TWI339485B - Power supply circuit - Google Patents

Description

November 26, 099, g is replacing page. VI. Description of the invention: [Technical field to which the invention pertains] [_1] The present invention relates to a power supply circuit. [Prior Art] [0002] 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, 112, a full bridge rectifying circuit 113, a filter capacitor 114 and an output terminal 115. The isolated high frequency transformer 14 includes four windings 14 lv and a primary stage. The second rectifying and filtering circuit d includes a earth input terminal 152 and an output terminal 150. The pulse width modulation control device 19 includes a control terminal 191 and a voltage sampling terminal 192. [0003] The full bridge The two input ends of the rectifier circuit 113 are an input terminal 111, 112 of the first rectifying and filtering circuit, and the full output of the full bridge, the rectifying circuit, 113, is the output end of the first rectifying and filtering circuit. The full-bridge rectifier circuit η 3 . > '1 ' has a negative output terminal 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 isolated from the isolation circuit 13 The primary winding 141 of the high frequency transformer 14 is connected in parallel. One end of the primary winding 141 of the isolated high frequency transformer 14 is electrically connected to the output 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 14 2 of the isolated high frequency transformer 14 The two input terminals 151, 152 of the second rectifying and filtering circuit 15 are electrically connected. The gate of the transistor 17 is electrically connected to the control terminal of the pulse width modulation controller 19 'The bottom of the transistor 17 is borrowed from the form number Α 0101 Page 5 of 16 pages 0993426403-0 1339485 November 2, 299

The feedback circuit 18 is electrically connected to the voltage sampling terminal 192 of the pulse width modulation controller 19, and the drain of the transistor 7 is grounded simultaneously by a current limiting resistor 1 70.

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 17 0 form a loop. At this time, the filter capacitor 114 is equivalent The power supply, the primary winding 141 is equivalent to an inductance, by the formula: (v represents the voltage of the wave capacitor 114, L represents the inductance of the primary winding 141, and I represents the electricity flowing through the primary winding 41: 蛉. The flow linearly increases 'finally reaches the maximum voltage of the current limiting resistor 170 to the voltage sampling terminal 192 of the pulse width modulation controller, and the pulse width modulation controller 19 compares the feedback voltage with its reference voltage. When the feedback voltage is higher than its reference voltage, the control terminal 1 91 of the pulse width modulation controller L 9 outputs a low level to stop the operation of the germanium crystal 17. [0005] When the transistor 17 At the time of the cutoff, 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 excitation current of the primary winding 141 is provided by the protection circuit 13 Consumed. [0006]

However, when the AC power sources connected to the input terminals 111, 112 are different, the overcurrent point of the output terminal 150 changes greatly. 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 When the input terminal ln, 095144727 Form No. Α0101 Page 6 / Total 16 Page 0993426403-0 1339485 _ November 26, 2017, the voltage of the AC power supply connected to the page 112 is high, the current in the circuit is also corresponding Large, if the input side or the output side fails, the power circuit 10 may be burned. SUMMARY OF THE INVENTION [0007] In view of the above, it is necessary to provide a power supply circuit that stabilizes an overcurrent point at an output terminal.

[0008] A power supply circuit includes a first rectifying and filtering circuit, an isolated high frequency transformer, a second rectifying and filtering circuit, a transistor, a feedback circuit, a pulse width modulation controller, and a compensation circuit. Wherein, the first rectifying and filtering circuit comprises two input ends and an output end, the isolated high frequency variable voltage, the .:. 'i' device comprises a primary winding, a primary level 遂 group friend and an auxiliary winding, the second rectifying filter The circuit includes two inputs 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 The two input ends of the filter circuit are electrically connected; the auxiliary burner end 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 feedback circuit, the transistor The drain circuit is simultaneously grounded by a current limiting resistor. The compensation circuit includes a diode, a first resistor and a second resistor. The anode of the diode is electrically connected to one end of the auxiliary winding of the isolated high frequency transformer. The negative electrode is electrically connected to the voltage sampling end of the pulse width modulation controller by the first resistor, and the voltage of the pulse width modulation controller is 095144727. Form number Α0101 Page 7/16 pages 0993426403-0 1339485 November 26 The Japanese core is replacing the sampling terminal and is grounded by the second resistor. 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 changes, the compensation circuit feeds back the induced voltage of the auxiliary winding to the pulse. a voltage sampling end of the wide modulation controller, the feedback voltage is superimposed with a feedback voltage of the feedback circuit, the pulse width modulation controller compares the total feedback voltage with a reference voltage thereof and sends a corresponding control signal to control the electricity The crystal is such that the overcurrent point at the output of the power supply circuit is stabilized.

[Embodiment]

[0010] Please refer to FIG. 2, which is not intended to be a circuit structure of the power supply circuit of the present invention. The power circuit 20 includes a first rectification circuit 2, an isolation high frequency transformer 24, a transistor 27, a feedback circuit 28, a pulse width modulation controller 29, and a compensation circuit 31. The first rectifying and filtering circuit 21 includes two input terminals 211 and 212, a full bridge rectifying circuit 213, a filter capacitor 214 and an output end 215. The isolated high frequency transformer 24 includes a primary winding 241, a primary winding 242, and an auxiliary winding 30. The second rectifying and filtering circuit 25 includes two input terminals 251, 252 and an output terminal 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. [0011] The two input ends of the full bridge rectifier circuit 213 serve as the two input terminals 211, 212 of the first rectifier filter circuit 21, and the positive output terminal of the full bridge rectifier circuit 21 3 serves as the output of the first rectifier filter circuit 21. Terminal 21 5, the negative output terminal of the full bridge rectifier circuit 213 is grounded, and the filter capacitor 214 is connected in parallel to the full bridge 095144727 Form No. A0101 Page 8 / Total 16 Page 0993426403-0 1339485

Corrected replacement page I on November 26, 099

Between the positive output terminal and the negative output terminal of the rectifier circuit 2 1 3 . The protection circuit 2 3 is connected in parallel with the primary winding 2 41 of the isolated high frequency transformer 24. The primary winding 241-terminal 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 rectifiers 251, 252 of the second rectifying nucleus 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. The drain of the transistor 27 is electrically connected to the ground by a current limiting resistor 270. The auxiliary winding 3 of the isolated local frequency transformer 24 is electrically connected to the input terminal 310 of the compensation circuit 31, and the other end is grounded. The diode 313 and the first resistor 311 are connected in series between the input end 310 and the output end 31 5 of the brick filling material, and the diode 313 ( The negative pole is connected to the first resistor 311, and the output end 315 of the compensation circuit 31 is electrically connected to the voltage sampling terminal 292 of the pulse width modulation controller 29, and is simultaneously grounded by the second resistor 31 2

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 cleaning group 241 of the isolated high frequency dust collector 24, the electrical crystal 27 and the current limiting resistor 270 form a loop. At this time, the filter capacitor 214, etc. The primary winding 241 is equivalent to an inductor. The equation is: (V represents the voltage of the filter capacitor 214, L represents the inductance of the primary winding 241, and I represents the current flowing through the primary winding 241). The primary winding is known. The current in 241 increases linearly* Finally reaches the maximum value β. The feedback circuit 28 converts the current limit 095144727 form number Α0101 page 9/16 pages 0993426403-0 1339485 09 November 26 26 S replaces the voltage of the page resistor 270 Feedback to the voltage sampling terminal 292 of the pulse width modulation controller 29. [0013] The auxiliary winding 30, the diode 31 3, the first resistor 311 and the second resistor 312 also constitute a loop. At this time, the auxiliary winding 30 is equivalent to a power source, by the formula: [0014] ] s = Μ color dt

[0015] (ε represents 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 the current of the il primary) can be found in the current winding of the primary winding 241 in the following: The induced electromotive force of 30 remains unchanged, and 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 control The controller 29 compares the total feedback voltage 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.

[0017] 095144727 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 2.61A, and when the input voltage is 240V, the overcurrent point is measured at the output terminal 250. 62A. It can be seen that the first form number A0101 page 10 / total 16 pages 0993426403-0 1339485 November 26, 099, according to the positive replacement page 2, the rectification filter circuit 2 5 output terminal 2 50 0 overcurrent point is basically unchanged.

[0018] 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 20 will assist the winding 30. 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. The pulse width modulation controller 29 performs the total feedback voltage and its reference voltage. The corresponding control signal is compared and issued to control the transistor 27 to stabilize the overcurrent point at the output of the power circuit 20. [0019] In summary, the present invention has indeed met the requirements of the invention, and the patent application is filed according to law. However, the above description is only the preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiments, and those skilled in the art will be able to make equivalent modifications or variations in accordance with the spirit of the present invention. All should be covered by the following patent application. BRIEF DESCRIPTION OF THE DRAWINGS [0020] FIG. 1 is a schematic diagram of a 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] [0022] Power supply circuit 20 [0023] First rectification filter circuit 21 [0024] Protection circuit 23 [0025] Isolation high-frequency transformer 24 [0026] Second rectification chopper circuit 25 Form No. A0101 No. 11 Page / Total 16 pages 095144727 0993426403-0 1339485 | November 26, 099 Correction replacement [0027] Transistor [0028] Feedback circuit [0029] Pulse width modulation controller [0030] Auxiliary winding [0031] Compensation circuit [0032 Full-bridge rectifier circuit [0033] Filter capacitor [0034] Primary winding [0035] Secondary winding [0036] Current-limiting resistor [0037] Control terminal [0038] Voltage sampling terminal [0039] Diode [0040] First resistor [0041] second resistor [0042] output [0043] input

, 250 , 315 , 212 , 251 , 252 ' 310 095144727 Form Number A0101 Page 12 16 0993426403-0

Claims (1)

1339485 November 26, 099 nuclear replacement page VII, the scope of application for patents: 1 . 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 width modulation controller, and a compensation circuit, wherein The first rectifying and filtering circuit includes a second wheel input end 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 end. The wide-modulation variable controller includes a control end and a voltage sampling end. The primary winding end of the isolated high-frequency transformer is electrically connected to the output end of the first rectifying and filtering circuit, and the other end is electrically connected to the source of the transistor. The secondary winding of the isolated high-frequency transformer is connected to the two-input terminal of the second rectifying and filtering circuit, and the 高频 of the high-frequency transformer is separated: '· ' ' One end of the auxiliary winding is raised by the compensation electroacoustic The voltage sampling end of the 1'_variable controller is electrically connected, and the other end thereof is connected to i, and the gate of the transistor is electrically connected to the control end of the pulse width modulation controller, and the drain of the transistor is Feedback circuit electrically connected to the voltage sampling end of the PWM controller, the transistor * The bungee pole simultaneously includes a diode, a first resistor and a second resistor, and the anode of the diode and the auxiliary winding end of the isolated high frequency transformer Electrically, the negative pole is electrically connected to the voltage sampling end of the pulse width modulation controller by the first resistor, and the voltage sampling end of the pulse width modulation controller is simultaneously grounded by the second resistor. The power supply circuit of claim 1, wherein the first rectifying and filtering circuit comprises a full bridge rectifying circuit and a filter capacitor, and the two input ends of the full bridge rectifying circuit are two inputs of the first rectifying and filtering circuit The positive output end of the full bridge rectifier circuit is the output end of the first rectifying and filtering circuit, the negative output end of the full bridge rectifying circuit is grounded, and the filter capacitor is connected in parallel at the 095144727 Form No. A0101 Page 13 of 16 0993426403-0 1339485 1 n〇Q at " Η κ 棋 711 换 换 δ δ * II « « « « « « « « « « « « « « « « >· ▲^円 w,Γ Ν I Between the positive output and the negative output of the full-bridge rectifier circuit. 095144727 Form No. A0101 Page 14 of 16 0993426403-0