first vias respectively.

3. The resonant converter as claimed in claim 1 , wherein the power element is a plurality of power elements and comprises: a first power switch, disposed on the first circuit board; and a second power switch disposed on the first circuit board, the first power switch and the second power switch forming a primary-side switch bridge arm of the primary-side circuit, and the first power switch and the second power switch are respectively embedded in any sub-layer board of the multiple sub-layer boards; The plurality of traces include two primary-side traces respectively arranged on the first circuit board and the second circuit board, serving as a primary-side winding electrically connected to the primary-side circuit, and the first power switch and the second power switch are respectively electrically connected to the primary-side winding through corresponding plurality of first vias.

4. The resonant converter of claim 1 , further comprising: two second filling holes, formed on the first circuit board and the second circuit board respectively; Among them, the winding is a two-module winding, and the two modular windings are respectively embedded in any sub-layer board of the first circuit board and the second circuit board, and the two modular windings are respectively electrically connected to the primary side circuit or the two secondary side circuits through the two second vias.

5. The resonant converter according to claim 4 , wherein the two modular windings respectively comprise: A plurality of conductive materials are respectively formed between a first layer and a second layer of the two modular windings, and the wiring extends through the plurality of conductive materials in an alternating manner between the first layer and the second layer. 6 . The resonant converter as claimed in claim 5 , wherein the trace is disposed in a first extending direction on the first layer, and the trace is disposed in a second extending direction on the second layer. 7 . The resonant converter as claimed in claim 6 , wherein the traces on different layers form an acute angle with the conductive material as the center, and the acute angle is between 25 degrees and 35 degrees.

8. The resonant converter of claim 4 , further comprising: An electrical trace is used to electrically connect the first filling hole and the second filling hole, so that the power element is electrically connected to the modular winding through the electrical trace.

9. The resonant converter of claim 1 , wherein the primary-side circuit comprises: Two modular windings are respectively embedded in any sub-layer board of the first circuit board and the second circuit board, and the two modular windings respectively include an inductor trace; a second conductive post disposed between the first circuit board and the second circuit board and electrically connecting the two modular windings to form an inductor winding; A third via is formed on the first circuit board or the second circuit board and is used to electrically connect the two modular windings to the primary side circuit.

10. A resonant converter comprising: A first circuit board and a second circuit board, wherein the first circuit board and the second circuit board respectively include a plurality of sub-layer boards; a primary-side circuit, disposed on the first circuit board; Two secondary-side circuits are respectively disposed on the first circuit board and the second circuit board, and the two secondary-side circuits respectively include a first switch, a second switch and an output capacitor, and the output capacitor is electrically connected to the first switch and the second switch; A flat-plate transformer is disposed on the first circuit board and the second circuit board and electrically connects the first switch, the second switch, and the output capacitor of the first circuit board and the second circuit board. The flat-plate transformer includes: a first circuit board through-hole, passing through the first circuit board; a second circuit board through-hole, passing through the second circuit board; An iron core, comprising a first iron core column passing through the first circuit board through-hole and the second circuit board through-hole; A primary-side trace is provided on the first circuit board and the second circuit board; Two secondary-side traces are respectively disposed on the first circuit board and the second circuit board and formed around the through-holes of the first circuit board and the second circuit board, wherein one end of the two secondary-side traces is respectively electrically connected to the first switches of the first circuit board and the second circuit board, and the other end of the two secondary-side traces is respectively electrically connected to the second switches of the first circuit board and the second circuit board; and a first conductive post disposed between the first circuit board and the second circuit board and electrically connecting the primary-side traces of the first circuit board and the second circuit board; The iron core is used to sheath the primary-side traces and the two secondary-side traces of the first circuit board and the second circuit board to form the flat-plate transformer; and The first switch of the first circuit board is arranged on the same side of the through-hole of the first circuit board, and the output capacitor of the first circuit board is configured between the first switch and the second switch of the first circuit board. The first switch of the second circuit board is arranged on the same side of the through-hole of the second circuit board, and the output capacitor of the second circuit board is configured between the first switch and the second switch of the second circuit board. 11 . The resonant converter as claimed in claim 10 , wherein the first switch and the second switch are positioned in a substantially mirror-image arrangement with the output capacitor as the center.

12. The resonant converter according to claim 10, wherein the two secondary-side traces respectively comprise: two first secondary-side traces electrically connecting the first circuit board and the first switch of the second circuit board respectively; and The second secondary side wiring electrically connects the second switch of the first circuit board and the second circuit board to the first secondary side wiring respectively; The first switch, the second switch, and the output capacitor of the first circuit board are arranged on the same surface of the first circuit board, and the first secondary-side trace and the second secondary-side trace of the first circuit board are respectively arranged on at least any two layers of the first circuit board; and The first switch, the second switch and the output capacitor of the second circuit board are arranged on the same surface of the second circuit board, and the first secondary side trace and the second secondary side trace of the second circuit board are respectively arranged on at least any two layers of the second circuit board.

13. The resonant converter according to claim 10 , wherein the first circuit board and the second circuit board respectively comprise two first switches and two second switches, and the output capacitor is multiple, and the two secondary-side traces respectively comprise: two first secondary-side traces electrically connecting the two first switches of the first circuit board and the two first switches of the second circuit board respectively; and Two second-second-side traces, one electrically connecting the second second switch of the first circuit board and one of the two first-second-side traces, and the other electrically connecting the second second switch of the second circuit board and the other of the two first-second-side traces; The two first switches, the two second switches and the plurality of output capacitors of the first circuit board are respectively arranged on two surfaces of the first circuit board, and the first secondary-side traces and the second secondary-side traces of the first circuit board are respectively arranged on at least any four layers of the first circuit board; and The two first switches, the two second switches and the plurality of output capacitors of the second circuit board are respectively arranged on two surfaces of the second circuit board, and the first secondary side traces and the second secondary side traces of the second circuit board are respectively arranged on at least any four layers of the second circuit board.

14. The resonant converter as claimed in claim 10, wherein the output capacitor is multiple, and the two secondary-side circuits further respectively comprise: a third switch and a fourth switch; The first switch, the second switch, and one of the plurality of output capacitors of the first circuit board are disposed on one surface of the first circuit board, and the third switch, the fourth switch, and another of the plurality of output capacitors of the first circuit board are disposed on another surface of the first circuit board, and the secondary-side traces of the first circuit board are disposed on at least any two layers of the circuit board; and The first switch, the second switch, and one of the plurality of output capacitors of the second circuit board are arranged on one surface of the first circuit board, and the third switch, the fourth switch, and another of the plurality of output capacitors of the second circuit board are arranged on another surface of the second circuit board, and the secondary side traces of the second circuit board are arranged on at least any two layers of the circuit board.

15. The resonant converter of claim 10 , wherein when the first switch is turned on, a first current flows from the first switch around the through-hole to the output capacitor to form a first current path, and when the second switch is turned on, a second current flows from the second switch around the through-hole to the output capacitor to form a second current path, wherein the first current path and the second current path have opposite directions.

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