201233031 六、發明說明： 【發明所屬之技術領域】 [0001] 本發明涉及電源供應系統，特別涉及一種返驰式電源供 應系統。 【先前技術】 [0002] 返馳式電源供應系統中，一般採用一個變壓器、一組輸 出整流電路及迴授電路來控制輸出的電壓/電流。此變壓 器因兼具存儲與隔離功能，通常高度較高，導致其體積 很大，因而很難滿足電子產品對體積輕薄的需求。此外 ，因變壓器的有效導通週期小，在無載或輕載時，功率 損耗較大。 【發明内容】 [0003] 有鑑於此，需提供一種返驰式電源供應系統，在無載或 輕載時，功耗較小。 [0004] 一種返馳式電源供應系統，包括整流濾波電路、脈衝寬 度調變控制器、迴授電路、主轉換電路、從轉換電路及 從轉換控制電路。主轉換電路用於根據該脈衝寬度調變 控制器的控制，將該整流濾波電路輸出的訊號轉換為第 一直流電源訊號，以驅動負載。從轉換電路用於當該負 載為重載時，根據該脈衝寬度調變控制器的控制，將該 整流濾波電路輸出的訊號轉換為第二直流電源訊號，並 疊加至該第一直流電源訊號，以共同驅動該負載。從轉 換控制電路連接於該脈衝寬度調變控制器與該從轉換電 路之間，包括第一開關，該第一開關包括控制極、第一 電極及第二電極，該第一電極連接該脈衝寬度調變控制 100102318 表單編號A0101 第4頁/共27頁 1002004145-0 201233031201233031 VI. Description of the Invention: [Technical Field] [0001] The present invention relates to a power supply system, and more particularly to a flyback power supply system. [Prior Art] [0002] In a flyback power supply system, a transformer, a set of output rectifier circuits, and a feedback circuit are generally used to control the output voltage/current. Because of its combination of storage and isolation, this transformer is usually high in height, resulting in a large volume, making it difficult to meet the thin and light demand of electronic products. In addition, because the effective conduction period of the transformer is small, the power loss is large when there is no load or light load. SUMMARY OF THE INVENTION [0003] In view of the above, it is desirable to provide a flyback power supply system that consumes less power when there is no load or light load. [0004] A flyback power supply system includes a rectification filter circuit, a pulse width modulation controller, a feedback circuit, a main conversion circuit, a slave conversion circuit, and a slave conversion control circuit. The main conversion circuit is configured to convert the signal outputted by the rectifying and filtering circuit into a first DC power signal to drive the load according to the control of the pulse width modulation controller. The conversion circuit is configured to convert the signal output by the rectifying and filtering circuit into a second DC power signal and superimpose the signal to the first DC power signal according to the control of the pulse width modulation controller when the load is a heavy load. To drive the load together. The switching control circuit is connected between the pulse width modulation controller and the slave conversion circuit, and includes a first switch, the first switch includes a control electrode, a first electrode and a second electrode, wherein the first electrode is connected to the pulse width Modulation control 100102318 Form number A0101 Page 4 / Total 27 pages 1002004145-0 201233031
[0005] [0006] Ο [0007] 器，該第二電極連接該從轉換電路，該從轉換控制電路 用於偵測該負載是否為重載，若該負載為重載，則控制 該第一開關導通，以控制該脈衝寬度調變控制器的脈衝 寬度調變訊號進入該從轉換電路，使該從轉換電路將該 整流濾波電路輸出的訊號轉換為該第二直流電源訊號， 及若該負載為輕載或無載，則控制該第一開關截止，以 控制該脈衝寬度調變控制器的脈衝寬度調變訊號不進入 該從轉換電路，使該從轉換電路不進行轉換。 優選地，該主轉換電路包括第一變壓器及第二開關。第 一變壓器包括初級繞組與次級繞組。第二開關受控於該 脈衝寬度調變控制器。其中，該第一變壓器的初級繞組 、該第二開關與第一電阻依次串聯於該整流濾波電路的 輸出端與地之間。 優選地，該主轉換電路還包括第一二極體及第一電容。 第一二極體的陽極連接該第一變壓器的次級繞組的高壓 端，陰極輸出該第一直流電源訊號，用於整流。第一電 容一端連接該第一二極體的陰極，另一端接地，用於濾 波。 優選地，該從轉換電路包括第二變壓器及第三開關。第 二變壓器包括初級繞組與次級繞組。第三開關連接該從 轉換控制電路，用於當該從轉換控制電路控制該脈衝寬 度調變控制器的脈衝寬度調變訊號進入該從轉換電路時 ，接收並受控於該脈衝寬度調變訊號。其中，該第二變 壓器的初級繞組、該第三開關與第二電阻依次串聯於該 整流濾波電路的輸出端與地之間。 100102318 表單編號Α0101 第5頁/共27頁 1002004145-0 201233031 [0008] 優選地，該從轉換電路還包括第二二極體及第二電容。 第二二極體的陽極連接該第二變壓器的次級繞組的高壓 端，陰極輸出該第二直流電源訊號，用於整流。第二電 容一端連接該第二二極體的陰極，另一端接地，用於濾 波。 [0009] 優選地，該從轉換控制電路偵測該第一電阻及該第二電 阻的電壓，根據該偵測的第一電阻及第二電阻的電壓是 否超過最大允許負載時第一電阻與第二電阻的電壓的預 定比例，來確定該負載是否為重載。 [0010] 優選地，該從轉換控制電路偵測該迴授電路的迴授訊號 的電壓，根據該偵測的迴授訊號的電壓是否超過最大允 許負載時迴授訊號的電壓的預定比例，來確定該負載是 否為重載。 [0011] 優選地，該從轉換控制電路還包括第一比較器及第二比 較器。第一比較器包括正輸入端、負輸入端及輸出端， 該負輸入端經由第三電阻接收該偵測電壓並經由第三電 容接地，該正輸入端經由第四電阻接收第一參考電壓並 經由第三二極體及第五電阻連接該第一比較器的輸出端 ，該第三二極體的陽極連接該正輸入端，該第三二極體 的陰極連接該第五電阻，該第一比較器的輸出端連接該 第一開關的控制極。第二比較器包括正輸入端、負輸入 端及輸出端，該第二比較器的負輸入端接收第二參考電 壓，該第二比較器的正輸入端經由第六電阻接收該偵測 電壓並經由第四電容接地，該第二比較器的輸出端連接 該第一比較器的負輸入端。 100102318 表單編號A0101 第6頁/共27頁 1002004145-0 201233031 [0012] 優選地，該從轉換控制電路還包括第四二極體、第五二 極體及第六二極體。該第四二極體的陽極接收該偵測電 壓，該第四二極體的陰極連接該第三電阻，用於防止訊 號回流。該第五二極體的陽極接收該偵測電壓，該第四 二極體的陰極連接該第六電阻，用於防止訊號回流。該 第六二極體的陽極連接該第二比較器的輸出端，該第六 二極體的陰極連接該第一比較器的負輸入端，用於防止 訊號回流。 ^ [0013] 〇 優選地，該第一比較器的負輸入端經由該第三電阻連接 該第一電阻，來接收該偵測電壓，該第二比較器的正輸 入端經由該第六電阻連接該第二電阻，來接收該偵測電 壓。 [0014] 優選地，該脈衝寬度調變控制器用於根據該第一電阻的 電壓判斷該負載的狀況，並根據該迴授電路的迴授訊號 及該負載狀況相應調整該脈衝寬度調變訊號的占空比。 [0015] ❹ 優選地，該脈衝寬度調變控制器還用於根據該第二電阻 的電壓判斷該負載的狀況。 [0016] 優選地，該脈衝寬度調變控制器用於根據該迴授電路的 迴授訊號的電壓判斷該負載的狀況，並根據該負載的狀 況相應調整該脈衝寬度調變訊號的占空比。 [0017] 優選地，當該脈衝寬度調變控制器判斷該負載為重載時 ，調大該脈衝寬度調變訊號的占空比，及當判斷該負載 為輕載或無載時，調小該脈衝寬度調變訊號的占空比。 [0018] 優選地，該脈衝寬度調變控制器根據該偵測電壓是否超 100102318 表單編號A0101 第7頁/共27頁 1002004145-0 201233031 過最大允許負載時電壓的預定比例，來確定該負載是否 為重載。 [0019] 上述返驰式電源供應系統經由從轉換控制電路的控制， 使從轉換電路僅在負載為重載時工作，以與主轉換電路 共同驅動負載，提供足夠的驅動電源，而在輕載或無載 時，從轉換電路不工作，僅由主轉換電路驅動負載，因 而，返驰式電源供應系統的功率損耗達到最小，提升效 率。 【實施方式】 [0020] 圖1為本發明一實施方式中返馳式電源供應系統1 0的示意 圖。在本實施方式中，返驰式電源供應系統10用於將交 流電源訊號Vin轉換為直流電源訊號Vo，以驅動負載。其 中，交流電源訊號Vin為220V的交流市電。返驰式電源供 應系統10包括整流濾波電路100、脈衝寬度調變控制器 110、迴授電路120、主轉換電路130、從轉換電路140及 從轉換控制電路150。整流濾波電路100用於將交流電源 訊號Vin整流濾波為直流電源訊號，其包括全橋整流電路 及濾波電容。在本實施方式中，該直流電源訊號幅值為 200〜330V，例如為311V。迴授電路120用於根據返馳式 電源供應系統10輸出的直流電源訊號Vo，產生迴授訊號 ，並迴授至脈衝寬度調變控制器110。脈衝寬度調變控制 器110用於根據迴授訊號及負載狀況，產生相應的脈衝寬 度調變訊號，以控制主轉換電路130及從轉換電路140。 在本實施方式中，負載狀況包括負載為重載、負載為輕 載及負載為無載。在本實施方式中，當實際負載超過最 100102318 表單編號A0101 第8頁/共27頁 1002004145-0 201233031 [0021] [0022] Ο [0023] 〇 大允許負載的預定比例時，則認定負載狀況為重載，其 中，該預定比例可根據實際狀況設定及調節，例如，可 為 30%或40% ° 主轉換電路1 30用於根據脈衝寬度調變控制器11 0的控制 ，將整流濾波電路100輸出的直流電源訊號轉換為第一直 流電源訊號，以驅動負載。 從轉換電路140用於當該負載為重載時，根據脈衝寬度調 變控制器110的控制，將整流濾波電路100輸出的直流電 源訊號轉換為第二直流電源訊號，並疊加至第一直流電 源訊號，以共同驅動負載。 從轉換控制電路150連接於脈衝寬度調變控制器110與從 轉換電路140之間，用於偵測負載是否為重載。從轉換控 制電路150包括第一開關Q1，第一開關Q1包括控制極、第 一電極及第二電極。第一開關Q1的第一電極連接脈衝寬 度調變控制器110，第二電極連接從轉換電路140。若負 載為重載，從轉換控制電路150控制第一開關Q1導通，以 控制脈衝寬度調變控制器110的脈衝寬度調變訊號進入從 轉換電路140，使從轉換電路140將整流濾波電路100輸 出的直流電源訊號轉換為第二直流電源訊號。若負載為 輕載或無載，則從轉換控制電路150控制第一開關Q1截止 ，以控制脈衝寬度調變控制器110的脈衝寬度調變訊號不 進入從轉換電路140，使從轉換電路140不進行轉換。 如此，經由從轉換控制電路15 0的控制，從轉換電路14 0 僅在負載為重載時工作，以與主轉換電路130共同驅動負 100102318 表單編號Α0101 第9頁/共27頁 1002004145-0 [0024] 201233031 載，提供足夠的驅動電源。而在輕載或無載時，從轉換 電路140不工作，僅由主轉換電路130驅動負載，因而， 返驰式電源供應系統10的功率損耗達到最小，提升效率 〇 [0025] 圖2所示為本發明一實施方式中返驰式電源供應系統1 0的 具體電路圖。在本實施方式中，主轉換電路130包括第一 變壓器T1、第二開關Q2及第一電阻R1。第一變壓器T1包 括初級繞組與次級繞組，其中初級繞組的高壓端連接整 流濾波電路100。第二開關Q2包括控制極、第一電極及第 二電極，其中第二開關Q2的控制極連接脈衝寬度調變控 制器110，第一電極連接第一變壓器T1的初級繞組的低壓 端，第二電極經由第一電阻R1接地，即第一變壓器T1的 初級繞組、第二開關Q2及第一電阻R1依次串聯於整流濾 波電路100的輸出端與地之間。第二開關Q2受控於脈衝寬 度調變控制器110，即根據脈衝寬度調變訊號導通或裁止 ，從而使第一變壓器T1將整流濾波電路100輸出的直流電 源訊號轉換為第一方波訊號。 [0026] 在本實施方式中，主轉換電路130還包括第一二極體D1及 第一電容C1。第一二極體D1用於整流，其陽極連接第一 變壓器T1的次級繞組的高壓端，陰極輸出第一直流電源 訊號。第一電容C1用於濾波，其一端連接第一二極體D1 的陰極，另一端接地。 [0027] 從轉換電路140包括第二變壓器T2、第三開關Q3及第二電 阻R2。第二變壓器T2包括初級繞組與次級繞組，其中第 二變壓器T2的初級繞組的高壓端連接整流濾波電路1 00。 100102318 表單編號A0101 第10頁/共27頁 1002004145-0 201233031 ❹ [0028] Ο [0029] [0030] 100102318 第三開關Q3連接從轉換控制電路15〇，用於當從轉換控制 電路150控制脈衝寬度調變控制器11〇的脈衝寬度調變訊 號進入從轉換電路140時，接收脈衝寬度調變訊號，並根 據接收的脈衝寬度調變訊號導通或截止，從而使第二變 壓器Τ2將整流濾波電路1 〇〇輸出的直流電源訊號轉換為第 二方波訊號。第三開關Q3也包括控制極、第一電極及第 二電極，其中第二開關Q3的控制極連接從轉換控制電路 150的第一開關Q1的第二電極，第一電極連接第二變壓器 Τ 2的初級繞組的低壓端’第二電極經由第二電阻r 2接地 ：.'： ; V. 。即第二變壓器Τ2的初級繞組、第三開關q3與第二電阻 R 2依次串聯於整流濾波電路1 〇 〇的輪出端與地之間。 在本實施方式中’從轉換電路140還包括第二二極體])2及 第二電容C2 ^第二二極體1)2用於整流，其陽極連接第二 變壓器Τ2的次級繞組的高壓端，陰極輸處第二直流電源 訊號。第二電容C2用於濾波’其广端連接第二二極體D2 的陰極，另一端接地。' 在本實施方式中，第一開關Q1為PNP型電晶體，其控制極 為基極，第一電極為射極，第二電極為集極。第二開關 Q2與第三開關Q3均為金屬氧化物半導體場效應電晶體， 第二開關Q2與第三開關Q3的控制極均為閘極，第一電極 均為汲極，第二電極均為源極。 在本實施方式中，從轉換控制電路150連接第二開關Q2的 第二電極及第三開關Q3的第二電極，用於偵測第一電阻 R1及第二電阻R2的電壓，偵測負載是否為重載。在本實 施方式中，當實際負載超過最大允許負载的預定比例時 第11頁/共27頁 表單編號A0101 1002004145-0 201233031 ’則遇疋負載狀況為重载’其中，該預定比例可根據實 際狀況设定及調節’例如，可為3〇%或4〇%。因而，從轉 換控制電路150偵測第—電阻R1及第二電阻以的電壓判 斷第-ΊΡΜΙ及第二電阻R2的實際電壓是否超過最大允 許負載時電壓的預定比例，來判斷負載是否為重載。若 實際電壓超過最大允許負載時電壓的預定比例，判斷負 載為重載’則從轉換控制電路150相應控制第-開關…導 通，使脈衝寬度調變控制器11G的脈衝寬度調變訊號進入 第二開關Q3的控制極。若實时壓未超過最大允許負載 時電壓的預定比例’判斷負載為輕栽或無載，則從轉換 控制電路150相應控制帛—開關以截纟，.使該脈衝寬度調 變控制器11G的脈衝寬度調變訊號不進人第三關⑽的控 制極。 [0031] [0032] 在本發明的另一實施方式中，從轉換控制電路15〇連接迴 授電路120，偵測迴授電路12〇的迴授訊號的電壓，根據 實際的迴授訊號的電壓是否超過最大允許負載時迴授訊 號的電壓的預定比例，來確定負載是否為重載。 在本實施方式中，從轉換控制電路150包括第一比較器 1501及第二比較器1502，第一比較器1501及第二比較器 1 502均包括正輸入端 '負輸入端及輸出端。第一比較器 1501的負輸入端經由第三電阻R3接收偵測電壓，即連接 第一電阻R1或連接迴授電路120，並經由第三電容C3接地 。第一比較器1501的正輸入經由第四電阻R4接收第一參 考電壓Vccl ’並經由第三二極體D3及第五電阻R5連接第 一比較器1501的輸出端。第三二極體D3的陽極連接第一 100102318 表箪編號A0101 第12頁/共27頁 1002004145-0 201233031 [0033] [0034] θ [0035] Ο 比較器1501的正輸入端，陰極連接第五電阻R5。 較器1 501的輸出端連接第一開關Q1的控制極。 第二比較器1 502的負輸入端接收第二參考電壓，正輸入 端經由第六電阻R6接收該偵測電壓，即連接第二電阻R2 及迴授電路120，並經由第四電容C4接地。第二比較器 1 502的輸出端連接第一比較器1501的負輸入端。 在本實施方式中，因第一電阻R1與第二電阻R2上的電壓 為脈衝訊號，第三電阻R3與第三電容C3用於將第一電阻 R1上脈衝形式的電壓轉換成穩定的平均電壓，以與第一 參考電壓Vccl比較，第六電阻R6與第四電容C4用於將第 二電阻R2上脈衝形式的電壓轉換成穩定的平均電壓，以 與第二參考電壓Vcc2比較。 在本實施方式中，脈衝寬度調變控制器110偵測第一電阻 R1的電壓，判斷第一電阻R1的實際電壓是否超過最大允 許負載時電壓的預定比例，來確定負載狀況，並根據負 載狀況及迴授電路120的迴授訊號相應調整脈衝寬度調變 訊號的占空比。若脈衝寬度調變控制器110判斷負載為重 載時，調大脈衝寬度調變訊號的占空比，從而延長第二 開關Q2及第三開關Q3的導通時間，使得主轉換電路130及 從轉換電路140提供足夠的直流電源訊號Vo至負載。若判 斷負載為輕載或無載時，脈衝寬度調變控制器110調小脈 衝寬度調變訊號的占空比，從而縮短第二開關Q2的導通 時間，使得主轉換電路130提供適量的直流電源訊號Vo至 負載。 第一比 100102318 表單編號A0101 第13頁/共27頁 1002004145-0 201233031 [0036] 在本發明的另一實施方式中，脈衝寬度調變控制器11 0偵 測迴授電路120的迴授訊號的電壓，根據實際的迴授訊號 的電壓是否超過最大允許負載時迴授訊號的電壓的預定 比例，來確定負載是否為重載。 [0037] 在本實施方式中，假設最大允許負載時第一電阻R1上的 平均電壓為5V，判斷上述由輕載轉為重載的預定比例為 40%，則設定第一參考電壓Vccl為2V而由重載轉為輕載[0006] [0006] The second electrode is connected to the slave switching circuit, and the slave switching control circuit is configured to detect whether the load is a heavy load, and if the load is a heavy load, control the first The switch is turned on to control the pulse width modulation signal of the pulse width modulation controller to enter the slave conversion circuit, so that the slave conversion circuit converts the signal output by the rectifier filter circuit into the second DC power signal, and if the load For light load or no load, the first switch is turned off to control the pulse width modulation signal of the pulse width modulation controller not to enter the slave conversion circuit, so that the slave conversion circuit does not perform conversion. Preferably, the main conversion circuit includes a first transformer and a second switch. The first transformer includes a primary winding and a secondary winding. The second switch is controlled by the pulse width modulation controller. The primary winding of the first transformer, the second switch and the first resistor are sequentially connected in series between the output end of the rectifying and filtering circuit and the ground. Preferably, the main conversion circuit further includes a first diode and a first capacitor. The anode of the first diode is connected to the high voltage end of the secondary winding of the first transformer, and the cathode outputs the first DC power signal for rectification. One end of the first capacitor is connected to the cathode of the first diode and the other end is grounded for filtering. Preferably, the slave switching circuit includes a second transformer and a third switch. The second transformer includes a primary winding and a secondary winding. a third switch is connected to the slave switching control circuit, configured to receive and control the pulse width modulation signal when the slave pulse width modulation signal of the pulse width modulation controller is controlled by the slave switching control circuit . The primary winding of the second transformer, the third switch and the second resistor are sequentially connected in series between the output end of the rectifying and filtering circuit and the ground. 100102318 Form No. Α0101 Page 5 of 27 1002004145-0 201233031 [0008] Preferably, the slave conversion circuit further includes a second diode and a second capacitor. The anode of the second diode is connected to the high voltage end of the secondary winding of the second transformer, and the cathode outputs the second DC power signal for rectification. One end of the second capacitor is connected to the cathode of the second diode, and the other end is grounded for filtering. [0009] Preferably, the slave switching control circuit detects the voltages of the first resistor and the second resistor, and according to whether the detected voltage of the first resistor and the second resistor exceeds a maximum allowable load, the first resistor and the first resistor A predetermined ratio of the voltages of the two resistors to determine if the load is a heavy load. [0010] Preferably, the slave switching control circuit detects the voltage of the feedback signal of the feedback circuit, and according to whether the detected feedback signal voltage exceeds a predetermined ratio of the voltage of the feedback signal at the maximum allowable load. Determine if the load is overloaded. [0011] Preferably, the slave switching control circuit further includes a first comparator and a second comparator. The first comparator includes a positive input terminal, a negative input terminal, and an output terminal. The negative input terminal receives the detection voltage via a third resistor and is grounded via a third capacitor, and the positive input terminal receives the first reference voltage via the fourth resistor and Connecting the output end of the first comparator via a third diode and a fifth resistor, the anode of the third diode is connected to the positive input end, and the cathode of the third diode is connected to the fifth resistor, the first The output of a comparator is coupled to the gate of the first switch. The second comparator includes a positive input terminal, a negative input terminal and an output terminal. The negative input terminal of the second comparator receives the second reference voltage, and the positive input terminal of the second comparator receives the detected voltage via the sixth resistor and The fourth comparator is grounded, and the output of the second comparator is coupled to the negative input of the first comparator. 100102318 Form No. A0101 Page 6 of 27 1002004145-0 201233031 [0012] Preferably, the slave switching control circuit further includes a fourth diode, a fifth diode, and a sixth diode. The anode of the fourth diode receives the detection voltage, and the cathode of the fourth diode is connected to the third resistor for preventing signal backflow. The anode of the fifth diode receives the detection voltage, and the cathode of the fourth diode is connected to the sixth resistor for preventing signal backflow. The anode of the sixth diode is connected to the output of the second comparator, and the cathode of the sixth diode is connected to the negative input of the first comparator for preventing signal backflow. [0013] Preferably, the negative input terminal of the first comparator is connected to the first resistor via the third resistor to receive the detection voltage, and the positive input terminal of the second comparator is connected via the sixth resistor The second resistor receives the detected voltage. [0014] Preferably, the pulse width modulation controller is configured to determine a condition of the load according to the voltage of the first resistor, and adjust the pulse width modulation signal according to the feedback signal of the feedback circuit and the load condition. Duty cycle. [0015] Preferably, the pulse width modulation controller is further configured to determine a condition of the load according to a voltage of the second resistor. [0016] Preferably, the pulse width modulation controller is configured to determine a condition of the load according to a voltage of the feedback signal of the feedback circuit, and adjust a duty ratio of the pulse width modulation signal according to a condition of the load. [0017] Preferably, when the pulse width modulation controller determines that the load is a heavy load, the duty ratio of the pulse width modulation signal is increased, and when the load is determined to be light or no load, the frequency is reduced. The duty cycle of the pulse width modulation signal. [0018] Preferably, the pulse width modulation controller determines whether the load is based on whether the detected voltage exceeds 100102318 Form No. A0101, page 7 / page 27, 1002004145-0 201233031, a predetermined ratio of the maximum allowable load voltage. For heavy loads. [0019] The flyback power supply system is controlled by the slave switching control circuit so that the slave converter circuit operates only when the load is heavy, to drive the load together with the main converter circuit, and provides sufficient driving power, while at a light load When the load is not loaded, the slave switching circuit does not work, and only the main converter circuit drives the load. Therefore, the power loss of the flyback power supply system is minimized and the efficiency is improved. [Embodiment] FIG. 1 is a schematic diagram of a flyback power supply system 10 according to an embodiment of the present invention. In the present embodiment, the flyback power supply system 10 is configured to convert the AC power signal Vin into a DC power signal Vo to drive the load. Among them, the AC power signal Vin is 220V AC mains. The flyback power supply system 10 includes a rectification filter circuit 100, a pulse width modulation controller 110, a feedback circuit 120, a main conversion circuit 130, a slave conversion circuit 140, and a slave conversion control circuit 150. The rectifying and filtering circuit 100 is configured to rectify and filter the AC power signal Vin into a DC power signal, which includes a full bridge rectifier circuit and a filter capacitor. In this embodiment, the DC power signal has an amplitude of 200 to 330 V, for example, 311 V. The feedback circuit 120 is configured to generate a feedback signal according to the DC power signal Vo output from the flyback power supply system 10, and send it back to the pulse width modulation controller 110. The pulse width modulation controller 110 is configured to generate a corresponding pulse width modulation signal according to the feedback signal and the load condition to control the main conversion circuit 130 and the slave conversion circuit 140. In the present embodiment, the load conditions include a load being a heavy load, a load being a light load, and a load being a no load. In the present embodiment, when the actual load exceeds the most 100102318 Form No. A0101 Page 8 / Total 27 Page 1002004145-0 201233031 [0021] [0022] [0023] When the predetermined ratio of the allowable load is increased, the load condition is determined as Heavy load, wherein the predetermined ratio can be set and adjusted according to actual conditions, for example, 30% or 40%. The main conversion circuit 1 30 is used to control the rectification filter circuit 100 according to the control of the pulse width modulation controller 110. The output DC power signal is converted to a first DC power signal to drive the load. The conversion circuit 140 is configured to convert the DC power signal outputted by the rectification and filtering circuit 100 into a second DC power signal according to the control of the pulse width modulation controller 110 when the load is a heavy load, and superimpose it on the first DC Power signals to drive the load together. The slave switching control circuit 150 is connected between the pulse width modulation controller 110 and the slave switching circuit 140 for detecting whether the load is a heavy load. The slave switching control circuit 150 includes a first switch Q1 including a control electrode, a first electrode, and a second electrode. The first electrode of the first switch Q1 is coupled to the pulse width modulation controller 110, and the second electrode is coupled to the slave conversion circuit 140. If the load is a heavy load, the first switch Q1 is controlled to be turned on by the switching control circuit 150 to control the pulse width modulation signal of the pulse width modulation controller 110 to enter the slave conversion circuit 140, so that the slave rectifier circuit 140 outputs the rectifier filter circuit 100. The DC power signal is converted into a second DC power signal. If the load is light load or no load, the first switch Q1 is controlled to be turned off by the switching control circuit 150 to control the pulse width modulation signal of the pulse width modulation controller 110 not to enter the slave conversion circuit 140, so that the slave conversion circuit 140 does not Make the conversion. Thus, via the control from the switching control circuit 150, the slave switching circuit 14 0 operates only when the load is overloaded, and drives the negative 100102318 together with the main converter circuit 130. Form number Α 0101 Page 9 / Total 27 pages 1002004145-0 [ 0024] 201233031, providing enough drive power. In the case of light load or no load, the slave switching circuit 140 does not operate, and only the main converter circuit 130 drives the load. Therefore, the power loss of the flyback power supply system 10 is minimized, and the efficiency is improved. [0025] A specific circuit diagram of the flyback power supply system 10 in an embodiment of the present invention. In the present embodiment, the main conversion circuit 130 includes a first transformer T1, a second switch Q2, and a first resistor R1. The first transformer T1 includes a primary winding and a secondary winding, wherein the high voltage end of the primary winding is coupled to the rectifier filter circuit 100. The second switch Q2 includes a control electrode, a first electrode and a second electrode, wherein the control electrode of the second switch Q2 is connected to the pulse width modulation controller 110, the first electrode is connected to the low voltage end of the primary winding of the first transformer T1, and the second The electrode is grounded via the first resistor R1, that is, the primary winding of the first transformer T1, the second switch Q2, and the first resistor R1 are sequentially connected in series between the output end of the rectifying and filtering circuit 100 and the ground. The second switch Q2 is controlled by the pulse width modulation controller 110, that is, the pulse width modulation signal is turned on or off according to the pulse width, so that the first transformer T1 converts the DC power signal outputted by the rectifier filter circuit 100 into the first square wave signal. . In the present embodiment, the main conversion circuit 130 further includes a first diode D1 and a first capacitor C1. The first diode D1 is used for rectification, the anode is connected to the high voltage end of the secondary winding of the first transformer T1, and the cathode outputs the first DC power signal. The first capacitor C1 is used for filtering, and one end thereof is connected to the cathode of the first diode D1, and the other end is grounded. [0027] The slave conversion circuit 140 includes a second transformer T2, a third switch Q3, and a second resistor R2. The second transformer T2 includes a primary winding and a secondary winding, wherein the high voltage terminal of the primary winding of the second transformer T2 is connected to the rectifying filter circuit 100. 100102318 Form No. A0101 Page 10 of 27 1002004145-0 201233031 ❹ [0028] 100102318 The third switch Q3 is connected from the switching control circuit 15A for controlling the pulse width from the switching control circuit 150 When the pulse width modulation signal of the modulation controller 11〇 enters the slave conversion circuit 140, the pulse width modulation signal is received, and the modulation signal is turned on or off according to the received pulse width, so that the second transformer Τ2 will rectify the filter circuit 1 The output DC power signal is converted to a second square wave signal. The third switch Q3 also includes a control electrode, a first electrode and a second electrode, wherein the control electrode of the second switch Q3 is connected to the second electrode of the first switch Q1 of the switching control circuit 150, and the first electrode is connected to the second transformer Τ 2 The low voltage end of the primary winding 'the second electrode is grounded via the second resistor r 2 :.': ; V. That is, the primary winding of the second transformer Τ2, the third switch q3 and the second resistor R 2 are sequentially connected in series between the rounding end of the rectifying and filtering circuit 1 〇 与 and the ground. In the present embodiment, 'the slave switching circuit 140 further includes a second diode>) 2 and the second capacitor C2 ^the second diode 1) 2 is used for rectification, and the anode thereof is connected to the secondary winding of the second transformer Τ2 At the high voltage end, the cathode is at the second DC power signal. The second capacitor C2 is used to filter the cathode of the second diode D2 whose wide end is connected, and the other end is grounded. In the present embodiment, the first switch Q1 is a PNP type transistor whose control electrode is a base, the first electrode is an emitter, and the second electrode is a collector. The second switch Q2 and the third switch Q3 are both metal oxide semiconductor field effect transistors, and the control electrodes of the second switch Q2 and the third switch Q3 are both gates, the first electrodes are all drain electrodes, and the second electrodes are all Source. In the present embodiment, the second electrode of the second switch Q2 and the second electrode of the third switch Q3 are connected from the switching control circuit 150 for detecting the voltages of the first resistor R1 and the second resistor R2 to detect whether the load is For heavy loads. In the present embodiment, when the actual load exceeds a predetermined ratio of the maximum allowable load, the 11th page/total 27 page form number A0101 1002004145-0 201233031 'The load condition is overloaded', wherein the predetermined ratio may be based on the actual situation The setting and adjustment 'for example, may be 3〇% or 4〇%. Therefore, the switching control circuit 150 detects whether the voltage of the first resistor R1 and the second resistor determines whether the actual voltage of the first and second resistors R2 exceeds a predetermined ratio of the maximum allowable load voltage to determine whether the load is overloaded. . If the actual voltage exceeds a predetermined ratio of the voltage at the maximum allowable load, and the load is judged to be overloaded, then the first switch is turned on from the switching control circuit 150, so that the pulse width modulation signal of the pulse width modulation controller 11G enters the second The control pole of switch Q3. If the real-time pressure does not exceed the predetermined ratio of the voltage at the maximum allowable load, and the load is judged to be light or no load, the switch control circuit 150 controls the switch to switch, so that the pulse width modulation controller 11G The pulse width modulation signal does not enter the control pole of the third level (10). [0032] In another embodiment of the present invention, the feedback control circuit 15 is connected to the feedback circuit 120 to detect the voltage of the feedback signal of the feedback circuit 12, according to the voltage of the actual feedback signal. Whether the load exceeds a predetermined ratio of the voltage of the feedback signal at the maximum allowable load to determine whether the load is a heavy load. In the present embodiment, the slave switching control circuit 150 includes a first comparator 1501 and a second comparator 1502. The first comparator 1501 and the second comparator 1 502 each include a positive input terminal 'negative input terminal and an output terminal. The negative input terminal of the first comparator 1501 receives the detection voltage via the third resistor R3, that is, connects the first resistor R1 or the connection feedback circuit 120, and is grounded via the third capacitor C3. The positive input of the first comparator 1501 receives the first reference voltage Vccl' via the fourth resistor R4 and is coupled to the output of the first comparator 1501 via the third diode D3 and the fifth resistor R5. Anode connection of the third diode D3 First 100102318 Table No. A0101 Page 12 / Total 27 page 1002004145-0 201233031 [0034] θ [0035] 正 Positive input of the comparator 1501, cathode connected fifth Resistor R5. The output of the comparator 1 501 is connected to the control electrode of the first switch Q1. The negative input terminal of the second comparator 1 502 receives the second reference voltage, and the positive input terminal receives the detected voltage via the sixth resistor R6, that is, connects the second resistor R2 and the feedback circuit 120, and is grounded via the fourth capacitor C4. The output of the second comparator 1 502 is coupled to the negative input of the first comparator 1501. In this embodiment, since the voltages on the first resistor R1 and the second resistor R2 are pulse signals, the third resistor R3 and the third capacitor C3 are used to convert the voltage in the form of a pulse on the first resistor R1 into a stable average voltage. In comparison with the first reference voltage Vccl, the sixth resistor R6 and the fourth capacitor C4 are used to convert the voltage in the form of a pulse on the second resistor R2 into a stable average voltage to be compared with the second reference voltage Vcc2. In this embodiment, the pulse width modulation controller 110 detects the voltage of the first resistor R1, determines whether the actual voltage of the first resistor R1 exceeds a predetermined ratio of the maximum allowable load, and determines the load condition, and according to the load condition. And the feedback signal of the feedback circuit 120 adjusts the duty ratio of the pulse width modulation signal accordingly. If the pulse width modulation controller 110 determines that the load is a heavy load, the duty ratio of the pulse width modulation signal is increased, thereby extending the conduction time of the second switch Q2 and the third switch Q3, so that the main conversion circuit 130 and the slave conversion Circuit 140 provides sufficient DC power signal Vo to the load. If it is determined that the load is light load or no load, the pulse width modulation controller 110 adjusts the duty ratio of the pulse width modulation signal, thereby shortening the conduction time of the second switch Q2, so that the main conversion circuit 130 provides an appropriate amount of DC power. Signal Vo to load. First ratio 100102318 Form No. A0101 Page 13 / Total 27 pages 1002004145-0 201233031 [0036] In another embodiment of the present invention, the pulse width modulation controller 110 detects the feedback signal of the feedback circuit 120. The voltage determines whether the load is heavy or not based on whether the voltage of the actual feedback signal exceeds a predetermined ratio of the voltage of the feedback signal at the maximum allowable load. [0037] In the present embodiment, assuming that the average voltage on the first resistor R1 is 5V when the maximum allowable load is satisfied, and determining that the predetermined ratio from light load to heavy load is 40%, setting the first reference voltage Vccl to 2V From heavy load to light load
的預定比例略小，約為35%，則設定第二參考電壓為0. 8V 〇 [0038] 當負載為輕載時，從轉換電路140不工作，因而第二電阻 R2上的電壓為0，即第二比較器1502的正輸入端的電壓為 0，小於第二比較器1 502的負輸入端的電壓，第二比較器 1502輸出低電平訊號。因為此時為輕載，第一電阻R1上 的電壓經第三電阻R3及第三電容C4轉換後的平均電壓小 於重載時平均電壓與預定比例的乘積，即小於2V，第一 比較器1501的負輸入端電壓小於正輸入端電壓，第一比 較器1501輸出高電平訊號。因而，第一開關Q1截止，此 時，脈衝寬度調變訊號無法進入第三開關Q3的控制極， 從轉換電路140不進行工作。 [0039] 當負載由輕載轉為重載時，因從轉換電路140未進行工作 ，第二比較器1 502仍輸出低電平訊號。而脈衝寬度調變 訊號的占空比變大，使得第一電阻R1的電壓變大，當第 一電阻R1的電壓經第三電阻R3及第三電容C3轉換後的平 均電壓大於重載時的平均電壓與預定比例的乘積，即大 於2V，第一比較器1501的負輸入端電壓大於正輸入端電 100102318 表單編號A0101 第14頁/共27頁 1002004145-0 201233031The predetermined ratio is slightly smaller, about 35%, and the second reference voltage is set to 0. 8V 〇 [0038] When the load is light load, the slave conversion circuit 140 does not work, and thus the voltage on the second resistor R2 is 0. That is, the voltage of the positive input terminal of the second comparator 1502 is 0, which is smaller than the voltage of the negative input terminal of the second comparator 1502, and the second comparator 1502 outputs a low level signal. Because it is light load at this time, the average voltage of the voltage on the first resistor R1 after being converted by the third resistor R3 and the third capacitor C4 is smaller than the product of the average voltage at the heavy load and the predetermined ratio, that is, less than 2V, the first comparator 1501 The negative input terminal voltage is less than the positive input terminal voltage, and the first comparator 1501 outputs a high level signal. Therefore, the first switch Q1 is turned off, and at this time, the pulse width modulation signal cannot enter the gate of the third switch Q3, and the slave switching circuit 140 does not operate. [0039] When the load is changed from light load to heavy load, the second comparator 1 502 still outputs a low level signal because the slave switching circuit 140 is not operating. The duty ratio of the pulse width modulation signal becomes larger, so that the voltage of the first resistor R1 becomes larger, and the average voltage of the voltage of the first resistor R1 after being converted by the third resistor R3 and the third capacitor C3 is greater than that of the heavy load. The product of the average voltage and the predetermined ratio, that is, greater than 2V, the voltage of the negative input terminal of the first comparator 1501 is greater than the power of the positive input terminal 100102318 Form No. A0101 Page 14 / Total 27 pages 1002004145-0 201233031
[0040]G[0040] G
[0041] Ο [0042] 100102318 壓，第—比較器15〇l輸出低電平訊號。第一開關Q1導通 ，此時，脈衝寬度調變訊號進入第三開關Q3的控制極， 從轉換電路140開始工作。此時，第三二極體D3導通，用 於籍位’將第一參考電壓以01的2¥電壓均分在第四電阻 R4與第五電阻R5上，從而拉低第一比較器15〇1的輸出端 即第一開關Q1的控制極的電壓準位，使第一開關Q1保持 導通狀態，確保從轉換電路14〇持續工作。 當負載為重載時，第二比較器15〇2的正輸入端電壓大於 負輸入端電壓，輸出高電平訊號。第一比較器15〇1的負 輸入端電壓大於正輪入端電壓，輸出低電平訊號，第一 開關Q1保持導通，從轉換電路14〇持衊工作。 當負載由重载變為輕載，脈衝寬度調變訊號的占空比變 小，第一電阻R1與第二電阻R2的電壓均變小。當第二電 阻R2的電壓經第六電阻R6與第四電容(^4轉換後的平均電 壓小於第二比較器15〇2負輪入端電壓且第一電阻R1的電 壓經第三電阻R3與第三電容C3轉換後的平均電壓小於第 一比較器1501的正輸入端電壓時，第二比較器15〇2輸出 低電平訊號，第-比較器15()1輸出高電平訊號。因而， 第一開關Q1截止，從轉換電路14〇停止工作。 圖3所示為本發明另一實施方式中返馳式電源供應系統20 的具體電路圖。在本實施方式中，返馳式《供應系統 20與圖2中返驰式電源供應系統1〇的區別在於返驰式電源 供應系統2G的從轉換控制電路15qa還包括第四二極频 、第五二極舰及第六二極義，其餘部分完全相同， 因而此處不再贅述。第四二極體_極接㈣料壓， 表單蹁號A0101 第15頁/共27頁 1002004145-0 201233031 :二接第—電阻I陰極連接第三電阻R3。第五二 極連接接收偵測電壓，例如，連接第二電阻R2，陰 第六二極體⑽陽極連接第二比較器 的輸出端，陰極連接第—比較器的負輪入端。第四 一極體D4、第五-社 弟五-極體D5及第六二極體D6均用於防止訊 號回流。 [0043] [0044] [0045] [0046] 圖4所不為本發明另—實施方式中返驰式電源供應系統30 的”體電路圖。在本實施方式中，返馳式電源供應系統 3〇與圖2與3中返驰式電源供應系統U)、20的區別在於返 馳式電源供應系統⑽的脈衝寬度調彻制^1iq還連接第 二開關Q3的第二電極，其餘部分完全相，同，因而此處不 再贅述。脈衝寬度調變控制器110還用於根據第二電阻R2 的電壓判斷負載的狀況。 本發明的返馳式電源供應系統10、20、30經由從轉換控 制電路150、150A的控制，使從轉換電路14〇僅在負載為 重載時工作，以與主轉換電路丄形)共同驅動負载提供足 夠的驅動電源，而在輕載或無载時，從轉換電路14〇不工 作’僅由主轉換電路13〇驅動負載，因而，返馳式電源供 應系統10、20、30的功率損耗達到最小，提升效率。 此外，返馳式電源供應系統10、20、30應用兩個變壓器 ΤΙ ' T2，取代了傳統的一個變壓器，從而大大降低了返 馳式電源供應系統10、20、30的高度，使得電子產品輕 薄化。 综上所述，本發明符合發明專利要件，爰依法提出專利 100102318 表單編號A0101 第16頁/共27頁 1002004145-0 201233031 申請。惟，以上所述者僅為本發明之較佳實施例，舉凡 熟悉本案技藝之人士，在爰依本案發明精神所作之等效 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】 [0047] 圖1為本發明一實施方式中返馳式電源供應系統的示意圖 [0048] 圖2為本發明一實施方式中返馳式電源供應系統的具體電 路圖； 〇 [〇〇49] 圖3為本發明另一實施方式中返馳式電源供應系統的具體 電路圖；及 [0050] 圖4為本發明又一實施方式中返驰式電源供應系統的具體 電路圖。 【主要元件符號說明】 [0051] 返馳式電源供應系統：10、20、30 [0052] 整流濾波電路：100 \ . ·ν '… [0053] 脈衝寬度調變控制器：110 [0054] 迴授電路：120 [0055] 主轉換電路：130 [0056] 從轉換電路：140 [0057] 第一及第二變壓器 :τι、Τ2 [0058] 第二及第三開關： Q2、Q3 [0059] 第一及第二電阻： Rl、R2 表單編號A0101 第17頁/共27頁[0041] 102 [0042] 100102318 Press, the first comparator 15〇l outputs a low level signal. The first switch Q1 is turned on. At this time, the pulse width modulation signal enters the control electrode of the third switch Q3 and starts to operate from the conversion circuit 140. At this time, the third diode D3 is turned on, and the second reference voltage is divided by the 2¥ voltage of the first reference voltage to the fourth resistor R4 and the fifth resistor R5, thereby pulling down the first comparator 15〇. The output terminal of 1 is the voltage level of the gate of the first switch Q1, so that the first switch Q1 is kept in an on state, ensuring continuous operation from the converter circuit 14A. When the load is heavy, the positive input voltage of the second comparator 15〇2 is greater than the negative input voltage, and a high level signal is output. The voltage of the negative input terminal of the first comparator 15〇1 is greater than the voltage of the positive wheel input terminal, and the low level signal is output, and the first switch Q1 remains turned on, and the switching circuit 14 is operated. When the load is changed from a heavy load to a light load, the duty ratio of the pulse width modulation signal becomes small, and the voltages of the first resistor R1 and the second resistor R2 become smaller. When the voltage of the second resistor R2 passes through the sixth resistor R6 and the fourth capacitor (the average voltage after the conversion is smaller than the negative voltage of the second comparator 15〇2 and the voltage of the first resistor R1 passes through the third resistor R3 and When the average voltage after the third capacitor C3 is converted is smaller than the voltage of the positive input terminal of the first comparator 1501, the second comparator 15〇2 outputs a low level signal, and the first comparator 15()1 outputs a high level signal. The first switch Q1 is turned off, and the operation is stopped from the switching circuit 14A. Fig. 3 is a specific circuit diagram of the flyback power supply system 20 according to another embodiment of the present invention. In the present embodiment, the flyback type "supply system" 20 is different from the flyback power supply system 1 in FIG. 2 in that the slave switching control circuit 15qa of the flyback power supply system 2G further includes a fourth two-pole frequency, a fifth two-pole ship, and a sixth two-pole meaning, and the rest. The parts are identical and therefore will not be described here. The fourth diode _ pole connection (four) material pressure, form nickname A0101 page 15 / total 27 page 1002004145-0 201233031: two connection - resistance I cathode connection third resistor R3. The fifth two-pole connection receives the detection voltage, for example, Connected to the second resistor R2, the cathode of the cathode 6th diode (10) is connected to the output end of the second comparator, and the cathode is connected to the negative wheel input end of the first comparator. The fourth pole body D4, the fifth-social five-pole Both the body D5 and the sixth diode D6 are used to prevent signal reflow. [0044] [0046] FIG. 4 is not the body of the flyback power supply system 30 in another embodiment of the present invention. In the present embodiment, the flyback power supply system 3 is different from the flyback power supply systems U) and 20 of FIGS. 2 and 3 in the pulse width modulation system of the flyback power supply system (10). The second electrode of the second switch Q3 is also connected, and the rest is completely phased and the same, and thus will not be described herein. The pulse width modulation controller 110 is further configured to determine the condition of the load according to the voltage of the second resistor R2. The flyback power supply system 10, 20, 30 is controlled by the slave switching control circuit 150, 150A so that the slave switching circuit 14 工作 operates only when the load is heavy, to provide a sufficient load to drive the load together with the main converter circuit. Drive power, while at light load or no load, from the conversion circuit 14〇 does not work 'The load is driven only by the main conversion circuit 13〇, and thus, the power loss of the flyback power supply systems 10, 20, 30 is minimized, and the efficiency is improved. Further, the flyback power supply system 10, 20, 30 The application of two transformers T 'T2 replaces the traditional one transformer, thereby greatly reducing the height of the flyback power supply system 10, 20, 30, making the electronic product light and thin. In summary, the invention complies with the invention patent requirements , 爰Proposed patent 100102318 Form No. A0101 Page 16 / Total 27 Page 1002004145-0 201233031 Application. The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be included in the following claims. BRIEF DESCRIPTION OF THE DRAWINGS [0047] FIG. 1 is a schematic diagram of a flyback power supply system according to an embodiment of the present invention; [0048] FIG. 2 is a specific circuit diagram of a flyback power supply system according to an embodiment of the present invention; FIG. 3 is a specific circuit diagram of a flyback power supply system according to another embodiment of the present invention; and FIG. 4 is a specific circuit diagram of a flyback power supply system according to still another embodiment of the present invention. [Main component symbol description] [0051] Flyback power supply system: 10, 20, 30 [0052] Rectifier filter circuit: 100 \ . · ν '... [0053] Pulse width modulation controller: 110 [0054] Grant circuit: 120 [0055] Main conversion circuit: 130 [0056] Slave conversion circuit: 140 [0057] First and second transformers: τι, Τ 2 [0058] Second and third switches: Q2, Q3 [0059] One and second resistance: Rl, R2 Form No. A0101 Page 17 of 27
100102318 1002004145-0 201233031 [0060] 第一及第二二極體：D1、D2 [0061] 第一及第二電容：Cl、C2100102318 1002004145-0 201233031 [0060] First and second diodes: D1, D2 [0061] First and second capacitors: Cl, C2
[0062] 從轉換控制電路：1 50、1 50A[0062] Slave switching control circuit: 1 50, 1 50A
[0063] 第一開關：Q1 [0064] 第一比較器：1501 [0065] 第二比較器·· 1502 [0066] 第三至第六電阻：R3、R4、R5、R6 [0067] 第三及第四電容：C3、C4 [0068] 第三至第六二極體：D3、D4、D5、D6 [0069] 第一及第二參考電壓：Vccl、Vcc2 [0070] 交流電源訊號：Vi η [0071] 直流電源訊號：Vo 1002004145-0 100102318 表單編號A0101 第18頁/共27頁[0063] First switch: Q1 [0064] First comparator: 1501 [0065] Second comparator 1502 [0066] Third to sixth resistors: R3, R4, R5, R6 [0067] Fourth capacitor: C3, C4 [0068] Third to sixth diodes: D3, D4, D5, D6 [0069] First and second reference voltages: Vccl, Vcc2 [0070] AC power signal: Vi η [ 0071] DC power signal: Vo 1002004145-0 100102318 Form number A0101 Page 18 of 27