200826462 .九、發明說明： 【發明所屬之技術領域】 本發明係關於一種電源電路。 【先前技術】 請參閱圖1，其係一種先前技術電源電路的電路結構 示意圖。該電源電路10包括一第一整流濾波電路11、一 保護電路13、一隔離高頻變壓器14、一第二整流濾波電路 15、一電晶體17、一反饋電路18及一脈寬調變控制器19。 其中，該第一整流濾波電路11包括二輸入端111、112、 一全橋整流電路113、一濾波電容114及一輸出端115，該 隔離高頻變壓器14包括一初級繞組141及一次級繞組 142,該第二整流濾波電路15包括二輸入端151、152及一 輸出端150,該脈寬調變控制器19包括一控制端191及一 電壓採樣端192。 該全橋整流電路113的二輸入端即該第一整流濾波電 路的二輸入端111、112,該全橋整流電路113的正輸出端 即該第一整流濾波電路的輸出端115,該全橋整流電路113 的負輸出端接地，該濾波電容114並聯在該全橋整流電路 113的正輸出端及負輸出端之間。該保護電路13與該隔離 高頻變壓器14的初級繞組141並聯。該隔離高頻變壓器 14的初級繞組141 一端與該第一整流濾波電路11的輸出 端115電連接，其另一端與該電晶體17的源極電連接。該 8 200826462 .隔離高頻變壓器14的次級繞組142與該第二整流濾波電路 15的二輸入端151、152電連接。該電晶體17的閘極與該 m 脈寬調變控制器19的控制端電連接，該電晶體17的汲極 藉由該反饋電路18與該脈寬調變控制器19的電壓採樣端 192電連接，該電晶體17的汲極同時藉由一限流電阻170 接地。 外界交流電壓輸入至該第一整流濾波電路11的二輸 入端111、112，藉由該第一整流濾波電路11整流、濾波 後輸出為直流電壓。當該電晶體17導通時，該濾波電容 114、該隔離高頻變壓器14的初級繞組141、該電晶體17 及該限流電阻170構成一迴路，此時，該濾波電容114等 效為"^直流電源’該初級繞組141等效為一電感’由公式· y = 表示濾波電容114的電壓，L表示初級繞組141 at 的電感，I表示流經該初級繞組141的電流）可知初級繞組 141中的電流線性增加，最後達到最大值。該反饋電路18 將該限流電阻170的電壓反饋至該脈寬調變控制器19的電 、 壓採樣端192,該脈寬調變控制器19將該反饋電壓與其參 考電壓進行比較，當反饋電壓高於其參考電壓時，該脈寬 調變控制器19的控制端191輸出低電平以控制該電晶體 17停止工作。 當該電晶體17截止時，該初級繞組141儲存的電能傳 輸至該次級繞組142，經該第二整流濾波電路15整流、濾 波後輸出穩定的直流電壓。該初級繞組141的勵磁電流藉 由該保護電路13消耗掉。 9 200826462 然，當輸入端111、112所連接的交流電源不同時，直 1出端150的過流點變化較大。例如，當交流電源為丽 在輸出端150測得過流點為2.61A，當交流電源為顺 時，在輸出端15G測得過流點為3.觀。當輸人端山、⑴ 所連接的交流電源的電壓很高時，電路中的電流也相岸較 大，若輸入側或輸出侧發生故障時，該電源電& ι〇就可能 【發明内容】 有鑑於此，提供一種使輸出端的過流點穩定的電源 路實為必需。 ' 一種電源電路，其包括一第一整流濾波電路、一隔離 高頻變壓器、一第二整流濾波電路、一電晶體、一反饋電 路一脈覓调變控制器及一補償電路。其中，該第一整流 濾波電路包括二輸入端及一輸出端，該隔離高頻變壓器包 ^括一初級繞組、一次級繞組及一辅助繞組，該第二整流濾 波電路包括二輸入端及一輸出端，該脈寬調變控制器包括 一控制端及一電壓採樣端。該隔離高頻變壓器的初級繞組 一端與該第一整流濾波電路的輸出端電連接，其另一端與 該電晶體的源極電連接；該隔離高頻變壓器的次級繞組與 該第二整流濾波電路的二輸入端電連接；該隔離高頻變壓 器的辅助繞組一端藉由該補償電路與該脈寬調變控制器的 電壓採樣端電連接，其另一端接地。該電晶體的閘極與該 脈寬調變控制器的控制端電連接；該電晶體的汲極藉由該 200826462 .反饋電路與該脈寬調變控制器的電壓採樣端電連接，該電 晶體的汲極同時接地。 與先前技術相比，本發明電源電路增加一補償電路以 對輸入側的電壓進行反饋，當輸入端所連接的交流電源變 化時，該補償電路將輔助繞組之感應電壓反饋至該脈寬調 變控制器的電壓採樣端，該反饋電壓與該反饋電路的反饋 電壓相疊加，該脈寬調變控制器將該總反饋電壓與其參考 電壓進行比較並發出相應的控制訊號以控制該電晶體，從 而使該電源電路輸出端的過流點穩定。 【實施方式】 請參閱圖2 ^其係本發明電源電路的電路結構不意 圖。該電源電路20包括一第一整流濾波電路21、一保護 電路23、一隔離高頻變壓器24、一第二整流濾波電路25、 一電晶體27、一反饋電路28、一脈寬調變控制器29及一 補償電路31，其中，該第一整流濾波電路21包括二輸入 端211、212、一全橋整流電路213、一濾波電容214及一 輸出端215。該隔離高頻變壓器24包括一初級繞組241、 一次級繞組242及一輔助繞組30。該第二整流濾波電路25 包括二輸入端251、252及一輸出端250。該脈寬調變控制 器29包括一控制端291及一電壓採樣端292。該補償電路 31包括一輸入端310、一輸出端315、一二極體313、一第 一電阻311及一第二電阻312。 該全橋整流電路213的二輸入端作為該第一整流濾波 11 200826462 /電路21的二輸入端211、212，該全橋整流電路213的正 ^ 輸出端作為該第一整流濾波電路21的輸出端215,該全橋 整流電路21的負輸出端接地，該濾波電容214並聯在該全 橋整流電路213的正輸出端及負輸出端之間。該保護電路 23與該隔離高頻變壓器24的初級繞組241並聯。該隔離 高頻變壓器24的初級繞組241 —端與該第一整流濾波電路 21的輸出端215電連接，其另一端與該電晶體27的源極 電連接。該隔離高頻變壓器24的次級繞組242與該第二整 流濾波電路25的二輸入端251、252電連接。該電晶體27 的閘極與該脈寬調變控制器29的控制端291電連接，該電 晶體27的汲極藉由該反饋電路28與該脈寬調變控制器29 的電壓採樣端292電連接，該電晶體27的汲極同時藉由一 限流電阻270接地。該隔離高頻變壓器24的輔助繞組30 一端與該補償電路31的輸入端310電連接，其另一端接 地。該二極體313及該第一電阻311串接在該補償電路31 的輸入端310與輸出端315之間，且該二極體313的負極 與該第一電阻311連接，該補償電路31的輸出端315與該 脈寬調變控制器29的電壓採樣端292電連接，其同時藉由 該第二電阻312接地。 外界交流電壓輸入至該第一整流濾波電路21的二輸 入端211、212，藉由該第一整流濾波電路21整流、濾波 後輸出為直流電壓。當該電晶體27導通時，該濾波電容 214、該隔離高頻變壓器24的初級繞組241、該電晶體27 及該限流電阻270構成一迴路，此時，該濾波電容214等 12 200826462 效為一直流電源，該初級繞組241等效為一電感，由公式： v = z!(V表示濾波電容214的電壓，L表示初級繞組241 的電感’ I表不流經該初級繞組241的電流）可知初級繞組 241中的電流線性增加，最後達到最大值。該反饋電路28 將該限流電阻270的電壓反饋至該脈寬調變控制器29的電 壓採樣端292。 該輔助繞組30、該二極體313、該第一電阻311及該 第二電阻312也構成一迴路，此時，該輔助繞組30等效為 一電源，由公式：s = m与（ε表示輔助繞組30的感應電動 勢，Μ表示初級繞組241與輔助繞組30的互感係數，I表 示初級繞組241中的電流）可知初級繞組241中的電流線性 變化時，該輔助繞組30的感應電動勢保持不變，該第二電 阻312的電壓反饋至該脈寬調變控制器29的電壓採樣端 292，該反饋電壓與反饋電路28的反饋電壓相疊加，該脈 寬調變控制器29將該總反饋電壓與其參考電壓進行比 較，當反饋電壓高於其參考電壓時，該脈寬調變控制器29 的控制端291輸出低電平以控制該電晶體27停止工作。 當該電晶體27截止時，該初級繞組241儲存的電能傳 輸至該次級繞組242，經該第二整流濾波電路25整流、濾 波後輸出穩定的直流電壓。該初級繞組241的勵磁電流藉 由該保護電路23消耗掉。 對該電源電路20進行過流點測試：當輸入電壓為 100V時，在輸出端250測得過流點為2.61Α，當輸入電壓 為240V時，在輸出端250測得過流點為2.62Α。由此可見， 13 200826462 •該第二整流濾波電路25輸出端250的過流點基本不變。 - 與先前技術相比，本發明電源電路20增加一補償電路 • 31以對輸入侧的電壓進行反饋，當輸入端211、212所連 接的交流電源變化時，該補償電路2〇將輔助繞組3〇之感 應電壓反饋至該脈寬調變控制器29的電壓採樣端292，該 反饋電壓與該反饋電路28的反饋電壓相疊加，該脈寬調變 控制器29將該總反饋電壓與其參考電壓進行比較並發出 相應的控制訊號以控制該電晶體27,從而使該電源電路2〇 輸出端的過流點穩定。 綜上所述，本發明確已符合發明之要件，麦依法提出 專利申請。惟’以上所述者僅為本發明之較佳實施方式， 本發明之範圍並不以上述實施方式為限，舉 藝之人士援依本發明之精神所作之等效修倚或變化，皆 涵蓋於以下申請專利範圍内。 … ν【圖式簡單說明】 圖1係一種先前技術電源電路的電路結構示意圖。 圖2係本發明電源電路的電路結構示意圖。〜 【主要元件符號說明】 電源電路 2〇 第一整流濾波電路 21 保護電路 23 隔離向頻變壓器 24 14 25200826462 第二整流濾波電路 電晶體 反饋電路 脈寬調變控制器 輔助繞組 補償電路 全橋整流電路 濾波電容 初級繞組 次級繞組 限流電阻 控制端 電壓採樣端 二極體 第一電阻 第二電阻 輸出端 輸入端 27 28 29 30 31 213 214 241 242 270 291 292 313 311 312 215 、 250 、 315 211 、 212 、 251 、 252 、 310 15200826462. IX. INSTRUCTIONS: TECHNICAL FIELD OF THE INVENTION The present invention relates to a power supply circuit. [Prior Art] Please refer to Fig. 1, which is a schematic diagram of a circuit structure of a prior art power supply circuit. The power circuit 10 includes a first rectifying and filtering circuit 11, a protection circuit 13, an isolated high frequency transformer 14, a second rectifying and filtering circuit 15, a transistor 17, a feedback circuit 18, and a pulse width modulation controller. 19. The first rectifying and filtering circuit 11 includes two input terminals 111 and 112, a full bridge rectifying circuit 113, a filter capacitor 114 and an output terminal 115. The isolated high frequency transformer 14 includes a primary winding 141 and a primary winding 142. The second rectifying and filtering circuit 15 includes two input ends 151 and 152 and an output end 150. The pulse width modulation controller 19 includes a control end 191 and a voltage sampling end 192. The two input ends of the full bridge rectifier circuit 113 are the two input terminals 111, 112 of the first rectifier filter circuit, and the positive output terminal of the full bridge rectifier circuit 113 is the output terminal 115 of the first rectifier filter circuit, the full bridge The negative output terminal of the rectifier circuit 113 is grounded, and the filter capacitor 114 is connected in parallel between the positive output terminal and the negative output terminal of the full bridge rectifier circuit 113. The protection circuit 13 is connected in parallel with the primary winding 141 of the isolated high frequency transformer 14. One end of the primary winding 141 of the isolated high frequency transformer 14 is electrically connected to the output terminal 115 of the first rectifying and filtering circuit 11, and the other end thereof is electrically connected to the source of the transistor 17. The secondary winding 142 of the isolated high frequency transformer 14 is electrically coupled to the two input terminals 151, 152 of the second rectifying and filtering circuit 15. The gate of the transistor 17 is electrically connected to the control terminal of the m-pulse width modulation controller 19, and the drain of the transistor 17 is connected to the voltage sampling terminal 192 of the pulse width modulation controller 19 by the feedback circuit 18. Electrically connected, the drain of the transistor 17 is simultaneously grounded via a current limiting resistor 170. The external AC voltage is input to the two input terminals 111 and 112 of the first rectifying and filtering circuit 11, and is rectified and filtered by the first rectifying and filtering circuit 11 to be a DC voltage. When the transistor 17 is turned on, the filter capacitor 114, the primary winding 141 of the isolated high frequency transformer 14, the transistor 17 and the current limiting resistor 170 form a loop. At this time, the filter capacitor 114 is equivalent to " ^DC power supply 'The primary winding 141 is equivalent to an inductance'. The formula y = represents the voltage of the filter capacitor 114, L represents the inductance of the primary winding 141 at, and I represents the current flowing through the primary winding 141. The primary winding 141 is known. The current in the line increases linearly and finally reaches the maximum value. The feedback circuit 18 feeds back the voltage of the current limiting resistor 170 to the electrical and voltage sampling terminal 192 of the pulse width modulation controller 19, and the pulse width modulation controller 19 compares the feedback voltage with its reference voltage when the feedback When the voltage is higher than its reference voltage, the control terminal 191 of the pulse width modulation controller 19 outputs a low level to control the transistor 17 to stop operating. When the transistor 17 is turned off, the electric energy stored in the primary winding 141 is transmitted to the secondary winding 142, and is rectified and filtered by the second rectifying and filtering circuit 15 to output a stable DC voltage. The field current of the primary winding 141 is consumed by the protection circuit 13. 9 200826462 However, when the AC power supplies connected to the input terminals 111, 112 are different, the overcurrent point of the straight out terminal 150 changes greatly. For example, when the AC power source is MN, the overcurrent point measured at the output terminal 150 is 2.61A, and when the AC power source is compliant, the overcurrent point is measured at the output terminal 15G. When the voltage of the AC power source connected to the terminal and the (1) is high, the current in the circuit is also large. If the input side or the output side fails, the power supply & ι〇 may be possible. In view of this, it is necessary to provide a power supply path that stabilizes the overcurrent point at the output end. A power supply circuit comprising a first rectifying and filtering circuit, an isolated high frequency transformer, a second rectifying and filtering circuit, a transistor, a feedback circuit, a pulse modulation controller and a compensation circuit. The first rectifying and filtering circuit includes two input ends and an output end. The isolated high frequency transformer includes a primary winding, a primary winding and an auxiliary winding. The second rectifying and filtering circuit includes two input ends and an output. The pulse width modulation controller includes a control terminal and a voltage sampling terminal. One end of the primary winding of the isolated high frequency transformer is electrically connected to the output end of the first rectifying and filtering circuit, and the other end thereof is electrically connected to the source of the transistor; the secondary winding of the isolated high frequency transformer and the second rectifying filter The two input ends of the circuit are electrically connected; one end of the auxiliary winding of the isolated high frequency transformer is electrically connected to the voltage sampling end of the pulse width modulation controller by the compensation circuit, and the other end thereof is grounded. a gate of the transistor is electrically connected to a control end of the pulse width modulation controller; a drain of the transistor is electrically connected to a voltage sampling end of the pulse width modulation controller by the 200826462 feedback circuit, the electricity The bottom of the crystal is grounded at the same time. Compared with the prior art, the power circuit of the present invention adds a compensation circuit to feed back the voltage on the input side. When the AC power source connected to the input terminal changes, the compensation circuit feeds back the induced voltage of the auxiliary winding to the pulse width modulation. a voltage sampling end of the controller, the feedback voltage is superimposed with a feedback voltage of the feedback circuit, and the pulse width modulation controller compares the total feedback voltage with a reference voltage thereof and sends a corresponding control signal to control the transistor, thereby The overcurrent point at the output of the power circuit is stabilized. [Embodiment] Please refer to Fig. 2, which is a schematic circuit diagram of a power supply circuit of the present invention. The power circuit 20 includes a first rectifying and filtering circuit 21, a protection circuit 23, an isolated high frequency transformer 24, a second rectifying and filtering circuit 25, a transistor 27, a feedback circuit 28, and a pulse width modulation controller. 29 and a compensation circuit 31, wherein the first rectification filter circuit 21 includes two input terminals 211, 212, a full bridge rectification circuit 213, a filter capacitor 214 and an output terminal 215. The isolated high frequency transformer 24 includes a primary winding 241, a secondary winding 242, and an auxiliary winding 30. The second rectifying and filtering circuit 25 includes two input ends 251 and 252 and an output end 250. The pulse width modulation controller 29 includes a control terminal 291 and a voltage sampling terminal 292. The compensation circuit 31 includes an input terminal 310, an output terminal 315, a diode 313, a first resistor 311 and a second resistor 312. The two input ends of the full bridge rectifier circuit 213 serve as the two input terminals 211, 212 of the first rectification filter 11 200826462 / circuit 21, and the positive output terminal of the full bridge rectifier circuit 213 serves as the output of the first rectification filter circuit 21. At the terminal 215, the negative output terminal of the full bridge rectifier circuit 21 is grounded, and the filter capacitor 214 is connected in parallel between the positive output terminal and the negative output terminal of the full bridge rectifier circuit 213. The protection circuit 23 is connected in parallel with the primary winding 241 of the isolated high frequency transformer 24. The primary winding 241 of the isolated high frequency transformer 24 is electrically connected to the output 215 of the first rectifying and filtering circuit 21, and the other end thereof is electrically connected to the source of the transistor 27. The secondary winding 242 of the isolated high frequency transformer 24 is electrically coupled to the two input terminals 251, 252 of the second rectifier filter circuit 25. The gate of the transistor 27 is electrically connected to the control terminal 291 of the pulse width modulation controller 29, and the drain of the transistor 27 is connected to the voltage sampling terminal 292 of the pulse width modulation controller 29 by the feedback circuit 28. Electrically connected, the drain of the transistor 27 is simultaneously grounded via a current limiting resistor 270. One end of the auxiliary winding 30 of the isolated high frequency transformer 24 is electrically connected to the input terminal 310 of the compensation circuit 31, and the other end thereof is grounded. The diode 313 and the first resistor 311 are connected in series between the input terminal 310 and the output terminal 315 of the compensation circuit 31, and the cathode of the diode 313 is connected to the first resistor 311. The compensation circuit 31 The output terminal 315 is electrically connected to the voltage sampling terminal 292 of the pulse width modulation controller 29, and is simultaneously grounded by the second resistor 312. The external AC voltage is input to the two input terminals 211 and 212 of the first rectifying and filtering circuit 21, and is rectified and filtered by the first rectifying and filtering circuit 21 to be a DC voltage. When the transistor 27 is turned on, the filter capacitor 214, the primary winding 241 of the isolated high frequency transformer 24, the transistor 27, and the current limiting resistor 270 form a loop. At this time, the filter capacitor 214 and the like 12 200826462 are A DC power supply, the primary winding 241 is equivalent to an inductance, by the formula: v = z! (V represents the voltage of the filter capacitor 214, L represents the inductance of the primary winding 241 'I shows the current flowing through the primary winding 241) It can be seen that the current in the primary winding 241 increases linearly and finally reaches a maximum value. The feedback circuit 28 feeds back the voltage of the current limiting resistor 270 to the voltage sampling terminal 292 of the pulse width modulation controller 29. The auxiliary winding 30, the diode 313, the first resistor 311 and the second resistor 312 also form a loop. In this case, the auxiliary winding 30 is equivalent to a power source, and is represented by the formula: s = m and (ε) The induced electromotive force of the auxiliary winding 30, Μ represents the mutual inductance of the primary winding 241 and the auxiliary winding 30, and I represents the current in the primary winding 241. It is known that the induced electromotive force of the auxiliary winding 30 remains unchanged when the current in the primary winding 241 changes linearly. The voltage of the second resistor 312 is fed back to the voltage sampling terminal 292 of the pulse width modulation controller 29, and the feedback voltage is superimposed with the feedback voltage of the feedback circuit 28, and the pulse width modulation controller 29 uses the total feedback voltage. Compared with its reference voltage, when the feedback voltage is higher than its reference voltage, the control terminal 291 of the pulse width modulation controller 29 outputs a low level to control the transistor 27 to stop operating. When the transistor 27 is turned off, the electric energy stored in the primary winding 241 is transmitted to the secondary winding 242, and is rectified and filtered by the second rectifying and filtering circuit 25 to output a stable DC voltage. The field current of the primary winding 241 is consumed by the protection circuit 23. The overcurrent point test is performed on the power supply circuit 20: when the input voltage is 100V, the overcurrent point is measured at the output terminal 250 to be 2.61 Α, and when the input voltage is 240V, the overcurrent point is measured at the output terminal 250 is 2.62 Α . It can be seen that 13 200826462 • The overcurrent point of the output terminal 250 of the second rectifying and filtering circuit 25 is substantially unchanged. - Compared with the prior art, the power supply circuit 20 of the present invention adds a compensation circuit 31 to feed back the voltage on the input side. When the AC power source connected to the input terminals 211, 212 changes, the compensation circuit 2 turns the auxiliary winding 3 The induced voltage is fed back to the voltage sampling terminal 292 of the pulse width modulation controller 29, and the feedback voltage is superimposed with the feedback voltage of the feedback circuit 28, and the pulse width modulation controller 29 uses the total feedback voltage and its reference voltage. A comparison is made and a corresponding control signal is issued to control the transistor 27 to stabilize the overcurrent point at the output of the power circuit 2. In summary, the present invention has indeed met the requirements of the invention, and Mai has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiments, and the equivalents or variations made by those skilled in the art in accordance with the spirit of the present invention are covered. It is within the scope of the following patent application. ... ν [Simple Description of the Drawings] Fig. 1 is a schematic diagram showing the circuit structure of a prior art power supply circuit. 2 is a schematic diagram showing the circuit structure of a power supply circuit of the present invention. ~ [Main component symbol description] Power supply circuit 2〇First rectification filter circuit 21 Protection circuit 23 Isolation to frequency transformer 24 14 25200826462 Second rectification filter circuit Transistor feedback circuit Pulse width modulation controller Auxiliary winding compensation circuit Full bridge rectifier circuit Filter capacitor primary winding secondary winding current limiting resistor control terminal voltage sampling terminal diode first resistor second resistor output terminal input terminal 27 28 29 30 31 213 214 241 242 270 291 292 313 311 312 215, 250, 315 211 212, 251, 252, 310 15