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 formed around the first circuit board through hole and the second circuit board through hole respectively, and the first conductive columns are electrically connected with the wires arranged around the first circuit board through hole and the wires arranged around the second circuit board through hole to form a winding of the flat plate type transformer. The iron core is used for sleeving the windings of the first circuit board and the second circuit board to form a 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, resonant converters typically incorporate multiple power components (e.g., power switches, output capacitors, drivers), resonant inductors, and transformers onto a single circuit board. These components are then connected using routing software. Because the resonant converter's transformer utilizes planar technology, the transformer is formed on the single circuit board. When current flows through the single circuit board, the circuit board must withstand high currents, potentially leading to excessive heat accumulation and poor heat dissipation efficiency, hindering further efficiency improvements in the resonant converter. Summary of the Invention

[0005] 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.

[0006] 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 flat-plate transformer. The flat-plate transformer includes a first circuit board through-hole, a second circuit board through-hole, an iron core, a plurality of traces, and a first conductive post. The primary-side circuit is disposed on the first circuit board, and the secondary-side circuit is disposed on the first and second circuit boards, respectively. The flat-plate transformer is disposed on the first and second circuit boards and electrically connects the primary-side circuit and the secondary-side circuit. The first and second circuit board through-holes extend through the first and second circuit boards, respectively, and the iron core includes a first iron core post extending through the first and second circuit board through-holes. Traces are formed around the first and second circuit board through-holes, respectively, and a first conductive post is disposed between the first and second circuit boards. The first conductive post electrically connects the traces disposed around the first circuit board through-hole and the traces disposed around the second circuit board through-hole to form the windings of the flat-plate transformer. The iron core is used to encase the windings of the first and second circuit boards to form the flat-plate transformer.

[0007] The purpose and effect of the present disclosure is to realize a resonant converter using a two-circuit-circuit-circuit-type physical structure, with a single iron core encased in a winding formed by conductive posts electrically connecting the two circuit board traces, resulting in a four-sided structure. This allows for evenly dissipating heat, effectively increasing the heat dissipation area, and thereby improving circuit efficiency.

[0008] 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

[0009] Figure 1A schematic diagram of the internal circuit arrangement of a conventional power supply;

[0010] 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;

[0011] Figure 3A is a circuit diagram of a first embodiment of a resonant converter disclosed herein;

[0012] Figure 3B is a circuit diagram of a second embodiment of a resonant converter disclosed herein;

[0013] Figure 3C is a circuit diagram of a third embodiment of a resonant converter disclosed herein;

[0014] Figure 4A A first perspective view of the three-dimensional circuit structure assembly of the second embodiment of the resonant converter disclosed herein;

[0015] Figure 4B A second perspective view of the three-dimensional circuit structure assembly of the second embodiment of the resonant converter disclosed herein;

[0016] Figure 4C A third perspective view of the three-dimensional circuit structure assembly of the second embodiment of the resonant converter disclosed herein;

[0017] Figure 4D This is an exploded view of the three-dimensional circuit structure of the second embodiment of the resonant converter disclosed herein;

[0018] Figure 5A A wiring structure diagram of one surface layer of the second circuit board of the second embodiment;

[0019] Figure 5B A wiring structure diagram of another surface layer of the second circuit board of the second embodiment;

[0020] Figure 6A A wiring structure diagram of one surface layer of the second circuit board of the second embodiment;

[0021] Figure 6B A wiring structure diagram of another surface layer of the second circuit board of the second embodiment;

[0022] 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;

[0023] 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;

[0024] Figure 9AFor 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

[0025] 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;

[0026] Figure 10A A diagram showing the winding arrangement of the toroidal transformer disclosed herein;

[0027] Figure 10B A perspective view of the wiring layout of the first and second embodiments of the toroidal transformer disclosed herein;

[0028] Figure 10C A comparison diagram of the routing of the present disclosure set at different staggered angles;

[0029] Figure 10D The impedance curve diagram of the present disclosure at different routing angles;

[0030] Figure 11A It is the magnetic flux distribution diagram of the wiring disclosed in the present invention;

[0031] Figure 11B A schematic diagram of magnetic flux cancellation in the first embodiment of the present disclosure with staggered routing;

[0032] Figure 11C A schematic diagram of magnetic flux cancellation in a second embodiment of the present disclosure with staggered routing;

[0033] Figure 12A A perspective view of the wiring disclosed herein formed in a winding area;

[0034] Figure 12B For this disclosure Figure 12A Schematic diagram of magnetic flux cancellation after enlarging areas A4 and A5;

[0035] Figure 12C A comparison diagram of the routing of the present disclosure with different widths in the same winding area;

[0036] Figure 12D The impedance curve diagram of the present disclosure is set at different widths under the same winding area;

[0037] Figure 13A Schematic diagram of the wiring arrangement of the flat-plate transformer disclosed in the present invention;

[0038] Figure 13B A perspective plan view of the wiring structure of the flat-plate transformer disclosed herein;

[0039] Figure 13C A three-dimensional perspective view of the wiring structure of the flat-plate transformer disclosed herein;

[0040] Figure 14A A schematic diagram of a secondary side wiring extension using staggered routing in the first embodiment of the present disclosure;

[0041] Figure 14B A schematic diagram of a secondary side wiring extension using staggered routing in the second embodiment of the present disclosure; and

[0042] Figure 15 This is a structural diagram of the secondary side routing using staggered laying.

[0043] The reference numerals are as follows:

[0044] PSU: Power Supply Unit

[0045] CT_I: Input circuit

[0046] IN_AC: power input terminal

[0047] EMI: Electromagnetic Interference Filter

[0048] PFC: Power Factor Corrector

[0049] Cap_B: DC bus capacitor

[0050] CM_I: Integrated power conversion module

[0051] MCU: system control circuit

[0052] AUX: Auxiliary power circuit

[0053] CT_O: output circuit

[0054] Fan: fan

[0055] SE: Space

[0056] 100: Resonant Converter

[0057] 100A: Resonant conversion circuit

[0058] CB1, CB2: circuit boards

[0059] Via_A~Via_C, Via_E~Via_H: irrigation holes

[0060] LA, LA1-1~LA1-8, LA2-1~LA2-8: sub-layer board

[0061] IN: Input terminal

[0062] OUT: output terminal

[0063] SG:Signal transmission end

[0064] 1A: Primary side circuit

[0065] SP_1: Primary side switch bridge arm

[0066] Q1, Q2: power switches

[0067] Lr: resonant inductor

[0068] CL: Inductor core

[0069] HL1, HL2: Inductor perforation

[0070] Lc: Inductor winding

[0071] Tl-1, Tl-2: Inductor routing

[0072] Cr: resonant capacitor

[0073] 2A, 2B: Transformer

[0074] PE: Flat type transformer

[0075] CB1_H: First circuit board perforation

[0076] CB2_H: Second circuit board through hole

[0077] H1, H2, H3, H4, H: Perforated

[0078] D1: First direction

[0079] D2: Second direction

[0080] C1, C2: iron core

[0081] C1_1, C1_2, CL_1, CL_2: Cover

[0082] C1_3, CL_3: side

[0083] C1_4, CL_4: accommodating groove

[0084] C12: First core column

[0085] C14: Second core column

[0086] GP: Air Gap

[0087] 22: Winding

[0088] T_1~T_n, T_(n), T_(m), T_1(n)~T_n(n), T_1(m)~T_n(m): routing DW_1, DW_2: extension direction

[0089] θ: angle

[0090] DC_R: DC resistance

[0091] AC_R: AC impedance

[0092] T_R: total impedance

[0093] RS_1, RS_2: Range

[0094] Fi, Fo: magnetic flux

[0095] Fi_t, Fo_t: total magnetic flux

[0096] A1~A6: Area

[0097] AS_1~AS_3: Winding area

[0098] 22A: Primary side winding

[0099] Tp-1, Tp-2: primary side wiring

[0100] 22B: Secondary winding

[0101] Ts-1, Ts-2, Ts-1_1~Ts-1_n: Secondary side wiring

[0102] 22B-1: First winding

[0103] Ts1-1, Ts1-2, Ts1-1_(n), Ts1-2_(m): first secondary side trace 22B-2: second winding

[0104] Ts2-1, Ts2-2, Ts2-1_(n), Ts2-2_(m): Second secondary side wiring SI_1, SI_2: Insulation section

[0105] PC_1, PC_2: conductive columns

[0106] PC: Pillar

[0107] MMF: Magnetomotive force

[0108] M0: magnetic flux origin

[0109] M1: first predetermined offset

[0110] Mr: second predetermined offset

[0111] F_D1: first direction flux

[0112] F_D2: Second direction magnetic flux

[0113] CF1, CF2: magnetomotive force curves

[0114] 3A: Secondary side circuit

[0115] 32: Rectifier circuit

[0116] SS_1, SS_2: Secondary side switch bridge arms

[0117] SR1, SR2, SR3, SR4: switches

[0118] Co: output capacitance

[0119] 4A: Controller

[0120] DC / DC: DC conversion circuit

[0121] 300: Load

[0122] Pac: AC power supply

[0123] Pdc: DC power supply

[0124] Po: output power

[0125] Paux: Auxiliary power

[0126] I1, I2: current DETAILED DESCRIPTION

[0127] The technical content and detailed description of the present invention are now described as follows with reference to the accompanying drawings:

[0128] See also Figure 2The 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.

[0129] 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).

[0130] 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.

[0131] 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.

[0132] For reference Figure 3A-3BThe 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.

[0133] 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.

[0134] 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 4BMainly, the circuit of the resonant converter 100 (for example: Figure 3A to Figure 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.

[0135] 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.

[0136] 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 .

[0137] 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, which 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 traces, and the second circuit board CB2 includes another portion of the transformer 2A winding 22 formed by traces, these portions of the winding 22 can be electrically connected together via the conductive post PC_1 to form a complete winding 22A. 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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 CB1 and CB2. 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.

[0145] 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.

[0146] 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 first circuit board CB1 shown may 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.

[0147] 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.

[0148] 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, some 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 appropriate 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, transistors made of GaN material, 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.

[0149] 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 ).

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] exist Figures 7A and 7B 、 Figure 7G to Figure 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.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] See also Figure 10A This is a diagram showing the winding arrangement of the toroidal transformer disclosed herein. Figure 10A In the (a) diagram, the winding 22 of the transformer 2A is arranged in a ring-shaped space and is copper-plated in a whole piece. Its structure is similar to Figures 7A to 7H 、 Figures 8A to 8H , the primary side traces Tp-1, Tp-2, and the secondary side traces Ts-1, Ts-2 of each sub-layer board LA1 to LA8 of the first circuit board CB1 and the second circuit board CB2 are laid with an integrally formed copper foil in the extension direction of the traces. In one embodiment, if the winding 22 is not specifically specified, it can be the primary side winding 22A and / or the secondary side winding 22B of the first circuit board CB1 or the second circuit board CB2. Since the copper foil is extended in an integrally formed manner, the winding 22 in the (a) small figure has a lower DC impedance. Figure 10A In panel (b), the windings 22 (e.g., primary winding 22A or secondary winding 22B) of each sub-layer LA1-LA8 of the first and second circuit boards CB1 and CB2 form a structure with multiple parallel, oriented wiring. The wiring between each layer (e.g., primary wiring Tp or secondary wiring Ts) is arranged in an overlapping, staggered arrangement. This structure of multiple parallel, oriented wiring is similar to litz wire (commonly known as stranded wire), primarily using multiple insulated conductors wound around each other. The characteristic of the wiring structure shown in panel (b) of 10A is that it effectively reduces AC impedance. This can be particularly effective in applications where the resonant converter 100 is used for high-frequency switching, significantly reducing AC impedance.

[0163] See also Figure 10B Schematic diagram of the wiring layout of the first and second embodiments of the toroidal transformer of the present disclosure. Figure 10BThe diagram shows two sub-layer boards LA1 and LA2, with multiple vias (Via_C) located around the periphery of the winding area where the winding 22 is located. The vias (Via_C) are used to electrically connect the first sub-layer board LA1 and the second sub-layer board LA2, and traces T_1 to T_3 are formed around the through-hole H. Trace T_1 is used as an example, and (n) and (m) represent sub-layer boards LA1 and LA2 on different layers, respectively. Trace T_1(n) of the first sub-layer board LA1 extends from the periphery of the winding area where the winding 22 is located to the vias (Via_C) located around the through-hole H, and is electrically connected to the second sub-layer board LA2 via the vias (Via_C). Trace T_1(m) of the second sub-layer board LA2 extends from the vias (Via_C) to the vias (Via_C) located around the periphery of the winding area where the winding 22 is located, and is then electrically connected to the first sub-layer board LA1 via the vias (Via_C). Through vias (Via_C), traces T_1-T_3 can be staggered across the first and second sub-layers LA1 and LA2. Once the entire routing area is fully filled, traces T_1-T_3 on the same layer are arranged parallel to each other. Traces T_1(n)-T_3(n) on the first sub-layer LA1 can overlap traces T_1(m)-T_3(m) on the second sub-layer LA2, forming a staggered arrangement.

[0164] For reference Figure 10C This is a comparison diagram of the wiring of the present invention set at different staggered angles. Figure 10C In the embodiment, a plurality of traces T_1 to T_n are arranged in an overlapping and staggered manner. Taking trace T_1 as an example, trace T_1(n) of the first sub-layer board LA1 and trace T_1(m) of the second sub-layer board LA2 form an acute angle (angle θ is less than 90 degrees) with the via Via_C as the center, and the angle θ refers to the angle between trace T_1(n) of the first sub-layer board LA1 and trace T_1(m) of the second sub-layer board LA2. Figure 10C In the (a) diagram, the angle θ of the traces T_1(n) and T_1(m) is 45 degrees, and Figure 10C In the (b) panel, the angle θ of the traces T_1(n) and T_1(m) is 30 degrees.

[0165] For reference Figure 10D This is the impedance curve diagram of the present invention at different routing angles. Figure 10C In the (a) panel, when the angle θ of traces T_1(n) and T_1(m) is 45 degrees, the measured DC resistance DC_R is 20m ohms, and the AC resistance AC_R is 5.4m ohms. The total resistance T_R is approximately 23.5m ohms. Figure 10CIn panel (b), when the angle θ between traces T_1(n) and T_1(m) is 30 degrees, the measured DC resistance (DC_R) is 14.2mΩ, and the AC resistance (AC_R) is 8.8mΩ, resulting in a total impedance (T_R) of approximately 16.5mΩ. Therefore, when the angle θ between traces T_1(n) and T_1(m) is 30 degrees, the total impedance (T_R) is low. When the angle θ is within the range RS_1 between 25 and 30 degrees, the AC resistance (AC_R) is not excessively high, and the total impedance (T_R) is lower on the curve, representing a preferred embodiment.

[0166] See also Figure 11A This is the magnetic flux distribution diagram of the wiring disclosed in this invention. Figure 11A In the small figure (a), the direction of the arrow indicates the extension direction of the trace T_(n) of the first sub-layer board LA1, and when the current flows in the direction of the arrow, magnetic fluxes Fi and Fo are generated on both sides of the arrow (in this embodiment, i and o represent the directions of entry and exit). Figure 11A In panel (b), the arrows indicate the extension direction of trace T_(m) on the second sub-layer LA2. When current flows in the arrowed direction, magnetic fluxes Fi and Fo are generated on both sides of the arrows. Because the extension directions of panels (a) and (b) intersect, the directions of the magnetic fluxes Fi and Fo are opposite.

[0167] For reference Figure 11B This is a schematic diagram of flux cancellation in the first embodiment of the present invention with staggered routing. When the first sub-layer board LA1 and the second sub-layer board LA2 are stacked together, the magnetic fluxes Fi and Fo of the two layers overlap, generating total magnetic fluxes Fi_t and Fo_t. The total magnetic fluxes Fi_t and Fo_t in regions A1 and A2 cancel each other out because the magnetic fluxes Fi and Fo in panels (a) and (b) are in opposite directions. This results in smaller total magnetic fluxes Fi_t and Fo_t in regions A1 and A2 (indicated by smaller circles). In the other two regions, the opposite occurs, resulting in larger total magnetic fluxes Fi_t and Fo_t (indicated by larger circles).

[0168] For reference Figure 11C Schematic diagram of magnetic flux cancellation in the second embodiment of the present disclosure with staggered routing. Figure 11C Mainly Figure 11B The structures are arranged side by side, and the traces T_1(n) and T_2(m) are set on different sub-layer boards LA1 and LA2, and the traces T_1(m) and T_2(n) are also set on different sub-layer boards LA1 and LA2. The traces T_1(n) and T_2(m) are arranged side by side with T_1(m) and T_2(n), and are connected to the different sub-layer boards LA1 and LA2 through vias (not shown) to form area A3. Area A3 can be mainly regarded as Figure 11BThe total magnetic fluxes Fi_t and Fo_t of the two areas A1 and A2 overlap, and their total magnetic fluxes Fi_t and Fo_t are offset because their directions are positive and negative, making the total magnetic fluxes Fi_t and Fo_t in area A3 smaller, and the total magnetic fluxes Fi_t and Fo_t in the remaining areas larger due to the superposition of magnetic fluxes.

[0169] See also Figure 12A FIG. 4 is a perspective view of the wiring of the present disclosure formed in the wiring area. Figure 12A The second sub-layer board LA1 and LA2 are also used as an example, and a plurality of vias (not shown) electrically connecting the first sub-layer board LA1 and the second sub-layer board LA2 are formed around the winding area AS_1 where the traces T_1 to T_n are set. Figure 12A The principle is similar to Figure 11C , mainly utilizes the staggered routing structure to achieve the effect of magnetic flux cancellation, and expands its application range to the entire winding area AS_1.

[0170] For reference Figure 12B For this disclosure Figure 12A Schematic diagram of magnetic flux cancellation after enlarging areas A4 and A5. Figure 12B The (a) sub-figure mainly shows Figure 12A The wiring structure of area A4 is shown in Figure 1. The wiring on the first sub-layer board LA1 is sequentially T_1(n) to T_3(n), and the wiring on the second sub-layer board LA2 is sequentially T_4(m) to T_6(m). Figure 11B Therefore, the entire area A4 is like Figure 11B In the areas A1 and A2, there is a magnetic flux cancellation effect. Figure 12B The (b) sub-figure mainly shows Figure 12A The routing structure of area A5 is shown in Figure 1. The routing on the first sub-layer LA1 is sequentially T_7(n) to T_9(n). The routing on the second sub-layer LA2 is sequentially T_8(m) to T_10(m), and routing T_9(m) is an extension of routing T_9(n) through a via, belonging to the same path. Since the surrounding areas of area A5, except for area A6, are similar, Figure 11B Therefore, except for area A6, the rest of area A5 is the same as Figure 11B The areas A1 and A2 also have the effect of magnetic flux cancellation. Figure 12B See also the characteristics of Figure 12A Except for the periphery of the winding area AS_1 which has the same structure as the area A6 and does not have the magnetic flux cancellation effect, the rest of the winding area AS_1 has the magnetic flux cancellation effect, thereby achieving the effect of reducing the core loss and copper wire loss.

[0171] See also Figure 12CThis is a comparison diagram of the wiring disclosed in the present invention with different widths set in the same winding area. Figure 12C In the embodiment, the plurality of traces T_1 to T_18 are arranged in a staggered manner in an overlapping manner within the same winding area AS_2. Figure 12C In the (a) panel, the traces T_1 to T_10 are wider and 10 traces T_1 to T_10 are formed in the routing area AS_2. Figure 12C In panel (b), traces T_1-T_18 are narrow, resulting in 18 traces T_1-T_18 within the routing area AS_2. When traces T_1-T_10 are wider, the DC impedance is lower, but the AC impedance is higher. The opposite is true when the traces are narrower. Therefore, adjusting the width of traces T_1-T_18 affects the number of traces T_1-T_8 and can simultaneously adjust both the AC and DC impedances. Another factor affecting AC impedance is the distance between traces T_1-T_18. When the distance between traces T_1-T_18 is closer, the AC impedance is lower, and vice versa. Therefore, within the routing area AS_2, adjusting the distance and width of traces T_1-T_18 can effectively reduce the AC impedance. If the AC impedance allows, the DC impedance can be improved by increasing the width of traces T_1-T_18.

[0172] For reference Figure 12D This is the impedance curve diagram of the present invention under the same winding area with different width settings. Figure 12C The (a) panel includes 10 traces T_1 to T_10 that are wider than those in the (b) panel, and the distance between traces T_1 to T_18 is greater. The measured AC impedance AC_R and DC impedance DC_R are 9.4m ohms and 10m ohms respectively, and the total impedance T_R is approximately 18m ohms. Figure 12C Panel (b) includes 18 narrower traces T_1-T_18 than those in panel (a), and the distance between traces T_1-T_18 is closer. The measured AC impedance AC_R and DC impedance DC_R are 6.8mΩ and 11mΩ, respectively, converting to a total impedance T_R of approximately 16mΩ. Therefore, within the same routing area AS_2, when the number of traces T_1-T_18 falls within the range RS_2 of 16-18, the AC impedance AC_R is not excessively high, and the total impedance T_R is located lower on the curve, indicating a preferred implementation.

[0173] See also Figure 13A This is a schematic diagram of the wiring arrangement of the flat-plate transformer disclosed in the present invention. Figure 13A In the embodiment of the flat transformer PE, the winding 22 formed by the first circuit board CB1 and the second circuit board CB2 is mainly used for Figures 10A to 12DThe first and second circuit boards CB1 and CB2 each include a plurality of vias (Via_C) for electrically connecting the first and second sub-layer boards LA1-1 and LA1-2. The vias (Via_C) are formed around the periphery of the winding area AS_3 and the peripheries of the through-holes H1 and H2. The planar transformer PE also includes a plurality of traces T_1 to T_n, which are formed in the winding area AS_3.

[0174] At Figure 13A In the embodiment, the solid arrow represents the extension direction DW_1 of the trace T_1(n) of the first sub-layer board LA1-1, and the dotted arrow represents the extension direction DW_2 of the trace T_1(m) of the second sub-layer board LA1-2, and the extension directions DW_1 and DW_2 are connected head to tail; in order to briefly and clearly illustrate the setting method of the winding 22, only a single trace T_1(n) and T_1(m) of the single-piece circuit boards CB1 and CB2 are shown for illustration. At the head of the arrow, trace T_1(n) of the first sub-layer LA1-1 extends from the arrow's extension direction DW_1 to the via hole Via_C at the periphery of the routing area AS_3, and then extends through the via hole Via_C to the second sub-layer LA1-2, and then continues from the extension direction DW_2 to the via hole Via_C at the periphery of the first through-hole H1. This process is repeated and interlaced in the first sub-layer LA1-1 and the second sub-layer LA1-2 until the tail end of the arrow. Figure 13B This is a perspective plan view of the wiring structure of the flat-plate transformer disclosed herein. Traces T_2-T_n are arranged parallel to trace T_1 and wind around the entire winding area AS_3, forming a partial winding 22 comprised of multiple traces T_1-T_n. Conductive pillars PC_1 electrically connect the two circuit boards CB1 and CB2 to form a complete winding 22. In one embodiment, since vias Via_C are formed around the perimeter of the winding area AS_3 and the perimeters of the through-holes H1 and H2, copper casting can be used on the circuit board side.

[0175] In this embodiment, the angles θ of the traces T_(n) and T_(m) at both ends of the via_C can be combined with the reference Figures 10A to 10D Adjust the width of the traces T_1 to T_n and the distance between the traces T_1 to T_n. Figures 12A to 12D In this embodiment, the sub-layer boards LA1-1 and LA1-2 of the circuit boards CB1 and CB2 are the layers for setting the secondary side winding 22B. Therefore, the traces T_1 to T_n are multiple secondary side traces Ts-1_1 to Ts-1_n (taking the first circuit board CB1 as an example) to electrically connect the secondary side winding 22B of the secondary side circuit 3A. Figures 7A and 7B 、 Figures 7G to 7H 、 Figures 8A and 8B 、 Figures 8G to 8H , Figure 13B The staggered secondary side traces Ts-1_1~Ts-1_n can replace the first secondary side traces Ts1-1, Ts1-2 or the second secondary side traces Ts2-1, Ts2-2, and apply Figures 10A to 12D The angle θ, line width and line spacing are set by the technology, and Figures 7C to 7F 、 Figures 8C to 8F The primary side traces Tp-1 and Tp-2 can be applied or not. Figures 10A to 12D 、 Figures 13A and 13B The staggered routing setting technology can be set according to the level of AC impedance AC_R and the uniformity of magnetic flux.

[0176] In other embodiments, Figures 7C to 7F 、 Figures 8C to 8F The primary side traces Tp-1 and Tp-2 can also be used Figure 13B The staggered arrangement of the traces T_1 to T_n (not shown) is applied. Figures 10A to 12D The angle θ, line width and line spacing are set by the technology, and Figures 7A-7B The first secondary side traces Ts1-1, Ts1-2 or the second secondary side traces Ts2-1, Ts2-2 of 7G~7H, 8A~8B, 8G~8H can be applied or not. Figures 10A to 12D 、 Figures 13A and 13B The arrangement can be performed by staggered arrangement of the wiring, which can be determined according to the level of the AC impedance AC_R and the uniformity of the magnetic flux. In another embodiment, Figure 7F 、 Figure 8F The inductor traces Tl-1 and Tl-2 can also be used selectively Figure 13B The staggered arrangement of the traces T_1 to T_n (not shown) is applied. Figures 10A to 12D The angle θ, line width and line spacing are set using the technology.

[0177] For reference Figure 13CThis is a perspective view of the wiring structure of the flat-plate transformer disclosed herein. The flat-plate transformer PE includes sub-layers LA1-1 and LA1-2, which are used to mount secondary-side trace Ts-1 on circuit boards CB1 and CB2 (using the first circuit board CB1 as an example). The sub-layers LA1-1 and LA1-2 further include insulating segments SI_1 and SI_2 extending from through-holes H1 and H2 to the periphery of the winding area AS_3. These insulating segments SI_1 and SI_2 prevent traces Ts-1_1 through Ts-1_n from extending in directions DW_1 and DW_2, encircling through-holes H1 and H2, and then electrically connecting to traces Ts-1_1 through Ts-1_n at the arrowheads, potentially short-circuiting winding 22 when currents I1 and I2 flow through them. The perimeters of the insulating segments SI_1 and SI_2 also include multiple vias (Via_C). These vias allow traces Ts-1_1 through Ts-1_n to extend alternately between the first and second sub-layer boards LA1-1 and LA1-2. The size of the winding area AS_3 is primarily determined by the slots C1_4 that accommodate the windings 22 of the transformer 2A. A larger slot C1_4 increases the size of the winding area AS_3, and vice versa. Because the side portion C1_3 of the core C1 is located on the outer side of the first circuit board CB1, an air gap GP is formed. Therefore, at least one side of the winding area AS_3 can be formed on the outer side of the first circuit board CB1 in coordination with the core C1.

[0178] See also Figure 14A This is a schematic diagram of the secondary side wiring using staggered routing in the first embodiment of the present disclosure. Figure 14A In this embodiment (taking the first circuit board CB1 as an example), the first secondary-side trace Ts1-1_(n), which forms part of the first winding 22B-1, extends away from the first switch SR1 to the first secondary-side trace Ts1-1_(m) on another layer. The same applies to the second secondary-side traces Ts2-1_(n) and Ts2-1_(m), which form part of the second winding 22B-2. The difference is that the second secondary-side traces Ts2-1_(n) and Ts2-1_(m) are laid in the opposite direction of the first secondary-side traces Ts1-1_(n) and Ts1-1_(m), forming an interleaving arrangement. In this embodiment, the two circuit boards CB1 and CB2 include a first via Via_E, a second via Via_F, a third via Via_G, and a fourth via Via_H, respectively. The first via Via_E and the second via Via_F are respectively formed on a first side and a second side opposite to the first side of the first through-hole H1, and are used to electrically connect the first sub-layer board LA1-1 and the second sub-layer board LA1-2 of the first circuit board CB1.

[0179] The third via Via_G and the fourth via Via_H are formed on a first side and a second side opposite the first side of the first through-hole H1, respectively. The third via Via_G and the fourth via Via_H are used to electrically connect the first sub-layer LA1-1 and the second sub-layer LA1-2 of the first circuit board CB1. In this embodiment, the second side is the side closest to the output terminal OUT, while the first side is located on the other side of the first through-hole H1. The first switch SR1, the second switch SR2, and the output capacitor Co are disposed on the second side. In one embodiment, the configuration of the second circuit board CB2 is identical to that of the first circuit board CB1 and will not be further described here.

[0180] like Figure 14A As shown in sub-figure (a), and taking the first circuit board CB1 as an example, the first secondary-side trace Ts1-1_(n) can be located on the first sub-layer board LA1-1 and electrically connected to the first switch SR1. The first secondary-side trace Ts1-1_(n) extends from the first sub-layer board LA1-1 in a first direction D1 surrounding the first through-hole H1 to the first via Via_E, and then extends through the first via Via_E to the second sub-layer board LA1-2. Figure 14A As shown in the small figure (b), the first secondary side trace Ts1-1_(m) extending to the second sub-layer board LA1-2 continues the first direction D1 and extends to the second side to be electrically connected to the output capacitor Co through the second via Via_F.

[0181] The second secondary-side trace Ts2-1_(n) can be located on the first sub-layer LA1-1 and electrically connected to the second switch SR2. The second secondary-side trace Ts2-1_(n) extends from the first sub-layer LA1-1 in the second direction D2, surrounding the first through-hole H1, to the third via Via_G, and then extends to the second sub-layer LA1-2 through the third via Via_G. The second secondary-side trace Ts2-1_(m) extending to the second sub-layer LA1-2 continues in the second direction D2 to the second side, and is electrically connected to the output capacitor Co through the fourth via Via_H. Figure 14A In panels (a) and (b), the first switch SR1 and the second switch SR2 are respectively arranged on opposite sides of the second via Via_F (fourth via Via_H), and the first direction D1 and the second direction D2 are in opposite directions along the first through-hole H1 to form a ring-shaped staggered routing structure.

[0182] See also Figure 14B This is a schematic diagram of the secondary side wiring using staggered routing in the second embodiment of the present disclosure. Figure 14BIn the embodiment (taking the first circuit board CB1 as an example), the first via Via_E and the second via Via_F are respectively formed on the third side and the fourth side opposite to the third side of the second through hole H2, and the first via Via_E and the second via Via_F are used to electrically connect the first sub-layer board LA1-1 and the second sub-layer board LA1-2 of the first circuit board CB1. Figure 14A The first side of the circuit board CB2 can be the same side, and the fourth side and the second side can be the same side, the only difference being that the first through-hole H1 and the second through-hole H2 are located at different positions. In one embodiment, the configuration of the second circuit board CB2 is the same as that of the first circuit board CB1, and will not be further described here.

[0183] For reference Figure 14B As shown in panels (a) and (b) of FIG1 , and taking the first circuit board CB1 as an example, a first secondary-side trace Ts1-1_(n) extends from the first sub-layer LA1-1 in the second direction D2, encircling the second through-hole H2, to the first via Via_E, and then extends to the second sub-layer LA1-2 through the first via Via_E. The first secondary-side trace Ts1-1_(m) extending to the second sub-layer LA1-2 continues in the second direction D2 to the fourth side, and is electrically connected to the output capacitor Co through the second via Via_F.

[0184] The second secondary-side trace Ts2-1_(n) extends from the first sub-layer LA1-1 in the first direction D1, encircling the second through-hole H2, to the third via Via_G. It then extends to the second sub-layer LA1-2 through the third via Via_G. The second secondary-side trace Ts2-1_(m) extending to the second sub-layer LA1-2 continues in the first direction D1 to the fourth side, electrically connecting to the output capacitor Co through the fourth via Via_H. Figure 14B and Figure 14A Another difference is that the first secondary-side traces Ts1-1_(n), Ts1-1_(m) and the second secondary-side traces Ts2-1_(n), Ts2-1_(m) are located at opposite positions on the left and right, and extend in opposite directions.

[0185] pass Figure 14A 、 Figure 14B By employing a loop-shaped, staggered routing structure, the current paths of the first secondary-side routing lines Ts1-1_(n) and Ts1-1_(m) and the second secondary-side routing lines Ts2-1_(n) and Ts2-1_(m) are precisely opposite in direction. Furthermore, the loop-shaped current paths form the shortest current path. This achieves magnetic flux cancellation and reduces the AC impedance AC_R of the secondary-side circuit 3A, thereby improving the efficiency of the resonant converter 100.

[0186] For reference Figure 15The secondary side wiring of this disclosure uses a staggered layout. Figures 7A and 7B 、 Figures 7G to 7H 、 Figures 8A and 8B 、 Figures 8G to 8H In the figure, since the secondary side trace Ts-1 and the first through hole H1 and the second through hole H2 form an M-shaped trace, and the secondary side trace Ts-2 and the third through hole H3 and the fourth through hole H4 form an M-shaped trace, it is possible to Figure 14A 、 Figure 14B The staggered laying of the wiring extension is integrated together to form Figure 15 As shown in the small figure 15(a), and taking the first circuit board CB1 as an example, when the two sides of the m-shaped trace are the first secondary traces Ts1-1_(n), Figure 14A 、 Figure 14B The two sets of second secondary side traces Ts2-1_(n) in the first direction D1 and the second direction D2 can be sandwiched between the first secondary side traces Ts1-1_(n). Figure 14A 、 Figure 14B The two sets of second-secondary side traces Ts2-1_(n) have the same properties, so they can be integrated into an integrated configuration. As shown in the small figure 15(b), when the two sides of the M-shaped trace are the second-secondary side traces Ts2-1_(n), Figure 14A 、 Figure 14B The two sets of first secondary traces Ts1-1_(n) in the first direction D1 and the second direction D2 can be sandwiched between the second secondary traces Ts2-1_(n), and thus can also be integrated into a single piece. The second circuit board CB2 has similar characteristics to the first circuit board CB1 and can also be integrated into a single piece.

[0187] In one embodiment, Figures 13A to 13C The staggered arrangement of the traces can be Figures 14A to 15 The staggered routing structure is applied in conjunction with the staggered routing structure. The staggered routing structure applies to at least one of the primary-side routings Tp-1 and Tp-2 and the secondary-side routings Ts-1 and Ts-2 on the two PCBs CB1 and CB2. Therefore, each PCB CB1 and CB2 requires at least two sub-layer boards, such as LA1-1 and LA1-2. The staggered routing structure applies to the secondary-side routings Ts-1 and Ts-2, so at least two sub-layer boards are required, such as LA1-3 and LA1-4. Therefore, if the two are used in combination, the structure of staggered routing and the structure of staggered routing require the use of four sub-layer boards LA1-1, LA1-2, LA1-3, and LA1-4, and an additional layer is used to set the primary side routing Tp-1, Tp-2 and the secondary side routing Ts-1, Ts-2, but the sub-layer board with staggered routing and staggered routing is not used, for example: LA1-5.

[0188] Taking the first circuit board CB1 as an example, assuming that the staggered routing structure is applied to the first secondary-side routing Ts1-1 and the second secondary-side routing Ts2-1, and that the staggered routing structure is also applied to the first secondary-side routing Ts1-1 and the second secondary-side routing Ts2-1: the first secondary-side routing Ts1-1 may extend staggeredly on the sub-layers LA1-1 and LA1-2. When the first secondary-side routing Ts1-1_(n) extends from the first sub-layer LA1-1 to the first via hole Via_E, it extends from the first via hole Via_E to the third sub-layer LA1-3 and then extends staggeredly along the first direction D1 to the second side. When the first secondary-side routing Ts1-1_(m) extends from the second sub-layer LA1-2 to the first via hole Via_E, it extends from the first via hole Via_E to the fourth sub-layer LA1-4 and then extends staggeredly along the first direction D1 to the second side.

[0189] When the second secondary-side trace Ts2-1_(n) extends from the first sub-layer LA1-1 to the third via_G, it extends from the third via_G to the third sub-layer LA1-3, and then extends in a staggered manner along the second direction D2 to the second side. When the second secondary-side trace Ts2-1_(m) extends from the second sub-layer LA1-2 to the third via_G, it extends from the third via_G to the fourth sub-layer LA1-4, and then extends in a staggered manner along the second direction D2 to the second side.

[0190] 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; a primary-side circuit, disposed on the first circuit board; A secondary side circuit is respectively provided on the first circuit board and the second circuit board; 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; 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 of claim 1 , wherein the planar transformer further comprises: A plurality of vias, respectively used to electrically connect a first sub-layer board and a second sub-layer board of the first circuit board and the second circuit board; Wherein, the plurality of routing lines respectively extend through the plurality of filling holes in an alternating manner on the first sub-layer board and the second sub-layer board, and the routing lines on the same layer are arranged in parallel.

3. The resonant converter of claim 2 , wherein the first circuit board through-hole comprises: A first through hole and a second through hole pass through the first circuit board; The second circuit board through-hole comprises: A third through hole and a fourth through hole pass through the second circuit board, and the first core column passes through the first through hole and the third through hole; The iron core further includes a second iron core column passing through the second through-hole and the fourth through-hole, and the plurality of wirings are respectively formed around the first through-hole, the second through-hole, the third through-hole and the fourth through-hole.

4. The resonant converter of claim 2 , wherein the plurality of traces are a plurality of secondary-side traces serving as a secondary-side winding electrically connected to a secondary-side circuit, and the planar transformer further comprises: Two primary-side traces are formed on the first circuit board and a third sub-layer board of the second circuit board respectively; A second conductive column is disposed between the first circuit board and the second circuit board and electrically connected to the two primary-side traces to form a primary-side winding of the flat-plate transformer.

5. The resonant converter of claim 4 , wherein the first circuit board through-hole comprises a first through-hole, the second circuit board through-hole comprises a third through-hole, and the planar transformer further comprises: Two first vias are formed on a first side of the first through-hole and the third through-hole, respectively, and the two first vias are used to electrically connect the first sub-layer board and the fourth sub-layer board of the first circuit board and the second circuit board, respectively; Two second vias are formed on a second side opposite to the first side, and the two second vias are used to electrically connect the second sub-layer board and the fifth sub-layer board of the first circuit board and the second circuit board, respectively. The first switch, the second switch, and the output capacitor of the two secondary-side circuits are disposed on the second side. Two third filling holes are respectively formed on the first side, and the two third filling holes are used to electrically connect the first sub-layer board and the fourth sub-layer board respectively; and Two fourth filling holes are respectively formed on the second side, and the two fourth filling holes are used to electrically connect the second sub-layer board and the fifth sub-layer board respectively; The plurality of secondary-side traces include a plurality of first secondary-side traces and a plurality of second secondary-side traces, the plurality of first secondary-side traces are electrically connected to the first switches of the first circuit board and the second circuit board, respectively, and the plurality of second secondary-side traces are electrically connected to the plurality of first secondary-side traces and the second switches of the first circuit board and the second circuit board, respectively; The plurality of first secondary-side traces extend from the first sub-layer in a first direction surrounding the first through-hole and the third through-hole to the two first vias, respectively extend through the two first vias to the fourth sub-layer, and continue in the first direction to the second side, so as to electrically connect the output capacitors of the first circuit board and the second circuit board through the two second vias. The plurality of first secondary-side traces extend from the second sub-layer in a circumferential direction to the two first vias, respectively extend through the two first vias to the fifth sub-layer, and continue along the first direction to the second side, so as to electrically connect the output capacitors of the first circuit board and the second circuit board through the two second vias. wherein the plurality of second secondary-side traces extend from the first sub-layer in a second direction surrounding the first through-hole and the third through-hole to the two third vias, respectively extend through the two third vias to the fourth sub-layer, and continue in the second direction to the second side, so as to electrically connect the output capacitors of the first circuit board and the second circuit board through the two fourth vias; and The plurality of second-secondary-side traces extend from the second sub-layer board in a circumferential direction to the two third vias, respectively extend through the two third vias to the fifth sub-layer board, and continue in the second direction to the second side, so as to electrically connect the output capacitors of the first circuit board and the second circuit board through the two fourth vias respectively. The first direction and the second direction are opposite to each other along the first through hole, and the first direction and the second direction are opposite to each other along the third through hole.

6. The resonant converter of claim 2 , wherein the plurality of traces are a plurality of primary-side traces and are electrically connected via the first conductive post to serve as a primary-side winding electrically connected to the primary-side circuit, and the planar transformer further comprises: Secondary-side traces are formed on the first circuit board and the second circuit board respectively, and serve as secondary-side windings electrically connected to the secondary-side circuit.

7. The resonant converter of claim 2 , wherein the plurality of traces are formed in the winding areas of the first circuit board and the second circuit board, and the plurality of vias are formed around the winding areas, around the through-holes of the first circuit board, and around the through-holes of the second circuit board.

8. The resonant converter of claim 1 , wherein the two secondary-side circuits comprise a first switch, a second switch, and an output capacitor disposed on the first circuit board and the second circuit board, respectively, and one end of the output capacitor is electrically connected to one end of the first switch and one end of the second switch; the first circuit board through-hole comprises a first through-hole, and the second circuit board through-hole comprises a third through-hole; and the planar transformer comprises: Two first vias are formed on a first side of the first through-hole and the third through-hole, respectively, and the two first vias are used to electrically connect the first sub-layer board and the fourth sub-layer board of the first circuit board and the second circuit board, respectively; Two second vias are formed on a second side opposite to the first side, and the two second vias are used to electrically connect the second sub-layer board and the fifth sub-layer board of the first circuit board and the second circuit board, respectively. The first switch, the second switch, and the output capacitor of the two secondary-side circuits are disposed on the second side. Two third filling holes are respectively formed on the first side, and the two third filling holes are used to electrically connect the first sub-layer board and the fourth sub-layer board respectively; and Two fourth filling holes are respectively formed on the second side, and the two fourth filling holes are used to electrically connect the second sub-layer board and the fifth sub-layer board respectively; Wherein, the plurality of routings include two secondary-side routings, and two of the secondary-side routings respectively include a first secondary-side routing and a second secondary-side routing electrically connected to the first secondary-side routing, the first secondary-side routings of the two secondary-side routings are respectively electrically connected to the first switches of the first circuit board and the second circuit board, and the second secondary-side routings of the two secondary-side routings are respectively electrically connected to the second switches of the first circuit board and the second circuit board; wherein a first secondary-side trace of the two secondary-side traces extends from the first sub-layer in a first direction surrounding the first through-hole and the third through-hole to the two first vias, and respectively extends through the plurality of first vias to the fourth sub-layer, and continues in the first direction to the second side, so as to electrically connect the output capacitors of the first circuit board and the second circuit board through the two second vias; The first secondary-side trace of the two secondary-side traces extends from the second sub-layer board in a circumferential direction to the two first vias, and respectively extends through the two first vias to the fifth sub-layer board, and continues the first direction to the second side, so as to electrically connect the output capacitors of the first circuit board and the second circuit board through the two second vias respectively. wherein the second secondary-side trace of the two secondary-side traces extends from the first sub-layer in a second direction surrounding the first through-hole and the third through-hole to the two third vias, and respectively extends to the fourth sub-layer through the two third vias, and continues the second direction to extend to the second side, so as to electrically connect the output capacitors of the first circuit board and the second circuit board through the two fourth vias; and The second secondary-side trace of the two secondary-side traces extends from the second sub-layer board in a circumferential direction to the two third vias, and respectively extends to the fifth sub-layer board through the two third vias, and continues the second direction to the second side, so as to electrically connect the output capacitors of the first circuit board and the second circuit board through the two fourth vias respectively. The first direction and the second direction are opposite to each other along the first through hole, and the first direction and the second direction are opposite to each other along the third through hole.

9. The resonant converter of claim 8, wherein the first circuit board through-hole further comprises a second through-hole extending through the first circuit board, and the second circuit board through-hole further comprises a fourth through-hole extending through the second circuit board, and the core further comprises a second core leg extending through the second through-hole and the fourth through-hole; two first cast holes are respectively formed on a third side of the second through-hole and the fourth through-hole, and two second cast holes are respectively formed on a fourth side opposite the third side, and the two first cast holes and the two second cast holes are respectively used to electrically connect the first sub-layer board and the second sub-layer board; two third cast holes are respectively formed on the third side, and two fourth cast holes are respectively formed on the fourth side, and the two third cast holes and the two fourth cast holes are respectively used to electrically connect the first sub-layer board and the second sub-layer board; in, The first switch and the second switch of the first circuit board and the second circuit board are disposed on the fourth side; wherein a first secondary-side trace of the two secondary-side traces extends from the first sub-layer in the second direction surrounding the second through-hole and the fourth through-hole to the two first vias, and respectively extends through the two first vias to the second sub-layer, and continues in the second direction to the fourth side, so as to electrically connect the output capacitors of the first circuit board and the second circuit board through the two second vias; The second secondary-side trace of the two secondary-side traces extends from the first sub-layer board in the first direction surrounding the second through-hole and the fourth through-hole to the two third vias, and respectively extends to the second sub-layer board through the two third vias, and continues the first direction to extend to the fourth side, so as to electrically connect the output capacitors of the first circuit board and the second circuit board through the two fourth vias. 10 . The resonant converter according to claim 9 , wherein the first secondary-side traces in the first direction and the second direction of the first circuit board are integrally formed, or the second secondary-side traces in the first direction and the second direction are integrally formed. 11 . The resonant converter according to claim 9 , wherein the first secondary-side traces in the first direction and the second direction of the second circuit board are integrally formed, or the second secondary-side traces in the first direction and the second direction are integrally formed.

12. The resonant converter of claim 8, wherein the planar transformer further comprises: Two primary-side traces are formed on the first circuit board and a third sub-layer board of the second circuit board respectively; A second conductive column is disposed between the first circuit board and the second circuit board and electrically connected to the two primary-side traces to form a primary-side winding of the flat-plate transformer.

13. The resonant converter of claim 1 , further comprising: an inductor through-hole, comprising a first inductor through-hole and a second inductor through-hole, wherein the first inductor through-hole passes through the first circuit board, and the second inductor through-hole passes through the second circuit board; An inductor core includes two covers, each of the two covers includes a main body, and one of the two covers includes two side portions; Two inductor traces electrically connected to the plurality of traces and respectively surrounding the first inductor through-hole and the second inductor through-hole; and The two side portions protrude from the periphery of the body, and one of the two side portions passes through the first inductor through-hole and the second inductor through-hole.

14. The resonant converter of claim 1 , wherein the core further comprises: Two covers, one of which forms the first core column, and each of which includes a main body and a plurality of side portions; The side portions of the two covers are correspondingly protruded from the periphery of the main body, and the side portions are located at one of the outer sides of the first circuit board and the second circuit board to form an air gap. 15 . The resonant converter as claimed in claim 1 , wherein traces on different layers form an acute angle with the via as the center, and the acute angle is between 25 degrees and 35 degrees.

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