M396538 五、新型說明： 【新型所屬之技術領域】 [0001] 本新型涉及電源供應系統，尤其涉及一種多組輸出的電 源供應系統。 【先前技術】 [0002] LLC諧振架構為電源供應系統常採用的架構，其一般採用 整合電感和變壓器在同一顆磁性元件上。當多組輸出時 ，僅用一顆變壓器進行隔離，然後在此變壓器上加多組 線圈或在輸出端上加上直流/直流轉換器，來達成多組輸 出。然而，變壓器做隔離再加多組線圈，體積較大，很 難達成扁平化，因而，無法有效縮小產品的尺寸。 【新型内容】 [0003] 有鑑於此，需提供一種電源供應系統，具有較小的體積 〇 [0004] 一種電源供應系統，用於驅動複數負載，該電源供應系 統包括電源轉換電路、脈衝寬度調變控制器、第一隔離 變壓器、至少兩個第二變壓器及至少兩個整流電路。電 源轉換電路用於將外部電源訊號轉換為第一交流電源訊 號。脈衝寬度調變控制器用於控制該電源轉換電路。第 一隔離變壓器用於將該第一交流電源訊號轉換為第二交 流電源訊號，該第一隔離變壓器包括初級繞組與次級繞 組，該初級繞組與該電源轉換電路相連。至少兩個第二 變壓器分別用於升/降壓該第二交流電源訊號，該等第二 變壓器均包括初級繞組與次級繞組，該等第二變壓器的 表單编號A0101 第3頁/共16頁 M396538 初級繞組並聯連接該第一隔離變壓器的次級繞組，該等 . 第二變壓器的次級繞組的中心抽頭分別接地。每一整流 電路對應連接一個第二變壓器的次級繞組的兩端，用於 整流該升/降壓後的第二交流電源訊號，並分別輸出直流 電源訊號至該等負載。 [0005] 優選地，該電源供應系統還包括LLC諧振電路，連接於該 電源轉換電路與該第一隔離變壓器之間，該LLC諧振電路 包括第一電容、第一電感及第二電感，該第一電容連接 於該電源轉換電路與該第一電感的一端之間，該第二電 感連接於該第一電感的另一端與地之間並與該第一隔離 變壓器的初級繞組並聯。 [0006] 優選地，每一整流電路包括兩個二極體，該等二極體的 陽極分別連接相應第二變壓器的次級繞組的兩端，陰極 相連並輸出該直流電源訊號。 [0007] 優選地，該電源供應系統還包括至少兩個第二濾波電容 ，分別對應連接每一整流電路與地之間。 [0008] 一種電源供應系統，用於驅動複數負載，該電源供應系 統包括電源轉換電路、脈衝寬度調變控制器、第一隔離 變壓器、第二變壓器、第一整流電路及第二整流電路。 電源轉換電路用於將外部電源訊號轉換為第一交流電源 訊號。脈衝寬度調變控制器用於控制該電源轉換電路。 第一隔離變壓器用於將該第一交流電源訊號轉換為第二 交流電源訊號，該第一隔離變壓器包括初級繞組與次級 繞組，該初級繞組與該電源轉換電路相連。第二變壓器 表單編號A0101 第4頁/共16頁 M396538 用於升/降壓該第二交流電源訊號，該第二變壓器包括初 級繞組與次級繞組，該第二變壓器的初級繞組連接該第 一隔離變壓器的次級繞組，該第二變壓器的次級繞組的 中心抽頭接地。第一整流電路連接該第二變壓器的次級 繞組的兩端，用於整流該升/降壓後的第二交流電源訊號 ，並輸出第一直流電源訊號至該等負載。第二整流電路 與該第二變壓器並聯連接該第一隔離變壓器的次級繞組 ，用於整流該第二交流電源訊號，並輸出第二直流電源 訊號至該等負載。 [0009] 優選地，該電源供應系統還包括LLC諧振電路，連接於該 電源轉換電路與該第一隔離變壓器之間，該LLC諧振電路 包括第一電容、第一電感及第二電感，該第一電容連接 於該電源轉換電路與該第一電感的一端之間，該第二電 感連接於該第一電感的另一端與地之間並與該第一隔離 變壓器的初級繞組並聯。M396538 V. New description: [New technical field] [0001] The present invention relates to a power supply system, and more particularly to a power supply system with multiple sets of outputs. [Prior Art] [0002] The LLC resonant architecture is a commonly used architecture for power supply systems, which typically employs an integrated inductor and a transformer on the same magnetic component. When multiple sets of outputs are used, only one transformer is used for isolation, and then multiple sets of coils are added to the transformer or a DC/DC converter is added to the output to achieve multiple sets of outputs. However, the transformer is isolated and a plurality of coils are added, which is bulky and difficult to achieve flatness, and thus cannot effectively reduce the size of the product. [New content] [0003] In view of this, it is necessary to provide a power supply system having a small volume [0004] A power supply system for driving a plurality of loads, the power supply system including a power conversion circuit, pulse width modulation a variable controller, a first isolation transformer, at least two second transformers, and at least two rectifier circuits. The power conversion circuit is used to convert the external power signal into the first AC power signal. A pulse width modulation controller is used to control the power conversion circuit. The first isolation transformer is configured to convert the first alternating current power signal into a second alternating current power signal. The first isolation transformer includes a primary winding and a secondary winding, the primary winding being coupled to the power conversion circuit. At least two second transformers are respectively used for raising/lowering the second alternating current power signal, and the second transformers each include a primary winding and a secondary winding, and the second transformer forms No. A0101 Page 3 of 16 Page M396538 The primary winding is connected in parallel to the secondary winding of the first isolation transformer, and the center taps of the secondary windings of the second transformer are grounded separately. Each rectifying circuit is connected to two ends of a secondary winding of a second transformer for rectifying the second AC power signal after the stepping up/down, and outputting a DC power signal to the loads respectively. [0005] Preferably, the power supply system further includes an LLC resonant circuit connected between the power conversion circuit and the first isolation transformer, the LLC resonant circuit including a first capacitor, a first inductor, and a second inductor, the first A capacitor is coupled between the power conversion circuit and one end of the first inductor, and the second inductor is coupled between the other end of the first inductor and ground and in parallel with the primary winding of the first isolation transformer. [0006] Preferably, each rectifier circuit includes two diodes, and the anodes of the diodes are respectively connected to two ends of the secondary windings of the respective second transformers, and the cathodes are connected and output the DC power signals. [0007] Preferably, the power supply system further includes at least two second filter capacitors respectively connected between each rectifier circuit and the ground. [0008] A power supply system for driving a plurality of loads, the power supply system including a power conversion circuit, a pulse width modulation controller, a first isolation transformer, a second transformer, a first rectifier circuit, and a second rectifier circuit. The power conversion circuit is used to convert the external power signal into the first AC power signal. A pulse width modulation controller is used to control the power conversion circuit. The first isolation transformer is configured to convert the first alternating current power signal into a second alternating current power signal, the first isolation transformer comprising a primary winding and a secondary winding, the primary winding being coupled to the power conversion circuit. Second Transformer Form No. A0101 Page 4 of 16 M396538 is used to raise/decel the second AC power signal, the second transformer includes a primary winding and a secondary winding, and the primary winding of the second transformer is connected to the first The secondary winding of the isolation transformer, the center tap of the secondary winding of the second transformer is grounded. The first rectifier circuit is connected to the two ends of the secondary winding of the second transformer for rectifying the second AC power signal after the step-up/down, and outputting the first DC power signal to the loads. The second rectifier circuit is connected in parallel with the second transformer to the secondary winding of the first isolation transformer for rectifying the second AC power signal and outputting a second DC power signal to the loads. [0009] Preferably, the power supply system further includes an LLC resonant circuit connected between the power conversion circuit and the first isolation transformer, the LLC resonant circuit including a first capacitor, a first inductor, and a second inductor, the first A capacitor is coupled between the power conversion circuit and one end of the first inductor, and the second inductor is coupled between the other end of the first inductor and ground and in parallel with the primary winding of the first isolation transformer.
[0010] 優選地，該第一整流電路包括兩個二極體，該等二極體 的陽極分別連接該第二變壓器的次級繞組的兩端，陰極 相連並輸出該第一直流電源訊號。 [0011] 優選地，該第二整流電路包括兩個二極體，該等二極體 的陽極分別連接該第一隔離變壓器的次級繞組的兩端， 陰極相連並輸出該第二直流電源訊號。 [0012] 優選地，該電源供應系統還包括至少兩個第二濾波電容 ，分別對應連接該第一整流電路與地之間與該第二整流 電路與地之間。 表單編號A0101 第5頁/共16頁 M396538 [0013] 本新型的電源供應系統以第一隔離變壓器做初次級安全 隔離，第二變壓器不需進行隔離，使第一隔離變壓器與 第二變壓器效能提高且容易扁平化，使得電源供應系統 體積較小，從而利於產品的小型化。 【實施方式】 [0014] 圖1為本新型提出的電源供應系統1 0第一實施方式的示意 圖。如圖1所示，電源供應系統10用於將外部電源訊號 Vin轉換為直流電源訊號，以驅動複數負載L21、L22… 及L2n (η為大於等於2的整數）。其中，負載L21、L22 …及L2n包括發光二極體、電子線路等，其由不同的直流 電源訊號驅動。在本實施方式中，外部電源訊號Vi η為直 流訊號。電源供應系統10包括電源轉換電路100、脈衝寬 度調變控制器110、第一隔離變壓器Τ1、至少兩個第二變 壓器Τ21、Τ22…及Τ2η (η為大於等於2的整數）及至少 兩個整流電路121、122…及12η (η為大於等於2的整數 )。電源轉換電路100用於將外部電源訊號Vin轉換為第 一交流電源訊號。在本實施方式中，電源轉換電路10 0包 括半橋電路。脈衝寬度調變控制器110用於控制電源轉換 電路100。 [0015] 第一隔離變壓器T1用於將第一交流電源訊號轉換為第二 交流電源訊號並進行初次級安全隔離，其包括初級繞組 與次級繞組，初級繞組與電源轉換電路100相連。在本實 施方式中，第二交流電源訊號為方波訊號。 [0016] 第二變壓器T21、T22…及T2n分別用於升/降壓第二交流 電源訊號，其均包括初級繞組與次級繞組。第二變壓器 表單編號Α0101 第6頁/共16頁 M396538 T21、T22…及Τ2η的初級繞組並聯連接第一隔離變壓器 Τ1的次級繞組，次級繞組的中心抽頭分別接地。[0010] Preferably, the first rectifier circuit comprises two diodes, the anodes of the diodes are respectively connected to two ends of the secondary winding of the second transformer, and the cathodes are connected and output the first DC power signal. . [0011] Preferably, the second rectifier circuit comprises two diodes, the anodes of the diodes are respectively connected to two ends of the secondary winding of the first isolation transformer, and the cathodes are connected and output the second DC power signal. . [0012] Preferably, the power supply system further includes at least two second filter capacitors respectively connected between the first rectifier circuit and the ground and the second rectifier circuit and the ground. Form No. A0101 Page 5 of 16 M396538 [0013] The new power supply system uses the first isolation transformer for primary and secondary safety isolation, and the second transformer does not need to be isolated to improve the efficiency of the first isolation transformer and the second transformer. And it is easy to flatten, making the power supply system small in size, which is conducive to miniaturization of the product. [Embodiment] FIG. 1 is a schematic view showing a first embodiment of a power supply system 10 proposed in the present invention. As shown in FIG. 1, the power supply system 10 is configured to convert an external power signal Vin into a DC power signal to drive the complex loads L21, L22, ..., and L2n (n is an integer greater than or equal to 2). The loads L21, L22, ..., and L2n include light-emitting diodes, electronic circuits, and the like, which are driven by different DC power signals. In this embodiment, the external power signal Vi η is a DC signal. The power supply system 10 includes a power conversion circuit 100, a pulse width modulation controller 110, a first isolation transformer Τ1, at least two second transformers Τ21, Τ22... and Τ2η (η is an integer greater than or equal to 2) and at least two rectifications Circuits 121, 122, ... and 12n (n is an integer greater than or equal to 2). The power conversion circuit 100 is configured to convert the external power signal Vin into a first AC power signal. In the present embodiment, the power conversion circuit 10 includes a half bridge circuit. The pulse width modulation controller 110 is used to control the power conversion circuit 100. [0015] The first isolation transformer T1 is configured to convert the first alternating current power signal into a second alternating current power signal and perform primary and secondary safety isolation, including a primary winding and a secondary winding, and the primary winding is connected to the power conversion circuit 100. In this embodiment, the second AC power signal is a square wave signal. [0016] The second transformers T21, T22, ..., and T2n are respectively used to boost/depress the second alternating current power signals, each of which includes a primary winding and a secondary winding. Second transformer Form No. Α0101 Page 6 of 16 M396538 The primary windings of T21, T22... and Τ2η are connected in parallel to the secondary winding of the first isolation transformer Τ1, and the center taps of the secondary winding are grounded separately.
[0017] 每一整流電路121、122…及12η對應連接一個第二變壓 器Τ21、Τ22…及Τ2η的次級繞組的兩端，用於整流升/降 壓後的第二交流電源訊號，並分別輸出直流電源訊號至 負載L21、L22…及L2n。在本實施方式中，整流電路121 連接於第二變壓器T21的次級繞組與負載L21之間，整流 電路122連接於第二變壓器T22與負載L22之間，整流電 路12η連接於第二變壓器T2n與負載L2n之間。每一整流 電路121、122…及12η包括兩個二極體D1與D2。整流電 路121的二極體D1與D2的陽極分別連接第二變壓器Τ21的 次級繞組的兩端，陰極相連並輸出直流電源訊號至負載 L21。整流電路122的二極體D1與D2的陽極分別連接第二 變壓器Τ22的次級繞組的兩端，陰極相連並輸出直流電源 訊號至負載L22。整流電路12η的二極體D1與D2的陽極分 別連接第二變壓器Τ2η的次級繞組的兩端，陰極相連並輸 出直流電源訊號至負載L2n。在本實施方式中，整流電路 121、122…及12η輸出的直流電源訊號不同。 [0018] 在本實施方式中，電源供應系統10還包括LLC諧振電路 130，連接於電源轉換電路100與第一隔離變壓器Τ1之間 ，其包括第一電容C1、第一電感L1及第二電感L2。第一 電容C1連接於電源轉換電路100與第一電感L1的一端之間 ，第二電感L2連接於第一電感L1的另一端與地之間並與 第一隔離變壓器Τ1的初級繞組並聯。在本新型的另一實 施方式中，第二電感L2為第一隔離變壓器Τ1的漏感。 表單編號Α0101 第7頁/共16頁 M396538 [0019] 在本實施方式中，電源供應系統10還包括至少兩個第二 濾波電容C2，分別對應連接每一整流電路121、122…及 12η與地之間，特別的，連接每一整流電路121、122··· 及12η的輸出端與地之間。 [0020] 圖2所示為本新型提出的電源供應系統20第二實施方式的 示意圖。如圖2所示，電源供應系統20用於將外部電源訊 號Vin轉換為直流電源訊號，以驅動複數負載L30、L31 及L3m (3為大於等於1的整數）。其中，負載L30、L31 及L3m包括發光二極體、電子線路等，其由不同的直流電 源訊號驅動。在本實施方式中，外部電源訊號Vin為直流 訊號。電源供應系統20包括電源轉換電路100、脈衝寬度 調變控制器110、第一隔離變壓器T1、第二變壓器T31及 T3ra(m為大於等於1的整數）、第一整流電路221及22m (m為大於等於1的整數）及第二整流電路220。電源轉換 電路100、脈衝寬度調變控制器110、第一隔離變壓器T1 、及第二變壓器T31及T3m同圖1中的相同，因而此處不再 贅述。 [0021] 第一整流電路221及22m連接第二變壓器Τ31及T3m的次級 繞組的兩端，用於整流該升/降壓後的第二交流電源訊號 ，並輸出第一直流電源訊號至負載L31及L3m。 [0022] 第二整流電路220與第二變壓器T31及T3m並聯連接第一 隔離變壓器T1的次級繞組，用於整流第二交流電源訊號 ，並輸出第二直流電源訊號至負載L30。 [0023] 在本實施方式中，第一整流電路221及22m與第二整流電 表單編號A0101 第8頁/共16頁 M396538 路220分別包括兩個二極體D1與!)2。第一整流電路221的 二極體D1與D2的陽極分別連接第二變壓器T31的次級繞組 的兩端，陰極相連並輸出第—直流電源訊號至負載Mi。 第一整流電路22m的二極體D1與D2的陽極分別連接第二變 壓器T3m的次級繞組的兩端，陰極相連並輸出第一直流電 源訊號至負載L3m。第二整流電路220的二極體^與!)〗的 陽極分別連接第一隔離變壓ST1的次級繞組的兩端，陰 極相連並輪出第二直流電源訊號至負載L3〇。在本實施方 式中’第一整流電路221、22m及第二整流電路220輸出 的直流電源訊號不同。 [0024] 在本實施方式中，電源供應系統20還包括LLC諳振電路 130 ’連接於電源轉換電路1〇〇與第一隔離變壓器T1之間 ’其包括第一電容C1、第一電感L1及第二電感L2。第一 電容C1連接於電源轉換電路1〇〇與第一電感L1的一端之間 ’第二電感L2連接於第一電感L1的另一端與地之間並與 第一隔離變壓器T1的初級繞組並聯。在本新型的另一實 施方式中，第二電感L2為第一隔離變壓器T1的漏感。 [0025] 在本實施方式中，電源供應系統1〇還包括至少兩個第二 濾波電容C2，分別對應連接第一整流電路221、22m與地 之間及第二整流電路220與地之間，特別的，第二遽波電 容C2連接第一整流電路221、22m的輸出端與地之間及第 二整流電路220的輸出端與地之間。 [0026] 本新型的電源供應系統10、20以第一隔離變壓器T1做初 次級安全隔離，第二變壓器不需進行隔離，使第一隔離 變壓器T1與第二變壓器效能提高且容易扁平化，使得電 表單編號A0101 第9頁/共16頁 M396538 源供應系統10、20體積較小，從而利於產品的小型化。 此外，第二變壓器不需安全隔離，成本降低。另外，利 用第二變壓器調整圈比，達成所需的輸出電壓。 [0027] 綜上所述，本新型符合新型專利要件，爰依法提出專利 申請。惟，以上所述者僅為本新型之較佳實施例，舉凡 熟悉本案技藝之人士，在爰依本案.新型精神所作之等效 修飾或變化，皆應包含於以下之申請專利範圍内。 【圖式簡單說明】 [0028] 圖1為本新型第一實施方式中電源供應系統的示意圖；及 [0029] 圖2為本新型第二實施方式中電源供應系統的示意圖。 【主要元件符號說明】 [0030] 電源供應系統：10、20 [0031] 電源轉換電路：100 [0032] 脈衝寬度調變控制器：110 [0033] 第一隔離變壓器：T1 [0034] 第二變壓器：T2卜 T22、T2n、T31、T3m [0035] 整流電路：121、122、12η [0036] 第一整流電路：221、22m [0037] 第二整流電路：220 [0038] 二極體：Dl、D2 [0039] LLC諧振電路：130 表單編號A0101 第10頁/共16頁 M396538 [0040] 電容：Cl、C2 [0041] 電感：LI、L2 [0042] 外部電源訊號：Vin [0043] 負載：L21、L22、L2n、L31、L3m、L30 表單编號A0101 第11頁/共16頁[0017] Each of the rectifying circuits 121, 122, ..., and 12n is connected to two ends of a secondary winding of the second transformers Τ21, Τ22, ..., and Τ2n for rectifying the second AC power signal after the step-up/down steps, and respectively Output DC power signals to loads L21, L22... and L2n. In the present embodiment, the rectifier circuit 121 is connected between the secondary winding of the second transformer T21 and the load L21. The rectifier circuit 122 is connected between the second transformer T22 and the load L22, and the rectifier circuit 12n is connected to the second transformer T2n. Load between L2n. Each of the rectifying circuits 121, 122, ... and 12n includes two diodes D1 and D2. The anodes of the diodes D1 and D2 of the rectifier circuit 121 are respectively connected to the two ends of the secondary winding of the second transformer Τ21, and the cathode is connected and outputs a DC power signal to the load L21. The anodes of the diodes D1 and D2 of the rectifier circuit 122 are respectively connected to the two ends of the secondary winding of the second transformer Τ22, and the cathode is connected and outputs a DC power signal to the load L22. The anodes of the diodes D1 and D2 of the rectifier circuit 12n are respectively connected to both ends of the secondary winding of the second transformer Τ2n, and the cathode is connected and outputs a DC power signal to the load L2n. In the present embodiment, the DC power signals output from the rectifier circuits 121, 122, ..., and 12n are different. [0018] In the present embodiment, the power supply system 10 further includes an LLC resonant circuit 130 connected between the power conversion circuit 100 and the first isolation transformer T1, and includes a first capacitor C1, a first inductor L1, and a second inductor. L2. The first capacitor C1 is connected between the power conversion circuit 100 and one end of the first inductor L1, and the second inductor L2 is connected between the other end of the first inductor L1 and the ground and is connected in parallel with the primary winding of the first isolation transformer Τ1. In another embodiment of the present invention, the second inductance L2 is the leakage inductance of the first isolation transformer Τ1. Form No. 1010101 Page 7 of 16 M396538 [0019] In the present embodiment, the power supply system 10 further includes at least two second filter capacitors C2, which are respectively connected to each of the rectifier circuits 121, 122, ..., and 12n and ground. In particular, the output of each of the rectifier circuits 121, 122, . . . and 12n is connected to ground. 2 is a schematic diagram showing a second embodiment of the proposed power supply system 20 of the present invention. As shown in FIG. 2, the power supply system 20 is configured to convert the external power signal Vin into a DC power signal to drive the complex loads L30, L31, and L3m (3 is an integer greater than or equal to 1). Among them, the loads L30, L31 and L3m include a light-emitting diode, an electronic circuit, etc., which are driven by different DC power signals. In this embodiment, the external power signal Vin is a DC signal. The power supply system 20 includes a power conversion circuit 100, a pulse width modulation controller 110, a first isolation transformer T1, second transformers T31 and T3ra (m is an integer greater than or equal to 1), first rectifier circuits 221 and 22m (m is An integer greater than or equal to 1) and the second rectifier circuit 220. The power conversion circuit 100, the pulse width modulation controller 110, the first isolation transformer T1, and the second transformers T31 and T3m are the same as those in Fig. 1, and thus will not be described herein. [0021] The first rectifier circuits 221 and 22m are connected to the two ends of the second windings of the second transformers 31 and T3m for rectifying the second AC power signal after the step-up/down, and outputting the first DC power signal to Load L31 and L3m. [0022] The second rectifier circuit 220 is connected in parallel with the second transformers T31 and T3m to connect the secondary winding of the first isolation transformer T1 for rectifying the second AC power signal and outputting the second DC power signal to the load L30. In the present embodiment, the first rectifier circuits 221 and 22m and the second rectifier circuit number A0101 page 8/16 pages M396538 road 220 respectively include two diodes D1 and !)2. The anodes of the diodes D1 and D2 of the first rectifier circuit 221 are respectively connected to both ends of the secondary winding of the second transformer T31, and the cathode is connected and outputs a first DC power signal to the load Mi. The anodes of the diodes D1 and D2 of the first rectifier circuit 22m are respectively connected to both ends of the secondary winding of the second transformer T3m, and the cathode is connected and outputs a first DC power signal to the load L3m. The anodes of the second rectifier circuit 220 are connected to the two ends of the secondary winding of the first isolation transformer ST1, and the cathodes are connected and the second DC power signal is turned to the load L3. In the present embodiment, the DC power signals output by the first rectifier circuits 221 and 22m and the second rectifier circuit 220 are different. [0024] In the present embodiment, the power supply system 20 further includes an LLC resonant circuit 130' connected between the power conversion circuit 1A and the first isolation transformer T1, which includes a first capacitor C1, a first inductor L1, and The second inductance L2. The first capacitor C1 is connected between the power conversion circuit 1〇〇 and one end of the first inductor L1. The second inductor L2 is connected between the other end of the first inductor L1 and the ground and is connected in parallel with the primary winding of the first isolation transformer T1. . In another embodiment of the present invention, the second inductance L2 is the leakage inductance of the first isolation transformer T1. [0025] In the present embodiment, the power supply system 1A further includes at least two second filter capacitors C2 respectively connected between the first rectifier circuits 221, 22m and the ground and between the second rectifier circuit 220 and the ground. In particular, the second chopper capacitor C2 is connected between the output terminals of the first rectifier circuits 221, 22m and the ground and between the output terminals of the second rectifier circuit 220 and the ground. [0026] The power supply system 10, 20 of the present invention uses the first isolation transformer T1 as the primary and secondary safety isolation, and the second transformer does not need to be isolated, so that the performance of the first isolation transformer T1 and the second transformer is improved and is easy to flatten, so that Electric Form No. A0101 Page 9 of 16 M396538 The source supply system 10, 20 is small in size, which facilitates miniaturization of the product. In addition, the second transformer does not require safe isolation and the cost is reduced. In addition, the second transformer is used to adjust the ring ratio to achieve the desired output voltage. [0027] In summary, the present invention complies with the new patent requirements and submits a patent application according to law. However, the above-mentioned ones are only preferred embodiments of the present invention, and equivalent modifications or variations made by those skilled in the art in the present invention should be included in the following claims. BRIEF DESCRIPTION OF THE DRAWINGS [0028] FIG. 1 is a schematic diagram of a power supply system in a first embodiment of the present invention; and [0029] FIG. 2 is a schematic diagram of a power supply system in a second embodiment of the present invention. [Main component symbol description] [0030] Power supply system: 10, 20 [0031] Power conversion circuit: 100 [0032] Pulse width modulation controller: 110 [0033] First isolation transformer: T1 [0034] Second transformer : T2 T T22, T2n, T31, T3m [0035] Rectifier circuit: 121, 122, 12η [0036] First rectifier circuit: 221, 22m [0037] Second rectifier circuit: 220 [0038] Diode: Dl, D2 [0039] LLC Resonant Circuit: 130 Form No. A0101 Page 10 of 16 M396538 [0040] Capacitance: Cl, C2 [0041] Inductance: LI, L2 [0042] External Power Signal: Vin [0043] Load: L21 , L22, L2n, L31, L3m, L30 Form No. A0101 Page 11 of 16